Drainage Needs Reports Protocols

Drainage Needs

Reports Protocols

December 2002

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Public Works Surface Water Management Division

2731 Wetmore Avenue, 2nd Floor Everett, WA 98201

425-388-3464

Responsible County Officials The Drainage Needs Report (DNR) Project is an innovative two-year project that was initiated by the Snohomish County Council in 2001. The project was completed under the direction of the following Snohomish County government officials:

2002 Snohomish County Council: • John Koster - Council District 1 • Kirke Sievers - Council District 2 • Gary Nelson - Council District 3, Council Chair • Dave Gossett - Council District 4 • Jeff Sax - Council District 5

Snohomish County Executive: • Bob Drewel

Snohomish County Public Works: • Public Works Director: Peter Hahn • Public Works, SWM Division Director: Joan Lee, P.E. • DNR Project Director: Loren Sand, P.E. • DNR Technical Manager and SWM Coordinator: Gregg Farris, P.E. • Snohomish County SWM Drainage Supervisor: Karen Kerwin, P.E.

X011084_3538 Responsible County Officials ii December 2002

Preface This Drainage Needs Reports Protocols document is a record of the methods used to collect and analyze data for Snohomish County’s Drainage Needs Reports (DNR) project, conducted in 2001 and 2002. These reports were prepared by various technical leads on the DNR consultant teams and were used by the DNR consultants in developing the 11 separate Drainage Needs Reports. The protocols were written during the DNR project. No attempt was made to rewrite these protocols for use after the DNR project (for example, each section is still written in the present tense). The DNR project was conducted in coordination with Snohomish County Public Works, Surface Water Management Division (SWM), by consultant teams that included R. W. Beck, CH2M Hill, Northwest Hydraulic Consultants, Aqua Terra Consultants, Parametrix, Entranco, Herrera Environmental Consultants, Perkins Geosciences, TerraLogic GIS, TetraTech/KCM, Otak, and GeoEngineers. These protocols were prepared and reviewed by the following lead staff: Project Managers: John Rogers, P.E., CH2M Hill

Steve Swenson, P.E., R. W. Beck

Hydrologic Modeling Protocols:

Malcolm Leytham, P.E., Northwest Hydraulic Consultants

Gregg Farris, P.E., SWM DNR Lead

Hydraulic Modeling Protocols:

Greg Gaasland, P.E., TetraTech/KCM Gregg Farris, P.E., SWM DNR Lead

Habitat Assessment and Analysis Protocols:

Bill Kleindl, Parametrix Darrell Smith, SWM DNR Habitat Lead

Water Quality Analysis Protocols:

Mark Ewbank, P.E., Herrera Environmental Consultants Gary Minton, P.E., Ph.D., Resource Planning Associates

CIP Cost Estimating Unit Prices:

Dave Hedglin, P.E., CH2M Hill

X011084_3538 Preface iii December 2002

Contents I. Hydrologic Modeling Protocols II. Hydraulic Modeling Protocols III. Habitat Assessment and Analysis Protocols

III.A Physical Habitat Survey and Monitoring Protocol for Wadable Streams

III.B Wetland Assessment Methods III.C Riparian Assessment Methods III.D Culvert Assessment Protocol for DNR Streams III.E B-IBI Sampling Protocol for DNR Streams

IV. Water Quality Analysis Protocols

IV.A Protocols for Preparation of Water Quality Pre-Draft Report Sections

IV.B Guidance on Stormwater Quality Improvement Options V. Cost Estimating Unit Prices

X011084_3538 Contents v December 2002

Volume I Hydrologic Modeling

Protocols Version 1.4

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425-388-3464

Contents 1.0 Modeling Tools ....................................................................................................1-1

2.0 Subbasin Breakdown/Delineation and Model Output Locations....................2-1

3.0 Land Use Analysis ..............................................................................................3-1

3.1 Existing Land Use......................................................................................3-1 3.2 Future Land Use........................................................................................3-3 3.3 Critical Areas .............................................................................................3-4 3.4 Effective Impervious Area Percentages ....................................................3-4 3.5 Pervious Cover and Forest Retention .......................................................3-4 3.6 Products ....................................................................................................3-5

4.0 Soils/Surficial Geology .......................................................................................4-1

5.0 Land Surface Slopes...........................................................................................5-1

6.0 Hydrometric Data ................................................................................................6-1

7.0 HSPF PERLND Definitions and Parameter Estimation ....................................7-1

7.1 PERLND/IMPLND Acreages .....................................................................7-1 7.2 HSPF PERLND Parameters......................................................................7-1

8.0 Design and Assembly of UCIs ...........................................................................8-1

8.1 General......................................................................................................8-1 8.2 Numbering of PERLND and RCHRES Operations and DSNs ..................8-1 8.3 Numbering of MASS-LINK Block...............................................................8-2 8.4 FTABLES...................................................................................................8-2 8.5 Detention Ponds for Existing and Future Development.............................8-3 8.6 Rain and Evaporation from Lakes .............................................................8-4 8.7 Hydraulic Routing Stability.........................................................................8-5

9.0 Setting Up WDM ..................................................................................................9-1

9.1 DSN Attributes...........................................................................................9-1

10.0 Analyses and Presentation of Modeling Results ...........................................10-1 10.1 Flood and Stage Frequency Analysis......................................................10-1 10.2 Flow Duration ..........................................................................................10-1 10.3 Flow Statistics..........................................................................................10-2 10.4 Input to Habitat and Water Quality Analysis ............................................10-2 10.5 Input to Hydraulic Models ........................................................................10-3

11.0 Documentation and Quality Control................................................................11-1

11.1 Documentation ........................................................................................11-1 11.2 Quality Control.........................................................................................11-2 11.3 Archiving of Model and Results ...............................................................11-3

X011084_3538 Contents iii December 2002

Hydrologic Modeling Protocols

Figures 1 Future Land Use SCHEMATIC Block Construction ....................................... 11-4 2 Example HSPF Model Schematic .................................................................. 11-5 Tables 1 Sub-Basin Attributes....................................................................................... 11-6 2 Impervious Area Percentages by Existing Land Use ..................................... 11-7 3 Future Land Use Classes and Associates Cover........................................... 11-8 4 Allowable Existing to Future Land Use Conversions...................................... 11-9 5 Soils Types and HSPF Classification ........................................................... 11-10 6 Swamp Creek (excl. Scriber) HSPF Model Parameters............................... 11-11 7 Scriber Creek HSPF Model Parameters ...................................................... 11-12 8 North Creek HSPF Model Parameters ......................................................... 11-13 9 Quilceda Creek HSPF Model Parameters.................................................... 11-14 10 Generalized HSPF Model Parameters ......................................................... 11-15 11 PERLND/IMPLND Numbering...................................................................... 11-16 12 RCHRES/COPY Numbering and Associated DNS Number ........................ 11-17 13 MASS-LINK Block ........................................................................................ 11-18 Appendices A Critical Area Definitions and ESA Buffers B Hydrologic Modeling QA/QC Checklist

X011084_3538 Contents iv December 2002

1.0 Modeling Tools Hydrologic modeling will be done using a customized version of HSPF to be provided by Aqua Terra. This version supports a larger number of operations than official releases of HSPF but is otherwise compatible with official releases of the model.

WDM files should be set up using the latest version of ANNIE (Version 4.0). Earlier versions should not be used since they may not support a number of attributes necessary for anticipated future applications of GENSCN.

X011084_3538 1.0 Modeling Tools 1-1 December 2002

2.0 Subbasin Breakdown/Delineation and Model Output Locations

Each DNR area has been divided into basins and these basins will be divided into subbasins for the purpose of hydrologic modeling.

Subbasin delineation will define:

• principal tributary streams

• outflows from major lakes, wetlands, regional detention facilities, and other regional stormwater management facilities

• locations of principal flooding and flow-related habitat, water quality, or geomorphic problems for which model output is required

• Lakes with surface area greater than about 5 acres should be delineated as their own unique subbasin. Subbasin boundaries for lakes should follow the lake shore, only including the lake surface area.

Subbasins will be delineated in either hard copy or digital form by the DNR team and then submitted to the County for review and approval. After review by the County the delineation will be forwarded to the GIS consultant for use in land-use, soils, and slope analyses.

Controlling the number of subbasins and output points is crucial to controlling costs and schedule. The following guidelines will be used for subbasin delineation:

• Subbasins will be as large as possible up to a maximum size of about 400 acres.

• Larger subbasins will generally be used for areas with low existing development density and few known historical drainage problems.

• Subbasin areas will generally not be smaller than 40 acres, except in unusual situations, such as urbanized areas with drainage systems that will be analyzed in detail.

Subbasins should be numbered by the DNR team in increments of 10 (or less depending on the number of sub-basins being modeled) starting with the most downstream sub-basin and working upstream (see Section 8.2 for further numbering details). For DNR areas in which hydrologic modeling is being split between several consultants (e.g. Swamp Creek), the numbering system must be carefully coordinated by the DNR Lead to ensure that all modeled basins can be incorporated into a single model on completion of the project.

Subbasin delineation should be based on best available topographic mapping, previous studies, and available drainage plans. Uncertainties in subbasin delineation (where subbasin areas could change by +/- 10% or more) should be resolved by reference to development plan sheets on file at the County and by field reconnaissance.

X011084_3538 2.0 Subbasin Breakdown/Delineation and Model Output Locations 2-1 December 2002


Subbasin delineations by individual DNR teams may lead to overlap in DNR area boundaries. TerraLogic will be responsible for checking for such overlap and will coordinate adjustments or corrections with the DNR teams.

For each subbasin, the attributes shown in Table 1 should be provided in EXCEL by the DNR team. These attributes will be used by TerraLogic in the generation of HSPF MASS-LINK and SCHEMATIC blocks.

X011084_3538 2.0 Subbasin Breakdown/Delineation and Model Output Locations 2-2 December 2002

3.0 Land Use Analysis Land use analysis will be undertaken by the GIS Consultant.

The following land use conditions will be analyzed:

• existing land use conditions

• one future land use scenario to be based on existing County land use plans

3.1 Existing Land Use Existing land use will be broken down into the following categories as shown in Table 2:

• open water (generally open water bodies larger than 1 acre)

• forest

• pasture

• grass

• rural single family residential (less than or equal to 1 unit per 5 acres)

• low density single family residential (1 unit per 5 acres to 2 units per acre)

• medium density single family residential (2 to 6 units per acre)

• high density single family residential (greater than 6 units per acre)

• multi-family residential

• commercial/industrial

• roads

Existing Land Use will be defined as of 1998 based on current assessor file and validation using 1998 aerial photographs.

Since existing land use will be determined from assessor files, all roads will be identified as a separate land use and, for example, single family residential areas identified through the analysis will comprise the residential lots only, excluding the roads that service those areas.

Lakes and other water bodies with surface areas greater than 5 acres will be delineated as their own unique subbasin, as noted in Section 2.0. Lakes will be modeled in HSPF as RCHRES elements of fixed surface area with rainfall on and evaporation from the lake surface.

Water bodies with a surface area of less than 1 acre identified through the assessor files will be merged with and considered part of the surrounding land use. For example, on-site detention facilities in single family residential areas identified through the assessor

X011084_3538 3.0 Land Use Analysis 3-1 December 2002


files will have their reported areas simply added to the area under single family residential use.

Water bodies larger than 1 acre but smaller than 5 acres could be of significance in attenuating flows depending on the size of their tributary areas. Where these water bodies are identified from the assessor files, they will be reported through the GIS analysis and in the generated SCHEMATIC blocks as "WATER". The DNR team will be responsible for examining these on a case by case basis to determine whether they can be merged with the surrounding land use or whether they should be modeled as separate water bodies in HSPF. A brief review indicates that the great majority of water bodies identified in the assessor files are smaller than 1 acre and only a relatively small number fall in the 1 acre to 5 acre size range.

The County will provide assessor information and TerraLogic will convert this information into a GIS coverage representing existing land use. Correspondence between land use codes in the assessor files and HSPF land use classes will be established for project-wide use by the GIS Consultant in consultation with the Hydrology Technical Lead. The existing land use mapping produced under the GIS task will be spot checked against current aerial photography of the DNR area by TerraLogic to ensure that interpretation of assessor files is reasonable. TerraLogic will also check the maps to ensure that all areas within each subbasin are accounted for. Final comprehensive checks of the existing land use maps will be the responsibility of the DNR teams. Terralogic will produce maps that show:

• existing land use superimposed on 1998 aerial photos

• existing rural density and low density single family residential areas and subbasin boundaries superimposed on 1998 aerial photos

The maps will be checked by the DNR teams for:

• conformance with defined land use classes,

• correct interpretation of land use for 1998 conditions,

• correct interpretation of pervious land cover (pasture, grass, or forest)

Limited field reconnaissance may be required to resolve uncertainties in land use. All modifications to be made to the existing land use maps should be communicated to TerraLogic. TerraLogic will be responsible for making changes and for maintaining all GIS coverages for the project.

The following points should be notes:

• Since the assessor information is more current that the 1998 aerials, there are situations where the assessor files show development that had not occurred as of 1998. In such situations, the land use map should be modified to reflect 1998 conditions as indicated by aerial photographs.

• Certain large non-residential parcels such as schools have been split by TerraLogic into impervious and pervious parts, with the impervious part assigned a commercial use and the pervious part designated as grass, pasture or forest. This has been done by visual inspection of aerial photographs. Checks should be made to ensure that all such parcels have been identified and correctly classified.



• Rural density and low density residential lots have a high percentage of forest cover in some areas. The DNR team will need to specify a percent existing forest cover for rural and low density lots by subbasin for inclusion in the subbasin attributes file. This information will be used by TerraLogic in the generation of SCHEMATIC blocks. It is expected that the percentage forest cover will be estimated by visual inspection of maps showing rural and low density residential areas superimposed on 1998 aerials to be provided by TerraLogic.

3.2 Future Land Use Future land use analysis will be based on available General Policy Plan (GPP) information to be obtained under the GIS task from the County. Correspondence between future land use classes and HSPF land use classes will be established for project-wide use by TerraLogic in consultation with the Hydrology Technical Lead. The future land use classes are listed in Table 3 and are discussed further under Sections 3.4 and 3.5. Future land use maps and acreages of existing to future land use conversions provided by TerraLogic will be checked for accuracy and completeness by the DNR Teams.

Areas of new development or redevelopment will be determined by TerraLogic based on comparison of future and existing land use. A matrix showing allowable existing to future land use conversions is provided in Table 4. The following development or redevelopment “rules” will be followed:

• Existing undeveloped, rural density residential, and low density residential areas will be assumed to redevelop to higher density land use class unless in a designated critical area, except as noted below under Critical Areas. Undeveloped, rural density residential, and low density residential in critical areas will be assumed to remain unchanged.

• No existing medium and high density residential will be assumed to redevelop to higher density. If such redevelopment does occur then it will likely be of older residential areas with no or minimal stormwater control facilities. It is assumed that new detention facilities constructed under redevelopment will result in a reduction in a net post-redevelopment peak flows due to the requirement that existing conditions be assumed forested for redevelopment projects (Title 24.30.025 and 24.70.150).

• No existing parks will be assumed to redevelop.

• No areas identified as grass will be assumed to redevelop. These encompass ball fields, golf courses, school sport fields, cemeteries, etc.

• No identified high voltage power line rights of way will be assumed to redevelop.

• 30% to 50% of pervious areas (total area less gross impervious area) will be assumed to be retained in forest for conversion from forest to rural or low density residential. No forest retention will be assumed for higher density developments. Estimates of forest retention will be provided by sub-basin by the DNR teams (see Section 3.5).

• No redevelopment to a lower density will occur.

Future land use information will not be totally consistent with existing land use in that the future land use data will not identify new roads as a separate land use.



3.3 Critical Areas Critical areas and their buffers and setbacks will be protected from new future development as per critical area ordinances, except that new development to zoned densities will be assumed on slopes between 33% and 40%, with no development on slopes greater than 40% and their setbacks (see also Section 5.0). A description of critical area assumptions prepared by Terra Logic is attached as Appendix A. No consideration will be given to the effects of density credits on development encompassing Critical Areas.

3.4 Effective Impervious Area Percentages Both gross and effective impervious area (EIA) are dependent to some extent on the age of development. Older residential areas frequently have a smaller EIA because, for example, roof downspouts may be discharged to splashpads instead of being tied into the storm drain system. Roads in older areas may have a smaller area of pavement but the same overall width of right of way (smaller gross impervious area). Roads in older areas may also have relatively ineffective open ditch drainage (low effective percentage) as compared to curb and gutter for new developments. To account for these variations, three effective impervious area tables have been defined. Proposed impervious and effective impervious area percentages are provided in Table 2 for existing land uses, and in Table 3 for future land use.

The DNR team must provide an EIA table number (as shown in Table 2) for each subbasin for the existing condition land-use analysis to be conducted by the GIS Consultant. It is expected that table EIA#1 would be applicable to old residential neighborhoods where rooftop drainage is primarily via downspouts and road pavement only occupies part of the right of way. EIA#2 would be applicable to more recent development where roads are primarily curb and gutter and where roof tops are more likely to be tied in to the storm drain system. EIA#3 is intended for very recent development with the tendency for greater impervious coverage on a lot and a high proportion of the impervious surface connected to the storm drain system.

Effective impervious percentages for new development or redevelopment under the future land use scenario are provided for each future land use class in Table 3. Note that the since future land use does not separately identify roads, the EIA’s for future development are assumed to incorporate the paved area of new roadways.

3.5 Pervious Cover and Forest Retention Pervious areas (comprising true pervious areas plus non-effective impervious areas) will be assumed to be forest, pasture, or grass1, depending on the land use. For existing land use classes, the assumed pervious cover types are shown in Table 2. For rural density and low density residential areas, it is assumed that the pervious area is split into forest, pasture, and grass, according to the default percentages shown in Table 2. Inspection of a sample of aerial photos shows that cover on these low and rural density lots is highly variable from close to 100% forest to close to 100% pasture or grass. For these existing classes, the DNR teams should determine the approximate percentage of

1 The terms “grass” and “lawn” are used interchangeably for the same cover type and encompass residential lawns, play fields, golf courses, etc – generally any type of heavily maintained grass surface.



forest cover by sub-basin using mapping (rural density and low density residential areas superimposed on 1998 aerials) to be provided by TerraLogic (see also Table 1). The default assumption for the non-forested pervious areas will be 80% pasture and 20% grass (lawn).

Similar pervious cover information for future land use classes is shown in Table 3. For the future rural residential categories, forest retention will play an important role in determining runoff amounts. For these categories, the future cover will depend on the existing cover. Land use conversions of concern are existing forest, pasture and rural density residential to the various future rural density residential categories. It will be assumed that certain percentages of the existing forest cover will be retained in the future with the percent retention varying by future development density. Default percent retention values for the future rural density categories of concern are provided in Table 1 (the subbasin attributes table). For example from Table 1, it is assumed that 30% of the existing forest cover would be retained in future rural residential developments with densities of 1 unit / 5 acres. Suppose the DNR team had determined that existing rural density residential areas had 50% forest cover (as indicated in row 13 of Table 1), then the forest cover under future rural density development at 1 unit / 5 acres would be 15%. Non-forested pervious areas in the future rural residential categories will be assumed to be 80% pasture and 20% grass (lawn).

3.6 Products TerraLogic will provide existing and future land use maps and tabulated land use by sub-basin for review by the DNR team for each area to be modeled. TerraLogic will also provide a summary table of existing to future land-use conversions for review by the DNR teams. TerraLogic will modify the land-use maps as necessary based on DNR team review.


4.0 Soils/Surficial Geology Soils will be classified by the County into one of four categories: till, outwash, Custer Norma, and saturated (wetland). The classification will be based on a correspondence between soil type or surficial geology and category established by the County in consultation with the Hydrology Technical Lead as shown in Table 5. Coverage of saturated areas will be augmented by TerraLogic by overlaying the available wetland coverage and the soils coverage. The DNR team will review the soils and available surficial geologic data and refine the mapping and categorization if necessary to reflect considerations such as the following:

• outwash soils overlying till at shallow depth (less than about 5 feet) should be classified as till

• outwash soils known to be seasonally saturated should be classified as saturated

• inconsistencies between surficial geologic mapping and soils information will be resolved where possible through consultation with the County geologist or the team geomorphologist.

Areas of outwash soils in the Quilceda Creek basin are understood to be seasonally saturated.

Edits from the DNR Team will be incorporated into the GIS coverages by the County and the final maps will be submitted to TerraLogic for use in production of HSPF SCHEMATIC inputs.

X011084_3538 4.0 Soils/Surficial Geology 4-1 December 2002

5.0 Land Surface Slopes Areas to be modeled will be classified by slope by the County according to the following categories:

• 0% < Flat # 6%

• 6% < Moderate # 15%

• 15% < Steep # 40%

• 40% < Very Steep

Steep and very steep slopes (i.e. all land with a slope greater than 15%) will be lumped for the purposes of determining hydrologic response.

According to the Critical Areas ordinance, development is restricted, but still possible with appropriate geotechnical input, on slopes steeper than 33%. To account for some limited level of development on slopes steeper than 33%, it will be assumed that land on slopes between 33% and 40% can be developed or redeveloped to zoned densities (per the rules in Section 3.2) but that no new development or redevelopment can occur on slopes greater than 40% or their setbacks. Analysis of slopes will be conducted by the County. Slope coverages will be provided by the County to the DNR team for review and to TerraLogic for analysis and development of HSPF SCHEMATIC blocks.

X011084_3538 5.0 Land Surface Slopes 5-1 December 2002

6.0 Hydrometric Data Aqua Terra will provide 15-minute rainfall data in WDM format from September 1948 through September 1997 for the following sites:

• Everett

• Silver Lake (North Creek)

• Alderwood (Swamp Creek)

• Soper Hill (Allen Creek)

• Smokey Point (Quiceda Creek)

The Silver Lake, Alderwood, Soper Hill, and Smokey Point data were developed by transposing long-term data from Everett to the site of interest and then appending the available short-term at-site data collected by Snohomish County.

Snohomish County will provide 15-minute rainfall data in usable ASCII format for Silver Lake, Alderwood, Soper Hill, and Smokey Point from October 1997 through September 2000. These data will be used to extend rainfall time series in WDM format through September 2000 for HSPF applications (see also Section 9.0). Responsibility for rainfall time series extensions through September 2000 are as follows: Aqua Terra: Silver Lake

Soper Hill

NHC: Alderwood Sno. Co.: Smokey Point The flood of record for many locations in Snohomish County was the rain-on-snow event of late December 1996/early January 1997. Precipitation and temperature data for this event will be examined by the DNR teams and the precipitation data modified as necessary to represent liquid water inputs to the soil horizon over the course of the event. More detailed data on snow fall and temperature should be obtained by the DNR team (suitable temperature data as well as snow on the ground data may be obtained from the NOAA cooperative stations or can be provided by the Hydrology Technical Lead on request). The following general approach will be used:

• Precipitation from 26 December through noon on December 29 will be assumed to either fall as snow or be retained in the snowpack with no liquid water input to the soil horizon.

• The accumulated snow water equivalent will be melted at a uniform rate and added to rainfall from noon on 29 December through about 8 am on 31 December.

Precipitation data in the WDM for this event will be modified as outlined above to represent liquid water inputs to the soil horizon. (A more sophisticated analysis of the

X011084_3538 6.0 Hydrometric Data 6-1 December 2002


Silver Lake precipitation data has been conducted for this event with snow melt contributions computed using a simple temperature-indexed melt algorithm rather than using a uniform melt rate. The modified Silver Lake precipitation time series is available from Robin Kirschbaum at R.W. Beck.) Any significant proposed departure from the above approach should be discussed with the Hydrology Technical Lead. The division of responsibilities for this work will be the same as for the rainfall time series extension noted above.

Data in the extended rainfall series will be checked to ensure that maximum annual 15-minute and hourly intensities are reasonable. Periods showing intensities greater than 0.4 inches per hour or 0.2 inches in 15 minutes will be checked for possible gage errors. Reported amounts will be redistributed if data patterns indicate likely gage error.

The extended data series from one or more of the above sites will be transposed to the basins and sub-basins of interest by the DNR team hydrologist by scaling on the basis of ratio of sub-basin against rain gage mean annual rainfall. A maximum of four different transposition factors may be used to allow consistency with the PERLND and IMPLND numbering conventions described in Section 8.2. The scaling of rainfall will be accomplished in the HSPF model by use of the multiplication factor in the SOURCES block. Mean annual rainfall for sub-basins may be estimated from the most recent isohyetal maps prepared by the Oregon Climate Service (OCS). The OCS maps and gage mean annual rainfall should be checked for consistency to ensure the best possible estimate of transposition factor. OCS maps can be seen at www.ocs.orst.edu/prism.

Daily pan evaporation data will be provided in WDM format by Aqua Terra for the period September 1948 through September 2000 for the following site:

• Puyallup Experimental Station

This time series was developed from the available daily record for water years 1960 through 1997. For the most part, this station only measured pan evaporation during the growing season. Data for winter months was filled using the Jensen-Haise equation. Data for water year 1960 were transposed without change to water years 1949 through 1959 and water years 1998 through 2001.

Pan evaporation coefficients ranging from 0.7 to 0.8 have been used in previous HSPF modeling work within Snohomish County, as follows:

• Swamp, North, Quilceda (USGS, 1986 - for generalized HSPF modeling) – 0.75

• Lake Stevens (Snohomish County, 2000) – 0.70

• Quilceda (Snohomish County, 1995) – 0.76

• Swamp Creek (Snohomish County, 1994) – 0.80

• North Creek (Snohomish County, date unknown) – 0.70

Given uncertainty in evaporation data and the inter-dependency between modeled evaporation rates and model parameters, greatest weight should be given to pan evaporation coefficients used in model calibrations. Pan coefficients used for the present study will therefore be those determined by calibration, or the coefficient used by the USGS for study areas where generalized HSPF parameter values are to be used. The pan coefficients to be used are then as follows:



Watershed Pan Coefficient

SW UGA, Puget Sound Drainages, Sunnyside, Allen

0.75

Swamp 0.80 Quilceda 0.76 North, Marshland 0.70


7.0 HSPF PERLND Definitions and Parameter Estimation

7.1 PERLND/IMPLND Acreages Land use, soils, and slope coverages will be analyzed by TerraLogic to determine acreages by subbasin for each of the following 19 PERLNDs/IMPLNDs:

• Till Forest Flat/Moderate/Steep Slopes (TFF, TFM, TFS)

• Till Pasture Flat/Moderate/Steep Slopes (TPF, TPM, TPS)

• Till Grass Flat/Moderate/Steep Slopes (TGF, TGM, TGS)

• Outwash Forest All Slopes (OF)

• Outwash Pasture All Slopes (OP)

• Outwash Grass All Slopes (OG)

• Custer Norma Forest All Slopes (CNF)

• Custer Norma Pasture All Slopes (CNP)

• Custer Norma Grass All Slopes (CNG)

• Saturated (Wetland) Forest All Slopes (SF)

• Saturated (Wetland) Pasture All Slopes (SP)

• Saturated (Wetland) Grass All Slopes (SG)

• Effective Impervious Surface (EIA)

TerraLogic will create SCHEMATIC blocks containing relevant acreages for use in HSPF UCIs. The numbering system assumed for use in the creation of SCHEMATIC blocks is provided in Section 8.3.

7.2 HSPF PERLND Parameters There are three possible approaches to parameter estimation, in order of preference:

• calibration to observed data (to be used on Swamp, North, and Quilceda Creeks)

• transposition of parameters from other neighboring systems (Marshlands)

• use of generalized model parameters (SW UGA, Puget Sound Drainages, Sunnyside and Allen)

X011084_3538 7.0 HSPF PERLND Definitions and Parameter Estimation 7-1 December 2002


Irrespective of the method of parameter estimation, HSPF model performance should be verified by comparing existing condition model simulation results against available water level and discharge data, including comparison of model results against documented and anecdotal reports of roadway overtopping and flooding problems. Model results should also be checked to determine whether flooding predicted by existing condition models actually occurs. In the event that the model fails to reasonably match observed conditions, the possible reasons should be explored and the model configuration and/or parameters (including FTABLEs) checked and adjusted as necessary. Model modifications that involve modifying subbasins, soils, land-use (including EIA), or slopes should be done in consultation and coordination with TerraLogic, so that the GIS coverages and data base contain all relevant corrections and modifications at the completion of the study.

Model Calibration Some level of HSPF model calibration has been accomplished in past studies on several of the streams in the study area. Model parameters from previous calibration by both the USGS and Snohomish County have been reviewed by the Hydrology Technical Lead for the following drainages:

• Swamp Creek

• North Creek

• Quilceda Creek

No detailed information is readily available on the adequacy of the most recent calibrations (performed on behalf of Snohomish County) for any of the above streams. The model parameters from the Snohomish County calibrations are reasonably close to the regional parameters developed by the USGS for Swamp and North Creeks, however the most recent Quilceda Creek model has much lower INTFW values (INTFW=1.0) than estimated by the USGS for till and Custer-Norma soils. This would increase surface runoff (SURO) from these soils types and can be expected to increase peak flows. Additionally, the previous calibrations for Swamp, North, and Quilceda had no pasture parameters and no differentiation of saturated soils by cover type. Recommended parameters for Swamp, North and Quilceda Creeks, extracted from recent model calibration files, but with pasture parameters based on comparisons with generalized parameter values, are provided in Tables 6 through 9.

A check of previous calibrations will be conducted where at least 18 months of recent concurrent streamflow and rainfall data (covering two wet seasons) are available which include one or more significant high flow events. According to information on data availability provided by the County, recent data suitable for calibration are available from three sites:

• Swamp Creek at I-405 & Magnolia

• North Creek at 240th

• West Fork Quilceda Creek at 116th

Stream flow data from other active gauges in the County are either not relevant to the current study areas or the gauges have only recently been installed.

The model parameters in Tables 6 through 9 should be used as the starting point for recalibration. Since there is no basis in the available data for discriminating between the hydrologic response of the various PERLNDs, recalibration for the current work should



consist primarily of minor adjustments to model parameters and adjustments to the effective impervious area fractions under existing land use conditions. Particular attention should however be paid to the INTFW value for Quilceda Creek (which appears to be unusually low for till and Custer-Norma soils). The exact period to be used for recalibration will be determined by the DNR team after review of the quality of available data, but should include a “reality check” of simulations for the December 1996/January 1997 flood. No specific targets for calibration accuracy are proposed.

Transposition from Other Basins In the absence of previous model calibration, HSPF parameters will be estimated by transposition from neighboring calibrated drainages as follows:

Marshlands – use North Creek parameters after calibration check

If scheduling conflicts prevent the use of calibrated North Creek parameters, then modeling of Marshlands should use generalized parameters as noted below

Generalized Model Parameters Generalized model parameters based on those developed by the USGS will be used as in Table 10 for the SW UGA, Puget Sound Drainages, Allen and Sunnyside. The following changes to the USGS generalized parameters have been made:

• slope classification (flat, moderate and steep) has been retained for till soils but the INFEXP parameters for moderate slopes is applied to flat and steep slopes also, as has been the practice in recent modeling work in Snohomish County.

• a set of pasture parameters has been added. Those shown in Table 10 are similar to those originally developed by King County and produce a hydrologic response intermediate between the forest and grass parameters.

• the USGS class of saturated soils, which originally covered all slopes and all cover types, has been further divided based on best judgment into forest, pasture and grass cover, as has been the practice in recent modeling work in Snohomish County.

• the slope length for EIA has been reduced from 500 to 100 ft.

Consideration was given to using parameters from the recent Hulbert Creek calibration for the Sunnyside system. However, this calibrated parameter set has an unusually high value for the INTFW parameter which could lead to significant underestimation of peak flows from non-outwash pervious areas.


8.0 Design and Assembly of UCIs

8.1 General The development of HSPF model UCIs will generally follow the procedures adopted by Snohomish County in previous modeling studies. Key aspects of these procedures are as follows:

• The groundwater (AGWO) component of runoff will not be routed separately from surface (SURO) and interflow (IFWO) components. All runoff generated in a subbasin will be assumed to leave that subbasin via the surface water course draining that subbasin. This assumption simplifies model assembly, and allows use of existing GIS tools for generation of SCHEMATIC blocks, but will result in unrealistic estimates of base flows, particularly on ephemeral streams on till uplands. Appropriate cautionary notes should be added to the models.

• To take advantage of existing GIS tools to generate SCHEMATIC, the final HSPF models will include both the unit area runoff simulations (PERLND/IMPLND operations) and flow routing (RCHRES operations) in a single model UCI.

Separate HSPF model UCI's will be developed for Existing and Future Land Use scenarios. All models will be run at a 15 minute time step.

8.2 Numbering of PERLND and RCHRES Operations and DSNs

A common numbering system for PERLND and RCHRES operations and for WDM DSNs should be used across DNR areas to the extent possible. The proposed numbering system is summarized in Tables 11 and 12:

Numbering of PERLND/IMPLND Operations Numbering of PERLND/IMPLND operation is summarized in Table 11. Allowance is made for up to 4 rain gages (or four different rainfall multipliers) per DNR Area. Note that Table 11 includes DSN#s for storing unit area runoff components. These are not strictly needed under the current recommendations to route all runoff components to the surface outlet of each subbasin (i.e. no separate routing of the groundwater component) and to include PERLND and RCHRES operations in a single UCI but are included to provide for possible analysis of unit area runoff data and to anticipate possible future changes in modeling strategy.

Numbering of RCHRES Operations/FTABLES Subbasins, RCHRES operations and FTABLES should be numbered identically to the extent possible (e.g. unit area runoff from subbasin 10 would be directed to RCHRES [or COPY] operation 10 with FTABLE 10). Proposed numbers are summarized in Table 12. Numbering should start from the downstream end of the system and work upward consistent with numbering systems used in the hydraulic modeling. Each subbasin or

X011084_3538 8.0 Design and Assembly of UCIs 8-1 December 2002


RCHRES should be numbered in increments of at least 2 (and preferably a greater increment) to allow for insertion of additional RCHRES operations either due to model refinements or for runs of future alternatives. The increment will be limited by the total number of reaches in the model. Reaches numbered under the existing land use scenario should retain the same numbering under the future land use alternative and under future CIP alternatives. Note that a hypothetical detention facility will be added to each subbasin with new development under the future land use scenario to represent detention facilities associated with new development – hence, the numbering increment should preferably be greater than 2 to allow for other unplanned insertions of routing elements. Note that each RCHRES may not have an associated sub-basin.

COPY Operations COPY operations should be used in place of a RCHRES on headwater subbasins where no routing element can be defined but unit area runoff need to be accumulated to provide input to a conveyance system. The numbering system for COPY operations should be the same as if a RCHRES operation were being used.

8.3 Numbering of MASS-LINK Block The recommended MASS-LINK block is provided in Table 13. MASS-LINK numbers for processing PERLND and IMPLND runoff will be supplied for each sub-basin in the sub-basin attribute file, Table 1. Defaults specified in Table 1 will be used if sub-basin specific MASS-LINK numbers are not provided.

8.4 FTABLES FTABLES for lakes, open water wetlands, regional detention facilities, and other large level-pool storages should be developed from best available stage-storage-discharge data. In the event of lack of data, an assessment should be made of the significance of the storage in terms of flow attenuation or flood damage predictions and surveys should be conducted as needed. Values in successive rows of the FTABLE must be increasing in order for HSPF to function properly (the only exception is the surface area values, which can remain constant with increasing depths). FTABLEs should also extend to high enough stages and discharges that HSPF will not attempt to extend the FTABLE range by extrapolation. The source and vintage of information for the FTABLEs should be clearly documented in comments within the HSPF UCI.

FTABLEs for wetlands are sometimes extremely difficult to establish and may require both topographic survey and collection of concurrent stage and discharge measurements.

FTABLES for open channel and closed conduit conveyance systems will be provided through the DNR team hydraulics analysis (see the DNR Hydraulic Modeling Protocols). FTABLEs developed via hydraulic analyses should be documented to show the specific hydraulic model used to create the FTABLE and the corresponding hydraulic model elements or reaches represented by the FTABLE.



8.5 Detention Ponds for Existing and Future Development

Regional detention facilities and large on-site detention facilities should be included in existing condition models to the extent that stage/storage/discharge data are readily available. The great majority of small on-site detention facilities will be ignored.

On-site detention for future development will be represented by a single detention pond in each sub-basin with new development. Allowable existing to future land use conversions were discussed in Section 3.2 and shown in Table 4. Future land use classes requiring detention are summarized in Table 3. Per input from Snohomish County Planning Department, detention for rural density residential classes will be provided for the effective impervious areas only. No detention will be provided for runoff from pervious areas for the rural residential classes. These assumptions appear to reasonably reflect current practice in which approximately 75% of new rural density residential developments are providing detention facilities

Detention ponds will be sized to meet current Title 24 performance requirements using software from Aqua Terra; PONDCN80 and POND7, both of which are available on the DNR web site. The software produces FTABLEs which can be incorporated directly into an HSPF UCI. Existing to future land use conversion data for developing input to the pond sizing routines will be provided for each sub-basin by TerraLogic. The County will be responsible for providing the software for pond sizing and supporting documentation. The DNR teams will perform actual pond sizing and FTABLE generation. Basic assumptions are summarized below:

Performance Standard Ponds will be sized for 2/0.5*2, 10/10, 100/1002 control using the SBUH method and 24-hour design storms. 24-hour design rainfall amounts will be estimated from NOAA Atlas 2. A factor of safety of 1.3 will be applied to all pond sizes (this is automatically handled by the pond sizing software POND7) except in areas of chronic flooding. Chronic flooding has been identified in the Swamp Creek basin at Russel Way between Alexander Road and Highway 99. Development upstream of this point requires the following correction factors for pond sizing:

Land Use Conversion Correction Factor

Forest to single family residential 2.5 Forest to commercial 3.7 Pasture to single family residential 2.6 Pasture to commercial 2.7

A weighted average of the above factors should be used for sizing on-site facilities in this case.

2 x/y control means control of future x-year discharges to existing y-year rate. 0.5*2 is half of the 2-year discharge.



Estimation of Target Flows For redevelopment of rural and low density residential areas, target flows for sizing detention facilities will be estimated assuming that the existing land use is forested. Otherwise the actual existing land use (forest or pasture) will be assumed. Times of concentration and curve numbers will be estimated using the approaches and guidance in Volume III of the Stormwater Management Manual for the Puget Sound Basin (Ecology, 1992). Pre- and post-development curve numbers (CNs) and times of concentration for use in pond sizing calculations (see Pond Sizing below) will be determined with AquaTerra’s PONDCN80 program using data on land-use change generated by TerraLogic. A flow path and slope are needed to estimate time of concentration. Representative existing and future condition pervious area times of concentration will be generated by PONDCN80 assuming that the area of development or redevelopment tributary to detention facilities are in 10 acre square blocks. For existing conditions, the flow path is assumed to be from one corner of the block to the mid-point of an opposing side (overland flow length of about 740 feet) with a surface slope representative of the sub-basin in question. Future pervious area times of concentration are computed in a similar fashion but assuming a reduced slope length for the pervious surface. For sub-basins with new areas of development or redevelopment less than 10 acres, then the total area under development is assumed to be in a single square block and the flow path length computed as outlined above. The future impervious area time of concentration for impervious areas is assumed to be a fixed six minutes. Sizing Procedure Detention ponds will be sized using AquaTerra’s POND7 software which is based on the SBUH method and which takes input data generated by POPNDCN80. Ponds will be sized for 80% of the development area. Land use conversion data provided by TerraLogic will be for the total converted area; adjustments to size ponds for 80% of the development area will be made automatically by PONDCN80. In HSPF simulations, 80% of the development area will be routed through the detention pond with the remaining 20% bypassing the facility. This procedure, which is slightly different from that used in previous work by the County, is intended to account for: developments which fall below threshold requirements for detention (new impervious coverage of less than 5000 sq ft); flows which bypass facilities through deviations from grading plans; facilities which fail to perform as expected because of maintenance problems; and the general tendency to minimize pond size whenever possible. The FTABLE number for each facility will be provided by the DNR team in the sub-basin attributes (Table 1). The appropriate SCHEMATIC block information will be generated by TerraLogic for inclusion in future land use HSPF models. The construction of the future land use SCEMATIC block is illustrated in Figure 1.

8.6 Rain and Evaporation from Lakes Rainfall on and evaporation from the surface of lakes will be modeled explicitly only for water bodies broken out as open water in the land use analysis.



8.7 Hydraulic Routing Stability The numerical stability of the HSPF hydraulic routing algorithms is controlled by the weighting factor KS. A value of KS = 0.5 provides the greatest accuracy providing no instabilities occur in the routing. Hydraulic instability is likely to occur when attempting to route large rapidly changing flows through relatively small storage elements. To reduce the risk of instabilities, the following KS values should be used:

Routing Element KS

Stream channel 0.3

Detention facility or lake 0.5

Representative hydrograph plots of large events should be spot checked for instabilities. A KS value of 0.5 may be used if comprehensive checks of routing stability are made.


9.0 Setting Up WDM To facilitate future use of the GENSCN software by the County, at the completion of the project all simulation results for a single DNR area will reside in a single WDM built using the most recent release of ANNIE (Version 4.0).

9.1 DSN Attributes BASE YEAR BASE YEAR should be set to 1940 to allow correct data management over the year 2000 boundary.

TOLR To minimize the size of WDMs, time series should be compressed to an appropriate tolerance by specifying a TOLR attribute as follows:

Member TOLR

RAIN 0.0 (default)

SURO, IFWO, AGWO, PERO 0.0001 inches/interval

FLOW 0.001 cfs

STAGE 0.01 ft

TSFORM FLOW and STAGE may be stored as mean values for 15 minute time-step simulations.

IDSCEN, IDLOCN, and IDCONS Appropriate values should be entered for GENSCN-related attributes at the time data sets are first built in the WDMs. Attribute definitions and possible values are as follows:

Attribute Definition Value

IDSCEN Scenario ID Observed, Current, Future, CIP_Alt#1, CIP_Alt#2

IDLOCN Location ID RCH10, RCH20, etc

IDCONS Constituent ID Flow, Stage, Rainfall, Evap

Tracy Romzek (425-388-3464 x 4569) has experience in rapidly setting up the DSN attributes for WDMs and has offered to explain the procedure she has developed to anyone who is interested.

X011084_3538 9.0 Setting Up WDM 9-1 December 2002

10.0 Analyses and Presentation of Modeling Results

10.1 Flood and Stage Frequency Analysis Flood frequency analysis will be conducted for all existing and future condition simulations at all locations with known flooding or habitat problems and at other key output points such as major stream confluences. Flood frequency analysis may be conducted with any software approved by the Hydrology Technical Lead. Analysis will be based on annual exceedance only. Possible software include SWSTAT, PKFREQ, FFA, CFA, etc. Frequency plots showing data and a fitted probability distribution will be produced and maintained in project work files for each point at which flood quantiles are to be produced. Data will be plotted using the Gringorten plotting position formula (p = (rank - 0.44)/(#obs + 0.12)). Preference should be given to fitting the data using a log-Pearson Type III distribution, however any standard distribution is acceptable (e.g. Three Parameter Log-Normal, Extreme Value Type I, etc). If a reasonable fit to the data cannot be achieved using a standard probability distribution, then a graphical fit may be used. Flood quantiles should be tabulated for the 2, 10, 25, and 100-year return periods.

Stage frequency analysis for existing and future condition simulations will be required for lakes subject to flooding. Stages for flooding in free flowing stream and pipe systems should be obtained through the hydraulic analysis. Stage frequency analysis may again be done with any software approved by the Hydrology Technical Lead. Frequency plots showing data and fitted distribution will be produced and maintained in project work files for each point at which stage quantiles are to be produced. Preference should again be given to fitting the data using a log-Pearson Type III distribution. However any standard distribution is acceptable, and if a reasonable fit to the data cannot be achieved using a standard probability distribution, then a graphical fit may be used. Stage quantiles should also be tabulated for the 2, 10, 25, and 100-year return periods.

10.2 Flow Duration Annual flow duration analysis will be conducted for all existing and future condition simulations at all locations with known flooding or habitat problems and at other key output points such as major stream confluences. Flow duration analysis may be conducted using any software approved by the Hydrology Technical Lead. Duration plots should have a linear ordinate (flows) and a logarithmic abscissa (percent time exceeded). The analysis should cover flows up to about the 10-year peak discharge with the abscissa scale covering a range from about 10-6 to 1. If HSPF is being used for this analysis, the “LEVELs” should be selected to cover the necessary range of discharges and produce a reasonably smooth curve. Duration plots will be maintained in project work files with selected plots for key points reproduced in the DNR reports.

X011084_3538 10.0 Analyses and Presentation of Modeling Results 10-1 December 2002


10.3 Flow Statistics Statistics of annual and monthly average flows (average, maximum, minimum, and standard deviation) will be tabulated for existing and future condition simulations for key output points such as major stream confluences.

10.4 Input to Habitat and Water Quality Analysis Values for the following habitat-related hydrologic metrics will be computed at HSPF model output locations to be specified by the DNR team habitat specialists. Values for the required metrics will be computed using software to be provided by nhc (WDM_METRIC) and Aqua Terra (BANKFULL).

