Malletts Bay Stormwater Management System & Transportation … · 7.3.4 Stormwater Management...

SCOPING STUDY

Malletts Bay Stormwater Management System & Transportation Scoping Study Colchester, Vermont

PREPARED FOR

PREPARED BY

NOVEMBER 2017

The preparation of this report has been financed in part through grant from the Federal Highway Administration and Federal Transit Administration, U.S. Department of Transportation, under the State

Planning and Research Program, Section 505 [or Metropolitan Planning Program, Section 104(f)] of Title 23, U.S. Code, as well as matching funds provided by Chittenden County’s municipalities and the Vermont

Agency of Transportation. The contents of this report do not necessarily reflect the official views or policy of the U.S. Department of Transportation

Malletts Bay Stormwater Management System & Transportation Scoping Study

i Table of Contents

Table of Contents

Introduction .................................................................................................................................................... 5

Project Overview ............................................................................................................................................................... 6 Purpose and Need Statements ................................................................................................................................... 9

1.2.1 West Lakeshore Drive Bicycle and Pedestrian Enhancements ...................................................... 9 1.2.2 Lakeshore Drive / Blakely Road Intersection Enhancements ......................................................... 9 1.2.3 Malletts Bay Stormwater Management System ............................................................................... 10

Coordination with Other Projects ........................................................................................................................... 11

Existing Transportation Conditions ........................................................................................................... 12

Project Site Description .............................................................................................................................................. 13 Land Use Characteristics ............................................................................................................................................ 13 West Lakeshore Drive Roadway Characteristics ............................................................................................... 13 Bayside Intersection Characteristics ...................................................................................................................... 14 Crash Assessment ......................................................................................................................................................... 15 Review of Previous Studies ....................................................................................................................................... 15

2.6.1 1998 Route 127 Corridor Study ............................................................................................................. 15 2.6.2 2001 Route 127 Scoping Study .............................................................................................................. 16 2.6.3 2008 West Lakeshore Drive Conceptual Development Plan ...................................................... 16 2.6.4 2015 Bayside Build-Out Study ................................................................................................................ 16 2.6.5 2015 AARP Street and Sidewalk Audit ................................................................................................ 17

Existing Stormwater Conditions ................................................................................................................. 19

Project Area Description ............................................................................................................................................ 20 Review of Previous Studies ....................................................................................................................................... 22

3.2.1 2008 Smith Creek Stream Geomorphic Assessment ..................................................................... 22 3.2.2 2013 Town-Wide Integrated Water Resources Management Plan ......................................... 22 3.2.3 2015 Northern Lake Champlain Direct Drainages (Basin 5) Tactical Basin Plan ................. 23 3.2.4 2016 Malletts Bay Initiative ...................................................................................................................... 24 3.2.5 2017 All-Hazards Mitigation Plan .......................................................................................................... 24

Existing Roadway Drainage System ....................................................................................................................... 24 3.3.1 Sub-Basin Delineations .............................................................................................................................. 24 3.3.2 Stormwater Infrastructure Inventory .................................................................................................... 26 3.3.3 Lakeshore Drive Drainage Observations and Outfall Inspections ............................................ 28 3.3.4 Hydrologic / Hydraulic Assessment of Selected Sub-Basins and Drainage Systems ....... 31

Existing Roadway Drainage and Stormwater Systems Summary .............................................................. 36

Resources Assessment ................................................................................................................................. 40


ii Table of Contents

Cultural Resources ........................................................................................................................................................ 41 Natural Resources ......................................................................................................................................................... 41

Meetings & Public Outreach ....................................................................................................................... 47

Public Meetings ............................................................................................................................................................. 48 Opportunities ................................................................................................................................................................. 48 Concerns .......................................................................................................................................................................... 48

Online Survey .................................................................................................................................................................. 49

Planning and Design Criteria ...................................................................................................................... 50

Transportation Alternatives Design Criteria ....................................................................................................... 51 Stormwater Alternatives Design Criteria .............................................................................................................. 54

Alternatives Analysis .................................................................................................................................... 56

Lakeshore Drive and Blakely Road Intersection Alternatives ....................................................................... 57 7.1.1 Intersection Alternative I – No Build .................................................................................................... 57 7.1.2 Intersection Alternative II (A) – Operational Modifications ......................................................... 58 7.1.3 Intersection Alternative II (B) – Operational & Geometric Modifications .............................. 60 7.1.4 Intersection Alternative III – Roundabout .......................................................................................... 62 7.1.5 Intersection Alternative IV (A) – East Lakeshore Drive Reconfiguration ................................ 64 7.1.6 Alternative IV (B) – East Lakeshore Drive Dead End ....................................................................... 66 7.1.7 Bayside Intersection Evaluation Matrix ............................................................................................... 68

Bicycle and Pedestrian Improvement Alternatives .......................................................................................... 70 7.2.1 West Lakeshore Drive Alternative I – No Build ................................................................................ 70 7.2.2 West Lakeshore Drive Alternative II – Shared Travel Lanes ........................................................ 70 7.2.3 West Lakeshore Drive Alternative III – On Road Bike Lanes ....................................................... 71 7.2.4 West Lakeshore Drive Alternative IV – Southern Shared Use Path .......................................... 71 7.2.5 West Lakeshore Drive Alternative IV (A) – Shared Use Path with Waterfront Access ...... 73 7.2.6 West Lakeshore Drive Alternative IV (B) – Shared Use Path with Scenic Overlook ........... 73 7.2.7 West Lakeshore Drive Alternative IV (C) – Northern Sidewalk Extension .............................. 73 7.2.8 West Lakeshore Drive Alternatives Evaluation Matrix ................................................................... 74

Stormwater Management Alternatives ................................................................................................................ 76 7.3.1 Stormwater Management System Alternative: Meeting Standards ........................................ 76 7.3.2 Stormwater Management System Alternative: Exceeding Standards ..................................... 77 7.3.3 Stormwater Management System Alternatives Summary ........................................................... 77 7.3.4 Stormwater Management System Recommendation Details, Metrics, and Costs ............. 81 7.3.5 Alternatives Evaluation Criteria and Scoring ..................................................................................... 86

Selection of Preferred Alternatives ............................................................................................................ 89

Bayside Intersection Preferred Alternative .......................................................................................................... 90 West Lakeshore Drive Preferred Alternative ...................................................................................................... 92 Stormwater Preferred Alternative ........................................................................................................................... 94


iii Table of Contents

List of Tables

Table No. Description Page

Table 1: High Crash Location Summary ...................................................................................................... 15

Table 2: Summary of Existing Roadway Drainage System Conveyance Capacity (East and West Lakeshore

Drive) ........................................................................................................................................................... 32

Table 3: Sub‐Basin Assessment Summary .................................................................................................. 39

Table 4: West Lakeshore Drive Bicycle & Pedestrian Improvements Design Criteria ................................ 52

Table 5: Intersection Improvement Design Criteria .................................................................................... 53

Table 6: Stormwater Management System Design Criteria ....................................................................... 55

Table 7: Intersection Capacity Analysis Summary – Alternative I ............................................................... 58

Table 8: Intersection Capacity Analysis Summary – Alternative II (A) ........................................................ 60

Table 9: Intersection Capacity Analysis Summary – Alternative II (B) ........................................................ 61

Table 10: Intersection Capacity Analysis Summary – Alternative III ........................................................... 63

Table 11: Intersection Capacity Analysis Summary – Alternative IV (A) ..................................................... 66

Table 12: Intersection Capacity Analysis Summary – Alternative IV (B) ..................................................... 67

Table 13: BMP Type and P Removal Efficiency ........................................................................................... 82

Table 14: BMP Type and Unit Construction Cost ........................................................................................ 84

Table 15: Sub‐Basin Recommendation Summary ....................................................................................... 85


iv Table of Contents

List of Figures

Figure No. Description Page

Figure 1: Project Area Map ........................................................................................................................... 7

Figure 2: West Lakeshore Drive Corridor Map ............................................................................................. 8

Figure 3: 2015 Bayside Build‐Out Alternatives Overall Intersection Capacity Summary ........................... 17

Figure 4: Stormwater Management System Project Area .......................................................................... 21

Figure 5: Sub‐Basin Delineations for Transportation Related Drainage Systems ....................................... 25

Figure 6: Stormwater Infrastructure Inventory .......................................................................................... 27

Figure 7: Lakeshore Drive Existing Drainage Observations and Outfall Assessment .................................. 30

Figure 8: Williams Road Cross Culvert Subwatershed Mapping ................................................................. 34

.................................................................................................................................................................... 35

Figure 9: Country Meadows Subwatershed Mapping ................................................................................ 35

Figure 10: Summary of Existing Water Quality Treatment Status for Town Roadway Drainage Areas ..... 38

Figure 11: Identified and Excavated National Historic Sites ....................................................................... 43

Figure 12: Natural Resources Map .............................................................................................................. 44

Figure 13: Intersection Alternative II (A) ..................................................................................................... 59

Figure 14: Intersection Alternative II (B) ..................................................................................................... 61

Figure 15: Intersection Alternative III ......................................................................................................... 63

Figure 16: Intersection Alternative IV (A) ................................................................................................... 65

Figure 17: Intersection Alternative IV (B) ................................................................................................... 67

Figure 18: Bayside Intersection Alternatives Evaluation Matrix ................................................................. 69

Figure 19: Shared Travel Lanes Cross Section ............................................................................................. 70

Figure 20: On Road Bike Lanes Cross Section ............................................................................................. 71

Figure 21: Shared Use Path Cross Section .................................................................................................. 72

Figure 22: Alternative IV (C) – Northern Sidewalk Extension ..................................................................... 74

Figure 23: West Lakeshore Drive Alternatives Evaluation Matrix .............................................................. 75

Figure 24: Summary of “Greened” Acres Possible for Town Roadway Drainage Areas ............................. 79

Figure 25: Summary of Maximum Percent Reduction in Annual Total Phosphorus Load by Watershed and

Alternative .................................................................................................................................................. 80

Figure 26: Summary of Implementation Costs per Pound of Annual Total Phosphorus Load Reduction by

Watershed and Alternative ......................................................................................................................... 81

Figure 27: Bayside Intersection Preferred Alternative ............................................................................... 91

Figure 28: West Lakeshore Drive Preferred Alternative ............................................................................. 93

Figure 29: Stormwater Preferred Alternatives Implementation Costs ....................................................... 94


5 Introduction

1 Introduction Malletts Bay is the recreational center of the Town of Colchester containing local parks, waterfront access, campgrounds, and the Lake Champlain bikeway. This report combines three separate Scoping Studies which examine opportunities to: 1) enhance stormwater management throughout the project study area, 2) improve bicycle and pedestrian safety and mobility along West Lakeshore Drive, and 3) improve intersection operations and safety for all modes at the West Lakeshore Drive/Blakey Road intersection. Each of the scoping processes examined existing and future conditions, incorporated public and stakeholder input, and resulted in a set of preferred alternatives which were approved by the Colchester Selectboard in October 2017.


6 Introduction

Project Overview This scoping study identifies and evaluates alternatives that address stormwater management, bicycle and pedestrian accommodations along West Lakeshore Drive, and improvements at the Blakely Road and Lakeshore Drive intersection.

The Stormwater Management System evaluation builds upon Colchester’s Clean Water and Malletts Bay Initiatives and takes into account future State requirements to reduce runoff and pollutants in waters that discharge into Inner Malletts Bay. The project area consists of the East and West Lakeshore Drive area and the upland watersheds of Crooked Creek, Smith Creek, and Moorings Stream (Shore Acres). The alternatives evaluated include various Green Stormwater Infrastructure (GSI) and other Low Impact Development (LID) treatment practices. The stormwater work also involves sub-basin delineation and watershed descriptions for each watershed within the project area.

The West Lakeshore Drive corridor from Prim Road to Blakely Road was evaluated to identify effective strategies to enhance bicycle and pedestrian safety and mobility. Through the scoping process, several alternatives were identified and evaluated to arrive at a preferred alternative.

The intersection of Blakely Road and Lakeshore Drive was evaluated to identify recommendations to improve overall intersection operations and better accommodate vehicle, bicycle and pedestrian traffic now and in the future.

The project study area is shown in Figure 1 and the West Lakeshore Drive corridor is shown in Figure 2.


7 Introduction

Figure 1: Project Area Map


8 Introduction

Figure 2: West Lakeshore Drive Corridor Map


9 Introduction

Purpose and Need Statements

1.2.1 West Lakeshore Drive Bicycle and Pedestrian Enhancements

Purpose

The Purpose of the West Lakeshore Drive Bicycle and Pedestrian Enhancements project is to improve the safety and mobility of pedestrians and cyclists along the West Lakeshore Drive corridor between Blakely Road and Prim Road.

Need

Project needs, as defined by the Town of Colchester, project team members, and the public at the Local Concerns Meeting are:

Lack of safe bicycle facilities: Currently, most cyclists traveling along West Lakeshore Drive use the roadway shoulder, which varies in width from one to three feet. This narrow shoulder is marginally adequate for experienced cyclists and is generally not utilized by other cyclists.

Pedestrians and cyclist conflicts on West Lakeshore Drive sidewalk: Due to the lack of a safe bicycle facility along West Lakeshore Drive, some cyclists use the existing sidewalk along the south side of Lakeshore Drive leading to potential conflicts with pedestrians along the sidewalk.

Missing path connection between Prim Road and Bayside Park: There is currently no recreational path between the Town’s existing path system at Bayside Park and the planned multi-use path along West Lakeshore Drive west of Prim Road.

1.2.2 Lakeshore Drive / Blakely Road Intersection Enhancements

Purpose

The Purpose of the Lakeshore Drive / Blakely Road Intersection Enhancements project is to identify and develop a preferred approach to improve safety and operational efficiency for all users through the Lakeshore Drive / Blakely Road intersection and adjacent area.

Need

Project needs, as defined by the Town of Colchester, project team members, and the public at the Local Concerns Meeting are:

Insufficient intersection capacity: The current signalized intersection configuration experiences moderate to significant delay and queuing during weekday peak periods and the summer seasonal peak. This is demonstrated by the Level of Service D and volume-to-capacity ratio of 0.82 occurring during the current weekday evening peak hour and the projected Level of Service E and volume-to-capacity ratio of 0.99 projected during the 2037


10 Introduction

weekday evening peak hour. The intersection accommodates relatively heavy commuter traffic flows traveling from East Lakeshore Drive to West Lakeshore Drive and significant pedestrian crossing volumes during the summer months.

Existing safety issues: The intersection is designated as a High Crash Location in the current (2010-2014) VTrans High Crash Location report. Between 2011 and 2015 there were 33 reported crashes at the intersection, with two reported crashes involving injuries.

Inadequate pedestrian accommodations: The intersection lacks several pedestrian safety and accessibility related items to accommodate both routine and peak seasonal pedestrian crossing demands. These items include the lack of detectable warning surfaces at the sidewalk ramps, lack of crosswalk striping across the recreational fields parking lot access, and lack of pedestrian countdown timers. Additionally, the July 2015 AARP Vermont Street and Sidewalk Audit noted that the current signal provides inadequate pedestrian crossing time.

