Lifecycle Assessment Analysis of Engineered Stormwater Control Methods Common to Urban Watersheds

Best management practice (BMP) selection typically focuses on economic costs and management criteria. Generally, there is very little consideration of lifecycle assessment (LCA)-determined environmental impacts (LCA impacts) associated with management practice implementation and operation, although the inclusion of LCA considerations are becoming increasingly common within state governments and industries as part of sustainability initiatives. LCA modeling provides an evaluation of the environmental impacts of a product or process in a cradle to grave scenario following ISO 140440 protocol. LCA can provide value in preliminary decision making for construction of sustainable stormwater management structures. To assist in that effort, the LCA impacts of typical upper Midwest U.S. urban stormwater management scenarios were evaluated. Primary, traditional structures (porous detention, sand filtration basins) were considered both as stand-alone systems and as systems coupled with green BMPs (rain gardens, vegetated swales, porous pavement). Designs were based on a Rapid City, South Dakota U.S. drainage basin configuration and national stormwater design manuals. Both midpoint and endpoint LCA impacts were determined based on a 30-year design life. The functional unit used was the volume of stormwater treated by the system for a design storm of 51 mm of rain in 24 h. LCA modeling results demonstrated that although implementation of green stormwater BMP offsets did effectively reduce LCA impacts compared with traditional management strategies, there was little difference between each of the green BMPs implemented. Transportation of management practice infrastructure was the greatest LCA-impact contributor, whereas the use of locally-sourced materials provided significant benefits to the impact categories examined.