Just in Time for Winter Rains
Just in Time for Winter Rains
New Stormwater Requirements for Small Projects
by Laura Prickett, AICP
With winter storms making their annual return to Northern California, it’s a good time to focus attention on what happens to rainwater after it washes the dirt and grime off of pavements and rooftops. You may have already started including rain gardens, pervious paving, and cisterns in project designs, and you probably are familiar with the importance of stormwater infiltration to protect our local creeks from runoff pollution that flows from “impervious surfaces”. But did you know that, effective December 1, 2012, these designs are mandatory in much of the San Francisco Bay Area?
Where do the New Requirements Apply? The new requirements are in the Municipal Regional Stormwater Permit (MRP), which applies to all municipalities and unincorporated county areas in Alameda, Contra Costa, San Mateo and Santa Clara Counties (except southern Santa Clara County), as well as the Cities of Fairfield, Suisun, and Vallejo.
Which Projects are Affected? Within jurisdictions subject to the MRP, the requirements apply to the following project categories:
- Projects that create and/or replace 2,500 to 10,000 square feet of impervious surface,
- Individual single family home projects that create and/or replace 2,500 square feet of impervious surface, or more.
What about Larger Projects? Stricter requirements apply to the following project categories:
- Projects that create and/or replace 10,000 square feet or more of impervious surface (individual single family home projects are assumed to have less impact than other project types and are exempt from the stricter requirements).
- Projects in four land use categories (restaurants, gas stations, auto service facilities, and parking lots) that create and/or replace 5,000 square feet or more of impervious surface.
What are the New Requirements? Projects subject to the new requirements must implement at least one of the following stormwater “site design measures:”
- Direct roof runoff into cisterns or rain barrels for use.
- Direct roof runoff onto vegetated areas.
- Direct runoff from sidewalks, walkways, and/or patios onto vegetated areas.
- Direct runoff from driveways/uncovered parking lots onto vegetated areas.
- Construct sidewalks, walkways, and/or patios with permeable surfaces.
- Construct bike lanes, driveways, and/or uncovered parking lots with permeable surfaces.
What Resources are Available? The Bay Area Stormwater Management Agencies Association’s (BASMAA) regional design guidance fact sheets are listed below (available for download):
- Landscape designs for stormwater management,
- Rain gardens,
- Pervious paving,
- Rain barrels and cisterns.
Check with staff of the applicable municipality to obtain any county-specific or municipality-specific guidance.
The permit requirement is in Provision C.3.i of the MRP, available for download here.
Laura Prickett is a Senior Planner with EOA, Inc. She chairs the Land Use Subgroup of the Santa Clara Basin Watershed Management Initiative and provides permit compliance support to the Santa Clara Valley Urban Runoff Pollution Prevention Program, San Mateo Countywide Water Pollution Prevention Program and the Clean Water Program – Alameda County.
Posted in Design, Sustainability. Tags: Alameda County, Contra Costa County, Fairfield, MRP Municipal Regional Stormwater Permit, Planning, public space, Residential Design, San Mateo County, Santa Clara County, Small Projects, stormwater, Suisun, Sustainability, Urban Design & Transportation, Vallejo.