RD396 - Study of the Subject Matter of Senate Bill 484 (2016) Relating to Stormwater Management Regulations
As requested pursuant to Rule 20 (o) of the Rules of the Senate of Virginia, the Department of Environmental Quality (DEQ), on behalf of the State Water Control Board, has studied the subject matter of Senate Bill 484 and offers the following:
The Virginia Stormwater Management Program regulations require use of the Virginia Runoff Reduction Method (VRRM) or another equivalent methodology approved by DEQ for compliance with the Part IIB water quality criteria. The VRRM is supported by stormwater research for runoff reduction and pollutant removal capabilities for stormwater Best Management Practices (BMPs). DEQ has developed two spreadsheets to assist in determining compliance with the VRRM; one for new development and a second spreadsheet for redevelopment. The spreadsheets are designed to allow users to see the benefits of environmental site design and various stormwater BMPs on a specific site.
On May 2, 2016, DEQ issued Guidance Memo No. 16-2001, which revised the VRRM compliance spreadsheets. The guidance memo is attached and contains a much expanded and more user friendly instructions and explanations of the spreadsheet logic, equations, and reference information. A copy of the guidance memo is also available online at: http://www.deq.virginia.gov/Portals/0/DEQ/Water/StormwaterManagement/VRRM/GM14-2001%20Virginia%20Runoff%20Reduction%20Method_V3.pdf The updated VRRM spreadsheets contain several new features, including:
• Summary land cover statistics including the composite runoff coefficient for the entire site in its developed condition, the pollutant load, and the corresponding treatment volume.
• The ability to evaluate the effectiveness of different BMPs and BMP combinations with respect to water quality compliance using up to five different drainage area tabs within a site.
• Summary information m each drainage area tab for the land cover, runoff volume and generated pollutant load, the BMPs selected, and the runoff volume and pollutant load reduced by the BMPs.
• Tracking of volume reduction in each drainage area tab for use in compliance with water quality control requirements.
• A summary compliance report for BMP implementation in each drainage area tab as well as overall site compliance.
If you have any questions or comments about the stormwater design criteria and the VRRM we are available to discuss them at your convenience. Please feel free to contact me anytime.
/s/ David K. Paylor
Director, Department of Environmental Quality