1.2.3 Malletts Bay Stormwater Management System

Purpose

The purpose of the Malletts Bay Stormwater Management System project is to reduce public roadway and private property damage due to inadequate management of stormwater from town-owned roadways within watersheds draining to the easterly and southern shores of Inner Malletts Bay, and to reduce the volume of stormwater, sediment and phosphorus currently being discharged from roadways to Malletts Bay. The comprehensive suite of stormwater management strategies for Town-owned roadways will support Colchester’s Clean Water and Malletts Bay Initiatives and will leverage future transportation and utility-related infrastructure projects to protect and enhance water quality.

Need

Project needs, as defined by the Town of Colchester, project team members, and the public at the Local Concerns Meeting include:

Insufficient roadway drainage infrastructure:

o Roadways and sidewalks have standing water following rain events or periods of snowmelt.

o Significant roadway deterioration has occurred as a result of poor drainage.

o Private properties in portions of the project area are negatively impacted by uncontrolled run-on from roadways during rain events.

Excessive loadings of stormwater volume, sediment, and nutrients:


11 Introduction

o During rainfall events, insufficient, aging, or missing stormwater management measures in the project area result in delivery of untreated or insufficiently treated runoff from roadways to tributary streams and to Inner Malletts Bay.

o Where runoff is channeled from roadways via ditches or closed drainage systems to streams without treatment, erosion and gullying results in transport of sediment into streams, and creates channel and streambank instability with additional transport of sediment and nutrients to Malletts Bay.

Coordination with Other Projects The Town of Colchester is undertaking numerous improvements to the Malletts Bay area and upland watersheds through various programs, mostly falling under the titles of the Malletts Bay Initiative and the Clean Water Initiative. The Malletts Bay Initiative includes nine different projects, three of which are included in this scoping study (shown in bold).

Malletts Bay Stormwater System

Blakely Road/East Lakeshore Drive/ West Lakeshore Drive Intersection Improvements

West Lakeshore Drive Pedestrian Improvements

Malletts Bay Sewer System

Re-Zoning to Include Low Impact Development Standards

Colchester Recreation and Community Center

Blakely Road/Laker Lane Intersection Improvements

West Lakeshore Drive/Prim Road Intersection Improvements


12 Existing Transportation Conditions

2 Existing Transportation Conditions To produce recommendations which best suit the needs of the Town of Colchester, existing conditions in the study area must be understood. The existing traffic conditions, land uses, and cultural and environmental resources were compiled and evaluated as the first stage of this scoping study. Many past studies have been conducted regarding the West Lakeshore Drive corridor, so a review of these past studies and reports was also conducted to get the full picture of the existing land uses and accompanying transportation network. A description and analysis of these existing conditions are provided in this chapter.



Project Site Description The project site is located in Colchester, Vermont directly adjacent to Malletts Bay. along West Lakeshore Drive (VT 127) between Prim Road and Blakely Road as well as at the eastern terminus intersection of East and West Lakeshore Drives at Blakely Road. The project intersection is located between Bayside Park to the south and Bayside Beach to the north. This corridor is a heavily used commuter route between the Malletts Bay area and points south in Burlington and points north and east in Colchester and Milton. West Lakeshore Drive also serves a large amount of local traffic, particularly in the summer when parks, beaches, and campgrounds are in their peak season. During the summer season, this area is a lively part of town and is prime for walking, bicycling along the Lake Champlain Bikeway, boating, and generally recreating at the park and beach.

Land Use Characteristics Per the Colchester’s Zoning Regulations, land along the West Lakeshore Drive corridor falls into two different zoning districts: Lakeshore 1 includes land between the bay and the road way and Lakeshore 2 includes all non-lakeshore property along West Lakeshore Drive. Land uses are quite diverse along the corridor between Prim Road and Shore Acres Drive. In this area, there are various retail shops such as Mazza’s Store and the Ace Hardware Store as well as small restaurants and a gas station. To the east of Shore Acres Drive, the uses are more recreational and include the International Sailing School, multiple marinas and boat launches, Malletts Bay Campground, and Bayside Park and Beach. The Hazelett-Strip Casting Corporation is located directly to the west of Malletts Bay Campground.

West Lakeshore Drive Roadway Characteristics The following is a brief description of the functional characteristics of West Lakeshore Drive between Prim Road and Blakely Road.

Functional Classification: Minor Arterial

Right of Way (ROW): 3 rods (49.5 feet)

Roadway Geometry: Two 11’ travel lanes in each direction with 1’-4’ paved shoulders and left turn lanes:

Westbound into Malletts Bay Campground Eastbound onto East Lakeshore Drive

Speed Limit: 25 mph

2016 Average Annual Daily Traffic (AADT):

14,000



Surrounding Characteristics:

Utility poles along northern side between Prim Road and Malletts Bay Marina and southern side between Malletts Bay Marina and Blakely Road

Multiple driveways for businesses and residences

No on-street parking Boat launch access

Pedestrian Facilities: Five-foot sidewalk with 0-5’ grass buffer and usually no curb along the southern side of the roadway, terminating at Blakely Road

Five mid-block crosswalks

Bicycle Facilities: None present but part of the Lake Champlain Bikeway

Bayside Intersection Characteristics The intersection of East and West Lakeshore Drives at Blakely Road is situated with Bayside Beach and access to Malletts Bay to the north and Bayside Park to the south. The following is a brief description of the intersection.

Approaches: West Lakeshore Drive (Eastbound) One left turn lane, one through/right turn

lane 25 mph speed limit

East Lakeshore Drive (Southbound) One right turn lane, one through/left turn


Blakely Road (Westbound) One left turn lane, one through/right turn


Bayside Park Entrance (Northbound) One lane

Intersection Type: Signalized

Signal Type: Span wire signals

Pedestrian Facilities: Crosswalks on all approaches with exclusive signal phase



Crash Assessment A crash assessment was performed along the West Lakeshore Drive corridor and at the Bayside intersection. VTrans analyzes crash data yearly and identifies High Crash Locations (HCLs) using two criteria: (1) a minimum of five reported crashes in five years; and (2) the actual-to-critical ratio must be greater than 1.0. According to the 2010-2014 VTrans HCL Report, there are two relevant HCL locations within the study area1. A summary of crashes at these HCL locations is shown in Table 1.

Table 1: High Crash Location Summary

Route/Location Milemarker AADT Crashes Fatalities Injuries Property Damage

Only

Ratio (Actual / Critical)

Ranking

VT 127 / West Lakeshore Drive

2.170 - 2.230 9,850 22 0 13 15 1.36 44

VT 127 / East Lakeshore Drive

3.170 - 3.250 13,080 24 0 3 21 1.075 105

Using the VTrans Public Crash Query Tool, a more in-depth review of crashes from the most recent 5 years of data (2011-2015) at the intersection of East and West Lakeshore Drives at Blakely Road was conducted. In this time period, there were 33 reported crashes, 25 (76%) of which were rear end crashes. It was also found that 70% of reported crashes occurred during daylight hours. A full list of these crashes is provided in the Appendix.

Review of Previous Studies

2.6.1 1998 Route 127 Corridor Study

A review of DuBois & King, Inc.’s Route 127 Corridor Study was conducted to evaluate the current relevance of the study’s proposed shared use path2. The study proposed to install five-foot sidewalks along the north side of West Lakeshore Drive from Prim Road to the slope and guardrail west of Moorings Marina. The sidewalk would then become an eight to ten-foot wide asphalt path that goes halfway down the bank and leads to a 15 to 20-foot wide level landing and overlook. The rest of the bike path would drop to the level of the Marina and return to a new five-foot buffered sidewalk. Another recommendation was to create more visible mid-block crossings. The feasibility of a roundabout at the intersection of East and West Lakeshore Drive at Blakely Road was also evaluated in this report.

1 High Crash Locations Report: Intersections and Sections (2010-2014), Vermont Agency of Transportation, 2015. 2 Route 127 Corridor Study – Final Report, DuBois & King, Inc., Colchester, VT, October 1998.

Bike Safety?

Between 2011 and 2015, there were two reported crashes involving bicyclists along West Lakeshore Drive.



2.6.2 2001 Route 127 Scoping Study

The final report of the 2001 Route 127 Scoping Study, prepared by Dufresne-Henry focused on specific sections of the corridor and analyzed the sustainability of various alternatives3. The preferred alternative (accepted unanimously by the Selectboard) includes a 28-foot wide curbed roadway with a separated 10-foot shared use path on the north side of the roadway and a five-foot sidewalk on the south side of the roadway, both separated from the roadway by a five-foot green belt. The recommendation made at the Bayside intersection was to reassign lane movements as well as to add a median and enhanced crossing at the Blakely Road approach.

2.6.3 2008 West Lakeshore Drive Conceptual Development Plan

A review of the 2008 Conceptual Development Plan for a village center in Mallets Bay and along West Lakeshore Drive was conducted4. The plan includes the realignment of West Lakeshore Drive near Shore Acres Road, relocation of East Lakeshore Drive to intersect Blakely Road at Laker Lane, the expansion of Bayside Park and addition of a waterfront shared use path, and the creation of the Heineberg-Blakely Bypass road. The typical roadway cross-section included the addition of curbing and planting strips along West Lakeshore Drive. Stormwater management issues were also addressed in this plan and it was suggested that the use of pervious buffers should be used while limiting the use of paving as much as possible. Treatment techniques such as rain gardens and infiltration trenches could be incorporated into parking areas and the streetscape.

2.6.4 2015 Bayside Build-Out Study

In 2015, the CCRPC performed a traffic study and land use analysis as part of the Bayside Build-Out Analysis conducted for the Town of Colchester5. The focus of the traffic study was congestion reduction at the intersection of West Lakeshore Drive, East Lakeshore Drive, and Blakely Road and examining future build-out potential.

Given the existing intersection volumes, the Bayside intersection performed at an overall Level of Service (LOS) C with a volume to capacity (v/c) ratio of 0.82 during the PM peak period. There were two movements which performed at nearly full capacity: through and right turning movements from Blakely Road and left turning movements from West Lakeshore Drive.

The No Build and seven build alternatives were studied using a sensitivity analysis which increased base traffic volumes incrementally until a 20 percent increase was achieved and another assessment at a 30 percent increase was also completed.

3 Final Scoping Repot: Route 127, Dufresne-Henry, Colchester, VT, October 2001. 4 West Lakeshore Drive Conceptual Development Plan, PlaceSense, Colchester, VT, April 2008. 5 Jason Charest, Melanie Needle, Sai Sarapelli. CCRPC Staff. Bayside Build-Out Analysis [Memorandum], Chittenden County Regional

Planning Commission, Winooski, VT, August 2015.



Figure 3 comes directly from the study and shows the results of this congestion analysis.

Figure 3: 2015 Bayside Build-Out Alternatives Overall Intersection Capacity Summary

The study’s recommendations were to first update and optimize the existing signal and add an advanced walk phase. The Town selected alternative 3B with a connector roadway between Blakely Road and East Lakeshore Road as their preferred alternative. These alternatives were then used to produce the land use build-out portion of the study.

2.6.5 2015 AARP Street and Sidewalk Audit

In July 2015, AARP Vermont volunteers, local community members, and staff from the CCRPC conducted a street and sidewalk audit along West Lakeshore Drive6. The purpose of this audit was to evaluate the accessibility of the corridor as it relates to pedestrian mobility for those with and without disabilities. The major conclusions drawn from the audit are as follows:

Adopt traffic calming measures to reduce speeds through the corridor such as:

o A designated speed zone through the park, o Additional crosswalks at the Prim Road intersection and along

the corridor, o Increased signage, o Sharrows on the roadway, and o Rectangular rapid flashing beacons at key crosswalks

6 Colchester Street and Sidewalk Audit: Survey Results, AARP Vermont, July 2015.



Increase crossing time at the intersection of East and West Lakeshore Drive by seven seconds,

Provide benches and rest areas along West Lakeshore Drive,

Improve pedestrian accessibility at various access points along the corridor using signage and striping for pedestrian right-of-way,

Use form based code as a tool to promote infill development and repurposing of existing structures and give developers a more flexible. framework while meeting the aesthetic and actual needs of the community.


19 Existing Stormwater Conditions

3 Existing Stormwater Conditions At the onset of this project, the existing stormwater conditions were compiled and analyzed. This data includes the physical characteristics of the existing infrastructure on Town-owned parcels with a focus on roadways along the easterly and southern shores of Malletts Bay and in upland watershed areas. Observational analyses were conducted while the ground was dry as well as during precipitation events. The existing water quality was examined to measure the reductions required to comply with Vermont standards. A complete description and analysis of these existing conditions are provided in this chapter.



Project Area Description The extent of the project area for the Stormwater Management portion of this scoping project represents the entire watersheds of Crooked Creek, Smith Hollow Creek, the Moorings Stream, and other direct drainages to Malletts Bay along West and East Lakeshore Drives (Figure 4). These watershed boundaries were initially developed during the Town of Colchester’s Integrated Water Resource Management (IWRM) planning project (Section 3.3.2). The project area boundary was adjusted only on the north-western edge to exclude Marble Island and Coates Island.

The portion of the project area that drains directly to Malletts Bay includes West Lakeshore Drive between Prim Road and Blakely Road, as well as East Lakeshore Drive from Blakely Road to Bay Road. A mix of commercial and residential uses are clustered near the Blakely Road and Lakeshore Drive intersection, while development along East Lakeshore Drive consists primarily of seasonal and year-round residential development, often with structures located close to the roadway.

The Shore Acres Drive or Moorings Stream watershed area (approximately 350 acres) contains primarily low-density residential development dated to the late 1960s and 1970s. Much of this watershed is underlain by poorly drained soils with limited opportunity for infiltration. In the southern, upper portion of the watershed, stormwater runoff from roadways and developed land is conveyed by grass channels and culverts to overland flow, and then to the Moorings Stream itself. In the portion of the watershed closer to West Lakeshore Drive, two small closed drainage systems convey runoff directly to the stream near the intersection of Shore Acres Drive and Hillcrest Lane. The Moorings Stream itself is conveyed beneath East Lakeshore Drive via a large culvert at the Moorings Marina, where it passes through a series of sediment settling chambers before reaching Malletts Bay.

The Smith Creek watershed area (approximately 1,180 acres) contains a mix of municipal/institutional, residential, and limited agricultural uses. The Town Offices, Colchester Police Department, Colchester Rescue, and the Town Garage, as well as Colchester High School, Colchester Middle School, and the Malletts Bay School, are all located on Blakely Road between Williams Road and Laker Lane. Much of the residential development in this watershed is concentrated on sandy soils in the area between Blakely Road, Interstate 89, and Malletts Bay. The developed land and roadways in this area are served by a variety of open and closed drainage systems, many of which were constructed in the 1970s and 1980s. The watershed area east of I-89 includes one major subdivision on Edgewood Drive, as well as the Town’s Growth Center at Severance Corners.

The Crooked Hollow Creek watershed area (approximately 1,400 acres) is primarily forested or in used for agriculture, with low-density and residential development located along Poor Farm Road and off US Route 7. Two residential subdivisions are located near the northern edge of this watershed. Both developments are served by curb-and-gutter closed drainage systems with permitted surface water discharges to the creek, though the levels of water quality treatment and runoff retention provided by these systems vary widely (Section 3.3).



Figure 4: Stormwater Management System Project Area



Review of Previous Studies In addition to the studies identified in Section 2.6, the following reports were reviewed in the context of stormwater management.

