Citation:

Impact/Purpose:

To develop a spreadsheet-based optimization tool for municipal stormwater managers and their consultants who are interested in identifying a suite of BMPs that provide the most effective stormwater/nutrient treatment for the least cost on a watershed basis.

Description:

During 2014, EPA Region 1 contracted with Tetra Tech, Inc. to work with a regional technical Advisory Committee to develop an Excel-based stormwater/nutrient BMP optimization tool (Opti-Tool) using regional precipitation data and regionally calibrated BMP performance data from UNH Stormwater Center for total phosphorus (TP), total suspended solids (TSS), and Zinc. In 2015, BMP performance curves for nitrogen (TN) will be included, as well. The list of structural BMPs includes LID and GI practices: biofiltration, dry pond, grass swale, gravel wetland, infiltration basin, infiltration trench, porous pavement, and biofiltration with internal storage reservoir (ISR for nitrogen removal). The Opti-Tool consists of a Microsoft-Excel platform and external SUSTAIN BMP process and optimization modules. The user interacts with the Excel platform for data input, and can direct Excel to call the SUSTAIN module to estimate BMP performance and provide optimization at a given assessment point in the watershed. Input categories include data on subwatershed area, connectivity; conduit/stream length, shape; BMP type, location, unit cost; optimization assessment point, decision variables, objective. In the post-processing step, the tool will automatically retrieve the optimization results and generate tradeoff curves between total BMP costs and the designated stormwater control targets (either pollutant load-based, or cost-based). Cost-effective BMP sizing strategies for meeting control targets will be processed and presented to the user in the form of depth of runoff to be treated in individual subwatersheds. Detailed information of analyzed scenarios will also be included in the output folder, allowing for advanced users to look into possible alternatives to the near-optimal solutions. The Opti-Tool tool will provide the ability to evaluate options for the best mix of structural and non-structural BMPs in a particular geographic area, and is scheduled to be ready for testing at the community level by the end of 2014. Further work in 2015 involves development of nitrogen removal curves using existing regional BMP data; technical enhancements in model construction to assure user-friendly access for planning level as well as more complex design purposes; development of a companion tracking & accounting and reporting tool suitable for R1 NPDES stormwater permitting.

Record Details: