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Virginia Administrative Code
Title 9. Environment
Agency 25. State Water Control Board
Chapter 870. Virginia Stormwater Management Program (VSMP) Regulation
9/21/2023

9VAC25-870-98. Flooding.

A. Downstream properties and waterways shall be protected from damages from localized flooding due to changes in runoff rate of flow and hydrologic characteristics, including, but not limited to, changes in volume, velocity, frequency, duration, and peak flow rate of stormwater runoff in accordance with the minimum design standards set out in this section.

B. The 10-year postdeveloped peak rate of runoff from the development site shall not exceed the 10-year predeveloped peak rate of runoff.

C. In lieu of subsection B of this section, localities may, by ordinance in accordance with § 62.1-44.15:33 of the Code of Virginia, adopt alternate design criteria based upon geographic, land use, topographic, geologic factors, or other downstream conveyance factors as appropriate.

D. Linear development projects shall not be required to control postdeveloped stormwater runoff for flooding, except in accordance with a watershed or regional stormwater management plan.

Statutory Authority

§§  62.1-44.15:25 and 62.1-44.15:28 of the Code of Virginia.

Historical Notes

Former 4VAC50-60-98 derived from Virginia Register Volume 27, Issue 26, eff. September 13, 2011; amended and renumbered, Virginia Register Volume 30, Issue 2, eff. October 23, 2013.

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