Pier Watershed Alternatives Feasibility Study

Pier Watershed Alternatives Feasibility Study

FINAL October 2014

1561 E. Orangethorpe Avenue, Suite 240 Fullerton, California 92831 TEL (714) 526-7500 | FAX (714) 526-7004 www.cwecorp.com

Pier Watershed Alternatives Feasibility Study

FINAL

Prepared for:

City of Santa Monica

Civil Engineering Division 1437 4th Street, Suite 300

Santa Monica, California 90401 TEL (310) 458-8411

Prepared by:

1561 E. Orangethorpe Avenue, Suite 240

Fullerton, California, 92831

TEL (714) 526-7500 | FAX (714) 526-7004 | www.cwecorp.com

October 30, 2014

City of Santa Monica Civil Engineering Division Pier Watershed Alternatives Feasibility Study

Table of Contents

1. PROJECT BACKGROUND ..................................................................................................... 1

2. EXISTING CONDITIONS ..................................................................................................... 3

2.1 TOPOGRAPHY ........................................................................................................................... 3 2.2 DRAINAGE ............................................................................................................................... 3 2.3 LAND USE ............................................................................................................................... 4 2.4 SOIL CONDITIONS ..................................................................................................................... 6

2.4.1 Geology and Subsurface Conditions .................................................................................. 6 2.4.2 Groundwater .................................................................................................................. 7 2.4.3 Faulting and Seismicity .................................................................................................... 8 2.4.4 Geotechnical Conclusions................................................................................................. 9

3. HYDROLOGIC CONDITIONS ............................................................................................. 10

3.1 DESIGN RAINFALL EVENT .......................................................................................................... 10 3.2 HYDROLOGIC CHARACTERISTICS AND TIME OF CONCENTRATION .......................................................... 10 3.3 HYDROLOGIC RESPONSE TO DESIGN RAINFALL EVENT....................................................................... 12 3.4 EXISTING WATER QUALITY IMPROVEMENTS ................................................................................... 14

4. WATER QUALITY IMPROVEMENT ALTERNATIVES ............................................................ 16

4.1 ALTERNATIVE 1 - SANITARY SEWER DIVERSION .............................................................................. 16 4.1.1 Project Description ........................................................................................................ 16 4.1.2 Potential Barriers .......................................................................................................... 16 4.1.3 Cost Estimate ............................................................................................................... 17

4.2 ALTERNATIVE 2 - SANITARY SEWER DIVERSION WITH SMURRF ......................................................... 17 4.2.1 Project Description ........................................................................................................ 17 4.2.2 Potential Barriers .......................................................................................................... 18 4.2.3 Cost Estimate ............................................................................................................... 19

4.3 ALTERNATIVE 3 - SMURRF SUPPLEMENTAL FLOWS ......................................................................... 20 4.3.1 Project Description ........................................................................................................ 20 4.3.2 Potential Barriers .......................................................................................................... 21 4.3.3 Cost Estimate ............................................................................................................... 21

4.4 ALTERNATIVE 4 - LOCAL INFILTRATION SYSTEM WITH SMURRF ......................................................... 22 4.4.1 Project Description ........................................................................................................ 22 4.4.2 Potential Barriers .......................................................................................................... 22 4.4.3 Cost Estimate ............................................................................................................... 23

4.5 ALTERNATIVE 5 - DIVERSION PLUS LOCAL INFILTRATION SYSTEM WITH SMURRF ................................... 24 4.5.1 Project Description ........................................................................................................ 24 4.5.2 Potential Barriers .......................................................................................................... 24 4.5.3 Cost Estimate ............................................................................................................... 24

5. COST BENEFIT ANALYSIS ................................................................................................. 26

6. GLOBAL CHANGES............................................................................................................. 27

7. REFERENCES ..................................................................................................................... 28

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Appendices Appendix A 2008 Storm Drain Improvement Project Geotechnical Report Appendix B Alternative 1 - Sanitary Sewer Diversion Schematic Drawing Appendix C Alternative 2 - Sanitary Sewer Diversion with SMURRF Schematic Drawing Appendix D Alternative 3 - SMURRF Supplemental Flows Schematic Drawing Appendix E Alternative 4 - Local Infiltration System with SMURRF Schematic Drawing Appendix F Alternative 5 - Diversion plus Local Infiltration with SMURRF Schematic Drawing

List of Figures Figure 1-1 Pier Watershed within the City of Santa Monica ................................................................... 1 Figure 2-1 Existing Topography .......................................................................................................... 3 Figure 2-2 Existing Drainage ............................................................................................................... 4 Figure 2-3 Existing Land Use .............................................................................................................. 5 Figure 2-4 Los Angeles County Hydrology Manual Soil Types ................................................................ 6 Figure 2-5 Borings from 2008 Storm Drain Improvement Project Geotechnical Report ............................ 7 Figure 2-6 Groundwater Investigation Locations .................................................................................. 8 Figure 3-1 Monthly Precipitation and Temperature of Santa Monica Pier .............................................. 10 Figure 3-2 Subarea and Flow Directions ............................................................................................ 11 Figure 3-3 Existing Water Quality Improvements ............................................................................... 15

List of Tables Table 2-1 Land Use ............................................................................................................................ 5 Table 3-1 Hydrologic Characteristics of Watershed Subareas .............................................................. 12 Table 3-2 Hydrologic Analysis of the 85th Percentile, 24-Hour Rainfall Event ........................................ 13 Table 3-4 Summary of Hydrologic Analysis ........................................................................................ 15 Table 4-1 Alternative 1 Cost Estimate ................................................................................................ 17 Table 4-2 Alternative 2A Cost Estimate .............................................................................................. 19 Table 4-3 Alternative 2B Cost Estimate .............................................................................................. 20 Table 4-3 Alternative 3 Cost Estimate ................................................................................................ 21 Table 4-4 Alternative 4 Cost Estimate ................................................................................................ 23 Table 4-5 Alternative 5 Cost Estimate ................................................................................................ 25 Table 5-1 Cost Benefit Analysis Matrix ............................................................................................... 26

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Acronyms BMP Best Management Practice CBC California Building Code EWMP Enhanced Watershed Management Program GIS Geographic Information System HDPE High Density Polyethylene LACDPW Los Angeles County Department of Public Works MCE Maximum Considered Earthquake MGD Million Gallons per Day MODRAT Modified Rational Method MS4 Municipal Separate Storm Sewer System MSL Mean Sea Level NCDC National Climatic Data Center NCEER National Center for Earthquake Engineering Research NETR Nationwide Environmental Title Research O&M Operation and Maintenance OSHA Occupational Safety and Health Administration PGA Peak Ground Acceleration RCP Reinforced Concrete Pipe SCADA Supervisory Control and Data Acquisition SMURRF Santa Monica Urban Runoff Recycling Facility TMDL Total Maximum Daily Load VCP Vitrified Clay Pipe WMS Watershed Modeling System

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1. Project Background CWE was retained by the City of Santa Monica to develop alternatives in addressing dry-weather runoff and runoff generated by the 85th percentile, 24-hour storm event within the Pier Watershed. The City of Santa Monica is currently developing an Enhanced Watershed Management Program (EWMP) with the Santa Monica Bay Jurisdictional Group 2 and 3 EWMP Group in response to the requirements established in the 2012 Municipal Separate Storm Sewer System (MS4) Permit. Part VI.C.1.g of the MS4 Permit encourages groups to collaborate on multi-benefit regional projects that wherever feasible retain non-stormwater runoff and stormwater runoff from the 85th percentile, 24-hour storm event for areas tributary to the project. For areas that implement regional EWMP projects, the area tributary to the project is considered in compliance with all water quality objectives. The City of Santa Monica is one of the responsible parties in addressing the Santa Monica Bay Beaches Bacteria Total Maximum Daily Load (TMDL). The Pier Watershed, illustrated in Figure 1-1, is a 106-acre watershed tributary to the Santa Monica Bay Beaches and is currently experiencing exceedances in the bacteria water quality objectives identified in the TMDL. The City has completed several improvements within the Pier Watershed to reduce the bacterial loads measured in beach monitoring. These improvements made a remarkable progress starting in 2010; however the bacterial loads have increased again to the pre-2010 levels with no apparent change within the watershed. By implementing a project designed to retain all non-stormwater runoff and runoff generated by the 85th percentile, 24-hour storm event the Pier Watershed would be considered in compliance based on the goals of the EWMP.

