HD2 - Application of the Postdevelopment Stormwater Management Technical Criteria, as Established in the Virginia Stormwater Management Program Regulations, in Areas with a Seasonal High Groundwater Table (HJR 587, 2015)


Executive Summary:
The 2015 Virginia General Assembly passed House Joint Resolution Number 587 (HJR 587). The resolution as passed states in part:

That the Department of Environmental Quality be requested to study the application of the postdevelopment stormwater management technical criteria, as established in the Virginia Stormwater Management Program Regulations, in areas with a seasonal high groundwater table.

The resolution specifies that the Department of Environmental Quality (DEQ) evaluate the existing design specifications for best management practices (BMPs) listed on the Virginia Stormwater BMP Clearinghouse and recommend design specification revisions to allow the effective use of these BMPs in areas with a seasonal high groundwater table (SHGT), if applicable. The purpose of this effort is to achieve greater flexibility in meeting the stormwater management requirements in areas with a SHGT.

This report summarizes the work completed during the first year of the study, where DEQ reviewed documents to further understand the issues associated with a SHGT. This effort included providing recommendations for determining areas with a SHGT and learning how SHGTs affect the function of stormwater BMPs. As part of the study, DEQ has performed a literature review of stormwater BMPs to further understand the potential issues of locating BMPs in areas with a SHGT.

The first part of this report defines a SHGT and describes the requirements of the Virginia Stormwater Management Program (VSMP) Regulations (9VAC25-870-10 et seq.). The report discusses the connection between the management of water quality and quantity and the importance of BMP volume reduction benefits to meet the postdevelopment stormwater management requirements. It highlights how other states manage stormwater in areas with a SHGT and proposes potential modifications to existing BMPs for use in areas with a SHGT. The report concludes by providing the background and goals for work to be accomplished during the second year of the study.