TQmean : TQmean, as defined by Booth et al. (2001), is the percent of time that flow in a given water year exceeds the mean flow for that year. The value of TQmean will be calculated by WDM_METRIC for each year in the HSPF simulation (1949-2000), then a single value for each scenario will be determined as the mean of the 52 annual values. CVAMF: CVAMF is the coefficient of variation (standard deviation over mean) of the annual maximum flood. Booth et al. (2001) calculated this metric using the natural logs of the annual maximum flow values because of the likelihood that in natural space, there would be no values less than one standard deviation below the mean. Values of CVAMF will be computed by WDM_METRIC in both log space and natural space. Relative Stream Power: This is defined by May et al (1997) as the two-year flow divided by the average winter base flow. The two-year flow, to be provided by the DNR team as an input to WDM_METRIC, will the determined by annual frequency analysis of instantaneous peak flows (see Section 10.1). The average winter base flow will be determined by WDM_METRIC as the average of the 80 percent and 95 percent exceedance flows from a seasonal flow duration analysis for 1 November through 31 March. The winter (November – March) flow duration curve will be plotted using tabulated data generated by WDM_METRIC. Summer Low Flow Duration: A summer (May-October) flow duration curve will be plotted using tabulated data generated by WDM_METRIC. Maximum/Minimum Flows: Annual maximum and May-October minimum flows for each year will be extracted from simulation results by WDM_METRIC and tabulated. Bankfull Analysis: BANKFULL will compute the duration of time and the number of events in which flows exceed bankfull flow (or any other specified discharge rate). The bankfull flow rate is input by the user and would be determined using a hydraulic model in consultation with the hydraulic modelers. An event is considered complete when flows have dropped below the specified analysis level (e.g. the bankfull flow) and stayed below that level for more than 12 hours.



10.5 Input to Hydraulic Models Inputs to HEC-RAS for Generation of FTABLEs for Existing and Future Land Use HSPF Models HEC-RAS models will be used for HSPF FTABLE generation and, in many locations, for modeling of water surface profiles to identify flooding problems and to evaluate proposed CIPs. A description of the use of HEC-RAS to generate FTABLEs is provided in the Hydraulic Modeling Protocols. Hydrologic data (flows) are needed as input to the HEC-RAS models. The locations of hydrologic input points (i.e. location of flow changes in HEC-RAS), the specification of reaches for generation of FTABLEs, and the range of flows to be modeled with HEC-RAS should be established by the hydraulic modelers in close cooperation with the hydrologic modelers.

Initial estimates of flows and their spatial variation throughout the systems to be modeled with HEC-RAS are needed to generate FTABLEs for HSPF applications. The range of “initial” flows to be modeled with HEC-RAS should cover the full range of flows for all simulations to be performed with HSPF (i.e. for existing and future land use conditions and with CIP alternatives).

Several of the study areas have existing HSPF models (e.g. Swamp, North, Quilceda). Where previous model results, notably existing condition flood flow quantiles, are available, these should be used, prorated by drainage area as necessary, to produce initial estimates of flows at the locations of interest for HEC-RAS modeling. Since quantiles are generally only reported for relatively high flows (e.g. 2-year to 100-year peak discharges), low flows should be determined by simply scaling down by a fixed multiplier the smallest flow quantile available, assumed here to be the 2-year peak flow. To ensure that flows modeled with HEC-RAS cover the full range required for all scenarios, flow estimates should extend to 150% of the reported 100-year discharge. A minimum of ten sets of flows should be provided, uniformly distributed between 0.1*Q2 and Q100, plus 1.5* Q100 for a total of eleven sets of flows.

If the range of flows contained in the FTABLE is too small, extrapolation of FTABLEs may occur in HSPF production runs, possibly requiring additional HEC-RAS runs and repeat HSPF simulations. The range of the initial flow estimates should thus be conservatively large to avoid additional future work. The flow range recommended above should be modified as necessary at the discretion of modeling staff to provide the most reasonable definition of FTABLEs.

Where previous model results are not available, estimates of flows should be based on transposition from hydrologically similar sub-basins in other previously modeled study areas, again prorating flow estimates by drainage area. For example, initial estimates of flows for Sunnyside Creek could be based on existing estimates of flow quantiles on Hulbert Creek (from the Lake Stevens MDP).

Provision of Flows for Final HEC-RAS Modeling of Existing and Future Land Use Conditions Peak flow quantiles for 2-, 10-, 25-, and 100-year return periods for use as input to HEC-RAS models will be determined through frequency analysis (see Section 10.1) from the long-term HSPF simulations for existing and future land use scenarios and for the CIP alternatives. Locations for production of flow quantiles for HEC-RAS modeling will be determined in consultation with the hydraulic modelers.



Selection of Design Events for SWMM Modeling of Existing and Future Land Use Conditions Hydrographs are required as input to SWMM models for 2-, 10-, and 25-year events for existing and future land use conditions. The locations at which hydrographs are required should be determined in consultation with hydraulic modelers. Specific storm events representative of 2-, 10-, and 25-year conditions cannot be identified a priori - the return period of specific events depends on many factors, including land use and amount of storage in the system being modeled. Experience in previous modeling indicates that the largest 4 or 5 events (in terms of peak flow) are generally the largest 4 or 5 events throughout any system being modeled although the exact ranking of the individual events may change, especially where storage in the system significantly attenuates peak flows. Experience also suggests that an event close to a two-year event will remain close to a two-year event for a rather wide range of hydrologic and hydraulic conditions. Events for SWMM modeling will therefore be determined as follows:

• Develop hydraulic (SWMM) model for pipe system of interest.

• Run range of steady-state flows through SWMM model independent of HSPF to determine threshold flow which causes flooding and to generate FTABLEs. FTABLEs are needed for individual pipe segments and associated storage, whether in-pipe or due to flooding.

• Set up HSPF incorporating above FTABLEs and run long-term simulations for existing and future land use.

• Conduct peak flow frequency analysis and use results to determine frequency of flooding at problem locations.

• Based on peak flow frequency analysis, select as design events those events which plot most closely to the 10- and 25-year return periods. The performance standard for CIP design is to convey the 25-year peak flow. Introduction of storage as part of a CIP may however significantly affect the ranking of events. Thus, careful consideration should be given to the volume in candidate 25-year events, with more weight being given in the selection process to events with combined high peaks and volumes. Two or more events should be selected as possible candidates for the 25-year design event.

• Select an event close to the 25th ranked event as the 2-year event. Several events with peak flows close to that of the 2-year peak flow should be examined to ensure that the selected event has an appropriate combination of peak and volume.

• Final selection of the 2-, 10- and 25-year design events will be made by the DNR team and the County at the DNR area H&H Check-In Meeting.

Future versions of the protocols will address development of hydrologic inputs for use in hydraulic modeling of future CIP alternatives.


11.0 Documentation and Quality Control

11.1 Documentation The purpose of documentation will be to report study results, to provide the County with sufficient information to understand the basis for and limitations of the modeling effort, and to provide sufficient information that the models produced here can be modified or refined in the future without undue difficulty. Several levels of documentation are required:

UCI Documentation Final HSPF UCIs will contain liberal internal documentation. At a minimum the internal documentation will describe:

• the authors of the model

• the date of most recent model modifications

• the date of the most recent run used to write or update WDM information

• the name of the system being modeled

• the land use condition and/or CIP alternative (existing, future, future with CIP#1, etc) and source of land use data

• clear identification of sub-basins in the SCHEMATIC block

• clear identification of the stream reach or water body being described by each FTABLE

• information on the source of FTABLE information including, for example, reference to specific hydraulic model files that may have been used to generate information, or specific information on the survey data

• the correspondence between RCHRES operations and key physical locations in the stream system.

WDM Documentation Each DSN in the WDM should have a clear and unambiguous definition of the DSN contents through use of the STAID and STANAM attributes. A index of WDM contents should be included in the DNR report.

DNR Report The DNR Report will include an appendix documenting the hydrologic modeling effort. The outline for the DNR report is available in a separate DNR Table of Contents. The DNR Report will document or include:

• sources of land use, soils, and slope data

X011084_3538 11.0 Documentation and Quality Control 11-1 December 2002


• sources of critical area data, including wetlands

• HSPF model schematics

• the basis for (and limitations of) each model FTABLE including cross references to specific hydraulic model files used to generate FTABLE information

• an index providing correspondence between model RCHRESs, WDM DSNs, and flooding locations, locations at which HSPF model output will be used to provide input to hydraulic models, or other output locations

• documentation of model calibration or validation efforts

• a complete index of WDM contents

• all important assumptions and limitations in the model development and application

11.2 Quality Control Quality Control will be the responsibility of the DNR Lead and should include the following: 1. Check total basin and sub-basin drainage areas in existing and future models for

consistency.

2. Check existing and future land use data for accuracy by examining check plots and aerial photos to be produced by TerraLogic. Check for: conformance with defined land use classes, correct interpretation of land use for existing (1998) land use, correct interpretation of existing pervious land cover types. Also check for correct application of critical area rules as they affect future development and correct application of rules concerning allowable existing to future land use conversions.

3. Check soils and surficial geology mapping for consistency with available published information and areas of known seasonal saturation.

4. Check slope mapping for reasonableness.

5. Check rainfall data to ensure that time series do not contain unreasonably high rainfall intensities (see Section 6.0 for responsibilities for this task).

6. Check that model connectivity is correct and complete by preparing simple model schematics and comparing with real world drainage network. Schematics should show all subbasins (and total subbasin areas), and their connectivity to all routing elements in the HSPF model. The schematic should identify all points with known flooding problems for which detailed hydrologic analyses will be conducted. An example schematic is shown in Figure 2. The schematic may occupy several pages for clarity.

7. Routinely review all HSPF warning messages and modify UCIs accordingly.

8. Extend FTABLEs as necessary to eliminate extrapolation in hydraulic routing.

9. Verify and document model performance against available recorded streamflow data and anecdotal information on flooding (see Section 7.2)

10. Compare unit area hydrologic response of key PERLNDs for selected flood hydrographs for reasonableness.



11. Perform spot checks of flood hydrographs at selected locations for numerical stability.

12. Compare existing and future flood quantiles for consistency and reasonableness throughout the modeled system.

13. Review the hydrology content of the DNR Report (generally parts of DNR Report Section 4 and Appendix A) for accuracy and completeness, and for conformance to documentation standards.

If practicable, reviews will be conducted by individuals who have not been involved in the model development and application. Quality control activities will be documented in internal memos to be maintained with the project work files. A checklist for QA/QC activities is provided in Appendix B.

11.3 Archiving of Model and Results The HSPF model UCIs, WDM and DNR report sections will be archived in digital form on completion of the project. For model WDMs that can fit on a single CD-ROM (WDMs less than about 640 MB), all files will be archived and submitted to the County on CD-ROM. For WDMs which exceed the capacity of a single CD, the WDM and other files will be submitted on a DVD-ROM. In exceptional cases and with the County's approval, large WDM files may be provided on a portable hard drive, with other files on CD-ROM. A README file describing the digital files will be included on the CD-ROM or DVD-ROM and in the DNR report. Specifications for use of portable hard drives should be requested from the County if that option is to be used.


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Table 1 Sub-Basin Attributes

No. Attribute NotesDefault Value

1 Subbasin Number2 Raingage Number 1 through 4 - governs PERLND & IMPLND numbers 13 Target Name 1 RCHRES or COPY RCHRES4 Target Number 1 Operation number5 PERLND Mass-Link Number for Target 1 See Table 13 & Section 8.3 16 IMPLND Mass-Link Number for Target 1 See Table 13 & Section 8.3 47 Target Name 2 RCHRES or COPY for second operation on same

subbasin - blank if no second operation8 Target Number 2 Operation number9 PERLND Mass-Link Number for Target 2 See Table 13 & Section 8.310 IMPLND Mass-Link Number for Target 2 See Table 13 & Section 8.311 Future Detention Pond Number RCHRES operation number for detention pond for

new development within the subbasin12 EIA Table Number (Existing Land Use) See Table 2 & Section 3.413 Existing rural density residential - %

forest cover See Table 2 & Section 3.514 Existing low density residential - % forest

cover See Table 2 & Section 3.515 Future low density rural residential (1 unit

/ 20 acres) - % retention of existing forest cover See Table 3 & Section 3.5 50

16 Future rural residential -10 (1 unit / 10 acres) - % retention of existing forest

cover See Table 3 & Section 3.5 5017 Future rural residential - 5 (1 unit / 5

acres) - % retention of existing forest cover See Table 3 & Section 3.5 30

18 Future rural residential (1 unit / 5 acres Basic) - % retention of existing forest

cover See Table 3 & Section 3.5 3019 Future rural residential - 10 Resource

Transition (1 unit / 10 acres) - % retention of existing forest cover See Table 3 & Section 3.5 50

20 Target Name 3 RCHRES or COPY for routing of runoff from impervious surfaces within sub-basin

21 Target Number 3 Operation number22 IMPLND Mass-Link Number for Target 3 See Table 13 & Section 8.3



Table 2 Impervious Area Percentages By Existing Land Use

Existing #1 (EIA#1) Existing #2 (EIA#2) Existing #3 (EIA#3)Land Use Pervious Cover Gross Connected Effective Gross Connected Effective Gross Connected Effective

(with default split) Imp Imp Imp Imp Imp Imp(%) (%) (%) (%) (%) (%) (%) (%) (%)

Open Water n/a 0 0 0 0 0 0 0 0 0 Forest F 0 0 0 0 0 0 0 0 0 Pasture P 0 0 0 0 0 0 0 0 0 Grass G 0 0 0 0 0 0 0 0 0 Rural Density SFR F(50%)/P&G(50%) 1 0 0 1 0 0 1 0 0

Low Density SFRF(30%) /P&G(67% EIA#1) F(30%) /P&G(67% EIA#2) F(30%) /P&G(64% EIA#3)

15 20 3 15 20 3 20 30 6

Medium Density SFR G 25 40 10 30 60 18 40 70 28High Density SFR G 50 60 30 55 70 41.2 60 80 48Multifamily Res G 60 80 48 70 95 66.5 75 100 75Commercial G 90 95 85.5 90 95 85.5 90 100 90Roads G 70 90 63 90 95 85.5 90 95 85.5

Mulitfamily include Trailer Parks

Densities are approximately as follows: Pervious Cover Types:Rural density SFR - less than or equal to 1 unit per 5 acres F - forestLow density SFR - 0.2 to 2 units per gross acre P - pastureMedium density SFR - 2 to 6 units per gross acre G - grass or lawnHigh density SFR - > 6 units per gross acre F/P&G - mix of forest and pasture + grass with default split

P&G is assumed 80% pasture and 20% grass (lawn)

Note: For Rural and Low Density SFR, DNR teams should specify estimated percent forest cover by subbasin in subbasin attribute tables (Table 1).

Hydrologic Modeling Protocols Table 3

Future Land Use Classes and Associated Cover Pervious Cover

Future Land Use Classes Existing Use Code Percent Code Percent Gross Imp % connect EIA DetentionUndefined - Road rights of way G 14.5 90 95 85.5 YesTwo Line River W 100 0 0 0 n/aLake W 100 0 0 0 n/aPowerline Right-of-way P 100 0 0 0 NoTulalip Tribes Trust Land Incorporated City Area (Includes Water Reservoirs and Well Sites) G 52 60 80 48 YesNational Forest Land (Includes some Private and Non-federal Public Lands) F 100 0 0 0Urban Low Density Residential (4-6 Dwelling Units / Acre) G 72 40 70 28 YesUrban Medium Density Residential (6-12 Dwelling Units / Acre) G 52 60 80 48 YesUrban High Density Residential (12-24 Dwelling Units / Acre) G 25 75 100 75 YesLow Density Rural Residential (1 Dwelling unit / 20 Acres) Forest F 50 P&G 49 1 100 1 Yes" Non Forest F tbd P&G tbd 1 100 1 YesRural Residential - 10 (1 Dwelling Unit / 10 Acres) Forest F 50 P&G 48 2 100 2 Yes" Non Forest F tbd P&G tbd 2 100 2 YesRural Residential - 5 (1 Dwelling Unit / 5 Acres) Forest F 30 P&G 66 4 100 4 Yes" Non Forest F tbd P&G tbd 4 100 4 YesRural Residential (1 Dwelling Unit / 5 Acres Basic) Forest F 30 P&G 66 4 100 4 Yes" Non Forest F tbd P&G tbd 4 100 4 YesRural Residential - RD (1 Dwelling Unit / 2.3 Acres) " Rural Residential - 10 Resource Transition (1 Dwelling Unit / 10 Acres) Forest F 50 P&G 48 2 100 2 Yes" Non Forest F tbd P&G tbd 2 100 2 YesUrban Commercial G 10 90 100 90 YesUrban Industrial G 10 90 100 90 YesRural Commercial G 10 90 100 90 YesRural Industrial G 10 90 100 90 YesLocal Commercial Farmland P 100 0 0 0 NoUpland Commercial Farmland P 100 0 0 0 NoRiverway Commercial Farmland P 100 0 0 0 NoCommercial Forest F 100 0 0 0 NoLocal Forest (Tulalip Only) F 100 0 0 0 NoForest Transition Area F 100 0 0 0 NoOther Land Use (Outside Urban Growth Area) Other Land Use (Inside Urban Growth Area) - Marshland UGA P 80 20 100 20 Yes - Sunnyside Creek G 72 40 70 28 Yes - Quilceda East of I5 P 100 0 0 0 No - Quilceda West of I5 G 52 60 80 48 Yes - Swamp Creek F 100 0 0 0 NoRural Freeway Service G 14.5 90 95 85.5 YesUrban Low Density Res - Limited (4-5 Units/Acre) (Marysville UGA) G 72 40 70 28 YesUrban Low Density Res. - Limited (5-6 Units/Acre) (Marysville UGA) G 72 40 70 28 YesPublic Use (assumed to be school sites) (Marysville & Mill Creek UGAs) G 50 50 100 50 YesParks/Open Space (Arlington and Snohomish UGAs ) F 50 P 50 0 0 0 NoUrban Horticulture (Snohomish UGA) P 100 0 0 0 No

Note: The study area includes no land in the following classes: Possible Veg Codes: F Forest W Water - Tulalip Tribes Trust Land P Pasture P&G Pasture and grass (80% / 20% split) - Rural Residential - RD (1 unit / 2.3 acres) G Grass/Lawn - Other Land Use (Outside UGA) tbd To be determined from existing cover via GIS analysis (see Section 3.5 and Table 1)

Hydrologic Modeling Protocols Table 4

Allowable Existing to Future Land Use Conversions

Existing Land Use

O

pen

Wat

er

Fo

rest

Pa

stur

e

G

rass

Ru

ral D

ensit

y SF

R

Low

Dens

ity S

FR

Med

ium

Den

sity

SFR

High

Den

sity

SFR

Mul

tifam

ily R

es

Com

mer

cial

Road

s

Future Land Use ClassUndefined - Road rights of way Y Y Y YTwo Line RiverLakePowerline Right-of-way Tulalip Tribes Trust LandIncorporated City Area (Includes W ater Reservoirs and Well Sites) Y Y Y YNational Forest Land (Includes some Private and Non-federal Public Lands) Urban Low Density Residential (4-6 Dwelling Units / Acre) Y Y Y YUrban Medium Density Residential (6-12 Dwelling Units / Acre) Y Y Y YUrban High Density Residential (12-24 Dwelling Units / Acre) Y Y Y YLow Density Rural Residential (1 Dwelling unit / 20 Acres) Y Y Rural Residential - 10 (1 Dwelling Unit / 10 Acres) Y Y YRural Residential - 5 (1 Dwelling Unit / 5 Acres) Y Y YRural Residential (1 Dwelling Unit / 5 Acres Basic) Y Y YRural Residential - RD (1 Dwelling Unit / 2.3 Acres) Y Y YRural Residential - 10 Resource Transition (1 Dwelling Unit / 10 Acres) Y Y YUrban Commercial Y Y Y YUrban Industrial Y Y Y YRural Commercial Y Y Y YRural Industrial Y Y Y YLocal Commercial Farmland Y Upland Commercial Farmland Y Riverway Commercial Farmland Y Commercial Forest Local Forest (Tulalip Only) Forest Transition Area Other Land Use (Outside Urban Growth Area)Other Land Use (Inside Urban Growth Area) - Marshland UGA Y Y Y - Sunnyside Creek Y Y Y Y - Quilceda East of I5 - Quilceda West of I5 Y Y Y Y - Swamp CreekRural Freeway Service Y Y Y YUrban Low Density Res - Limited (4-5 Units/Acre) (Marysville UGA) Y Y Y YUrban Low Density Res. - Limited (5-6 Units/Acre) (Marysville UGA) Y Y Y YPublic Use (assumed to be school sites) (Marysville & Mill Creek UGAs) Y Y Y YParks/Open Space (Arlington and Snohomish UGAs ) Y YUrban Horticulture (Snohomish UGA)


Table 5 Soil Types and HSPF Classification

Soil Type HSPF Classification

ALDERWOOD TillBELLINGHAM SaturatedBELLINGHAM VARIANT SaturatedCATHCART TillCUSTER Custer-Norma

EVERETT OutwashFLUVAQUENTS SaturatedINDIANOLA OutwashKITSAP TillLYNNWOOD Outwash

MCKENNA TillMUKILTEO SaturatedNARGAR OutwashNARGAR VARIANT OutwashNORMA Custer-Norma

NORMA VARIANT Custer-NormaPASTIK TillPILCHUCK OutwashPITS OutwashPUGET Saturated

PUYALLUP OutwashRAGNAR OutwashRIVERWASH OutwashSNOHOMISH SaturatedSULTAN Custer-Norma

SUMAS SaturatedTERRIC MEDISAPRISTS SaturatedTOKUL TillURBAN LAND ImperviousWINSTON Outwash



Table 6Swamp Creek (excl. Scriber) HSPF Model Parameters (extended from calibrated set)

Land Segment

LZSN (in.)

INFILT (in/hr)

LSUR (ft.)

SLSUR KVARY (1/in.)

AGWRC (1/day)

INFEXP INFILD BASETP AGWETP CEPSC (in)

UZSN (in)

NSUR INTFW IRC (1/day)

LZETP RETSC (in)

TFF 5.5 0.08 400 0.05 0.5 0.996 3.5 2.0 0.0 0.15 0.2 1.00 0.35 3.0 0.7 0.90 n/aTFM 5.5 0.08 400 0.11 0.5 0.996 2.0 2.0 0.0 0.15 0.2 0.50 0.35 6.0 0.5 0.90 n/aTFS 5.5 0.08 200 0.20 0.5 0.996 1.5 2.0 0.0 0.15 0.2 0.30 0.35 7.0 0.3 0.90 n/a

TPF 5.5 0.06 400 0.05 0.5 0.996 3.5 2.0 0.0 0.05 0.1 0.60 0.30 3.0 0.7 0.45 n/aTPM 5.5 0.06 400 0.11 0.5 0.996 2.0 2.0 0.0 0.05 0.1 0.30 0.30 6.0 0.5 0.45 n/aTPS 5.5 0.06 200 0.20 0.5 0.996 1.5 2.0 0.0 0.05 0.1 0.20 0.30 7.0 0.3 0.45 n/a

TGF 5.5 0.03 400 0.05 0.5 0.996 3.5 2.0 0.0 0.05 0.1 0.50 0.25 3.0 0.7 0.45 n/aTGM 5.5 0.03 400 0.11 0.5 0.996 2.0 2.0 0.0 0.05 0.1 0.25 0.25 6.0 0.5 0.45 n/aTGS 5.5 0.03 200 0.20 0.5 0.996 1.5 2.0 0.0 0.05 0.1 0.15 0.25 7.0 0.3 0.45 n/a

OF 6.0 2.00 400 0.05 0.3 0.996 2.0 2.0 0.0 0.15 0.2 0.50 0.35 0.0 0.7 0.90 n/aOP 6.0 1.40 400 0.05 0.3 0.996 2.0 2.0 0.0 0.05 0.1 0.50 0.30 0.0 0.7 0.45 n/aOG 6.0 0.80 400 0.05 0.3 0.996 2.0 2.0 0.0 0.05 0.1 0.50 0.25 0.0 0.7 0.45 n/a

CNF 2.0 0.40 400 0.01 4.0 0.990 3.5 2.0 0.0 0.15 0.2 1.00 0.35 4.0 0.8 0.90 n/aCNP 2.0 0.30 400 0.01 4.0 0.990 3.5 2.0 0.0 0.05 0.1 0.70 0.30 4.0 0.8 0.90 n/aCNG 2.0 0.16 400 0.01 4.0 0.990 3.5 2.0 0.0 0.05 0.1 0.50 0.25 4.0 0.8 0.90 n/a

SATF 5.0 2.00 100 0.001 0.5 0.996 10.0 2.0 0.0 0.70 0.2 3.00 0.50 1.0 0.7 0.99 n/aSATP 5.0 1.80 100 0.001 0.5 0.996 10.0 2.0 0.0 0.70 0.1 3.00 0.50 1.0 0.7 0.99 n/aSATG 5.0 1.00 100 0.001 0.5 0.996 10.0 2.0 0.0 0.70 0.1 3.00 0.50 1.0 0.7 0.99 n/a

EIA n/a n/a 100 0.010 n/a n/a n/a n/a n/a n/a n/a n/a 0.10 n/a n/a n/a 0.10

HSPF Model Parameter


Table 7Scriber Creek HSPF Model Parameters (extended from calibrated set)

Land Segment

LZSN (in.)

INFILT (in/hr)

LSUR (ft.)

SLSUR KVARY (1/in.)

AGWRC (1/day)


UZSN (in)


LZETP RETSC (in)




OF 5.0 2.00 400 0.05 0.3 0.990 2.0 2.0 0.0 0.08 0.2 0.50 0.35 0.0 0.7 0.70 n/aOP 5.0 1.40 400 0.05 0.3 0.990 2.0 2.0 0.0 0.08 0.1 0.50 0.30 0.0 0.7 0.25 n/aOG 5.0 0.80 400 0.05 0.3 0.990 2.0 2.0 0.0 0.08 0.1 0.50 0.25 0.0 0.7 0.25 n/a






Table 8North Creek HSPF Model Parameters (extended from calibrated set)

Land Segment

LZSN (in.)

INFILT (in/hr)

LSUR (ft.)

SLSUR KVARY (1/in.)

AGWRC (1/day)


UZSN (in)


LZETP RETSC (in)




OF 5.0 2.00 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.2 0.50 0.35 0.0 0.7 0.70 n/aOP 5.0 1.40 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.1 0.50 0.30 0.0 0.7 0.25 n/aOG 5.0 0.80 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.1 0.50 0.25 0.0 0.7 0.25 n/a






Table 9Quilceda Creek HSPF Model Parameters (extended from calibrated set)

Land Segment

LZSN (in.)

INFILT (in/hr)

LSUR (ft.)

SLSUR KVARY (1/in.)

AGWRC (1/day)


UZSN (in)


LZETP RETSC (in)




OF 5.0 2.00 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.2 0.50 0.35 0.0 0.7 0.70 n/aOP 5.0 1.40 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.1 0.50 0.30 0.0 0.7 0.25 n/aOG 5.0 0.80 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.1 0.50 0.25 0.0 0.7 0.25 n/a






Table 10Generalized HSPF Model Parameters (adapted from Dinicola, 1990)

Land Segment

LZSN (in.)

INFILT (in/hr)

LSUR (ft.)

SLSUR KVARY (1/in.)

AGWRC (1/day)


UZSN (in)


LZETP RETSC (in)




OF 5.0 2.00 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.2 0.50 0.35 0.0 0.7 0.70 n/aOP 5.0 1.40 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.1 0.50 0.30 0.0 0.7 0.25 n/aOG 5.0 0.80 400 0.05 0.3 0.996 2.0 2.0 0.0 0.0 0.1 0.50 0.25 0.0 0.7 0.25 n/a






PERLND/IMPLND MEMBER PERLND/IMPLND Operation Number WDM DSN# Notes

1 PREC (Everett) 112 PREC (Silver Lake) 123 PREC (Alderwood) 134 PREC (Soper Hill) 145 PREC (Smokey Point) 156 EVAP 21

Runoff data for RAINGAGE1 100-2837 SURO RAINGAGE#1/EIA 100 100 1

8 SURO, IFWO, AGWO,PERO RAINGAGE#1/TFF 110 110,111,112,113 19 SURO, IFWO, AGWO,PERO RAINGAGE#1/TFM 120 120,121,122,123 1

10 SURO, IFWO, AGWO,PERO RAINGAGE#1/TFS 130 130,131,132,133 1

11 SURO, IFWO, AGWO,PERO RAINGAGE#1/TPF 140 140,141,142,143 112 SURO, IFWO, AGWO,PERO RAINGAGE#1/TPM 150 150,151,152,153 113 SURO, IFWO, AGWO,PERO RAINGAGE#1/TPS 160 160,161,162,163 1

14 SURO, IFWO, AGWO,PERO RAINGAGE#1/TGF 170 170,171,172,173 115 SURO, IFWO, AGWO,PERO RAINGAGE#1/TGM 180 180,181,182,183 116 SURO, IFWO, AGWO,PERO RAINGAGE#1/TGS 190 190,191,192,193 1

17 SURO, IFWO, AGWO,PERO RAINGAGE#1/OF 200 200,201,202,203 1,218 SURO, IFWO, AGWO,PERO RAINGAGE#1/OP 210 210,211,212,213 1,219 SURO, IFWO, AGWO,PERO RAINGAGE#1/OG 220 220,221,222,223 1,2

20 SURO, IFWO, AGWO,PERO RAINGAGE#1/CNF 230 230,231,232,233 121 SURO, IFWO, AGWO,PERO RAINGAGE#1/CNP 240 240,241,242,243 122 SURO, IFWO, AGWO,PERO RAINGAGE#1/CNG 250 250,251,252,253 1

23 SURO, IFWO, AGWO,PERO RAINGAGE#1/SATF 260 260,261,262,263 124 SURO, IFWO, AGWO,PERO RAINGAGE#1/SATP 270 270,271,272,273 125 SURO, IFWO, AGWO,PERO RAINGAGE#1/SATG 280 280,281,282,283 1

26 Runoff data for RAINGAGE2 300-480 300-483 127 Runoff data for RAINGAGE3 500-680 500-683 128 Runoff data for RAINGAGE4 700-880 700-883 1

Notes:1 Under the current recommendations, there would be no need to actually store unit area runoff amounts

in the WDM and hence no need to build DSNs. DSN numbers are only provided for completeness and to provide for possible future changes in modeling strategy.

2 Outwash soils will generally not have an interflow response. If INTFW = 0, then DSNs for interflow (IFWO) on outwash soils can be ignored.

Table 11PERLND/IMPLND Numbering



RCHRES/COPY Operation Number FTABLE# MEMBER WDM DSN# Notes

1 10 to 990 by INC 10 to 990 by INC FLOW/Existing conditions 1010-1990 by INC 12 STAGE/Existing conditions 2010-2990 by INC 1

3 10 to 990 by INC FLOW/Future Alt# 1 3010-3990 by INC 14 STAGE/Future Alt#1 4010-4990 by INC 1

5 10 to 990 by INC FLOW/Future Alt# 2 5010-5990 by INC 16 STAGE/Future Alt#2 6010-6990 by INC 1

Notes:1 INC should be between 2 and 10 depending on the total number of RCHRES/COPY operations

in the system being modeled. Allowance should be made for the inclusion in future land use UCIs of one additional detention facility in each subbasin where new development may occur.

RCHRES/COPY Numbering and Associated DSN NumberingTable 12



Table 13 MASS-LINK Block

MASS-LINK <Volume> <-Grp> <-Member-><--Mult--> <Target> <-Grp> <-Member->***

me> # #<-factor-> <Name> <Name> # #*** <Name> <Na MASS-LINK 1 conversion from acre-inches to acre-ft (1/12) ***

O 0.0833333 RCHRES INFLOW IVOL PERLND PWATER PER END MASS-LINK 1 MASS-LINK 2 PERLND PWATER SURO 0.0833333 RCHRES INFLOW IVOL

O 0.0833333 RCHRES INFLOW IVOL PERLND PWATER IFW END MASS-LINK 2 MASS-LINK 3

O 0.0833333 RCHRES INFLOW IVOL PERLND PWATER AGW END MASS-LINK 3 MASS-LINK 4

O 0.0833333 RCHRES INFLOW IVOL IMPLND IWATER SUR END MASS-LINK 4 MASS-LINK 5

RCHRES INFLOW RCHRES ROFLOW END MASS-LINK 5 MASS-LINK 6

L 1 RCHRES INFLOW IVOL RCHRES OFLOW OVO END MASS-LINK 6 MASS-LINK 7

L 2 RCHRES INFLOW IVOL RCHRES OFLOW OVO END MASS-LINK 7 MASS-LINK 8

N RCHRES INFLOW IVOL COPY OUTPUT MEA END MASS-LINK 8 MASS-LINK 11

O 0.0833333 COPY INPUT MEAN PERLND PWATER PER END MASS-LINK 11 MASS-LINK 12 PERLND PWATER SURO 0.0833333 COPY INPUT MEAN

O 0.0833333 COPY INPUT MEAN PERLND PWATER IFW END MASS-LINK 12 MASS-LINK 13 PERLND PWATER AGWO 0.0833333 COPY INPUT MEAN

11.4 END MASS-LINK 13

MASS-LINK 14

O 0.0833333 COPY INPUT MEAN IMPLND IWATER SUR END MASS-LINK 14 MASS-LINK 15

COPY INPUT MEAN RCHRES ROFLOW END MASS-LINK 15 MASS-LINK 16

L 1 COPY INPUT MEAN RCHRES OFLOW OVO END MASS-LINK 16 MASS-LINK 17

L 2 COPY INPUT MEAN RCHRES OFLOW OVO END MASS-LINK 17 MASS-LINK 20

N COPY INPUT MEAN COPY OUTPUT MEA END MASS-LINK 20

11.5 END MASS-LINK


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APPENDIX A

Critical Area Definitionsand ESA Buffers

A. DNR Critical Areas and ESA Buffers Critical areas and their buffers and setbacks will be protected from new future development as per critical area ordinances. Detailed assumptions regarding future land use within critical areas and their buffers and setbacks are described in Sections 3.2 and 3.3 of the main body of this document. This Appendix provides the critical area and buffer definitions assumed for the future land use analyses. Stream Buffers: Criteria from Critical Areas Ordinance (CAO): Water Type 1 2 3 4 5

Channel Width N/A 20 ft. or greater between ordinary high water marks (OHWM)

Anadromous fish: 5 ft. or wider between OHWM. Resident game fish: 10 ft. or wider between OHWM.

2 ft. wider between OHWM.

Less than 2 ft. between OHWM.

Gradient N/A Less than 4% (less than 5% for off-channel drainages)

Anadromous fish: Less than 12%. Not upstream of a falls greater than 10 ft. high. Resident game fish: Less than 12%.

N/A N/A

Flow N/A N/A Anadromous fish: N/A. Resident game fish: greater than 0.3 CFS at summer low flow.

N/A N/A

Impoundment N/A Water surface area of 1 acre or greater at seasonal low flow.

Anadromous fish: surface area less than 1 acre at seasonal low flow. Resident game fish: surface area less than 0.5 acre at seasonal low

N/A N/A

Fisheries N/A Used by substantial numbers of anadromous or resident game fish for spawning, rearing or migration.

Used by significant numbers of anadromous or resident game fish for spawning, rearing or migration.

Not used by significant numbers of fish.

Not used by significant numbers of fish.

Diversion N/A

Domestic use for 100 or more residences or campsites, accommodation facility for 100 or more persons - includes upstream reach of 1500 ft. or until the drainage area is < or = to 50%, whichever is less.

Domestic use for 10 or more residences of campsites, accommodation facility for 10 or more persons - includes upstream reach of 1,500 ft. or until the drainage area is less than 50%, whichever is less.

N/A N/A

Other All water within OHWM inventoried as "Shorelines of the State" excluding related wetlands.

Streams flowing through campgrounds available to the public having 30 campsites or more.

Contributes > 20% of the flow to a Type 1 or 2 Water. Anadromous fish impoundments have outlet to stream with anadromous fish.

All natural waters not classified as Type 1, 2 or 3, and for the purpose of protecting downstream waters

All natural waters not classified as Type 1, 2, 3 or 4, or seepage areas, ponds, and drainageways having short runoff periods

X011084_3538 A. Critical Area Definitions and ESA Buffers A-1 December 2002


Standard Buffer width Requirements (STREAMS) Widths for required rural stream buffers are as follows: (a) For a Type 1 stream--100 feet; (b) For a Type 2 stream--100 feet; (c) For a Type 3 stream--100 feet; (d) For a Type 4 stream--50 feet; and (e) For a Type 5 stream--25 feet. Widths for required urban stream buffers are as follows: (a) For a Type 1 stream--100 feet; (b) For a Type 2 stream--100 feet; (c) For a Type 3 stream--100 feet--with anadromous fish For a type 3 stream --50 feet--without anadromous fish; (d) For a Type 4 stream--25 feet; and (e) For a Type 5 stream--10 feet

DNR Stream Buffers

Data Source: County WTRCRS Coverage Stream Types 1,2,3 100ft buffer. Stream Types 4,5,9 25ft buffer.

Wetlands Buffers: Criteria from CAO: All determinations of wetlands ratings will be based on the entire extent of the wetlands, unrelated to property lines or ownership patterns. Wetlands are classified based on the following systems: (a) Category 1 wetlands are wetlands which satisfy one or more of the following criteria:

(i) Are equal to or greater than 10 acres in size, hydrologically connected and contain three or more wetland classes each covering 10 percent or more of the wetland, one of which is open water;

(ii) Have been documented by the State Department of Fish and Wildlife priority habitat species program as regionally significant waterfowl or shorebird concentration areas;

(iii) Are bog/fen systems one acre or larger; (iv) Are mature forested wetlands equal to or greater than 10 acres in size; or (v) Are estuarine wetlands.

(b) Category 2 wetlands are wetlands which satisfy one or more of the following criteria: (i) Are equal to or greater than five acres in size and contain three or more wetland classes; or (ii) Are mature forested wetlands less than 10 acres in size; (iii) Are bog/fen systems less than one acre. (c) Category 3 wetlands are wetlands which satisfy none of the criteria for Category 1, 2 or 4 wetlands. (d) Category 4 wetlands are non-riparian wetlands less than one acre, with one wetland class, and >90 percent areal coverage of any combination of species from the list in Table 2 below:

Standard Buffer Width Requirements (WETLANDS) Widths for required rural wetland buffers are as follows: (a) For a Category 1 wetlands--100 feet;



(b) For a Category 2 wetlands--75 feet; (c) For a Category 3 wetlands--50 feet; and (d) For a Category 4 wetlands--25 feet of undisturbed native vegetation, or any lesser width or vegetation type which will provide the same level of protection to the functional values of the wetland and the buffer. Widths for required urban wetland buffers are as follows: (a) For a Category 1 wetlands--75 feet; (b) For a Category 2 wetlands--50 feet; (c) For a Category 3 wetlands--25 feet; and (d) For a Category 4 wetlands--25 feet of undisturbed native vegetation, or any lesser width or vegetation type which will provide the same level of protection to the functional values of the wetland and the buffer. (5) Measurement. For streams and wetlands, the buffer shall be measured horizontally in a landward direction from the ordinary high water mark or wetland edge, respectively. Where lands adjacent to a stream display a continuous slope of 33 percent or greater, the buffer shall include such sloping areas. Where the horizontal distance of the sloping area is greater than the required standard buffer, the buffer shall be extended to a point 25 feet beyond the top of the bank of the sloping area.

DNR Wetland Buffers

Data Source: PDS and SWM Updated Wetlands Coverage 50ft buffer on all wetlands Landslide Hazard/Critical Slope areas: Criteria from CAO: Structures on, or adjacent to, landslide hazard areas shall be protected by use of generally accepted proper engineering and construction practices, and shall meet the following requirements: (a) Ascending Slopes. For slopes 33 percent to 100 percent, the setback from the toe of the slope shall be the height of the slope divided by 2. For slopes greater than 100 percent, the setback from the toe of the slope shall be the height of the slope divided by 2. The toe of the slope shall be assumed to be at the intersection of a horizontal plane drawn at the top of the foundation and a plane drawn tangent to the slope at an angle of 45 (100 percent) to the horizontal. (b) Descending Slopes. For slopes 33 percent to 100 percent, the setback from the top of slope shall be the height of the slope divided by 3. For slopes greater than 100 percent, the required setback from the top of the slope shall be the height of the slope divided by 3. The setback shall be measured from an imaginary plane 45 (100 percent) to the horizontal projected upward from the toe of the slope.

DNR Steep Slopes Buffers Data Source: Snohomish County 10m DEM Select 40% slopes or greater For each steep slope area calculate average slope height Buffer steep slope polygon by height / 3 Salmonid Recovery Planning Guidelines: The Primary Association Area shall include all documented and presumed aquatic habitat areas for Bull Trout and Chinook Salmon species. Presumed aquatic habitat shall be defined as all aquatic habitat that meets the minimum physical parameters necessary to support Bull Trout and Chinook species during any life history stage. Presumed aquatic habitat is used



under this rule rather than known distribution because the absence of documentation of use by the targeted species or the species’ absence during the period of sampling does not necessarily mean that the aquatic habitat is not used by the subject listed species. Adjacent riparian environments shall be defined as those lands within 150 feet horizontally of the ordinary high water mark (OHWM) of all documented and presumed aquatic habitat of Bull Trout and Chinook species.

DNR Bull Trout and Chinook Salmon Habitat Buffers Data Source: County Chinook and Bulltrout Distribution Coverages County WTRCRS Coverage 150 ft buffer on Chinook and Bulltrout Distribution 150 ft buffer on Shoreline from WTRCRS Coverage


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APPENDIX B

Hydrologic ModelingQA/QC Checklist

Hydrologic Modeling QA/QC Checklist

Shaded area means not applicable

Mapping and Data

Products

Existing Land-Use

Model Future Land-Use Model

Future Land-Use Model - CIP Alt #1


Issue Y N Y N Y N Y N Y N

1 Does existing land use mapping conform with defined land use classes?

2 Is existing land-use mapping interpreted correctly for 1998 land use?

3 Is interpretation of existing pervious cover types correct? 4 Have critical area rules been correctly applied in

determining future land use? 5 Have rules governing allowable existing to future land use

conversions been correctly applied? 6 Is soils and surficial geology mapping consistent with

available information and areas of seasonal saturation? 7 Is land surface slope mapping reasonable? 8 Are peak rainfall intensities reasonable? 9 Does the sum of PERLND and IMPLND areas, plus any

surface water area, equal the total subbasin area for each subbasin?

10 Are total basin and sub-basin drainage areas consistent in existing and future models?

11 Does the model schematic correctly and completely reflect the model UCI?

12 Does the model schematic correctly reflect the real-world drainage system?

13 Does the model correctly account for areas draining to or bypassing future on-site detention facilities?

14 Do the HSPF model FTABLEs reflect the correct real-world storage locations and reach lengths (requires coordination with hydraulic modelers)?

Hydrologic Modeling QA/QC Checklist

Shaded area means not applicable

Mapping and Data

Products

Existing Land-Use

Model Future Land-Use Model



Issue Y N Y N Y N Y N Y N

15 Are the FTABLEs fully and accurately documented in the HSPF model

16 Have model error and warning messages been reviewed and necessary corrective actions been taken?

17 Have all HSPF extrapolations of FTABLEs been corrected?

18 Has model performance been verified against recorded streamflow data and anecdotal reports of flooding?

19 Are the unit area hydrologic responses of key PERLNDs reasonable during major floods and consistent with expectations?

20 Do simulated flows show any evidence of model instability?

21 Are flood quantiles consistent and reasonable throughout the system?

22 Is the timing (date/season) of simulated annual floods consistent with expectations?

Volume II Snohomish County

Drainage Needs Report Hydraulic Modeling Protocol

�� Public Works

Surface Water Management Division 2731 Wetmore Avenue, 2nd Floor

Everett, WA 98201 425-388-3464

Contents Page

Foreword

HEC-RAS Model...................................................................................................1-1 Topographic Map and System Schematic..........................................................1-1 File Management................................................................................................1-1 Geometry Files ...................................................................................................1-2

Identifying Streams and Reaches...........................................................1-2 Entering Cross-Section Data ..................................................................1-2 Modeling Bridges and Culverts...............................................................1-6

Steady Flow Files ...............................................................................................1-9 Boundary Conditions ..............................................................................1-9 Naming Conventions for Profiles and Flow Change Locations ............1-10

Plan Files..........................................................................................................1-10 Modeling Approach...............................................................................1-10 Flow Regime Selection.........................................................................1-10

Using HEC-RAS to Create FTABLEs...............................................................1-10 HEC-RAS Results Documentation .......................................................1-13

EPA-SWMM Model...............................................................................................2-1

Data Requirements ............................................................................................2-1 Model Development ...........................................................................................2-2 Naming Convention............................................................................................2-3

Node Naming Convention (Catchbasins, Manholes, Inlets) ...................2-3 Conveyance Naming Convention (Pipes, Ditches, Channels) ...............2-3 File Naming Convention .........................................................................2-4

Using SWMM for FTABLE Generation...............................................................2-4

General Considerations .....................................................................................3-1 Use of Other Models ..........................................................................................3-1 Model Result Presentation .................................................................................3-1 Quality Assurance/Quality Control .....................................................................3-2

X011084_3538 Contents iii December 2002

Hydraulic Modeling Protocol

Figures Page

1 Reach and Cross-Section Identification Convention ..........................................1-3 2 Cross-Section Editor ..........................................................................................1-4 3 Methods for Cross-Section Interpolation ............................................................1-5 4 Bridge Modeling Approach Editor.......................................................................1-7 5 Typical FTABLE Format ...................................................................................1-12

Tables Page

1 Computation Methods for Bridges......................................................................1-8 2 Naming Convention Codes for DNR Areas and Subareas.................................2-5 3 Naming Convention Codes for Flood Events, Conditions, and Extensions........2-6 4 Hydraulic Modeling QA/QC Checklist.................................................................3-2

X011084_3538 Contents iv December 2002

FOREWORD This document presents protocols to be used when conducting hydraulic modeling for the Snohomish County Department of Public Works. The protocols have been developed to provide a consistent approach to hydraulic modeling tasks conducted by various teams during the Snohomish County Drainage Needs Report (DNR) project. Topics covered include file management, naming conventions, modeling approaches, methods and documentation.