3.2.1 2008 Smith Creek Stream Geomorphic Assessment

Existing Phase 1 and Phase 2 stream geomorphic assessments (SGA) have been performed for a number of Colchester’s streams according to the Stream Geomorphic Assessment Protocols established by the Vermont Department of Environmental Conservation. The Phase 1 SGA protocol involves a general assessment of the stream corridor, primarily through topographic maps and windshield surveys. The Phase 2 SGA protocol involves measurement of numerous stream channel characteristics over designated stream reaches. Within the project area, Phase 1 and Phase 2 geomorphic assessments have been performed only for Smith Creek7, and those data were obtained from VT DEC staff. Several stream impacts were documented during the Phase 2 SGA that are potentially related to stormwater infrastructure, including locations of stormwater inputs, gullying, and erosion, particularly in the lower reaches of the creek between Williams Road and Malletts Bay.

3.2.2 2013 Town-Wide Integrated Water Resources Management Plan

In 2009-2013, the Town completed a town-wide study8 of all wastewater and stormwater infrastructure, funded through a USEPA demonstration grant. The work had three parts: (1) technical - mapping of existing public and private stormwater and wastewater infrastructure town-wide as well as a detailed assessment of septic capacity to support both current development and future build-out; (2) public education - presentation of the technical findings and a participatory process to identify preferred alternatives and approaches; and (3) development of an integrated plan to manage both wastewater and stormwater infrastructure to allow growth and preserve, protect, and manage Colchester’s water resources.

In addition to the stormwater inventory work described in Section 3.4.2, a study of stream phosphorus concentrations was performed to identify sub-watersheds and land uses contributing disproportionate amounts of phosphorus to surface waters. Due to repeated closings of some of Colchester’s beaches and chronically elevated bacteria levels in certain streams, a bacteria source tracking study was also performed in cooperation with the University of New Hampshire. The phosphorus study indicated that streams draining watersheds dominated by agricultural or higher density residential land tend to have elevated phosphorus concentrations

7 Phase I Stream Geomorphic Assessment Report for Smith Creek and Pond Brook. Prepared by Fitzgerald Environmental Associates,

LLC for the Chittenden County Regional Planning Commission, July 29, 2007. 8 Details of this project and its results are available from the Town’s website at http://colchestervt.gov/225/Integrated-

WaterResources-Management.



relative to streams that drain undeveloped, forested land. Near the densely developed Exit 16 I-89 interchange, stream water quality was relatively good despite the watershed being composed of nearly 40% impervious surface. Here, stormwater treatment practices, natural wetlands and ponds, and other natural buffers were effective in maintaining water quality in a portion of the Sunderland Brook watershed.

In 2012-2013, the science and analyses developed in earlier years were applied to develop management program options, with particular regard to improving and targeting the Town’s existing stormwater and onsite wastewater management activities. This work demonstrated that a town-wide stormwater utility may be the most feasible means of addressing the Town’s most critical sources of sediment and phosphorus to local streams and Lake Champlain. Colchester’s new town-wide stormwater utility was approved in April 2017.

3.2.3 2015 Northern Lake Champlain Direct Drainages (Basin 5) Tactical Basin Plan

Tactical basin plans are completed by DEC watershed planners, and focus on projects or actions needed to protect or restore specific waters and identify appropriate funding sources to complete the work, based on monitoring and assessment data. Since these tactical plans guide all watershed work supported by DEC’s Watershed Management Division, the issues identified in the plans are the ones prioritized for management attention, including funding. Tactical Basin Plans integrate priority items from complementary plans, including River Corridor Plans, Stormwater Master Plans, Backroads Inventories, and Agricultural Environmental Assessments.

The most recent Tactical Basin Plan for Basin 59 was reviewed, with particular attention to identification of any priority issues within the project area that may include a Town-infrastructure related source or impact. Two high-priority issues were identified that may partly be attributed to Town roadway infrastructure:

Identify and implement needed Better Backroads BMPs for roads identified in Appendix B of the Plan (two locations in Stormwater Project area, one of which is a private driveway)

In Crooked Creek adjacent to and downstream of VT Route. 7, address runoff to gullies and stabilize erosion stemming in part from VT Route 7 stormwater runoff.

9 Northern Lake Champlain Direct Drainages Tactical Basin Plan. Vermont DEC Watershed Management Division, August, 2015.

Available online at http://dec.vermont.gov/watershed/map/basin-planning/basin5



3.2.4 2016 Malletts Bay Initiative

In 2015-2016, the Town undertook a planning effort to engage the community in refining the vision for the West Lakeshore Drive corridor along the southern shore of Malletts Bay10. The Planning Commission worked with staff and consultants to take community input and craft draft zoning language for the area that implements the community's vision for the Bay. Building upon the foundation of prior planning efforts and guided by input received at public workshops, standards were drafted for new zoning that includes requirements for flood-proofing and flood resilience, green stormwater infrastructure, and pedestrian/bicycle amenities. The new zoning was approved in August 2016.

3.2.5 2017 All-Hazards Mitigation Plan

From mid-2015 through mid-2017, the CCRPC worked with the Town to update its All-Hazards Mitigation Plan and obtain approval from FEMA Region One. The Town identified Severe Rainstorms, Water Pollution and Fluvial Erosion as the hazards to which the Town was most vulnerable. These vulnerabilities include “damage to new/existing public infrastructure and buildings; temporary road and bridge closures; temporary isolation of vulnerable individuals, and budgetary impacts.” To mitigate the effects of these hazards the Plan includes key actions consistent with this Study including “Action A-4: Annual Upgrades to Stormwater Infrastructure” and “Action B-2: Begin Implementation of Phosphorous Control Plan.”

Existing Roadway Drainage System

3.3.1 Sub-Basin Delineations

Sub-basin delineations were completed to determine the extent of the land areas that contribute stormwater runoff to each Town-owned roadway drainage system within the project area (Figure 5). For upland areas draining to a stormwater outfall, the individual catchments for each defined drainage network were delineated using Geographic Information Systems (GIS) and PCSWMM watershed delineation methods, followed by manual adjustment and field confirmation where necessary. In cases where no outfall exists but overland drainage reaches East and West Lakeshore Drive, the area ultimately draining to the roadway was delineated. Where closed drainage infrastructure exists, but no stormwater outfall, drainage areas were still delineated, but the discharge type is noted as being to groundwater rather than to surface water. Examples of this type of system include the closed roadway drainage systems along Julie and Jeffrey Drives in the Smith Creek watershed (Figure 5). Sub-basins are generally numbered from west to east along Lakeshore Drive where drainage is to Malletts Bay, and from downstream to upstream in the Moorings Stream, Crooked Creek, and Smith Hollow Creek watersheds.

10 Detailed information about the Malletts Bay Initiative is available at http://colchestervt.gov/608/Malletts-Bay-Initiative.



Figure 5: Sub-Basin Delineations for Transportation Related Drainage Systems



3.3.2 Stormwater Infrastructure Inventory

A stormwater data inventory was conducted during the 2009 field season for the Town of Colchester’s part of the Integrated Water Resource Management Plan (Section 3.3.2). The inventory included comprehensive field data collection of both municipal and private (where permission was granted) stormwater infrastructure, as well as a review of stormwater discharge permits required by the Vermont Department of Environmental Conservation (DEC) and associated site plans. Additionally, site plans for developed areas within the town that were not associated with stormwater permits were reviewed.

The resulting databases developed included a GIS inventory of stormwater structures, general locations of site plans with and without stormwater discharge permits and locations of stormwater easements. All stormwater discharge permits, site plans, easement documents, and co-applicant maintenance agreements associated with properties within the Town of Colchester were digitally catalogued and associated with a spatial location, where possible.

Stormwater infrastructure and permit data located within the project area were extracted from the Town-wide dataset and were updated during this project to include infrastructure built or modified since the inventory was initially completed, and to include key elevation data for modeling (rim elevations, pipe diameters where missing, invert depths and elevations, etc.). The map created from this inventory is shown in Figure 6.



Figure 6: Stormwater Infrastructure Inventory



3.3.3 Lakeshore Drive Drainage Observations and Outfall Inspections

Prior to developing recommendations related to any potential improvements within the project area or considering new projects, it was necessary to evaluate the condition of the current closed drainage system, its tributary area, and the outfalls along the lakeshore. The following sections describe this evaluation and provide a discussion of observed challenges along West and East Lakeshore Drives.

3.3.3.1 Lakeshore Drive Existing Drainage Observations

Existing drainage problems along West and East Lakeshore Drives, as observed during many rainfall events, were documented in a series of site visits and windshield surveys performed in April 2017. The areas where existing drainage issues were identified are shown on Figure 7, and fell into the following categories:

1. Ponding

2. Green belt too narrow

3. Grade is too flat

4. Runoff is directed over steep embankment

5. Inadequate number or spacing of catch basins

6. Surface runoff is directed into street

7. Poor infiltration

8. Lack of curbline flow

The specifics of these drainage observations, supplemented by examples with photographs, are included in the Appendix.

3.3.3.2 Lakeshore Drive Stormwater Outfall Assessment

To provide a full picture of the existing drainage problems along West and East Lakeshore Drive, it was necessary to locate and evaluate the existing outfalls to Malletts Bay. The objective was to locate the outfalls, verify the pipe size and material, and document the physical condition of the outfall. The investigation covered the area from the intersection of Prim Road and West Lakeshore Drive east to Bay Road. In most cases, these outfalls are located on private property. Site visits to the outfalls were completed in late June after the lake level had dropped so the outfalls were visible; the lake stage was approximately El. 97.0’.

The locations of the outfalls as designated by the ID are shown on Figure 7. Descriptions of each outfall, its condition, and any repair or maintenance needs discovered are included in the Appendix. Several outfalls were found to be in marginal condition, or otherwise in need of further evaluation. Key findings from the outfall evaluation are highlighted below.



West Lakeshore Drive:

MB-01, Outfall O_41: Outlet pipe is in fair condition, but outfall is surcharged and outfall area needs to be cleaned and stabilized, and the ditch extended downstream to daylight.

MB-02, Outfall O_40: Outlet pipe is in good condition but extends out of the embankment; the discharge area has washed out and requires stabilization. Equipment access for repair will require extensive clearing.

MS-01, Outfall OF1: Outlet of the Moorings Stream drainage area, drains into large cast-in-place concrete structure before discharge. Sediment removal is provided in this long tank and access manholes are provided on top for cleaning. Chambers are often submerged and thus often cannot be cleaned.

MB-03, Outfall O_47: Constructed in 2011, in good condition but additional stone fill is needed below outfall pipe to stabilize the conveyance to Malletts Bay.

East Lakeshore Drive:

MB-05, Outfall O_24: Embankment is eroded and portions of outlet pipeline are exposed. If repairs or maintenance are needed they must be completed during low lake level conditions, so the pipe can be accessed from the beach area.

MB-07, Outfall OF3: Outlet for existing system was not found; embankment adjacent to western-most catch basin is substantially eroded where flow from catch basin appears to be directed.

MB-08, Outfall O_32: Outlet pipe is in satisfactory condition; concrete splash pad reduces erosion of the beach when the lake levels are lower. This drainage system could be connected to MB-09/outfall O_33, and outfall O_32 can be abandoned.

MB-15, Outfall O_37: Only pipe found in outfall vicinity was a broken 12-inch AC pipe that was running over the ground surface; upgrade required if this outfall is used to address existing drainage problems.



Figure 7: Lakeshore Drive Existing Drainage Observations and Outfall Assessment



3.3.4 Hydrologic / Hydraulic Assessment of Selected Sub-Basins and Drainage Systems

Following delineation of drainage areas for the Town’s roadway drainage systems, and field assessment and confirmation of existing stormwater infrastructure, a more detailed evaluation of drainage capacity and suitability was completed for a select sub-set of the systems.

A combination of modeling tools was selected to complete hydrologic/hydraulic assessments. Along East and West Lakeshore Drives, the PCSWMM modeling package was selected to allow modeling of multiple closed drainage systems simultaneously. In the upland watersheds, HydroCAD models were developed for two individual drainage systems where the stormwater inventory, windshield surveys, or other data sources indicated the potential for an issue warranting more detailed investigation. The assessment results are briefly described below.

3.3.4.1 Malletts Bay Direct Drainage

Areas contributing drainage to East and West Lakeshore Drives and associated roadway drainage systems (Figure 7) were modeled in PCSWMM wherever the stormwater infrastructure inventory contained adequate information to support model construction. Design storms modeled were SCS Type II 24-hr storms, for return frequencies of the 90% or Water Quality storm (1 inch), 1-year (2.1 inch), 2 year (2.3 inch), 10-year (3.2 inch), and 100-yr (5.3 inch) storms. Infiltration characteristics were assigned to model subcatchments based on the underlying HSG and soil texture, and impervious cover was determined by subcatchment using the Town’s impervious cover dataset.

Key results of this evaluation are summarized in Table 2.



Table 2: Summary of Existing Roadway Drainage System Conveyance Capacity (East and West Lakeshore Drive)

Sub-Basin

ID Street Name(s)

Drainage Area

(acres)

% Impervious

Discharge Type

Outfall ID Existing System

Capacity Limitations

MB-01 West Lakeshore Dr 13.1 19 Surface Water O_41 Most CBs flood briefly at 10-yr storm

MB-02 West Lakeshore Dr 18.1 24 Surface Water O_40 Most CBs flood briefly at 10-yr storm

MB-03 West Lakeshore Dr 6.4 30 Surface Water O_47 No flooding or surcharge at 100-yr storm

MS-01 West Lakeshore Dr 16.5 30 Overland Flow; Surface Water

511 E Lakeshore culvert and OF1

Insufficient information to model majority of area – very limited drainage infrastructure present

MB-04 West Lakeshore Dr East Lakeshore Dr

3.5 49 Groundwater No stormlines to model; Poor infiltration from existing CBs and drywells

MB-05 East Lakeshore Dr 17.3 10 Surface Water O_24 No flooding or surcharge at 100-yr storm

MB-07 East Lakeshore Dr 5.1 34 Surface Water OF3 CBs flood and surcharge at 2-yr storm

MB-08 East Lakeshore Dr 9.6 17 Surface Water O_32 CBs flood and surcharge at 100-yr storm

MB-09 East Lakeshore Dr Williams Rd

11.2 34 Surface Water O_33

CBs on Williams Rd and/or 12” stormlines flood and surcharge at 10-yr storm

MB-11 East Lakeshore Dr Rea Janet Dr Suncrest Terr

33.7 12 Surface Water O_36 Insufficient information to model

MB-15 East Lakeshore Dr 0.8 31 Surface Water O_37 No flooding or surcharge at 100-yr storm

MB-16 East Lakeshore Dr 22.2 8 Surface Water O_38

Insufficient information to model; Private drainage system and detention basin at Bay Ride Estates is State-permitted

MB-17 East Lakeshore Dr 16.3 6 Surface Water O_35 Insufficient information to model

MB-18 East Lakeshore Dr 11.4 21 Surface Water O_34 Both CBs surcharge briefly in 100-yr storm



3.3.4.2 Smith Creek

Drainage area SC-08 was modeled to more closely assess the potential contributions to and causes of the gully noted in previous stream geomorphic assessments (Section 3.2.1), and to assess whether the 18” cross culvert conveying runoff from I-89 across Williams Road constitutes a critical hydraulic restriction in the system. This drainage area is 39.2 acres and while the area near Williams Road is underlain by well-drained sands, much of the area within and up-slope of the I-89 corridor is underlain by poorly drained (HSG D) soils.

