Hamden, CT
Town of Hamden’s Bioretention Project
The Town of Hamden’s Bioretention Project is the largest municipally owned rain garden in the state! Save the Sound, in partnership with the Town of Hamden, completed this large-scale rain garden project at Hamden Town Center Park to improve local water quality, restore habitat, and enhance community resilience. The project transformed approximately 2.5 acres of lawn into a functioning green infrastructure system that now manages runoff from an 88-acre urban watershed draining Dixwell Avenue and surrounding neighborhoods. Prior to the project, stormwater often overflowed directly into Pardee Brook and the Mill River, carrying pollutants and inundating the park.
The newly constructed rain garden was engineered with layers of soil, sand, and rock, and planted with more than 7,000 native grasses, flowers, and shrubs thanks to additional support from the Land Trust of Hamden. These plantings naturally filter pollutants such as fertilizers, road salt, and chemicals. Community volunteers helped complete the planting, strengthening local stewardship in the Town of Hamden.
Town Center Park Bioretention System. Credit: Save the Sound, Mill River Watershed Association, and Town of Hamden.
Town Center Park during installation of the Bioretention System. Credit: Save the Sound.
Town Center Park before installation of the Bioretention System. Credit: Save the Sound, Mill River Watershed Association, and Town of Hamden.
Town Center Park before, during, and after installation of the Bioretention System. Credit: Save the Sound, Mill River Watershed Association, and Town of Hamden.
Town Center Park before, during, and after installation of the Bioretention System. Credit: Save the Sound, Mill River Watershed Association, and Town of Hamden.
After rain garden installation. January 10, 2024. Credit: Chris Bresky.
Impact Information:
A 40,000 sq ft rain garden was installed and included restoration of an acre of park land. The system now treats over 20 million gallons of stormwater annually, reducing flooding and restoring more natural hydrology to Shepard Brook and the Mill River. Beyond its environmental benefits, the project created valuable wildlife habitat and a welcoming green space for residents to enjoy. Adaptive management, more planting, and stewardship is planned for 2025 and 2026.
Period of Completion:
2020-2023
Total Cost:
$723,00 ($18/sq ft)
Funding Sources:
Construction
$255,000 grant from CT DEEP Section 319 (Clean Water Act) to Save the Sound. Used for materials, outreach, project management, and sign design and procurement.
$435,000 of in-kind services from the Town of Hamden's Departments of Engineering and Public Works. This included (1) engineering designs and specifications, (2) local permits, (3) construction – excavation, grading, final site work, and sign installation, (4) mulch and compost, and (5) unanticipated costs for removing knotweed contaminated soil and replacement with clean topsoil.
$30,000 grant to Hamden Land Conservation Trust (HLCT) from the Claire C. Benett Watershed Fund. Used to purchase additional plants, support outreach events sponsored by HLCT, plants installed in 2024, and mugwort cutting.
For Post Construction Adaptive Management, knotweed control, and final planting of the 1st basin in 2026:
$80,000 Congressional Direct Spending Award from Sen. Blumenthal
~$96,000 from Congresswoman DeLauro (part of a larger award to promote and expand green infrastructure in the Watersheds of New Haven Harbor)
Flooding
Land Use
Nature-based Solutions
Stormwater Management
Water Quality
Green Infrastructure