X011084_3538 FOREWORD December 2002

HEC-RAS MODEL HEC-RAS (Hydrologic Engineering Center’s River Analysis System) is a software package that calculates water surface profiles using one-dimensional steady or unsteady-flow analysis. The steady flow option of HEC-RAS 3.0 will be used on the DNR project and may be downloaded from http://www.wrc-hec.usace.army.mil/. Development of a HEC-RAS model requires flow data as well as geometric data such as surveyed cross-sections, in-stream and overbank n-values, and information on each bridge, culvert, or other hydraulic structure in the study area. The locations of significant obstructions such as buildings, debris piles etc. should also be surveyed so they may be represented in the model.

Topographic Map and System Schematic Model users should work from the best available topographic map and should use the following guidelines in developing the model:

• On the topographic map, mark locations of cross-sections, stream junctions, hydraulic structures, and significant in-stream or overbank obstructions (i.e., buildings, levees).

• Align cross-sections perpendicular to the direction of flow. Where overbank flow directions are different from the in-stream flow direction, overbank segments should be rotated accordingly (using the edge-of-channel points as the axis of rotation).

• Assign County survey identifiers to each cross-section, starting downstream and working upstream.

• Where surveyed cross-sections need to be extended beyond survey limits to cover the entire floodplain, use the best available topographic information to estimate new stations and elevations. Cross-sections should be extended to the limits of the floodplain to ensure correct calculation of floodplain storage. In general, the County’s 20-foot contours will not be sufficiently accurate for extending cross-sections.

File Management Since each HEC-RAS project file will have multiple associated geometry, flow, and plan files, clear and consistent naming conventions are essential. Self-explanatory titles are much easier to keep track of than numbers when multiple scenarios are being analyzed. Also keep in mind that profile and cross-section plots can be labeled with the plan and profile name specified under the file. The following file naming conventions should be followed when setting up new projects or entering new data:

X011084_3538 HEC-RAS MODEL 1-1 December 2002


• Project File—Use easily recognizable titles and short identifiers, such as the name of the DNR stream or general area within the stream. The following are example titles with corresponding short identifiers in parentheses:

− Upper Little Bear (ULBear) − Little Bear RM 2.0 – RM 3.0 (LBearRM2_3)

• Geometry Files—Geometry files should be named to represent either existing conditions or proposed project improvements; for example:

− Existing Conditions − Alt 1 – Replace Undersized Culverts

• Steady Flow File—Flow files should be named to represent the flow condition used; for example:

− FTABLE Flows (stage-storage-discharge-surface area relationships) − Existing Flows − Future Flows

• Plan File—The plan file, like the project file, has both a title and a short identifier and identifies existing or future conditions. The following are example titles with corresponding short identifiers in parentheses:

− FTABLE Run (FTABLE) − Existing Conditions (Existing) − Future Flows, No Improvements (Future) − Alt 1, Replace Culverts (Alt 1) − Alt 2, Regional Detention (Alt 2)

Geometry Files

Identifying Streams and Reaches When setting up a new geometry file and creating a schematic of the stream, stream and reach names and identifiers should correlate to the stream name and numbering schemes provided on the County’s GIS maps wherever possible, including the use of the WRIA ID number when available. Where unidentified tributaries intersect the stream, the tributaries should be named accordingly, e.g., “Unnamed Tributary 1.”

Entering Cross-Section Data

Identifying Cross-Sections In HEC-RAS, cross-sections start with the lowest number for the furthest downstream cross-section, as shown in Figure 1. This also applies to intersecting tributaries.



Figure 1. Reach and Cross-Section Identification Convention The section numbers for each cross-section should be referenced as the distance (in feet) along the main channel from the furthest downstream cross-section. For tributaries, the cross-sections will be referenced to the furthest downstream cross-section of the tributary. The user should use the description entry in the “Cross-Section Data” window (Figure 2) to indicate the survey identifier as well as any relevant landmark description (such as “upstream of Sunnyside Boulevard”). If a cross-section is used that was not a surveyed cross-section, then the description entry also should identify its source, such as “interpolated,” “from topographic map,” “copy of CS1234,” etc. Junctions are to be labeled with a “J” and the distance in feet upstream of the furthest downstream cross-section (i.e., J2055).

Cross-Section Base Geometry Cross-section stationing is always oriented from left to right looking in the downstream direction. The starting station point for each cross-section will be zero at the furthest left point of the cross-section (HEC-RAS does allow negative numbers if you have to add on points from a topographic map later to widen the cross-section). Station numbers must increase from left to right. Two points may have the same station (i.e., a vertical slope or wall). Elevations for all cross-sections will be referenced to the standard project datum.



Figure 2. Cross-Section Editor Data required for each cross-section includes the following:

• Station and elevation of each point.

• Reach lengths. Channel reach length is measured along the thalweg, overbank reach length is measured along the anticipated path of the center of mass of the overbank flow. Reach lengths specify the distance between the current cross-section and the next cross-section downstream.

• Manning’s n values. For channel roughness, follow the recommendations in the Stormwater Management Manual for the Puget Sound Basin (The Technical Manual) (Washington State Department of Ecology, February 1992), the Surface Water Design Manual (King County Department of Natural Resources, September 1998), or Roughness Characteristics of Natural Channels (U.S. Geological Survey, Water Supply Paper 1849, 1967). The last reference typically focuses on larger creek or river systems than those addressed in this study; appropriate judgment must be applied.

• Main channel bank stations.

• Contraction/expansion coefficients. Typical (default values) are 0.1 and 0.3, respectively. Unusual conditions may warrant modification of these coefficients.

Designating Ineffective Flow Areas, Berms, and Obstructions Ineffective flow areas are areas where flow is nearly stationary and is not actively being conveyed downstream. These can be designated in the “Ineffective Flow Areas” editor.



The most common ineffective flow areas are at cross-sections immediately upstream and downstream of bridges or culverts, on either side of the bridge or culvert opening. Ineffective flow areas should also be designated on cross-sections where off-channel depressions or ponds hold water but without conveying flow downstream. Significant obstructions such as buildings and debris piles within the floodway should be designated using the “Blocked Obstruction” editor. This allows the user to block out single or multiple obstructions in a cross-section. Berms should be indicated using the “XS Levee Data” editor.

Defining Interpolated Cross-Sections It is sometimes necessary to interpolate between two sections where the change in velocity head is too large to accurately determine the energy gradient (e.g., rapidly changing topography such as steep slopes). The change in energy gradient is needed to accurately model friction losses and contraction and expansion losses. The accuracy of the calculations for these interpolated cross-sections will depend on how well the cross-sections match actual field topography. Cross-section interpolations can be made by hand by copying one cross-section and adjusting the elevations and other parameters to fit, using commands under the Options menu, or by using the Cross-section Interpolation command in the Tools menu (see Figure 3).

Figure 3. Methods for Cross-section Interpolation The following rules of thumb should be followed when interpolating cross-sections:

• To minimize error, use interpolation only where channel shape and overbank configuration between two cross-sections is relatively uniform.

• Field surveyed cross-section data should always be used where accurate water surface profile information is required at a particular location. Where this is not possible, interpolate between the two nearest cross-sections and verify with a topographic map and field information.



• Use a topographic map to evaluate the accuracy of interpolated cross-sections. Where the topographic mapping is vague or unclear, a field visit may be necessary to verify actual conditions.

• Interpolated cross-sections should be annotated as such in the cross-section description.

Vertically Extending Cross-Sections Vertical extensions to cross-sections occur automatically when the calculated water surface elevation is higher than the ground surface elevation at the outermost points of the overbanks. Vertical extensions underestimate floodplain storage if the floodplain is wider than the cross-section. Where possible, vertical extensions should be avoided, particularly if additional data can be added from topographic mapping or from a field visit to the floodplain.

Modeling Bridges and Culverts Ideally, four cross-sections are required to model bridge and culvert hydraulics. The survey criteria being used for this project specifies three cross-sections at culverts: one at the upstream face, one along the road centerline to define the overflow elevation, and one at the downstream face. The preferred four cross-sections can be created from the cross-sections measured for this project as follows:

• Use the cross-section at the upstream face and offset a copy of this cross-section upstream to the beginning or end of the contraction of flow into or out of the structure.

• Offset a copy of the downstream culvert cross-section to the point where the flow is fully expanded.

• Field visits should be conducted to verify that the model does not neglect significant channel changes and associated losses.

• The cross-section defining the roadway deck is used solely to establish the overtopping elevation and overflow path.

• When the cross-sections are entered, ineffective flow areas should be marked off on the cross-sections immediately upstream and downstream of the structure. The locations of the ineffective flow areas should extend outward from the edges of the structure opening. Where cross-sections have been added within the zones of contraction or expansion, ineffective flow areas should be located at the edge of the stagnation zone.

Computation Methods for Bridges HEC-RAS offers the following computation options for flow through bridges:

• The standard energy equation (for low flows and high flows)

• The momentum equation (for low flows only)

• Yarnell’s empirical equation (for subcritical low flows only)

• The Federal Highway Administration (FHWA) WSPRO method (for subcritical low flows only)

• Weir flow equations (for high flows only)



• Pressure flow equations (for high flows only).

Low flows, those that remain completely below the superstructure of the bridge, are classified as follows:

• Class A Low Flow—Flow through bridge/culvert is completely subcritical.

• Class B Low Flow—Flow varies from subcritical to supercritical as flow passes through critical depth in the constriction. Where it is likely that Class B flow will not occur, the user should model the stream using a mixed flow regime.

• Class C Low Flow—Flow through structure is completely supercritical.

The computation method is specified by the user (see Figure 4). For low flow conditions, the user can select all available low-flow methods and set the program to use the results of the method that returns the highest energy loss through the structure. For high flows, the user has the option of using either the standard energy equation or the pressure and weir flow equations. As shown in Table 1, the standard energy equation is the most versatile method.

Figure 4. Bridge Modeling Approach Editor



TABLE 1. COMPUTATION METHODS FOR BRIDGES

Energya Momentum Yarnellb WSPROb Weir Flow Pressure

Flow

Low Flow Conditions

Flow Regime

Class A Flow √ √ √ √

Class B Flowc √ √

Class C Flowc √ √

Major Component of Energy Loss

Internal Piers √ √

Friction v √ √

Bothd √ √ √ √

High Flow Conditions Flow against superstructure √ √ √ Bridge overtopped √ √ √

Bridge 95% submergede √

a The energy equation is the best equation to use for modeling long culverts under low flow conditions. If culvert flows full or is controlled by inlet conditions, culvert routines are used.

b Applicable to subcritical flow regimes only. c The momentum equation may be better suited for modeling supercritical flows at locations where pier impact and drag losses

are substantial. d In cases where pier loss and friction loss are both predominant, the momentum method is the most applicable, but other

methods can be used. e Percentage can be specified by user. 95 percent is the program default, meaning when the bridge becomes 95% submerged,

the program switches from using the broad-crested weir flow equation to using the energy equation.

Source: U.S. Army Corps of Engineers, Hydrologic Engineering Center. July 1995. HEC-RAS River Analysis System.

Culvert Routines As a general rule of thumb for culverts, a Manning’s n value of 0.013 should be used for smooth-wall pipes and a value of 0.024 should be used for corrugated pipes. Deviations from this rule of thumb may be necessary in specific cases, but these should be documented. In addition, FHWA entrance and exit loss coefficient tables for culverts should be used when specifying these coefficients (entrance losses are also listed in Tables 6.3 and 6.4 of the HEC-RAS Hydraulic Reference Manual).

Miscellaneous Scenarios Skew Angles. Where the structure is on a skew with respect to the direction of flow through the opening, the user can specify the skew angle and the program will create an equivalent cross-section. The user can specify angles for both deck-and-roadway skew and pier skew in the Bridge/Culvert Skew menu under Options. Skew angle should be based on the angle of the thalweg for the flow being modeled. The publication Hydraulics of Bridge Waterways (Bradley, 1978) discusses the results of hydraulic testing showing that for skew angles up to 20 degrees, flow efficiency was not



significantly decreased. Skew angles greater than 20 degrees have detrimental impacts on flow efficiency. Multiple Bridge or Culvert Openings. Two methods can be used in HEC-RAS to model multiple bridge, culvert, and open channel combinations: the multiple opening computational method or the divided flow method. The multiple opening method is suitable for most situations. In it, the user defines the characteristics of each opening and structure. When using this option, it is usually best to allow the program to choose the flow stagnation points. This saves time and allows these points to shift if multiple flows are modeled. The program models the flows through each structure separately and uses an iterative process to determine the flow distribution between the structures. A principal drawback of this method is that the energy grade lines (EGLs) upstream and downstream of the crossing are assumed to be the same, and the program will only calculate a subcritical profile through the structures. If the slope of the EGL is large and energy losses through the crossing are substantial, the divided flow approach may need to be used instead. The divided flow method takes more time to set up and the user must specify the flow distribution at the upstream junction and identify the stagnation points using the Ineffective Flow Area option. However, if the Flow Split Optimization option is turned on, the program will find the best flow distribution solution using iteration. The divided flow approach allows the user to calculate different water surface elevations and different energy losses through each divided flow reach. Low Water Structures. When low water structures such as footbridges and low culverts are overtopped during design storm floods such as the 25- and 100-year event, they usually become completely submerged and can be modeled using the energy equation. Sometimes, when only high flows are being modeled, these structures may be left out of the model completely. This decision should be based on the range of flows being modeled and the degree to which the structure could obstruct flows and impact water surface elevations. Bed Material in Culverts. Partially aggraded culverts, such as those designed for fish passage, will be accounted for in the Culvert Data Editor by specifying the depth of the culvert that is filled and the “n” value to be used for the culvert bottom. Culverts that do not have fish passage and whose aggradation is the result of the need for maintenance will be analyzed as if clean if the location is identified in the DNR as requiring maintenance.

Steady Flow Files The HEC-RAS models for this project will typically simulate steady flow conditions.

Boundary Conditions Professional judgment should be used in selecting an appropriate boundary condition. Where water surface elevations cannot be obtained from anecdotal information or field observation, the critical depth or normal depth (preferred if subcritical) option shall be used. When using the normal depth option, the energy slope can be approximated by using the average channel slope or the average hydraulic gradient.



Naming Conventions for Profiles and Flow Change Locations Profiles should be named according to the predicted recurrence interval (i.e., 2-year, 10-year, 25-year, 100-year). If the recurrence interval of a flow is not known, an identifier that indicates the flow’s significance should be used if possible, such as “bank full,” or “base flow.” For any FTABLE runs in which the flows are more arbitrary, profile names are not necessary.

Plan Files

Modeling Approach HEC-RAS has two options for calculating overbank conveyance. The default “at breaks in ‘n’ values only” calculates conveyance based on the sum of the wetted perimeter and area between breaks in “n” value. The other choice ‘between every coordinate point (HEC2 style)’, calculates the conveyance for every segment between points on the overbank and then sums the conveyance of all the segments. This is typically used where the results are being referenced to a previous HEC-2 investigation; the default method “at breaks in ‘n’ values only” should be used during this project. There are four options for calculating the friction slope. The default (average conveyance) will be used for this project. There are three options for calculating critical depth. The parabolic method is used during processing to quickly determine the critical depth for each cross-section. The user can also define multiple critical depth search. This option can search for as many as three critical depth values, and will use the lowest energy answer if more than one is found. Most of the time, this level of analysis is unnecessary and the default can be used. However, it may be used where the user feels the program is finding an incorrect answer using the default method.

Flow Regime Selection Selection of the appropriate flow regime, whether subcritical, supercritical, or mixed, will depend on the magnitude of the flow being modeled. The flow regime during low flows can be mixed, becoming supercritical where grades are steeper and subcritical for gentle gradients. The flow regime may change at culverts and bridge crossings, even during higher flows, where critical depth is reached due to the constriction. A mixed flow regime should be used when modeling several flows simultaneously, unless the user has sufficient knowledge of the stream system and modeling experience to correctly predict that the profile will be completely subcritical or supercritical. Processing time using HEC-RAS is very fast compared to other programs such as SWMM, and mixed flow regimes literally take no more time to run than the supercritical and subcritical regimes. As a rule of thumb: if unsure, used ‘mixed.’

USING HEC-RAS TO CREATE FTABLES In some cases, the HEC-RAS models will be used to generate FTABLEs (stage-storage-discharge-surface area relationships) for HSPF models. In such cases, the HEC-RAS modeler should work with the HSPF modeler to determine the limits of each reach in which an FTABLE will be defined and to identify potential flow change locations. Special



consideration needs to be given to stream reaches near junctions. HEC-RAS does not calculate a volume for the reach segment between the junction and the first upstream cross-section in the tributary, and therefore this volume will not be included in the cumulative volume computations calculated for the reach. The volume between the junction and the next cross section downstream (upstream-most cross section of the downstream reach) is also not computed. Thus, the user needs to manually add these volumes to FTABLEs if they are important. Since the FTABLEs will need to be created before the HSPF model can be run, some initial assumptions will need to be made regarding the distribution of concurrent flows throughout a system. Whenever possible, it will help to review the results of previous HSPF models and other hydrologic data in order to help guide these initial assumptions. At this point, a series of increasing flow profiles will be simulated by the HEC-RAS model. While the scope of work states that a minimum of five flow profiles will be used to create the FTABLEs, 10 to 15 profiles should typically be simulated in order to provide a well-defined FTABLE. In selecting the flows that will be simulated by HEC-RAS for creating FTABLEs, it is important to make sure that the highest flow rate is sufficiently high that it will not be exceeded during the HSPF simulations. Otherwise, the HSPF model will have to extrapolate new values for the FTABLE, which can significantly reduce its accuracy. Whenever possible, the modeler should try to track down the 100-year peak flow that was determined by previous analyses for a given reach and make sure that the HEC-RAS flows exceed that 100-year peak flow. It is also important to include a range of low flows (i.e., significantly less than 1-year return interval) to provide adequate definition at the lower end of the FTABLE. The actual formulation of the FTABLE consists of several steps. First, the segment of channel where the FTABLE is required and the corresponding cross-sections is identified. Select the downstream reach to establish the stage and discharge relationship. Then for each of the flows in the FTABLE, calculate the volume occupied by the flow (the sum of the flow area times length for each channel segment). Finally, calculate the surface area by summing the product of the top width and the channel length for each of the channel segments that compose the reach represented by the FTABLE. Once the FTABLEs are created, it will be important for the hydraulic modelers to perform basic quality assurance checks prior to sending out the FTABLEs in order to ensure that the values in each FTABLE are acceptable for HSPF. In general, values in successive rows of an FTABLE must be increasing in order for HSPF to function properly (the only exception is the surface area values, which can remain constant with increasing depths), which does not always occur from the HEC-RAS results. Development of FTABLEs needs to be clearly documented so that they can be updated in the future if needed. For example, documenting the assumptions used to create the flow profiles is important, as well as identifying the specific HEC-RAS reaches and cross sections that were used to generate the FTABLEs for each HSPF reach. Comments should be included in the FTABLEs to indicate the source of information and reference to a specific HEC-RAS model (model, plan, geometry, river, reach, cross sections, station correction, etc.). FTABLEs including the required information should be provided in a text file similar to Figure 5. Individual FTABLEs should be formatted correctly for



direct incorporation into HSPF (i.e. 4 columns of 10 characters each). The FTABLEs cannot contain any tabs to assist in column alignment, otherwise HSPF may not run correctly.

FTABLE 10 *** Developed using HEC-RAS model *** Model: Quilceda Creek *** Plan: Plan 02 *** Geometry: Quilceda.g06 *** River: Quilceda Creek *** Reach: QC *** Stations:1 through 6751 *** STCOR=-3.1 ROWS COLS *** 15 4 DEPTH AREA VOLUME OUTFLOW*** (FT) (ACRES) ACRE-FT) (FT3/S)*** 0.00 0.0000 0.0000 0.0000 0.70 2.3966 0.7220 2.7300 1.09 3.9879 1.9010 8.7000 1.43 5.5167 3.5480 18.3900 1.92 6.1843 6.5480 43.4800 2.39 6.4766 10.1910 86.9700 2.42 6.4960 10.4420 90.3500 2.93 7.1888 15.7930 173.9000 3.81 10.6325 26.9740 394.2000 4.16 17.6975 33.8740 505.8000 4.37 19.4637 38.3820 575.9000 4.60 21.4682 43.6530 656.9000 4.76 22.4779 47.3240 714.4000 4.89 25.1932 51.1410 770.7000 5.17 28.8604 59.3490 891.0000 END FTABLE 10

Figure 5. Typical FTABLE Format Northwest Hydraulic Consultants (NHC) has developed a FORTRAN program to post-process HEC-RAS output data into the FTABLE format. NHC is willing to make this program available to other consultants on the DNR project. Distribution would include the following conditions:

• The program would be provided solely for use on the DNR project, and recipients must agree to discontinue use of the program after the completion of the DNR project.

• The program would be provided as-is and it would be the responsibility of each user to ensure the accuracy of the generated output.

• Documentation for the program is limited and NHC has no budget under the DNR project for support or modification of the program. Modification of or assistance with application of the program would be at the expense of the user.

The procedure for FTABLE manipulation in HEC-RAS depends upon the conditions being analyzed. Under existing conditions, there will be no iterations to the FTABLES for distribution. When evaluating capital projects, a FTABLE will be created representing the hydraulic characteristics of the improvement and iterations performed as required to



encompass the flows associated with the improvement. It is recommended that several improvements be grouped into the same HSPF run to minimize the number of iterations.

HEC-RAS Results Documentation Modeling results will be presented in the DNR using tables and figures according to the report format manual being prepared separately. The HEC-RAS results to be electronically submitted to the County, in addition to the “project files,” are described below. The purpose of these files is to provide a quick reference and summary of the file contents to assist future users in accessing, checking and using model files:

• A report file containing the following input data:

− Plan, flow, and geometric data − Summaries of Manning’s n values, reach lengths, and contraction and expansion

coefficients.

• A profile output table containing key output information (cross-section identifier, flow, water surface elevation, channel velocity, top width, minimum elevation in the cross-section, total cross-section area, volume, weighted ‘n’ value). The tabulated flow will include the four analysis conditions (2-, 10-, 25-, and 100-year).

• A “readme.txt” file containing a description of the project file and each geometry, profile, and plan file. The description should include the filename and extension, title or short identification, and a description of the file, including the conditions analyzed.


EPA-SWMM Model The EPA-SWMM EXTRAN model, version 4.4h, will be used to model developed portions of the watershed. EXTRAN will typically be used to perform unsteady-state analyses, though in some cases, steady-state analyses may be performed. The runoff hydrographs will be developed and produced under the hydrologic portion of the basin analysis using the HSPF model. The HSPF hydrographs and/or peak flows will represent subbasin runoff for existing and future land use conditions prior to installation of any proposed conveyance improvements in the area analyzed; the FTABLE from the HSPF analysis will not be modified to represent conveyance modifications. Proposed conveyance modifications will be analyzed in the SWMM model. For the existing conveyance system, hydrographs for the 2-, 10-, and 25-year events will be developed for both existing and future land use conditions. Improvements to alleviate flooding problems will be designed using the future, 25-year recurrence event. Improvements to address fish passage problems will be designed using the future, 2-year recurrence event. Simulation duration needs to be sufficiently long to capture the effect of any storage facilities. The areas of each DNR basin that will be modeled using the SWMM program were defined in a series of basin meetings as well as in the scopes of work for the project. These are discrete areas within the watershed that typically contain developed, highly piped drainage systems associated with residential or commercial development. The EPA version of SWMM is used because it provides analysis consistency across all teams and ready access to the public domain software at no cost to the County, and because of County staff’s familiarity with EPA-SWMM. Those who require the current EPA-SWMM version may download the software from the following site: http://www.ccee.orst.edu/SWMM.

Data Requirements SWMM hydraulic modeling requires detailed information about the drainage system to be analyzed. Basic information includes pipe invert elevation, diameter, type and length, ground elevation, spatial connectivity information, and outfall tailwater elevation. Surveying efforts by the County and team members will document the physical conveyance network. The tailwater elevation is established from the HEC-RAS analysis for the corresponding event. To be conservative, it is to be assumed that the peak tailwater elevation corresponds to the time period when the SWMM runoff enters the receiving system. Further analysis may be undertaken, if budget permits, to establish the tailwater coincident with the peak discharge from the SWMM basin. For cases in which the SWMM basin discharges into a conveyance network that is not analyzed by the HEC-RAS model, the tailwater elevation will not be known. In these cases, an elevation should be estimated using professional judgment. Depending on the slope and geometry of the receiving system, the tailwater elevation may be based on a

X011084_3538 EPA-SWMM MODEL 2-1 December 2002


normal depth assumption, free discharge assumption, or tailwater estimated from anecdotal information.

Model Development A model schematic will be constructed depicting the drainage network under study. The schematic will include conduit and node identification of the elements represented in the model. The schematic will be spatially correct such that it may be used as an overlay to the mapping of the actual conveyance system after correcting for scale. Where the schematic scale does not allow for clear depiction of the conveyance system, a detail inset may be used to schematically depict this area. At a minimum, this will be a hand-drawn schematic over a topographic base map. The SWMM model will be constructed to coincide with runoff input locations generated from the HSPF analysis. Since SWMM requires input to occur at nodes, the SWMM network must extend to the boundary of the HSPF subbasins to accept the HSPF runoff hydrograph. The hydrologic protocol describes a process for selecting storm events from the HSPF runs that will be input into the SWMM model. The County must review the selected storms prior to their use in the SWMM model. As a general rule of thumb for pipe roughness, a Manning’s “n” value of 0.013 should be used for smooth-wall pipes and a value of 0.024 should be used for corrugated pipes. Deviations from this rule of thumb may be necessary in some cases, but these should be documented. For channel roughness, follow the recommendations in the Stormwater Management Manual for the Puget Sound Basin (The Technical Manual) (Washington State Department of Ecology, February 1992), the Surface Water Design Manual (King County Department of Natural Resources, September 1998), or Roughness Characteristics of Natural Channels (U.S. Geological Survey, Water Supply Paper 1849, 1967). The last reference typically focuses on larger creek or river systems than those addressed in this study; appropriate judgment must be applied. Annotation within the input data file is required. At the start of the file, a block of text will be inserted that summarizes the input file, including the following:

• Major basin name (e.g., North Creek)

• The subarea name of the basin (e.g., Middle2)

• The location of this SWMM analysis by major cross-streets (e.g., Model for the area around 1st Avenue SE and 171st Place SE.)

• The land-use condition (existing or future)

• The status of the conveyance system (existing or modified to represent a capital improvement project (CIP))

• For CIP analyses, a general description of the CIP (e.g., Option 2, replacement of 12-inch system with 24-inch from 1st Avenue SE to 3rd Avenue SE.)

• Any other comments that may be useful to a future user who is unfamiliar with the model or geographical area (e.g., 5-second time-step required for numerical stability of conduit 37A35).



Major divisions of input data will be segregated with a header identifying the following group of input data, such as “Conduits,” “Nodes,” or “Storage.” Further identification may be added if useful to the developer of the model, such as the input sequence of required data. If a “dummy” conduit or node is required, a comment line will precede the dummy to emphasize that the following element does not physically exist. If the data file represents a CIP analysis, then a comment line will be inserted describing the change before each line where a modification to the existing conveyance system is modeled.

Naming Convention The alphanumeric option in SWMM will be used to identify modeled elements, including conduits, cross-sections and nodes that depict manholes, catchbasins, or inlets. About 10 characters may be used for the name, but because of SWMM’s printing format, only seven characters are readable in the output. Unique names assigned to surveyed elements need to be abbreviated for input to the SWMM model to fit this limitation. Surveyed data incorporated into the SWMM model must be traceable to the survey source in the GIS system for potential future model updates. Sufficient documentation must be provided within the input data file for this to occur.

Node Naming Convention (Catchbasins, Manholes, Inlets) Nodes will be named using the last four digits from the survey identifier. In the case of missing or non-existent identifiers, numbering will start with 5 and increase in increments of 5, first along the main stem, then successively along each tributary, from the downstream end of the system to the upstream end. In cases where the survey identifier is truncated, add a comment line just before or to the right of the node input line that contains the full survey identifier. No alphabetic characters are allowed in the node name for this project. When an existing model is modified, insert a node identifier value between the downstream and upstream value unless actual survey identifiers were used, in which case use the actual survey identifier. Dummy nodes will be identified using this same procedure. However, a comment line must be added to identify the node as a dummy. Care must be taken that there is no duplication in node identifiers.

Conveyance Naming Convention (Pipes, Ditches, Channels) Conveyance elements will be identified using a numeric numbering scheme. Starting at the downstream end of the main stem, start numbering with 10 and increase in increments of 10. Any modeled tributaries to the main stem will be numbered starting with a multiple of 1000 starting at the most downstream tributary and incrementing upstream along the tributary in increments of 10 (for example, the first tributary conveyance segment would be labeled as 1000, the second tributary conveyance segment would be labeled as 2000, etc.). Any model refinement resulting in the addition of conveyance elements to the network will use a value between the downstream and upstream label. Cross-sections are assigned a unique name when they are input to the GIS system. That same name will be used in the SWMM model if the model includes any of the surveyed cross-sections and that cross-section represents a single conveyance reach. The full cross-section identifier will be included in a comment line that appears prior to the cross-section entry (cards C2 through C4). Sources for cross-sections that are not



from the survey performed for this project must be documented within the data file, as well as within the model write-up. These may include cross-sections generated from interpolation, field measurements, or previous surveys not part of the County’s GIS database.

File Naming Convention There may be dozens of input files generated for a watershed, depending on the number of detailed study areas identified in the basin and the number of CIPs evaluated. To keep these files organized, a standard naming convention is required. EPA-SWMM is DOS based and is limited to the 8.3 naming restriction of DOS. The following naming convention, using the codes presented in Tables 2 and 3, has been established:

DNR Area Subarea Flood Event Condition Extension Resulting Filename

XXX Y ZZ AA . BBB XXXYZZAA.BBB Using this naming convention, the file name associated with the input data file for the Martha Creek tributary of the Swamp Creek basin containing the 25-year flood for the CIP option number 2 would be called “swa225I2.dat.” Some subareas may contain multiple SWMM models. To maintain naming consistency when this occurs, the last character in the DNR abbreviation (XXX) may be dropped and in its place, a single digit substituted (1, 2, 3, . . . 9, 0) representing the subarea sub-SWMM model. A “readme.txt” file will accompany the SWMM files when transferred to the County that clearly identifies the file name and the corresponding file content including the modeled area description.

Using SWMM for FTABLE Generation SWMM may be used to create FTABLEs for use in HSPF. When doing so, SWMM will be run in steady-state mode using the range of flows required for the FTABLE. Information from the summary tables will then be extracted for the calculation of the parameters for the FTABLE. If there are locations of flooding when running the SWMM model, appropriate surface flooding storage and/or overland flow paths must be accounted for in the construction of the corresponding FTABLE. To construct FTABLES with SWMM, the following procedure may be used. Run the SWMM model under steady state conditions for the flow rate of interest. The summary output table at the conclusion of the SWMM run, entitled “FINAL MODEL CONDITION” contains three sub-tables of interest, entitled “JUNCTION/DEPTH/ELEVATION,” “CONDUIT/FLOW,” and “CONDUIT/FINAL VOLUME.” Using the downstream conveyance element of the SWMM model corresponding to the downstream limit of the FTABLE under construction, tabulate depth, volume (sum of all SWMM conveyance elements associated with this FTABLE) and flow. Repeat for each flow used in the FTABLE. The area parameter in the FTABLE needs to be calculated externally from SWMM. Using the value of depth from the “JUNCTION/DEPTH/ELEVATION,” calculate the conveyance top width for the upstream and downstream end of the conveyance element. Average the values and multiply by the length of the conveyance element. Perform this procedure for each conveyance element that is included in the associated FTABLE and sum the results. Use the resulting value in the FTABLE for this flow.



Repeat for each flow contained in the FTABLE. This procedure may be sped-up by developing a spreadsheet into which the SWMM table may be imported that then calculates the required parameters. Documentation of this process, including output files, spreadsheets and other required materials will be included in the submission to the County with the other modeling results. The County requires the capability to reproduce the FTABLES used in this analysis and have the capability of revising the values in potential future modeling exercises.

TABLE 2. NAMING CONVENTION CODES FOR DNR AREAS AND SUBAREAS

DNR Area Subarea Full Name Abbreviation (XXX) Full Name Abbreviation (Y) Allen Creek All N/A 1 Darrington Dar N/A 1 Gold Bar Gol N/A 1 Granite Falls Gra N/A 1 Little Bear Creek LBC N/A 1 Marshland North MNo N/A 1 Marshland South MSo N/A 1 Monroe Mon N/A 1 North Creek NCk North 1 Middle 2 2 Middle 1 3 South 4 Penny Creek 5 Silver/Nickel 6 Puget Sound Pug Lunds Gulch North 1 Lunds Gulch South 2 Norma Creek East 3 Norma Creek West 4 Lake Serene 5 Quilceda Creek Qui MF/Upper 1 West Fork 2 Lower 3 Mouth 4 Smokey Point 5 Edgecomb/Olaf Straad Creeks 6 Snohomish Sno N/A 1 Stanwood Sta N/A 1 Sultan Slt N/A 1 Sunnyside Ravines Sun N/A 1 Southwest Sou N/A 1 Swamp Creek Swa North 1 Middle 2 South 3 SW 4 Martha Creek 5 Scriber Creek 6



TABLE 3. NAMING CONVENTION CODES FOR FLOOD EVENTS, CONDITIONS,

AND EXTENSIONS Flood Event Abbreviation (ZZ) Two-year flood event as extracted from HSPF. 2y Ten-year flood event as extracted from HSPF. 10 Twenty-five year flood event as extracted from HSPF. 25 Condition Abbreviation (AA) Existing land use condition, existing conveyance system. Ex Future land use condition, existing conveyance system. Fu Future land use condition, improved conveyance system representing CIP improvement 1, 2 or 3, respectively.

I1, I2, I3

Extension Abbreviation (BBB) ASCII data file containing the SWMM input parameters. Dat The complete ASCII output file created from the execution of SWMM. Out An optional abbreviated output file, typically consisting of tabulated values of peak flow, maximum water surface elevation, flow volume, and continuity check.

Sum


General Considerations

Use of Other Models Numerous other models may be used in support of the hydraulic analysis. The use of these models must be documented in the technical appendix discussing modeling analysis for each DNR. The name and version of the model needs to be included. These models may include commercial, proprietary, personal, or “in-house” programs. These other models are to be “support” models that may generate input for one of the primary analytical models (SWMM or HEC-RAS). The technical appendix discussion of these models needs to include how these models were used in support of the primary models. These “Other Models” may be broken-down into three general categories, including:

1. Small backwater analyses programs 2. Culvert analyses programs 3. Utility programs.

Approved models for small backwater analyses programs include the King County suite of applications including bwpipe, bwchan, and bwculv. Use of these programs is limited to simple linear conveyance systems that do not warrant more complex analysis requiring SWMM or HEC-RAS. Gregg Farris at Snohomish County is required to be informed of the use of these programs beforehand if the system proposed to be analyzed is more complicated than just a few elements or if the system contains branches. The approved culvert analysis programs include HY8 and Culvert Master. HY8 is public domain software available from the Federal Highway Administration (FHWA). Culvert Master is proprietary software that contains the same basic equations as HY8 but has improved graphics and output capability. Approved utility programs include Flow Master and HydroCalc. These are simplistic programs designed to calculate various hydraulic parameters, such as depth or velocity in a drainage element. These programs, along with other unnamed programs, may be used to assist in the creation of some FTABLES.

Model Result Presentation The presentation of modeling results will follow the format established in the Lake Stevens Master Drainage Plan. Existing and future flooding problem areas will be symbolically represented on a GIS figure using an orthophoto as the base. Symbology will be color-coded to represent flood frequency, and symbols will vary to represent the type of flooding (overbank flow, flooding of County roads, or flooding of driveways).

X011084_3538 GENERAL CONSIDERATIONS 3-1 December 2002


X011084_3538 GENERAL CONSIDERATIONS 3-2 December 2002

Quality Assurance/Quality Control Quality control should be performed at numerous levels during the modeling, ranging from model assembly through analysis and the presentation of results. Ultimately, the DNR lead is responsible for producing an accurate numerical representation of the physical system, useful results and clear documentation. Basic checks that should be performed during the modeling are included in Table 4.

TABLE 4. HYDRAULIC MODELING

QA/QC CHECKLIST Model SWMM HEC-Ras# Other

Issue Y N Y N Y N 1 Has the model network been reviewed?

2 Has the model schematic been included with the submittal?

3 Have you reviewed the model output to address any warning and error statements?

4 Is the model numerically stable?

5 Is the continuity error below 5%?

6 Are the boundary conditions correct for the analysis at hand?

7 Are the cross-section shapes (berms, flow obstructions, etc.) being interpreted correctly?

8 Have you confirmed the flow direction of floodwater (ponding, overland flow, and direction of overland flow)?

9 Are hydraulic structures, such as weirs, behaving as expected?

10 Have you reviewed the model results for excessive or unusual velocity or flows?

11 Have you reviewed the model input data for the reasonableness of the roughness coefficients?

12 Do flows typically increase traveling in the downstream direction?

13 Are flow regime transitions represented correctly?

14 Is flow continuity correct at split flow locations?

15 Is flow continuity correct between sections?

16 Is the ineffective flow area correct?

17 Did you run Check-RAS to check for model problems?

18 Have you checked key culvert and bridge locations to ensure hydraulics are represented correctly?

19 Are any overtopping bridges or culverts represented correctly (flow path, hydraulics)?

20 Are expansion/contraction reasonable between sections?

21 Have you applied a "reality check" to calculated flows, depths and velocity?

Shaded area means not applicable.

Volume III Habitat Assessment and

Analysis Protocols

December 2002

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425-388-3464

Introduction The Habitat Assessment and Analysis protocols for the Drainage Needs Reports project consist of the following five elements, which are presented here in Volume III of the DNR Protocols.

VOLUME III.A Physical Habitat Survey and Monitoring Protocol for Wadable Streams

VOLUME III.B Wetland Assessment Methods

VOLUME III.C Riparian Assessment Methods

VOLUME III.D Culvert Assessment Protocol for DNR Streams

VOLUME III.E B-IBI Sampling Protocol for DNR Streams

Introduction INTRODUCTION - HABITAT.DOC 1-1 December 2002

Volume III.A Physical Habitat Survey and Monitoring Protocol

for Wadable Streams Version 6.1 UGA/CIP

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Contents Page

Acronyms and Abbreviations ....................................................................................... iii

1.0 Reaches ...............................................................................................................1-1 1.1 Delineation and Selection..........................................................................1-1 1.2 Unit Reach Length.....................................................................................1-1

2.0 Field Equipment ..................................................................................................2-1

3.0 Field Computers and File Management ............................................................3-1

4.0 General Procedure ..............................................................................................4-1 4.1 Comment Field ..........................................................................................4-1 4.2 Station .......................................................................................................4-1 4.3 Protocol for Dry Channels .........................................................................4-1

5.0 Habitat Parameters .............................................................................................5-1 5.1 Bankfull Width ...........................................................................................5-1 5.2 Stream Bank Instability and Hydro-Modification........................................5-3 5.3 Wood Structure Frequency .......................................................................5-6

5.3.1 Riparian Observations ................................................................5-9 5.4 Riffle Habitat..............................................................................................5-9 5.5 Pool Habitat.............................................................................................5-10 5.6 Percent Surface Fines.............................................................................5-11 5.7 Secondary Channel Habitat ....................................................................5-13

6.0 References...........................................................................................................6-1

Figures 3-1 Example Data Entry for Unit Reach Header Sheet ............................................3-2 5-1 Example Data Entry for Start, Midpoint and End BFW Measurements..............5-2 5-2 Example Data Entry for Stream Bank Instability ................................................5-5 5-3 Example Data Entry for Wood Structure ............................................................5-8 5-4 Example Field Computer Data Entry for Pools and Surface Fines ..................5-12 5-5 Example of Data Entry for Secondary Channel Habitat ...................................5-14

Tables 5-1 Decay Class Criteria...........................................................................................5-7 5-2 Minimum Pool Size Requirements ...................................................................5-10

X011084_3538 Contents i December 2002

Acronyms and Abbreviations

BFW bankfull width CIP capital improvement project DBH diameter at breast height DNR Drainage Needs Report LWD large woody debris PC personal computer QA/QC quality assurance/quality control SWM Surface Water Management UGA Urban Growth Area USFS U.S. Forest Service

X011084_3538 Acronyms and Abbreviations iii December 2002

1.0 Reaches

1.1 Delineation and Selection Stream reaches in selected sub-basins were delineated according to Level I stream classification methods (Rosgen, 1996). Physical habitat surveys will be conducted over a randomly selected 25 percent of the total length of each reach type (A, B, C, D, DA, E, F, or G) within wadable, fish-bearing waters during the low-flow period of the year. A ditch category has also been added to Snohomish County Surface Water Management’s (SWM) modified Rosgen reach classification scheme. The quality assurance/quality control (QA/QC) team will resurvey a subset of surveyed reaches for quality assurance and consistency.

1.2 Unit Reach Length Using Rosgen (1996) as a guide, a standard survey reach length of 30 bankfull channel widths was selected. Bankfull width (BFW) measured at the beginning of each unit reach is used to calculate the unit reach length. Less than a length of 30 channel widths will only be measured if the reach type changes before a length of 30 channel widths is obtained. The minimum acceptable reach length is 20 channel widths. If less than the minimum length is surveyed, the collected data will be lumped with information from the adjacent downstream reach (if it is of the same channel type).

X011084_3538 1.0 Reaches 1-1 December 2002

2.0 Field Equipment The following field equipment will be used during survey and monitoring:

• Field computer

• Measuring tape

• Wire grid

• Flagging Tape

• Stadia rod or wading stick

• Hip chain

• Tallywacker

• Plexiglass viewer

X011084_3538 2.0 Field Equipment 2-1 December 2002

3.0 Field Computers and File Management During the survey, data will be entered into a spreadsheet database contained on a Juniper Systems’ AllegroTM Field PC (personal computer). Detailed operating instructions for both hardware and software are contained in the Allegro Field PC owner’s manual, available to all surveyors. The following section describes the procedures each survey team should follow to ensure all data are stored in a useful and organized format.

• Activate the Field PC by pressing the On/Off button (as long as the batteries remain charged, the field computers will revert to suspended mode when turned “off” or not used for a predetermined amount of time). Once activated, most of the subsequent functions are most easily achieved using the touch screen. If for any reason during the survey the touch screen becomes inoperable, most necessary functions can be accessed using the keypad in much the same way as on a desktop PC.

• At the beginning of each unit reach, open (double tap) the shortcut to Str_Datasheet6.1.pt, the main database file. The file contains six worksheets: one header sheet containing the information about the reach to be surveyed, five sheets for habitat parameter data entry and a compilation sheet that organizes data from each of the previous sheets into a single spreadsheet (for data management purposes only). Before entering any data, use the Save As command in the File menu to save the file as the designated reach identification number. Make sure the file saves to the C drive, as this is the solid-state hard drive that stores data even in the event power is lost. A backup copy of the blank spreadsheet is located in C_MyDocs in case the original is saved over.

• Once the file is saved as the reach identification number, check to make sure the caps lock is engaged and begin filling all known reach information into the spaces provided in the header sheet (Figure 3-1). Begin surveying the stream, switching back and forth between habitat parameter sheets by tapping on the tab at the bottom of the screen and filling in appropriate information. Save the file periodically to ensure a minimal loss of data in the event of a computer lockup. At no time should data be entered into the compilation sheet (while the sheet is protected, some data entries are still possible). If data is entered inadvertently into the compilation spreadsheet, use the Undo function under the Edit pull down menu to remove entries (deleting the entry may also delete equations built into the sheet). At the end of the reach, fill in all remaining blanks in the header sheet and perform a final save before closing the file.

• Completed reach files should be transferred to an office PC after each day of survey and checked for invalid or missing data. Any anomalies should be recorded and communicated to the data manager.

X011084_3538 3.0 Field Computers and File Management 3-1 December 2002

Physical Habitat Survey and Monitoring Protocol for Wadable Streams

•

Figure 3-1

Example Data Entry for Unit Reach Header Sheet


4.0 General Procedure

4.1 Comment Field Invariably there will be times when this protocol does not fully capture a situation encountered during a survey. Comment fields are included as part of each spreadsheet in the database and are intended as a means to document instances when a measurement or classification of a habitat parameter is not completely clear. When these situations occur, surveyors are encouraged to make calls based on their best professional judgment. A brief explanation of the decision should be recorded in the comment field associated with the parameter in question.

4.2 Station At the start of each reach, tie off and zero the hip chain. Record a station for each piece of information gathered in the reach. The station designation provides an organizational record for data entry into an extensive field computer database. Where survey measurements are made in the main channel, enter MC in the channel type field within the database. If survey measurements are made in secondary channel habitat, enter SC1 or SC2 (see below). While the hip-chain station reading is fairly arbitrary on a sub-basin scale, it allows the physical habitat information recorded to be analyzed, if need be, on a site-specific level. The station designation also provides the opportunity for quality control surveys.