Figure 1-1 Pier Watershed within the City of Santa Monica

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The Pier Watershed outlets along the coast in close proximity to the Santa Monica Urban Runoff Recycling Facility (SMURRF), as well as the Moss Avenue Pump Station, a sanitary sewer lift station upstream of the Hyperion Treatment Plant. These facilities represent opportunities for addressing stormwater and providing solutions. The following five alternatives are expanded within this report to assess the feasibility of implementing a regional EWMP project to retain runoff generated in the Pier Watershed:

1. Sanitary sewer diversion; 2. Sanitary sewer diversion with SMURRF; 3. SMURRF supplemental flows; 4. Local infiltration system; and 5. Combination of the above alternatives.

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2. Existing Conditions In order to determine the feasibility of a project within the Pier Watershed that would address the 85th percentile, 24-hour storm event, existing conditions must be evaluated to identify the site constraints. The existing topography, drainage, land use, and soil conditions are identified within this section. 2.1 Topography As illustrated in Figure 2-1, Pier Watershed topography slopes from the north to south. The highest elevation within the Pier Watershed is 104 feet above mean sea level (MSL), which is located in the north of the watershed near Wilshire Boulevard and 4th Street. The Pier Watershed has a low elevation of 18 feet above MSL near the sand, south west of Appian Way. There is a drop off of about fifty feet between Ocean Avenue and Palisades Beach Road parallel to the beachfront. With the exception of the drop off, the watershed has a relatively mild slope.

Figure 2-1 Existing Topography

2.2 Drainage Currently the drainage within the Pier Watershed is collected through an existing stormwater conveyance system and eventually discharges into the Santa Monica Bay through a sixty inch High Density Polyethylene (HDPE) located beneath the pier. As illustrated in Figure 2-2, a majority of the

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watersheds’ drainage is collected in storm drains located along 3rd Street, Santa Monica Boulevard, and Broadway. These storm drains confluence near Ocean Avenue and Broadway and route the runoff north within Colorado Avenue and confluence with the storm drain in Colorado Avenue. Runoff flowing south along Pacific Coast Highway and from Palisades Beach Road are collected along the existing storm drain on Colorado Avenue. All the collected runoff, flows towards the outfall below the pier. Some of the runoff is diverted to the SMURRF located on Moss Avenue and Appian Way and additional runoff is diverted to the sanitary sewer downstream of the SMURRF.

Figure 2-2 Existing Drainage

2.3 Land Use The land use within the Pier Watershed defined by the County of Los Angeles Department of Public Works (LACDPW) is illustrated in Figure 2-3 and summarized in Table 2-1. The watershed has been urbanized since before 1952 based on Historical Aerials provided by Nationwide Environmental Title Research (NETR), LLC. In 1952 the Pier Watershed was made up of mostly residential properties and between 1952 and 1972 the area started to became more commercialized. The imagery shows that the area became more commercialized over time, leading to today where the watershed is almost 75 percent commercial. The table also indicates the percent impervious area associated with the land use type. The landuses noted below are based on the LACDPW Geographic Information System (GIS) land uses.

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Figure 2-3 Existing Land Use

Table 2-1 Land Use

Land Use Land Use Category

% Impervious

Area (acres)

% of Watershed

Attended Pay Public Parking Facilities Commercial 91 13.3 12.5 Beach Parks Open 10 5.6 5.3 Developed Local Parks and Recreation Open 10 10.8 10.2 Freeways and Major Roads Other Urban 91 3.2 3.0 High-Rise Apartments and Condominiums

Multi-Family Residential 90 4.6 4.3

High-Rise Major Office Use Commercial 91 3.1 2.9 Hotels and Motels Commercial 96 5.4 5.1 Low- and Medium-Rise Major Office Use Commercial 91 12.3 11.6 Older Strip Development Commercial 97 32.6 30.7 Regional Shopping Center Commercial 95 12.2 11.4 Vacant Undifferentiated Open 1 3.3 3.1

Total: 106.4 100

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2.4 Soil Conditions Based on the Los Angeles County Hydrology Manual (LACDPW, 2006), the Pier Watershed contains soil types 013 (Ramona Loam) and 016 (Yolo Loam). As illustrated in Figure 2-4, the primary soil type is 013 within the watershed.

Figure 2-4 Los Angeles County Hydrology Manual Soil Types

In 2009 a diversion structure was constructed and storm drain improvements occurred at the Pier Watershed outlet below the Santa Monica Pier. During the design phase of the project a geotechnical investigation was conducted along the beach on the east side of the pier and in the parking lot on the west side (Ninyo & Moore, 2008). One of the alternatives evaluated in this report includes an infiltration Best Management Practice (BMP), which would be located within the beach, adjacent to the pier. The information from the 2008 geotechnical report is summarized in this section. 2.4.1 Geology and Subsurface Conditions The potential project site is located in the western portion of the Los Angeles Basin, situated between the Peninsular Ranges and Transverse Ranges geomorphic provinces of Southern California (Ninyo & Moore, 2008). The Los Angeles Basin has been divided into four structural blocks, which are generally bounded by prominent fault systems: the Northwestern Block, the Southwestern Block, the Central Block, and the Northeastern Block (Ninyo & Moore, 2008). The potential project site is located in the Southwestern Block, which is generally bounded by the Newport-Inglewood fault along the east and the Pacific

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Coastline along the west. The potential site is located along the relatively narrow strip of beach deposits that parallel the coastline. Elevated coastal bluffs, as discussed in Section 2.1, border the beach deposits and expose older alluvial sediments and Pleistocene age marine deposits (Ninyo & Moore, 2008). Beach deposits were encountered in the exploratory borings to the depths explored of up to approximately 31.5 feet. At the boring locations, demonstrated in Figure 2-5, the beach deposits were comprised of very loose to very dense sand, and sand with silt. In general, the upper approximately 5 to 10 feet of beach sand ranged from loose to medium dense. The materials below approximately 5 to 10 feet ranged from medium dense to very dense. Scattered lenses of dark gray to black sand deposits with an odor of decomposing organic material was also observed. Additional information discovered during the exploratory borings is presented in the following sections and detailed boring logs can be found in Appendix A.