The existing culvert is severely undersized. The model is showing overtopping of the road for the 10- and 100-year storms, by approximately one inch and three inches, respectively. The modeling indicates that a 36-inch diameter pipe would be adequate to pass the 100-year storm, with the stage during that event at a similar elevation to the crest of the road. Culvert diameters for the I-89 drainage systems support this evaluation result; the culvert passing under I-89 NB is 24-inch diameter, while the culvert passing beneath I-89 SB is 30-inch diameter.

3.3.4.3 Crooked Hollow Creek

Two drainage areas in the Country Meadows development on Orchard Drive (CC-05 and CC-06) were modeled to characterize the range of untreated stormwater flows currently discharging to Crooked Hollow Creek via outfall O_12. Drainage area CC-06, with a total area of 7.2 acres, is primarily underlain by poorly drained soils, with the closed drainage system serving this portion of the development drains to a dry detention/infiltration basin (Figure 6 and Figure 9). Overflow from the CC-06 basin is directed into the closed drainage system for area CC-05 during larger storms. The CC-05 drainage area is larger (17.3 acres) and primarily underlain by sandy soils. Runoff reaching the CC-05 closed drainage system is currently conveyed to outfall O_19 without treatment. Modeling of the closed drainage system indicates that it is adequate to convey design storms up to the 100-year, 24-hour storm. Modeled peak flows and runoff volumes at the main 30-inch reinforced concrete pipe outfall to Crooked Hollow Creek are 4 cubic feet per second (cfs) / 14,300 cf for the 2-year storm, 5 cfs / 51,700 cfs for the 10-year storm, and 42 cfs / 124,900 cf for the 100-year storm.



Figure 8: Williams Road Cross Culvert Subwatershed Mapping



Figure 9: Country Meadows Subwatershed Mapping



Existing Roadway Drainage and Stormwater Systems Summary Key characteristics and assessment results for each identified Town roadway drainage system within the project area are summarized in Table 3 and Figure 10. Detailed descriptions of existing roadway drainage areas and stormwater management systems are included in the Appendix.

Approximately 16% of the total area of interest (562 acres of the total watershed area of 3,440 acres) drains to one of the 49 Town roadway drainage systems identified during this project. Of the Town roadway drainage system land areas, runoff from 139 acres (25%) is presently treated using green stormwater infrastructure. In a few cases (such as sub-basin SC-04), this “green” infrastructure consists of recently-constructed bioswales, rooftop disconnection, and infiltration-based practices that fully comply with the requirements and standards of the 2002 Vermont Stormwater Management Manual. In many instances, the existing stormwater management systems function as “green” infrastructure but consist of infiltrating catch-basins, perforated stormline, or other less visible practices (for example, in sub-basins SC-05 and SC-07). Runoff from an additional 134 acres (24%) of the land area draining to Town roadway drainage systems receives some level of water quality treatment before discharging to a stream or to Malletts Bay, but this treatment is provided by practices such as dry extended detention ponds or grass channels (for example, in much of the Moorings Stream watershed), which are no longer considered to provide full water quality treatment under the 2017 Vermont Stormwater Management Manual. Stormwater runoff from the remaining 290 acres (52%) currently discharges to project area streams or Malletts Bay without receiving water quality treatment.

The following characteristics are included in the Appendix for each Town roadway drainage system within the project area:

Sub-Basin ID (as described in Section 3.3.1 and shown on Figure 5)

Road Name(s)

Drainage area characteristics:

o Primary Hydrologic Soil Group (HSG), as derived from the Chittenden County Soil Survey for the drainage area

o Total drainage area (acres)

o Breakdown of impervious surfaces within the drainage area, including paved and gravel road/driveway impervious, as well as building impervious (in acres) draining to the Town roadway drainage system

o Percent impervious cover in the drainage area



o Estimated Water Quality Volume (WQv) (acre-feet), based on the 2017 VSMM Water Quality Treatment Standard’s required runoff capture and treatment depth of 1 inch11

o Estimated Total Phosphorus Load (lbs/year) for the WQv, calculated using the Simple Method approach and based on phosphorus loading rates for developed lands and transportation developed by Vermont DEC in 2015 as an interim procedure to guide applicants in meeting phosphorus “Net Zero” requirements for projects that would potentially discharge phosphorus to Lake Champlain before the P TMDL was in place12. The average annual pollutant (phosphorus) concentrations provided in the guidance are 0.441 mg/L for developed lands, 0.237 mg/L for paved roads, and 0.618 mg/L for unpaved roads. The developed lands concentration of 0.441 mg/L was applied for most systems in the project area, consistent with DEC guidance for systems that include driveways, access drives, and other transportation surfaces within larger development projects (e.g., residential and commercial subdivisions). For a few large and mostly undeveloped drainage areas)

Stormwater infrastructure summary characteristics:

o Drainage system type (open or closed drainage)

o Operational permit or site plan (if an operational stormwater permit has been issued by Vermont DEC for the system, or if no permit was issued but the stormwater infrastructure inventory includes a site plan for the drainage system)

o Water quality treatment practices designed and implemented for treatment of runoff, if any

o Discharge type, whether the drainage system has an outfall draining to a stream or to Malletts Bay, or discharges to groundwater via

11 2017 Vermont Stormwater Management Manual Rule and Design Guidance, effective July 1, 2017. Available at

http://dec.vermont.gov/sites/dec/files/wsm/stormwater/docs/Permitinformation/2017%20VSMM_Rule_and_Design_Guidance_04172017.pdf

12 Vermont DEC, Stormwater Program Guidance for Meeting Phosphorus “Net Zero” Requirements pursuant to the Department’s “Interim Procedure for Discharges of Phosphorus to Lake Champlain and Waters that Contribute to the Impairment of Lake Champlain. “ November 24, 2015. Available at http://dec.vermont.gov/sites/dec/files/wsm/stormwater/docs/MainPage/sw_guidance_to_meet_net_zero_p.pdf.



infiltrating catchbasins, infiltration basins, subsurface trenches, drywells, or other means

o Determination regarding the adequacy of stormline slope and capacity, where evaluated

o System age, in years from 2017, either as determined from permits and site plans, or as approximated based on the age of surrounding development as recorded in the Colchester Assessor’s database13

o Overall system condition and condition highlights, if any

o Summary of condition of the system’s outfall / outlet, as well as highlights of any erosion or sedimentation issues encountered

o A preliminary assessment of whether the existing system meets current or anticipated local and State standards, including those of the forthcoming Municipal Roads General Permit, the anticipated Developed Lands General Permit (for “3-acre sites”), and the current Vermont Stormwater Management Manual Rule, where applicable

Figure 10: Summary of Existing Water Quality Treatment Status for Town Roadway Drainage Areas

13 The Colchester Assessor’s database is available at http://colchestervt.gov/629/GIS-Map-Assessment-Data.


39 Resources Assessment

Table 3: Sub-Basin Assessment Summary



4 Resources Assessment A preliminary review of natural and cultural resources in the project study area was conducted and is discussed in this chapter. This assessment was completed with the purpose of identifying the presence and extent of natural and cultural resources and their constraints within the Malletts Bay study area.



Cultural Resources Between 2000 and 2004, Hartgen Archeological Associates, Inc. (HAA) and the University of Vermont Consulting Archeology Program (UVM CAP) conducted several surveys and site evaluations along West Lakeshore Drive. These studies were done to evaluate the potential archeological impacts of a sidewalk along the south side of West Lakeshore Drive which was being proposed at the time. The entire corridor was surveyed and tested in order to find any precontact artifacts. HAA led the first two phases of the evaluation and identified and excavated two prehistoric Native American locations of significance. These two areas are the Norbert property (VT-CH-942) and the Shore Acres Drive site (VT-CH-943). These sites are shown in Figure 11 which is taken from the 2003 HAA End of Fieldwork Letter14. At these sites, various artifacts, including prehistoric tools and pottery, from the Late Woodland period were found. In the second phases conducted by HAA, the Norbert site and portions of the Shore Acres Drive site were determined to be eligible for the National Register of Historic Places. Due to that project falling under the jurisdiction of the U.S. Army Corps of Engineers (ACOE), a third phase, data recovery, was completed by UVM CAP to mitigate adverse effects of the sidewalk project on the sites and to comply with Section 106 of the National Historic Preservation Act of 1966, as amended15.

Natural Resources A review of natural resources within the project area was conducted and an overview is provided below. This review was conducted using the Vermont Agency of Natural Resources (ANR) Online Natural Resources Atlas16. A map showing the locations of these resources is provided in Figure 12.

Streams: Many streams are located within the project area with one crossing across West Lakeshore Drive and three crossings across East Lakeshore Drive flowing directly into Malletts Bay. Other streams exist in various wooded areas and neighborhoods throughout the project area, both east and west of Interstate 89.

Impaired Water: Malletts Bay is identified as an impaired feature of Lake Champlain. The Winooski River watershed is an impaired watershed and this falls in the southern part of the project area.

14 Jamison, T. R., Pd.D. Phase I and II Archeological Investigations West Lakeshore Drive Path End-of-Fieldwork Letter [Letter to Tyler

Hart]. Colchester, VT. 10 December 2003. 15 Knight, C., Ph.D. End-of-Field Letter for Phase III Data Recovery at the Norbert (VT-CH-942) and Shore Acres Drive (VT-CH-943)

sites, located in the proposed West Lakeview Drive Path project area [Letter to Tyler Hart]. Colchester, VT. 24 May 2004. 16 Vermont Natural Resource Atlas, Vermont Agency of Natural Resources, http://anrmaps.vermont.gov/websites/anra5/, Queried 13

December, 2016.



Wetlands: Various Class 2 wetlands exist throughout the project area. There is a wetland on West Lakeshore Drive near the Bay Harbor Marina and extending south past Jakes Place and into the adjacent wooded area.

Soils: The majority of the roadway corridor contains prime agricultural soil but there are statewide and statewide (b) soils along the corridor as well. The westernmost 0.25 miles of West Lakeshore Drive contains statewide soils. Statewide (b) soil existing in the ROW in front of Moorings Marina.

Hazardous Waste Sites:

Numerous hazardous sites exist along West Lakeshore Drive including the marinas, Mike’s Auto Parts, the Hazelett Strip-Casting Corporation, a dentist’s office, and a veterinary hospital.



Figure 11: Identified and Excavated National Historic Sites



Figure 12: Natural Resources Map



Figure 11 continued


47 Meetings & Public Outreach

5 Meetings & Public Outreach This project directly affects many stakeholders including residents and business owners, commuters through the area, and visitors to Malletts Bay, so it is critical to the success of this project that their opinions be considered. The Public Outreach Plan was designed using the guidelines provided by the CCRPC’s Public Participation Plan and Equity Impact Worksheet. This project included an initial Local Concerns Meeting, online survey, and two later public meetings to present the alternatives and eventually select a preferred alternative. This chapter summarizes the opportunities and concerns identified through this process.



Public Meetings The Outreach Plan for this project involved three meetings which were open to the public:

Local Concerns Meeting (January 19, 2017)

Public and Selectboard Meeting #1 (September 26, 2017)

Public and Selectboard Meeting #2 (October 10, 2017)

Meeting outreach materials, presentations, and meeting notes can be found in the Appendix.

The following opportunities and concerns were received during the public input process:

Opportunities

Bicycle and Pedestrian Improvements

Traffic calming will improve safety for all users

Shared use path on the south side of the road seems ideal

Bayside Intersection Improvements

Make the beach, park, and bay a show piece for the area

Reroute East Lakeshore Drive away from the lake

Stormwater Management

Use infiltration where soils allow this as an option

Colchester’s local options tax may contribute to stormwater projects

Concerns

Bicycle and Pedestrian Improvements

Safety of bicyclists and pedestrians coexisting on a shared use path

Poor access management creates hazards for sidewalk users

Bayside Intersection Improvements

Pedestrian and bicycle safety in a roundabout

Minimize impervious surfaces

Stormwater Management

Impacts of state and federal clean water legislation

Coordination with Malletts Bay sewer project and other projects



Online Survey An online survey was created and distributed to the public to gather feedback from all residents, not just those who attended the public meetings. This survey was used to present the alternatives to a wider audience and foster a spirit of inclusivity so that all could participate in the alternatives selection process. In total, there were 102 respondents to the survey. Of these 102 participants, 42 lived within the project area, 55 lived out of the project area but within Colchester, and 5 were from outside of Colchester. The survey showed that there were similar sentiments towards the bike lanes and shared use path. In reference to the intersection, the roundabout and realignment of East Lakeshore Road were the clear favorites. The general conclusion around stormwater is that standards should be met in all watersheds but exceeding should be attempted in areas where it is more cost effective. A full summary of results can be found in the Appendix.


50 Planning & Design Criteria

6 Planning and Design Criteria The planning and design criteria identified in this chapter provide a basis for design and a means of evaluation of the stormwater, bicycle/pedestrian, and intersection alternatives. These criteria come from a variety of standards, including the Colchester Public Works Standards and Specifications, the Vermont Agency of Natural Resources and Transportation, and the Vermont Pedestrian and Bicycle Facility and Design Guide.



Transportation Alternatives Design Criteria The design criteria used to evaluate the build alternatives for the multi-modal improvements along West Lakeshore Drive are shown in Table 4 and the criteria for the Bayside intersection improvements are shown in Table 5. The design criteria comes from a variety of standards including the Town of Colchester’s Department of Public Works Specifications and Standards, A Policy on Geometric Design of Highways and Streets, VTrans State Design Standards, and others.



Table 4: West Lakeshore Drive Bicycle & Pedestrian Improvements Design Criteria

Design Element West Lakeshore Drive Standard Reference

AADT (2016) 13,952

Between Prim Rd and Coates Island

Functional Class Minor Arterial

Posted Speed Limit 25 mph

Minimum Stopping Sight Distance 155 feet (1)

Lane Width (2)

Minimum 11 feet

Existing 11 feet

Paved Shoulder Width (2)

Minimum 2-4 feet

Existing 1-4 feet

Planting Strip Width (2)

Minimum 7 feet

Existing 0-5 feet

Sidewalk Width (2)

Minimum 5 feet

Existing 5 feet

Shared Use Path Width Minimum: 10 feet (2)

Rectangular Rapid Flashing Beacons (RRFB) at Crosswalks

(1) AADT between 3,000-9,000 AND posted speed ≥40 mph (2) AADT >9,000 AND posted speed ≥30 mph (3) Crosswalk is deemed “unduly hazardous” by Director of Public Works,

Town Engineer, and Chief of Police (4) Crosswalk serves many school, elderly housing, or family recreation

area pedestrians AND speed ≥30 mph OR AADT>2,000 (5) Documented vehicle crash history in direct conflict with pedestrians

(3)

*Shortest sight distance at midblock crossings

(1) A Policy on Geometric Design of Highways and Streets, 6th Ed. American Association of State Highways and Transportation Officials, Washington, DC. 2011.

(2) Colchester Public Works Specifications and Standards. Town of Colchester, April 2012.

(3) Dubin, Chris. Memo to Osborne, Bryan K. Re: Colchester Crosswalk Assessment and RRFB Warrant Analysis. 27 April 2015.



