Calculation and Report Preparation Tools

Stormwater Management Facilities Report

All development and redevelopment projects with BMPs are required to provide a Stormwater Management Facilities Report (SMFR). An outline of items that the SMFR should address is available on this page.

Calculation Spreadsheets

MSD developed the Maximum Extent Practicable (MEP) tool, sometimes referred to as the “MEP Spreadsheets.” Instructions on how to use the MEP Spreadsheets are provided here. (Spreadsheets were updated on October 19, 2016.)

The volume of runoff that is not discharged can be credited toward the project’s channel and flood detention storage requirement. MSD recognizes curve number (CN) modification to establish this credit, and a CN modification tool is also available.

RECARGA

Wisconsin DNR and the University of Wisconsin-Madison developed RECARGA, a rain garden and bioretention modeling tool that MSD frequently uses. Data files are available for use in developing annual runoff reduction estimates using continuous simulation modeling:

Representative area hourly rainfall and evapotranspiration rates for native plants — Missouri native plants
Representative area hourly rainfall and evapotranspiration rates for turf grass — Turf grass

SWMM v.5

EPA’s SWMM (version 5.1) can be used to model a variety of BMPs, including bioretention, pervious pavement, and rainwater harvesting.

National Stormwater Calculator

EPA’s National Stormwater Calculator can be used to estimate a site’s annual pre-development runoff (volume) using continuous simulation modeling. It may also be used to size BMPs whose effectiveness is based on retention, including downspout disconnection, rainwater harvesting, and green roofs.