The redevelopment of a portion of the Village of Tannersville in the early 2000's by the Hunter Foundation prompted this stormwater retrofit project to improve runoff conveyance and treatment in a 1.2 acre area of high-density commercial buildings and parking facilities. Prior to the implementation of this project, stormwater and associated pollutants flowed directly into Sawkill Creek. The parking area is not only located very close to the creek, but slopes towards it as well. New techniques have been developed to retrofit these situations and are demonstrated in this project. In order to mitigate the associated negative water quality impacts, this project employs permeable pavement, rain gardens, an underground conveyance system, and a total suspended solids (TSS) separator to intercept and treat stormwater runoff.
Project Goals and Objectives
The primary project goal is to protect Sawkill Creek by retaining and treating stormwater runoff from the parking area and buildings. The secondary project goals are to demonstrate "low impact development" (LID) stormwater management techniques, as well as to improve the aesthetics and ease of use of the parking area by eliminating puddles and mud during rain events.
How Do Impervious Surfaces Affect Our Streams and Water Quality?
Impervious surfaces such as asphalt, cement, and roofing prevent infiltration of rainfall into the soil. This limits groundwater recharge while promoting rapid runoff into the closest stream, pond, or wetland. Runoff collects and carries pollutants such as road salts, oil and gasoline, fertilizers, chemicals, and pathogens into waterbodies. Rapid runoff from major storms can erode stream banks and beds, which results in degraded water quality and potential property and infrastructure damage. Aquatic ecosystems are also degraded as a result.
Stormwater Mitigation and Water Quality Improvement Measures
This project utilizes several best management practices to mitigate and treat stormwater runoff and protect water quality.
Underground Stormwater Conveyance System and Total Suspended Solids Separator
A runoff conveyance system was designed and installed for the site to capture and treat stormwater from various catchments. This system includes catch basins, manholes, and underground piping. Two catch basins capture runoff from Route 23A and the paved enterance leading to the parking area. This captured stormwater is then directed to a total suspended solids (TSS) separator which separates the suspended solids, oil, grease, and floatables prior to outletting the stormwater to the Sawkill Creek.
This project utilizes a permeable pavement system consisting of gravel within a cellular containment structure (geoweb). Unlike traditional pavement, the permeable pavement allows rainwater to move vertically down through the parking surface and into the underlying soils.
Rain gardens are depressions in the ground that consist of loose, deep soils that encourage rainfall infiltration and are typically planted with native vegetation. This project employs 2 rain gardens to reduce runoff quantity and velocity by encouraging goundwater infiltration.
Riparian Buffer Plantings
A riparian buffer is a vegetated area (a "buffer strip") near a river or stream that protects the body of water from the negative impacts of adjacent land uses while providing many other habitat and water quality benefits. This project site was planted with native riparian vegetation to help slow stormwater runoff and flood waters, protect the streambank from erosion, and enhance wildlife habitat.
Click here for a complete Hunter Foundation Stormwater Retrofit Project report
Click here to view more information on GCSWCD's stream and floodplain restoration projects throughout the Schoharie basin