Figure 2-5 Borings from 2008 Storm Drain Improvement Project Geotechnical Report

2.4.2 Groundwater Groundwater was encountered at the four exploratory borings from 2008 at depths varying from 3.5 feet to 9 feet below the ground surface as demonstrated in Figure 2-5. The groundwater depths generally correspond to elevations ranging from approximately 3 to 6.5 feet above MSL. Variations in the level of groundwater will occur and are influenced by tidal fluctuations, rainfall, stormwater runoff, ground surface topography, subsurface stratification, groundwater pumping, and irrigation activities. The

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groundwater depths found in 2008 may not correspond to existing conditions because rainfall quantities are not consistent. In February 2014, the City conducted additional groundwater table depth investigations on the north and east side of the pier. The City was able to dig test pits to determine the depth at which the water table was intercepted. Figure 2-6 identifies the test sites that were located near the Santa Monica Pier as those are near the potential infiltration BMP. The groundwater table was found to be between 4 and 9 feet below the ground surface, similar to the findings in the 2008 Pier Storm Drain Improvements Geotechnical Report.

Figure 2-6 Groundwater Investigation Locations

2.4.3 Faulting and Seismicity The potential project site is not located within a State of California Earthquake Fault Zone (Ninyo & Moore, 2008). However, the site is located in a seismically active area as is the majority of Southern California, and the potential for strong ground motion in the project area is considered significant during the design life of the proposed project. The closest active fault is the Santa Monica fault located over a mile northeast of the potential project site. The Pier Storm Drain Improvements Geotechnical Report (2008) lists additional active faults that may affect the potential project site along with the maximum moment magnitude.

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The principal seismic hazards that may potentially impact the potential site are surface fault rupture, ground motion, liquefaction, and tsunamis. Additional information regarding these hazards is provided in this section. 2.4.4 Geotechnical Conclusions The following conclusions applicable to the current project work can be drawn from the 2008 Pier Storm Drain Improvements Geotechnical Report. Recommendations based on the 2008 report can be found in Appendix A.

The site is underlain by loose to very dense beach sand deposits. Groundwater is at relatively shallow depths of approximately 3.5 to 9 feet below the existing

ground surface. Variations in the depth to groundwater will occur due to tidal fluctuations, rainfall and other

environmental factors. The project design should consider groundwater levels reaching the ground surface periodically. Excavations for pipeline trenches and below grade structures in the beach sand deposits should

be feasible with heavy-duty earthmoving equipment. Excavations may also encounter historic foundation remnants or other obstructions associated

with the existing pier facilities. Construction dewatering should be anticipated for excavations on site. The clean sandy soils on site will be prone to caving in trench and structure excavations. On-site soils should be considered as Type C soils in accordance with Occupational Safety and

Health Administration (OSHA) soil classifications. Contractors should anticipate appropriate shoring systems for the on-site sand.

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3. Hydrologic Conditions This section summarizes the hydrologic analysis performed to evaluate the amount of runoff produced during the 85th percentile, 24-hour storm event from the Pier Watershed. Figure 3-1 illustrates the monthly precipitation and temperature based on National Climatic Data Center (NCDC) long-term (1981-2010) data at the Santa Monica Pier. Based on this data, the region has a mean annual rainfall of 12.69 inches.

Figure 3-1 Monthly Precipitation and Temperature of Santa Monica Pier

The hydrologic analysis is based on the watershed information provided by the City of Santa Monica. Field observations were not performed and only limited as-built records were evaluated to verify the watershed boundary and tributary information. Storm runoff from the watershed is captured in storm drains owned and operated by the City of Santa Monica and the County of Los Angeles. As illustrated in Figure 2-2, a portion of the runoff is conveyed to the SMURRF, promoting the use of surface runoff for non-potable purposes. 3.1 Design Rainfall Event Hydrologic studies within the County of Los Angeles are required to use the modified rational method (MODRAT) developed by LACDPW (LACDPW, 2006). For water quality considerations, the 85th percentile, 24-hour rainfall event, plus smaller events, needs to be retained to be considered a regional EWMP project, therefore the 85th percentile storm event was used for the hydrologic analysis. The watershed lies between the 85th percentile rainfall contour lines of 0.95 and 1.05 inches (LACDPW, 2004). A unique rainfall depth value of 1.0 inch was adopted for the analysis of the entire watershed. All volume calculations use the 24-hour unit hyetograph with the design rainfall depth to generate runoff hydrographs. 3.2 Hydrologic Characteristics and Time of Concentration The characteristics of the Pier Watershed subareas influence time of concentration (Tc) and flow rates. The most important factors include the subarea size, land use as a percentage of impervious area, soil type, and flow path length and slope. Business areas (e.g. shopping center and hotels) attribute to increased imperviousness in some of the subareas. Figure 2-1, Figure 2-3, and Figure 2-4 illustrate the topography, land use, and soil types of the Pier Watershed respectively.

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The percent imperviousness within each of the subareas, based on land use types, ranges between approximately 8 percent and 74 percent, resulting in an area-weighted average of 47 percent. The longest flow path for each subarea was determined and the length and slope were developed in Watershed Modeling System (WMS) based on the elevation contour data provided by the City of Santa Monica. Figure 3-2 illustrates the subareas, flow directions, and outlets used for the hydrologic analysis and Table 3-1 summarizes the hydrologic characteristics of each of the subareas. Consistent with MODRAT a minimum Tc of five minutes and a maximum of thirty minutes was utilized for this hydrologic analysis.

Figure 3-2 Subarea and Flow Directions

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Table 3-1 Hydrologic Characteristics of Watershed Subareas

Subarea Area (ac)

Land Use % Imp. Soil # Flow Path

Length (ft) Flow Path

Slope (ft/ft) Developed Coefficient

Tc (min)

1A 5.2 94 13 964 0.093 0.85 25 3A 4.8 96 13 1,013 0.014 0.87 30 5A 4.3 94 13 978 0.074 0.85 26 7A 6.3 96 13 995 0.009 0.87 30 8B 5.5 95 13 925 0.093 0.86 24 10B 6.2 93 13 995 0.013 0.84 30 13A 12.2 95 13 1,310 0.010 0.86 30 15A 1.7 96 13 363 0.060 0.87 14 16C 5.6 91 13 977 0.085 0.83 26 18C 6.7 94 13 1,042 0.010 0.85 30 20C 6.4 94 13 974 0.008 0.85 30 22C 6.3 96 13 985 0.005 0.87 30 23C 11.1 8 13 2,643 0.013 0.16 30 26A 2.6 29 13 363 0.00 0.33 30 27A 1.5 91 13 799 0.014 0.83 30 28A 2.4 37 13 943 0.041 0.40 30 30A 2.6 95 13 233 0.028 0.86 12 32A 2.0 87 13 572 0.021 0.80 24 34A 3.4 14 13 704 0.009 0.21 30 35D 2.4 31 13 517 0.003 0.35 30 37D 7.2 91 13 686 0.006 0.83 30

3.3 Hydrologic Response to Design Rainfall Event Runoff is dependent on the rainfall event and the subarea characteristics. The design of stormwater BMPs and capture facilities requires understanding both peak runoff and volumes resulting from the design rainfall event. Table 3-2 summarizes the overall hydrologic responses of the 85th percentile, 24-hour storm event for all of the subareas, reach confluences, and outlets within the Pier Watershed. Flow rates and volumes are provided in cubic feet per second (cfs) and acre-feet (ac-ft) respectively. Runoff from each subarea is routed through the storm drain system to the collection points as shown in Figure 3-2. The main storm drain line A with three lateral lines B, C and D drain the 106.4 acres of the Pier Watershed to its outlet 39AD downstream of the SMURRF located at 31A. The contributing area of this outlet includes the parking lot represented by Subarea 37D. The peak runoff at the outlet reaches 13.2 cfs during an 85th percentile rain event and drains approximately 4.16 acre-feet (approximately 1,355,000 gallons). Outlet 31A, located near the SMURRF, receives a total water volume of 3.55 acre-feet (1,158,000 gallons) during the design rainfall event. The values found through the hydrologic analysis provide information on the volumes and peak runoff rates generated within the Pier Watershed were used to determine the feasibility of alternatives for a regional EWMP project.