4.3 Protocol for Dry Channels Fish-bearing (Types 1, 2, and 3) channels that are dry at the time of the survey will be surveyed for BFW and wood and bank instability. If these channels have standing water in pools and these pools meet the survey criteria, they will also be recorded.

X011084_3538 4.0 General Procedure 4-1 December 2002

5.0 Habitat Parameters

5.1 Bankfull Width Purpose: BFW is the primary measure of channel size and is used to determine the minimum size of functioning pools and woody debris along the reach (explained below), as well as the unit reach length.

Definition: BFW is the width of a stream channel at the point where over-bank flow begins during a flood event. In entrenched channels with disconnected or undeveloped floodplains, bankfull indicators may include: the top of deposited bedload (gravel bars), stain lines, the lower limit of perennial vegetation, moss or lichen, or a change in slope or particle size on the stream bank and undercut banks (USFS, 1999). Procedure: Measure BFW at the crest of the first riffle, at the crest of the riffle nearest the midpoint (15 channel widths), and at the crest of the last riffle within the reach (generally 30 channel widths). Straight, low-gradient riffles with uniform banks are best for identifying bankfull stage and therefore, BFW. Locate bankfull stage by using any of the above indicators on at least one of the stream banks. Measure the width of the channel at the indicated point and record it in the handheld computer database (Figure 5-1).

X011084_3538 5.0 Habitat Parameters 5-1 December 2002


Figure 5-1 Example Data Entry for Start, Midpoint, and End BFW Measurements



5.2 Stream Bank Instability and Hydro-Modification Purpose: To assess channel stability and response to watershed conditions. This protocol will follow the definitions used by Bauer and Burton (1993):

Bank Instability: Banks are considered stable unless they show indications of any of the following features at or above bankfull:

• Breakdown: obvious blocks of bank broken away and lying adjacent to the bank breakage.

• Slumping or False Bank: bank has obviously slipped down, cracks may or may not be obvious, but the slump feature is obvious.

• Fracture: a crack is visibly obvious on the bank indicating that the block of bank is about to slump or move into the stream.

• Vertical and Eroding: The bank is mostly uncovered as defined below and the bank angle is steeper than 80o from the horizontal.

Perennial vegetation ground cover is < 50%. Roots of vegetation cover < 50% of the bank. Rocks of cobble size or larger protect < 50% of the bank surfaces. Logs of ≥ 10 cm diameter protect < 50% of the bank surfaces.

Bank Hydro-Modification: For hydro-modified banks, record the type of modification and the material composition of the toe of the feature (at and below the bankfull elevation). For this study we are only considering five categories of hydro-modification:

• DI – Dike/Levee/Berm

• RE – Revetment

• BU – Bulkhead

• BR – Bridge Footing

To capture the extent of beaver dams in the system, we have included an additional category:

• BE – Beaver Dam: distinct beaver created dam, connected bank to bank and impounding water; abandoned dams are not counted.

For this study we are considering only five categories of material composition:

• RI – Riprap: bank material > 256 mm (10 in.) in diameter.

• RU – Rubble: bank material < 256 mm (10 in.) will be considered Rubble (Beamer & Henderson, 1998).

• ST – Structural: other material such as wood (other than large woody debris [LWD]), concrete, and gabion are lumped into this class.

• EA – Earth: includes artificially placed soil as well as other “natural” toe materials.

• BE – Beaver Dam: material that was placed by beavers (used only for beaver dam hydro-modification).



Procedure: Stream bank instability and hydro-modification will be continuously measured along both banks. When a portion of bank that meets the above criteria is encountered, identify whether it is on the right or left bank (facing downstream) and record the hip-chain reading in the field computer database. Continue with the survey collecting data on any and all other required stream features. When the end point of the bank feature is reached, record the hip-chain reading in the database. The length of the feature will be calculated automatically. In instances when the feature is small and more easily measured with a stadia rod or tape, do so and enter the length in the end point column. If the channel is braided, then measure bank feature along the banks furthest to the right and left only. For beaver dams that extend from bank to bank, write a “B” in the bank column, “Beaver Dam” in the hydro-modification column, measure the downstream height and width of the dam, place those measurements in the comments field, and finally measure the length of the hydrologic impoundment (Figure 5-2).



Figure 5-2

Example Data Entry for Stream Bank Instability



Data entry for stream bank instability and hydro-modification:

Required Values: Station (hip-chain reading), start point, end point, and type (erosional or hydro-modified). For hydro-modified banks, also record the material composition. For beaver dams that extend from bank to bank, write a “B” in the bank column, “Beaver Dam” in the hydro-modification column, measure the downstream height and width of the dam, place those measurements in the comments field, and finally measure the length of the hydrologic impoundment.

Automatically Calculated Values: Bank length.

5.3 Wood Structure Frequency (Adapted from Snohomish County Version 6.0)

Purpose: To measure the type and amount of wood providing habitat complexity and hydraulic roughness. Definitions: Wood structures are classified into three categories—woody debris, stumps, and jams—based on the following definitions:

• Woody Debris: defined as downed wood that intercepts bankfull flow in a substantial fashion and is large enough to influence the formation of habitats (USFS, 1999). To be counted as woody debris, a piece of wood must be of a length greater than 7.6 m or greater than twice the BFW of the stream reach being surveyed, whichever is less. Additionally, the diameter of the wood must be greater than or equal to 30 cm at 7.6 m or twice BFW, whichever is less, from the larger end. Wood that spans the bankfull channel and touches just above bankfull on both sides is counted.

• Stump: Rootwad with a diameter greater than or equal to 1 m and a length and/or bole diameter less than the minimum LWD criteria. The rootwad or attached bole must significantly intercept bankfull flow.

• Small Wood: If wood is ≥ 2 m long and ≥10 cm wide at the narrowest end, then the wood is tallied with a hand counter and recorded on the header page at the end of the reach.

In addition to LWD dimensions, wood debris is further characterized by collecting data on rootwad presence, wood type, decay class, and association with a jam. These attributes are defined as:

• Rootwad Presence: for a rootwad to be counted on a piece of woody debris, the rootwad diameter must be at least 1 m.

• Wood Type: deciduous (D), evergreen/coniferous (C), or unknown (U).

• Decay Class: characterizes each piece based on the condition of the wood from natural decay.



Table 5-1 Decay Class Criteria

Decay Classa Bark Twigs Texture Shape Wood Color

1 Intact Varies Intact Round Original Color 3 Trace Absent Smooth Round Darkening 5 Absent Absent Abrasion Round/Oval Dark

a 1 = recent, 3 = intermediate, 5 = old.

Source: Collins et al., 2001 and Schuett-Hames et al., 1994

• Stump: Rootwad with a diameter greater than or equal to 1 m and a length and/or bole diameter less than the minimum LWD criteria. The rootwad or attached bole must significantly intercept bankfull flow.

• Jam: Three or more touching pieces of woody debris and/or stumps (defined above) together producing a single structure significantly intercepting bankfull flow.

Procedure: Measure the diameter of the wood at 7.6 m or twice BFW, whichever is less, from the larger end and record. Measure wood debris length and record as one of two classes:

• Length Class 1 - 7.6 m to BFW • Length Class 2 - Greater than or equal to BFW

Also, determine the wood type, decay class, rootwad presence or absence, and jam association (jam or single piece). Tally and record all stumps which meet the minimum size criteria as defined above. Decay class and wood type information is not required for stumps. Record a general station of all wood debris (including stumps) using the hip chain (Figure 5-3).

Data Entry for wood debris and stumps:

Required Values: Station (hip-chain reading), channel type, diameter, length class, wood type, decay class, and rootwad presence of wood, number of stumps, and whether or not each piece is part of a jam.

Automatically Calculated Values: None.

Comments for wood structure may include, but are not limited to, general descriptions about stream conditions caused by wood or lack of it and potential for future wood recruitment.



Figure 5-3

Example Data Entry for Wood Structure



5.3.1 Riparian Observations Purpose: To assist the riparian assessment team with ground-truthing of hard-to-reach areas and to perform QA/QC, the in-stream team will check the riparian area against the codes the riparian assessment team has marked on the field maps.

Procedure: Determine dominant vegetation conditions within major riparian units. Riparian conditions will be marked on field maps by the riparian assessment team. The riparian assessment team assessed the area in approximately 500-ft units. The assessment is intended to be low resolution, and the in-stream crews will check the accuracy of this low-resolution assessment. If this assessment is reasonably accurate, then the field map will receive a check; if the assessment is inaccurate, the field team will correct the field map with the following codes. Riparian observations proceed as follows:

A. Note major changes in riparian condition on the left and right bank. A major change is change in dominant vegetation cover that is at least 500 feet long. Mark station and bank on data sheet.

B. Classify riparian conditions using the criteria in Riparian Assessment Methods (Vegetation Type, Tree Size Class, Stand Density, and Stand Width). Each riparian unit shall always have four letters assigned. For example, Riparian Unit L1 may be classified as "CLDW", corresponding to Conifer, Large, Dense, Wide.

Data Entry for riparian:

No data entry on datasheets is required. Check the hard copy of the field maps for the relative accuracy of the riparian assessment. If this assessment is reasonably accurate, then the field map will receive a check; if the assessment is inaccurate, the field team will correct the field map with the above codes. If the field maps have not been assessed, check with the riparian assessment leads.

5.4 Riffle Habitat Procedure: To obtain Pool:Riffle ratios of the assessment reaches, the habitat team will collect hip-chain data on the beginning and ending of the riffle. The data analysis will later calculate length and its ratio to total pool length. A riffle is defined by the American Fisheries Society as:

“…characterized by small hydrologic jumps of rough bed material, causing small riffles, waves, and eddies…” (Armantrout,1998).

To obtain this measurement, the habitat team will enter the following data in the Pools_Fines tab of the computer (Figure 5-4):

1. Enter the hip-chain location in the first column.

2. Enter a “Y” in the “Riffle (Y/N)” column.

3. If a “Y” is entered, the “Riffle Start” hip-chain measurement will automatically load.

4. Finally, in the “Riffle End” column, enter the hip-chain location of the end of the riffle.



5.5 Pool Habitat Purpose: To measure habitat area available for holding and rearing.

Definition: Pool – a section of stream channel where water is impounded within a closed topographical depression (Abbe and Montgomery, 1996). For a habitat unit to qualify as a pool in this survey, it must meet the minimum area and depth requirements in Table 5-2.

Procedure: Pool parameters will be recorded for pools meeting the BFW, residual depth and surface area criteria described in Johnston and Slaney (1996). See Table 5-2.

Table 5-2 Minimum Pool Size Requirements

Bankfull Width (m) Area (m2) Residual Pool Depth (m)

0 – 2.4 0.5 (5.4 ft2) 0.20 (0.7 ft) 2.5 – 4.9 1.0 (10.8 ft2) 0.40 (1.3 ft) 5.0 – 9.9 2.0 (21.5 ft2) 0.50 (1.6 ft)

10.0 – 14.9 3.0 (32.3 ft2) 0.60 (2.0 ft) 15.0 – 19.9 4.0 (43 ft2) 0.70 (2.3 ft)

>20 5.0 (53.8 ft2) 0.80 (2.6 ft)

Source: Johnston and Slaney, 1996.

When a pool is encountered, do the following:

A. Measure the maximum pool depth and tailout depth using a stadia or wading rod.

B. Calculate the residual pool depth (maximum depth minus pool tailout) manually with a calculator or automatically by entering the depth values into the appropriate database fields.

C. Maximum pool depths of more than 2 m (6.6 ft) may be entered into the spreadsheet as 2.0 with “over 2 m” entered in the comment field.

D. If the calculated residual depth value falls within the criteria in Table 5-2, measure the mean wetted width and length of the pool, and the mean functional width and length. The functional area is the area of the pool most likely to be used by adult salmonids for holding, and is defined by a depth of ≥ 0.20 m (0.7 ft) or the pool tailout depth, whichever is greater. This definition captures the deeper areas of the pool and excludes the shallow margins as the pool tapers toward the banks.

E. If the functional area meets the area requirements in Table 5-2, the pool is of acceptable size. If it does not, remove the entered measurements from the record and continue surveying.

F. When two or more pools occur in sequence, they should be split and measured separately whenever there is a clear division (tailout) between them.

Calculate the functional pool surface area (length x width) manually with a calculator or automatically by entering the functional pool length and width values into the field



computer database. If the calculated area falls within the criteria for the BFW, enter all of the remaining required information for the pool unit into the field computer database.

Data Entry for pools meeting minimum size criteria:

Required Values: Station (hip-chain reading), channel type, maximum and pool tail depths, wetted and functional pool length, and mean wetted and functional pool width.

Automatically Calculated Values: Pool residual depth and functional pool area.

5.6 Percent Surface Fines Purpose: To measure the percent surface fines in potential spawning locations and thereby the risk to eggs and juveniles from entombment, oxygen depletion, gill abrasion, and foraging difficulty.

Definitions:

Surface fines – fine sediment particles that are < 6.3 mm (0.25 in) (Bauer and Burton, 1993; Rhodes and Purser, 1998.)

Procedure: Measure surface fines at the riffle crest/pool tailout directly downstream of the first four pools that meet the criteria for minimum functional pool area and have a mean diameter bed surface particle size (ocular estimation) less than or equal to 13 cm (5.1 in.) within the riffle crest/pool tailout.

At all sites where fine sediment measurements are taken, establish a cross-sectional transect perpendicular to flow and within 2 m (6.6 ft) upstream or downstream of the riffle crest/pool tailout within the most likely redd position. Record the width of the wetted channel. Divide the transect into five equal sections, excluding the slackwater margin and backwater features. Using a grid method adapted from Bauer and Burton (1993), Lisle (1989), Lisle and Eads (1991), and Rhodes and Purser (1998), measure the percentage of fines at each of the dividing points between the equal segments (four samples per site).

Place the 100 cross-section grid at the first point along the transect described above. Using an Aqua scope or a plexiglass viewer to reduce surface glare, count the number of grid points directly underlain by fine substrate < 6.3 mm (0.25 in.) (Bauer and Burton, 1993; Rhodes and Purser; 1998). If the grid point falls on larger substrate (cobble, boulder, bedrock, etc.) at a point where the substrate is covered with fines, count the point. If the grid point falls on dark interstitial areas between gravels, cobbles, etc., assume there are no fines and do not count.

Repeat this procedure at each established point along the transect. Record the number of points underlain by fines for each grid position along the transect in the handheld computer database (Figure 5-4). Repeat this procedure at each established point along the cross-section.



Figure 5-4

Example Field Computer Data Entry for Pools and Surface Fines



Data Entry for percent surface fines measurement:

Required Values: Station (hip-chain reading of second and third transect if necessary), channel type, and number of grid points underlain by fines for each measured point.

Automatically Calculated Values: Total percent fines for each transect in redd position.

5.7 Secondary Channel Habitat Purpose: To quantify habitat in secondary channels and identify significant off-channel features.

Definition: Secondary channels are defined as channels that are separated from the main channel by a stable island and contain the smaller portion of the total flow. A stable island in a forested stream is defined by USFS (1999) as supporting woody vegetation (excluding willows that do not meet the tree definition), which is estimated to be at least 5 years old (and covers at least 50 percent of the island surface). Off-channel habitats include marshes, ponds, and oxbow lakes that are outside the bankfull channel.

Procedure: Identify whether or not a potential secondary channel feature is separated from the main channel by a stable island. If the feature is not separated by a stable island, then lump it in with the main channel measurements. If the feature is located outside the bankfull channel, then describe the off-channel feature in the comments.

For all secondary channels identified, record the station at the first point encountered where the channel connects to the main channel. Determine whether the secondary channel within the bankfull channel is dry, connected at one end (channel type SC1), or connected at both ends (channel type SC2) at the time of the survey, and record the corresponding code in the database. Tie off and break the hip chain; measurements will continue from this point after secondary channel measurements are completed. Measure (with a stadia rod or tape) the length, mean wetted width, and mean BFW of the secondary channel. Record these values in the field computer database (Figure 5-5).



Figure 5-5

Example of Data Entry for Secondary Channel Habitat



Survey the secondary channel following the same protocol for mainstem channels. Enter any new lines of data at the original side channel hip-chain station (i.e., two pools in the same side channel require two lines in the database). Each line should be recorded with the identical station numbers (the first point encountered where the side channel enters the stream). See Figures 5-1, 5-2, 5-3, and 5-4. When all values for the secondary channels are collected, return to the point where the hip chain was placed and continue the main channel survey.

Significant off channel habitat features that are outside the bankfull flow should be noted in the comments but not measured.

Data Entry for secondary channel measurements:

Required Values: Station (hip-chain reading where side channel enters the main channel), channel type (SC1 or SC2), length and average wetted width of side channel, and the required values for any woody debris, pools, and riparian conditions that meet survey criteria.

Automatically Calculated Values: Wetted area, bankfull channel area.


6.0 References

Armantrout, N. B., compiler. 1998. Glossary of Aquatic Habitat Inventory Terminology. American Fisheries Society, Bethesda, MD.

Abbe, T. B. and D. R. Montgomery. 1996. Large Woody Debris Jams, Channel Hydraulics and Habitat Formation in Large Rivers. Regulated Rivers: Research & Management 12:201-221.

Bauer, S. B. and T. A. Burton. 1993. Monitoring Protocols to Evaluate Water Quality Effects of Grazing Management on Western Rangeland Streams. U.S. Environmental Protection Agency Region 10, Seattle, WA.

Collins, B. D., D. R. Montgomery, and A. D. Haas. 2002. Historic Changes in the Distribution and Functions of Large Woody Debris in Puget Lowland Rivers. Submitted to Canadian Journal of Fisheries and Aquatic Science. 59:66-76.

Johnston, N. T. and P. A. Slaney. 1996. Fish Habitat Assessment Procedures. British Columbia Ministry of Environment, Lands and Parks and British Columbia Ministry of Forests, Watershed Restoration Program, Tech. Circ. No. 8. 97 pp.

Lisle, T. 1989. Sediment Transport and Resulting Deposition in Spawning Gravels Channels, North Coastal California. Water Resources Research 25:1303-1319.

Lisle, T. and R. E. Eads. 1991. Methods to Measure Sedimentation of Spawing Gravels. USDA-FS Pacific Southwest Research Station, Research Note PSW-411.

Rhodes, J. J. and M. D. Purser. 1998. Overwinter Sedimentation of Clean Gravels in Simulated Redds in the Upper Grande Ronde River and Nearby Streams in Northeastern Oregon, USA: Implications for the Survival of Threatened Spring Chinook Salmon. Pages 403-412 in M.K. Brewin and D.M.A. Monita, tech. coords. Forest-Fish Conference: Land Management Practices Affecting Aquatic Ecosystems. Proc. Forest-Fish Conf., May 1-4, 1996, Calgary, Alberta. Natural Resources Canada, Canadian Forest Service, Northern Forestry Centre, Edmonton, Alberta. Inf. Rep. NOR-X-356.

Rosgen, D. L. 1996. Applied River Morphology. Pagosa Springs, CO: Wildland Hydrology Books.

Schuett-Hames, D., A. Pleas, L. Bullchild, S. Hall, eds. 1994. Ambient Monitoring Program Manual. Timber-Fish-Wildlife, TFW-AM9-94-001. Northwest Indian Fisheries Commission, Olympia, WA.

United States Forest Service (USFS). 1999. Stream Inventory Handbook: Level I & II. USDA, Region 6, Version 9.9.

X011084_3538 6.0 References 6-1 December 2002

Attachment Project Reconnaissance Survey

Snohomish County DNR

Project Reconnaissance Survey

��


Contents Page


1.0 Purpose................................................................................................................1-1

2.0 Methods ...............................................................................................................2-1



CIP capital improvement project DNR Drainage Needs Report GIS Geographic Information System NMFS National Marine Fisheries Service WDFW Washington Department of Fish and Wildlife


1.0 Purpose The purpose of the reconnaissance element of the aquatic habitat assessment is to increase the level of coverage of streams more cost-effectively than with the quantitative survey. There will be a tradeoff of quantitative data for subjective assessment (best professional judgement). The assumption is made that several times as much stream length can be assessed per unit of time using this method than with the quantitative method. This will also be used to assess reaches identified to be potentially important based on information obtained during the quantitative surveys or from any other source, including residents, basin stewards, Washington Department of Fish and Wildlife (WDFW) biologists, or other team members. The overall intent is for the field teams to extrapolate the findings of the quantitative assessment into these less sampled areas.

X011084_3538 Acronyms and Abbreviations 1-1 December 2002

2.0 Methods The reconnaissance survey is based on the level 1 survey protocol used by the U.S. Forest Service region 1. It is basically a checklist of limiting factors. The factors have answers of either good/fair/poor or yes/no to assess habitat factor rating or whether or not a factor appears to be limiting. The criteria used for making these judgements are based on the habitat rating table developed in the Tri-County Urban Issues Endangered Species Act study. This table was peer reviewed by a distinguished panel of local experts, including representatives from National Marine Fisheries Service (NMFS), WDFW, and University of Washington. The rating table is based, in part, on the NMFS habitat quality-rating table used to delineate properly functioning habitat.

In addition to the habitat rating elements, the data form records routine information such as reach identification, date, time, personnel, etc. This will later be entered into a Geographic Information System (GIS) layer. Ample space is provided for comments at the bottom of the page. At minimum, this should characterize the essence of the reach examined and potential capital improvement project (CIP) effort, if appropriate.

Photographs are expected to be taken commensurate with the observed importance of the reach. For instance, if a likely CIP is found (e.g., a passage block), more photos should be taken than if habitat observed is typical. These photos are intended to help you in your later write-up of the assessment. Field maps should be marked showing the location and extent of reconnaissance effort.

An important aspect of this protocol is that it requires an extensive use of best professional judgement. The habitat quality-rating table is a reference rather than an actively used assessment tool. Otherwise, hard data would have to be taken and analyzed, defeating the purpose of this effort. As such, this task needs to be carried out by an experienced salmonid habitat biologist.

X011084_3538 2.0 Methods 2-1 December 2002

Attachment Qualitative Analysis Field Form

Snohomish County Drainage Needs Qualitative Assessment Field FormDate: Team Name:Sub Basin: Stream Name:Rosgen Class: Reach ID Number:Site number Lat.: Long:Sample Location: Above Culvert (y/n)?Photo Roll: Photo Numbers:

Limiting Factors Good (1) Fair (2) Poor (3) Yes (Y) No (N)

Subjective Habitat RatingImproving HabitatDeteriorating Habitat

Unstable banksHydro-modificationsLack of ShadeEutrophicationFlashy HydrologyTurbidityLack of Undercut banks

Spawning AreasPool AbundancePool QualityRiffle abundanceAquatic Invertebrate QualityBank Cover (e.g.Brush and Roots)Riparian CoverLarge Woody DebrisEmbeddedness

Dominant/Subdominant Substrate (in mm) Check Box

Silt/Clay/ Organic (<0.059)

Sand (0.06-1)

Small Gravel (.25-1.25)

Large Gravel (1.25 -2.5)

Cobble/ Boulder (>2.5)

DominantSubdominant

Approximate % Grade: Comments:

Habitat Ratings

Habitat Trend:

Are the Following Limiting Factors for Habitat?

Volume III.B Snohomish County

DNR Project Wetland Assessment Methods

��


Contents Page


1.0 Introduction .........................................................................................................1-1

2.0 Office Inventory...................................................................................................2-1 2.1 Items Needed ............................................................................................2-1 2.2 Revision of Wetland Polygons...................................................................2-2 2.3 Identify Wetlands Overlooked by Previous Inventories .............................2-3 2.4 Transfer of Base Maps to GIS Team.........................................................2-4

3.0 Field Verification of Results ...............................................................................3-1

4.0 Transfer of Base Maps to GIS Team..................................................................4-1 4.1 GIS Analysis and Input ..............................................................................4-1

5.0 References...........................................................................................................5-1

Tables Page 2-1 Field Measurements for Stream Assessments...................................................2-2



CIP capital improvement project DNR Drainage Needs Report GIS Geographic Information System NWI National Wetland Inventory QA/QC quality assurance/quality control UGA Urban Growth Area


1.0 Introduction Wetlands within each DNR (Drainage Needs Report) area will be assessed for several attributes that influence the quality of salmonid habitat in fish-bearing streams. The results of this assessment will help determine which wetlands are appropriate for acquisition, enhancement, and/or restoration. Wetland assessment will begin with an office inventory of maps, aerial photographs, and relevant reports. After the office inventory, field teams of consultants and Snohomish County ecologists will do selected ground verification of the office assessment results. Following the field assessment, the Geographic Information System (GIS) team will finalize base maps and analysis of ecosystem attributes will take place. The resulting information will be incorporated into our overall ecosystem analysis and will assist in development of a prioritized Capital Improvement Project (CIP) list.

Wetland assessment will be limited to wetlands that occur only within Snohomish County Urban Growth Area (UGA) boundaries and outside city limits. Wetlands may be assessed outside of the UGAs if there is a high potential for these wetlands to affect conditions within the UGA. The wetlands identified within the small UGAs will be qualitatively assessed outside of this protocol, as described in the original scope of work.

X011084_3538 1.0 Introduction 1-1 December 2002

2.0 Office Inventory The office inventory will obtain two objectives: (1) revise the County wetland inventory polygons, and (2) identify potential wetlands overlooked by previous County or national wetland inventories.

One important note: The assessment team will verify all office assessments with County representatives to ensure consistency between the assessment team and the County in their analysis and interpretation of the wetland areas, size, and Cowardin class.

2.1 Items Needed The office inventory for wetland conditions will be conducted concurrently with the office inventory for riparian conditions. To perform these assessments, the teams will use the following maps, aerial photographs, and related information:

• Original 1995 high-resolution photos (1 inch = 400 feet) and 1991 stereo pairs (~1 inch =2000 feet) will be reviewed at the Public Works records office if available (first floor, Wall Street; 425/388-6453; Dave Evans, Supervisor).

• Supplementary information, such as County soil surveys, relevant basin studies, and sensitive areas reports for individual projects, will be incorporated when available. The Consultant assumes that the County will provide all supplementary information prior to the office assessment of the aerial photograph-based maps.

• 1988 (or later) aerial photograph-based maps overlain with existing inventory information from the County. Base maps will be at a scale of 1 inch = 500 feet, utilizing a black and white photo base and color inventory information. The GIS team will provide the following information on assessment maps:

− DNR basin and sub-basin boundaries

− UGA and City boundaries

− Boundary of study area

− Section, Township, and Range

− Existing wetland inventory information (National Wetland Inventory [NWI] or County wetland inventory [with ID plotted])

− Each County wetland inventory polygon will be given a unique identifier to indicate basin, sub-basin, and wetland number. Wetland numbers will be assigned to each County-mapped wetland polygon in sequence by sub-basin and will be available on the base maps. The basin and sub-basin wetland identification codes are provided in Table 2-1.

X011084_3538 2.0 Office Inventory 2-1 December 2002

Wetland Assessment Methods

Table 2-1 Wetland Identification Codes

Basin Sub-basin Wetland Identification Code

Marshland Drainages Sunnyside MASU North MANO South MASO Quilceda Mouth QUMO Lower QULO Middle QUMI Smokey Point QUSM West Fork QUWF Swamp Creek Middle SWMI North SWNO Martha SWMA Small SW UGA SWSW South SWSO Snohomish SNSN East Valley UGAs (DNR 6) Monroe EVMO Sultan EVSU Gold Bar EVGB Stanwood (DNR 7) STAN Allen Creek (DNR 8) ALLN Little Bear (DNR 9) LILB North Creek (DNR 10) North NCNO Middle 1 NCM1 Middle 2 NCM2 South NCSO Penny NCPE Silver/Nickel NCSN Puget Sound Drainages (DNR 11) PSDR

2.2 Revision of Wetland Polygons The revision of the County wetland inventory will focus three elements: (1) changes in the areal extent of wetlands previously identified as a result to changes in land use, (2) contradictory information from NWI and County inventories, and (3) determining the Cowardin classification of the wetland. Each of these elements will be assessed by aerial photograph interpretation. Changes in wetland boundaries will be marked by hand on the aerial photograph-base maps on mylar/acetate overlays. The assessment teams will examine the following:

• The locations where wetland areal extent has been reduced by land use changes.



• The locations where wetland areal extent may be greater than indicated by the County wetland inventory (i.e., locations where the NWI wetland boundaries encompass a larger area than the County inventory information).

• The County wetland inventory includes numerous wetlands that share boundaries, indicating wetland complexes of multiple wetland types. The Consultant will indicate the boundaries and sub-boundaries of these wetland complexes on the aerial photograph-based maps, and will update the wetland identification codes to indicate these situations.

• Classification of the wetlands will be determined using the Cowardin system as defined in the U.S. Fish and Wildlife Service report Classification of Wetlands and Deepwater Habitats of the United States (Cowardin et al., 1979). For the purposes of this report, the classifications will include the System (Palustrine) and the Class (Forested, Scrub-Shrub, and Emergent) and will use the lettered codes as outlined in the above-mentioned report.

For each existing wetland polygon, the Consultant will record information into a spreadsheet format for future incorporation into the County’s sensitive areas information database. Parameters to be recorded include:

• Wetland identification code (from Table 2-1)

• County wetland identification number (from base maps)

• Wetland (and sub-boundary) size (acres)

• Wetland (and sub-boundary) classification according to Cowardin et al. (1979)

• Was the wetland field checked (Y1 indicates on-site field check, Y2 indicates remote field check; N indicates no field check)

2.3 Identify Wetlands Overlooked by Previous Inventories

In addition to the revision of the County wetland polygons, the office inventory will identify areas of potential wetlands that have not been previously included in the County wetland inventory. These areas will be marked by hand on mylar/acetate overlays of aerial photograph-based maps. The size of these areas will not be estimated from the aerial photos, but will be estimated during the field assessment and GIS analysis. The Cowardin class will be evaluated from the aerial photos and will be verified or corrected by the field team.

For each newly identified potential wetland area, the Consultant will record into the spreadsheet the following parameters:

• Wetland identification code (from Table 2-1)

• New County wetland identification number (to follow sequentially after the last used County number)

• Wetland (and sub-boundary) size (acres)

• Wetland (and sub-boundary) classification according to Cowardin et al., 1979

• Was the wetland field checked (Y1, Y2, or N)



2.4 Transfer of Base Maps to GIS Team Upon completion of the office assessments, all of the base maps will be sent to the GIS team for inclusion in the County’s sensitive area database.


3.0 Field Verification of Results During the office inventory and the County QA/QC, wetlands will be identified for field verification. Field verification will be distributed between Consultant and County field teams. The field effort will be focused on important existing wetland systems such as wetlands at the confluence of two streams, very large wetlands (5 acres or more), and/or wetlands that have undergone a significant change from the base-map conditions. Additionally, the field team will attempt to visit the newly identified potential wetland complexes and confirm the existence of a wetland, verify the office assessment, and provide CIP recommendations, assuming access and time are available.

The field teams will verify the data collected from the office inventory and provide additional notes to aid in the development of CIP recommendations. The field teams will adjust the polygons drawn on the base maps. The GIS teams using the corrected base maps will complete the final size determination. The Cowardin classification will also be verified and amended as necessary. In addition to verifying the office assessments, the field team will provide notes to assist in the analysis of wetland function and the development of CIP recommendations.

Field data will be recorded on the Wetland Assessment field data sheets and results will be used to correct the spreadsheet and/or base maps.

X011084_3538 3.0 Field Verification of Results 3-1 December 2002

4.0 Transfer of Base Maps to GIS Team Upon completion of the field assessments, all of the base maps will be sent to the GIS team for inclusion in the County’s sensitive area database.

4.1 GIS Analysis and Input Upon completion of the office and field effort, the GIS team will determine the size of the wetland polygon and the change in size of the wetland polygon. The GIS team will include this information in their database.

X011084_3538 4.0 Transfer of Base Maps to GIS Team 4-1 December 2002

5.0 References Cowardin et al. 1979. Classification of Wetlands and Deepwater Habitats of the United

States. FWS/OBS-79/31. U.S. Fish and Wildlife Service, Office of Biological Services, Washington, D.C.


Attachment Wetland Field Data Sheet

Snohomish County DNR Project Wetland Field Data Sheet DNR Basin: Date:

Location:

Crew:

County Wetland Code: Basin Specific Code:

Wetland Present: YES NO

Cowardin Class:_________________

Wetland Vegetation—indicate dominant species (≥20% cover) with an asterisk (*).

Tree Species

Shrub Species Herbaceous Species

Photos Taken? YES NO. Describe

Notes: Hydrology? Soils?

X011084_3538 1 December 2002

Attachment Wetland Assessment Office Data Sheet

DNR Basin

SNOHOMISH COUNTY DNR PROJECT - WETLAND ASSESSMENT OFFICE DATA SHEETBASIN:

Wetland ID Code

Wetland ID Number

Wetland Complex Number

Cowardin Class Previous Wetland Acreage

Existing Wetland Acreage

Change in Wetland Acreage

Connecting Stream (WRIA)

Connected to Fish Bearing

(Y or N)

Connected to Non-Fish

Bearing (Y or N)

Field Check (Y1, Y2 or N)

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X011084_3538 1 December 2002

Volume III.C Snohomish County

DNR Project Riparian Assessment Methods

��


Contents Page

1.0 Methodology........................................................................................................1-1 1.1 Office Inventory for Riparian Conditions....................................................1-1

1.1.1 Define Riparian Units..................................................................1-1 1.2 Large Woody Debris Assessment .............................................................1-2

1.2.1 Classify Riparian Conditions.......................................................1-2 1.2.2 Determine Riparian Unit Width ...................................................1-2 1.2.3 Assess Recruitment Potential Rating .........................................1-3 1.2.4 LWD Recruitment Potential ........................................................1-3

1.3 Shade Assessment....................................................................................1-4 1.3.1 Determine Target Shade Levels .................................................1-4 1.3.2 Determine Existing Shade Levels...............................................1-4 1.3.3 Field Measurement Of Stream Shading .....................................1-5 1.3.4 Identify Riparian Shade Hazard..................................................1-5 1.3.5 Attribute Data..............................................................................1-6 1.3.6 Assumptions ...............................................................................1-6

2.0 References...........................................................................................................2-1

Tables 1-1 Codes to Describe Vegetation Type 1-2 Riparian Width Categories 1-3 Recruitment Potential Ratings 1-4 LWD Recruitment Hazard Call 1-5 Riparian Target Shade (Canopy Closure) Values for Non-Glacial Streams in Western

Washington 1-6 Estimated Levels of Canopy Closure from Aerial Photos


1.0 Methodology Riparian areas within each DNR basin will be assessed according to several attributes, including vegetation type, tree size class, stand density, stand width, and stream shading. These attributes will be used to evaluate the potential for riparian areas to deliver large woody debris and to shade streams. The riparian assessment will consist of both office and field inventories. Riparian conditions will be assessed within 300 feet of Washington Department of Natural Resources Types 1, 2, and 3 (fish-bearing) streams that occur within Snohomish County Urban Growth Area (UGA) boundaries. Riparian conditions will not be assessed in incorporated areas (i.e., cities). Riparian conditions may be assessed in areas outside UGAs if there is a high potential for these areas to affect UGAs.

1.1 Office Inventory for Riparian Conditions The office inventory for riparian conditions will be conducted concurrently with the office inventory for wetlands using the same or similar 1998 aerial photograph-based maps overlain with existing inventory information available from the County. Base maps will be at a scale of 1 inch = 500 feet, utilizing a black and white photo base and color inventory information. Original 1995 high-resolution photos (1 inch = 400 feet) and 1991 stereo pairs (~1 inch=2000 feet) can be reviewed at the Public Works records office (first floor, Wall Street; 425/388-6453; Dave Evans, Supervisor).

Minimum information to be provided on the base maps includes:

• 1998 aerial photo • DNR basin and subbasin boundaries • UGA and City boundaries • Rosgen reach types for fish-bearing streams • Section corners

1.1.1 Define Riparian Units Divide the riparian areas along fish-bearing streams into riparian units (RUs). An RU is a portion of the riparian area for which riparian vegetation type, size, and density remain approximately the same. When riparian characteristics change, a new RU is defined. Each RU occurs on only one side of the stream (i.e., riparian areas on the opposite side of the stream are separate RUs). Major breaks are often associated with changes in land use, ownership, or dominant conditions in the unit (>70% of area). The minimum length of a RU shall be 500 feet. Delineate the RU breaks using short lines drawn perpendicular to the stream. Each RU is defined by the band of vegetation adjacent to streams. The width of this band will vary.

Assign each RU a unique number identifier. Begin numbering at the basin or subbasin outlet and proceed upstream along the primary stream first, then along each fish-bearing tributary. Distinguish left bank separately from right bank (Left Bank—left side when facing downstream; Right Bank—right side when facing downstream). Select alpha-numeric

X011084_3538 1.0 Methodology 1-1 December 2002

Riparian Assessment Methods

identifiers for RUs that are unique for each DNR basin. For example, A1L and A1R correspond to the left and right bank of RU1 in Allen Creek, respectively.

1.2 Large Woody Debris Assessment

1.2.1 Classify Riparian Conditions Record the riparian condition codes on the RU Spreadsheet using the system in Table 1-1 (Vegetation Type, Tree Size Class, and Stand Density). Each RU shall always have 3 letters assigned. For example, Riparian Unit AL1 may be classified as “CLD”, corresponding to Conifer, Large, Dense.

Table 1-1 Codes to Describe Vegetation Type

Vegetation Types C Mostly conifer trees (>70% of area) H Mostly deciduous trees (>70% of area) M Mixed conifer/deciduous trees B Shrub/brush species (>70% of area), including blackberry vines G Grass/meadow (>70% of area) N No riparian vegetation (>70% of area)

Tree Size Classes R Regeneration (<4-inch average diameter at breast height (DBH)) S Small (4- to 12-inch average DBH) L Large (>12-inch average DBH) N Nonforest (applies to vegetation Types B, G, and N)

Stand Density D Dense (<1/3 ground exposed) S Sparse (>1/3 ground exposed) N Nonforest (applies to vegetation Types B, G, and N)

Source: Modified from WFPB (1997) and OWEB 1999.

The accuracy of this method depends on the analyst’s ability to interpret riparian conditions from aerial photography. Confidence in the assessment can be increased by performing field checks of the preliminary photo estimates of riparian conditions as time allows. Survey RUs that represent a range of riparian conditions found in the basin (e.g., combinations of tree type, size, and density) and RUs where riparian conditions are indeterminate from the photos.

1.2.2 Determine Riparian Unit Width Estimate the width of the RU using a scale on the aerial photo basemap and categorize according to Table 1-2. The majority of functional wood is recruited within 100 feet (horizontal distance) or less of the stream’s edge (e.g., McDade et al., 1990).



Table 1-2. Riparian Width Categories

Stand Width N Narrow (<25 feet wide) M Medium (25 to 50 feet wide) W Wide (> 50 feet [if > 50 feet wide, then estimate approximate width])

1.2.3 Assess Recruitment Potential Rating Assign a recruitment potential rating according to Table 1-3 to each RU based on the riparian condition codes and record this rating in the spreadsheet.

Table 1-3. Recruitment Potential Ratings

Low CRD, CRS, CSD, CSS, HRD, HRS, HSD, HSS, MRD, MRS, MSD, MSS, HMS, HLS, BNN, GNN, NNN

Moderate CLS, HLD, MLS High MLD, CLD

1.2.4 LWD Recruitment Potential Using the matrix in Table 1-4, determine the LWD recruitment potential for each RU using (1) the LWD recruitment potential rating (Low, Moderate, High); and (2) the channel sensitivity rating (Low, Moderate, High). Record the recruitment potential for each RU on the RU Spreadsheet.

Table 1-4. LWD Recruitment Potential

Rating of Channel Sensitivity to LWD

Recruitment Potential Rating

Low (Rosgen channel

types: A, Aa+, X, W)

Moderate (Rosgen channel

type: B)

High (Rosgen channel types: C, E, F, G)

Low Low High* High

Moderate Low High* High*

High Low High* High*

*Ratings are based on the assumption that the in-channel LWD is off-target in most streams in the assessment area. Potentials with an asterisk may be modified to “Moderate” if stream survey data show that in-channel LWD is considered on-target.

Source: Modified from WFPB, 1997



1.3 Shade Assessment

1.3.1 Determine Target Shade Levels Use Table 1-5 to identify target shade values for sections of Class A and AA streams. Record the target shade value in the RU Spreadsheet.

Table 1-5 Riparian Target Shade (Canopy Closure) Values for Non-Glacial Streams in

Western Washington Elevation Zones (feet)

Minimum Shade Category (%) Class AA DOE Standard – 16

Class A DOE Standard - 18

50 1640-1960 680-1000 60 1160-1640 440-680 70 680-1160 120-440 80 320-680 <120 90 <320 N/A

Source: From WFPB, 1997

1.3.2 Determine Existing Shade Levels Existing shade levels are determined by analyzing the aerial photos. For the photograph analysis, use either 1 inch=400 feet photos or stereo pairs of the most recent photographs that cover the subject streams. Examine the riparian canopy cover and estimate the percentage of canopy shading to the nearest 10 percent. A general guide for shade estimates is contained in Table 1-6.

Record the target and existing shade estimates on the RU Spreadsheet for each RU. The accuracy of this method is strongly dependent on ground-truthing of photograph interpretations and review of any supplemental information (e.g., thermograph data) that may be available. First, preliminary estimates of riparian conditions are made in the office using the photographs and supplemental information. Field surveys are conducted as needed to check the accuracy of estimates for the representative areas selected. The analyst should focus on those stream reaches where their confidence in the photo calls was low. Use a spherical densiometer to make shade measurements at 50- to 100-foot intervals at selected sites. Determine the average shade from the densiometer measurements. Finally, record the existing and target shade codes on the working map.



Table 1-6 Estimated Levels of Canopy Closure from Aerial Photos

Stream surface not visible >90% shade Stream surface slightly visible or visible in patches 70-90% shade Stream surface visible but banks are not visible. 40-70% shade Stream surface visible and banks visible at times. 20-40%shade Stream surface and banks visible. 0-20% shade Source: From WFPB, 1997

1.3.3 Field Measurement Of Stream Shading At a minimum, stream shading shall be estimated qualitatively in the field. As resources allow, stream shading may also be measured in the field using the following approach modified from Schuett-Hames et al. (1994). Shade measurements should be taken approximately every 50 to 100 feet along the channel. Shade should be measured at a minimum of 3 points for each RU. The measurement at each point is an average of four systematic canopy closure readings taken in the middle of the channel.

Use a spherical densiometer to estimate shade to the stream channel at each point. To take a densiometer reading, hold the densiometer 12 to 18 inches in front of you at elbow height. Use the circular bubble-level to ensure that it is level. Look down on the surface of the densiometer, which has 24 squares etched into its reflective face. The reflection of the top of your head should just touch the outside of the grid. Imagine that each square is subdivided into four additional squares, so that there are 96 smaller quarter-squares. Envision a dot in the center of each quarter-square. Count the total number of quarter-square dots covered by the reflection of vegetation.

Four readings are made at each point. Begin with a reading facing directly upstream (Up); then turn clockwise 90 degrees and take a reading facing the left bank (LB); then turn another 90 degrees clockwise and take a reading facing downstream (Dn); and finally turn clockwise another 90 degrees and take a reading facing the right bank (RB). To determine shade, sum the number of quarter-square dots obscured with vegetation for all four readings, multiply the result by 1.04 (correction factor), and divide this result by 4. The result is the average percent shade at that point. Average the percent shade at all points to get the average percent shade for the RU. View into a convex spherical densiometer showing placement of head reflection and bubble-level. Visualize four spaced dots in each square and count the number covered by vegetation.

1.3.4 Identify Riparian Shade Hazard Hazard calls for shade are determined by comparing estimates of existing shade levels with target shade levels. High hazard calls apply where existing shade, estimated from photographs or field measurements, is less than the target value for that stream reach by more than 10 percent. Medium hazard calls apply where existing shade is 10 percent or less than the target value. Low hazard calls apply to those stream reaches where existing shade meets or exceeds target shade levels.



1.3.5 Attribute Data For each riparian unit, the analyst will record information in the RU Spreadsheet to be incorporated into GIS. Attribute data to be recorded include:

• Riparian unit identification code • Rosgen Stream Type • Rosgen Segment ID • RU length • Vegetation type • Tree size class • Stand density • RU width • Target shade • Existing shade • Riparian shade hazard • Presence of beaver ponds, dams, or complexes

The riparian field assessment will be conducted throughout each basin on a selective basis using information gathered in the office assessment of existing information. The field assessment will help characterize riparian functions to support fish habitat, and will focus on riparian stands that are candidates for habitat CIPs. In addition, the field assessment may be customized for each basin to best utilize the limited field assessment time, based on input from the County to focus on locations of concern. Information gathered from the field assessment will be provided to GIS to develop riparian maps showing RUs and riparian hazard calls.

1.3.6 Assumptions Office assessment of riparian conditions from aerial photos is assumed to equire approximately 1 hour/mile of stream length, and field assessment will average 1 hour/mile of stream length per DNR basin.



2.0 References

Washington Forest Practices Board (WFPB). 1997. Board Manual: Standard Methodology for Conducting Watershed Analysis. Under Chapter 222-22 WAC. Version 4.0. Washington Forest Practices Board. Olympia, WA. [November 1997]

McDade et al. 1990. Source Distances for Coarse Woody Debris Entering Small Streams in Western Oregon and Washington. Canadian Journal of Forest Research 20:326-330.

