Required Site Design Measures for Small Projects and Detached Single-Family Home Projects (Provision C.3.i. Requirements Effective 12/1/12)

New stormwater requirements became effective on December 1, 2012 for development projects that will create and/or replace at least 2,500 square feet of impervious, but less than 10,000 square feet of impervious surface, and standalone single family homes that create and/or replace 2,500 square feet or more of impervious surface. These requirements are in the San Francisco Bay Region Municipal Regional Stormwater Permit (MRP) and are described below.

Projects shall need to incorporate one of the following site design measures if the project creates and/or replace at least 2,500 square feet of impervious, but less than 10,000 square feet of impervious surface, or it is a stand-alone single family home that creates and/or replaces 2,500 square feet or more of impervious surface.

  • 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.

Please find Fact Sheets with standard specifications in the “NPDES Provision C.3.i” table below OR Appendix L of the Countywide Program’s C.3 Technical Guidance.

BASMAA Landscape Dispersion Fact Sheet Fact sheet shows how to design your landscape to absorb runoff from impervious surfaces.
BASMAA Pervious Paving Fact Sheet Fact sheet shows how to design pervious pavement to allow water to flow through and seep into a base material (typically gravel or drain rock).
BASMAA Rain Barrel Fact Sheet Fact sheet shows how to install rain barrels and cisterns to capture stormwater runoff from rooftops and store it for later use.
BASMAA Rain Garden Fact Sheet Fact sheet shows how to construct rain gardens to reduce the amount of stormwater that runs off your property.