The Town of Littleton's Clean Lakes Committee obtained a Clean Water Act Section 319 grant from the Massachusetts Department of Conservation and Recreation (DCR) to implement a series of low impact development (LID) projects and other improvements to the area in and around the Long Pond beach to better treat stormwater, eliminate or minimize beach closings, and generally improve the pond's water quality. The 99-acre pond is listed by the State as "impaired" by nutrients, low dissolved oxygen, and noxious aquatic plants. Excessive nutrient loading comes from the adjacent residential septic tank systems and runoff from the curb-and-gutter stormwater collection system within this rapidly urbanizing community northwest of Boston. Littleton's long-term goal for Long Pond is water quality improvement that will return the beach area to an attractive recreation destination for town residents.
Geosyntec's Scope of Services
Working hand-in-hand with the Clean Lakes Committee, Geosyntec designed an innovative watershed-based approach to manage stormwater inputs to Long Pond. A highlight of Geosyntec's design is a 1.5-acre engineered wetland treatment area that was designed to capture and treat the stormwater flows from 50 acres of developed residential upland that had previously flowed directly into the pond. Over 90% of the annual stormwater volume from the upland now flows through this constructed wetland resulting in a significant reduction in sediment and nutrient loading to the pond.
In addition, Geosyntec developed and implemented in-lake management measures including selective herbicide treatment for aquatic vegetation control, and shoreline dredging and access improvements to the immediate beach area, making it a more inviting place to bring families.
Based on the success of the Section 319 grant-funded projects, Geosyntec assisted the Town in applying for and obtaining a separate $300,000 lake and pond demonstration grant from the DCR to expand the initial LID program. With the additional funding, Geosyntec designed and deployed several additional LID techniques (bioswales; bioretention cells; rain gardens; rain barrels; porous paving stones; lawn care education; water conservation; and septic system inspection, maintenance, and repair) at selected locations throughout the watershed, all of which are designed to slow down the rate of stormwater runoff, allowing it to infiltrate into the ground rather than be funneled directly into the pond via culverts and pipes.
One project of significant note in this phase of work was the replacement of a stormwater outfall pipe next to the town beach with a vegetated bioswale containing a series of wooden check-dams. This outfall was a significant point source for nutrients, sediments, and bacteria to the pond. The bioswale slows down and captures the runoff, allowing it to infiltrate into the ground before it reaches the pond.
Due to the replacement of the old outfall pipe and the construction of the engineered wetland area and other individual LID projects near the town beach and throughout the immediate area, water quality at the Long Pond town beach has improved to the point where, during the summer of 2006, there were no beach closures due to poor water quality. Geosyntec's comprehensive stormwater improvement program directly benefited the community by making the area around the town beach aesthetically pleasing, improving accessibility, and making it more family-friendly.