Rockwell Pond Management Plan, Non-Point Source Pollution Evaluation, Bioretention Conceptual Design, and Grant Support
Weston & Sampson conducted and prepared the Rockwell Pond Management Plan, which provided information about the watershed, in-pond water monitoring, tributary and outlet monitoring, groundwater monitoring, sediment analyses, and ecological assessments. The results of the sampling and analysis demonstrated that sedimentation from land uses had caused “shallowing” of the pond and phosphorus and fecal coliform loading had impaired the pond’s ecosystem and recreational opportunities.
The Plan recommended better stormwater management control of sediment, phosphorus, and other non-point source pollutants. This study estimated that 2,227 pounds per year of phosphorus and 9,906 pounds per year of nitrogen flowed into Rockwell Pond. Pollutants were quickly transported to the North Nashua River.
Analysis of the Rockwell drainage area identified locations for specific Best Management Practices (BMPs) to reduce sources of sediment, nitrogen, and phosphorus. Although installation of structural BMPSs would be completed by the Leominster Department of Public Works, additional s. 319 assistance was necessary for source reduction measures recommended by the Massachusetts Department of Environmental Protection (MassDEP) Clean Water Toolkit, including rain gardens, bioretention areas, and grass swales.
Weston & Sampson prepared conceptual designs for five demonstration raingardens and eight edge-of-road bioretention facilities for use in a s. 319 Grant Application. The conceptual “retrofit” design modified the existing stormwater infrastructure to provide substantial nutrient and pollutant reduction, while encouraging infiltration and maintaining a system to control run-off from high rainfall storms. These Low Impact Development (LID) BMPs are estimated to reduce phosphorus loading by 18 pounds per year, reduce total suspended solids (TSS) by 36,700 pounds per year, and reduce wet weather bacteria counts while increasing groundwater recharge.