Oregon Watershed Enhancement Board (OWEB). 1999. Component V Riparian/Wetlands Assessment. Oregon Watershed Enhancement Board, Salem, OR. Available online at: http://www.oweb.state.or.us/publications/wa_manual99.shtml.

Schuett-Hames, D., A. Pleus, L. Bullchild, and S. Hall. 1994. Timber-Fish-Wildlife Ambient Monitoring Program Manual. Northwest Indian Fisheries Commission, Lacey, WA. TFW-AM9-94-001.

Attachment Riparian Field Data Sheet

Snohomish DNR Project Riparian Field Data Sheet

DNR Basin: Date:

Location:

Crew:

Riparian Unit (RU) #: Estimated Streamflow: ______cfs

Estimated Riparian Width: Rt. Bank ____ Left Bank____ Beaver ponds, dams? YES NO

Existing Stream Shade (qualitative / quantitative?) Upstream_____% Downstream______%

Riparian Wetlands Present? YES NO. Describe:

Riparian Vegetation—indicate dominant species (≥20% cover) with an asterisk (*).

Tree Species

Shrub Species Herbaceous Species

Riparian Condition

Vegetation Type: Upstream _____ Downstream_____

C Mostly conifer trees (>70% of area) H Mostly deciduous trees (>70% of

area) M Mixed conifer/deciduous trees B Shrub/brush species (>70% of area),

including blackberry vines G Grass/meadow (>70% of area) N No riparian vegetation (>70% of area)

Tree Size Class: Upstream _____ Downstream_____ R Regeneration (<4-inch average

DBH) S Small (4- to 12-inch average

DBH) L Large (>12-inch average DBH) N Nonforest (applies to vegetation

Types B, G, and N)

Stand Density: Upstream _____ Downstream _____ D Dense (<1/3 ground exposed) S Sparse (>1/3 ground exposed) N Nonforest (applies to vegetation

Types B, G, and N)

Disturbance? YES NO. Describe.

Photos? YES NO. Digital or Film (circle one). Photo Roll#__________ Photo Number(s)_____________ Describe:

Notes (potential restoration, enhancement, CIP?):

X011084_3538 1 December 2002

Snohomish DNR Project Riparian Field Data Sheet

X011084_3538 2 December 2002

Canopy Closure Field Worksheet A B C D

Station Upstream Left Bank Downstream Right Bank Stream Shade %*

Notes

0+00

* Stream Shade % = ((A + B+ C + D)*1.04)/4

Attachment Riparian Assessment Data Sheet

Basin Name

SNOHOMISH COUNTY DNR PROJECT - RIPARIAN ASSESSMENT DATA SHEET Y1=on-site checkBasin Name Y2=remote check

N=No check

RU ID Code

Left Bank or

Right Bank?

(LB/RB)

Rosgen Stream

Type

Rosgen Stream

ID#

RU Length

(ft)

Veg Type (C,H,M,B,

G,N)

Tree Size Class

(R,S,L,N)

Stand Density (D,S,N)

RU Width (N,M,W)

LWD Recruitm

ent Potential (L,M,H)

LWD Hazard

(H, M, L)

Target Shade

(%)

Existing Shade

(%)

Shade Hazard (H,M,L)

Presence of Beaver

Ponds, Dams, or Complex

es

DNR Stream ID

Code (WRIA)

Field Check

(Y1, Y2, N)

Instream Check (Y1, N)

Notes

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X011084_3538 1 December 2002

Volume III.D Culvert Assessment

Protocol for DNR Streams

��


Contents Page


1.0 Rationale ..............................................................................................................1-1

2.0 Field Computers and File Management ............................................................2-1

3.0 Field Equipment ..................................................................................................3-1

4.0 Culvert Assessment............................................................................................4-1

4.1 Level A Barrier Analysis ............................................................................4-1

4.2 Field Culvert Information ...........................................................................4-2

4.3 Field Measurements ..................................................................................4-2

4.4 Photographs ..............................................................................................4-3

5.0 Fishway and Dam Blockages.............................................................................5-1

5.1 Fishways....................................................................................................5-1

5.2 Dams .........................................................................................................5-1

6.0 Prioritization of Culvert CIPs..............................................................................6-1

7.0 General Recommendations................................................................................7-1

7.1 Photographs ..............................................................................................7-1

7.2 Available Resources..................................................................................7-1

8.0 References...........................................................................................................8-1



AAS Adopt-A-Stream CIP capital improvement project DNR Drainage Needs Report GIS Geographic Information System GPS Global Positioning System UGA Urban Growth Area WDFW Washington Department of Fish and Wildlife WDNR Washington Department of Natural Resources


1.0 Rationale During project development, the habitat team made several assumptions about fish distribution and culvert conditions within the Urban Growth Area (UGA) streams based on available information from existing County maps. The initial approach was to assess the headward extremes of all mapped salmonid distributions within the UGA channels (Washington Department of Natural Resources [WDNR] Type 1, 2, and 3 streams), determine if a fish blockage was present within this area, and if so, then assess habitat conditions above that blockage. After a habitat assessment was complete, a determination would be made if these blockages were potential capital improvement projects (CIPs).

Shortly after the project began, however, additional culvert data became available which required the habitat assessment team to reevaluate their culvert assessment approach. These data, made available for drainages in South Snohomish County by Washington Department of Fish and Wildlife (WDFW) and Adopt-A-Stream (AAS), indicate numerous fish blockages and suggest the anadromous fish distributions may not extend to the limits of the WDNR mapped Type 1, 2, and 3 streams. Additionally, the extent of blockages also suggests that drainages that did not receive the WDFW and AAS assessment may have several culverts that may be fish blockages as well.

After several conversations with County and Consultant staff, we have developed a protocol that will help prioritize significant blockages to fish passage and provide a list of potential CIPs for their repair. During field investigations, the teams will encounter drainages that have either not been previously assessed for blockages, or have been assessed but may have unmapped blockages. In these areas, the team will perform a rapid passage assessment based on the WDFW’s Level A approach for culverts and WDFW methods for non-culvert blockages (e.g., dams, bedrock-dominated shallow glides, cascades, etc.) (WDFW, 2000). All blockages will be prioritized by the methodologies articulated below and a potential early action or major repair CIP list will be developed.

X011084_3538 1.0 Rationale 1-1 December 2002

2.0 Field Computers and File Management During the survey, data will be entered into a spreadsheet database contained on a field computer or on hard copy datasheets and then summarized onto one electronic datasheet later. The datasheet is named Culvert_1.0.xls. It is recommended that the hardcopy datasheet be filled out in the field for each potential blockage and summarized in the electronic form later. The hardcopy datasheet contains additional information that is not necessary for the electronic database and will help each team develop and document the rationale for their professional judgments. The County will use this Level A assessment to establish a fish passage database along with the team’s repair recommendations. The information in the electronic database will be used for Level B assessments.

The datasheets will also be useful for describing non-culvert barriers found in the field. These datasheets, like the qualitative datasheets, will help the field teams develop and document the rationale for their professional judgment and determination of CIP lists.


3.0 Field Equipment • Field computer

• A stadia rod or wading stick per team member

• Measuring tape

• Hip chain

• Abney level

• Global Positioning System (GPS)

• Several copies of datasheets


4.0 Culvert Assessment When a culvert that has not been previously assessed is encountered, the habitat team will perform a WDFW Level A culvert assessment. The Level A assessment is relatively simple and is explained in the dichotomous key below. The key will determine if the culvert is a barrier, not a barrier, or unknown. If the determination leads to an unknown status, the assessment team will use their best professional judgment to determine the extent of a potential blockage and will recommend that future Level B assessments occur on the culvert. The assessment team will not perform Level B assessment during this project.

Prior to conducting this assessment, each team should download and print the WDFW manual from the WDFW website (www.wa.gov/wdfw/hab/engineer/fishbarr.htm [PDF format]). Several portions of this protocol are taken directly from the WDFW approach, and the manual provides additional details and clarification.

4.1 Level A Barrier Analysis (WDFW, 2000) A. Is there natural streambed material throughout the culvert?

a. If yes, is the culvert width (span) at least 75 percent of the average streambed toe width at the second riffle downstream of the culvert (representative riffle)?

i. If yes, the culvert is not a barrier, additional measurements not required.

ii. If no, go to B.

b. If no, is there an outfall > 0.24 meters?

i. If yes, the culvert is a barrier, additional measurements not required.

ii. If no, is the culvert slope > 1 percent?

1. If yes, the culvert is a barrier, additional measurements not required.

2. If no, go to B.

B. Is there a grade break in the culvert?

a. If yes, then the barrier status is unknown and a Level B analysis is not possible.

b. If no, then go to C.

C. Is the culvert tidally influenced or is there a large pond or wetland downstream of the culvert making it difficult or impossible to obtain the downstream control cross-section information?

X011084_3538 4.0 Culvert Assessment 4-1 December 2002

Culvert Assessment Protocol for DNR Streams

a. If yes, then the barrier status is unknown and a Level B analysis is not possible.

b. If no, go to D.

D. Barrier status is unknown, a future Level B analysis will be required.

Grade breaks occur in cases where culverts have been extended and the new section is installed at a different elevation or slope than the old culvert. This can also occur when a section of culvert settles or a joint fails. In cases where the slope of any portion of the culvert exceeds 1 percent or the drop inside the culvert exceeds 0.24 meters, then it can be categorized as a barrier. If the slope does not exceed 1 percent or the drop does not exceed 0.24 meters, of if these parameters cannot be measured, then the barrier status of the culvert is unknown and a higher level of analysis is required.

4.2 Field Culvert Information The field datasheet requires the team to collect a suite of location and structural information that will later be used for a culvert database and for future analysis. The header information of the datasheet provides location information. It is important that the culvert is located by street crossing or by GPS. Once the location is acquired, all of the additional information required for the WDFW database can be extracted from GIS databases.

Culvert structural information is self-explanatory from the datasheet. This information is important for the WDFW database and for future analysis.

4.3 Field Measurements There are very few measurements required in the field. They are as follows:

1. Measure the length of the culvert in meters (m).

2. Assess if natural streambed is present throughout the culvert.

3. Measure the horizontal span of the culvert at the downstream side.

4. Measure the average streambed toe width at the second riffle downstream of the culvert. The streambed toe is defined by WDFW as the bottom of each bank and in some cases can be below the wetted surface elevation.

5. Measure the outfall drop from the top of the water in the culvert to the top of the water downstream of the culvert to the nearest 0.01 m.

6. Measure the slope of the culvert from the culvert upstream invert elevation to the culvert downstream invert elevation in percentage ((USIE-DSIE)/Length*100 = Slope). This can be done with an Abney level, or a bubble level and two wading/stadia rods. The WDFW manual states that clinometers are not acceptable for slope measurements.


Culvert Assessment Protocol for DNR Streams

4.4 Photographs All culverts that receive an unknown or barrier status should have a photograph. These photographs will help the teams later determine the significance of each blockage and provide an eventual CIP list. Keep track of photograph and roll numbers on the data sheet.


5.0 Fishway and Dam Blockages Below is a brief description of fishway and dam blockages summarized from the WDFW manual. It is intended to help the field teams with their professional judgement of fish blockages. Again, the field teams should familiarize themselves with the WDFW manual.

5.1 Fishways A fishway is any human-made structure that facilitates the passage of fish through or over a barrier. As fishways frequently fail or are poorly designed, WDFW recommends that fishways be assessed as dams.

5.2 Dams A dam is any human-made structure that results in an abrupt change in water surface elevation. WDFW states that a water surface difference greater than 0.24 m is a block to chum and 0.30 m is a block to all other fish. Dams with standpipes are always barriers.

X011084_3538 5.0 Fishway and Dam Blockages 5-1 December 2002

6.0 Prioritization of Culvert CIPs For all areas that have been previously assessed by WDFW or AAS, the field team will examine all blockages within the channel. It is important that the ecologists see the blockages and assess the potential for repair. The field team should have, or will have, knowledge of upstream habitat above the culvert and will use their professional judgement to prioritize the culvert repair.

The WDFW provides a fish passage priority index that consolidates many factors that affect a project’s feasibility (expected passage improvement, production potential of the blocked stream, fish stock health, etc.) into a framework for developing prioritized lists of projects. This index will be useful for a region-wide CIP development; however, for each basin we will follow a simple prioritization approach coupled with professional judgement:

1. Blockages in fish-barring channels are important.

2. Blockages lower down in the drainage are more important than higher blockages.

3. Full blockages are more important than partial blockages.

X011084_3538 6.0 Prioritization of Culvert CIPs 6-1 December 2002

7.0 General Recommendations

7.1 Photographs All culverts, dams, or fishways that receive an unknown or barrier status should be photographed. These photographs will help the teams later to determine the significance of each blockage and provide an eventual CIP list. Record photograph and roll numbers on the data sheet.

7.2 Available Resources The WDFW web site mentioned above is very helpful with questions about fish possibility. Other resources include:

• A Catalog of Washington Streams and Salmon Utilization (Williams et al., 1975)

• Tri-County Salmon Information web site (http://www.salmoninfo.org/)

• Forest Service Fish Xing web site (http://www.stream.fs.fed.us/fishxing/index.html)

X011084_3538 7.0 General Recommendations 7-1 December 2002

8.0 References

WDFW. 2000. Fish Passage Barrier and Surface Water Diversion Screening Assessment and Prioritization Manual. WDFW Habitat Program Environmental Restoration Division: Salmonid Screening, Habitat Enhancement, and Restoration (SSHEAR) Section. Olympia, WA.

Williams, R. W., R. M. Laramie, and J. J. Ames. 1975. A Catalog of Washington Streams and Salmon Utilization. Vol. 1. – Puget Sound. Wash. Dept. Fish. Olympia, WA.


Attachment Fish Passage Assessment Data Sheet

Snohomish County Drainage Needs Fish Passage Assessment Date:Team Name:Sub Basin:Stream Name:Reach ID Number:Rosgen Class:Feature TypeFeature Location:Lat:Long:Culvert Previously Assessed? Culvert Shape (RND,BOX,ARCH, SQSH,ELL,OTH)Culvert Material (PCC,CPC,CST,SST,CAL,SPS,SPA,PVC,TMB,MRY,OTH)Streambed material throughout the length of Culvert (y/n)?Culvert span in metersBankfull Width of second riffle down stream from culvert in meters Span/bankfull*100Outfall Drop in metersCulvert slopeCulvert Status

X011084_3538 December 2002

Volume III.E B-IBI Sampling Protocol for

DNR Streams

��


Contents Page


1.0 Rationale ..............................................................................................................1-1

2.0 Data Management ...............................................................................................2-1

3.0 Field Equipment ..................................................................................................3-1

4.0 Site Selection.......................................................................................................4-1

5.0 Invertebrate Collection .......................................................................................5-1 5.1 Archive Sample .........................................................................................5-1 5.2 Collect Replicate Samples.........................................................................5-2

6.0 General Recommendations................................................................................6-1 6.1 Existing Data .............................................................................................6-1 6.2 Available Resources..................................................................................6-1

7.0 References...........................................................................................................7-1

Appendix

A Sites Currently Sampled by Snohomish County



B-IBI benthic index of biotic integrity CIP capital improvement project DNR Drainage Needs Report UGA Urban Growth Area


1.0 Rationale A measure of biotic integrity will be used to quantify the cumulative impacts of development on the ecosystem and the level of degradation relative to a range of watershed conditions within the Puget Sound lowlands. The benthic index of biotic integrity (B-IBI) for Puget Sound lowland streams (Kleindl, 1995), which quantifies the overall biotic condition of a stream based on measuring attributes of benthic macroinvertebrates, has been selected because B-IBI scores have been shown to correlate well with levels of urbanization (Fore et al., 1996; Horner et al., 1996). The protocol described below is from Biological Monitoring and Assessment: Using Multimetric Indexes Effectively (Karr and Chu, 1997).

X011084_3538 1.0 Rationale 1-1 December 2002

2.0 Data Management During the B-IBI sampling, site location data and site selection rationale shall be recorded onto one electronic datasheet for each DNR area. This information can be collected in a field notebook and recorded onto the B-IBI summary sheet later, or entered directly with the field computer. The B-IBI summary sheet is named BIBI_1.0.xls.

X011084_3538 2.0 Data Management 2-1 December 2002

3.0 Field Equipment • 500 micron mesh Surber type sampler

• 500 micron (or smaller) mesh sieve

• Flagged weight to identify sample location

• Ethyl alcohol (95%)

• Two 1-liter squirt bottles for alcohol

• Garden trowel or large spike to disturb substrate

• White bucket or white wash bin to empty sample from Surber

• Large cup with handle to rinse invertebrates off Surber

• Stop watch

• Forceps (tweezers)

• Plastic spatula

• Waterproof ("Rite-in-the-rain") paper

• Pencil, permanent marker (Sharpie), and grease pencil

• 250 ml screw-top jars (3 per sample site)

• Ziploc bags


4.0 Site Selection Sample sites need to be representative of the larger study area. Physiographic characteristics like vegetation, soils, geology, land use, gradient, riparian characteristics, and substrate need to be considered to assure that sample sites are representative of the larger population. Work with County basin stewards to select sites that are appropriate, or use professional judgement to determine appropriate sites. A list of previously sampled sites within the County is attached to this protocol.

After a stream reach is selected, find a riffle long enough to accommodate three replicate samples. Ideal sampling locations consist of rocks 5 to 10 cm in diameter sitting on top of pebbles. Substrates dominated by rocks larger than 50 cm in diameter should be avoided.

Sample sites should not be directly downstream from anomalies such as culverts, bridges, roads, landslides, or waterfalls unless these are the conditions that the monitoring program is evaluating. If unavoidable, sample at least 50 m upstream of a bridge and 200 m (more would be better) downstream of a bridge.

Record exact location of the sample site.

X011084_3538 4.0 Site Selection 4-1 December 2002

5.0 Invertebrate Collection

Three total replicates will be taken from each sample location using the following methodology:

1. Sample within the main flow of the stream. Sample at water depths of 10 to 40 cm. Depth, flow, and substrate type should be similar for the three replicate samples collected in the riffle. Begin sampling downstream and proceed upstream for the three replicates.

2. Place Surber sampler on the selected spot with the opening of the nylon net facing upstream. Brace the frame and hold it firmly on the stream bottom.

3. Lift the larger rocks resting within the frame and brush off crawling or loosely attached organisms so that they drift into the net. After "cleaning" the rocks, inspect for invertebrates and discard from sampling area.

4. Once the larger rocks are removed, disturb the substrate vigorously with a trowel or large spike for 60 seconds. This disturbance should extend to a depth of about 10 cm to loosen organisms in the interstitial spaces, washing them into the net.

5. Lift Surber out of the water and tilt the net up and out of the water while keeping the open end upstream. This helps to wash the organisms into the receptacle. Drop a piece of weighted flagging tape to mark the location of the first replicate sample. Do not step on remaining sample areas while walking to stream bank.

6. On the stream bank, empty contents of Surber into large bucket or wash bin. Remove all animals and debris from Surber sampler.

7. Separate benthic macro-invertebrates from the substrate by stirring the contents of the plastic wash pan. Pour floating organic matter into a 500-µm soil sieve then transfer into a sampling jar and preserve with ethanol (95 percent). Residual water in the sample will dilute the ethanol to about 70 percent.

8. Repeat rinsing and pouring into the 500-µm soil sieve until all apparent animals are removed from gravel. Add a small amount of water to remaining gravel and set aside for a few moments. Remaining invertebrates will begin to move among the substrate. Use a magnifying glass and tweezers to remove the remaining animals and place directly into the sample jar.

5.1 Archive Sample Insert a sample label that contains name of team, date, location, and sample number and replicate number into the jar. Fill the sample jar to the top with alcohol and seal. Write the location and date on top of the sample lid. Place the jar in a Ziploc bag labeled with the same information.

X011084_3538 5.0 Invertebrate Collection 5-1 December 2002

B-IBI Sampling Protocol for DNR Streams

5.2 Collect Replicate Samples Return to the location of the first sample, walk upstream, and collect another sample of invertebrates. Leave another flagged marker and process the sample as above. Repeat this process once more for a total of three replicate samples from each site location. Each replicate should be labeled (e.g., #1, #2, #3) and archived separately.

X011084_3538 5.0 Invertebrate Collection 5-2 December 2002

6.0 General Recommendations

6.1 Existing Data For historic sampling locations and results, go to Salmonweb, a website devoted to B-IBI in the Puget Sound lowlands (http://www.salmonweb.org/). Once at the site, click on “Interactive Stream Maps,” then “Monitoring Site Index,” then scroll to the desired basin for sampled locations and click on the site of the scores. Also see Appendix A for a list of sample sites that were supplied by Snohomish County. Direct all questions about this appendix to the County.

6.2 Available Resources The Salmonweb site is very helpful with questions about B-IBI in the Puget Sound lowlands (http://www.salmonweb.org/). Other useful publications include:

May, C.W., E. B. White, R. R. Horner, J. R. Karr, and B. W. Mar. 1997. Quality Indices for Urbanization Effects in Puget Sound Lowland Streams. Water Resources Series Technical Report No. 154. Washington Department of Ecology. Publication Number 98-04. Olympia, WA.

Washington Department of Ecology (Ecology). 1999. The Relationship Between Stream Macroinvertebrates and Salmon in the Quilceda/Allen Drainages. Publication Number 99-311. Olympia, WA.

X011084_3538 6.0 General Recommendations 6-1 December 2002

7.0 References Fore, L. S., J. R. Karr, and R. Wisseman. 1996. Assessing Invertebrate Responses to

Human Activities: Evaluating Alternative Approaches. Journal of the North American Benthological Society 15(2):212-231.

Horner, R. R., D. B. Booth, A. Azous, and C. W. May. 1996. Watershed Determinants of Ecosystem Functioning. Proceedings of an Engineering Foundation Conference. American Society of Civil Engineers, Snowbird, UT.

Karr J. R. and E. W. Chu. 1997. Biological Monitoring and Assessment: Using Multimetric Indexes Effectively. Seattle, WA: University of Washington.

Kleindl, W. J. 1995. A Benthic Index of Biotic Integrity for Puget Sound Lowland Streams, Washington, USA. M.S. Thesis, University of Washington. Seattle, WA.


��

B-IBI Sampling Protocol for DNR Streams

APPENDIX A

Sites Currently Sampled by Snohomish County

Appendix A

Table A-1 Sites Currently Sampled by Snohomish County

Benthic Invertebrate Survey 1997B-IBI

1998B-IBI

1999 B-IBI

2000B-IBI Site Location

Stillaguamish Watershed Fish Creek 30 28 WQ site fish Pilchuck Creek 24 28 WQ site pilc Church Creek 28 28 WQ site cckpk Riley Creek 30 Upstream of Jim Creek Road Snohomish Watershed Wallace River 30 May Creek 42 Cemetery Creek (Snohomish trib) 28 Steward project, 85th, S of

72nd on mainstem French Creek Watershed French Creek gage 38 36 WQ site fclu French Creek, upper mainstem, Meadowlake Road.

34 S of 84th St. SE

French Creek, mid mainstem, Trombley

38 Downstream of horse crossing

French Creek, lower mainstem, 159th

30 Mainstem – 159th

Cripple Creek 32 32 Upstream of 179th Spada Creek 40 Trombley and Spada Golf Course Creek 36 Downstream of Westwick

Road Chain Lake Creek 18 Trombley and Chain L Road Woods Creek Watershed Upper Woods Creek 26 Off Woods Creek Road Woods Creek – Lake Rosiger 3 Outlet from Lk Rosiger, above

confluence w/ Woods Creek Woods Creek – Pipeline Road 22 E of 21st Ave. SE Woods Creek – Bridge 298 34 Bridge 298, S of powerline Woods Creek mainstem 34 28 WQ site wcms Woods Creek west fork 26 34 WQ site wcwf Woods Creek lower mainstem 24 Buck Island Park Carpenter Creek downstream 38 Creswell Road Carpenter Creek upstream 34 Sanders Road Friar Creek 34 Upstream of 104th St. SE

X011084_3538 Sites Currently Sampled by Snohomish County A-1 December 2002

Appendix A

Table A-1 Sites currently sampled by Snohomish County (continued)

Benthic Invertebrate survey 1997B-IBI

1998B-IBI

1999 B-IBI

2000B-IBI Site location

Pilchuck River Watershed Pilchuck River mouth 24 Snohomish City Park, S of

92nd St. SE Pilchuck R – 28th Pl. NE 26 28 Pl. NE, off Russell Road Pilchuck R – Snohomish Bridge 304 20 WQ site pilc Little Pilchuck Creek 34 WQ site lpil Catherine Creek 26 WQ site cath Dubuque Creek 32 WQ site dubq Panther Creek 26 30 Upstream of 16th St. SE Bunk Foss 14 Downstream of culvert on

Machias Road Sexton Creek 26 Upstream of 131st Ave. SE Quilceda/Allen Watershed Munson Creek 16 24 Grove St. past 69th Quilceda middle fork 30 30 Wade Road, Centennial Trail South County Watershed Norma Creek 20 18 WQ site psld North Creek gage 18 16 WQ site ncld, UW site Swamp Creek gage 22 20 WQ site scld Little Bear Watershed Little Bear upstream 34 34 30 WQ site lblu, UW site Little Bear downstream 30 28 30 WQ site lbld, UW site Little Bear headwaters 34 WQ site lbhw Trout Stream 34 WQ site trot Great Dane Creek 34 WQ site dane Cutthroat Creek 34 WQ site cutt Little Bear near mouth 28 Woodinville site lwcc Project evaluation – ag BMPs Trib 30 – 220th (Stillaguamish trib) 32 32 34 32 Reference site Trib 30 – Silvana Terrace 28 30 36 32 Reference site, WQ site tr30 Trib 30 – mouth 26 pre 28 pre 34 post 30 post Headrick project evaluation,

WQ site t30a, Trib 30 – channel 24 post 20 post Constructed channel, middle of

Headrick project


Appendix A


Table A-1 Sites currently sampled by Snohomish County (continued)

Benthic Invertebrate survey 1997B-IBI

1998B-IBI

1999 B-IBI

2000B-IBI Site location

Trib 33 20 pre 22 pre 20 post 18 post Tatum project evaluation, WQ site t33

Trib 31 22 pre 28 post 28 post 28 post Neff project evaluation, WQ site t31

Oso fencing project (Stillaguamish trib)

24 pre 26 post 28 post BMP evaluation, SCD project, 179th St. off Hwy 530

Stables Creek project (French Creek)

28 pre 38 post BMP evaluation, 96th St. SE

Attachment B-IBI Data Sheet

Snohomish County DNR B-IBI Site 1 Site 2 Site 3 Site 4 Etc.Date:Team Name:Sub Basin:Stream Name:Reach ID Number:Rosgen Class:Site LocationLat:Long:Comments:

X011084_3538 December 2002

Volume IV Water Quality Analysis

Protocols

December 2002

��



425-388-3464

Introduction The Water Quality protocols for the Drainage Needs Reports project consist of two elements, listed below, which are presented here in Volume IV of the DNR Protocols.

VOLUME IV.A Protocols for Preparation of Water Quality Pre-Draft Report Sections

VOLUME IV.B Guidance on Stormwater Quality Improvement Options

Introduction INTRODUCTION - WATER QUALITY.DOC 1-1 December 2002

Volume IV.A Snohomish County

Drainage Needs Report Protocols for Preparation of

Water Quality Pre-Draft Report Sections

��


Contents 1.0 Analysis of Water Quality Conditions and Identification of Problems.......................1-1

1.1 Introduction............................................................................................................1-1 1.2 Sources of Information to Characterize Water Quality Conditions ........................1-1

1.2.1 Reports and Data....................................................................................1-1 1.2.2 Field Reconnaissance ............................................................................1-3

1.3 Identification of General and Specific Problems....................................................1-3 1.4 Pre-Draft Report Contents.....................................................................................1-4

1.4.1 Report Graphics......................................................................................1-5

Tables Table 1. Potential Sources of Pollutants in Runoff ..............................................................1-6 Table 2. Pollutant Loading Ranges a for Various Land Uses. .............................................1-7

1.0 Analysis of Water Quality Conditions and Identification of Problems

1.1 Introduction The water quality analysis will vary for each DNR area depending upon several factors including the availability of existing information and data, the extent of water quality degradation that is occurring, and the potential for implementing water quality improvements. Although the individual drainage needs reports will vary in the level of detail presented for the water quality analysis, there are common technical analysis procedures and documentation formats that must be followed by everyone on the water quality analysis team to ensure consistency.

1.2 Sources of Information to Characterize Water Quality Conditions

1.2.1 Reports and Data The water quality analysts for each DNR area will gather available reports, water quality complaint documentation, water quality data, and relevant information primarily based on guidance from Kathy Thornburgh and Maureen Meehan of Snohomish County Surface Water Management, and other staff that they may defer to. The following publications and data may be relevant to some or all of the DNR areas:

• The State of the Waters: Water Quality in Snohomish County’s Rivers, Streams, and Lakes (2000) provides an excellent overview of water quality issues in the various DNR areas

• Basin plan reports have been prepared for Swamp Creek and North Creek, though they are now several years old

• A watershed management plan report was prepared for Quilceda and Allen Creeks by the county in 1999

• For drainage areas tributary to the Snohomish River, a potentially useful reference document is the Department of Ecology’s Water Quality Assessment of Tributaries to the Snohomish River and Nonpoint Source Pollution TMDL Study (1997)

• The Snohomish County Groundwater Management Plan (1999), available on the Surface Water Management web site, contains information that may be relevant to planning for stormwater infiltration in the various DNR areas

• The county has collected water quality monitoring data in several streams, often at an upstream location and a downstream location.

Extra copies of the State of the Waters report and Quilceda/Allen Watershed Management Plan report should be available from county staff, and these documents can also be accessed on the Surface Water Management web site. Herrera Environmental Consultants has obtained a copy

X011084_3538 1.0 Analysis of Water Quality Conditions and Identification of Problems 1-1 December 2002

Protocols for Preparation of Water Quality Pre-Draft Report Sections

of the Snohomish River tributaries assessment report, and can make additional copies for those who need them on. Herrera has also obtained the raw water quality data for all of the county’s stream sampling sites from Kathy Thornburgh, and can provide the associated electronic files to others on the team.

In addition to the sources of information listed above, more detailed information will be needed to refine the understanding of specific problem areas. Thus, many other sources of information also need to be gathered and reviewed. Once the analysts feel they have gathered all of the available information that the county can offer, and that they have found on their own, the analysts will compile a list of the various sources of information they are relying upon for each DNR area and submit it to Kathy Thornburgh to enable confirmation that nothing has been missed.

If relevant information is readily available from other sources besides those suggested by Kathy Thornburgh and Maureen Meehan, the DNR analysts are obligated to collect that information on their own and include it in the list of sources submitted to Kathy Thornburgh. Other sources of information that may prove useful include the following:

• Department of Ecology on-line database of NPDES stormwater permittees

• Anecdotal observations provided by Snohomish County survey crews

• Anecdotal observations provided by stream and wetland habitat field crews

• Benthic invertebrate population data collected by stream habitat field crews

• Unpublished water quality and benthic invertebrate data collected by Native American tribes and the University of Washington.

Maureen Meehan has also developed maps indicating the results of a 3-year outfall screening study. The maps summarize the findings of three consecutive years of dry weather inspections at various storm drain outfalls throughout many of the UGA areas. In many cases these inspections have revealed pollution problems that should lead to specific water quality improvement recommendations in those areas. Some of the DNR areas do not contain any of the drainage outfalls incorporated in this study, but most of the DNR areas should contain at least a few of the outfalls. These maps will be posted on the project web site.

Another potentially useful source of information to enable better understanding of potential sources of pollution is the county's tax assessment database that includes land use codes tied to parcel numbers. TerraLogic GIS will join these codes to the County's digital parcel layer (the integrated land records) to geographically locate the precise location of the land use. Once this is done, land uses can be aggregated within sub-basins and other study areas, both geographically and by total area, based on their relative potential to contribute to stormwater runoff pollution. From this GIS database, both tabular summaries and maps can be produced.

Several groupings of land use codes will be created to simplify the GIS database, while not sacrificing the ability to visualize sources of runoff pollution. For instance, certain industrial land uses and automotive-related businesses that are likely to be the greatest contributors to runoff pollutant loadings can be highlighted on these GIS maps in bright red, assorted commercial areas that are a potential problem but not as severe as those industrial and automotive land uses can be highlighted in pink, residential areas can be highlighted in light orange, etc. The water quality analysts in each DNR area are expected to coordinate with TerraLogic GIS to request one set of these hard copy maps for their study area(s), and a common basis for land use groupings and shading or color coding will be applied as agreed upon by TerraLogic GIS and the water quality technical lead, Mark Ewbank.



1.2.2 Field Reconnaissance The water quality analysts in the respective DNR areas will rely in part upon field reconnaissance to identify specific problems. It is expected that the available reports and data will provide a general indication of widespread water quality problems, but the reconnaissance can aid in determining specific problems that should be addressed. The field reconnaissance should focus on areas with relatively greater potential to contribute to water quality problems, with the GIS maps discussed previously offering clues to geographic areas of interest.

The field reconnaissance (supplemented by discussions with others who have already been in the field) should seek to identify the following types of drainage conditions, polluting activities, and related water quality impairment:

• Livestock access to the banks of streams and drainage channels

• Evidence of herbicide applications near drainage ditches and channels

• Eroding drainage ditches and channels

• Lack of vegetation buffers along ditches and channels (i.e., urban or agricultural runoff enters the channel without opportunity for infiltration or filtering)

• Storm drain inlets clogged with sediments and drainage channels filled with sediments

• Businesses and residences where outdoor activities are clearly contributing to runoff pollution – such as auto repair work in the street, washing of vehicles and equipment in paved areas near drainage systems, stockpiling of soil or other erodible raw materials in areas close to drainage systems that are unprotected with BMPs, and storing containers of fuel, chemicals, etc. in unprotected areas

• Point source discharges to drainage systems that seem suspicious

• Other obvious signs of pollution.

These observations may result in identification of specific water quality problem locations.

Although the pre-draft reports will not include discussion of potential improvements, the field reconnaissance should also involve looking for CIP sites. Examples include roadside ditches that could be converted to bioswales, detention ponds that could be expanded to provide wet pond storage, and large non-wetland depressions where runoff infiltrates.

1.3 Identification of General and Specific Problems The combination of available water quality data and GIS land use information should enable the characterization of general water quality problems (existing and future) and the sources of those problems. Examples of general problems include:

• High levels of fecal coliform bacteria in a stream due to livestock at numerous farms in close proximity to the stream channel

• Increasing phosphorus loadings in runoff due to expansion of lawn areas with single family residential development in a drainage area tributary to a lake

• High loadings of metals in a stream due to extensive roads and parking lots in the drainage area.

Table 1 provides a listing of pollutants versus the types of activities and land uses that may be the sources. This table may be of use in tracing problems to sources. Table 2 provides a



general comparison of average annual pollutant loadings per acre of different land uses. This table can be used to assess whether observed water quality is following trends that match the contributing land use. If observed concentrations of a particular pollutant seem unusual given the pollutant loading trends listed in Table 2, the DNR water quality analyst may be able to determine the approximate type(s) or location of business(es) or land owner(s) that are the specific source(s) of that pollutant. Table 1 can support this type of investigative work.

To the extent possible, given the data and budget constraints, the available water quality data for each DNR area will be analyzed to assess spatial trends – i.e., to determine if certain drainage areas are major contributors to water quality problems. If those areas can be identified, the subsequent CIP analyses can prioritize associated improvements for them. If the outfall screening results indicates that pollution problems were found in all 3 years of dry weather inspections at a particular location, it can be inferred that the contributing drainage area contains one or more specific problem sources. Specific problem locations observed during the field reconnaissance should be given a unique designation for further analysis. Examples of the types of specific problems that may occur are listed above in the discussion of field reconnaissance efforts.

For DNR areas located near a state highway, the Washington State Department of Transportation (WSDOT) drainage outfall inventory may be helpful in identifying highway runoff discharge problem locations that could be contributing to observed water quality problems. This inventory is keyed to state route number and milepost, and is not publicly accessible. Therefore, requests for information from this inventory need to be made to WSDOT staff. To minimize repeated requests to WSDOT, water quality analysts should forward their requests to the technical resource lead, Mark Ewbank of Herrera Environmental Consultants. Problem highway outfalls may also offer opportunities for joint CIP projects between Snohomish County and WSDOT.

1.4 Pre-Draft Report Contents The pre-draft water quality report for each DNR area will encompass several sections of the final DNR outline. Specifically, Appendix D of each final DNR report will provide the details of the water quality analysis for that DNR area. The water quality pre-draft report for each DNR area (except for the small UGAs) will be prepared in a format that can be readily incorporated into Appendix D at a later stage of the project. The outline for the water quality pre-draft reports is as follows:

Title = Pre-Draft Report for the ___ DNR Area Introduction

Land use patterns affecting water quality Percent impervious surface cover in the DNR area Availability of water quality information (discuss relative extent of info available)

Analysis methods (description of technical approach) Water quality data sources Field reconnaissance Coordination with county staff and other analyses

Water quality characterization Water quality conditions (general overview – good, bad, average)



Available water quality data - details Outfall screening results Expectations for future water quality (existing quality + implications with land use buildout)

Water quality problems General water quality problems (not specific to a particular location)

General problem #1 Description of problem and suspected source(s)

General problem #2 Description of problem and suspected source(s)

Etc. Basin No. 1

Specific water quality problem #1A Description of problem and suspected source(s)

Specific water quality problem #1B Description of problem and suspected source(s)

Etc. Basin No. 2

Specific water quality problem #2A Description of problem and suspected source(s)

Specific water quality problem #2B Description of problem and suspected source(s)

Etc.

1.4.1 Report Graphics The project scope of work does not provide geographic information systems (GIS) support for the water quality analyses. Thus, specific GIS-based graphics for the water quality pre-draft reports are not anticipated. To the extent possible, the graphics used in documenting the water quality analyses shall make use of the GIS maps and electronic files prepared for other purposes on the project. Individual report authors are free to use other graphics software as needed, provided that consistent map scales and styles are employed in the various report sections.

At a minimum, each pre-draft report should contain a vicinity map, a map indicating water quality sampling station locations, a map indicating the outfall screening stations, and a map indicating specific problem areas.



Table 1. Potential Sources of Pollutants in Runoff Pollutant / Water Quality

Problem Automobiles/Roads Commercial Industrial/Other Residential

Copper Brake linings, metal corrosion, clutch plates

Building materials (flashing), insecticides, fungicides

Paint, wood preservatives, electroplating, algicides, auto scrap yards

Flashing, insecticides, fungicides

Zinc Tire wear, motor oil, metal corrosion

Flashing, downspouts, gutters, moss retardants

Paint, wood preservatives, galvanizing, metal corrosion, auto scrap yards

Flashing, downspouts, gutters, moss retardants

Fecal coliform bacteria Septic system failures, fertilizers, sewer cross-connections to drainage systems

Animal and livestock wastes, agricultural use of manure, livestock access to stream and drainage channels

Pet wastes, failing septic systems

Polycyclic aromatic hydrocarbons (PAHs)

Gasoline, oil, grease, asphalt Roofing tar Wood preservative, wood/coal combustion

Roofing tar

Phosphorus Motor oil Detergents, fertilizers Detergents, soil erosion, decaying leaves and other vegetation

Fertilizers, detergents, pet wastes, failing septic systems, soil erosion

Suspended solids / turbidity Mud tracked on tires, particle washoff from vehicle undercarriages, traction grit

Stockpiles of erodible materials

Soil erosion, stockpiles of erodible materials

Soil erosion

Low dissolved oxygen Gasoline, diesel fuel, engine fluids

Human and animal wastes, chemicals, soil erosion

Pet wastes, pesticides, soil erosion

Low pH Chemical acids

High pH Concrete slurry Concrete slurry, chemical bases

Sources:

U.S. EPA. 1990. Urban targeting and BMP selection.

Horner et al. 1994. Fundamentals of urban runoff management, technical and institutional issues.



Table 2. Pollutant Loading Ranges a for Various Land Uses. Land Use TSS TP TN Pb Zn Cu FC COD

Road 281 0.59 1.3 0.49 0.18 0.03 7.1E+07 112

723 1.50 3.5 1.10 0.45 0.09 2.8E+08 289

502 1.10 2.4 0.78 0.31 0.06 1.8E+08 201

Commercial 242 0.69 1.6. 1.60 1.70 1.10 1.7E+09 306

1,369 0.91 84 4.70 4.90 3.20 9.5E+09 1,728

805 0.80 5.2 3.10 3.30 2.10 5.6E+09 1,017

Single family 60 0.46 3.3 0.03 0.07 0.09 2.8E+09 NA

low density 340 0.64 4.7 0.09 0.20 0.27 1.6E+10 NA

200 0.55 4.0 0.06 0.13 0.18 9.3E+09 NA

Single family 97 0.54 4.0 0.05 0.11 0.15 4.5E+09 NA

high density 547 0.76 5.6 0.15 0.33 0.45 2.6E+10 NA

322 0.65 5.8 0.10 0.22 0.30 1.5E+10 NA

Multi-family residential 133 0.59 4.7 0.35 0.17 0.17 6.3E+09 100

755 0.81 6.6 1.05 0.51 0.34 3.6E+10 566

444 0.70 5.6 0.70 0-34 0.51 2.1E+10 333

Forest 26 0.10 1.1 0.01 0.01 0.02 1.2E+09 NA

146 0.13 2.8 0.03 0.03 0.03 6.8E+09 NA

86 0.11 2.0 0.02 0.02 0.03 4.0E+09 NA

Grass 80 0.01 1.2 0.03 0.02 0.02 4.8E+09 NA

588 0.25 7.1 0.10 0.17 0.04 2.7E+10 NA

346 0.13 4.2 0.07 0.10 0.03 1.6E+10 NA

Pasture 103 0.01 1.2 0.004 0.02 0.02 4.8E+09 NA

583 0.25 7.1 0.015 0.17 0.04 2.7E+10 NA

343 0.13 4.2 0.010 0.10 0.03 1.6E+10 NA a For each pollutant and land use, loadings are listed as kg/ha-y (except no./ha-y for FC) in the order minimum,

maximum, median.

NA Not available.

Multiply loadings in kg/ha by 0.89 to get lbs/acre.

TSS total suspended solids

TP total phosphorus

TN total nitrogen

Pb lead

Zn Zinc

Cu Copper

FC fecal coliform bacteria

COD chemical oxygen demand

Source: Horner et al. 1994


Volume IV.B Guidance on Stormwater

Quality Improvement Options for the Snohomish

County Drainage Needs Report

��


Contents 1.0 Evaluation and Discussion of Water Quality Improvement Options.............. 1-1

1.1 Stand-Alone Stormwater Treatment Systems ........................................... 1-1 1.1.1 Pollutant Removal Performance................................................. 1-2 1.1.2 Cost-Effectiveness...................................................................... 1-3 1.1.3 Applicability of Stand-Alone Treatment Systems to Roadways .. 1-5 1.1.4 Discussion .................................................................................. 1-6

1.2 Retrofitted Detention Facilities .................................................................. 1-6 1.2.1 Design Scenarios........................................................................ 1-6 1.2.2 Cost-Effectiveness...................................................................... 1-7

1.3 Roadside Ditches Modified to Function as Biofiltration Swales................. 1-7 1.3.1 Design Scenarios........................................................................ 1-7 1.3.2 Cost-Effectiveness...................................................................... 1-8

1.4 Public Street Sweeping ........................................................................... 1-10 1.4.1 Overview................................................................................... 1-10 1.4.2 Current Snohomish County Practice ........................................ 1-10 1.4.3 Alternative Sweeping Strategies............................................... 1-11 1.4.4 Cost Effectiveness.................................................................... 1-12 1.4.5 Pollutant Load Reduction.......................................................... 1-13

1.5 Catch Basin Sump Cleaning ................................................................... 1-14 1.5.1 Overview................................................................................... 1-14 1.5.2 Current Snohomish County Practice ........................................ 1-14 1.5.3 Alternative Cleaning Strategies ................................................ 1-14 1.5.4 Cost Effectiveness.................................................................... 1-15 1.5.5 Pollutant Load Reduction.......................................................... 1-15

1.6 Porous Pavement.................................................................................... 1-15 1.6.1 Overview................................................................................... 1-15 1.6.2 Open Graded Friction Course in Oregon.................................. 1-16 1.6.3 Recent Studies of Clogging ...................................................... 1-16 1.6.4 Current Snohomish County Practice ........................................ 1-17 1.6.5 Alternative Strategies................................................................ 1-17 1.6.6 Cost–Effectiveness................................................................... 1-17 1.6.7 Pollutant Load Reduction.......................................................... 1-17

1.7 Agricultural BMPs.................................................................................... 1-19 1.8 Septic System BMPs............................................................................... 1-20 1.9 Conclusions............................................................................................. 1-20

2.0 References........................................................................................................... 2-1

3.0 Addendum ........................................................................................................... 3-1

i

Guidance on Stormwater Quality Improvement Options

Tables Table 1. Assumed performance of selected stand-alone BMPs. ........................................1-3 Table 2. Average annual pollutant loadings by land use.....................................................1-3 Table 3. Annualized BMP construction and maintenance cost per pound of TSS

removed. ...............................................................................................................1-4 Table 4. Costs to retrofit existing detention facilities. ..........................................................1-7 Table 5. Costs to retrofit roadside ditches to treatment swales...........................................1-9 Table 6. Estimated pollutant loading reductions for two methods of street sweeping. ......1-13 Table 7. Estimated pollutant loading reductions for two types of porous pavement. ........1-19

Figures Figure 1. Pollutant removal performance of wet basins as a function of storage volume

relative to inflow runoff volume..............................................................................1-5

ii

1.0 Evaluation and Discussion of Water Quality Improvement Options This report documents an evaluation of several types of stormwater quality best management practices (BMPs) for the Snohomish County Drainage Needs Report (DNR) areas. Structural and non-structural BMPs are compared based on cost per pound of pollutants removed, and various implementation issues for those BMP options are discussed. A method for calculating pollutant loading reductions is also provided. The information presented in this report provides guidance for selection of appropriate water quality BMPs for the prevailing conditions in the DNR study areas.