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Table 3-2 Hydrologic Analysis of the 85th Percentile, 24-Hour Rainfall Event

Model Element Element Type

Subarea Area (ac)

Subarea Peak Runoff

(cfs)

Total Area (ac)

Outlet Peak Runoff (cfs)

Total Volume (ac-ft)

1A Subarea 5.2 1.14 5.2 0.36 2A Subarea Outlet 5.2 1.14 0.36 3A Subarea 4.8 1.07 10 0.70 4A Subarea Outlet 10 2.21 0.70 5A Subarea 4.3 0.94 14.3 1.00 6A Subarea Outlet 14.3 3.15 1.00 7A Subarea 6.3 1.41 20.6 1.45 8B Subarea 5.5 1.22 5.5 0.39 9B Subarea Outlet 5.5 1.22 0.39 10B Subarea 6.2 1.34 11.7 0.81 11B Subarea Outlet 11.7 2.56 0.81 12AB Confluence 11.7 32.3 7.12 2.26 13A Subarea 12.2 2.70 44.5 3.12 14A Subarea Outlet 44.5 9.81 3.12 15A Subarea 1.7 0.50 46.2 3.24 16C Subarea 5.6 1.21 5.6 0.38 17C Subarea Outlet 5.6 1.21 0.38 18C Subarea 6.7 1.47 12.3 0.85 19C Subarea Outlet 12.3 2.68 0.85 20C Subarea 6.4 1.40 18.7 1.29 21C Subarea Outlet 18.7 4.08 1.29 22C Subarea 6.3 1.41 25.0 1.74 23C Subarea 11.1 0.47 36.1 1.89 24C Subarea Outlet 36.1 5.95 1.89 25AC Confluence 36.1 82.3 16.25 5.13 26A Subarea 2.6 0.22 84.9 5.20 27A Subarea 1.5 0.32 86.4 5.30 28A Subarea 2.4 0.24 88.8 5.38 29A Subarea Outlet 88.8 17.04 5.38 30A Subarea 2.6 0.68 91.4 5.56 31A Subarea Outlet 91.4 17.72 5.56 32A Subarea 2.0 0.41 93.4 5.69 33A Subarea Outlet 93.4 18.13 5.69 34A Subarea 3.4 0.19 96.8 5.75 35D Subarea 2.4 0.21 2.4 0.07 36D Subarea Outlet 2.4 0.21 0.07 37D Subarea 7.2 1.53 9.6 0.56 38D Subarea Outlet 9.6 1.75 0.56 39AD Conf. & End Outlet 9.6 106.4 20.06 6.31

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3.4 Existing Water Quality Improvements Variety of water quality improvements have occurred within the Pier Watershed as a result of Planning and Land Development Program, which requires new- and re-development projects to mitigate the runoff produced by a 0.75-inch rainfall event. The City of Santa Monica has tracked these projects and provided data so that the volume mitigated can be apportioned as already being mitigated. The volume mitigated by these projects can be subtracted from the volume produced by the watershed to determine a more accurate mitigation volume. Table 3-3 summarizes the mitigation projects within the Pier Watershed and Figure 3-3 illustrates the associated parcel(s). The mitigation volumes in italics below are not included in the total volume because they do not retain runoff, thus the volume of water is not reduced.

Table 3-3 Existing Water Quality Improvement Projects

Parcel # Address BMP Type Mitigation Volume

(ac-ft) (ft3) (gal) 4291015005 1422 2nd Street Infiltration-Pit (Rock) 0.0069 300 2,244 4291014004 1314 2nd Street Use-Cistern 0.0096 419 3,134 4291028004 1530 2nd Street Infiltration-Pit (Rock) 0.0184 800 5,984 4291012008 331 Santa Monica Blvd. Miscellaneous-In Lieu - - - 4291016020 214 Santa Monica Blvd Filtering-Non-Vortex 0.0207 900 6,732 4291002019 1217 2nd Street Infiltration-Pit (Rock) 0.0042 184 1,376 4291002018 1221 2nd Street Infiltration-Pit (Rock) 0.0038 165 1,234 4291016014 1447 2nd Street Infiltration-Pit (Rock) 0.0039 170 1,272 4291002021 202 Wilshire Boulevard Miscellaneous-In Lieu - - - 4291014019 1323 Ocean Avenue Infiltration-Pit (Rock) 0.0076 330 2,468 4290017911 1637 Appian Way Biofilter-Gutters 0.0161 700 5,236 4290012902 1685 Main Street Biofilter-No Gutters 0.0071 310 2,319 4291016902 1431 2nd Street Miscellaneous-In Lieu - - -

4290017901 & 4290017908-10 1637 Appian Way Biofilter-Gutters 0.0161 700 5,236

4290017903-05 1623 Appian Way Reuse-SMURRF 0.9940 43,300 323,884

4290015028 1700 Main Street Infiltration - Concrete Vault 0.1768 7,700 57,596

4290017015 1602 Ocean Avenue Infiltration-Pit (Rock) 0.0130 565 4,228 4291002902 1227 2nd Street Infiltration-Pit (Rock) 0.0038 165 1,234

4291030907 1543 Ocean Front Walk High Efficiency Biotreatment 0.0528 2,300 17,204

4291014026 1301 Ocean Avenue Infiltration Pit (Plastic Box Modules) 0.0406 1,770 13,240

4291028027 1515 Ocean Avenue Filtering-Non-Vortex 0.0430 1,875 14,025 4291028026 1540 2nd Street Filtering-Non-Vortex 0.0537 2,340 17,503 4291013006 1338 3rd Street Promenade Miscellaneous-In Lieu 0.0095 415 3,104

4291012012 1343 3rd Street Promenade Filtering - Downspout Insert 0.0036 157 1,174

4291002008 1242 3rd Street Promenade Permeable Paving 0.0023 100 748 Total: 1.294 56,383 421,746

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Figure 3-3 Existing Water Quality Improvements

Based on the existing water quality improvement projects that have been constructed within the Pier Watershed, 56,383 cubic-feet, or 1.29 acre-feet, can be subtracted from the total volume determined in the hydrologic analysis. Approximately 5.02 acre-feet of volume will require mitigation by one of the alternatives discussed in Section 4 so that the Pier Watershed is considered in compliance due to the implementation of a regional EWMP project. Table 3-4 summarizes the peak runoff in cfs, gallons per minute (gpm), and million gallons per day (MGD), along with the total volume in acre-feet, cubic feet, and gallons, for the entire system at the outlet based on the hydrologic analysis. Additionally, the volume mitigated due to existing water quality improvement projects is presented along with the total volume requiring mitigation.

Table 3-4 Summary of Hydrologic Analysis CFS GPM MGD

Peak Runoff 20.06 9,003 13 Acre-feet Cubic feet Gallons

Total Volume 6.31 274,864 2,055,980 Mitigation Volume 1.29 56,383 421,746 New Total Volume 5.02 218,481 1,634,234

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4. Water Quality Improvement Alternatives This report evaluates the feasibility of five water quality improvement project alternatives, one of which is a combination of the first four, in retaining all dry-weather runoff and the runoff produced by the 85th percentile, 24-hour storm event within the Pier Watershed, thus qualifying as a regional EWMP project and ensuring the Pier Watershed is in compliance with the MS4 Permit. The alternatives are as follows:

1. Sanitary sewer diversion; 2. Sanitary sewer diversion with SMURRF;

a. Holding tank located on north side of pier; b. Holding tank located on south side of pier;

3. SMURRF supplemental flows; 4. Local infiltration system with SMURRF; and 5. Diversion plus local infiltration with SMURRF (combination of the above alternatives).

