Beginning February 15, 2005 new development and significant redevelopment projects that disturb 1 Acre or more of soil must incorporate water quality improvements. The “C.3? requirements are separate from, and in addition to, requirements for erosion and sediment control and for pollution prevention measures during construction.

Project site designs must minimize the area of new roofs and paving. Where feasible, pervious surfaces should be used instead of paving so that runoff can percolate to the underlying soil. Runoff from impervious areas must be captured and treated. The permit specifies ways to calculate the required size of treatment devices. Projects may also be required to detain or infiltrate runoff so that peak flows and durations match pre-project conditions. In addition, project applicants must prepare plans and execute agreements to ensure the stormwater treatment and flow-control facilities are maintained in perpetuity.

WHAT'S NEW

• C.3 Process Flowchart
• Stormwater Managment Exhibit Notes
• Stormwater C.3  Guidebook 5th Edition (October 20, 2010). Contra Costa County C.3 Webpage
• Guidebook  Appendix B: Soils, Plantings and Irrigation for Bioretention Facilities (January 21, 2009)
• Model Stormwater Facilities Construction Inspection  Checklist (February 21, 2009)
• Model Stormwater Facility Operation and Maintenance  Verification Report form (February 21, 2009)