Whether a town is reviewing a proposal to construct a small subdivision or constructing its own stormwater project, a necessary first step is determining the size and type of the Green Stormwater Infrastructure technique that suits the situation best. Check out these links below...


Vermont Green Stormwater Infrastructure Simplified
Sizing Tool for Small Projects

Stone Environmental working in partnership with the Vermont League of Cities and Towns to create this useful Vermont-based tool. The tool is spreadsheet based. For more information on this Green Stormwater Infrastructure Tool click here.

VLCT Documents
GSI Simplified Sizing Tool for Small Projects Fact Sheets [November 2015] (PDF)
GSI Simplified Sizing Spreadsheet [November 2015] (Excel Document)
MAC Model LID/GSI Stormwater Management Bylaw [October 2015] (Word Document)

All of the components of the GSI Toolkit can be accessed online here.

To view the November 2015 webinar to see how to use the tool, click here to watch the video.
Note: The recording started several minutes early, the presentations start at 4min 45 sec. Also, you will need to register (Name/Email) to view the recording. This Word document provides answers to questions posed during the webinar.


Other Useful Calculators and Tools to Explore

U.S. Environmental Protection Agency (EPA) National Stormwater Calculator
The EPA has released their National Stormwater Calculator, a desktop application that estimates the annual amount of rainwater and frequency of runoff from a specific site anywhere in the United States (including Puerto Rico). Estimates are based on local soil conditions, land cover, and historic rainfall records.

It is designed to be used by anyone interested in reducing runoff from a property, including:

The Calculator accesses several national databases that provide soil, topography, rainfall, and evaporation information for the chosen site. The user supplies information about the site’s land cover and selects the types of low impact development (LID) controls they would like to use.


Center for Neighborhood Technology Green Values Stormwater Calculator
The National Green Values Calculator is a tool for comparing the performance, costs, and benefits of Green Infrastructure, or Low Impact Development (LID), to conventional stormwater practices. While the calculator is based upon the hydrology of the Great Lakes region, this calculator is highly refined and can be used to get a general sense of how green infrastructure might work in other areas.

Runoff Reduction Calculator
Developed by the Center for Watershed Protection (CWP) and the Chesapeake Stormwater Network (CSN) The Runoff Reduction Method is an innovative system for stormwater design that focuses on Best Management Practices’ (BMPs’) capacity to reduce overall runoff volume as well as remove pollutants. The method also incorporates built-in incentives for Low Impact Development, such as preserving forests and reducing soil disturbance and impervious cover. The CWP and CSN have also been working with the Virginia Department of Conservation and Recreation (DCR) to integrate the Runoff Reduction method into proposed stormwater regulations and an updated stormwater management handbook, and have developed Excel-based calculators for estimating runoff reduction for new development and redevelopment .