SUSTAIN

SUSTAIN simulates pollutant load removal for most BMPs through the use of pollutant-specific first order decay rates from SWMM4 User’s Manual (James, W. et al., 2002). Pollutant removal efficiencies of wetlands are drawn from Treatment Wetlands (Kadlec and Knight, 1996). Street cleaning pollutant removal efficiency is specified by the user.

The user is required to load files of varying formats. This includes: GIS shape files for land use, soil, roads, streams, and groundwater depth, raster files for elevation and U.S. Geological Survey Multi-Resolution Land Characteristic (USGS MRLC) land use, and time series data for climate/inflow time. The user may enter values to override default coefficients and exponents for soil detachment, wash-off, etc. for pervious surfaces, as well as the build-up and wash-off rates of solids on impervious surfaces. The user selects BMPs from a prepopulated library and enters the characteristics (i.e. size, weir type, filter media, etc.)

The model calculates outflow, pollutant concentration, and pollutant load in the form of a time series in tabular, graphic, or csv format.

• Tool may be used during the planning phase and implementation phase of stormwater program
• The model does not allow the user to develop point source loads
• Model factors in groundwater, evapotranspiration, and snowmelt, but does not factor in in-stream transport
• BMPs are either modeled as either an infiltration structure or a detention structure
• The tool is no longer being developed or supported by the EPA
• The user may input coefficients, decay rates, etc. to either override default values or develop a condition/pollutant not represented in the model by default
• With considerable user input, users may simulate other BMPs outside of the default BMPs, such as reduced or disconnected imperviousness
• Sediment is classified into three types: sand, silt, and clay
• This tool is free and available to the public, however it requires ArcGIS 9.3 w/ Spatial Analyst extension and Microsoft Excel

• The model has a BMP optimization tool to determine best placement and selection of BMPs for optimal cost-effectiveness
• The model allows different options for the method used to estimate many of its components
• This tool may be used to support Reasonable Assurance Analysis (RAA)