The City's NPDES Permit

The City's National Pollutant Discharge Elimination System (NPDES) permit requires the City and permit applicants to address storm water pollution issues in development of private and public projects. The requirements include implementation of Best Management Practices (BMPs) during construction and the use of Integrated Management Practices (IMPs) for permanent, post-construction controls to reduce pollutants discharged from the project site.

A Stormwater Pollution Prevention Plan (SWPPP) must be prepared to address construction related impacts.

Additionally, a Stormwater Control Plan (SCP) must be prepared for all projects that create or replace more than 10,000 square feet of impervious surface. The purpose of a SCP is to specify how the built project will incorporate site design characteristics, landscape features, and BMPs that minimize imperviousness, retain or detain stormwater, slow runoff rates, and reduce pollutants in post development runoff. The SCP must incorporate measures to treat stormwater runoff before it is discharged from the site. These treatment facilities must be designed to minimum criteria specified by the Regional Water Quality Control Board and must identify responsibility and a mechanism to ensure maintenance of the treatment facilities in perpetuity.

The SCP must be prepared in accordance with the Contra Costa Clean Water Program (CCCWP) C.3 Guidebook and must include all of the information described on the Stormwater Control Plan Checklist. For more information, please visit the Contra Costa Clean Water Program website.

Depending on the site and other conditions (e.g. clay soils or other poor percolation conditions), storm water management goals can be achieved by incorporating one or more basic elements, such as: infiltration, retention/ detention, and bio-filters.

Streets, parking lots, driveways, and landscaping areas can be designed to cause less impact in stormwater quality while providing aesthetic benefits. The following is a short list of endless possibilities:

  • Narrower streets
  • Hybrid parking lots that combine impervious aisles with permeable parking stalls,
  • Parking groves, concave medians,
  • Driveways using permeable materials such as unit pavers or crushed aggregate,
  • Infiltration trench or basin,
  • Wet ponds,
  • Constructed wetlands,
  • Extended detention basin,
  • Vegetated swales,
  • Vegetated buffer strips, and
  • Bio-retention landscaping.