While there are many pollutants of concern, this report uses the reduction of total suspended solids (TSS) as the benchmark parameter. Conversion factors for phosphorus (representing all nutrients) and zinc (representing all metals) are also provided. Eight categories of BMPs are considered:

• Stand-alone stormwater treatment systems

• Retrofitted detention systems

• Roadside ditches modified to function as biofiltration swales

• Public street sweeping

• Catch basin sump cleaning

• Porous pavement

• Agricultural BMPs

• Septic system BMPs.

Most of the discussion in this report focuses on BMPs that could be implemented for water quality improvement in the DNR areas. Failures of existing BMPs should also be evaluated. If existing wet ponds, biofiltration swales, filtration systems, or other stormwater treatment systems are not functioning as intended for pollutant removal, proposed remedies or retrofits should be identified and implemented.

1.1 Stand-Alone Stormwater Treatment Systems A variety of stormwater treatment BMPs are in use in the DNR study areas and elsewhere in western Washington, ranging from small, site-specific facilities to large regional facilities treating runoff from hundreds of acres. The stand-alone stormwater treatment systems that are likely to be recommended in the various DNR study areas will serve larger drainage areas, though solutions could be developed for small, site-specific problems.

Many treatment systems are unsuitable for drainage areas larger than a few acres. Of the conventional, non-proprietary BMPs, these include grass swales and bioretention systems. It is assumed for the purposes of the DNR project analyses that constructed wetlands for stormwater treatment will be given little consideration because of the land requirements, unless

X011084_3538 1.0 Evaluation and Discussion of Water Quality Improvement Options 1-1 December 2002


there is an opportunity to integrate the wetland into a park setting (per communication with Gregg Farris of Snohomish County). Few proprietary products are able to treat the volumes of runoff generated by large drainage areas. The exceptions are CDS and StormFilter devices. The following structural BMPs are considered for applications in the DNR areas:

• Wet ponds

• Wet vaults

• Oil/water separators

• Infiltration basins

• Sand filters

• Sand filters with sorptive media

• CDS

• StormFilter

• Vortechnics

• Drain inlet inserts.

Sand filters and other media filters require a few feet (minimum) of elevation drop between the inlet and outlet, which can constrain their applicability in drainage systems with flat grades. A sorptive media is added to a sand (or other media) filter if a particular water quality situation is deemed sufficiently severe that the dissolved pollutant fraction must be removed, such as phosphorus in the case of a lake and metals in the case of a sensitive stream. Oil/water separators or other oil removal BMPs are likely to be used only at roadway intersections with high traffic volumes. It is also feasible to use small, pre-engineered technologies such as VortechnicsTM at intersections. Drain inlet inserts are believed to be considerably less effective than oil/water separators. However, they may be the only cost-effective approach in some situations, which are discussed below.

Snohomish County currently does not allow wet vaults for treatment of runoff, except for sediment removal, because of insufficient pollutant removal data and a general sense that they most likely perform poorly over the long term (personal communication with Bill Leif of Snohomish County). For cost comparison purposes, wet vaults are included in the analysis below, but they are not recommended for application in the DNR areas.

1.1.1 Pollutant Removal Performance Table 1 lists pollutant removal efficiencies for the selected stand-alone BMPs. Performance of the various BMPs is considered to be highly variable at best and unknown at worst, given the lack of data. Opinions differ in the published literature and results vary in practice. The efficiencies are therefore provided as a guide to facilitate a consistent decision-making process across the DNR areas. Pollutant removal performance of a particular system is a function of two factors: how well the system treats the water that passes through, and the fraction of stormwater that bypasses the system and is therefore not treated. For new developments, design manuals incorporate acceptable bypass rates based on the 6-month storm event. The pollutant removal efficiencies listed in Table 1 apply to large, regional treatment facilities only if the system is sized using the 6-month storm criterion. If space is constrained, it may be reasonable to install a smaller system, but the expected performance will be reduced; this reduction in performance is discussed below.



Table 1. Assumed performance of selected stand-alone BMPs.

BMP

TSS Removal

(%)

Total Phosphorus Removal (%)

Total Zinc Removal (%) References

Wet ponds 80 50 50 Winer (2000), Comings (1998) Wet vaults 80 35 35 No data are known to exist for wet vaults

sized to Washington Department of Ecology criteria; therefore, assume vault performs as well as a similarly sized wet pond except for removal of dissolved fraction.

Oil/water separators

60 20 20 A separator is similar to a wet vault, though is somewhat less effective than a standard wet vault due to smaller size.

Infiltration basins 95 90 90 Hilding (1993), Schueler (1987) Sand filters 90 75 35 Shapiro (1999), Horner and Horner

(1995), Austin (1996) Sand filters with sorptive media

90 75 50 Shapiro (1999)

CDS 60 25 25 Manufacturer’s data

StormFilter 70 50 a 50 b Manufacturer’s data

Drain inlet inserts 25 10 10 a If iron-infused media is used. b If leaf compost or zeolite is used.

The assumed efficiencies are used to calculate pollutant loading reductions, which form the basis of a cost-effectiveness evaluation. Average annual pollutant loadings used in this analysis are listed in Table 2 (Horner et al., 1994).

Table 2. Average annual pollutant loadings by land use. Land Use TSS Total Phosphorus Total Zinc

Low density residential 60 0.45 0.07

Medium density residential 130 0.55 0.11

High density residential 200 0.60 0.17

Commercial 300 0.70 1.70

Industrial 300 0.70 3.40

Road 250 0.60 0.18

Note: Loading data presented in lb/acre/year.

Source: Adapted from Table 2.6 of Horner et al. (1994).

1.1.2 Cost-Effectiveness Cost data for 46 individual stormwater treatment systems were obtained from the consultants participating in the Snohomish County DNR project. The following information was gathered for each of these systems: construction cost, the type of land use, the drainage acreage, the year of the cost figure, and whether the cost is an estimate or actual contractor bid. Construction



costs only were provided, and do not include the cost of land or costs for engineering design and permitting. Combination treatment BMPs, and BMPs integrated with a detention system, were excluded from the analysis. Although grass swales are inappropriate as regional treatment facilities, they are included for comparison purposes, as are vortex separators. Cost data for drain inlet inserts were not provided by consultants participating in the DNR project. For this type of technology, manufacturers’ cost information was used for two products, the Abtech Ultra Urban FilterTM and the HydroKleenTM.

A summary of construction and treatment costs by technology is provided in Table 3. A complete analysis of costs by individual project is attached (see Addendum). Treatment systems with cost figures prior to 2002 were updated to the year 2002 assuming an inflation rate of 3 percent per year. The construction costs were annualized using a facility life of 20 years and a discount rate of 3 percent. The maintenance costs were derived from King County (1995), and were similarly updated. King County (1995) concluded that the maintenance cost for each type of technology is essentially the same regardless of facility size, which is a valid conclusion for comparatively small onsite systems where the size range between systems is not dramatic. However, the maintenance costs for large, regional facilities are greater; therefore, the maintenance costs incorporated in Table 3 are not representative of the costs of larger systems.

As noted above, the costs in Table 3 do not include engineering, permitting, or land costs. Both new and retrofit projects are included; the data suggest there is no significant difference between the two types of projects. The average annual TSS loadings listed in Table 2 were used to calculate cost per pound of TSS removed. The cost per pound of TSS removed is very sensitive to the assumed TSS loadings (Table 2) and TSS removal efficiencies (Table 1). For example, if the loading values in Table 2 were doubled, the annual cost per pound of TSS removed would be halved. To ensure a consistent analysis, the same TSS loadings must be used throughout the comparison of BMPs.

Table 3. Annualized BMP construction and maintenance cost per pound of TSS removed.

BMP Number of Projects

Cost Range ($/lb TSS Removed)

Average Cost ($/lb TSS Removed)

Median Cost ($/lb TSS Removed)

Wet pond 5 $2.04 - $14.96 $6.99 $4.33 Wet vault 7 $4.30 - $61.32 $22.03 $10.25 Oil/water separator 6 $2.81 - $24.12 $10.37 $5.92 Sand filter 3 $4.04 - $26.05 $14.35 $12.96 Grass swale 5 $0.50 - $4.38 $1.49 $0.92 StormFilterTM 1 $7.79 $7.79 $7.79 Vortex separator 1 $4.44 $4.44 $4.44

Two projects not included in Table 3 illustrate the potential escalation in unit costs for small sites. Projects 33 and 34 listed in the addendum are for very small sites of less than one acre. The unit costs are $62 and $22 per pound of TSS removed, respectively. The higher unit costs should not be attributed to the treatment system, which is a StormFilterTM, but to the small area of the catchment. The unit costs of all other treatment technologies would also increase correspondingly if they were used to treat very small areas that generate minor pollutant loadings.



Space constraints may not allow the installation of facilities that meet the Washington State Department of Ecology (Ecology) criterion of treating the runoff from the 6-month storm event. This is most likely to occur with wet basins and sand filters. Figure 1 illustrates the estimated performance of wet basins (USEPA 1986). The performance relationship is based on the ratio of the volume of the wet pool (Vb) to the volume of the runoff (Vr) of the mean annual storm (0.5 inches times the impervious surface area less 0.05 inches abstraction). A wet basin sized to the Ecology requirements has a Vb/Vr ratio of about 3, and will likely achieve 80 percent removal of TSS. The Vb/Vr ratio was calculated for each site, and Figure 1 can be used to estimate wet basin performance.

Figure 1. Pollutant removal performance of wet basins as a function of storage volume relative to inflow runoff volume.

0%

20%

40%

60%

80%

100%

TSS

rem

oval

effi

cien

cy

0 1 2 3 4 5 6 Volume of wet pool/volume of runoff

The effect of reduced size for sand filters differs compared to the effect for wet basins. Sand filters remove the same amount of pollutants from stormwater that passes through the filter as wet ponds. However, the amount of water treated over time decreases with a smaller filter. A simulation program such as the King County Runoff Time Series (KCRTS) model can be used to determine the effect of a smaller filter. To assess the pollutant removal effectiveness of a relatively small sand filter, the sand filter is sized assuming that sufficient space is available to meet the criterion of treating 90 percent of the stormwater over time. The actual volume treated for the space-constrained situation is then calculated. The ratio of the two treated stormwater volumes, multiplied by the assumed pollutant removal performance in Table 1, represents the reduced pollutant removal capability.

1.1.3 Applicability of Stand-Alone Treatment Systems to Roadways Roadways are likely to be target areas for installation of treatment systems in the DNR study areas. Field studies indicate higher pollutant loadings in runoff from roadway intersections than from the roadways between the intersections (Drapper et al. 2000). Intersections with combined average daily traffic (ADT) in excess of 30,000 vehicles should be considered candidates for installation of treatment systems that target oil removal. Above this ADT level, concentrations of pollutants become significant (Driscoll et al. 1990). The assumption is that petroleum



hydrocarbons are the major pollutant of concern at roadway intersections. However, TSS and metals concentrations are also elevated at intersections at levels considerably higher than for residential and most commercial development. Therefore, the most appropriate treatment solution is either a filter that effectively removes oil, an oil/water separator (with coalescing plates), or drain inlet inserts. In situations where all drainage from the intersection accumulates at one point prior to movement away from the intersection, the most cost-effective solution is likely a filtration system or an oil/water separator. Although the construction cost is considerably higher for these systems than for drain inlet inserts, the long-term life cycle cost is likely lower, based on the cost per pound of pollutant removed. However, it should not be presumed that this is the case and the life cycle cost of filters or separators versus drain inlet inserts should be evaluated. If not all of the water drains to one point, the cost of two or more filtration systems or oil/water separators, or of the modification of the drainage system to allow the use of only one treatment system, is likely prohibitive. In this case, drain inlet inserts are a reasonable alternative.

There are many drain inlet inserts on the market. Although there is little performance and maintenance information available, some products are considered preferable and likely to give better performance based on their design. Inserts that should not be used are those that allow for easy bypass of stormwater, e.g., tray devices. Only those inserts configured as boxes that force the water to pass through the sorptive media are appropriate. Products that fit this criterion are the HydroKleenTM and the UltraUrban FilterTM by Abtech Industries. Box inserts are also easy to maintain. Sediments are removed by vactor truck directly from the box. The sock configuration by Foss Industries and others has a much lower initial cost but is difficult to maintain. Furthermore, the sorptive pillow provides no added benefit while adding considerably to the cost (Hrachovec and Minton 2001).

1.1.4 Discussion The small number of projects used to develop the data for each BMP in Table 3 makes it difficult to reach definitive conclusions. However, the data suggest some general conclusions. Grass swales are the least expensive BMP. Wet vaults are more expensive than wet ponds. However, with the land considered, the cost of wet ponds and wet vaults may be similar. The costs for sand filters listed in Table 1 are skewed by the inclusion of one underground facility in the study. If this facility is excluded, sand filter costs are competitive with wet ponds. With the inclusion of all costs including land, and certainly the opportunity cost of land in urban areas, there is likely little difference in the unit cost between wet ponds, wet vaults, and sand filters in commercial developments. However, the cost-effectiveness of sand filters depends significantly upon the available elevation differential from inlet to outlet.

1.2 Retrofitted Detention Facilities

1.2.1 Design Scenarios There are numerous stormwater detention facilities in the DNR study areas. Many of these facilities were not designed to provide a water quality treatment function, and many others were designed to provide water quality treatment according to outdated standards (i.e., the treatment pool is very small and/or shallow in relation to the volume of runoff to be treated). Depending on the layout of the individual detention pond site, there may be available space to readily expand the footprint or pond depth to create a larger water quality pool in the bottom of the facility, beneath the detention storage volume.



1.2.2 Cost-Effectiveness Snohomish County Surface Water Management (SWM) has an experimental program to retrofit existing stormwater detention facilities to provide water quality benefits. Four sites have been evaluated, all in medium density residential settings, with drainage areas from 55 to 173 acres. Estimated construction costs range from $32,000 to $164,000. The estimated construction costs were annualized using the same assumptions as for new treatment facilities as described above.

The efficiency of each facility depends on the volume of the retrofitted wet pool in relation to the mean annual storm runoff volume (USEPA 1986). This relationship is shown in Figure 1. TSS removal efficiencies for the four ponds evaluated by Snohomish County SWM are estimated to range from 10 to 35 percent. The annual cost per pound of TSS removed ranges from $2.09 to $7.06. This analysis is presented in Table 4. These are construction costs and should be adjusted by 130 to 150 percent to account for engineering and permitting costs. There is no land cost, as the land has already been committed for stormwater control at each site. The analysis indicates retrofitting is cost-effective relative to the cost of new treatment facilities, as some of the cost components were incurred with the original detention facility, such as maintenance access driveways. The analysis indicates it is worthwhile to retrofit existing detention facilities for enhanced pollutant removal where the drainage area is of considerable size.

1.3 Roadside Ditches Modified to Function as Biofiltration Swales The potential for existing roadside ditches to improve stormwater quality has been previously evaluated (Colwell et al. 1999; Minton 1993). Colwell et al. (1999) found that the majority of ditches were of the desired shape and well vegetated, and provide recommendations on how to enhance the capability of existing and new ditches. A handbook provides a methodology for evaluating the capabilities of swales (Minton, 1993). Both reports contain further information of interest to analysts working on the DNR project.

Table 4. Costs to retrofit existing detention facilities.

Project Drainage

Area

Estimated Construction

Cost TSS Removal Efficiency (%)

$/lb TSS Removed

1 55 $32,960 18 $5.32 2 173 $168,920 35 $2.09 3 79 $52,530 10 $7.06 4 85 $83,739 15 $5.86

1.3.1 Design Scenarios There are three alternative configurations to create fully effective biofiltration swales from roadside drainage ditches. Each involves an unpaved shoulder beside the immediate paved shoulder. The first configuration is to widen and flatten the bottom of the ditch to the extent practicable within available right-of-way so it resembles a standard bioswale. (If additional right-of-way would need to be acquired to accomplish an effective ditch retrofit, then pursuing such a capital improvement project may prove too costly for the modest pollutant removal gains.) The



limitation of this configuration is that with water entering laterally along the length of the ditch, there is a point where the water volume is sufficient to submerge the grass, violating the design requirement of erect grass. The allowable length of the ditch depends upon the width of the ditch bottom, the slope of the ditch, and the volume of runoff per lineal foot of roadway, and therefore road width. Should the length of a particular ditch section exceed the criterion, the pollutant loading reduction is based only on the allowable length. It is assumed that the rest of the ditch downstream of this point does not effectively treat runoff. If, for the particular roadside condition, the maximum length of bioswale allowed without violating the performance requirements is 250 feet, but the length of the ditch is 1,000 feet, only treatment by the first 250 feet is counted.

The limitation of the first configuration is solved in the second configuration. Where the length of the ditch is too long, catch basins are installed at the intervals with a subsurface conveyance pipe. If, for the particular roadside condition, the maximum length of bioswale allowed without violating the performance requirements is 250 feet, but the length of the ditch is 1,000 feet, catch basins are located at intervals of 250 feet to capture all runoff treated in the upstream segment of the swale. In the first study to evaluate this concept (Minton 1993), a general criterion was identified for modifying ditches in existing roads: 500 feet of bioswale if one lane plus shoulder drains to the ditch, and 250 feet of bioswale if the entire (two lane) road drains to the ditch, assuming a ditch bottom width of 2 feet and a slope less than 6 percent.

The third configuration is the ecology ditch, developed by the Washington State Department of Transportation (David Evans & Associates 1994). Permeable material consisting of perlite, dolomite lime, and gypsum is placed in the ditch over a perforated pipe. This media treats the stormwater as it infiltrates down to the perforated pipe. The maximum allowable length of ditch that can effectively treat the incoming runoff is based on the capacity of the underdrain pipe. The maximum longitudinal slope that still enables vertical filtration of the runoff volume is not known.

Another scenario likely to be found at many sites in the DNR study areas is a roadside ditch with insufficient length to meet the typical design length criteria for a bioswale. While these ditches may not be able to fully treat the tributary runoff to a degree that a full-length bioswale would, they should nonetheless be considered for retrofitting to create short bioswales because of the low cost.

1.3.2 Cost-Effectiveness An evaluation of the cost to retrofit roadside ditches for configurations 1 and 3 is presented below. The cost examples are based on a roadway width of four standard lanes plus minor shoulders, with a total paved width of 55 feet. They include a ditch with a 2-foot bottom width, 2-foot depth, 0.5H:1V side slopes, a longitudinal slope of 3 percent, and an available swale corridor width of 15 feet off the edge of the road. Ecology bioswale sizing criteria (Ecology 2001) are applied to the first configuration (Ecology 2001).

For the first configuration, an evaluation of the maximum roadway drainage area that can be served by a single bioswale and a cost estimate for the bioswale retrofit are provided below. The site drainage area is about 2 acres, and it is assumed that a 2-foot-deep ditch is modified to create a swale with a 3-foot-wide bottom and 3H:1V side slopes (i.e., to fit it into a 15-foot width in the right-of-way).

For the second configuration, where the roadway drainage area can expand and the design is modified accordingly with successive catch basins, a cost estimate is not provided. It is difficult to accurately assess the likely cost of this type of swale retrofit because local drainage



characteristics dictate how much or how little storm drain pipe would need to be connected to the catch basins to discharge the corresponding flow. The cost of storm drain trenching directly affects the retrofit cost. This variable raises the cost per pound of TSS removed in comparison to the first configuration.

A cost estimate is provided for the ecology ditch (configuration 3) assuming that 2,000 feet of ditch is retrofitted with perforated pipe and filter media. It is assumed that the 2-foot ditch bottom is widened to 3 feet and that the ecology ditch has 1H:1V side slopes, rather than the 3H:1V assumed for the first configuration.

Table 5 lists the analysis results, including the pollutant removal benefits. It is assumed that the TSS removal efficiency for the first configuration, a conventional bioswale, is 80 percent, and that the TSS removal efficiency of the ecology ditch (configuration 3) is similar to a sand filter, or 90 percent (Table 1). Costs are annualized using the same assumptions as in Table 3. The costs in Table 5 are estimated construction costs, and should be adjusted to account for engineering and permitting costs. There is no land cost assumed in these figures, as it assumed that these retrofits are considered only where available space exists in the roadway right-of-way for the ditch expansion.

Table 5. Costs to retrofit roadside ditches to treatment swales. Ditch

Configuration Drainage Area

(acres) TSS Removal Efficiency (%)

Construction Cost

$/lb TSS removed

1 2.0 80 $22,000 $5.55 3 2.5 90 $176,000 $28.40

If a ditch is retrofitted with a relatively short bioswale, the cost-effectiveness is approximated based on the size of the swale treatment area relative to the size that is required to fully treat the tributary runoff in the 6-month design flow event (as stipulated by Ecology [2001]). For example, if runoff from a 1-acre roadway drainage area enters the ditch at present, and the resultant bioswale retrofit is only half the length of that required to fully treat the 6-month design flow, then the pollutant removal effectiveness is approximated as half of that shown in Table 5. This is a reasonable approximation given that flow residence time is considered a key factor in the pollutant removal effectiveness, assuming all other design factors (such as grass health and sheet flow conditions) are equal.

The tributary drainage area is used to develop a rough estimate of cost-effectiveness. The pollutant loading from that area can be estimated using the data presented in Table 2. It should be assumed that cost-effectiveness significantly drops if extensive storm drain or culvert reconfiguration would be needed. For instance, it is not likely to prove cost-effective to redirect runoff from one side of a road to the other in order for that runoff to enter the retrofitted bioswale. The cost of pipe trenching across the roadway is typically too great for the modest pollutant removal benefits that are achieved. This is considered a general guideline rather than an absolute rule.

It is assumed that bioswale retrofits for ditches are more beneficial in areas of high traffic, such as arterial roads and major intersections, although this cannot be quantified in the context of the simple cost-effectiveness methodology outlined above. This assumption is based on the greater loadings of pollutants such as TSS, zinc, copper, and petroleum products that are likely to occur in these areas compared to minor roads carrying low traffic volumes.



1.4 Public Street Sweeping

1.4.1 Overview Several studies have measured the effectiveness of street sweeping in reducing end-of-pipe runoff pollution concentrations and loads. Sartor and Boyd (1972) found that sweeping on a seven day cycle is ineffective, while daily sweeping was shown to remove larger-sized pollutants typical of street surface material (Sartor and Gaboury 1984). Pitt and Shawley (1982) and Bannerman et al. (1983) concluded that street sweeping provided only minor pollutant removal benefits. The conclusion of the U.S. Environmental Protection Agency Nationwide Urban Runoff Program (NURP) is that street sweeping is not effective at reducing end-of-pipe pollutant loads (USEPA 1983).

However, the above studies were of the mechanical or brush sweepers. There have since been significant advances in both sweeping technology and techniques. Two different types of sweepers made available since the completion of the above studies are the regenerative air sweeper and the vacuum/high-efficiency sweeper. Mechanical sweepers are ineffective at removing particles less than about 100 to 200 microns (Sartor and Boyd, 1972), while the new sweepers are much more efficient at collecting these particles. Sweeping techniques have also changed. A technique first evaluated in Portland, Oregon (Sutherland and Jelen 1996) is to immediately follow a brush sweeper with a regenerative air sweeper. This method cost-effectively increases overall pollutant removal efficiency. Furthermore, newer mechanical sweepers are generally more efficient than those that existed in the 1970s (Sutherland personal communication, Woodward-Clyde 1994). Alter (1995) and Sutherland and Jelen (1996, 1997) assert that the overall conclusion of the NURP studies is now obsolete. Their investigations show that stormwater runoff quality benefits are cost-effective when better sweepers and optimal sweeping frequencies are employed. Such a strategy maximizes the removal of the fine sediments. The removal efficiencies of mechanical, regenerative-air, and vacuum/high-efficiency sweeping are roughly 10 percent, 50 percent, and 80 percent (respectively) of the pollutants that would otherwise be found in the stormwater (Sutherland personal communication). The estimate of 10 percent for mechanical sweepers applies only to models made available in the last 15 years.

1.4.2 Current Snohomish County Practice Snohomish County crews currently sweep public streets. The County seeks to determine if it would be cost effective to increase sweeping frequency using the higher efficiency equipment, relative to structural treatment systems. The Public Works Department has provided the following information on the current level of activity and costs:

• The approximate annual budget for street sweeping is $500,000, which includes equipment amortization.

• Approximately 4,000 curb-miles are swept annually, at an average cost of $125 per curb-mile.

• The County has about 3,200 total curb-miles of streets.

• The distribution of the curb-miles between commercial, industrial, and residential land uses is unknown.

• Sweeping frequency is about once per year for residential areas but more frequent for commercial areas, with an overall average of about 1.25 times per year per curb-mile.



• A total of about 2,700 cubic yards (72,900 cubic feet) of sediment is removed per year by all sweepers, or approximately 0.675 cubic yards per curb-mile.

• Sweeping is done with four mechanical sweepers.

Using a sediment weight of 100 pounds per cubic foot (Sutherland personal communication), the data indicate that the County’s street sweeping practices cost approximately $0.07 per pound of sediment and debris removed. This cost figure is misleading as most of what sweepers remove from the street is not related to stormwater quality because of its large size (greater than 2,000 microns, or 2 mm in diameter). Larger material is either not washed from the street, or if washed off during rare extreme events, it is captured by catch basins or other components of the drainage system. Only 15 to 20 percent of the material in street sediment is retained in stormwater, eventually reaching the receiving water (Pitt and Bissonette, 1984). Further, mechanical sweepers are very inefficient with the removal of small particles. Given these factors, the cost per pound of TSS removed from the stormwater under current County practice is probably approximately $2.00 to $4.00. While this appears to be less costly than structural BMPs (Tables 3 and 4), little water quality benefit accrues because mechanical sweeping pollutant removal efficiency is only 10 percent.

1.4.3 Alternative Sweeping Strategies The options for increasing pollutant removal from streets are to sweep more frequently and/or to use equipment that efficiently collects the smaller particles. If very low efficiency brush sweepers are used, a significant loading reduction is achieved only if regenerative-air and/or vacuum high-efficiency sweepers are used in tandem.

If commercial streets are to be swept frequently, parking controls may be necessary. If sweeping is to occur during the day, it may be necessary to impose parking restrictions. A common approach is to specify with street signage that the street to be swept must be clear of vehicles during specified hours on a particular day of the week or month. The public is notified initially of the program through educational efforts. The cost of such a program must be included in the overall cost of sweeping. Alternatively, sweeping can occur between 12:00 a.m. and 6:00 a.m., with the expectation that some cars will be in the parking lane. Under this approach, the costs presented in this report would likely increase to reflect greater time spent sweeping per curb-mile as a result of avoiding cars parked in the curb lane. If residential streets are swept on a monthly or quarterly basis, temporary relocation of vehicles may not be necessary because many residential streets are typically free of parked vehicles during the day.

One alternative sweeping strategy is to focus on the intersections with traffic volume in excess of 30,000 vehicles per day. As noted previously, concentrations of pollutants are significantly higher in these areas. The second alternative strategy is to sweep less frequently in the winter and more frequently in the summer, particularly August through October. The rationale for a seasonal modification in sweeping frequency is the seasonal variation in effects on receiving water. During the summer, stream flows are low and fish metabolism is at its highest due to elevated water temperatures. The impact of stormwater is likely to be greatest during this period. Increasing sweeping frequency from biweekly to weekly in commercial areas reduces the likelihood of heavy loading to the stream when fish are most vulnerable. To accomplish this within the same budget, the sweeping frequency is reduced during the winter in commercial areas, from biweekly to monthly. During the winter the opposite environmental condition exists; stream flows are higher and fish metabolism is lower. The same stormwater pollutant loading may occur, but concentrations and biological effects are less and therefore likely to be acceptable.



A further option for the County to consider is to require that owners of private parking lots sweep, particularly the highly active retail parking lots. It is likely that owners of many of these properties are already sweeping. In these cases, the type of sweeper used and the frequency of sweeping are important. The County could specify that vacuum sweepers be used.

1.4.4 Cost Effectiveness Recent studies provide information on the cost effectiveness of newer sweepers, equipment, and optimal sweeping frequencies. These analyses have concluded that regardless of the type of sweeper, cost effectiveness drops significantly when the marginal (not average) cost approaches $10 per pound of TSS removed (HRC 2001). This threshold is the same irrespective of the type of sweeper. However, the total amount of material removed varies with the type of sweeper. Generally, optimum sweeping based on cost effectiveness is weekly to monthly in commercial and industrial areas, and monthly to quarterly in residential areas (HRC 2001). If swept more frequently, the marginal cost increases dramatically. This frequency is less than what is believed to be optimal for water quality benefits, which is once or twice per week during the wet season and monthly to bimonthly during the dry season, given the climate of western Washington.

In a direct comparison between wet vaults and sweeping with vacuum/high-efficiency sweepers, the life-cycle cost of sweeping was about 20 percent of the wet vaults (Sutherland et al. 1995). Another study compared the cost of installing and maintaining a subsurface structural facility in a large development to the cost of sweeping parking lots and city streets (Blosser 2000). If the data from that study are analyzed according to the methods discussed in this report, the unit cost of the structural facility from that study is about $8.25 per pound of TSS removed per year excluding engineering and permitting costs. The unit cost for street sweeping is estimated at $0.80 per pound of TSS removed per year. The sweeping cost includes equipment amortization. The high efficiency EnviroWhirlTM (EV) sweeper was evaluated independently by a watershed district (LBWID 1998). The cost per pound of street dirt removed (not pound of pollutant reduction) was $0.07 at a sweeping cost of $55 per curb-mile. Recent studies (HRC 2001, Tetra Tech 2001) indicate that while the initial cost of the EV sweeper may be higher than regenerative air sweepers, the cost per pound of sediment removed is lower with the EV because of its higher efficiency. The unit cost for the EV sweeper ranges from $0.60 to $3.75 per pound of TSS removed depending on the land use and the sweeping frequency. Sweeping residential areas is more expensive ($1.40 to $3.75 per pound of TSS removed) than commercial areas ($0.60 to $2.00 per pound of TSS removed). These unit cost ranges are for sweeping frequencies of once per month (higher unit cost) or once per two months (lower unit cost). All of the sweeping costs cited above do not include the cost of parking controls. These unit costs are of the TSS prevented from entering stormwater, not of the total loading of sediment removed from the pavement.

Using the EV sweeper is particularly expensive. However, a life cycle cost analysis will likely show that it is no more expensive than a mechanical or regenerative-air sweeper for two reasons. First, an EV sweeper does not use water. Also, experience suggests that an EV sweeper has less down time due to mechanical problems (Sutherland personal communication; LBWID, 1998), perhaps in part because it sweeps dry. The increased amount of time that the EV sweeper is on the street equalizes the costs of the various other types of sweepers when considered on an hourly basis. A potential constraint in the use of the EV is that its road speed is limited to about 25 miles per hour. Nonetheless, for an urban county this may not be a limitation if sweepers are located at different county maintenance yards and do not have to travel long distances to sweeping sites. Tennant Company has recently introduced a



CenturionTM sweeper that is mounted on a truck chassis. Tennant claims that this is a high-efficiency sweeper but as yet there are no pollutant removal performance data available.

1.4.5 Pollutant Load Reduction While sweeping streets may cost only 10 to 25 percent of the cost of structural treatment BMPs, the question remains as to what pollutant loading reductions are achieved given that public streets represent only a portion of the drainage basin acreage whereas a structural BMP treats stormwater from the entire catchment that it serves. One study evaluated the relative contribution of various components of the urban landscape (e.g., streets, lawns, roofs) to pollutant loadings in runoff (Bannerman 1993). Streets typically represent 10 to 15 percent of the catchment area. The volume of runoff as a percentage of the total catchment runoff volume was about 10, 30, and 60 percent for industrial, commercial, and residential areas, respectively. The respective percentages of pollutant loadings from the streets were as follows for the industrial, commercial, and residential areas:

• TSS loadings were about 25, 70, and 80 percent.

• Total phosphorus loadings were about 20, 55, and 60 percent.

• Total zinc loadings were about 10, 45, and 80 percent.

The paucity of data requires that these percentages be considered with caution. Reductions in pollutant loading by street sweeping have been calculated and the results are shown in Table 6. The calculations assume that regenerative-air and high-efficiency sweeping are 50 percent and 80 percent efficient, respectively, and optimal sweeping frequency is also assumed. The loading values listed in Table 2 (used to generate Tables 3 and 4) are used in the analysis. Not all residential areas are curbed, and only areas that are curbed should be included in an analysis of sweeping potential for an individual watershed. This is because TSS loads entrained in runoff in uncurbed areas are not retained on the road shoulder for easy removal. As it is assumed that streets in low-density residential areas in Snohomish County are generally not curbed, this land use is not included in Table 6.

Table 6. Estimated pollutant loading reductions for two methods of street sweeping.

TSS Total Phosphorus Total Zinc

Land Use

Regenerative-Air

(Lb/acre/ year)

High-Frequency (Lb/acre/

year)

Regenerative-Air

(Lb/acre/ year)

High-Frequency (Lb/acre/

year)

Regenerative-Air

(Lb/acre/ year)

High-Frequency(Lb/acre/

year)

Medium density residential

52 83 0.17 0.26 0.04 0.07

High density residential

75 120 0.18 0.29 0.06 0.11

Commercial 105 168 0.19 0.31 0.38 0.61

Industrial 38 60 0.07 0.11 0.17 0.27

For the purposes of this analysis it is assumed that the County currently sweeps all curbed commercial areas bimonthly, and all curbed residential areas once per year. Table 6 assumes the future condition is that commercial areas are swept biweekly and residential areas are swept



monthly. This would be an aggressive approach, but the loading reductions listed in Table 6 are likely low if that aggressive approach were indeed implemented. If a less aggressive sweeping schedule is adopted and commercial areas are swept monthly and residential areas bimonthly, the TSS loading reductions listed in Table 6 should be decreased by 40 percent for planning estimates.

1.5 Catch Basin Sump Cleaning

1.5.1 Overview The value and cost benefits of cleaning catch basin sumps are dependent on four factors: the size of the sumps, cleaning frequency, the sediment loading, and street/parking lot sweeping practices. The general recommendation to maximize the pollutant trapping efficiency of the catch basin is to clean at least annually (Pitt and Bissonette 1984), or when the sump is 60 percent full (Pitt and Bissonette 1984, Ecology 2001). However, this recommendation is based on catch basins with shallow sumps about 12 inches deep. Catch basins with deeper sumps need not be cleaned as frequently. If aggressive sweeping is occurring on the associated parking lot or street, the frequency of cleaning catch basins can be reduced accordingly.

Catch basins collect primarily coarse material; this is of little benefit to stormwater quality (Pitt and Bissonette 1984, HRC 2001). The few studies available on this subject (Pitt and Shawley 1982, HRC 2001) suggest that cleaning catch basin sumps has a modest effect on water quality, generally less than 5 percent TSS removal. However, cleaning sumps may be more politically acceptable than aggressive street sweeping if parking control is needed.

1.5.2 Current Snohomish County Practice Snohomish County currently cleans catch basins. The County seeks to determine if it would be cost effective to increase the intensity of catch basin cleaning, relative to structural treatment systems. The Public Works Department has provided the following information on current level of activity and costs:

• An approximate annual budget of $300,000 is allocated to catch basin cleaning, and includes equipment amortization.

• 3,000 catch basins are cleaned annually.

• The distribution of the catch basins that are cleaned between commercial, industrial, and residential land use areas is unknown.

• The depth distribution of sumps is unknown.

• About 1,500 tons of material was removed from cleaned catch basins in 2000, or about 0.5 tons (6.5 cubic feet) per catch basin; this quantity is misleading as it also includes the cleaning of culverts.

• The County has about 40,000 catch basins in its jurisdiction.

• Each catch basin is cleaned on average about once per 12 years.

1.5.3 Alternative Cleaning Strategies There are two alternatives to cleaning sumps more frequently. The first alternative, cleaning sumps more frequently than the current rate, gradually increases the unit cost per pound of TSS



removed because the sumps that are cleaned more frequently contain less material. If it is assumed that cleaning occurs annually, it is reasonable to expect that the amount of material removed per cleaning would be less, perhaps half as much than is removed on the current County schedule, depending on sump depth. As a result, cleaning more often than once per year is not cost-effective (Woodward Clyde, 1994a). A second alternative is discussed in a recent study (HRC, 2001), which recommends cleaning catch basins once per 2.5 years. This recommendation is made in part because of the relatively high unit cost per cleaning and the uncertain effects of enhanced street sweeping on sediment accumulations in the sumps. Generally, the unit cost of sweeping is less than cleaning sumps (HRC, 2001), particularly if the sump depths are moderate (such as 2 feet). The unit cost of catch basin cleaning in Snohomish County is currently relatively low because the sumps are cleaned infrequently and typically are full.

1.5.4 Cost Effectiveness Based on the above data, the costs per catch basin cleaning and per pound of sediment removed are about $100 and $0.10, respectively. As previously stated, these costs are misleading because catch basins tend to remove coarse sediment of little consequence to stormwater quality. Most of the material found in catch basins that is less than 500 microns in diameter is retained in the stormwater. However, catch basins do slightly improve stormwater quality. If it is assumed that only 5 percent of the sediment in a sump is of consequence to water quality, the cost of pollutant-related TSS removal is about $2.00 per pound.

1.5.5 Pollutant Load Reduction For planning purposes it is suggested that the cleaning frequency for catch basin sumps with depths of one foot, two feet, and three feet should be once per year, once every two years, and once every three years, respectively. Cleaning at this frequency could provide a benefit of about 5 percent TSS loading reduction annually.

1.6 Porous Pavement The following discussion relates to contiguous pavement, not open paving blocks or paving stones. There are three alternative paving configurations:

1. The entire pavement structure, including imported base material, is porous; the parent soil is able to infiltrate the entire runoff volume of the specified design event.

2. The entire pavement structure, including imported base material, is porous; an underdrain system is included because the parent soil is incapable of infiltrating the runoff volume of the specified design event.

3. Only the final lift (e.g., the final layer of pavement laid in a sequential series of vertical layers) of pavement is porous, with standard pavement beneath; water drains laterally along the interface of the porous and non-porous pavement layers to the edge of the road.

1.6.1 Overview Stormwater management engineers in the United States have a generally negative opinion of porous pavement. The perception is that porous pavement is prone to failure and should not be used (Lindsey et al. 1991, Galli 1992). If it is used, then it should be located only in low traffic areas (Young et al., for FHWA 1996, USEPA 1999). A recent summary report by the Federal



Highway Administration (Shoemaker et al. 2000) supports the long-held view in the United States that porous pavement should be limited to low-traffic areas. This view stems from the studies of the early 1980s (that were incorporated in the publications listed above) that found a significant number of failures. There are a few states and several European countries with an alternate view. In these geographic areas porous pavement is considered by many to be highly preferable, particularly in high traffic or high speed areas (Camomilla et al. 1990, Heystraten and Moraux 1990, Isenring et al. 1990). Its use in the areas studied is not related to water quality, but for skid and noise reduction; therefore, porous pavement is used in high traffic or high speed areas where these benefits are fully achieved. It is also believed that in high speed areas there is less tendency for the porous pavement to clog as the turbulence of the traffic blows particulates to the side of the road, reducing the potential for clogging. Porous pavement is used in Europe in light traffic areas as well (Balades et al. 1995). It is likely that failures in the U.S. in the 1970s and 1980s were due to poor construction practices, parent soils with inadequate infiltration capacity, and/or the lack of maintenance (i.e., sweeping), rather than due to a fundamental flaw in the concept of porous pavement.

1.6.2 Open Graded Friction Course in Oregon Configuration 3 (from the list above) has been a common practice of the Oregon Department of Transportation (ODOT) for over 30 years. ODOT uses the term “open graded friction course” (OGFC) to describe configuration 3 (Moore, personal communication). The OGFC surface lift of porous pavement is about 2 inches thick. As of 1994, ODOT had about 1,800 miles of OGFC (Younger et al. 1994), but now has considerably more (Moore, personal communication). Water drains laterally to the side of the road rather than vertically downward. The water drains through the porous shoulder and into the soil on the edge of the roadway (Moore, personal communication). This configuration can also be used on existing roads. When the top layer of pavement has deteriorated to the point of needing replacement, it is replaced with OGFC.

A report written for ODOT (Younger et al. 1994) summarized the findings of previous engineering studies on the advantages of porous pavement: improved skid resistance, decreased splash and spray, noise reduction, reduced hydroplaning, reduced rutting potential, and reduced glare. That report stressed that these advantages, in particular reduced rutting potential, are highly dependent upon the particular asphalt mix. The study included field and laboratory research that confirmed the advantages noted above. Potential disadvantages cited include: construction difficulties, potential for clogging, oxidation of the pavement binder, difficulty of making small batches for patching, and winter performance issues. Winter performance concerns are loss of deicing material into the pores of the asphalt, snow plow damage, and deicing sand clogging the pores. The report recommended that porous pavement not be used in mountainous areas. The report also stated that porous pavement should not be used in city streets or in areas that require a lot of construction handwork, but did not provide an explanation for this conclusion. It is likely that cost is the concern. The unit cost of using porous pavement on city streets is likely more expensive than highways because the greater amount of hand work required to pave city streets.

1.6.3 Recent Studies of Clogging Most studies have found that it takes a few years before significant clogging occurs in porous pavements. The Federal Highway Administration (Young et al. 1996) made the following conclusions: “limited data … (indicate clogging in) 5 to 10 years” for “low traffic areas.” The Arizona Department of Transportation evaluated a 3,500-foot test section of porous pavement (Hossian et al. 1991). The average daily traffic (ADT) volume in the test area was about 30,000



vehicles. After five years they concluded that “...although a slight decrease in the infiltration rate has occurred, both the infiltration rate and the storage capacity are above the design values” (Hossian et al. 1991). In that test, the entire cross-section of the pavement was porous (though it included a subsurface drainage trench), not just the final (top) layer. The report does not indicate whether the test area was swept.

A study of pavements in parking lots and residential streets found essentially no clogging in the first year of operation and about a 50 percent reduction of infiltration capacity after two years (Balades et al. 1995). Alternative maintenance methods to restore infiltration capacity were also studied. Simple (most likely mechanical brush) sweeping provided no benefit, while two passes with a vacuum sweeper or a pressure water jet restored the infiltration capacity. The authors cite another study of infiltration reduction in the first year at multiple sites: 30 to 50 percent in rural areas, 40 to 70 percent in cities, and 60 to 90 percent in very polluted areas. Another study of a highway found the porous pavement to be essentially clogged after three years (Stolz and Krauth, 1994).

1.6.4 Current Snohomish County Practice Porous pavement is currently not encouraged or required for public streets or private parking lots in Snohomish County.

1.6.5 Alternative Strategies There are four programmatic options that could be considered in the DNR areas:

• Use porous pavement or open graded friction course in new roads.

• When significant pavement replacement occurs on county roads, use open graded friction course as the new layer.

• Use porous pavement on shoulders (of uncurbed roads) rather than traffic lanes to minimize wear and tear that reduces porosity.

• Encourage property owners to repave existing parking lots with porous pavement, and possibly provide a financial incentive through a rate reduction on stormwater fees.

1.6.6 Cost–Effectiveness Once contractors have experience with OGFC, the cost is essentially the same as for traditional pavements, except in curbed areas. Curbs in areas with OGFC require a linear drainage collection system that gathers water moving laterally through the pavement. ODOT does not use OGFC in urban areas or with curbed roads. However, this is more a matter of policy rather than due to technical or cost limitations (Moore, personal communication). However, in curbed areas the linear drainage collection system could cause conflicts with existing utility lines in the road right-of-way (Moore, personal communication). The value of using OGFC porous pavement is that it significantly reduces the cost of parking lot/street sweeping. The sweeping frequency in commercial areas can be reduced from weekly and biweekly to semi-annually.

1.6.7 Pollutant Load Reduction Data are available from several studies on each of the three paving configurations identified above. A summary of these data is presented below, and potential pollutant loading reductions are discussed.



1.6.7.1 Full Porous Pavement Several studies are available to assess the pollutant removal performance of porous pavements in configurations 1 and 2 (full porous pavement, with or without parent soil that can infiltrate the runoff beneath the pavement). The data reflect the pollutant removal that occurred in the pavement itself, in the pavement plus base coarse material, and/or the entire pavement section plus underlying soil. A study that compared porous and traditional pavements at five sites (Koeleman et al. 1999) found that the porous pavement reduced the loading of six metals by 90 to 97 percent and polycyclic aromatic hydrocarbons (PAH) by 75 percent. It was not stated whether the analysis of runoff from the porous pavement included movement through soil, but this is the likely case given the very high pollutant load reductions.