A description of the alternatives is provided in this section and potential barriers to project implementation are identified. A generalized cost analysis of each alternative is also identified to better assess the various options. 4.1 Alternative 1 - Sanitary Sewer Diversion 4.1.1 Project Description The first alternative for the Pier Watershed involves diverting the runoff produced by the 85th percentile, 24-hour storm event directly to the sanitary sewer. The Moss Avenue Pump Station, which pumps sanitary sewage that eventually reaches the Hyperion Treatment Plant, is located in close proximity to the Santa Monica Pier. The Moss Avenue Pump Station is located adjacent to the SMURRF on Appian Way near Moss Avenue. The Hyperion Treatment Plant is located just over six miles south along the coast in the City of Los Angeles. A schematic drawing illustrating this alternative concept is provided in Appendix B. The Pier Watershed Storm Drain was improved in 2009 to include a low flow diversion which pumps dry-weather runoff through two force mains to a sanitary sewer manhole on Ocean Front Walk, upstream of the Moss Avenue Pump Station (City of Santa Monica, 2009). This diversion system would be modified to divert wet-weather runoff directly to the sewer system, connecting at the manhole the low flow diversion currently joins. The pipe downstream of the manhole would need to be upgraded to accommodate the wet-weather capacity. An additional pumping system with the 85th percentile, 24-hour peak flow rate would be required and an additional force main would be installed. The runoff would be routed through a baffle box or clarifier to encourage sediment settling and remove gross solids. Currently the Moss Avenue Pump Station has four large pumps and one smaller pump for standby (City of Santa Monica, 1999). Field testing of the pump station demonstrated that the four pumps have a combined capacity of 36.9 million gallons per day (MGD) and three pumps have a capacity of 22.6 MGD. It is recommended that the pump station operates with three pumps and one pump on stand-by (Eren, 2014a). Two force mains currently exist and only one is used. With the current demand, the Moss Avenue Pump Station is able to operate using only one pump; therefore the pump station has sufficient capacity to handle the 85th percentile, 24-hour storm event runoff from the Pier Watershed. 4.1.2 Potential Barriers Potential barriers to the implementation of this alternative are identified in this section so that all considerations are made apparent prior to deciding on the final alternative. One potential barrier would

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be the size of the existing 24-inch Vitrified Clay Pipe (VCP) sewer line. An analysis will be needed to determine if there is enough capacity to divert the peak 85th percentile, 24-hour flow. If there is not enough capacity, the 180 feet of VCP would be replaced with a larger pipe. 4.1.3 Cost Estimate The cost analysis was developed using various sources of information as well as the cost estimator’s best judgment. The construction cost entails various components of the project to be constructed. Similar project components have been completed in Los Angeles County and the bids for these projects served as one source of reference when evaluating costs. Standard engineering procedures were used to determine a cost estimate as noted in Table 4-1.

Table 4-1 Alternative 1 Cost Estimate

Item Description Quantity Cost* Engineering Design Plan (10% of Construction) LS $162,000 Permits and Specifications (25% of Design Plan) LS $41,000 Environmental Assessment LS $29,000

Subtotal: $232,000 Construction Support Construction Administration and Inspections (10%) LS $162,000

Subtotal: $162,000 Construction Mobilization LS $118,000 Soil Export 20 CY $2,000 Trenching and Backfill 400 CY $31,000 Diversion Upgrade (Pumping System) LS $761,000 Reinforced Concrete Pipe 420 LF $74,000 Trash Rack LS $34,000 Clarifier System LS $256,000 Connection to Sanitary Sewer** LS $12,000

Subtotal: $1,283,000 Contingency (25%) LS $322,000

Total: $1,999,000 * Project completion date of 2019. ** Cost of replacement VCP not included.

4.2 Alternative 2 - Sanitary Sewer Diversion with SMURRF 4.2.1 Project Description The second alternative for the Pier Watershed involves diverting the runoff produced by the 85th percentile, 24-hour storm event to the SMURRF and sanitary sewer. Runoff would first be diverted to a holding tank. From there the runoff would be routed to the SMURRF until the facility reaches capacity for the three days following the storm event and the excess flows would be diverted to the sanitary sewer. The Moss Avenue Pump Station, which pumps sanitary sewage that eventually reaches the Hyperion Treatment Plant, is located in close proximity to the Santa Monica Pier. The Moss Avenue Pump Station

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is located adjacent to the SMURRF on Appian Way near Moss Avenue, while the Hyperion Treatment Plant is located just over six miles south along the coast in the City of Los Angeles. The Pier Watershed Storm Drain was improved in 2009 to include a low flow diversion which pumps dry-weather runoff through two force mains to a sanitary sewer manhole on Ocean Front Walk, upstream of the Moss Avenue Pump Station (City of Santa Monica, 2009). This diversion system would be modified to divert wet-weather runoff to a holding tank located beneath the parcel north of the City Yard on the north side of the pier (Alternative 2A). As an alternative, the holding tank could be placed on the south side of the Pier parallel to the Pier Watershed storm drain (Alternative 2B). Schematic drawings illustrating these alternative concepts are presented in Appendix C. The diversion to the holding tank would be facilitated through gravity to reduce the cost of the system. The holding tank would provide treatment, through a system such as baffle walls, to encourage sediment settling and remove gross solids so that the runoff can be transported to SMURRF and the sanitary sewer. The holding tank would require a volume of approximately 5.02 acre-feet based on the total mitigation volume determined in Section 3.4. Runoff would first be routed to SMURRF through a pumping system, up to 50,000 gallons per day (0.15 acre-feet) for each of the three days based on current needs and can be changed for the maximum design usage at SMURRF, until the facility reaches its capacity (City of Santa Monica, 2014b). For alternative 2A, additional runoff would be pumped to the existing sanitary sewer manhole located adjacent to the proposed holding tank along Ocean Front Walk. These flows would join the existing 60-inch sanitary sewer Reinforced Concrete Pipe (RCP) that travels southeast on Appian Way to the Moss Avenue Pump Station. Alternatively, the diversion to the sanitary sewer could be constructed so that the flows join the 24-inch VCP on Appian Way or abandoned sewer lines parallel to the 60-inch RCP. For alternative 2B, additional runoff will be pumped to the sanitary sewer manhole discussed in Section 4.1, that the Pier Watershed storm drain uses under dry-weather conditions. As discussed in Section 4.1.1, with the current demand, the Moss Avenue Pump Station is able to operate using only one pump; therefore the pump station has sufficient capacity to handle the 85th percentile, 24-hour storm event runoff from the Pier Watershed. Additionally, the holding tank would allow the runoff to be detained until the sanitary sewer demand is low, often in the middle of the night, to ensure the system has enough capacity. The system would include use of Supervisory Control and Data Acquisition (SCADA) system to enhance the performance of the system with logic built-in to divert the runoff amongst the various uses. 4.2.2 Potential Barriers Potential barriers to the implementation of this alternative are identified in this section so that all considerations are made apparent prior to deciding on the best alternative. One potential barrier would be the location of existing subsurface utilities. The routing of the diversion piping may have to be modified to avoid existing utilities and the cost associated with relocating them. During preliminary research, discrepancies were found regarding the location of the manhole this system could connect to along the 60-inch RCP under Alternative 2A. Additional verification is recommended and if the manhole identified is actually connected to the adjacent 24-inch sanitary sewer line then some modifications may be required. Based on the groundwater table depths identified in the field investigation performed by the City, illustrated in Figure 2-6, the groundwater may present problems and require additional construction costs. Additional information will be needed by the designer to ensure the system is structurally sound and no geotechnical hazards would arise from construction. For both Alternative 2A and 2B, the amount of available space may present some problems. It may be necessary to utilize deep holding tanks to minimize the footprint of the system.