Table 5: Intersection Improvement Design Criteria

Design Element W Lakeshore

Drive E Lakeshore

Drive Blakely Road Bayside Park Standard

Reference

Approach AADT (2016)

13,952 Between Prim Rd and Coates Island

6,331 Between S Bay Cir and Williams Rd

10,445 Between E/W

Lakeshore Dr and Laker Ln

--

Functional Class Minor Arterial Major Collector Minor Arterial --

Posted Speed Limit 25 mph 30 mph 35 mph --

Design Vehicle WB-62 WB-62 WB-62 -- (1)

Roundabout Urban Single-Lane (2)

Inscribed Diameter Minimum: 115 feet (2)

Entry Width 14-16 feet (2)

Entry Radius 33-98 feet (2)

Exit Radius Minimum: 50 feet (2)

Stopping Sight Distance

155 feet (3)

(1) Colchester Public Works Specifications and Standards. Town of Colchester, April 2012.

(2) Roundabouts: An Informational Guide. US Department of Transportation, Federal Highway Administration, 2010.

(3) A Policy on Geometric Design of Highways and Streets, 6th Ed. American Association of State Highways and Transportation Officials, Washington, DC. 2011.



Stormwater Alternatives Design Criteria The following planning and design criteria set the performance standards and provide guiding principles for the work completed during Stormwater Infrastructure Assessment, Sub-Basin Delineation, Watershed Description, and Hydrologic Analysis, and Alternatives Development. These criteria generally take into account the Town’s goals; existing and anticipated specifications, standards, and regulations; and input received from the public during the Local Concerns Meeting. A list of key design criteria and standards can be found in Table 6. A full discussion of planning and design criteria for the stormwater management system is included in the Appendix.



Table 6: Stormwater Management System Design Criteria

Design Element Criteria Standard Reference

Watersheds Applied

All Water Quality Best Management Practices (BMPs)

Treatment volume Sufficient to capture and treat 1.0 inches of runoff from drainage area

(1) All watersheds in project area

Surface Bioswale Minimum width 7 feet (2) Malletts Bay – West

Lakeshore Drive Malletts Bay – East Lakeshore Drive Crooked Hollow Creek Smith Creek

Bioretention soil mix media minimum depth

2 feet (1)

Pea gravel choker course depth 0.25 feet (1) Gravel reservoir minimum depth 0.75 feet (1)

Ponding depth 1 foot (1)

Bioretention Area Minimum width 7 feet (2)

Malletts Bay – East Lakeshore Drive Crooked Hollow Creek Smith Creek

Bioretention soil mix media minimum depth

2 feet (1)

Pea gravel choker course depth 0.25 feet (1) Stone reservoir minimum depth 0.75 feet (1) Ponding depth 1 foot (1) Subsurface Infiltration Trench Stone reservoir minimum width 4 feet (1)

Malletts Bay – East Lakeshore Drive

Stone reservoir minimum depth 4 feet (1)

Perforated distribution pipe 0.66 feet diameter (8 inches) in top 1 foot of stone reservoir

(1)

Subsurface Infiltration Chamber

Infiltration Chamber Make/Model Applied

Stormtech ADS – SC-310 (1) Malletts Bay – West Lakeshore Drive Smith Creek

Gravel Wetland Treatment cell minimum width 5 feet (1)

Malletts Bay – West Lakeshore Drive Moorings Stream

Gravel treatment area depth 3 feet (1)

Ponding depth above gravel in swale 0.5 feet (3:1 side slopes and 0.5 feet freeboard)

(1)

Perforated distribution pipe 0.66 feet diameter (8 inches) in top 1 foot of stone reservoir

(1)

(1) 2017 Vermont Stormwater Management Manual Rule and Design Guidance. Vermont Agency of Natural Resources, July 2017. (2) Colchester Public Works Specifications and Standards. Town of Colchester, April 2013.


56 Alternatives Analysis

7 Alternatives Analysis An alternatives analysis was conducted for both the stormwater and the transportation aspects of this scoping study. The alternatives for the Bayside intersection consist of operational changes to the existing signal, geometric changes to the existing intersection, the construction of a roundabout, and the closure of the East Lakeshore Drive approach with and without a parallel connection to Blakely Road. The West Lakeshore Drive alternatives include bike lanes, a shared use path, and several additional alternative “add-ons”. The stormwater alternatives evaluate packages of improvement that either meet water quality standards or exceed these standards. These alternatives were produced using a combination of the Town’s needs, public input, and engineering judgement. A description of the analysis and evaluation matricies are provided in this chapter.



Lakeshore Drive and Blakely Road Intersection Alternatives Six scenarios were modelled as part of the intersection scoping study. In this modelling process, intersection movements and approaches are evaluated using the metric of Level of Service. Level of Service (LOS): LOS, is a standard measure of operational effectiveness for transportation facilities. LOS is defined by the Highway Capacity Manual, published by the Transportation Research Board. LOS is graded from LOS A (free flow conditions) to LOS F (congested conditions). For signalized intersections, it is based on the estimated average vehicle delay for all traffic at the intersection. LOS A represents little to no delay, or uncongested conditions, whereas LOS F indicates very congested conditions with long delays. In urbanized areas, overall LOS D or better is generally considered acceptable during the peak hours. LOS E conditions indicate an intersection that is operating at or near peak capacity, while intersections operation at LOS F cannot effectively serve peak demand. LOS D is the threshold for acceptance used in this study.

7.1.1 Intersection Alternative I – No Build

The first alternative is the No Build alternative, which was evaluated in the future years of 2027 and 2037. The most up to date count data available (June 2014) was obtained in order to quantify the existing conditions. No adjustments were made to the June 2014 count data as traffic volumes have not changed significantly between 2014 and 2016 and June volumes most likely represent the peak yearly volumes. Traffic volume adjustments were applied in order to balance traffic volumes between the East/West Lakeshore Drive and Laker Lane intersections. Yearly growth factors were calculated by VTrans and have been published in the 2015 Redbook17. These growth factors are based on research developed by Vermont economic and labor statistics. The results from the congestion analysis are shown in Table 7. The Appendix includes additional information including traffic volumes and the full capacity analysis results.

17 Continuous Traffic Counter Report (The Redbook) Based on 2015 Traffic Data. Vermont Agency of Transportation, Traffic Research

Unit. Vermont, September 2016.



Table 7: Intersection Capacity Analysis Summary – Alternative I

A summary of the No Build intersection capacity analyses is as follows:

The Level of Service (LOS) is expected to worsen between 2027 and 2037 during the weekday evening peak hour at the Bayside intersection; decreasing from LOS D to F.

The volume-to-capacity ratio exceeds saturation conditions of 0.9 at the Bayside intersection for the weekday evening peak hour in both 2027 and 2037. The volume to capacity ratio at the Blakely Road / Laker Lane intersection never exceeds saturation conditions.

The Bayside operates at unacceptable levels of service during the 2037 evening peak hour.

The Blakely Road at Laker Lane eastbound approach operates at unacceptable levels of service during both AM and PM peak hour conditions.

7.1.2 Intersection Alternative II (A) – Operational Modifications

The second alternative involves the improvement of the intersection without any changes to the roadway geometry. Operational modifications refer to the optimizing of the existing signal and upgrading the pedestrian crossing signals. The results of the Level of Service and Capacity Analysis are shown Table 8 includes optimizing

Intersection Peak Hour Approach v/c* Delay** LOS*** v/c Delay LOS

Overall 0.76 20.9 C 0.80 23.0 C

Overall 0.91 51.2 D 0.97 81.4 F

EB 0.59 36.2 E 0.84 76.4 F

NB Left 0.18 9.7 A 0.21 10.3 B

NB Thru 0.19 0 - 0.21 0 -

SB Thru 0.36 0 - 0.4 0 -

SB Right 0.11 0 - 0.12 0 -

EB 0.23 36 E 0.36 53.7 F

NB Left 0.02 9.1 A 0.02 9.5 A

NB Thru 0.47 0 - 0.51 0 -

SB Thru 0.39 0 - 0.43 0 -

SB Right 0.01 0 - 0.01 0 -

* Volume to capacity ratio** Delay expressed in seconds per vehicle*** Level of service

Blakely Rd at East and West Lakeshore Dr

(Signalized)

Weekday AM

Blakely Rd at Laker Lane

(Unsignalized)

Weekday PM

2027 No Build 2037 No Build

Weekday AM

Weekday PM



timings and an advanced pedestrian phase at the project intersection. Detailed results of the analyses are shown in the Appendix. A graphic of this alternative can be found in Figure 13.

Figure 13: Intersection Alternative II (A)



Table 8: Intersection Capacity Analysis Summary – Alternative II (A)

A summary of the intersection capacity analyses for Alternative II (A) is as follows:

The volume-to-capacity ratio exceeds saturation conditions of 0.9 at the Bayside intersection for the 2027 and 2037 weekday evening peak hour.

The Bayside intersection operates at acceptable levels of service for all years and peak hours.

The Blakely Road at Laker Lane eastbound approach operates at unacceptable levels of service during all conditions except for the 2027 morning peak hour.

Overall, the traffic operations associated with Alternative II (A) are better than the No Build alternative.

7.1.3 Intersection Alternative II (B) – Operational & Geometric Modifications

In addition to the operational modifications included in Alternative II (A), Alternative II (B) proposes two westbound through lanes on Blakely Road which merge back to one lane 250’ west of the intersection. The results of the Level of Service and Capacity Analysis are shown in Table 9. Detailed results of the analyses are shown in the Appendix. Future traffic volumes used in this alternative are the same as Alternative II (A). A graphic of this alternative can be found in Figure 14.


Overall 0.92 13.6 B 0.93 16.2 B

Overall 0.92 17.6 B 0.96 24.2 C

EB 0.57 34.7 D 0.82 72 F

NB Left 0.18 3.3 A 0.21 3.5 B

NB Thru 0.19 0 - 0.21 0 -

SB Thru 0.36 0 - 0.4 0 -

SB Right 0.11 0 - 0.12 0 -

EB 0.27 41.1 E 0.34 49 E

NB Left 0.02 9.3 A 0.02 9.4 A

NB Thru 0.49 0 - 0.51 0 -

SB Thru 0.41 0 - 0.43 0 -

SB Right 0.01 0 - 0.01 0 -* Volume to capacity ratio** Delay expressed in seconds per vehicle*** Level o f service


(Unsignalized)

Weekday AM

Weekday PM

2027 Build 2037 Build


(Signalized)

Weekday AM

Weekday PM



Figure 14: Intersection Alternative II (B)

Table 9: Intersection Capacity Analysis Summary – Alternative II (B)


Overall 0.74 19.7 B 0.78 21.5 C

Overall 0.66 23.8 C 0.68 29.6 C

EB 0.58 35.9 E 0.83 73.7 F

NB Left 0.18 9.7 A 0.21 10.3 B

NB Thru 0.19 0 - 0.21 0 -

SB Thru 0.36 0 - 0.4 0 -

SB Right 0.11 0 - 0.12 0 -

EB 0.23 35.9 E 0.36 53.4 F

NB Left 0.02 9.1 A 0.02 9.5 A

NB Thru 0.47 0 - 0.51 0 -

SB Thru 0.39 0 - 0.43 0 -

SB Right 0.01 0 - 0.01 0 -

* Volume to capacity ratio** Delay expressed in seconds per vehicle*** Level o f service


(Signalized)

Weekday AM

Weekday PM


(Unsignalized)

Weekday AM

Weekday PM




A summary of the intersection capacity analyses for Alternative II (B) is as follows:


The Blakely Road at Laker Lane eastbound approach operates at unacceptable levels of service during all conditions.

Traffic operations operate relatively similar under Alternative II (A) and Alternative II (B), with slightly shorter delays for Alternative II (A).

Overall, the traffic operations associated with Alternative II (B) are better than during the No Build alternative.

7.1.4 Intersection Alternative III – Roundabout

A roundabout was examined as the third alternative for the Lakeshore Drive and Blakely Road intersection. The roundabout size and arrangement is based on existing data such as traffic volumes and available space for construction. The results of the roundabout capacity summary are shown in

Table 10. Detailed results of the analyses are shown in the Appendix. A graphic of the roundabout alternative can be found in Figure 15. The roundabout design assumes the following configuration:

Inscribed Diameter: 130 feet

Circulating Roadway Width: 20 feet

Central Island: 90 feet diameter, Raised/Mountable

Entry Lanes: 1 per approach

Entry Lane Width: 20 feet

Entry Radius: W Lakeshore Dr and Blakely Rd – 35 feet

E Lakeshore Dr – 50 feet

Bayside Park – 33 feet



Figure 15: Intersection Alternative III

Table 10: Intersection Capacity Analysis Summary – Alternative III

Intersection Approach Peak Hour v/c* Delay** LOS*** v/c Delay LOS

EB 0.54 1.9 A 0.60 2.0 A

WB 0.31 4.0 A 0.35 4.1 A

NB 0.06 5.0 A 0.07 6.2 A

SB 0.29 5.4 A 0.33 5.7 A

EB 0.64 2.5 A 0.44 3.5 A

WB 0.75 8.1 A 0.84 11.4 B

NB 0.08 7.0 A 0.06 3.6 A

SB 0.55 11.4 B 0.72 19.5 B

* Volume to capacity ratio

** Delay expressed in seconds per vehicle

*** Level of service


(Roundabout)

Weekday AM

Weekday PM




A summary of the intersection capacity analyses for Alternative III is as follows:

The Blakely Road at Laker Lane intersection is assumed to operate similarly to Alternative II and is not included above.

The volume-to-capacity ratio does not exceed saturation conditions of 0.9 at the Bayside intersection for any evaluation period.


Overall, the traffic operations associated with Alternative III are better than both Alternatives I and II.

7.1.5 Intersection Alternative IV (A) – East Lakeshore Drive Reconfiguration

The fourth alternative being examined in this study incorporates the realignment of East Lakeshore Drive through the Hazelett property. The proposed alignment terminates East Lakeshore Drive approximately 1,000 feet before the intersection with West Lakeshore Drive and Blakely Road and reroutes the roadway to intersect Blakely Road at Laker Lane. This results in a three-way signalized intersection at West Lakeshore Drive and Blakely Road at the Bayside Park entrance and a four-way signalized intersection at Blakely Road and Laker Lane.

Existing turning movements were reassigned to match the proposed alignment with the assumption that 10% of existing traffic would no longer use the realigned East Lakeshore Drive due to the longer end-to-end travel time. The results of the capacity summary are shown in Table 11. A graphic can be found in Figure 16. Detailed results of the analyses are shown in the Appendix.



Figure 16: Intersection Alternative IV (A)



Table 11: Intersection Capacity Analysis Summary – Alternative IV (A)

A summary of the intersection capacity analyses for Alternative IV (A) is as follows:

The volume-to-capacity ratio exceeds saturation conditions of 0.9 at the Blakely Road and Laker Lane intersection for all conditions.

Both intersections operate at acceptable levels of service for all years and peak hours.

Overall, the levels of service associated with Alternative IV (A) are better than the No Build alternative.

7.1.6 Alternative IV (B) – East Lakeshore Drive Dead End

Alternative IV (B) terminates East Lakeshore Drive north of the Bayside intersection with no new alignment through the Hazelett property. In this alternative, East Lakeshore Drive would continue to a cul-de-sac and parking area at the expanded Bayside Park.

Existing turning movements were reassigned so that they match the proposed alignment. It is assumed that 10% of the peak hour trips on East Lakeshore Drive are diverted to Williams Road and another 90% to US 2/7, travelling through Severance Corners. The results of the capacity summary for Alternative IV (B) are shown in Table 12. A graphic of this alternative is shown in Figure 17. Detailed results of the analyses are shown in the Appendix.