A study focusing on the pollutant removal capability of just the porous pavement structure (about 12 inches thick) found the concentrations of TSS and zinc to be 64 percent and 72 percent less, respectively, than the runoff from a nearby road segment with standard pavement (Legret et al., 1996). Potential differences between the porous and standard pavement sites may influence the results.

A study of the pollutant removal performance of just the porous pavement structure (apparently using a similar comparative pavement section approach) found about 60 percent removal of both TSS and total zinc (Balades et al. 1995). A laboratory study found 98 percent reduction of petroleum hydrocarbons (Pratt et al. 1999) in a full porous pavement section. Two studies (MWCOG 1983 Hogland et al. 1987) report TSS and total phosphorus reductions of 95 percent, and 60 to 71 percent, respectively, with standard porous pavement.

If there is permeable soil beneath the porous pavement it can be assumed that further pollutant removal will occur in the soil. The specific soil characteristics and pollutant loading passing through the porous pavement will certainly affect the extent of pollutant removal that occurs in the underlying soil.

1.6.7.2 Final Pavement Lift Porous There are fewer studies of pollutant removal effectiveness of porous pavements in configuration 3, such as OGFC (Berbee et al. 1999, Stolz and Krauth 1994). Berbee et al. (1999) calculated pollutant loading reductions (using a nearby standard pavement control area) of 91 percent for TSS and 90 percent for zinc. Mean discharge concentrations were 17 and 0.047 mg/L, respectively. In the second study (Stolz and Krauth 1994), a comparison was not made to a control area, and therefore reduction estimates were not made. However, the discharge concentrations were 56 and 0.596 mg/L, considerably higher than in the first study. This makes any estimates of expected pollutant loading reductions highly uncertain. The very high removal efficiencies in the first study seem unrealistic for a thin layer of asphalt, particularly with respect to zinc, which is highly soluble. This document assumes removal efficiencies of 50, 30, and 30 percent for TSS, total phosphorus, and total zinc, respectively, for roadways with porous pavement only in the top layer. As noted above, the pollutant loading contribution from the streets in commercial areas was observed to be approximately 70, 55, and 45 percent of the total loading for TSS, total phosphorus, and total zinc, respectively (Bannerman et al., 1993). In the same study, parking lots in commercial areas contributed about 27, 28, and 32 percent of the TSS, total phosphorus, and total zinc loading, respectively.

1.6.7.3 Analysis of Pollutant Loading Reductions Based on these data, an analysis of the pollutant loading reductions achievable for runoff from Snohomish County roads was performed. The analysis included pollutant removal in a fully porous pavement section and in a pavement section with only the top layer porous (such as the



ODOT configuration). The analysis assumed that loading reductions for TSS, total phosphorus, and total zinc, using a fully porous pavement cross-section (including infiltration into the soil), would be 95, 60, and 90 percent, respectively.

Table 7 presents the possible pollutant load reductions from streets and parking lots in the commercial areas of Snohomish County. It is not expected that porous pavement retrofit would occur with other land uses.

Table 7. Estimated pollutant loading reductions for two types of porous pavement.

TSS Total Phosphorus Total Zinc

Land Use

Full porous pavement (Lbs/acre/

year)

Final lift porous

(Lbs/acre/ year)


year)

Final lift porous

(Lbs/acre/ year)


year)

Final lift porous

(Lbs/acre/ year)

Streets 200 105 0.23 0.11 0.69 0.23

Parking lots 77 41 0.12 0.06 0.49 0.16

Porous pavement also reduces the volume of runoff (St. John 1997; Thompson and James 1994), which reduces the burden of roadway runoff on stormwater treatment systems that may be present in the road corridor. It also reduces the potential for roadway runoff to contribute to erosion and scour of downstream channels.

1.7 Agricultural BMPs Commercial farms in Snohomish County will soon be required to develop and implement BMP plans under other regulatory programs (Levesque, personal communication), and therefore are not the subject of focus in the DNR studies. There are numerous small, non-commercial farms and private pastures in the DNR study areas that are not covered under other regulatory programs, and those farms and pastures can collectively cause serious water quality degradation if BMPs for water quality protection are not implemented.

Small farms and grazed pastures that are adjacent to streams, ditches, and other surface water conveyance features should implement a variety of BMPs to reduce the potential for surface water quality impairment. These BMPs include:

• Restricting livestock access to streams and ditches with fencing

• Providing alternative watering systems so that livestock do not need to use the stream or ditch for drinking water

• Preventing roof runoff from draining onto areas of bare soil, manure stockpiles, and other areas that can be sources of runoff pollution

• Designating sacrificial pasture areas near a barn or stable for livestock to use in the wet season, with perimeter runoff control, to avoid livestock-induced erosion of pasture areas that are close to streams, wetlands, and other drainage features on the property

• Using compostable bedding material in livestock stalls

• Composting livestock manure



• Planting hedgerows to filter contaminated runoff along the perimeter of pasture areas, particularly on the downslope side of these areas and adjacent to surface water features

• Revegetation of eroding areas, particularly on and near streambanks and near ditches.

The Snohomish Conservation District can provide technical assistance and details on these BMPs.

1.8 Septic System BMPs The first step in an analysis of the potential effects of failing septic systems in a particular DNR study area on receiving waters should be an assessment of the presence or absence of characteristics that create vulnerable conditions for insufficient treatment of wastewater. This type of analysis would entail using GIS to view areas where septic systems are actively used with an overlay of spatial information on soil types, age of development, and depth to ground water (if available). Areas that have a combination of septic system usage, highly porous soils and/or high ground water tables, and older developments could be suspected of contributing potentially significant fecal coliform bacteria and other waste pollutant loads to surface or ground water. The age of developments may not be particularly important, as newer developments could also be associated with septic system problems. Inadequately treated onsite wastewater can seriously degrade receiving water; therefore, geographic areas identified as vulnerable to septic system failure should be further investigated.

If specific septic system problems are identified, the solutions are relatively straightforward. The Snohomish Health District should be consulted for these situations. Septic system drain fields can be reconfigured to provide better treatment of wastewater influent using methods such as low-pressure discharge systems, earthen mounds, and sand-lined drainfield beds. The Snohomish Health District defers specific design approaches for such systems to the criteria and guidelines set forth by Washington State in Chapter 246-272 of the Washington Administrative Code.

1.9 Conclusions

This report provides guidance in the consideration of alternative stormwater treatment BMPs in individual DNR areas. The estimated pollutant loading reductions described in the previous sections are considered reasonable, and provide a consistent basis for selection amongst alternative BMPs. The cost analyses discussed above suggest the following:

• Street sweeping using regenerative-air or high efficiency vacuum equipment is more cost-effective than structural BMPs.

• Cleaning catch basin sumps is more cost-effective than structural BMPs

• Retrofitting of larger, existing detention facilities is likely more cost-effective than constructing stand-alone structural BMPs.

• Where drainage from streets is via ditches, modifying ditches to enhance their pollutant removal effectiveness is cost effective if a basic biofiltration swale can fit in the right-of-way. If catch basins or filtration media need to be added to the design of these ditch retrofits, the cost may become too high to justify that action. Similarly, if new storm drains or culverts would be needed to route runoff into the bioswale, the cost of the pipe trenching may be too high to justify the action, particularly if the trenching would be required across a busy roadway.



The County must consider policy issues related to street and parking lot sweeping. These issues include the purchase of more efficient equipment, sweeping procedures, parking restrictions, and sweeping of private parking lots. Further, if only the streets are swept, the pollutant loading reduction may not be sufficient to provide the desired water quality benefits. This is also the case with cleaning of catch basin sumps.

Where water quality problems are particularly severe, structural BMPs may be required despite the cost. In such cases, the first action should be to incorporate a wet pool into existing onsite detention systems or regional detention systems if they exist or are proposed in a DNR study area.

Analysis of water quality problem areas resulting from inadequate septic systems will require additional GIS data analysis.

Recommendations should be made for BMPs on small farms and private pastures where there is visible evidence of erosion or other evidence of a need for increased water quality protection, particularly where those lands are adjacent to a stream or conveyance ditch.


2.0 References Alter, W., 1994, The changing emphasis of municipal sweeping, American Sweeper, 4, 1, 1994.

Austin (City of), 1996, Evaluation of nonpoint source controls, A319 grant project, Austin, Texas.

Balades, J., M. Legret, and H. Madiec, 1995, Permeable pavements: pollution management tools, Wat. Sci. Tech., 32, 1, 49.

Bannerman, R.T., K. Baun, and V. Bohn, 1983, Evaluation of urban non-point source pollution management in Milwaukee, Wisconsin: Urban stormwater characteristics, sources, and pollutant management by street sweeping, Region V, USEPA.

Bannerman, R.T., R. Dodds, D. Owens, and N.J. Hornewer, 1993, Sources of pollutants in wisconsin stormwater, Wat. Sci. Tech., 28, 241.

Berbee, R., G. Rijs, R. Brouwer, L. Velzen, 1999, Characterization and treatment of runoff from highways in the Netherlands paved with impervious and pervious asphalt, Water. Env. Res., 71, 2, 183.

Blosser, Mark, May 22, 2000, Should the City accept a particulate management street cleaner in lieu of Drainage Manual-required on-site stormwater treatment for the proposed Capital Mall expansion?, City of Olympia, Public Works.

Camomilla, G., M. Malgarin, and S. Gervasio, 1990, Sound absorption and winter performance of porous asphalt pavement, Transp. Res. Rec. 1265, 1.

Colwell, S., R. Horner, and D. Gilvydis, 1999, A survey of ditches along county roads for their potential to affect stormwater runoff water quality, Center for Urban Water Resources Management, University of Washington.

Comings, K.J., 1998, Stormwater pollutant removal for two wet-ponds in the Lake Sammamish watershed, masters thesis, University of Washington.

David Evans & Associates, 1994, Final report: Ecology ditch water quality monitoring, prepared for Washington State Department of Transportation.

Drapper, D., R. Tomlison, and P. Williams, 2000, Pollutant concentrations in road runoff: southeast Queensland case study, J. Environ. Engr., 126, 4, 313.

Driscoll, E.D., P.E. Shelley, and E.W. Strecker, 1990, Pollutant loadings and impacts from highway stormwater runoff, Vol. I: Design Procedure, FHWA-RD-88-006, U.S. Federal Highway Administration, McLean, Virginia.

Ecology, 2001, Stormwater Management Manual for Western Washington, Washington State Department of Ecology.

Galli, J., 1992, Analysis of urban BMP performance and longevity in Prince George’s County, Maryland, Metropolitan Council of Governments, Washington, D.C.

Heystraten, G., and C. Moraux, 1990, Ten years’ experience of porous asphalt in Belgium, Transp. Res. Rec., 1265, 34.



Hilding, K., 1993, A survey of infiltration basins in the Puget Sound region, Masters Thesis, University of California, Davis.

Hogland, W., J. Niemczynowicz, and T. Wahlman, 1987, The unit superstructure during the construction period, Sci. Tot. Env., 59, 411.

Horner, R., 1994, Water quality impacts of urban land use, in Fundamentals of Urban Runoff Management, Terrene Institute, Washington, D.C.

Horner, R., and C. Horner, 1995, Design, construction, and evaluation of a sand filter stormwater treatment system, Part II, Performance monitoring, Alaska Marine Lines, Seattle, Washington.

Hossian, M., and L.A. Scofield, 1991, Porous pavement for control of highway run-off, Arizona Department of Transportation, FHWA-AZ91-352.

Hrachovec, R., and G. Minton, 2001, Field testing of a sock-type catch basin insert, PlanetCPR, Seattle, Washington.

Hubbell, Roth, and Clark (HRC), In association with Pacific Water Resources, 2001, Storm sewer maintenance, final report, City of Livonia, Michigan.

Isenring, T., H. Koster, K. Scazziga, 1990, Experiences with porous asphalt in Switzerland, Transp. Res. Rec., 1265, 51.

Koeleman, M., W.J. Laak, and H. Ietswaart, 1999, Dispersion of PAH and heavy metals along motorways in the Netherlands – an overview, Sci. Tot. Environ., 235, 347.

LBWID. 1998. Watershed and lake BMPs: best management practices appropriate for established urban communities, Lake Barcroft Watershed Improvement District..

Legret, M., V. Colandini, and C.L. Marc, 1996, Effects of porous pavement with reservoir structure on the quality of runoff water and soil, Sci. Tot. Env., 189/190, 335.

Leif, W., 2002, Personal communication (internal review comments provided to Gregg Farris of Snohomish County Surface Water Management regarding a draft version of this technical report).

Levesque, K., 2002, Personal communication (telephone conversation with Mark Ewbank of Herrera Environmental Consultants), Snohomish Conservation District.

Lindsey, G., L. Roberts, and W. Page, 1991, Stormwater management infiltration practices in Maryland: a second survey, Sediment and Stormwater Division, Maryland Department of the Environment.

Minton, G., 1993, Selection of storm water treatment systems for minor road widening, prepared for King County Public Works Roads Division, King County, Washington.

Moore, L., personal communication, pavement engineer, Oregon Department of Transportation.

MWCOG, 1983, Urban runoff in the Washington Metropolitan area: final report, Metropolitan Washington Council of Governments, Washington, D.C..

Pitt, R., and P. Bissonnette, 1984, Bellevue urban runoff program, summary report, City of Bellevue, Washington.

Pitt, R.E., and G. Shawley, 1982, A demonstration of non-point source pollution management on Castro Valley Creek, Alameda County Flood Control and Water Conservation District, Hayward, California.



Pratt, C.J., A.P. Newman, and P.C. Bond, 1999, Mineral oil biodegradation within a permeable pavement: long-term observations, Wat. Sci. Tech., 39, 2, 103.

Sartor, J., and G. Boyd, 1972, Water pollution aspects of street surface contaminants, EPA-R2-72-081.

Sartor, J.D., and D.R. Gaboury, 1984, Street sweeping as a water pollution control measure: lessons learned over the last ten years, Sci. Total Environ., 33, 171.

Schueler, T.R., 1987, Controlling urban runoff: a practice manual for planning and designing urban BMPs, Metropolitan Washington Council of Governments, Washington, D.C.

Shapiro, 1999, Lakemont storm water treatment facility monitoring report, final report, City of Bellevue, Washington, prepared by Shapiro and Associates and the Bellevue Utilities Department.

Shoemaker, L., M. Lahlou, A. Doll, and P. Cazenas, 2000, Stormwater best management practices in ultra-urban setting: selection and methodology, Federal Highway Administration, FHWA-EP-00-002.

Smith, H.A., 1992, Performance characteristics of open-graded friction courses, NCHRP Syntheses of Highway Practice, 180, Transportation Research Board.

St. John, M., 1997, Effect of road shoulder treatments on highway runoff quality and quantity, Washington State Department of Transportation, WA-RD 429.1.

Stolz, S., and K. Krauth, 1994, The pollution of effluents from pervious pavements of an experimental highway section, Sci. Tot. Env., 146/147, 465.

Sutherland, R.C., 2001, personal communication, Pacific Water Resources, Portland, Oregon.

Sutherland, R.C., and S.L. Jelen, 1996, Sophisticated stormwater quality modeling is worth the effort, Advances in modeling the management of stormwater impact, W. James (ed), CHI Publications, Ontario, Canada.

Sutherland, R.C., and S.L. Jelen, 1997, Contrary to conventional wisdom: street sweeping can be an effective BMP, Advances in modeling the management of stormwater impact, W. James (ed), CHI Publications, Ontario, Canada.

Sutherland, R.C., S.L. Jelen, and G. Minton, 1997, Stormwater treatment BMP evaluation, prepared for the Port of Seattle, Seattle, Washington.

Tetra Tech, Inc, in association with Pacific Water Resources, 2001, Quantifying the impact of catch basin and street sweeping on stormwater quality for a Great Lakes tributary: pilot study (draft), Grand River Inter-County Drainage Board, Michigan.

Thompson, M.K., and W. James, 1994, Provision of parking lot pavements for surface water pollution control, in Urban stormwater modeling and simulation, S.J. Nik (ed), Lewis Publishers, Chelsea, Michigan.

U.S. Environmental Protection Agency (USEPA), 1983, Final report of the nationwide urban runoff program.

USEPA, 1986, Methodology for analysis of detention basins for control of urban runoff, EPA440/5-87-001.

USEPA, 1999, Storm water technology fact sheet: porous pavement, EPA832-F-99-023.

Winer, R., 2000, National pollutant removal performance database, Center for Watershed Protection, Ellicott, Maryland.



Woodward Clyde, 1994a, Storm inlet pilot study, Alameda County Urban Runoff Cleanwater Program, California.

Woodward-Clyde, 1994, San Jose street sweeping equipment evaluation, City of San Jose, California.

Young, G.K., S. Stein, P. Cole, T. Kammer, F. Graziano, F. Bank, 1996, Evaluation and management of highway runoff water quality, FHWA-PD-96-032.

Younger, K., R.G. Hicks, and J. Gower, 1994, Final report: evaluation of porous pavements used in Oregon, Oregon Department of Transportation, TRI #94-17.


3.0 Addendum

Cost Data and Estimated Pollutant Removal for Various Structural Treatment BMPs Analyzed and/or Constructed in the Pacific Northwest in Recent Years

# BMP Type Context Area Land Use Cost Cost Year

Adjusted to 2002

Annual Cost

Annual Mainten.

Total Annual $

Influent TSS-lbs BMP Eff.

$/Lb Removed

BMP $/Lb Ave

BMP $/Lb med

1 Wetpond New 6.1 MDSFR $45,000 2001 $46,350 $3,105 $3,105 $6,210 793 0.80 $9.79 5

Wetpond New 7.5 Comm $68,000 2001 $70,040 $4,693 $3,105 $7,797 2250 0.80 $4.33 7 Wet pond Retrofit 27 LDSFR $216,000 1998 $243,110 $16,288 $3,105 $19,393 1620 0.80 $14.96 31 Wet pond Retrofit 31.5 MDSFR $52,000 2001 $53,560 $3,589 $3,105 $6,693 4095 0.80 $2.04 32 Wet pond Retrofit 13 MDSFR $30,000 2001 $30,900 $2,070 $3,105 $5,175 1690 0.80 $3.83 $6.99 $4.33

2 Wet vault New 0.8 Comm $57,000 2001 $58,710 $3,934 $2,627 $6,560 240 0.80 $34.17 3

Wet vault New 1 Comm $72,000 2001 $74,160 $4,969 $2,627 $7,596 300 0.80 $31.65 12 Wet vault New 0.42 Comm $50,000 2000 $53,045 $3,554 $2,627 $6,181 126 0.80 $61.32 17 Wet vault New 5.5 Comm $149,000 1999 $162,816 $10,909 $2,627 $13,536 1650 0.80 $10.25 18 Wet vault New 12.9 Comm $149,000 1999 $162,816 $10,909 $2,627 $13,536 3870 0.80 $4.37 19 Wet vault New 6.9 Comm $149,000 1999 $162,816 $10,909 $2,627 $13,536 2070 0.80 $8.17 20 Wet vault New 14.4 Comm $167,000 1999 $182,485 $12,227 $2,627 $14,853 4320 0.80 $4.30 $22.03 $10.25

4 Sand filter New 1 Comm $50,000 2001 $51,500 $3,451 $3,582 $7,033 300 0.90 $26.05 6

Sand filter New 10 Comm $106,000 2001 $109,180 $7,315 $3,582 $10,897 3000 0.90 $4.04 9 Sand filter Retrofit 27 LDSFR $203,000 1998 $228,478 $15,308 $3,582 $18,890 1620 0.90 $12.96 $14.35 $12.96

8 Swale Retrofit 27 LDSFR $50,000 1998 $56,275 $3,770 $1,194 $4,965 1620 0.70 $4.38 13

Swale New 5.5 Comm $2,310 1999 $2,524 $169 $1,194 $1,363 1650 0.70 $1.18 14 Swale New 12.9 Comm $1,955 1999 $2,136 $143 $1,194 $1,337 3870 0.70 $0.49 15 Swale New 6.9 Comm $1,836 1999 $2,006 $134 $1,194 $1,328 2070 0.70 $0.92 16 Swale New 14.4 Comm $4,443 1999 $4,855 $325 $1,194 $1,519 4320 0.70 $0.50 $1.49 $0.92

X011084_3538 3.0 Addendum 3-1 December 2002


X011084_3538 3.0 Addendum 3-2 December 2002

# BMP Type Context Area Land Use Cost Cost Year

Adjusted to 2002

Annual Cost

Annual Mainten.

Total Annual $

Influent TSS-lbs BMP Eff.

$/Lb Removed

BMP $/Lb Ave

BMP $/Lb med

10 O/w separ. Retrofit 30 Indus $1,100,000 1994 $1,393,447 $93,361 $1,114 $94,475 9000 0.50 $20.99 11

O/w separ. Retrofit 5 Indus $200,000 1994 $253,354 $16,975 $1,114 $18,089 1500 0.50 $24.12 21 O/w separ. New 5.5 Comm $59,000 1999 $64,471 $4,320 $1,114 $5,434 1650 0.50 $6.59 22 O/w separ. New 12.9 Comm $59,000 1999 $64,471 $4,320 $1,114 $5,434 3870 0.50 $2.81 23 O/w separ. New 6.9 Comm $59,000 1999 $64,471 $4,320 $1,114 $5,434 2070 0.50 $5.25 24 O/w separ. New 14.4 Comm $58,000 1999 $63,378 $4,246 $1,114 $5,360 4320 0.50 $2.48 $10.37 $5.92

29 Stormfilter New 5.13 Comm $30,000 1999 $32,782 $2,196 $5,000 $7,196 1539 0.60 $7.79 33

Stormfilter New 0.25 Road 18000 1995 $22,138 $1,483 $1,230 $2,713 63 0.70 $62.01 34 Stormfilter New 0.7 Road 18000 1995 $22,138 $1,483 $1,230 $2,713 175 0.70 $22.15

30 Vortech New 7.2 Comm $35,500 2001 $48,611 $3,257 $2,500 $5,757 2160 0.60 $4.44

Volume V Cost Estimating

Unit Prices

��



425-388-3464

Cost Estimating Unit Prices

Unit Costs Development The DNR Unit Prices are based on Snohomish County and other Puget Sound bid tabs. They are appropriate for common applications without unusual project conditions or constraints that may cause them to vary up or down. These prices are also quantity sensitive. For these reasons, they should be assessed on a project specific basis. If specific projects require special consideration of these unit prices, make appropriate adjustments and document justification. Unit costs are Based on ENR's 2001 index for Seattle and in light of the current (December 2001) economic and construction market status, the costs below were determined to represent 2002 dollars. For specific costs see the Unit Cost table. Backup for various unit costs are provided as indicated in the Unit Cost Table. Project cost estimates include easement acquisition for public projects that cross private property boundaries. A $7,000 per parcel fee is used for easement acquisition. Project cost estimates for improvements to storm drainage systems along public roads which require work outside of the public ROW do not include easement acquisition. Private drainage system improvement projects do not include easement costs. A private drainage system is defined as a system that is intended to collect runoff from private property only (i.e. only connects to the public system at the downstream end of the private system), and is located on private property. Projects that require land acquisition use average costs for specific land use types. Assessed land values are collected for the different land use types in each DNR area. A 20% markup for market values, 20% markup for condemnation values, and $7,000 administrative fee is applied to the assessed values. The adjusted prices are averaged and applied to the appropriate project costs. A 30% contingency is typically applied to these land acquisition costs. However, this contingency is not applied to projects with land acquisition for habitat restoration projects.

X011084_3538 Cost Estimating Unit Prices 1 December 2002

Attachment Unit Costs

NOTE: The DNR Unit Prices are based on Snohomish County and other Puget Sound bid tabs. They areappropriate for common applications without unusual project conditions or constraints that may cause themto vary up or down. These prices are also quantity sensitive. For these reasons, they should be assessedon a project specific basis. If specific projects require special consideration of these unit prices, makeappropriate adjustments and document justification.

Based on ENR's 2001 index for Seattle and in light of the current (December 2001) economic andconstruction market status, the costs below were determined to represent 2002 dollars.

UnitCode Material Description Unit Unit Prices

CLEARING, GRUBBING, AND ROADSIDE CLEANUP

1 CLEARING AND GRUBBING SF $2.002 CLEARING AND GRUBBING AC $5,000.00

3 REMOVE AND REPLACE ROCKERY CY $150.004 REMOVE CEM. CONC. SIDEWALK SY $17.50

5 REMOVE PAVEMENT SY $20.00including sawcut, removal, disposal

6 REMOVE CURB AND GUTTER LF $9.257 REMOVE CULVERT LF $12.008 REMOVE FENCE, WOOD LF $7.009 REMOVE FENCE, CHAIN LINK LF $4.50

10 REMOVE PIPE LF $15.0011 REMOVE CATCH BASIN EA $300.0012 REMOVE INLET EA $260.0013 REMOVE MANHOLE EA $645.0014 REMOVE SCRUB EA $450.0015 REMOVE SIGN EA $85.0016 REMOVE TREE EA $480.0017 SAW ASPHALT CONCRETE FULL DEPTH LF $4.5018 SAW CEMENT CONCRETE, 2-INCH MIN.DEPTH LF $5.0019 SAW CEMENT CONCRETE, FULL DEPTH LF $6.5020 ABANDON CATCH BASIN EA $260.0021 ABANDON INLET EA $250.0022 ABANDON MANHOLE EA $440.0023 ABANDON AND FILL PIPE LF $20.00

24 UTILITY RELOCATION LS $10,000 TO $40,000

Based upon CH2M Hill experience in project area. Adust as judged appropriate.

25 COMMON EXCAVATION {QTY >= 1000} CY $15.0026 COMMON EXCAVATION {QTY < 1000} CY $27.0027 STRUCTURE EXCAVATION CY $29.0028 CHANNEL EXCAVATION CY $16.0029 REGRADE EXISTING DITCH LF $5.00

30 CRUSHED SURFACE BASE COURSE TN $23.0031 CRUSHED SURFACE TOP COURSE TN $30.0032 WASHED DRAIN ROCK TN $23.0033 GRAVEL BORROW TN $23.0034 STREAM GRAVEL TN $36.0035 PIPE BEDDING TN $23.0036 RIPRAP, LIGHT LOOSE TN $48.0037 RIPRAP, 2 IN TO 6 IN QUARRY SPALLS TN $45.0038 QUARRY SPALLS TN $45.0039 CONTROLLED DENSITY FILL CY $95.0040 BOULDERS TN $50.00

41 ROUND RIVER ROCK TN $40.00


42 FILL FOR POND BERMS TN $12.00 see new unit costs 8-12-02

43 PAVEMENT, CEM CONC WITH BASE SY $80.0044 PAVMT PATCH, CEM CONC CL 6.5 (1-1/2), HES SY $240.0045 PAVEMENT, ASPHALT CONCRETE CL A {QTY < 500} TN $106.0046 PAVEMENT, ASPHALT CONCRETE CL B {QTY < 500} TN $80.0047 PAVEMENT, ASPHALT CONCRETE CL E {QTY < 500} TN $80.0048 ASPHALT CONCRETE PAVEMENT PATCHING TN $100.0049 ASPHALT TREATED BASE TN $90.00

REMOVAL OF STRUCTURES AND OBSTRUCTIONS

ROADWAY EXCAVATION

MINERAL AGGREGATES

DNR Unit Prices

PAVEMENT

X011084_3538 1 of 24Unit Costs for Snohomish County Drainage Needs Reports

December 2002


DNR Unit Prices

50 12" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE LF $35.0051 18" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE LF $50.0052 24" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE LF $65.0053 30" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE LF $85.00 see new unit costs 8-12-0254 36" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE LF $100.00

5512" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE, JACK AND BORE CONSTRUCTION LF $320.00 see new unit costs 8-12-02





60 JACKING AND RECEIVING PITS EA $35,500.00 see new unit costs 8-12-0261 CLEANOUT, 8 IN EA $955.0062 REINF. CONC. PIPE 12-INCH LF $40.0063 REINF. CONC. PIPE 15-INCH LF $45.0064 REINF. CONC. PIPE 18-INCH LF $50.0065 REINF. CONC. PIPE 21-INCH LF $60.0066 REINF. CONC. PIPE 24-INCH LF $70.0067 REINF. CONC. PIPE 30-INCH LF $100.0068 REINF. CONC. PIPE 36-INCH LF $115.0069 REINF. CONC. PIPE 42-INCH LF $160.0070 REINF. CONC. PIPE 48-INCH LF $170.0071 REINF. CONC. PIPE 54-INCH LF $230.0072 REINF. CONC. PIPE 60-INCH LF $300.0073 REINF. CONC. PIPE 66-INCH LF $340.0074 REINF. CONC. PIPE 72-INCH LF $380.0075 REINF. CONC. PIPE 84-INCH LF $440.0076 REINF. CONC. PIPE 96-INCH LF $500.0077 REINF. CONC. PIPE 108-INCH LF $615.0078 CORRUGATED METAL PIPE 12-INCH LF $22.0079 CORRUGATED METAL PIPE 18-INCH LF $35.0080 CORRUGATED METAL PIPE 24-INCH LF $40.0081 CORRUGATED METAL PIPE 30-INCH LF $60.0082 CORRUGATED METAL PIPE 36-INCH LF $75.0083 CORRUGATED METAL PIPE 42-INCH LF $80.0084 CORRUGATED METAL PIPE 48-INCH LF $90.0085 CORRUGATED METAL PIPE 54-INCH LF $105.0086 CORRUGATED METAL PIPE 60-INCH LF $140.0087 CORRUGATED METAL PIPE 66-INCH LF $265.0088 CORRUGATED METAL PIPE 72-INCH LF $300.0089 HELICAL WELD CORRUGATED METAL PIPE 84-INCH LF $340.0090 HELICAL WELD CORRUGATED METAL PIPE 96-INCH LF $390.0091 HELICAL WELD CORRUGATED METAL PIPE 108-INCH LF $440.0092 CORRUGATED METAL PIPE 144-INCH LF $580.00

93 CORRUGATED METAL PIPE ARCH 21"X 15" (EQUIV. DIA 18") LF $40.0094 CORRUGATED METAL PIPE ARCH 24" X 18" LF $45.00 see new unit costs 9-06-0295 CORRUGATED METAL PIPE ARCH 28"X 20" (EQUIV. DIA 24") LF $45.0096 CORRUGATED METAL PIPE ARCH 35"X 24" (EQUIV. DIA 30") LF $70.0097 CORRUGATED METAL PIPE ARCH 42"X 29" (EQUIV. DIA 36") LF $85.0098 CORRUGATED METAL PIPE ARCH 49"X 33" (EQUIV. DIA 42") LF $95.0099 CORRUGATED METAL PIPE ARCH 57"X 38" (EQUIV. DIA 48") LF $100.00100 CORRUGATED METAL PIPE ARCH 60"x48" LF $115.00 See Allen projects backup101 CORRUGATED METAL PIPE ARCH 64"X 43" (EQUIV. DIA 54") LF $115.00102 CORRUGATED METAL PIPE ARCH 64.8"x49.2" LF $115.00 See Allen projects backup103 CORRUGATED METAL PIPE ARCH 66"x30" LF $110.00 See Allen projects backup104 CORRUGATED METAL PIPE ARCH 66"x54" LF $150.00 See Allen projects backup105 CORRUGATED METAL PIPE ARCH 66"x60" LF $160.00 See Allen projects backup106 CORRUGATED METAL PIPE ARCH 66"x66" LF $200.00 See Allen projects backup107 CORRUGATED METAL PIPE ARCH 71"X 47" (EQUIV. DIA 60") LF $160.00108 CORRUGATED METAL PIPE ARCH 72"x54" LF $190.00 See Allen projects backup109 CORRUGATED METAL PIPE ARCH 72"x60" LF $310.00 See Allen projects backup110 CORRUGATED METAL PIPE ARCH 72"x62.4" LF $320.00 See Allen projects backup111 CORRUGATED METAL PIPE ARCH 72"x66" LF $325.00 See Allen projects backup112 CORRUGATED METAL PIPE ARCH 72"x78" LF $350.00 See Allen projects backup113 CORRUGATED METAL PIPE ARCH 77"X 52" (EQUIV. DIA 66") LF $290.00114 CORRUGATED METAL PIPE ARCH 83"X 57" (EQUIV. DIA 72") LF $330.00115 CORRUGATED METAL PIPE ARCH 96" X 50.4" LF $400.00 see new unit costs 9-06-02116 CORRUGATED METAL PIPE ARCH 103" X 71" LF $500.00 see new unit costs 8-12-02117 CORRUGATED METAL PIPE ARCH 108" X 56" LF $500.00 see new unit costs 8-12-02

118 CORRUGATED METAL PIPE ARCH (112' X 76") (9.3' SPAN x 6.3' RISE) LF $550.00

Cost was adjusted by nhc to match range of previously priced culverts

PIPES

ARCH PIPES AND CULVERTS

(Cost includes trench excavation, trench box, bedding, disposal of unsuitable materials, pipe, and installation)

(Cost includes trench excavation, trench box, bedding, disposal of unsuitable materials, pipe, and installation.)


December 2002


DNR Unit Prices

119 CORRUGATED METAL PIPE ARCH (128' X 83") (10.7' SPAN x 6.9' RISE) LF $650.00

j ymatch range of previously priced culverts

120 STRUCTURAL PLATE METAL ARCH (156" X 61") (13' x 5' 1") LF $600.00


121 METAL PLATE ARCH 156" X 96" LF $660.00 See Allen projects backup122 CORRUGATED METAL PIPE ARCH 168" X 56.4" LF $700.00 see new unit costs 9-06-02

123 CORRUGATED METAL PIPE ARCH 179" X 118" (14.9' SPAN x 9.83' RISE) LF $800.00




125 STRUCTURAL PLATE METAL ARCH (204" X 62.5") (17' x 5' 2.5") LF $740.00




127 REINF. CONC. BOX CULVERT 132-INCH X 84-INCH LF $1,550.00 See Allen projects backup128 REINF. CONC. BOX CULVERT 72-INCH X 24-INCH LF $550.00129 REINF. CONC. BOX CULVERT 72-INCH X 36-INCH LF $680.00130 REINF. CONC. BOX CULVERT 66-INCH X 78-INCH LF $800.00131 REINF. CONC. BOX CULVERT 66-INCH X 74.4-INCH LF $860.00 See Allen projects backup132 REINF. CONC. BOX CULVERT 66-INCH X 60-INCH LF $800.00 See Allen projects backup133 REINF. CONC. BOX CULVERT 66-INCH X 48-INCH LF $740.00 See Allen projects backup134 REINF. CONC. BOX CULVERT 57-INCH X 60-INCH LF $770.00 See Allen projects backup135 REINF. CONC. BOX CULVERT 54-INCH X 36-INCH LF $640.00 See Allen projects backup136 REINF. CONC. BOX CULVERT 24-INCH X 24-INCH LF $370.00 see new unit costs 8-12-02137 REINF. CONC. BOX CULVERT 36-INCH X 30-INCH LF $430.00 see new unit costs 8-12-02138 REINF. CONC. BOX CULVERT 42-INCH X 30-INCH LF $510.00 see new unit costs 8-12-02139 REINF. CONC. BOX CULVERT 48-INCH X 24-INCH LF $490.00 See NHC Unit Cost 10-22-02140 REINF. CONC. BOX CULVERT 54-INCH X 42-INCH LF $490.00 see new unit costs 8-12-02141 REINF. CONC. BOX CULVERT 60-INCH X 48-INCH LF $690.00 see new unit costs 8-12-02142 REINF. CONC. BOX CULVERT 30-INCH X 24-INCH LF $380.00 see new unit costs 8-12-02143 REINF. CONC. BOX CULVERT 40-INCH X 36-INCH LF $560.00 see new unit costs 8-12-02144 REINF. CONC. BOX CULVERT 48-INCH X 36-INCH LF $560.00 see new unit costs 8-12-02145 REINF. CONC. BOX CULVERT 72-INCH X 36-INCH LF $850.00 see new unit costs 8-12-02146 REINF. CONC. BOX CULVERT 72-INCH X 48-INCH LF $870.00 see new unit costs 8-12-02147 REINF. CONC. BOX CULVERT 36-INCH X 24-INCH LF $410.00 see new unit costs 9-06-02148 REINF. CONC. BOX CULVERT 36-INCH X 36-INCH LF $440.00 see new unit costs 9-06-02149 REINF. CONC. BOX CULVERT 42-INCH X 36-INCH LF $530.00 see new unit costs 9-06-02150 REINF. CONC. BOX CULVERT 10' SPAN x 3' RISE LF $830.00 See NHC Unit Cost 10-22-02151 REINF. CONC. BOX CULVERT 10' SPAN x 3.5' RISE LF $910.00 See NHC Unit Cost 10-22-02152 REINF. CONC. BOX CULVERT 10' SPAN x 4' RISE LF $990.00 See NHC Unit Cost 10-22-02153 REINF. CONC. BOX CULVERT 10' SPAN x 5' RISE LF $1,150.00 See NHC Unit Cost 10-22-02154 REINF. CONC. BOX CULVERT 10.79' SPAN x 7' RISE LF $1,550.00 See NHC Unit Cost 10-22-02155 REINF. CONC. BOX CULVERT 11' SPAN x 3.5' RISE LF $970.00 See NHC Unit Cost 10-22-02156 REINF. CONC. BOX CULVERT 11' SPAN x 4' RISE LF $1,050.00 See NHC Unit Cost 10-22-02157 REINF. CONC. BOX CULVERT 12' SPAN x 3.5' RISE LF $1,020.00 See NHC Unit Cost 10-22-02158 REINF. CONC. BOX CULVERT 12' SPAN x 5' RISE LF $1,300.00 See NHC Unit Cost 10-22-02159 REINF. CONC. BOX CULVERT 12' SPAN x 5.5' RISE LF $1,400.00 See NHC Unit Cost 10-22-02160 REINF. CONC. BOX CULVERT 13' SPAN x 3.5' RISE LF $1,080.00 See NHC Unit Cost 10-22-02161 REINF. CONC. BOX CULVERT 13' SPAN x 4' RISE LF $1,180.00 See NHC Unit Cost 10-22-02162 REINF. CONC. BOX CULVERT 15' SPAN x 4' RISE LF $1,300.00 See NHC Unit Cost 10-22-02163 REINF. CONC. BOX CULVERT 15' SPAN x 5' RISE LF $1,540.00 See NHC Unit Cost 10-22-02164 REINF. CONC. BOX CULVERT 18' SPAN x 5' RISE LF $1,770.00 See NHC Unit Cost 10-22-02165 REINF. CONC. BOX CULVERT 22' SPAN x 4' RISE LF $1,740.00 See NHC Unit Cost 10-22-02166 REINF. CONC. BOX CULVERT 26' SPAN x 5' RISE LF $2,400.00 See NHC Unit Cost 10-22-02167 REINF. CONC. BOX CULVERT 30' SPAN x 6' RISE LF $3,180.00 See NHC Unit Cost 10-22-02168 REINF. CONC. BOX CULVERT 36' SPAN x 12' RISE LF $4,500.00 See NHC Unit Cost 10-22-02169 REINF. CONC. BOX CULVERT 48' SPAN x 12' RISE LF $5,860.00 See NHC Unit Cost 10-22-02

170 CONCRETE INLET EA $900.00171 CATCH BASIN TYPE 1 EA $1,330.00172 CATCH BASIN TYPE 1L EA $1,950.00173 CATCH BASIN TYPE 2 48" EA $2,940.00174 CATCH BASIN TYPE 2 54" EA $3,780.00175 CATCH BASIN TYPE 2 72" EA $6,500.00176 CATCH TYPE 2 84" EA $8,000.00177 CATCH BASIN TYPE 2 96" EA $12,250.00178 CATCH BASIN TYPE 2 120" EA $21,000.00179 CATCH BASIN TYPE 2 144" EA $24,000.00180 EXTRA DEPTH, ALL TYPES VF $400.00

CONCRETE BOX CULVERTS

CATCH BASINS, AND INLETS




December 2002


DNR Unit Prices

181 FLOW CONTROL STRUCTURE, 48-INCH EA $4,000.00182 FLOW CONTROL STRUCTURE, 54-INCH EA $6,100.00183 FLOW CONTROL STRUCTURE, 72-INCH EA $10,200.00184 FLOW CONTROL STRUCTURE, 96-INCH EA $27,300.00185 96" FLOW CONTROLLER MANHOLE (<12 FT.) EA $23,000.00186 96" FLOW CONTROLLER MANHOLE (>12 FT.) EA $34,000.00187 FLOW CONTROL STRUCTURE, 120-INCH EA $40,000.00188 PIPE, DETENTION, CONC, 24-INCH LF $150.00189 PIPE, DETENTION, CONC, 30-INCH LF $270.00190 PIPE, DETENTION, CONC, 54-INCH LF $600.00191 PIPE, DETENTION, CONC, 60-INCH LF $750.00192 FLOW CONTROL (FROP-T) DEVICE EA $840.00193 EROSION CONTROL LS % VARIES194 8" SIDE OUTLET CIRCULAR ORIFICE EA $300.00195 OUTLET STRUCTURE LS $2,000.00196 FLOW SPLITTER LS $4,000 - $7,500 Small to large

197 CONNECT TO EXISTING DRAINAGE STRUCTURE EA $500.00WashDOT Standard Item Table, dated 10/09/2000

198 PLUG EXISTING PIPE EA $100.00WashDOT Standard Item Table, dated 10/09/2000

199 EROSION CONTROL, HYDRO-SEEDING {QTY < 1000} SF $3.00200 EROSION CONTROL, HYDRO-SEEDING {1000 <= QTY < 5000} SF $0.75201 EROSION CONTROL, HYDRO-SEEDING {QTY >= 5000} SF $0.15202 EROSION CONTROL, MATTING, JUTE SF $0.90203 EROSION CONTROL, MATTING, WOOD EXCELSIOR SF $0.80204 FENCE, TEMPORARY SILT CONTAINMENT LF $7.80

205 TOPSOIL CY $28.00206 SODDING {QTY < 1000} SF $2.00207 SODDING {QTY >= 1000} SF $1.20208 SEEDED LAWN INSTALLATION {QTY < 10,000} SF $0.60209 SEEDED LAWN INSTALLATION {QTY >= 10,000} SF $0.10210 ROADSIDE PLANTING/LANDSCAPING SY $25.00211 TREE EA $135.00212 SHRUB EA $15.00213 BEDDING, SPECIAL CDF CY $300.00214 WET POND SEEDING SF $1.50

215 CURB, CEMENT CONC. LF $15.70216 CURB AND GUTTER, CEMENT AND CONC. LF $19.30217 CURB, EXTRUDED ASPHALT CONCRETE (ASPHALT BERM) LF $6.50218 CURB, EXTRUDED CEMENT CONCRETE LF $8.20219 ASPHALT SWALE LF $20.00 Seattle 2001 bid tabs

220 LIVESTOCK CONTROL FENCE LF $5.00221 CHAIN LINK FENCE LF $12.00222 CHAIN LINK GATE 6 FT WIDE EA $479.00223 CHAIN LINK GATE 12 FT WIDE EA $600.00224 CHAIN LINK GATE 14 FT WIDE EA $630.00225 CHAIN LINK GATE 20 FT WIDE EA $1,175.00226 REMOVE & REINSTALL CHAIN LINK FENCE LF $15.00

227 SIDEWALK CEMENT CONCRETE {QTY < 500} SY $33.00228 SIDEWALK CEMENT CONCRETE {QTY >= 500} SY $23.00229 CURB RAMP, CEMENT CONCRETE EA $425.00230 DRIVEWAY, CEMENT CONCRETE, 6-INCH SY $35.00231 DRIVEWAY, CEMENT CONCRETE, 8-INCH SY $38.00

232 ROCK FACING SF $16.00233 STRUCTURAL CONCRETE CY $500.00234 CONCRETE CLASS A (INCLUDES FORMS AND REBAR) CY $1,600.00235 EMBANKMENT COMPACTION CY $2.00236 STRUCTURAL FILL (INCLUDING COMPACTION) CY $15.00237 ACCESS ROAD (15' WIDE, 6" GRAVEL DEPTH) LF $17.00

CHAIN LINK FENCE AND GATES

CEMENT CONCRETE SIDEWALKS AND DRIVEWAYS

FLOW CONTROL SYSTEMS

CURB AND GUTTER

EROSION CONTROL

LANDSCAPING

MISC ITEMS



December 2002


DNR Unit Prices

238 GABIONS (WITH ROAD ACCESS) CY $175.00239 GABIONS (WITHOUT ROAD ACCESS) CY $275.00240 TRASH RACK EA $500.00

241 REVEGETATION (RELOCATION OF RIPARIAN CORRIDOR) AC $30,000.00

Provided by Snohomish County. Assume revegetation of 200 foot riparian corridor width (100 feet per side).

242 REVEGETATION (TREE AND SHRUB SUPPLEMENTATION IN RIPARIAN CORRIDOR) AC $3,000.00

Provided by Snohomish County. Assume revegetation of 200 foot riparian corridor width (100 feet per side).