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4.2.3 Cost Estimate The cost analysis was developed using various sources of information as well as the cost estimator’s best judgment. The construction cost entails various components of the project to be constructed. Similar project components have been completed in Los Angeles County and the bids for these projects served as one source of reference when evaluating costs. Standard engineering procedures were used to determine a cost estimate for Alternative 2A as noted in Table 4-2 and Alternative 2B as noted in Table 4-3.

Table 4-2 Alternative 2A Cost Estimate



Subtotal: $515,000 Construction Mobilization LS $375,000 Excavation 18,500 CY $129,000 Soil Export 7,400 CY $215,000 Trenching and Backfill 2,500 CY $189,000 Diversion Upgrade (Gravity) LS $54,000 Reinforced Concrete Pipe 1,800 LF $314,000 Trash Rack LS $34,000 Holding Tank LS $2,736,000 Connection to Sanitary Sewer LS $12,000 Connection to SMURRF LS $12,000 SCADA Equipment LS $47,000

Subtotal: $4,112,000 Contingency (25%) LS $1,029,000

Total: $6,329,000 * Project completion date of 2019.

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Table 4-3 Alternative 2B Cost Estimate



Subtotal: $433,000 Construction Mobilization LS $316,000 Excavation 10,000 CY $70,000 Soil Export 1,900 CY $56,000 Trenching and Backfill 500 CY $39,000 Diversion Upgrade (Gravity) LS $54,000 Reinforced Concrete Pipe 500 LF $87,000 Trash Rack LS $34,000 Holding Tank LS $2,736,000 Connection to Sanitary Sewer LS $12,000 Connection to SMURRF LS $12,000 SCADA Equipment LS $47,000

Subtotal: $3,459,000 Contingency (25%) LS $865,000


4.3 Alternative 3 - SMURRF Supplemental Flows 4.3.1 Project Description The third alternative for the Pier Watershed involves diverting all runoff generated from an 85th percentile, 24-hour storm event within the Pier Watershed to the SMURRF for non-potable uses. As with alternative discussed previously in Section 4.2, this system would expand the existing diversion system that was installed along the Pier Watershed Storm Drain. Runoff would be conveyed to a holding tank, similar in size to the previous alternative (5.02 acre-feet of storage), to settle out particles and remove gross solids, as partial treatment is required to ensure proper functioning of the treatment system. The diversion to the holding tank would use gravity to reduce costs. The runoff would be retained for use by the SMURRF with no additional flows leaving the system. As the SMURRF’s delivery capacity increases to match its design capacity, the detention time at the holding tank would be minimized. The runoff in the holding tank would be conveyed to the SMURRF as the capacity is available. The system would include use of SCADA system to enhance the performance with logic built-in to divert the runoff. A schematic drawing is presented in Appendix D.

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4.3.2 Potential Barriers Potential barriers to the implementation of this alternative are identified in this section so that considerations can be evaluated for their value. One potential barrier would be the location of existing subsurface utilities. The routing of the diversion piping may have to be modified to avoid existing utilities and the cost associated with relocating them. System design should consider vector proofing the system as the runoff will be retained for much longer periods than are recommended by Vector Control Districts. Thinking in the long-term, the seawater and groundwater levels may rise and present potential issues. To combat this issue, it is recommended that the system be designed such that it is not buoyant when empty. 4.3.3 Cost Estimate The cost analysis was developed using various sources of information as well as the cost estimator’s best judgment. The construction cost entails various components of the project to be constructed. Similar project components have been completed in Los Angeles County and the bids for these projects served as one source of reference when evaluating costs. Standard engineering procedures were used to determine a cost estimate as noted in Table 4-3.




Subtotal: $509,000 Construction Mobilization LS $371,000 Excavation 18,500 CY $129,000 Soil Export 7,400 CY $215,000 Trenching and Backfill 2,400 CY $181,000 Diversion Upgrade (Gravity) LS $54,000 Reinforced Concrete Pipe 1,700 LF $296,000 Trash Rack LS $34,000 Holding Tank LS $2,736,000 Connection to SMURRF LS $12,000 SCADA Equipment LS $47,000



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4.4 Alternative 4 - Local Infiltration System with SMURRF 4.4.1 Project Description The fourth alternative for the Pier Watershed involves utilizing a local infiltration system along with the SMURRF to retain the runoff produced by the 85th percentile, 24-hour storm event. A local infiltration system was evaluated as an alternative concept, similar to the Hermosa Strand project, which captured and infiltrated runoff from the Hermosa Beach Pier Storm Drain in a 1,000-foot infiltration trench adjacent to the Strand (City of Hermosa Beach, 2012). The local infiltration system would also utilize the capacity of the SMURRF and the remainder of the runoff would be infiltrated. As with the alternatives discussed in the previous sections, this system would expand the existing diversion system that was installed along the Pier Watershed Storm Drain. Runoff would be conveyed to a holding tank, similar in size to the previous alternative (5.02 acre-feet of storage), in order to settle out particles and remove gross solids, especially for the runoff being conveyed to the SMURRF, as partial treatment is required to ensure proper functioning of the treatment system. The diversion would utilize a gravity system to reduce cost. Runoff exceeding the SMURRF capacity (50,000 gallons or 0.15 acre-feet per day) (Eren, 2014c) for each of the three days would be pumped to an infiltration area similar to the Hermosa Strand project, which would be located adjacent to Ocean Front Walk. The system would include use of SCADA to enhance the performance of the system with logic built-in to divert the runoff amongst the various uses. It is recommended that a minimum of two feet of ground cover is provided over the infiltration system and a three foot minimum separation should be provided between the groundwater table and the invert of the infiltration system. Based on the groundwater table depths identified in the field investigation performed by the City, illustrated in Figure 2-6, the groundwater depth would be approximately 9 feet near the infiltration area, therefore the depth of the infiltration facility would be no greater than four feet, requiring the system to be approximately 16,000 square feet, assuming a three day drawdown time and an infiltration rate of two inches per hour. A schematic drawing is presented in Appendix E. 4.4.2 Potential Barriers Potential barriers to the implementation of this alternative are identified in this section so that considerations are made apparent prior to deciding on the best alternative. One potential barrier would be the location of existing subsurface utilities. The routing of the diversion piping may have to be modified to avoid existing utilities and the cost associated with relocating them. The area required for the infiltration system is very large due to the shallow groundwater. The area required may be a barrier because the space may not be available for both the holding tank and infiltration system and the large footprint would result in a higher cost. The existing groundwater depth and available space may present barriers for project implementation. The system required for infiltration is extremely large and depending on a system that is relatively new for such a large volume may be considered risky. The studies associated with the Hermosa Strand project (Hermosa Beach, 2012) demonstrate that numerous problems arose during construction and throughout the first year of operations. The problems include, but are not limited to, system clogging, seawater intrusion, foul odors, and elevated groundwater table. The study also explains that the runoff pumped into the infiltration system travel laterally to the ocean, and over time mix with the offshore water. The water quality testing "indicate that the frequencies of detection of bacteria for pre- and post-construction scenarios are not statistically different" (Hermosa Beach, 2012). The system designed for the Hermosa Strand is much smaller than the system required for the Pier Watershed, therefore it may be risky to construct such a large system without fully understanding how the system will behave and if

- 22 -


water quality will improve. The barriers the Hermosa Strand project faced would be potential barriers for this project. 4.4.3 Cost Estimate The cost analysis was developed using various sources of information as well as the cost estimator’s best judgment. The construction cost entails various components of the project to be constructed. Similar project components have been completed in Los Angeles County and the bids for these projects served as one source of reference when evaluating costs. Standard engineering procedures were used to determine a cost estimate as noted in Table 4-4.