Overall 0.72 5.0 A 0.80 5.4 A

Overall 0.80 5.5 A 0.85 6.3 A

Overall 1.11 16.1 B 1.08 8.7 A

Overall 1.00 19.1 B 0.98 23.0 C


** Delay expressed in seconds per vehicle*** Level o f service

Weekday PM

Weekday PM

Blakely Rd at Laker Ln

(Signalized)

Weekday AM


(Signalized)

Weekday AM




Figure 17: Intersection Alternative IV (B)

Table 12: Intersection Capacity Analysis Summary – Alternative IV (B)

Intersection Peak Hour Approach v/c* Delay** LOS*** v/c* Delay** LOS*** v/c Delay LOS

WB 0.26 17.9 C 0.3 17.6 C 0.23 16.1 C

NB Thru/Right 0.19 0 - 0.17 0 - 0.17 0 -

SB Left 0.06 8.0 A

SB Thru 0.05 1.4 A 0.06 1.7 A 0.25 0 -

WB 0.44 28.2 D 0.64 42.5 E 0.46 28.7 D

NB Thru/Right 0.4 0 - 0.4 0 - 0.4 0 -

SB Left 0.10 9.4 A

SB Thru 0.06 1.6 A 0.1 2.5 A 0.28 0 -

Overall 0.91 22.0 C 0.91 22.0 C 0.91 22.0 C

Overall 1.40 73.9 E 1.40 73.9 E 1.40 73.9 E


** Delay expressed in seconds per vehicle

*** Level of service

Blakely Rd at Williams Rd

(Unsignalized)

Weekday AM

Weekday PM

2037 BuildAdditional Turn Lanes

DOES NOT EXIST

2037 BuildDead End E Lakeshore

DOES NOT EXIST

DOES NOT EXIST DOES NOT EXIST

Weekday AM

Blakely Rd and Severance Rd at

US 2/7(Signalized)

Weekday PM

2037 No BuildNo Dead End



A summary of the intersection capacity analyses for Alternative IV (B) is as follows:

The critical year of 2037 is the only time period shown in the table above. Intersections evaluated with this alternative include the Blakely Road intersections with Williams Road and US 2/7 & Severance Road.

The volume-to-capacity ratio exceeds saturation conditions of 0.9 at the Severance Corners intersection during all peak hours.

In order to accommodate the additional traffic at the Blakely road/Williams Road intersection, a southbound left turn lane on Blakely Road and a westbound left turn lane on Williams Road is assumed in the analysis. These additional turn lanes provide sufficient capacity to maintain acceptable levels of service through 2037.

The Blakely Road at US 2/7 and Severance Road intersection operates at unacceptable levels of service for the 2037 weekday evening peak hour.

7.1.7 Bayside Intersection Evaluation Matrix

An evaluation matrix for these alternatives can be found in Figure 18.

Alt. 1

No Build Alternative

Alt. 2A

Operational Modifications @

Blakely & Lakeshore

Alt. 2B

Operational & Geometric Modifications @

Blakely & Lakeshore

Alt. 3

Roundabout @ Blakely &

Lakeshore

Alt. 4A

Dead End E Lakeshore and New

Connector Road

Alt. 4B

Dead End E Lakeshore with No

Connector Road

Engineering Design+ $0 $10,000 $50,000 $280,000 $340,000 $80,000

Roadway / Signal Construction $0 $65,000 $120,000 $2,500,000 $1,900,000 $280,000

Stormwater Improvements (Meets Standards) $0 $0 $300,000 $300,000 $500,000 $500,000

Stormwater Improvements (Exceeds Standards) $0 $0 $700,000 $700,000 $1,100,000 $1,000,000

Resident (Construction) Engineering $0 $5,000 $10,000 $230,000 $200,000 $70,000

Total (Meets Standards, Not Including ROW) $0 $80,000 $480,000 $3,310,000 $2,940,000 $930,000

Total (Exceeds Standards, Not Including ROW) $0 $80,000 $880,000 $3,710,000 $3,540,000 $1,430,000

Alignment / Traffic Signal Changes -New pedestrian signals, video

detection, and controller

Convert Blakely Road left turn lane to

left/through lane; Addition of 250'

northbound travel lane; Changes to existing

signal at Blakely & Lakeshore Drive

Single lane roundabout at

E/W Lakeshore Drive

Dead end E Lakeshore Drive; Construct

new road segment; Signalize Laker

Lane intersection

Dead end E Lakeshore Drive; Construct

left turn lanes on NB Blakely Road and

WB Williams Road

Traffic - 2037 PM Peak Levels of Service

Blakely Road & Lakeshore Drive

Overall LOS F LOS C LOS C LOS B LOS A LOS A

Blakely Rd NB through LOS F LOS D LOS C LOS B LOS A LOS A

W Lakeshore Dr SB left LOS D LOS E LOS E LOS A No left turn No left turn

Blakely Road & Laker Lane

Laker Lane left/right LOS F LOS F LOS F LOS F Signalized: LOS B LOS F

Blakely Road & Williams Road

Williams Road left/right LOS D LOS D LOS D LOS D Additional lanes: LOS D LOS D

Blakely Road & US 2/7 & Severance Road

Overall LOS D LOS D LOS D LOS D LOS D LOS E

Traffic - 2037 PM Peak Volume to Capacity Ratio

Blakely Road & E/W Lakeshore Drive

Overall 0.97 0.95 0.78 0.91 0.81 0.81

Blakely Rd WB through 1.30 0.94 0.73 0.85 0.78 0.78

W Lakeshore Dr EB left 0.81 0.86 0.88 0.71 No left turn No left turn

Blakely Road & Laker Lane

Laker Lane left/right (AM peak) 1.27 1.27 1.27 1.27 0.86 1.27

Blakely Road & Williams Road

Williams Road left/right 0.44 0.44 0.44 0.44 0.44 0.46

Bicycle Safety - No change No change

Slight Improvement

(High visibility crossing at major

approach)

Slight Improvement

(Possible facilities on new connector road)

Slight Improvement

(Eliminate approach from intersection)

Pedestrian Safety -

Decreased

(Flashing Don't Walk Phase is

concurrent with moving vehicles)

Decreased

(Flashing Don't Walk Phase is concurrent with

moving vehicles)

Slight Improvement

(High visibility crossing at major

approach)

Improved

(Removal of intersection approach at E

Lakeshore Dr, proposed 5' sidewalk on new

connector road)

Improved

(Fewer intersection approaches, Expanded

Bayside park and trails)

Vehicle Safety - No change No change

Improved

(Fewer conflict points, slower

vehicle speeds)

Improved

(Fewer intersection approaches)

Improved

(Fewer intersection approaches)

Utility Impacts - No impacts No impacts Yes Yes Yes

ROW Impacts - No impacts Minimal Yes (Town-Owned) Yes Yes (Town-Owned)

Agricultural Lands - No Potential Potential Yes Yes

Archaeological - No No No No No

Historic - No No No No No

Hazardous Materials - No No No No No

Floodplains - No No No No No

Fish & Wildlife - No No No No No

Rare, Threatened & Endangered Species - No No No Potential Potential

Public Lands - Sect. 4(f) - No Potential Potential No No

LWCP - Sect. 6(f) - No Potential Potential No No

Managed Lands No No No No No

Noise - No No No No No

Wetlands - No No No No No

New Impervious Surfaces - No Yes - 20% New Yes - 16% New Yes - 33% New No - 5% Less Impervious

Stormwater Accommodations None

Minimal

(No new areas to use for

stormwater infiltration)

Minimal

(No new areas to use for stormwater infiltration)

Moderate

(Center and splitter islands can

be used for stormwater

treatment)

High

(Opportunities for treatment along new

connector road on sandy soils)

High

(Removed impervious area and oportunities

for treatment in expanded park)

Aesthetics - No Change No Change Improved Improved Improved

Community Character - No Change No Change Improved Slight Improvement Decrease (Cut-thru Traffic)

Economic Impacts - No Change No Change Slight Improvement Slight Improvement Slight Improvement

Conformance to Reg. Transp. Plan - Yes Yes Yes Yes Yes

Satisfies Purpose & Need No Yes Yes Yes Yes Yes

Act 250 - No No No No No

Section 404 - Wetlands (USACOE) - No No No No No

Section 401 Water Quality Certification - No No No No No

State Wetlands Permit - No No No No No

Stream Alteration Permit - No No No No No

Construction Phase Storm Water Discharge Permit

(General Permit 3-9020)- No No Yes Yes Yes

Operational Phase Storm Water Discharge Permit

(General Permit 3-9015)- No No Yes Yes No

Lakes & Ponds - No No No No No

Rare, Threatened, and Endangered Species - No No No No No

Section 1111 Permit - No No No No No + - Engineering Design costs include those costs associated engineering and design for both intersection and stormwater (Meets Standards) improvements 3-Oct-17

Perm

its

Co

sts

En

gin

eeri

ng

Imp

acts

Lo

cal

&

Reg

ion

al

Evaluation Matrix: Lakeshore Drive / Blakely Road Intersection Improvements

Malletts Bay Transportation Scoping Study Project




Bicycle and Pedestrian Improvement Alternatives

7.2.1 West Lakeshore Drive Alternative I – No Build

In the case of the No Build alternative for West Lakeshore Drive, no improvements would be made to accommodate bicyclists and pedestrians along the corridor. The current roadway and sidewalk alignments would remain the same.

7.2.2 West Lakeshore Drive Alternative II – Shared Travel Lanes

The first build alternative for bicycle and pedestrian accommodations is to restripe and sign West Lakeshore Drive with shared-lane markings (i.e. “sharrows”) to create more visibility for cyclists on the roadway. In this alternative, the roadway alignment and sidewalk would remain as it currently exists.

The use of warning signs and shared lane markings, or “sharrows”, can increase visibility of bicyclists on the roadway and make road users generally more aware that they are in a recreational area. Improved signage and pavement markings was one of the recommendations of the 2015 AARP study and can encourage both safer cycling and driving.

An example cross-section of this alternative is shown in Figure 19.

Figure 19: Shared Travel Lanes Cross Section

Do Sharrows Work?

An FHWA study in Chapel Hill, NC found that, after the placement of shared lane markings (a.k.a “sharrows”), fewer people rode on the sidewalk and bicyclists were usually given more operating space on the roadway.



7.2.3 West Lakeshore Drive Alternative III – On Road Bike Lanes

Alternative III includes five-foot wide bike lanes along the roadway. Much of the existing sidewalk would be retained except for one location where it needs to be relocated slightly.

This alternative proposes an expanded curb line (32 feet) to accommodate two 11-foot travel lanes and two five-foot bike lanes. In order to accommodate the new bikes lanes, a small portion of the sidewalk must be reconstructed. This length of sidewalk stretches 325 feet east from the Malletts Bay Campground entrance. Excluding this section, the existing sidewalk will be retained. It is recommended that all existing crosswalks be kept in their current location and restriped if needed.

Conceptual plans for this alternative are shown in the Appendix. An example cross-section is shown in Figure 20.

Figure 20: On Road Bike Lanes Cross Section

7.2.4 West Lakeshore Drive Alternative IV – Southern Shared Use Path

The third alternative involves the construction of a 10-foot wide shared use path with a seven-foot vegetated buffer for stormwater treatment along the southern side of West Lakeshore Drive. This shared use path would replace the current sidewalk.

Due to the high traffic volumes along West Lakeshore Drive, most inexperienced cyclists either choose to ride on the sidewalk or not ride at all through this area. Shared use paths are a great alternative to on road bike lanes as they are more accessible for less experienced cyclists and offer fewer pedestrian conflicts than riding on the sidewalk.



The shared use path generally follows the alignment of the current sidewalk and would be 10-feet wide except for two pinch point locations. The first pinch point is at a large oak tree in front of the house located at 419 West Lakeshore Drive. The second location is just west of Shore Acres Drive at a row of very dense hedges. At these two locations, the path would narrow to five-feet wide and return to 10-feet immediately after the obstruction.

With the seven-foot green strip and ten-foot path, there are numerous right-of way (ROW) conflicts along the corridor. Potential private property impacts to note are as follows:

Moorings Marina southern boat lot and fence

Retaining wall at Jakes Place

Numerous property owner easements required

Malletts Bay Cemetery

In order to avoid the fence line of the Malletts Bay cemetery near the intersection with Prim Road, a realignment of West Lakeshore Drive is required. The proposed alignment shifts the centerline northerly by approximately ten feet, with a 250-foot taper back into the existing alignment. The realignment ties into the proposed realignment of the West Lakeshore Drive and Prim Road intersection roughly 120 feet before the center of the intersection. The taper returns to the existing alignment at Coates Island.

Conceptual plans for this alternative are provided in the Appendix. An example cross section is shown in Figure 21.

Figure 21: Shared Use Path Cross Section



7.2.5 West Lakeshore Drive Alternative IV (A) – Shared Use Path with Waterfront Access

A potential addition to the fourth alternative is the construction of a 10-foot wide shared use path which gives waterfront access and a scenic outlook just to the north of Moorings Marina. Access to this path is provided by crosswalks connecting to the southern shared use path. This section of path is proposed to be approximately 980-feet long, stretching from Moorings Marina to the International Sailing School.

West Lakeshore Drive is the recreational center of Colchester and this alternative provides access to a lesser used beach and could potentially attract new visitors, as well as provide accommodations for more people than Bayside Beach alone. Given the proximity to the Malletts Bay Boat Club and Moorings Marina, this side path may become a popular spot and can be expanded to include benches and other landscaping features.

Conceptual plans for this alternative are provided in the Appendix.

7.2.6 West Lakeshore Drive Alternative IV (B) – Shared Use Path with Scenic Overlook

Another potential addition to the selected alternative is the construction of a 10-foot wide shared use path, north of Moorings Marina, which has an overlook at the elevation of the roadway. This path will provide waterfront access using three staircases which lead directly to the beach. This scenic path can be accessed using any of the three crosswalks which connect to the path on the southern side of the roadway.

The overlook is proposed to be approximately 700-feet long and would require the construction of a retaining wall and two additional sets of stairs with railings which lead to the beach. The overlook is connected to the shared use path on the southern side of the road by one existing crosswalk and two new crossings. As with Alternative IV (A), this path could include benches and landscaping to encourage visitors to stop and enjoy the Bay.

Conceptual plans for this alternative are provided in the Appendix.

7.2.7 West Lakeshore Drive Alternative IV (C) – Northern Sidewalk Extension

This alternative includes the construction of a five-foot sidewalk along the northern side of West Lakeshore Drive for the westernmost third of the project area. The sidewalk is proposed to extend from the Harbor View Plaza Shopping Center to the Public Boat Launch. This sidewalk provides a connection from the boat launch to the retail needs and amenities such as restaurants, a general store, and a hardware store. It is recommended that the existing curb cuts for the Plaza be narrowed to increase safety for both vehicles and sidewalk users.



Conceptual plans for this alternative are provided in the Appendix. A graphic for this alternative is shown in Figure 22.

Figure 22: Alternative IV (C) – Northern Sidewalk Extension

7.2.8 West Lakeshore Drive Alternatives Evaluation Matrix

An evaluation matrix for the alternatives presented for bicycle and pedestrian improvements along West Lakeshore Drive can be found in Figure 23.



