1. Stormwater and C.3 Overview Tom Dalziel, Assistant Manager Contra Costa Clean Water Program

2. Program’s C.3 web page www.cccleanwater.org/construction/nd.php www.cccleanwater.org/construction/nd.php www.cccleanwater.org/construction/nd.php The address is in the Guidebook and on the fact sheet The address is in the Guidebook and on the fact sheet Source for C.3 info and updates Source for C.3 info and updates Presentation slides will be posted next week Presentation slides will be posted next week

3. Provision C.3 Topics Effects of New Development on water quality Effects of New Development on water quality C.3 in a nutshell C.3 in a nutshell Why it’s called “C.3” Why it’s called “C.3” Regulatory background Regulatory background How we got to this point How we got to this point What’s special about Contra Costa’s approach to implementing C.3 What’s special about Contra Costa’s approach to implementing C.3 BMPs and IMPs BMPs and IMPs Objectives for today’s workshop Objectives for today’s workshop

4. Effects of New Development Page 15

5. Runoff Before Development

6. Runoff After Development

7. Effects of increased runoff Increased flows and more frequent flooding leads to… Increased flows and more frequent flooding leads to… Increased streambank erosion, which leads to… Increased streambank erosion, which leads to… “Hardening” to prevent erosion, which leads to… “Hardening” to prevent erosion, which leads to…

8. Loss of Stream Functions

9. C.3 in a nutshell Projects subject to C.3 must: Minimize imperviousness. Minimize imperviousness. Control potential pollutant sources. Control potential pollutant sources. Treat stormwater before discharge. Treat stormwater before discharge. Match runoff peaks and durations to pre-project conditions. Match runoff peaks and durations to pre-project conditions. Maintain treatment and flow-control facilities in perpetuity. Maintain treatment and flow-control facilities in perpetuity.

10. Where “C.3” comes from The California Regional Water Quality Control Board issued a permit… …requiring municipal governments to implement a comprehensive program to control stormwater pollutants. Municipal Maintenance Program Elements Illicit Discharge Prohibition Industrial Inspections Construction Site Inspections Public Outreach Permit Provision “C.3” requires municipalities to mandate runoff controls as part of their development review procedures.

11. Stormwater Regulatory History 1987 Congress adds Section 402(p) to Clean Water Act 1990 USEPA regulations require states to issue stormwater NPDES permits to large municipalities 1990 Regional Water Board issues first Bay Area stormwater NPDES permits 2000 State Water Resources Control Board “Bellflower decision” confirms municipalities must require new developments to treat runoff

12. C.3 Regulatory History 2003 Regional Water Board adds Provision C.3 to stormwater permit for Contra Costa municipalities 2005 Contra Costa municipalities begin requiring stormwater source control and treatment as a condition of approval for new developments 2006 July 12: Water Board adds flow-control requirements to permit 2006 August 15: C.3 threshold drops from one acre to 10,000 square feet of impervious area 2006 October 14: Flow-control requirements in effect

13. Contra Costa’s Approach Pro-actively assist developers to comply Pro-actively assist developers to comply Aim for countywide consistency Aim for countywide consistency Model Stormwater Ordinance Model Stormwater Ordinance Stormwater Control Plan required Stormwater Control Plan required Stormwater C.3 Guidebook Stormwater C.3 Guidebook Low Impact Development Low Impact Development Continuous Improvement Continuous Improvement Updates posted on the Program’s C.3 web page Updates posted on the Program’s C.3 web page

14. Low Impact Development (LID) Benefits: Low Impact Development (LID) Benefits: Remove pollutants Remove pollutants Mimic pre-development hydrology Mimic pre-development hydrology Program LID Strategy: Program LID Strategy: Quantify benefits so we can show compliance with the numeric criteria in the NPDES permit Quantify benefits so we can show compliance with the numeric criteria in the NPDES permit Create tools and procedures to make it easier to create and review LID designs Create tools and procedures to make it easier to create and review LID designs Low Impact Development and C.3

15. BMPs and IMPs Best Management Practices (BMPs): Best Management Practices (BMPs): Any procedure or facility designed to minimize the quantity of pollutants entering storm drains. Any procedure or facility designed to minimize the quantity of pollutants entering storm drains. Integrated Management Practices (IMPs): Integrated Management Practices (IMPs): Part of a Low Impact Development approach Part of a Low Impact Development approach Facilities that control flows and treat runoff Facilities that control flows and treat runoff Typically distributed throughout the site Typically distributed throughout the site Integrated into landscape and site design Integrated into landscape and site design Mimic pre-development hydrology Mimic pre-development hydrology Page 19

16. Objectives for Today Understand effects of hydrograph modification and get an introduction to stream stability analysis Understand effects of hydrograph modification and get an introduction to stream stability analysis Learn the advantages and methods of implementing Low Impact Development Learn the advantages and methods of implementing Low Impact Development Understand how C.3 fits into the development review process Understand how C.3 fits into the development review process Know how flow-control facilities are analyzed Know how flow-control facilities are analyzed Be able to use the Guidebook instructions and the Program’s IMP sizing tool to design projects Be able to use the Guidebook instructions and the Program’s IMP sizing tool to design projects Discuss how you can help the Contra Costa Clean Water Program help you implement C.3 Discuss how you can help the Contra Costa Clean Water Program help you implement C.3