243 BIOENGINEERING BANK STABILIZATION LF $100.00Based on CH2M Hill Coeur d'Alene project, May 2000

244 FISH HABITAT STRUCTURE (ROOT WAD) EA $200.00

245 LARGE WOODY DEBRIS EA $800.00small quantity, not immediately available

246 LOG FISH WEIR (Includes installation) EA $2,000.00Based on recent projects, by L Gibbons, Tetra Tech/KCM

247 BIOSWALE CONSTRUCTION (INCLUDES EXCAVATION GRADING AND SEEDING SF $5.00248 STORMFILTER SYSTEM LS $100,000.00

249 CATTLE FENCING LF $5.00PROVIDED BY HANS EHLERT, CH2M Hill

250PRE-CAST SINGLE SPAN CONCRETE BRIDGE DECK WITH CONCRETE ABUTMENTS (MAXIMUMLENGTH = 150') SF $125.00

Provided by Paul Guenther, CH2M Hill

251 RAILSPAN BRIDGE EA $14,000Provided by Scott Gibbs Company

252 EQUIPMENT - CRANE (RAILSPAN BRIDGE CONSTRUCTION) EA $1,600Provided by Scott Gibbs Company

253 DELIVERY - RAILSPAN BRIDGE EA $2,000Provided by Scott Gibbs Company

254 DEWATERING LSAllowance (see

template)

Where expected to be required based on engineers experience and judgement. Adjust as judged appropriate.

255 TEMPORARY BYPASS LS $5,000 TO $20,000


256 EROSION & SEDIMENTATION CONTROL LS 10%

Increase percentage markup if work is in or immmediately adjacent to flowing or standing water, steep slope,

257and/or other erosion prone conditions.

258 TRAFFIC CONTROL LS 3%

Increase percentage markup if work is in or immediatesly adjacent to secondary, arterial or other high volume

259road or are closing a roadway temporarily.

260 CONTINGENCY LS 30%

261 CONTINGENCY FOR HABITAT PROJECTS CONSISTING OF PLANTING ONLY LS 10%-15%Based on comments from Gregg Farris

262 MOBILIZATION (GENERAL REQUIREMENTS) LS 10%263264 ENGINEERING/LEGAL/ADMIN: % / MINIMUM265 CONSTRUCTION COST RANGE $0 TO $10,000 LS 100% / $10,000266 CONSTRUCTION COST RANGE $10,000 TO $50,000 LS 85% / $10,000267 CONSTRUCTION COST RANGE $50,000 TO $100,000 LS 50% / $40,000268 CONSTRUCTION COST RANGE $100,000 TO $250,000 LS 35% / $50,000269 CONSTRUCTION COST RANGE >$250,000 LS 25% / $90,000

270 HABITAT PROJECTS CONSISTING OF PLANTING ONLY LS 10%Based on comments from Gregg Farris

271272 CONSTRUCTION MANAGEMENT LS 20%273274 PERMITTING: % 275 CONSTRUCTION COST RANGE $0 TO $50,000 LS 20% 276 CONSTRUCTION COST RANGE $50,000 TO $250,000 LS 10% 277 CONSTRUCTION COST RANGE >$250,000 LS 5%

278 HABITAT PROJECTS CONSISTING OF LARGE WOODY DEBRIS ONLY LS 10% (max)Based on comments from Gregg Farris

279 CULVERT REPLACEMENT FOR FISH PASSAGE ONLY LS 10% (max)Based on comments from Gregg Farris

280 HABITAT PROJECTS CONSISTING OF PLANTING ONLY LS 0%Based on comments from Gregg Farris

281 SALES TAX LS 8.5%Non PTBA areas, 8.9% in PTBA areas

OTHER ITEMS


December 2002

Attachment Unit Costs Backup #1

Item No. Material Unit CH2M WSDOT BIDs Sno. Co. Bids Seattle Bids Seattle Culvert Bids Average Material Cost Ratio Previous MDP Unit Prices

Updated MDP Unit Prices Comments

1 Clearing and Grubbing SF $1.84 $2.00 $1.92 $2.00

Clearing and Grubbing AC $5,000.00for larger areas, treed, haul & dispose

2 Remove Cem. Conc. Sidewalk SY $19.00 $15.75 $17.38 $17.50

3 Remove Pavement SY $20.00 $11.00 $18.00 $14.50 $14.50including sawcut, removal, transport, disposal

4 Remove Culvert LF $12.00 $12.00 $12.005 Remove Fence, Wood LF $7.00 $7.00 $7.006 Remove Fence, Chain Link LF $5.50 $3.00 $4.25 $4.257 Remove Pipe LF $15.00 $15.00 $15.008 Remove Catch Basin EA $300.00 $300.00 $300.009 Remove Inlet EA $250.00 $270.00 $260.00 $260.0010 Remove Manhole EA $605.00 $680.00 $642.50 $642.5011 Remove Scrub EA $450.00 $450.00 $450.0012 Remove Sign EA $85.00 $85.00 $85.0013 Remove Tree EA $480.00 $480.00 $480.0014 Saw Asphalt Concrete Full Depth LF $4.20 $4.20 $4.2015 Saw Cement Concrete, 2-inch Min.Depth LF $5.10 $5.10 $5.1016 Saw Cement Concrete, Full Depth LF $6.50 $6.50 $6.5017 Abandon Catch Basin EA $260.00 $260.00 $260.0018 Abandon Inlet EA $250.00 $250.00 $250.0019 Abandon Manhole EA $360.00 $515.00 $437.50 $437.5020 Abandon and Fill Pipe LF $20.00 $20.00 $20.00

21 Common Excavation {QTY >= 1000} CY $13.00 $11.10 $21.50 $15.20 $15.20Common Excavation {QTY < 1000} CY $20.00 $33.00 $28.00 $27.00 $15.00 $27.00

22 Structure Excavation CY $30.00 $20.00 $36.25 $28.75 $28.7523 Channel Excavation CY $16.00 $16.00 $20.00 $16.00

Regrade Existing Ditch LF $5.00 40'/hours @ $200/hour

24 Crushed Surface Base Course TN $23.00 $23.00 $9.00 $23.0025 Crushed Surface Top Course TN $27.00 $32.00 $29.50 $9.00 $25.00 $29.5025 Washed Drain Rock TN $23.00 $10.00 15 for material + placement26 Gravel Borrow TN $23.00 $21.70 $22.35 $7.75 $20.00 $22.3527 Stream Gravel TN $36.00 $36.00 $30.00 $36.0028 Pipe Bedding TN $23.00 $23.00 $23.0029 RipRap, Light Loose TN $41.00 $55.00 $48.00 $48.00

Riprap, 2 to 6" TN $29.00 20 for material + placement30 Quarry Spalls TN $44.00 $46.00 $45.00 $45.0031 Controlled Density Fill CY $102.00 $86.00 $95.00 $94.33 $94.33

Boulders TN $50.00

32 Pavement, Asphalt Concrete Cl A {QTY < 500} TN $107.00 $105.00 $106.00 $106.0033 Pavement, Asphalt Concrete Cl B {QTY < 500} TN $85.00 $72.00 $78.50 $77.00 $78.5034 Pavement, Asphalt Concrete Cl E {QTY < 500} TN $73.00 $85.00 $79.00 $79.0035 Pavement Patching TN $105.00 $90.00 $110.00 $101.67 $125.00 $101.67

36 Reinf. Conc. Pipe 12-inch L.F. $35.00 $50.00 $39.00 $41.33 $13.10 3.2 $41.3337 Reinf. Conc. Pipe 18-inch L.F. $37.00 $60.00 $45.00 $47.33 $16.60 2.9 $47.3338 Reinf. Conc. Pipe 24-inch L.F. $72.00 $75.00 $65.00 $70.67 $23.10 3.1 $70.67

MINERAL AGGREGATES

ASPHALT CONCRETE PAVEMENT

CULVERTS AND PIPES


Unit Costs Backup #1


ROADWAY EXCAVATION

X011084_3538 6 of 24Unit Costs Backup #1

December 2002




39 Reinf. Conc. Pipe 30-inch L.F. $90.00 $100.00 $102.00 $97.33 $42.50 2.3 $97.3340 Reinf. Conc. Pipe 36-inch L.F. $121.00 $110.00 $115.50 $50.20 2.3 $115.5041 Reinf. Conc. Pipe 42-inch L.F. $170.00 $150.00 $160.00 $67.25 2.4 $160.0042 Reinf. Conc. Pipe 48-inch L.F. $170.00 $170.00 $81.10 2.1 $170.0043 Reinf. Conc. Pipe 54-inch L.F. $108.00 2.1 $226.8044 Reinf. Conc. Pipe 60-inch L.F. $300.00 $300.00 $140.70 2.1 $300.0045 Reinf. Conc. Pipe 66-inch L.F.46 Reinf. Conc. Pipe 72-inch L.F. $181.25 $380.63

47 Corrugated Metal Pipe 12-inch L.F. $22.00 $22.00 $7.11 3.1 $22.0048 Corrugated Metal Pipe 18-inch L.F. $32.76 $32.76 $11.10 3.0 $32.7649 Corrugated Metal Pipe 24-inch L.F. $37.50 $37.50 $16.56 2.3 $37.5050 Corrugated Metal Pipe 30-inch L.F. $57.00 $65.00 $61.00 $20.80 2.9 $61.0051 Corrugated Metal Pipe 36-inch L.F. $75.00 $75.00 $25.63 2.9 $75.0052 Corrugated Metal Pipe 42-inch L.F. $30.13 2.7 $81.3553 Corrugated Metal Pipe 48-inch L.F. $89.00 $89.00 $34.51 2.6 $89.0054 Corrugated Metal Pipe 54-inch L.F. $103.80 $103.80 $48.85 2.1 $103.8055 Corrugated Metal Pipe 60-inch L.F. $140.00 $140.00 $52.00 2.7 $140.0056 Corrugated Metal Pipe 66-inch L.F. $265.00 $265.00 $77.72 3.4 $265.0057 Corrugated Metal Pipe 72-inch L.F. $300.00 $300.00 $80.50 3.7 $300.00

* 84" DIA. H.C.M.P. L.F. $340.00 factored from 72"* 96" DIA. H.C.M.P. L.F. $390.00 factored from 72"*108" DIA. H.C.M.P. L.F. $440.00 factored from 72"CORRUGATED METAL PIPE 144-INCH L.F. $580.00 factored from 72"

58 Corrugated Metal Pipe Arch 21"x 15" (Equiv. Dia 18") L.F. $12.90 3.0 $38.0759 Corrugated Metal Pipe Arch 28"x 20" (Equiv. Dia 24") L.F. $18.96 2.3 $42.9360 Corrugated Metal Pipe Arch 35"x 24" (Equiv. Dia 30") L.F. $23.80 2.9 $69.8061 Corrugated Metal Pipe Arch 42"x 29" (Equiv. Dia 36") L.F. $29.23 2.9 $85.5362 Corrugated Metal Pipe Arch 49"x 33" (Equiv. Dia 42") L.F. $34.33 2.7 $92.6963 Corrugated Metal Pipe Arch 57"x 38" (Equiv. Dia 48") L.F. $39.31 2.6 $101.3864 Corrugated Metal Pipe Arch 64"x 43" (Equiv. Dia 54") L.F. $54.25 2.1 $115.2765 Corrugated Metal Pipe Arch 71"x 47" (Equiv. Dia 60") L.F. $58.00 2.7 $156.1566 Corrugated Metal Pipe Arch 77"x 52" (Equiv. Dia 66") L.F. $84.32 3.4 $287.5067 Corrugated Metal Pipe Arch 83"x 57" (Equiv. Dia 72") L.F. $87.70 3.7 $326.83

68 Reinf. Conc. Box Culvert 72-inch x 24-inch L.F. $550.0069 Reinf. Conc. Box Culvert 72-inch x 36-inch L.F. $680.00

70 Concrete Inlet EA $970.00 $735.00 $1,000.00 $901.67 $901.6771 Catch Basin Type 1 EA $1,700.00 $785.00 $1,500.00 $1,328.33 $1,328.3372 Catch Basin Type 1L EA $1,950.00 $1,950.00 $1,950.0073 Catch Basin Type 2 48" EA $2,710.00 $3,129.00 $2,980.00 $2,939.67 $2,939.6774 Catch Basin Type 2 54" EA $3,670.00 $4,000.00 $3,650.00 $3,773.33 $3,773.33

75 Flow Control Structure, 48-inch EA $4,000.00 $4,000.00 $4,000.0076 Flow Control Structure, 54-inch EA $6,100.00 $6,100.00 $6,100.0077 Flow Control Structure, 72-inch EA $10,200.00 $10,200.00 $10,200.0078 Flow Control Structure, 96-inch EA $28,500.00 $26,000.00 $27,250.00 $27,250.0079 Flow Control Structure, 120-inch EA $40,000.00 $40,000.00 $40,000.0080 Pipe, Detention, Conc, 24-inch LF $150.00 $150.00 $150.0081 Pipe, Detention, Conc, 30-inch LF $270.00 $270.00 $270.0082 Pipe, Detention, Conc, 54-inch LF $600.00 $600.00 $600.0083 Pipe, Detention, Conc, 60-inch LF $750.00 $750.00 $750.0084 Flow Control (FROP-T) Device EA $840.00






December 2002




85 Erosion Control, Hydro-seeding {QTY < 1000} SF $3.00 $3.00 $3.00Erosion Control, Hydro-seeding {1000 <= QTY < 5000} SF $1.09 $0.65 $0.45 $0.73 $0.73Erosion Control, Hydro-seeding {QTY >= 5000} SF $0.12 $0.12 $0.12 $0.22 $0.12

86 Erosion Control, Matting, Jute SF $0.56 $1.20 $0.88 $0.8887 Erosion Control, Matting, Wood Excelsior SF $0.75 $0.80 $0.78 $0.7888 Fence, Temporary Silt Containment LF $8.50 $4.00 $11.00 $7.83 $7.8389 Erosion Control LS 5%

90 Topsoil CY $29.00 $27.00 $27.00 $27.67 $27.6791 Sodding {QTY < 1000} SF $1.50 $2.50 $2.00 $2.0092 Sodding {QTY >= 1000} SF $0.87 $1.40 $1.14 $1.1493 Seeded Lawn Installation {QTY < 10,000} SF $0.55 $0.60 $0.58 $0.58

Seeded Lawn Installation {QTY >= 10,000} SF $0.07 $0.04 $0.20 $0.10 $0.10

94 Curb, Cement Conc. LF $13.30 $18.00 $15.65 $15.6595 Curb and Gutter, Cement and Conc. LF $24.00 $14.60 $19.30 $19.3096 Curb, Extruded Asphalt Concrete LF $6.50 $6.50 $6.5097 Curb, Extruded Cement Concrete LF $8.30 $8.00 $8.15 $8.15

Asphalt Swale LF $20.00 Seattle 2001 unit cost

98 Chain Link Fence LF $13.50 $12.00 $12.75 $12.7599 Chain Link Gate 6 FT Wide EA $508.00 $450.00 $479.00 $479.00100 Chain Link Gate 12 FT Wide EA $600.00 $600.00 $600.00101 Chain Link Gate 14 FT Wide EA $615.00 $650.00 $632.50 $632.50102 Chain Link Gate 20 FT Wide EA $850.00 $1,500.00 $1,175.00 $1,175.00103 Remove & Reinstall Chain Link Fence LF $14.85 $14.85 $14.85

104 Sidewalk Cement Concrete {QTY < 500} SY $32.00 $34.50 $33.25 $33.25Sidewalk Cement Concrete {QTY >= 500} SY $20.00 $26.50 $23.25 $23.25

105 Curb Ramp, Cement Concrete EA $420.00 $430.00 $425.00 $425.00106 Driveway, Cement Concrete, 6-inch SY $35.00 $35.00 $35.00107 Driveway, Cement Concrete, 8-inch SY $38.00 $38.00 $38.00

Riparian Corridor SY $15.50 based on $75,000/acre

108 Traffic Control LS 3% $0.03109 Mobilization LS 8% $0.08110 Contingency LS 30% $0.30111 Engineering LS 35% $0.35112 Large Woody Debris EA $500.00 $800.00

MISCELLANEOUS ITEMS

OTHER ITEMS

LANDSCAPE ESTABLISHMENT

CURB AND GUTTER



EROSION CONTROL


December 2002

Attachment Unit Costs Backup #2

Unit Unit Prices Unit Unit Prices

CLEARING AND GRUBBING ACRE $3,225.00 SF $2.00

REMOVE AND REPLACE ROCKERY CY $150.00REMOVE CEM. CONC. SIDEWALK SY $15.75REMOVE PAVEMENT SY $20.00REMOVE CURB AND GUTTER LF $9.25REMOVE CULVERT LF $12.00REMOVE FENCE, WOODREMOVE FENCE, CHAIN LINKREMOVE PIPEREMOVE CATCH BASINREMOVE INLETREMOVE MANHOLEREMOVE SCRUBREMOVE SIGNREMOVE TREESAW ASPHALT CONCRETE FULL DEPTHSAW CEMENT CONCRETE, 2-INCH MIN.DEPTHSAW CEMENT CONCRETE, FULL DEPTHABANDON CATCH BASINABANDON INLETABANDON MANHOLEABANDON AND FILL PIPE

COMMON EXCAVATION {QTY >= 1000} CY $8.25 CY $30.00COMMON EXCAVATION {QTY < 1000}STRUCTURE EXCAVATIONCHANNEL EXCAVATION CY $19.10


ROADWAY EXCAVATION

King (12/6/1998) Seattle (2000)


Material


X011084_3538 9 of 24Unit Costs Backup Sheet #2

December 2002



King (12/6/1998) Seattle (2000)Material

CRUSHED SURFACE BASE COURSE TN $20.00 CY $30.00CRUSHED SURFACE TOP COURSE TN $20.00GRAVEL BORROW CY $19.00STREAM GRAVEL TN $27.00PIPE BEDDINGRIPRAP, LIGHT LOOSE TN $27.00 TN $55.00RIPRAP, 2 IN TO 6 IN QUARRY SPALLS TN $29.00QUARRY SPALLS TN $46.00CONTROLLED DENSITY FILL CY $95.00

PAVEMENT, CEM CONC WITH BASE SY $80.00PAVMT PATCH, CEM CONC CL 6.5 (1-1/2), HES CY $240.00PAVEMENT, ASPHALT CONCRETE CL A {QTY < 500} CY $105.00PAVEMENT, ASPHALT CONCRETE CL B {QTY < 500}PAVEMENT, ASPHALT CONCRETE CL E {QTY < 500}ASPHALT CONCRETE PAVEMENT PATCHING SY $22.00 CY $225.00ASPHALT TREATED BASE

* 12" DIA. H.D.P.P. LF $56.00* 18" DIA. H.D.P.P. LF $67.00* 24" DIA. H.D.P.P. LF $90.00

CLEANOUT, 8 IN EA $955.00

REINF. CONC. PIPE 12-INCH LF $40.00 LF $68.00REINF. CONC. PIPE 15-INCH LF $73.00REINF. CONC. PIPE 18-INCH LF $45.00 LF $99.00REINF. CONC. PIPE 21-INCH LF $127.00REINF. CONC. PIPE 24-INCH LF $55.00 LF $128.00REINF. CONC. PIPE 30-INCH LF $84.00 LF $134.00REINF. CONC. PIPE 36-INCH LF $97.00 LF $153.00

PIPES

PAVEMENT

MINERAL AGGREGATES


December 2002




REINF. CONC. PIPE 42-INCH LF $127.00 LF $195.00REINF. CONC. PIPE 48-INCH LF $150.00 LF $217.00REINF. CONC. PIPE 54-INCH LF $175.00 LF $353.00REINF. CONC. PIPE 60-INCH LF $215.00 LF $354.00REINF. CONC. PIPE 66-INCH REINF. CONC. PIPE 72-INCH LF $300.00* 84" DIA. R.C.P. LF $350.00* 96" DIA. R.C.P. LF $475.00*108" DIA. R.C.P. LF $615.00

CORRUGATED METAL PIPE 12-INCH LF $36.00CORRUGATED METAL PIPE 18-INCH LF $40.00CORRUGATED METAL PIPE 24-INCH LF $50.00CORRUGATED METAL PIPE 30-INCH LF $64.00CORRUGATED METAL PIPE 36-INCH LF $72.00CORRUGATED METAL PIPE 42-INCH LF $90.00CORRUGATED METAL PIPE 48-INCH LF $100.00CORRUGATED METAL PIPE 54-INCH LF $105.00CORRUGATED METAL PIPE 60-INCH LF $110.00CORRUGATED METAL PIPE 66-INCH CORRUGATED METAL PIPE 72-INCH LF $140.00* 84" DIA. H.C.M.P. LF $161.00* 96" DIA. H.C.M.P. LF $195.00*108" DIA. H.C.M.P. LF $250.00CORRUGATED METAL PIPE 144-INCH

CORRUGATED METAL PIPE ARCH 21"X 15" (EQUIV. DIA 18") CORRUGATED METAL PIPE ARCH 28"X 20" (EQUIV. DIA 24") CORRUGATED METAL PIPE ARCH 35"X 24" (EQUIV. DIA 30") CORRUGATED METAL PIPE ARCH 42"X 29" (EQUIV. DIA 36") CORRUGATED METAL PIPE ARCH 49"X 33" (EQUIV. DIA 42") CORRUGATED METAL PIPE ARCH 57"X 38" (EQUIV. DIA 48") CORRUGATED METAL PIPE ARCH 64"X 43" (EQUIV. DIA 54") CORRUGATED METAL PIPE ARCH 71"X 47" (EQUIV. DIA 60")

ARCH PIPES AND CULVERTS(added roughly 10 cents per inch diameter to the equivalent diameter cost)


December 2002




CORRUGATED METAL PIPE ARCH 77"X 52" (EQUIV. DIA 66") CORRUGATED METAL PIPE ARCH 83"X 57" (EQUIV. DIA 72")

REINF. CONC. BOX CULVERT 72-INCH X 24-INCHREINF. CONC. BOX CULVERT 72-INCH X 36-INCHREINF. CONC. BOX CULVERT CY $500.00

CONCRETE INLETCATCH BASIN TYPE 1 EA $1,200.00CATCH BASIN TYPE 1LCATCH BASIN TYPE 2 48" EA $3,400.00 EA $2,980.00CATCH BASIN TYPE 2 54" EA $4,000.00 EA $3,650.00CATCH BASIN TYPE 202 72" EA $7,000.00 EA $6,000.00CATCH TYPE 203 84" EA $8,000.00CATCH BASIN TYPE 204 96" EA $9,000.00 EA $15,500.00CATCH BASIN TYPE 205 120" EA $21,000.00CATCH BASIN TYPE 206 144" EA $24,000.00EXTRA DEPTH, ALL TYPES VF $400.00

FLOW CONTROL STRUCTURE, 48-INCH EA $4,000.00FLOW CONTROL STRUCTURE, 54-INCH EA $6,100.00FLOW CONTROL STRUCTURE, 72-INCH EA $10,200.00FLOW CONTROL STRUCTURE, 96-INCH EA $26,000.0096" FLOW CONTROLLER MANHOLE (<12 FT.) EA $23,000.0096" FLOW CONTROLLER MANHOLE (>12 FT.) EA $34,000.00FLOW CONTROL STRUCTURE, 120-INCH EA $40,000.00PIPE, DETENTION, CONC, 24-INCH LF $150.00PIPE, DETENTION, CONC, 30-INCH LF $270.00PIPE, DETENTION, CONC, 54-INCH LF $600.00PIPE, DETENTION, CONC, 60-INCH LF $750.00FLOW CONTROL (FROP-T) DEVICE EA $840.00





December 2002




EROSION CONTROL, HYDRO-SEEDING {QTY < 1000} ACRE $1,400.00EROSION CONTROL, HYDRO-SEEDING {1000 <= QTY < 5000}EROSION CONTROL, HYDRO-SEEDING {QTY >= 5000}EROSION CONTROL, MATTING, JUTE SF $1.20EROSION CONTROL, MATTING, WOOD EXCELSIORFENCE, TEMPORARY SILT CONTAINMENT LF $11.00

TOPSOIL CY $27.00 CY $35.00SODDING {QTY < 1000} SF $2.50SODDING {QTY >= 1000}SEEDED LAWN INSTALLATION {QTY < 10,000}SEEDED LAWN INSTALLATION {QTY >= 10,000}ROADSIDE PLANTING/LANDSCAPING SY $25.00TREE EA $135.00SHRUB EA $15.00BEDDING, SPECIAL CDF CY $300.00

CURB, CEMENT CONC. LF $18.00CURB AND GUTTER, CEMENT AND CONC.CURB, EXTRUDED ASPHALT CONCRETE LF $6.00 LF $6.50CURB, EXTRUDED CEMENT CONCRETE LF $8.00

LIVESTOCK CONTROL FENCE LF $10.00CHAIN LINK FENCE LF $14.00CHAIN LINK GATE 6 FT WIDECHAIN LINK GATE 12 FT WIDECHAIN LINK GATE 14 FT WIDECHAIN LINK GATE 20 FT WIDEREMOVE & REINSTALL CHAIN LINK FENCE

CURB AND GUTTER

LANDSCAPING

EROSION CONTROL



December 2002




SIDEWALK CEMENT CONCRETE {QTY < 500} SY $34.50SIDEWALK CEMENT CONCRETE {QTY >= 500}CURB RAMP, CEMENT CONCRETEDRIVEWAY, CEMENT CONCRETE, 6-INCHDRIVEWAY, CEMENT CONCRETE, 8-INCH

TRAFFIC CONTROLMOBILIZATION % of sum $0.07CONTINGENCYLARGE WOODY DEBRIS

ENGINEERINGROCK FACING SF $16.00STRUCTURAL CONCRETE CY $500.00CONCRETE CLASS A (INCLUDES FORMS AND REBAR) CY $1,600.00EMBANKMENT COMPACTION CY $2.00STRUCTURAL FILL (INCLUDING COMPACTION) CY $15.00ACCESS ROAD (15' WIDE, 6" GRAVEL DEPTH) LF $17.00GABIONS (WITH ROAD ACCESS) CY $175.00GABIONS (WITHOUT ROAD ACCESS) CY $275.00TRASH RACK EA $500.00REVEGETATION (RIPARIAN CORRIDOR) SY $15.75BIOENGINEERING BANK STABILIZATION LF $350.00FISH HABITAT STRUCTURE (ROOT WAD) EA $200.00

OTHER ITEMS



December 2002

Attachment Allen Projects Backup

TOTALUNIT UNIT CREW UNIT UNIT

DESCRIPTION QTY UNIT COST TOTAL HOURS RATE COST TOTAL COST COMMENTS

CORRUGATED METAL PIPE ARCH 5' span x 4' rise LF $115.00 Use 64"x43" cost from databaseCORRUGATED METAL PIPE ARCH 5.4' span x 4.1' rise LF $115.00 Use 64"x43" cost from databaseCORRUGATED METAL PIPE ARCH 5.5' span x 2.5' rise LF $110.00 Use 57"x38" cost from databaseCORRUGATED METAL PIPE ARCH 5.5' span x 4.5' rise LF $150.00 based on 64"x43" cost CORRUGATED METAL PIPE ARCH 5.5' span x 5' rise LF $160.00 Use 71"x47" cost CORRUGATED METAL PIPE ARCH 5.5' span x 5.5' rise LF $200.00 based on 71"x47" cost x 2 for 11' x 5.5' culvertsCORRUGATED METAL PIPE ARCH 6' span x 4.5' rise LF $190.00 based on 71"x47" cost from databaseCORRUGATED METAL PIPE ARCH 6' span x 5' rise LF $310.00 based on 71"x47" cost from databaseCORRUGATED METAL PIPE ARCH 6' span x 5.2' rise LF $320.00 based on 71"x47" cost from databaseCORRUGATED METAL PIPE ARCH 6' span x 5.5' rise LF $325.00 based on 77"x52" cost x 2 for 12' x 5.5' culvertsCORRUGATED METAL PIPE ARCH 6' span x 6.5' rise LF $350.00 based on 77"x52" cost x 2 for 13' x 5.5' culvertsMETAL PLATE ARCH 13' span x 8' rise LF $660.00 Use 83"x57" cost x 2

132" x 84" Box Culvert (12'x 7') 1 LF $1,550.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 $4.00 minimalExcavation 13.3 CY $0.00 $0.00 0.01 $350.00 $3.50 $46.67 $3.50 $46.67 1: 1 slope, 3' of coverImported Fill 0.6 CY $15.00 $8.33 0.05 $300.00 $15.00 $8.33 $30.00 $16.67 under structure onlyNative Fill 9.0 CY $0.00 $0.00 0.02 $400.00 $8.00 $72.00 $8.00 $72.00Waste 4.3 CY $0.00 $0.00 0.01 $500.00 $5.00 $21.67 $5.00 $21.67Box Culvert 1 LF $715.00 $715.00 1 $500.00 $500.00 $500.00 $1,215.00 $1,215.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 $50.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 $16.30 assume 50' longMisc Detail 1 LS $37.46 $37.46 0 $0.00 $69.30 $69.30 $106.77 $106.77 surf restoration, traffic control, etc

66" x 74.4" Box Culvert (use 6'x 6') 1 LF $860.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $2.00 $2.00 $2.00 $2.00 minimalExcavation 8.1 CY $0.00 $0.00 0.01 $350.00 $3.50 $28.52 $3.50 $28.52 1: 1 slope, 3' of coverImported Fill 0.4 CY $15.00 $6.67 0.05 $300.00 $15.00 $6.67 $30.00 $13.33 under structure onlyNative Fill 6.3 CY $0.00 $0.00 0.02 $400.00 $8.00 $50.67 $8.00 $50.67Waste 1.8 CY $0.00 $0.00 0.01 $500.00 $5.00 $9.07 $5.00 $9.07Box Culvert 1 LF $357.50 $357.50 0.6 $500.00 $300.00 $300.00 $657.50 $657.50 quote + markup & installationWing Walls 0.06 CY $200.00 $12.00 1 $300.00 $300.00 $18.00 $500.00 $30.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.07 CY $20.00 $1.48 0.1 $350.00 $35.00 $2.59 $55.00 $4.07 assume 50' longMisc Detail 1 LS $18.88 $18.88 0 $0.00 $41.75 $41.75 $60.63 $60.63 surf restoration, traffic control, etc

66" x 60" Box Culvert (use 6' x 5') 1 LF $800.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LF $0.00 $0.00 0 $0.00 $2.00 $2.00 $2.00 $2.00 minimalExcavation 7.3 CY $0.00 $0.00 0.01 $350.00 $3.50 $25.67 $3.50 $25.67 1: 1 slope, 3' of coverImported Fill 0.4 CY $15.00 $6.67 0.05 $300.00 $15.00 $6.67 $30.00 $13.33 under structure onlyNative Fill 5.8 CY $0.00 $0.00 0.02 $400.00 $8.00 $46.22 $8.00 $46.22Waste 1.6 CY $0.00 $0.00 0.01 $500.00 $5.00 $7.78 $5.00 $7.78Box Culvert 1 LF $330.00 $330.00 0.5 $500.00 $250.00 $250.00 $580.00 $580.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 $50.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 $16.30 assume 50' longMisc Detail 1 LS $18.13 $18.13 0 $0.00 $37.87 $37.87 $56.00 $56.00 surf restoration, traffic control, etc


MATERIAL LABOR/EQUIPMENT

Allen Projects BackupORDER OF MAGNITUDE COST OPINION


X011084_3538 15 of 24Allen Projects Backup

December 2002









60" x 48" Box Culvert (use 5' x 4') 1 LF $690.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LF $0.00 $0.00 0 $0.00 $2.00 $2.00 $2.00 $2.00 minimalExcavation 5.9 CY $0.00 $0.00 0.01 $350.00 $3.50 $20.74 $3.50 $20.74 1: 1 slope, 3' of cover


December 2002





Imported Fill 0.4 CY $15.00 $6.11 0.05 $300.00 $15.00 $6.11 $30.00 $12.22 under structure onlyNative Fill 4.8 CY $0.00 $0.00 0.02 $400.00 $8.00 $38.52 $8.00 $38.52Waste 1.1 CY $0.00 $0.00 0.01 $500.00 $5.00 $5.56 $5.00 $5.56Box Culvert 1 LF $297.00 $297.00 0.4 $500.00 $200.00 $200.00 $497.00 $497.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 $50.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 $16.30 assume 50' longMisc Detail 1 LS $16.45 $16.45 0 $0.00 $31.33 $31.33 $47.78 $47.78 surf restoration, traffic control, etc




December 2002

Attachment New Unit Costs 8-12-02



Fill for Pond Berms 1 TN $9.43 $9 0.005714 $400.00 $2.29 $2.29 $11.71 assume pitrun material & 1.75TN/CY

Remove concrete fish weir 1 EA $11,660.00Bypass Pumping-4" 2 DAY $62.70 $125 0 $0.00 $0.00 $0 $62.70 Blue BookGenerator 2 DAY $52.80 $106 0 $0.00 $0.00 $0 $52.80 Blue BookHoses 2 DAY $5.50 $11 0 $0.00 $0.00 $0 $5.50 Blue BookSandbags @ Cofferdam 1 LS $1,000.00 $1,000 4 $701.80 $2,807.20 $2,807 $3,807.20 AllowanceConcrete Removal 4 HR $0.00 $0 1 $398.05 $398.05 $1,592 $398.05Erosion Control Fencing 100 LF $0.00 $0 0.01 $277.15 $2.77 $277 $2.77Bank Restoration 1 LS $1,500.00 $1,500 0 $0.00 $0.00 $0 $1,500.00 AllowanceWetland Mitigation 1 LS $3,000.00 $3,000 0 $0.00 $0.00 $0 $3,000.00 AllowanceCreek Bedding 11 CY $0.00 $0 0.04 $398.05 $15.92 $177 $15.92 Replace 30' length, 10' wide, 1' depthMisc. Details and Materials 1 LS $0.00 $0 0 $0.00 $1,059.55 $1,060 $1,060

12" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE, JA 1 LF $320.0012" Dia Pipe 1 LF $5.08 $5.08 0.02 $350.00 $7.00 $7.00 $12.08 recent quote + installation in casing24" diameter casing Bore and Jack 1 LF $0.00 $0.00 0 $0.00 $0.00 $0.00 $300.00 RS Means 02445 300 0700Endseals 0.01 EA $500.00 $5.00 0 $0.00 $0.00 $0.00 $500.00 Assume average jacking legth is 200'Spacers 0.05 EA $100.00 $5.00 0 $0.00 $0.00 $0.00 $100.00 One per 20'Misc Detail 1 LS $0.75 $0.75 0 $0.00 $0.70 $0.70 $1.45 surf restoration, traffic control, etc



36" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE, JA 1 LF $540.0036" Dia Pipe 1 LF $39.68 $39.68 0.03 $350.00 $10.50 $10.50 $50.18 recent quote + installation in casing48" diameter casing Bore and Jack 1 LF $0.00 $0.00 0 $0.00 $0.00 $0.00 $465.00 RS Means 02445 300 0700Endseals 0.01 EA $1,100.00 $11.00 0 $0.00 $0.00 $0.00 $1,100.00 Assume average jacking legth is 200'Spacers 0.05 EA $375.00 $18.75 0 $0.00 $0.00 $0.00 $375.00 One per 20'Misc Detail 1 LS $3.47 $3.47 0 $0.00 $1.05 $1.05 $4.52 surf restoration, traffic control, etc

NEW UNIT COSTS 8-12-02ORDER OF MAGNITUDE COST OPINION


MINERAL AGGREGATES

PIPES


X011084_3583 18 of 24New Unit Costs 8-12-02

December 2002





42" DIA. SMOOTH INTERIOR WALL CORRUGATED POLYETHYLENE, JACK AND BORE CONSTRUCTION $890.0042" Dia Pipe 1 LF $46.29 $46.29 0.03 $350.00 $10.50 $10.50 $56.79 recent quote + installation in casing60" diameter casing Bore and Jack 1 LF $0.00 $0.00 0 $0.00 $0.00 $0.00 $800.00 Quote NW BoringEndseals 0.01 EA $1,300.00 $13.00 0 $0.00 $0.00 $0.00 $1,300.00 Assume average jacking legth is 200'Spacers 0.05 EA $375.00 $18.75 0 $0.00 $0.00 $0.00 $375.00 One per 20'Misc Detail 1 LS $3.90 $3.90 0 $0.00 $1.05 $1.05 $4.95 surf restoration, traffic control, etc

Jacking and Receiving Pits $35,530.00Shoring 3,042 SF $10.00 $30,420.00 0 $0.00 $0.00 $0.00 $10.00 Sheet pileDewatering 1 LF $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 minimalExcavation of Jacking Pit and Receiving Pit 280 CY $0.00 $0.00 0.01 $350.00 $3.50 $981.40 $3.50 Assume Jacking Pit 20' lengthx15' widex20' depth and receivingImported Fill 0.6 CY $15.00 $8.33 0.05 $300.00 $15.00 $8.33 $30.00 under structure onlyNative Fill 280 CY $0.00 $0.00 0.02 $400.00 $8.00 $2,243.20 $8.00Waste 4.3 CY $0.00 $0.00 0.01 $500.00 $5.00 $21.67 $5.00Misc Detail 1 LS $1,521.42 $1,521.42 0 $0.00 $325.86 $325.86 $1,847.28 surf restoration, traffic control, etc

CORRUGATED METAL PIPE ARCH 96" x 50.4" 1 LF $400.00 Based on 83"x57" cost from databaseCORRUGATED METAL PIPE ARCH 84" x 44.4" 1 LF $320.00 Based on 83"x57" cost from databaseCORRUGATED METAL PIPE ARCH 24" x 18" 1 LF $45.00 Use 28"x20" cost from databaseCORRUGATED METAL PIPE ARCH 103" x 71" 1 LF $500.00 Based on156"x96" cost from databaseCORRUGATED METAL PIPE ARCH 108" x 56" 1 LF $500.00 Based on156"x96" cost from database

REINF. CONC. BOX CULVERT 24-INCH X 24-INCH 1 LF $370.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 minimalExcavation 3.1 CY $0.00 $0.00 0.01 $350.00 $3.50 $10.89 $3.50 1: 1 slope, 3' of coverImported Fill 0.3 CY $15.00 $4.44 0.05 $300.00 $15.00 $4.44 $30.00 under structure onlyNative Fill 2.8 CY $0.00 $0.00 0.02 $400.00 $8.00 $22.22 $8.00Waste 0.3 CY $0.00 $0.00 0.01 $500.00 $5.00 $1.67 $5.00Box Culvert (2x2) 1 LF $99.00 $99.00 0.25 $500.00 $125.00 $125.00 $224.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 assume 50' longMisc Detail 1 LS $6.47 $6.47 0 $0.00 $20.86 $20.86 $27.33 surf restoration, traffic control, etc

REINF. CONC. BOX CULVERT 36-INCH X 30-INCH 1 LF $430.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 minimalExcavation 3.9 CY $0.00 $0.00 0.01 $350.00 $3.50 $13.48 $3.50 1: 1 slope, 3' of coverImported Fill 0.3 CY $15.00 $5.00 0.05 $300.00 $15.00 $5.00 $30.00 under structure onlyNative Fill 3.3 CY $0.00 $0.00 0.02 $400.00 $8.00 $26.67 $8.00Waste 0.5 CY $0.00 $0.00 0.01 $500.00 $5.00 $2.59 $5.00Box Culvert 1 LF $121.00 $121.00 0.3 $500.00 $150.00 $150.00 $271.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 assume 50' longMisc Detail 1 LS $7.60 $7.60 0 $0.00 $24.21 $24.21 $31.81 surf restoration, traffic control, etc

ARCH PIPE AND CULVERTS



December 2002






REINF. CONC. BOX CULVERT 42-INCH X 30-INCH (Duplicate of Above)



REINF. CONC. BOX CULVERT 24-INCH X 24-INCH (Duplicate of Above)

30" x 24" Box Culvert 1 LF $380.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 minimalExcavation 3.1 CY $0.00 $0.00 0.01 $350.00 $3.50 $10.89 $3.50 1: 1 slope, 3' of coverImported Fill 0.3 CY $15.00 $4.44 0.05 $300.00 $15.00 $4.44 $30.00 under structure onlyNative Fill 2.8 CY $0.00 $0.00 0.02 $400.00 $8.00 $22.22 $8.00Waste 0.3 CY $0.00 $0.00 0.01 $500.00 $5.00 $1.67 $5.00


December 2002





Box Culvert 1 LF $110.00 $110.00 0.25 $500.00 $125.00 $125.00 $235.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 assume 50' longMisc Detail 1 LS $7.02 $7.02 0 $0.00 $20.86 $20.86 $27.88 surf restoration, traffic control, etc

40" x 36" Box Culvert 1 LF $560.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 minimalExcavation 4.3 CY $0.00 $0.00 0.01 $350.00 $3.50 $15.17 $3.50 1: 1 slope, 3' of coverImported Fill 0.4 CY $15.00 $5.28 0.05 $300.00 $15.00 $5.28 $30.00 under structure onlyNative Fill 3.8 CY $0.00 $0.00 0.02 $400.00 $8.00 $30.00 $8.00Waste 0.6 CY $0.00 $0.00 0.01 $500.00 $5.00 $2.92 $5.00Box Culvert 1 LF $220.00 $220.00 0.35 $500.00 $175.00 $175.00 $395.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 assume 50' longMisc Detail 1 LS $12.56 $12.56 0 $0.00 $27.27 $27.27 $39.83 surf restoration, traffic control, etc



72" x 48" Box Culvert 1 LF $870.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 minimalExcavation 6.5 CY $0.00 $0.00 0.01 $350.00 $3.50 $22.81 $3.50 1: 1 slope, 3' of coverImported Fill 0.4 CY $15.00 $6.67 0.05 $300.00 $15.00 $6.67 $30.00 under structure onlyNative Fill 5.2 CY $0.00 $0.00 0.02 $400.00 $8.00 $41.78 $8.00Waste 1.3 CY $0.00 $0.00 0.01 $500.00 $5.00 $6.48 $5.00


December 2002





Box Culvert 1 LF $275.00 $275.00 0.75 $500.00 $375.00 $375.00 $650.00 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 assume 50' longMisc Detail 1 LS $15.38 $15.38 0 $0.00 $49.71 $49.71 $65.09 surf restoration, traffic control, etc

CB 4 PIECE EXPANSION RING 20" TO 26" DIAMETER $225.00 RS Means 02630 200 3200CB 4 PIECE EXPANSION RING 30" TO 36" DIAMETER $275.00 RS Means 02630 200 3300

2' X 2' GRATED COVER $60.00 Use $15/sf for small quantity

REMOVE & REINSTALL WOOD FENCE $19.00 Tacoma Bid Tab

CATCH BASIN AND INLETS

FENCE AND GATES


December 2002

Attachment New Unit Costs 9-6-02



CORRUGATED METAL PIPE ARCH 168" x 56.4" 1 LF $700.00 Based on 83"x57" cost from databaseCORRUGATED METAL PIPE ARCH 96" x 50.4" 1 LF $400.00 Based on 83"x57" cost from databaseCORRUGATED METAL PIPE ARCH 24" x 18" 1 LF $45.00 Use 28"x20" cost from database

REINF. CONC. BOX CULVERT 36-INCH X 24-INCH 1 LF $410.00Shoring 0 SF $0.00 $0.00 0 $0.00 $0.00 $0.00 $0.00 $0.00 not required, assume sloped excavationDewatering 1 LS $0.00 $0.00 0 $0.00 $4.00 $4.00 $4.00 $4.00 minimalExcavation 3.6 CY $0.00 $0.00 0.01 $350.00 $3.50 $12.44 $3.50 $12.44 1: 1 slope, 3' of coverImported Fill 0.3 CY $15.00 $5.00 0.05 $300.00 $15.00 $5.00 $30.00 $10.00 under structure onlyNative Fill 3.1 CY $0.00 $0.00 0.02 $400.00 $8.00 $24.89 $8.00 $24.89Waste 0.4 CY $0.00 $0.00 0.01 $500.00 $5.00 $2.22 $5.00 $2.22Box Culvert 1 LF $104.50 $104.50 0.3 $500.00 $150.00 $150.00 $254.50 $254.50 quote + markup & installationWing Walls 0.10 CY $200.00 $20.00 1 $300.00 $300.00 $30.00 $500.00 $50.00 concrete 10' x 7' each - 5cy @ $500/50'Energy Dissipator 0.30 CY $20.00 $5.93 0.1 $350.00 $35.00 $10.37 $55.00 $16.30 assume 50' longMisc Detail 1 LS $6.77 $6.77 0 $0.00 $23.89 $23.89 $30.66 $30.66 surf restoration, traffic control, etc






ARCH PIPE AND CULVERTS


December 2002

Attachment Culvert Cost Estimation Method

Concrete Box Culvert Cost Estimation Method

Since many of the re-designed culvert sizes required within the Quilceda DNR were not in the Unit Cost Sheet, an equation was derived to estimate additional culvert costs. The data for concrete culverts was taken from the "unit prices" sheet of DNR Unit Prices.

y = 15.669x + 363.25R2 = 0.9171

$-

$200

$400

$600

$800

$1,000

$1,200

$1,400

$1,600

$1,800

0.00 10.00 20.00 30.00 40.00 50.00 60.00 70.00 80.00 90.00

Flow Area of Pipe (ft2)

Cos

t per

LF

($/ft

)

Span (in)

Rise (in)

Area (sq ft)

Cost(dollars)

24 24 4.00 370$ 30 24 5.00 380$ 36 24 6.00 410$ 36 30 7.50 430$ 42 30 8.75 510$ 36 36 9.00 440$ 40 36 10.00 560$ 42 36 10.50 530$ 72 24 12.00 550$ 48 36 12.00 560$ 54 36 13.50 640$ 54 42 15.75 490$ 72 36 18.00 680$ 72 36 18.00 850$ 60 48 20.00 690$ 66 48 22.00 740$ 57 60 23.75 770$ 72 48 24.00 870$ 66 60 27.50 800$ 66 74.4 34.10 860$ 66 78 35.75 800$

132 84 77.00 1,550$

Drainage Needs Reports Protocols

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