Green Infrastructure and Low Impact Design can improve water quality, beautify the urban landscape, and provide habitat for wildlife. But what locations are a priority for installation of these best management practices (BMPs)? And what types of BMPs are appropriate for a specific site?
Ben Fairbank, Janice Schmidt, and Alex Krofta answer these questions in their Conway School project entitled A Neighborhood Strategy for Improving the Lower Mill Pond Watershed. This report was prepared for Easthampton Massachusetts. The project team worked with Jim Gracia, Easthampton DPW; Jessica Allan, City Planner; and Matt Reardon of MassDEP.
The focus of the report is Lower Mill Pond in Easthampton, a long-abused and often-overlooked relic of the industrial age. Though point-source pollution from the nearby factories is a thing of the past, the current threat to water quality is an aging storm sewer system that discharges directly to the pond and its tributary streams.
To prioritize areas for treatment, we divided the subwatershed into storm sewer catchment areas and then employed a GIS tool provided by the MassDEP to calculate the amount of Directly Connected Impervious Area in each. Next we identified Environmental Justice areas within the subwatershed, and areas lacking open space or parks, as priorities for green infrastructure BMPs.
To determine where certain BMPs may be appropriate, we used NRCS soils data to estimate infiltration capacity based on soil type and depth to groundwater. Then we searched the assessor’s database for vacant land, city-owned land, or federally-owned land since planners may have better access to these sites than to private properties in this densely-built residential neighborhood.
Based on this analysis, we developed a framework for stormwater planning in the subwatershed, and a site-scale design process. We imagined green infrastructure BMPs for site types and soil conditions typical to the Lower Mill Pond neighborhood, and also suggested programmatic and gray infrastructure solutions where appropriate.
(Above article by Alex Krofta, Conway School)