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Summary
Staff Report:
Subsection 3
of Section 204.2 provides that all stormwater generated by
new development shall not be discharged into a
jurisdictional wetland or local water body without adequate
treatment. The standard for adequate treatment has been the
use of a vegetative filter strip of about 25 feet in width
to filter out pollutants and particulate matter prior to the
water entering the wetland or water body. A similar
provision was part of the draft Virginia Stormwater
Management Model Ordinance at the time the County adopted
its Stormwater Management Ordinance (and this provision) in
2002. The Stormwater Management Ordinance was subsequently
incorporated into an overall Design Standards Manual. The
State eliminated this provision from their model ordinance,
as the Corps of Engineers and the Department of
Environmental Quality have oversight related to impacts to
wetlands and water bodies. The DEQ permits have a clause
in them that requires pre-treatment of surface water runoff
prior to entering into regulated wetland areas.
Since
adoption of this provision in 2002, it has been interpreted
as including both point source and non-point source
discharges into wetlands. The non-point sources are
primarily lawns and yards associated with residential
development. This has shown to be problematic for
residential projects, such as Brookside, where there are a
considerable amount of wetlands and they have already paid
for or mitigated their impacts to the wetlands in accordance
with a Memorandum of Understanding with the Corps of
Engineers.
This proposed amendment clarifies the requirement for
adequate treatment for point source discharges. Having
pre-treatment of stormwater runoff prior to being discharged
into jurisdictional wetlands is a good practice because it
helps to preserve the overall health of the ecosystem as
well as the vibrancy of the wetlands. To overload them with
concentrated pollutants suspended in stormwater runoff that
will primarily be collected from roadway areas and/or other
impervious areas would contribute to the wetlands premature
degradation and possible destruction. In addition,
pre-treatment will allow for screening out trash, debris,
and other large material, as well as for initial filtering
of other smaller suspended particulate matter in the runoff
that over time will eventually choke the wetlands ability to
thrive.
The addition of the point source language in our Design
Standards Manual reinforces the importance of pre-treatment
in the preservation and protection of these wetland areas.
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