Runoff Reduction Method

Runoff Reduction Method technical memo, spreadsheets and background documents: The Runoff Reduction Method was developed by the Center for Watershed Protection (CWP), the Chesapeake Stormwater Network (CSN), and the Virginia Department of Conservation and Recreation and is described in the technical memo referenced below. The memo outlines an innovative system for stormwater design. While the memo provides extensive background research on BMP performance, the method focuses on determining BMPs' capacity to reduce the overall volume of runoff as well as pollutant removal. The BMPs include conventional and innovative practices (e.g., permeable pavement, sheet flow to filter areas or open space, vegetated roofs, downspout disconnection, etc.). The method also incorporates built-in incentives for environmental site design, such as forest preservation and the reduction of soil disturbance and impervious surfaces. This methodology was tested in numerous site-plan workshops held across Virginia by DCR and the Virginia chapter of the American Society of Civil Engineers.

There are now two spreadsheets, one for new development and one for redevelopment projects. There are also accompanying explanatory documents, including (1) a methodology Cover Sheet; (2) a process flow chart (document A); (3) a document providing guidance regarding assigning land cover values; (4) concise BMP design tables for use in applying the spreadsheet; (5) and explanatory documentation (documents B and C for new development spreadsheet, and documents B-R and C-R for the redevelopment spreadsheet).

Technical Memo (April 2008)
New development spreadsheet (December 2009)
Redevelopment spreadsheet (December 2009)
Methodology cover sheet
Process flow chart (Document A) (December 2009)
Guidance regarding assigning land cover values
Concise BMP design tables for use in applying the spreadsheet
Explanatory documentation for new development
- Spreadsheet Instructions (Document B) (December 2009)
- Runoff Reduction Method Documentation (Document C) (December 2009)
Explanatory documentation for redevelopment
- Spreadsheet Instructions (Document B-R) (December 2009)
- Runoff Reduction Method Documentation (Document C-R) (December 2009)
Draft Stormwater Management Handbook Documents
- Example Solution for the Runoff Reduction Method (MS Excel file)
- NRCS 24 Hour Rainfall Depths and County Zone Maps (25MB)
  - List of Rainfall Depths
  - Albemarle County
  - Augusta County
  - Bedford County
  - Carroll County
  - Floyd County
  - Giles County
  - Grayson County
  - Greene County
  - Madison County
  - Montgomery County
  - Page County
  - Patrick County
  - Roanoke County
  - Rockbridge County
  - Rockingham County
  - Scott County
  - Warren County

To learn more about laws and code governing DCR, follow this link to the Division of Legislative Service's site. Search the site using keywords and phrases.

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