Subtotal: $564,000 Construction Mobilization LS $410,000 Excavation 23,000 CY $160,000 Soil Export 10,000 CY $232,000 Trenching and Backfill 2,600 CY $196,000 Diversion Upgrade (Gravity) LS $54,000 Reinforced Concrete Pipe 2,000 LF $348,000 Trash Rack LS $34,000 Holding Tank LS $2,736,000 Connection to SMURRF LS $12,000 Proprietary Infiltration Units LS $254,000 Pumping System to Infiltration Units LS $21,000 SCADA Equipment LS $47,000



- 23 -


4.5 Alternative 5 - Diversion plus Local Infiltration System with

SMURRF 4.5.1 Project Description The fifth alternative for the Pier Watershed involves utilizing a local infiltration system along with a diversion to the sanitary sewer and the SMURRF to address the runoff generated by an 85th percentile, 24-hour storm event within the Pier Watershed, a combination of the project alternatives presented in previous sections. The runoff exceeding the capacity of the SMURRF would be addressed through a combination of infiltration and diversion to the sanitary sewer. Similar to the other alternatives, the existing diversion system along the Pier Watershed Storm Drain would be expanded in order to accommodate the additional runoff. Runoff would be conveyed to a holding tank, similar in size to the previous alternatives (5.02 acre-feet of storage), in order to settle out particles and remove gross solids, especially for the runoff being conveyed to the SMURRF, as partial treatment is required to ensure proper functioning of the treatment system. The diversion would utilize a gravity system to minimize costs. A schematic drawing is presented in Appendix F. There are a lot of unknown factors associated with infiltration projects along the beach in the sand, as demonstrated by the Hermosa Strand project previously discussed in Section 4.4. It may be beneficial to implement a smaller infiltration area than what would be required if only infiltration was utilized so that the system behavior and benefits can be monitored throughout its operation to determine if the project concept functions as intended. The system would include use of SCADA to enhance the performance of the system with logic built-in to divert the runoff amongst the various uses. The system would pump runoff to both the infiltration area and the sanitary sewer diversion. Assuming that the SMURRF has the capacity up to 50,000 gallons (0.15 acre-feet) per day (Eren, 2014c) for each of the three days, approximately 4.56 acre-feet of runoff would still require mitigation. If an infiltration gallery with a foot print of 3,500 square feet is utilized (with an assumed drawdown time of three days and infiltration rate of two inches per hour), 0.96 acre-feet of runoff would be mitigated through infiltration and the remaining 3.59 acre-feet would be diverted to the sanitary sewer. 4.5.2 Potential Barriers Potential barriers to the implementation of this alternative are the same as the barriers discussed previously. Additional barriers may arise from this alternative because there are many components, potentially causing the design and construction process to be more difficult, resulting in a higher cost. 4.5.3 Cost Estimate The cost analysis was developed using various sources of information as well as the cost estimator’s best judgment. The construction cost entails various components of the project to be constructed. Similar project components have been completed in Los Angeles County and the bids for these projects served as one source of reference when evaluating costs. Standard engineering procedures were used to determine a cost estimate as noted in Table 4-5.

- 24 -





Subtotal: $534,000 Construction Mobilization LS $389,000 Excavation 20,000 CY $140,000 Soil Export 8,000 CY $232,000 Trenching and Backfill 2,600 CY $196,000 Diversion Upgrade (Gravity) LS $54,000 Reinforced Concrete Pipe 2,000 LF $348,000 Trash Rack LS $34,000 Holding Tank LS $2,736,000 Connection to Sanitary Sewer LS $12,000 Connection to SMURRF LS $12,000 Proprietary Infiltration Units LS $55,000 Pumping System to Infiltration Units LS $16,000 SCADA Equipment LS $47,000



- 25 -


5. Cost Benefit Analysis The alternatives discussed in the previous section cannot be directly compared based on construction cost. The alternatives that utilize SMURRF will have the additional benefit of providing revenue for the recycled water serviced to the community. Additionally, the alternatives that utilize the sanitary sewer will accrue a service fee associated with the use of the sewer lines. Each of the alternatives will also have different annual operations and maintenance (O&M) costs. Table 5-1 identifies the annual costs and benefits associated with SMURRF revenue, sanitary sewer fees, and O&M costs assuming fifteen storm events equivalent to the 85th percentile, 24-hour storm occur each year. The O&M cost is assumed to be two percent of the construction cost. The sewer fee is complex and based on the conveyance, flow rate, and quality. Based on the last two fiscal years, an average rate of $2,000 per million gallons was used for this analysis (Eren, 2014c). The revenue generated by the SMURRF is based on a rate of $2.36 per hundred cubic feet (Eren, 2014b).

Table 5-1 Cost Benefit Analysis Matrix

Alternative Construction Cost

Annual Cost/Benefit 20-Year Life

O&M Sewer Fee SMURRF 1 ($1,999,000) ($25,660) ($49,100) - ($3,492,200) 2A ($6,329,000) ($82,240) ($44,600) $7,100 ($8,723,800) 2B ($5,328,000) ($69,180) ($44,600) $7,100 ($7,461,600) 3 ($6,265,000) ($81,440) - $77,400 ($6,345,800) 4 ($6,926,000) ($90,020) - $7,100 ($8,584,400) 5 ($6,563,000) ($85,300) ($35,200) $7,100 ($8,831,000)

The 20-year life cost of the project can vary if revenue rates change for SMURRF or if the rate for potable water changes. Additionally, if the number of properties receiving recycled water from SMURRF increases, SMURRF can operate at design capacity, reducing reliance on potable water for the City.

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6. Global Changes The Sustainable City Plan for the City of Santa Monica was adopted in 1994 and has been updated and/or revised three times with the most recent update being in January 2014. This plan outlines how the power of the community will be used to enhance resources, prevent harm to the natural environment and human health, and benefit the social and economic well-being of the community for the sake of current and future generations. The Sustainable City Plan identifies goals and strategies for nine areas along with indicators to measure progress towards meeting specified goals. Report cards are completed throughout the process to measure progress and establish new goals. Within the Resource Conservation area identified in the Sustainable City Plan, the targets for 2020 associated with water use are as follows:

Reduce water demand by 1,300,000 gallons per day; Reduce per capita use to 123 gallons per capita per day; Increase to 100 percent local source (self sufficiency); Upward trend in non-potable use.

Within the Environmental and Public Health area identified in the Sustainable City Plan, the targets for 2020 associated with urban runoff reduction are as follows:

Annual reduction in effective impervious area; Annual increase in total acreage treated; and Annual increase in gallons of polluted runoff treated.

