Design and Size your Green Infrastructure Best Management Practices

In this section, we provide tools to help you design your site with Green Infrastructure BMPs.  These tools also help you determine the correct size for the BMPs you have selected to adequately manage stormwater on site.

Design and placement of Green Infrastructure BMPs should be informed by the natural and built environment both on-and off-site, as well as client/stakeholder preferences for cost and long-term operations & maintenance considerations. Design is usually an iterative process when used to optimize water quality protection, stream bank erosion reduction, appropriate flow conveyance, and flood storm mitigation.

Tools to design and size Green Infrastructure BMPs:

What Storm Type is Your Site In?:  To accurately design and size your site, you first need to determine what Storm Type your site is in.  You will select the storm type Green Infrastructure Implementation Form that matches the storm type your site resides in.

Green Infrastructure Implementation Forms and Tutorial:  The Green Infrastructure Implementation Form calculates the number and size of BMPs selected by the user to manage stormwater on site to the specifications of the local stormwater requirements.  The Green Infrastructure Implementation Form Tutorial provides a comprehensive step-by-step instruction and examples for completing the form.

Precipitation Maps: Precipitation maps are used by engineers and other hydrology modelers to assess the size of a particular frequency storm for the project location. Engineers model their site’s rainfall response to different size storms that are expressed in inches over a 24-hour period (e.g. "Design Storm").  To accurately size many BMPs, you will need to know the 24 hour rainfall depth for your jurisdiction or area.

Infiltration Rate of Soil:  To accurately size Green Infrastructure BMPs, each site must be tested for its soil infiltration rate.  This factsheet lists easy step-by-step instructions to complete the infiltration testing.

Choosing the Right Garden:  This tool helps users select the type of rain garden configuration that best matches the site characteristics and constraints.   This tool is complimentary to the Green Infrastructure Implementation Form and can be used prior or after completing that form.