Restoring Water Quality in the Willow Brook Watershed Through LID Retrofits

students posing with construction equipment
Thursday, November 3, 2011

By Robert Roseen1, PhD, PE, D.WRE, James Houle1, CPSWQ, Robert Dowling1, Melodie Esterberg2, Director, Lorie Chase3, Sally Soule4

1UNH Stormwater Center, 2Rochester Department of Public Works, Cocheco River Watershed Coalition3, NHDES Grant Manager4

Willow Brook is a tributary to the Cocheco River in the urban center of Rochester, NH. This small urban stream is impaired for Primary and Secondary Contact Recreation (e. coli). Its direct receiving waters, the Cocheco River, are impaired for Aquatic Life Use (benthic macroinvertebrates and habitat) as well as Primary Contact Recreation (e.coli). Likely sources are nonpoint source pollutants from urban stormwater runoff. The Cocheco River Watershed Coalition (CRWC) in cooperation with the City of Rochester Public Works Dept.(DPW), and the UNH Stormwater Center (UNHSC) developed and implemented a plan for installation of LID practices, conducted outreach and educational activities, effectively reduced the impervious cover percentages to address water quality impairments in the watershed. The project was funded through NHDES 319 Watershed Assistance Grants to addresses the nonpoint source pollution from urban runoff in two pilot locations.

The first demonstration location was a small K-4 neighborhood school with no stormwater management that directly impacted the usability of the surrounding areas. The project resulted in the implementation of eight different LID retrofit strategies virtually eliminating most of the direct runoff from the sites impervious areas. These strategies included raingardens (3), a dry well, rainbarrels, roof drains, pervious concrete sidewalks, and a porous asphalt basketball court by a donation from Pike Industries. The second demonstration location was a recently built residential subdivision with conventional curb, catch basin and gutter stormwater conveyance. Retrofits included a rain garden and two tree filters to effectively disconnect roughly 78 percent of the impervious cover. Educational programming for the neighborhood residents and students was also included in the project. This presentation will cover general successes and lessons learned over the project period to date.