New Stormwater Control Requirements, Part 2
In our ongoing efforts to
keep our clients informed about recent developments, we follow up our last issue on the new Statewide General Construction Storm Water Permit with
information about the recently adopted Municipal Regional Stormwater Permit
(MRP). Other Breaking News: On
March 3, 2010 the California Fish and Game Commission formally listed the California
tiger salamander (CTS) as a Threatened species, pursuant to the California Endangered Species Act
(CESA). Although the CTS is
already protected under the federal Endangered Species Act (ESA), the
California listing will add to the regulatory hurdles for projects affecting CTS
habitat, particularly if pending legislation (AB 2420) passes.
New Feature: Our previous eAlerts are now archived at: DHA eAlerts Archive
As always, let us know if there's anything else we can do to help lighten your work load.
Doug Herring, AICP
[All photos Copyright 2010 by Douglas Herring]
New Municipal Stormwater Permit Requirements
On October 14, 2009 the San
Francisco Bay Regional Water Quality Control Board (RWQCB) adopted a revised
Municipal Regional Stormwater Permit (MRP)
. The MRP regulates stormwater
discharges pursuant to the National Pollutant Discharge Elimination System
(NPDES). The new MRP consolidates
and supersedes previous permits issued to cities, towns, and local agencies in
Alameda, Contra Costa, San Mateo, and Santa Clara counties, as well as the
Solano County cities of Fairfield, Suisun City, and Vallejo. For a copy of the MRP, go to SF RWQCB
In February 2003 the San
Francisco Bay RWQCB added Provision C.3 to the NPDES stormwater permits issued
to the municipalities under its jurisdiction. Intended to reduce the introduction of urban pollutants into
San Francisco Bay and the creeks, streams, lakes, and other water bodies in the
region, Provision C.3 requires the onsite treatment of stormwater prior to its
discharge into downstream receiving waters. (These requirements are in addition to the new NPDES
requirements for erosion and sedimentation controls during project construction
that were addressed in the previous DHA eAlert).
Under the old permit, projects
subject to Provision C.3 were required to capture and treat onsite all
stormwater from the site prior to its discharge, including rainwater falling on
building rooftops, to the "maximum extent practicable." This was accomplished via:
- Treatment controls, such as bio-retention areas, vegetated swales,
and infiltration trenches;
- Source control features designed to keep pollution away from stormwater, such
as trash and designated wash areas that are plumbed to the sanitary sewer
- Site Design features reducing impervious areas, increasing pervious
areas, and utilizing landscaped areas in between impervious areas as a storm
drainage treatment feature; and
- Hydrograph Modification
Management, also called Hydromodification
Management (HM), to ensure that runoff from developed areas matches the flow volume
and rate of the pre-project runoff.
In brief, the revised Provision C.3 requirements of the new MRP
- For some land uses-including gas stations, restaurants,
and uncovered parking lots-the threshold for onsite treatment requirements
drops to 5,000 (from 10,000) square feet of impervious area created or
- Applicants must evaluate feasibility of infiltration or
- Applicants may propose to provide treatment of runoff
from an equivalent amount of impervious area, subject to conditions.
- Use of below-ground vaults and filters is still
restricted (exceptions to be updated).
- Low-Impact Development (LID) design procedures and
criteria for treatment and flow-control facilities will stay the same. However, although many municipalities
in the Bay Area have, until now, allowed non-LID designs (including detention
basins and proprietary devices) to treat runoff, under the MRP, these
municipalities must now require LID be used to reduce runoff before discharge
- Biotreatment (filtering stormwater through vegetation
and soils before discharging to the storm drain system) and/or vault-based
treatment measures will be allowed only where LID methods such as harvesting
and reuse, infiltration and evapotranspiration are infeasible at the project
- Applicants for approval of projects smaller than the
threshold are encouraged to include site design measures to reduce runoff and
source control measures to reduce pollutants in runoff.
When Will the New Permit Take Effect?
- Projects larger than 2,500 square feet of impervious
area must include at least one site design feature to reduce runoff.
Most of the new MRP requirements are phased in through
2012. Project applicants should assume new
projects that start after January 1, 2010 will be subject to the new MRP. As of the date of this eAlert, most Bay
Area jurisdictional agencies have not updated their respective guidance
documents to incorporate the requirements of the new permit.
We have prepared a white paper
providing more detail on the new requirements
, which we're
providing free of charge to our readers.
Among other information, it includes a table summarizing the changes to the stormwater requirements. You can download the document at Stormwater White Paper #4
|Who Is Douglas Herring & Associates?
Douglas Herring & Associates (DHA) works with public agencies, developers, and other businesses
in California to expertly obtain the environmental and planning approvals needed to move projects from the conceptual stage to physical, benefit-generating reality in an efficient and cost-effective manner. Since 1997, DHA has helped dozens of California cities and counties and scores of other businesses and organizations save money while obtaining high-quality planning and environmental analysis services necessary to get their projects expeditiously approved and built. Learn more on our website: Douglas Herring & Associates
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