Square Pond Watershed Improvement Project, Phase II

Attachment A: Candidate Site List for Road and Beach BMP’s

Road sites – Two road sites have been identified as high impact (Elm St. and Cedar Dr.) based on the degree of erosion from documentation in the May 2006 Square Pond Survey. Two additional sites (Dogwood Dr. and Stone Post Rd.) were listed as medium impacts but have significantly deteriorated following rain events of 2009 and 2010. Costs listed are preliminary estimates. Detailed estimates will be provided for Grant Administrator approval prior to project initiation. Sites will be subject to change pending satisfactory completion of CSAs cost-share agreements and permitting. Pollutant load calculations follow EPA Region 5 Load Estimation Model or WEPP Federal Road Model.
  1. Dogwood Drive (Town of Shapleigh) – Town Road, Shapleigh. This road site includes moderate surface, ditch and road shoulder erosion. Significant runoff flows to Dahlia Street and pools over 3 separate septic systems within close proximity to Square Pond. Recommendations include regrading the road (300’), adding surface material, ditching (150’) and installing detention basin. Construction Cost: $5,000 ($2,500 grant, $2,500 match)

Pollutant Load Calculation (per year) 1.04 tons sediment, 0.88 lbs of phosphorus

  1. Cedar Drive (near 286 Cedar Drive) – Private Road, Shapleigh. This site has severe surface erosion, moderate road and shoulder erosion, bare soils and shoreline erosion. Recommendations include regrading surface (100’), establishing ditching (100’) and install turnouts, install a rain garden and add vegetated buffer. Construction Cost: $5,000 ($3,000 grant, $2,000 match)

Pollutant Load Calculation (per year) 1.8 tons sediment, 1.53 lbs of phosphorus

  1. Willow St/West Shore Dr– Town Road, Acton. Severe ditch erosion, bare banks, moderate surface erosion, clogged culvert. Recommendations include reestablishing ditching, erosion control mix on bank, increase detention basin area, and reinstall culvert with armored inlet and outlet.

Construction Cost: $4,000 ($2,000 grant, $2,000 match)

Pollutant Load Calculation (per year) 1.4 tons sediment, 1.19 lbs of phosphorus

  1. Elm Street – Private Road, Shapleigh. This site has severe surface, ditch and road shoulder erosion. Recommendations include installing catch basin, stabilizing bare soil with erosion control mulch and vegetating banks. Construction Cost: $8,500 ($5,000 grant, $3,500 match)

Pollutant Load Calculation (per year) 2.4 tons sediment, 2.04 lbs of phosphorus

  1. Stone Post Road – Town Road, Shapleigh. This town road was identified as a medium impact site in the survey. There is moderate erosion the steep section that drains down to Indian Village Road, which runs parallel to the lake. Runoff from the road causes excess stormwater runoff on Indian Village Road as well as the residential properties below. Recommendations include ditching (200’), new surface material and grading on the road, installing a turnout into a settling basin just above Indian Village Road and possibly a diverter across the road (since it is not usually plowed by the town). Construction Cost: $3,300 ($2,000 grant, $1,300 match)

Pollutant Load Calculation (per year) 2.1 tons sediment, 1.79 lbs of phosphorus

  1. Treasure Island – TILOA. Treasure Island is a gated community accessed only by ferry. Transportation of bulk aggregate, erosion control mix and vegetation is feasible by barge which has limited carrying capacity. Remediation projects are limited to hand-carried quantities which make large scale, and even small and medium scale projects, difficult to implement. Working with a local contractor who resides on the island, utilize small tractor and trailer to transport erosion control mulch (50 yards total) in 4 yard increments to be stockpiled on the Island for projects. YCSWCD staff and TILOA Board members will track quantities and projects completed which will be listed in NPS site reports and included in FPR. Material and Delivery Cost: $1,800 ($1,100 grant, $700 match)

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