Figure 23: West Lakeshore Drive Alternatives Evaluation Matrix

Alt. 1No Build

Alt. 2Shared Use Lanes

Alt. 3Bike Lanes

(both sides of road)

Alt. 4Shared Use Path

(south side of road)

Alt. 4AAlt. 4 + Section at Water

Elevation

Alt. 4BAlt. 4 + Overlook Area

Alt. 4CAlt. 4 + North sidewalk at

western endEngineering Design+ $0 $10,000 $80,000 $220,000 $250,000 $290,000 $250,000Roadway/Path Construction $0 $20,000 $510,000 $1,300,000 $1,550,000 $1,420,000 $1,600,000Stormwater Improvements (Meets Standards) $0 $0 $900,000 $900,000 $900,000 $900,000 $900,000Stormwater Improvements (Exceeds Standards) $0 $0 $2,400,000 $2,400,000 $2,400,000 $2,400,000 $2,400,000Retaining Wall, Railing & Stairs Construction $0 $0 $0 $0 $50,000 $1,780,000 $0Resident (Construction) Engineering $0 $0 $40,000 $130,000 $160,000 $130,000 $160,000Water line Relocation Cost $0 $0 $0 $2,500,000 $2,500,000 $2,500,000 $2,500,000

Total (Meets Standards, Not including ROW) $0 $30,000 $1,530,000 $5,050,000 $5,410,000 $7,020,000 $5,410,000

Total (Exceeds Standards, Not including ROW) $0 $30,000 $3,030,000 $6,550,000 $6,910,000 $8,520,000 $6,910,000

Typical Section11' travel lanes

1-3' paved shoulder5' sidewalk

11' travel lanes 1-3' paved shoulder

5' sidewalk

11' travel lanes5' bike lanes

11' travel lanes1-3' paved shoulders

10' paved shared use path







Bicycle Access - Shared use lanes 5' bike lanes Adds shared use path Adds shared use path Adds shared use path Adds shared use path

Pedestrian Safety - No Change No Change

Improved for Path Users (Bicyclists and pedestrians are

given more room and separated from vehicles)







Vehicle Safety - No ChangeSlight Improvement

Bikes are given a facility separate from vehicle lanes

ImprovedBikes are on a separated facility

off of the roadway


off of the roadway


off of the roadway


off of the roadway

ROW Impacts - No No Moderate High Moderate ModerateAgricultural Lands - No Potential Potential Potential Potential PotentialArchaeological - No No No No No NoHistoric - No No No No No NoHazardous Materials - No No No No No NoFloodplains - No No No Yes Potential NoShoreland - No No No Yes Potential NoFish & Wildlife - No No No No No NoRare, Threatened & Endangered Species - No No No Potential Potential NoPublic Lands - Sect. 4(f) - Yes Yes Yes Yes Yes YesLWCP - Sect. 6(f) - No No No No No NoManaged Lands - No No No No No NoNoise - No No No No No NoWetlands - No No Yes Yes Yes YesNew Impervious Surfaces - No Yes - 13% New Yes - 17% New Yes - 21% New Yes - 24% New Yes 24% New

Stormwater Accommodations NoneModerate

(Narrow green belt for bioswales)

Low(Narrowed greenbelt does not

accommodate bioswales)

Moderate(Narrow green belt for bioswales)




Aesthetics - No impacts Minimal Improved Improved w/ Water Views Improved w/ Water Views ImprovedCommunity Character - No impacts Minimal Improved Improved Improved ImprovedEconomic Impacts - No impacts Minimal Positive Positive Positive PositiveConformance to Reg. Transp. Plan - Potential Yes Yes Yes Yes YesCompliance With Current Zoning - Yes Yes Yes No* No* YesSatisfies Purpose & Need No No Partial Yes Yes Yes YesAct 250 - No No Potential Potential Potential PotentialSection 404 - Wetlands (USACOE) - No No Yes Yes Yes YesSection 401 Water Quality Certification - No No Yes Yes Yes YesState Wetlands Permit - No Yes Yes Yes Yes YesStream Alteration Permit - No No No No No NoConstruction Phase Storm Water Discharge Permit (General Permit 3-9020)

- No Yes Yes Yes Yes Yes

Operational Phase Storm Water Discharge Permit (General Permit 3-9015)

- No Yes Yes Yes Yes Yes

Lakes & Ponds - No No No Potential Potential NoRare, Threatened, and Endangered Species - No No No No No NoSection 1111 Permit - No No No No No No

+ - Engineering Design costs include those costs associated with engineering and design for bike/ped, water line and stormwater (Meets Standards) improvements 3-Oct-17 * - Not compliant with current zoning as written. May be approved after Town review

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Stormwater Management Alternatives Two packages of stormwater management recommendations were developed to address identified needs throughout the project area.

Recommendations by sub-basin for each of the five watershed areas within the project area (Malletts Bay-West Lakeshore Drive, Malletts Bay-East Lakeshore Drive, Crooked Hollow Creek, Smith Creek, and the Moorings Stream) are included in the Appendix. A summary of the stormwater recommendations, metrics, and costs by watershed area is included in Table 15. A map of the sub-basins is included as Figure 5, and specific recommendations for each sub-basin can also be reviewed in the web map produced for this project at the following URL: http://arcg.is/0fTWrX.

7.3.1 Stormwater Management System Alternative: Meeting Standards

The “meets standards” recommendations address existing basic roadway drainage issues along East and West Lakeshore Drive, provide water quality treatment along these corridors to current state standards where reasonable, and coordinate with other planned infrastructure projects in this corridor. The “meets standards” package also identifies key stormwater management improvements in upland Town roadway drainage systems that ultimately contribute runoff to Inner Malletts Bay within the project area.

“Meets Standards” improvements specifically address basic roadway drainage problems, address deficiencies related to MRGP standards (where identified), and meet the Vermont Stormwater Management Manual’s (VSMM) stormwater treatment standards for public transportation “Redevelopment-Major Maintenance” projects. The VSMM “Redevelopment-Major Maintenance” standard applies to jurisdictional stormwater projects on roadways where no net new impervious surface is being constructed (so, for instance, full-depth reconstruction within the existing road alignment and footprint). It requires that designers address existing drainage issues and implement practices for water quality treatment where practicable, but meeting the standard does not require treating 100% of the WQv. For public closed drainage infrastructure on Town parcels (SC-03, SC-11), the relevant standard from the VSMM is Section 2.4 Redevelopment, so the Water Quality Treatment Standard applies (at 50% of the WQv, 25% impervious cover reduction, or an equivalent combination of treatment and impervious cover removal).

Sizing assumptions for treatment practices to meet state standards in the Malletts Bay – West Lakeshore Drive watershed included that the proposed treatment practices would usually be bioswales designed to the requirements and guidelines of the 2017 Vermont Stormwater Management Manual. Where the soils are not suitable for infiltration practices, linear gravel wetlands were proposed to provide water quality treatment in the green space between the proposed recreational path and the roadway. In the Malletts Bay - East Lakeshore Drive watershed, surface bioswales were applied where there appeared to be adequate space adjacent to the



roadway – primarily at the north and south ends of East Lakeshore Drive. Where existing development was located very close to the roadway, such that surface bioswales were not feasible, subsurface linear infiltration practices were proposed instead. Although it may be possible to site these “invisible green infrastructure” practices with a lower level of impact on existing uses of the right-of-way compared to surface bioswale features, curbing recommendations and the disturbance required to install these practices still represent substantial impacts to existing uses of the right-of-way.

In the upland Crooked Hollow Creek, Smith Creek, and Moorings Stream watersheds, curb-cut surface bioretention areas were preferentially applied where curb-and-gutter closed drainage systems already existed and there appeared to be adequate space adjacent to the roadway. Where existing roadway drainage systems consisted of open swales, surface bioswales were proposed where soils appeared to be suitable for infiltration practices. Linear or end-of-pipe gravel wetlands were proposed in areas where the soils were mapped as less suitable for infiltration (primarily the Moorings Stream watershed).

7.3.2 Stormwater Management System Alternative: Exceeding Standards

The “exceeds standards” package of stormwater management recommendations addresses the same basic issues as the “meets standards” package, but where practicable, these recommendations maximize the capture and treatment of runoff to and from existing Town highway stormwater systems. For instance, for treatment practices that exceed standards on West Lakeshore Drive, in addition to the surface bioswales proposed to meet standards, the northern half of the roadway would be collected via offline, deep sump catch basins and piped across the road, to be connected to the perforated drain line in the bioswale or linear gravel wetland. Additional bioswale or gravel wetland length, or overall area for bioretention, is generally required in each drainage area to provide treatment for the larger capture volumes.

7.3.3 Stormwater Management System Alternatives Summary

Figure 24 and Table 15 summarize, by alternative, how much of the Town roadway drainage system area within the area draining to Malletts Bay along East and West Lakeshore Drives can be “greened” – or treated to an extent that fully meets or exceeds the standards and criteria identified in Section 6.1. Approximately 70% of the total area draining to Town roadway drainage systems can be “greened”, Along East and West Lakeshore Drives, site and right-of-way constraints often limit the siting of water quality treatment practices. In the upland areas of the Crooked Hollow Creek, Smith Creek, and Moorings Stream watersheds, many of the Town roadway drainage systems are located in subdivisions where roadways were constructed to historic or current Town of Colchester Public Works Specifications



and Standards, and thus there is often adequate area in the right-of-way for siting of water quality treatment practices as retrofits.

The recommendations for all 49 sub-basins within the project area (Appendix H) include a set of improvements that “meet” standards. Many, but not all, of the sub-basins also have a set of recommendations that “exceed” standards. At Colchester High School (SC-03), for example, improvements are already planned that exceed standards, such that further recommendations are not necessary. In other cases, such as the upper watershed area of the Moorings Stream (SC-09) and along portions of East and West Lakeshore Drive, site constraints prevent the development of improvements beyond what is necessary to meet standards.

Starting in 2018, the Town of Colchester will be required, as an MS4, to revisit these recommendations as the Public Works staff begin to develop a Phosphorus Control Plan on a Town-wide basis, the end product of which will be a package of improvements that meets the developed lands phosphorus reduction target that DEC is now developing. The specific wasteload allocation target number that the Town will receive is not yet known, but it will represent a 20.5% reduction from the 2001-2010 base load expressed in the Lake Champlain Phosphorus. The recommendations provided here, for the drainage systems serving Town roadway infrastructure, currently represent an estimated 36% reduction in annual phosphorus loading for the “meets standards” scenario, and a 55% reduction for the “exceeds standards” scenario (Table 15 and Figure 24). As the Town chooses a preferred alternative, and as staff begin to implement improvements identified in this scoping study, there is great opportunity to optimize- whether by choosing practices for early implementation that capture and treat existing untreated Town roadway system drainages, or by otherwise selecting projects with the greatest environmental cost-benefit.

The environmental cost-benefit of implementing all recommendations, whether for meeting or exceeding standards, varies substantially between the five watersheds across the project area (Table 15 and Figure 26), as well as between individual sub-basins (Appendix H). Assuming all recommendations for either the Meets Standards or Exceeds Standards were implemented, costs on a per-pound P load reduction basis are lower in the upland Crooked Hollow Creek, Smith Creek, and Moorings Stream watersheds as compared to in the watersheds that drain directly to Malletts Bay along East and West Lakeshore Drives (Figure 26).



Figure 24: Summary of “Greened” Acres Possible for Town Roadway Drainage Areas



Figure 25: Summary of Maximum Percent Reduction in Annual Total Phosphorus Load by Watershed and Alternative

14 17

5357

52

3634

50

71

66

5355

0

10

20

30

40

50

60

70

80

Malletts Bay ‐ WestLakeshore Drive

Malletts Bay ‐ EastLakeshore Drive

Crooked HollowCreek

Smith Creek Moorings Stream All RoadwayDrainage SystemContributing Areas

Percent Red

uction in Annual Total P Load

Town Roadway Drainage Areas ‐ Meets Standards

Town Roadway Drainage Areas ‐ Exceeds Standards

Lake Champlain P TMDL Target ‐ Malletts Bay Lake Segment ‐ 20.5%



Figure 26: Summary of Implementation Costs per Pound of Annual Total Phosphorus Load Reduction by Watershed and Alternative

7.3.4 Stormwater Management System Recommendation Details, Metrics, and Costs

Key characteristics from the sub-basin delineations and infrastructure assessments (Table 3), as well as implementation costs and environmental benefits associated with each set of recommendations for identified Town roadway drainage systems within the project area, are summarized in Table 15. A full explanation of the recommendations in each sib-basin can be found in Appendix H. The narrative recommendations in the tables are organized by sub-basin ID and road name within each watershed area. Narrative recommendations are followed by a summary of characteristics and metrics, as well as implementation cost estimates and cost-benefit of which is briefly described below.

Drainage area characteristics and metrics:

• Primary Hydrologic Soil Group (HSG), as derived from the Chittenden County Soil Survey for the sub-basin area

$1,128,000

$1,721,000

$948,000

$1,887,000

$675,000

$3,070,000

$2,441,000

$1,993,000

$4,753,000

$1,340,000

$0

$500,000

$1,000,000

$1,500,000

$2,000,000

$2,500,000

$3,000,000

$3,500,000

$4,000,000

$4,500,000

$5,000,000

Malletts Bay ‐ WestLakeshore Drive

Malletts Bay ‐ EastLakeshore Drive

Crooked HollowCreek

Smith Creek Moorings Stream

Implemen

tation Cost per Pound og Annual Total P Red

uction

Town Roadway Drainage Areas ‐ Meets Standards Town Roadway Drainage Areas ‐ Exceeds Standards



• Total drainage area (acres), only for areas contributing to the Town roadway drainage systems

• Estimated Water Quality Volume (WQv) (acre-feet), based on the 2017 VSMM Water Quality Treatment Standard’s required runoff capture and treatment depth of 1 inch18 and the pervious and impervious areas contributing to the Town roadway drainage systems

• Breakdown of impervious and pervious surfaces treated by proposed improvements within the sub-basin

• Runoff storage volume captured by proposed improvements

• Estimated total phosphorus base load (lbs/year) for the WQv, accounting for reductions already achieved by existing stormwater BMPs, if any (see Section 3.4 for calculation details).

• Estimated total phosphorus load to be removed by proposed improvements on an annual basis (lbs/year), calculated based on the estimated total phosphorus base load, annual runoff volume anticipated to be captured by proposed BMPs, and percent pollutant removal efficiencies for the proposed BMP types as included in the Lake Champlain BMP Scenario Tool19 (see Table 13)

Table 13: BMP Type and P Removal Efficiency

BMP Type BMP P Removal Efficiency (%) Bioretention 76 Extended Dry Detention Pond 12 Gravel Swale 21 Gravel Wetland 61 Infiltration Chamber 98 Infiltration Trench 98 Porous Pavement (Asphalt) 75 Sand Filter 60 Surface Infiltration 98 Wet Pond / Created Wetland 52

• Percentage of the sub-basin Water Quality Volume treated by proposed improvements

18 2017 Vermont Stormwater Management Manual Rule and Design Guidance, effective July 1, 2017. Available at

http://dec.vermont.gov/sites/dec/files/wsm/stormwater/docs/Permitinformation/2017%20VSMM_Rule_and_Design_Guidance_04172017.pdf

19 2015 Lake Champlain BMP Scenario Tool Requirements and Design. Technical report prepared by Tetra Tech for U.S. EPA Region 1, April 2015. Available at https://www.epa.gov/sites/production/files/2015-09/documents/lake-champlain-bmp-scenario-tool-report.pdf



• A “yes/no” evaluation of whether major erosion or gullying exists down-stream of the sub-basin outfall. In these cases, additional phosphorus removal beyond what is specified for implementation of water quality BMPs is anticipated if the down-stream erosion issues are addressed in coordination with BMP retrofits.

