Evaluation of stormwater BMP alternatives in the Malden River Watershed

Abstract

Stormwater runoff degrades urban streams through a variety of hydrologic and water quality changes. Green infrastructure is one alternative to traditional methods of stormwater management. This report evaluates the feasibility of four green infrastructure Best Management Practices (BMPs) in the Malden River watershed. The WERF BMP SELECT model was used to generate performance and cost data for bioretention systems, swales, permeable pavement, and constructed wetlands in a portion of the Malden River watershed. Due to space constraints, bioretention systems and swales were found to have limited applicability within the streets of the study site. Permeable pavement was 5 to 70 times more expensive than the other BMP alternatives. Wetlands were found to be the most cost-effective alternative. A 5.3 acre wetland would cost $3.9 million and provide 50% Total Phosphorus reduction, 57% Total Suspended Solids reduction, and 33% flow reduction. However, limited land availability constrains the development of a wetland within the study site.