The Center for Neighborhood Technology (CNT) developed an easy-to-use online calculator that determines the impact that “green interventions” have on overall lot and site discharge, detention basin sizing, and average annual discharge. The calculator looks at the following 6 green interventions:
- Roof Drains to Raingardens at All Downspouts
- Half of Lawn Replaced by Garden with Native Landscaping
- Porous Pavement used on Driveway, Sidewalk and other non-street pavement
- Green Roofs
- Provide Tree Cover for an Additional 25% of Lot
- Use Drainage Swales instead of Stormwater Pipes
Once the appropriate green interventions have been selected, a set of site characteristics are input by the user. The calculator allows for site scenario parameters (new suburban development to existing single-family home). From there, input focuses on site characteristics like lot, street size, number trees, roof size, and soil type.
In addition to the site discharge comparison, the calculator provides a cost comparison between conventional and green stormwater design. You can add the calculator to your tool kit at the CNT’s green values website.