• A “yes/no” evaluation of whether the roadways within the sub-basin were built to older Town standards (e.g., 30-foot wide roads in low-traffic residential subdivisions), such that a "road diet" may be feasible if substantial reconstruction of the roadway is needed in future. The current Town standard is 26 ft. width; low traffic volume roads (less than 50 homes or 500 daily trips) may potentially be as narrow as 22 feet. Further evaluation of the concept of road diets will be required to determine specific guidance on how much to reduce width. Recommendations will need to be consistent with the roadway cross sections of Chapter 14 (22’ roadways are only acceptable for roadways serving less than 100VPD), and will need to account for projects with wider (24’+) roadways that were approved with the understanding that on-street parking would be used to meet zoning requirements for parking spaces.

Implementation Cost Estimates for Curbing, Stabilization, and Drainage Upgrades

• Gully stabilization costs were provided as estimated lump sum costs based on localized erosion area dimensions (length, area, and height) with estimates for key payables including erosion prevention/sediment control & mobilization, clearing, fill, bed or toe armor, outfall repair, restoration and seeding, and engineering design/construction oversight.

Implementation Cost Estimation for Stormwater Treatment Practices / BMPs

• Costs for implementing proposed stormwater BMPs were estimated using the cost function employed in Vermont’s Best Management Practice Decision Support System (BMPDSS)20, as well as current installation cost estimates per cubic foot of BMP storage volume provided in 2016 guidance from U.S. EPA Region 121. The costs are calculated based on the following equation:

total cost = installation cost (I) + land cost (L) + fixed cost (F)

Where:

20 Technical memo: BMP Cost Function in Vermont’s BMPDSS, from Tham Saravanapavan of Tetra Tech to Jennifer Callahan of Vermont DEC, dated October 30, 2007.



I = BMP installation cost per cubic foot (CF) of storage volume in 2016 dollars, updated to account for inflation to the year 2017, using a 2.5% inflation rate, specific to the practice type as shown in Table 14.

Table 14: BMP Type and Unit Construction Cost

BMP Type BMP Unit Construction Cost

(2017 $ / CF) Bioretention $15.85 Extended Dry Detention Pond $6.97 Gravel Wetland $9.00 Infiltration Chamber $69.55 Infiltration Trench $12.81 Sand Filter $18.39 Surface Infiltration $6.40 Wet Pond / Created Wetland $6.97

L = $0 as easement or land purchase costs for individual BMPs are not known at this stage

F = project-specific estimate of design/permitting costs, estimated at 20% of installation costs.

Total Implementation Cost Estimate (sum of the curbing/stabilization/drainage upgrade costs and the BMP implementation costs)

Total Implementation Cost per Pound of Phosphorus Load Removed



Table 15: Sub-Basin Recommendation Summary

Sub-basin Area (ac)

Sub-basin WQv (CF)

Impervious Area Treated

(ac)

Pervious Area Treated

(ac)

Proposed Storage

Volume (CF)

Curbing, Stabilization, and

Drainage Upgrade Cost

Estimate (2017 $)

BMP Cost Estimate (2017 $)

Total Implementation

Cost Estimate (2017$)

Implementation Cost Per Pound P

Load Removed (2017 $)

Est. annual avg runoff

volume (CF)

Estimated Total Base P Load,

Including Existing BMPs (lbs/year)

Estimated P Load

Removed by New BMPs

(lbs./yr)

% Sub-basin WQv Treated by New BMPs

% Reduction in Total P Load

Malletts Bay - West Lakeshore Dr. Area 57.6 70,020 5 26 18,120 $158,000 1,923,600 50 7 26 14

Malletts Bay - East Lakeshore Dr. Area 163.2 115,270 8 30 19,435 $1,164,000 $291,000 $1,455,000 $124,000 3,978,000 84 14 17 17

Crooked Hollow Creek 78.7 87,310 22 56 44,550 $100,000 $848,000 $948,000 $39,000 2,893,200 46 25 51 53

Smith Creek 183.8 207,790 51 125 72,340 $679,000 $1,208,000 $1,887,000 $51,000 6,887,100 67 38 35 57

Moorings Stream 77.9 53,710 11 67 45,520 $179,000 $496,000 $675,000 $34,000 1,780,100 39 20 85 52

TOTAL 561 534,100 98 305 199,965 $2,122,000 $2,843,000 $4,965,000 $48,000 17,462,000 285 104 37 36

Malletts Bay - West Lakeshore Dr. Area 57.6 70,020 7 28 40,745 $182,000 1,923,600 50 17 58 34

Malletts Bay - East Lakeshore Dr. Area 163.2 115,270 17 73 62,460 $1,139,000 $924,000 $2,063,000 $58,000 3,978,000 84 42 54 50

Crooked Hollow Creek 78.7 87,310 22 56 105,060 $100,000 $1,893,000 $1,993,000 $62,000 2,893,200 46 33 120 71

Smith Creek 183.8 207,790 51 125 205,660 $679,000 $4,074,000 $4,753,000 $109,000 6,887,100 67 44 99 66

Moorings Stream 77.9 53,710 11 67 107,190 $179,000 $1,161,000 $1,340,000 $65,000 1,780,100 39 21 200 53

TOTAL 561 534,100 108 350 521,115 $2,097,000 $8,052,000 $10,149,000 $65,000 17,462,000 285 156 98 55

Stormwater Alternatives Metrics and Implementation Costs

Mee

ting

Stan

dard

sEx

ceed

ing

Stan

dard

s

All implementation costs included in transportation alternatives

All implementation costs included in transportation alternatives

Watershed Name



7.3.5 Alternatives Evaluation Criteria and Scoring

The detailed recommendations in Appendix H include observations recorded about each sub-basin, and the proposed recommendations, which were used to develop a “score” for each sub-basin relative to the following criteria:

Existing roadway drainage concerns – score was assigned based on the type(s) of problems present, with 1 point added for each of the following concerns presented by the roadway drainage system’s current condition. Although sites are generally anticipated to receive between 1 and 3 points, the maximum score a site can receive is 5.

Ponding, inadequate number/spacing of catch basins, or existing road grade too flat

Surface runoff directed into street, or private properties impacted by uncontrolled run-on from roadways

Existing roadway drainage system has critical slope or capacity limitations

Lack of curbline flow and/or runoff directed over steep embankment

Existing system and/or outfall in fair to poor overall condition

Existing stormwater volume, sediment, and nutrient concerns – score was assigned based on the type(s) of problems present, with points added for each of the following concerns presented by the overall drainage area’s current condition. Although sites are generally anticipated to receive between 1 and 6 points, the maximum score a site can receive is 12.

Roadway runoff receives does not receive water quality treatment prior to discharge to tributary streams or Malletts Bay (4 points), or roadway runoff receives insufficient water quality treatment (2 points)

Uncontrolled or insufficiently controlled roadway runoff volume results in major erosion or gullying, or sedimentation at culvert outlets or outfalls (4 points); or results in minor erosion, gullying, or sedimentation (2 points)

Uncontrolled or insufficiently controlled roadway runoff volume contributes to downstream stream channel and stream bank instability, with additional transport of sediment and nutrients to Malletts Bay (4 points)

Environmental priority – relative environmental impact on nearest receiving water (e.g., proximity, location) and how “active” any existing water quality, erosion, or sedimentation issues were during field observations made in the course of this and prior projects, with 1 being the smallest impact and 5 being the greatest impact.

Extent to which Recommendations Address All Existing Concerns – up to 3 points were allowed for the extent to which recommendations addressed existing roadway drainage issues; an additional 3 were allowed for the extent the recommendations addressed stormwater volume/sediment/nutrient concerns



Integration with Other Infrastructure Improvements – up to 3 points were allowed depending on the extent the recommendations could be coordinated or integrated with other planned infrastructure improvements, with 1 point for either West Lakeshore Drive bike-ped improvements or Blakely Rd./Lakeshore Drive intersection improvements, 1 point for Malletts Bay Sewer coordination, and 1 point for potential coordination with water line or other upcoming infrastructure improvements

Potential Utility Conflicts – Under this criterion, all sub-basins began with a base score of 4, and 1 point was subtracted for each anticipated utility conflict. Utility conflicts considered included water, sewer, natural gas, and electric. Along West Lakeshore Drive, for stormwater improvements that include bioswales in coordination with the separated recreational path (Alternative 4), water line relocation will likely be required. The cost of this specific improvement is likely to be one that Colchester Fire District No. 2 cannot reasonably fund. The anticipated cost of that relocation is included in the project cost estimate for that transportation alternative, but not in the stormwater recommendations tables XX-1 and XX-2.

Right-of-Way and Adjacent Property Impacts – relative amount of impact on existing uses of the Town highway right-of-way, as well as the anticipated level of need to acquire new right-of-way to implement recommendations for this drainage system area. A score of 2 points indicates a package of recommendations that does not require acquiring new ROW and poses no impact to existing uses of ROW areas; 1 point indicates a minor impact or reduction of existing use of ROW, but generally no requirement for new ROW; and 0 points indicates a substantial impact on existing ROW uses or a need to acquire additional ROW to implement recommendations.

Overall Constructability – relative ease with which recommendations could be implemented, including whether the recommended practice(s) could be constructed on publicly-owned land or with a willing landowner-partner, existing access to portions of the drainage area in need of improvement, and the amount of additional assessment and engineering design work that would be required to move the recommendations to implementation. The maximum score an area can receive is 3, indicating a suite of recommendations that should move quickly and easily to implementation.

Ease of operation – including the amount and frequency of maintenance likely to be required and whether maintenance activities will be straightforward to complete. The maximum score a set of recommendations can receive is 3, indicating a project with infrequent maintenance needs that are easily completed.

The type of ownership involved in each set of recommendations, and the amount of additional engineering that will be needed for implementation, are also presented in the matrix. These measures are not included in the score tabulated for each potential project, but are qualitatively scored as follows:



Project Type “key”:

A Private property

B State property or right-of-way

C Public property (town-owned land or right-of-way)

D Hybrid; part public land, part private land

Need for Additional Engineering “key”:

L Project requires some amount of engineering design to ensure proper sizing

M Project requires full engineering

H Project requires full engineering and substantial coordination with other major improvement projects



8 Selection of Preferred Alternatives A preferred alternative for each of the scoping studies was selected based on the evaluation matrices, public input, and the desires of the Town. The preferred alternatives were presented to the Colchester Selectboard on October 10, 2017 and were approved for further development in the Town’s future planning efforts. A description of these alternatives and associated costs are summarized in this chapter.



Bayside Intersection Preferred Alternative The preferred alternative for the Bayside intersection is a single-lane modern roundabout in place of the existing intersection with short term signal operational improvements to improve intersection efficiency. In the short term, it is proposed to optimize signal timings at the existing signal and install a protected left-turn phase from Blakely road into Bayside Park.

The long-term recommendation at this intersection is a roundabout. The proposed roundabout will be a single lane roundabout with a 130-foot inscribed diameter (curb-to-curb) with a mountable apron and landscaped center island. The roundabout is expected to operate with an overall Level of Service A with a volume to capacity ratio of 0.85 during the 2037 weekday evening peak hour. Queues on Blakely Road are expected to decrease by nearly 1,000 feet with the roundabout in place as compared to the No Build scenario.

All intersection approaches will have a splitter island between the entry and exit lanes which acts as a pedestrian refuge to improve safety at the crosswalks by creating a two-phase crossing. The major pedestrian crossing approach, West Lakeshore Drive, is proposed to have a highly visible crosswalk including Rectangular Rapid Flashing Beacons (RRFB) to heighten driver awareness of crosswalk users on this leg of the roundabout.

The roundabout will align with the proposed shared use path and provides cyclists with the option of entering the road and taking the lane or staying on the sidewalk and dismounting their bicycle to use a crosswalk.

The proposed roundabout is estimated to cost $3,310,000 which includes the cost to improve stormwater to meet State standards.

A graphic of the preferred intersection and stormwater improvements is shown in Figure 27.


91 Selection of Preferred Alternative

Figure 27: Bayside Intersection Preferred Alternative



West Lakeshore Drive Preferred Alternative The preferred alternative which was brought forward to the Selectboard is the construction of a ten-foot shared use path on the southern side of West Lakeshore Drive with a five-foot sidewalk on the north side of the road extending from the Harbor View Plaza to the Public Boat Launch. This alternative will align with both the redesigned intersection of West Lakeshore Drive and Prim Road as well as the proposed alternative at the Bayside intersection.

The major elements of this alternative include the construction of the shared use path, integration of stormwater improvements which will meet or exceed statewide standards, a relocation of West Lakeshore Drive in the vicinity of Prim Road, and the relocation of the water line which currently runs under the south side of West Lakeshore Drive. It is assumed that these elements will be constructed simultaneously in order to minimize impacts and lane closures on West Lakeshore Drive. The proposed sidewalk at the western end of the project corridor could be vulnerable to vehicle conflicts with the current driveway arrangement at the Harbor View Plaza. It is recommended that the plaza driveways be narrowed and made more visible so that pedestrians will be protected by a vegetated buffer as much as possible. Along with these access management improvements, it is also recommended to replace the multiple crosswalks in the vicinity of the plaza with a single crosswalk, strategically located, to improve vehicle and pedestrian safety.

This alternative has a total estimated cost of $5,410,00 which includes the 10-foot shared use path, the northern sidewalk, stormwater improvements, and the relocation of the waterline. The breakdown of estimated cost is as follows:

Shared Use Path and Road Relocation - $1,650,000

Northern Sidewalk - $360,000

Meeting Stormwater Standards – $900,000

Waterline Relocations - $2,500,000

A graphic of the proposed West Lakeshore Drive improvements can be found in Figure 28.



Figure 28: West Lakeshore Drive Preferred Alternative



Stormwater Preferred Alternative The preferred alternative for the stormwater scoping study is to construct stormwater best management practices (BMPs) and drainage improvements that will result in Meeting Standards for the Moorings Stream, Crooked Creek, and Smith Hollow Creek watersheds; to construct BMPs and drainage improvements that will result in Exceeding Standards for the Malletts Bay - East Lakeshore Drive watershed; and for staff to continue exploration to identify other specific sub-basin improvements where Exceeding Standards may be financially beneficial to future permit compliance related to phosphorus reduction in Lake Champlain. The primary driver behind Exceeding Standards in the Malletts Bay – East Lakeshore Drive watershed is the cost per pound of phosphorus removal. The East Lakeshore Drive watershed was the only one identified as having a lower cost per pound of phosphorus removal from improvements designed to Exceed Standards than the cost per pound under the Meets Standards improvements. The stormwater improvements identified in the Malletts Bay - West Lakeshore Drive watershed were included in the selection of bicycle and pedestrian enhancement and intersection enhancement alternatives. The conceptual construction cost estimate for the preferred alternative is $5.6 million; a breakdown of the estimated implementation costs by watershed is shown in Figure 29.

Figure 29: Stormwater Preferred Alternatives Implementation Costs

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