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Green Stormwater Infrastructure Completed in Hinesburg
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New Green Stormwater Infrastructure Completed in Hinesburg Lewis Creek Association, December 2014 At the beginning of October, the Lewis Creek Association completed the construction of a stormwater treatment project known as the Silver Street Rain Garden. The project represents a continuation of the work completed as part of a Townwide hydrology study completed in 2011 and 2012, which targeted the Silver Street site as a potential location for a stormwater treatment system. The project site is located at the intersection of VT Route 116 and Silver Street in the Town of Hinesburg, was initiated and managed by the Lewis Creek Association with funding provided by Vermont’s Department of Environmental Conservation Ecosystem Restoration Program. The stormwater treatment system was designed to fit within the sloping site along Silver Street between an existing drainage swale and the Hinesburg Masonic Lodge Building on Townowned land. The site was selected because it is the location of three storm drainage outfalls that drain a portion of the Village. Prior to constructing the rain garden, runoff from the three outfalls was conveyed directly to the Laplatte River by an existing swale and culvert system with little treatment. The rain garden will treat stormwater runoff from a 6.7acre subwatershed collected by the existing storm drainage systems, with approximately 2.6 acres or 39% of the contributing watershed consists of impervious surfaces. The primary design objective is to capture the runoff from a 1inch rainfall event, which generally represents 90 percent of the rainfall events occurring annually. Treatment goals are to remove 80% of the average annual total suspended solids (TSS) and to remove 40% of the total phosphorus (TP) load present in the contributing stormwater runoff. The stormwater treatment system was designed in a twotiered configuration. The upper treatment cell collects all of the stormwater from the existing drainage outfalls, transfers stormwater to the lower treatment cell using a perforated riser structure, and bypasses larger storms to the swale along Silver Street. The roadside swale was reshaped, revegetated, and stone check dams were installed as part of the overall project. The lower treatment cell was Figure 0: Completed Upper Treatment Cell
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12/31/2014 Silver Street Blog Post.
Transcript of Green Stormwater Infrastructure Completed in Hinesburg
New Green Stormwater Infrastructure Completed in Hinesburg
-‐-‐ Lewis Creek Association, December 2014
At the beginning of October, the Lewis Creek Association completed the construction of a stormwater treatment project known as the Silver Street Rain Garden. The project represents a continuation of the work completed as part of a Town-‐wide hydrology study completed in 2011 and 2012, which targeted the Silver Street site as a potential location for a stormwater treatment system. The project site is located at the intersection of VT Route 116 and Silver Street in the Town of Hinesburg, was initiated and managed by the Lewis Creek Association with funding provided by Vermont’s Department of Environmental Conservation Ecosystem Restoration Program.
The stormwater treatment system was designed to fit within the sloping site along Silver Street between an existing drainage swale and the Hinesburg Masonic Lodge Building on Town-‐owned land. The site was selected because it is the location of three storm drainage outfalls that drain
a portion of the Village. Prior to constructing the rain garden, runoff from the three outfalls was conveyed directly to the Laplatte River by an existing swale and culvert system with little treatment.
The rain garden will treat stormwater runoff from a 6.7-‐acre subwatershed collected by the existing storm drainage systems, with approximately 2.6 acres or 39% of the contributing watershed consists of impervious surfaces.
The primary design objective is to capture the runoff from a 1-‐inch rainfall event, which generally represents 90 percent of the rainfall events occurring annually. Treatment goals are to remove 80% of the average annual total suspended solids (TSS) and to remove 40% of the total phosphorus (TP) load present in the contributing stormwater runoff.
The stormwater treatment system was designed in a two-‐tiered configuration. The upper treatment cell collects all of the stormwater from the existing drainage outfalls, transfers stormwater to the lower treatment cell using a perforated riser structure, and bypasses larger storms to the swale along Silver Street. The roadside swale was reshaped, re-‐vegetated, and stone check dams were installed as part of the overall project. The lower treatment cell was
Figure 0: Completed Upper Treatment Cell
designed as a bio-‐retention basin allowing stormwater to pond a maximum of 18 inches before discharging through a stone outlet weir. A bio-‐retention configuration provides the greatest opportunity for stormwater to infiltrate, evaporate, or be utilized by the plants.
The Hinesburg Highway Department working together with Distinctive Landscaping of Charlotte constructed the two-‐celled treatment system, including stone filter berms, outlet piping and overflow weirs, and planted over 1,200 native wetland plants and wildflowers in addition to 150 shrubs to help slow and treat stormwater draining towards the LaPlatte River. Final design and construction oversight services were provided by Milone & MacBroom of Waterbury.
Beyond improving local water quality, the stormwater treatment system will enhance local aesthetics, require minimal maintenance, and serve as a public demonstration of simple measures that can be used to treat stormwater within a built environment.
Figure 0: Completed Lower Treatment Cell