The project alternatives discussed in this study positively contribute to the goals outlined in the Sustainable City Plan. Utilizing the SMURRF helps increase non-potable water use and reduces the need for imported water, consistent with the self sufficiency goal of 2020. The project alternatives also increase the total acreage of treated urban runoff and increase the gallons of polluted runoff treated. The project alternatives present multi-benefit solutions that are not only consistent with the Sustainable City Plan, but also contribute to compliance with the MS4 Permit as regional EWMP projects.

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7. References AQUAVEO. 2012. WMS 9.1 Tutorial Watershed Modeling - MODRAT Interface (GIS-Based). AQUAVEO. 2012. WMS 9.1 Tutorial Watershed Modeling - MODRAT Interface (Map-Based). Blake, T.F. 2001. FRISKSP (Version 4.00), A Computer Program for the Probabilistic Estimation of Peak Acceleration and Uniform Hazard Spectra Using 3-D Faults as Earthquake Sources. Blake, Thomas F. 2000. LIQUEFY 2, Interim Version 1.5, A Computer Program for the Estimation of Liquefaction Potential of Soils. California Building Standards Commission. 2007. California Building Code, Title 24, Part 2, Volumes 1 and 2, based on 2006 International Building Code, effective January 1, 2008. California Department of Conservation, Division of Mines and Geology, State of California. 1999. Seismic Hazard Zones Official Map, Beverly Hills Quadrangle, 7.5-Minute Series: Scale 1:24,000, Open-File Report 98-14, dated March 25. California Regional Water Quality Control Board, Los Angeles Region. 2012. Waste Discharge Requirements for Municipal Separate Storm Sewer System (MS4) Discharges Within the Coastal Watersheds of Los Angeles County, Except Those Discharges Originating from the City of Long Beach, NPDES Permit No. CAS004001, Order No. R4-2012-0175. City of Hermosa Beach. Prepared by Geosyntec. August 2012. Project Certification Report; Phase I Hermosa Strand Infiltration Trench. City of Santa Monica. April 1999. City of Santa Monica Environmental and Public Works Management Department. Volume 2 - Drawings for the Construction of Moss Avenue Pump Station Phase 2. Prepared by Montgomery Watson. City of Santa Monica. September 1999, updated January 2014. Sustainable City Plan. City of Santa Monica. June 2009. City of Santa Monica Public Works Department. Pier Storm Drain Improvement Project and Dry Weather Diversion Structure. Prepared by RBF Consulting. City of Santa Monica. June 25, 2014 (2014a). Pier Watershed Geodatabase File (PierWatershed.gdb). Email from Selim Eren to Vik Bapna. City of Santa Monica. October 10, 2014 (2014b). Pier Watershed Feasibility Draft Meeting. Participants: Selim Eren, Rick Valte, Vik Bapna, and Gary Welling. Dibblee, T.W., Jr. 1991. Geologic Map of the Beverly Hills and Van Nuys (South 1/2) Quadrangles, Los Angeles County, California: Dibblee Foundation, DF-31, Scale 1:24,000. Eren, Selim. July 29, 2014 (2014a). Pier Watershed Meeting. City of Santa Monica, California. Eren, Selim. August 12, 2014 (2014b). Re: SM - Pier Watershed. Email to Vik Bapna. Eren, Selim. August 28, 2014 (2014c). SMURRF Capacity and Use. Email to Katie Harrel.

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Hart, E.W., and Bryant, W.A. 1997. Fault-Rupture Hazard Zones in California, Alquist-Priolo Earthquake Fault Zoning Act with Index to Earthquake Fault Zone Maps: California Department of Conservation, Division of Mines and Geology, Special Publication 42, with Supplements 1 and 2 added in 1999. Los Angeles County Department of Public Works (LACDPW), Water Resources Division. 2004. 85th Percentile 24-Hour Rainfall Depth Analysis within the County of Los Angeles. Los Angeles County Department of Public Works (LACDPW). January 2006. Hydrology Manual. National Environmental Title Research, LLC. http://historicaerials.com/. Accessed July 15, 2014. Ninyo & Moore. December 26, 2008. Geotechnical Evaluation Pier Storm Drain Improvement Project (SP2101) Santa Monica, California. Prepared for RBF Consulting. Norris, R.M., and Webb, R.W. 1990. Geology of California, Second Edition: John Wiley & Sons. Seed, H.B., and Idriss, I.M. 1982. Ground Motions and Soil Liquefaction During Earthquakes, Earthquake Engineering Research Institute Monograph, Oakland, California. Tokimatsu, K., and Seed, H.B. 1987. Evaluation of Settlements in Sands Due to Earthquake Shaking, Journal of the Geotechnical Engineering Division, ASCE, Vol. 113, No. 8, pp. 861-878. United States Environmental Protection Agency. 2012. Managing Urban Runoff. http://water.epa.gov/polwaste/nps/outreach/point7.cfm. United States Geological Survey. 2008. Earthquake Ground Motion Parameter Java Application, Java Ground Motion Parameter Calculator – Version 5.0.8; http://earthquake.usgs.gov/research/hazmaps/design/. Youd, T.L., Hansen, C.M., and Bartlett, S.F. 2002. Revised Multilinear Regression Equations for Prediction of Lateral Spread Displacement, Journal of Geotechnical and Geoenvironmental Engineering, ASCE., Vol. 128, No. 12, pp. 1007-1017.

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http://historicaerials.com/

http://water.epa.gov/polwaste/nps/outreach/point7.cfm

http://earthquake.usgs.gov/research/hazmaps/design/

Appendix B

Alternative 1 - Sanitary Sewer Diversion Schematic Drawing

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October 2014±

Appendix C

Alternative 2 - Sanitary Sewer Diversion with SMURRF Schematic Drawing

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October 2014±

Appendix D

Alternative 3 - SMURRF Supplemental Flows Schematic Drawing

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October 2014±

Appendix E

Alternative 4 - Local Infiltration System with SMURRF Schematic Drawing

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EXISTING CLARIFIERHOLDING TANK

60" SDRC P

MOSS A VEN UE

S E AS IDE TERRACEPALISADES BEACH ROAD

PACIFIC COAST HWY

OCEAN FRONT WALK

COLORADOAVENUE

APPIAN WAY

CONNECT TO SMURRF

INFILTRATION SYSTEM


0 50 10025Feet

!( Sanitary Sewer Manhole!( Proposed Pump System^ SMURRF

Proposed ConveyanceExisting Sanitary SewerExisting Storm Drain Force MainExisting Storm DrainProposed Infiltration SystemProposed Holding Tank

Alternative 4 - Local Infiltration System with SMURRF


October 2014±

Appendix F

Alternative 5 - Diversion plus Local Infiltration with SMURRF Schematic Drawing

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EXISTING CLARIFIERHOLDING TANK

60" SS RCP

60" SDRCP

MOSS AV ENU E

SE ASIDE TERRACEPALISADES BEACH ROAD

PACIFIC COAST HWY

OCEAN FRONT WALK

COLORADOAVENUE

APPIAN WAY

CONNECT TO SMURRF

INFILTRATION SYSTEM


24" VCP

CONNECT TO EXISTINGSANITARY SEWER

(ALTERNATIVE)


0 50 10025Feet


Proposed ConveyanceProposed Conveyance AlternativeExisting Sanitary SewerExisting Storm Drain Force MainExisting Storm DrainProposed Holding TankProposed Infiltration System

Alternative 5 - Diversion plus Local Infiltration System with SMURRF


October 2014±

Pier Watershed Alternatives Feasibility Study

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Transcript of Pier Watershed Alternatives Feasibility Study