Subject:
Title
New Stormwater Regulations & Location of Stormwater Facilities
Body
BACKGROUND SUMMARY:
The new stormwater regulations that went into effective July 1, 2014 apply to all land disturbing activities greater than 2,500 sf of land disturbance, including residential single lot tear-downs as well as all Town projects. The regulations, which are attached, include both water quantity and water quality components. These regulations require stormwater facilities must be either publicly or privately owned and maintained. But should private land development provide for stormwater management on private property or provide public infrastructure? Who should maintain a facility that collects or treats runoff from both public and private property? Staff hopes that these questions can be considered and answered during this work session.
OVERVIEW:
Water Quantity
Water quantity requirements have not changed significantly under the new regulations except for calculation and technical procedures used by engineers. Essentially a construction project must demonstrate post development runoff is non-erosive for the existing receiving channels or pipes for the 1-year storm event; and demonstrate flood protection during the 10-year storm event.
Water Quality
Water quality requirements can be met using various types of Best Management Practices (BMPs):
* Conventional (non-proprietary) BMP measures (ex.: infiltration trenches).
* Manufactured BMPs (proprietary). (ex.: Filterra tree-box curb inlets, or the underground Stormceptor that we use at the Northside Property yard which filters out trash, sediments, oils and grease.)
* Offsite credits (when the development is less than 5 acres.) The offsite credit program is administered and monitored directly by Virginia DEQ. Applicants must show Vienna staff proof of purchase prior to final plan approval or final occupancy in the case of single family re-builds.
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