Constraints, Criteria, and Standards

Constraints

-Economically feasible

-Aesthetically pleasing

-Improves quality of water discharged from Silver Lake to the Elizabeth River

-Reduces flooding between Duck Pond and Silver Lake

Criteria

-Prevents flooding of Duck Pond Drive during a 5-year storm event

-Costs less than $5,000 to implement, unless further money is granted by involved organizations once the design is approved

Structure Design Standards:

-In Section 11.3.9.2 of the VDOT Stormwater Management Details – R&B Standard SWM-1 provides the standards for a Precast Stormwater Management Drainage Structure. This detail can be modified to fit the Poplar Hall Project.

-In Section 11.3.9.2 of the VDOT Stormwater Management Details – R&B Standard SWM-DR, there are standards for stormwatwer drainage trash racks sizing and materials.

Floating Wetland Design Standards:

-Different manufactures of floating wetlands have their own set of standards; for example Floating Wetland Solutions provides a unique arrangement of standard island modules and submerged modules. The materials and vegetation added are also part of the companies' standards of production.

- Floating wetlands are not yet recognized by the Virginia Department of Environmental Quality as a Stormwater BMP, however they are sized and vegetated based on research and nutrient credit requirements. Pond coverage is directly related to percent removal of different nutrients and can earn stormwater credits.

Additional Standards:

-VA DEQ Stormwater Design Specification No. 2: Sheetflow to Vegetated Filter Strip or Conserved Open Space sets a minimum Vegetated Filter Strip width of 35 ft and identifies acceptable soil amendments and vegetation.

-In subsection 9VAC25-870-65 of the Virginia Stormwater Management Plan regulations created by the VA DEQ, bioretention cells have standards for sizing, dimensions, and water use for new implementations.