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Tentative Draft Construction General Permit: Approach and Overview

June 4, 2008 – Public Hearing State Water Resources Control Board Division of Water Quality Storm Water Section. Tentative Draft Construction General Permit: Approach and Overview. Construction Activity Threats.

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Tentative Draft Construction General Permit: Approach and Overview

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  1. June 4, 2008 – Public Hearing State Water Resources Control Board Division of Water Quality Storm Water Section Tentative Draft Construction General Permit:Approach and Overview

  2. Construction Activity Threats • Two-fold – construction projects over an acre have the potential to cause impacts to our beneficial uses of water both during and after the project. • During – potential for sediment and erosion discharges. • After – potential for hydromodification impacts as a result of how the new landscape functions.

  3. Construction WQ threats = + +

  4. Staff Permit Reissuance Goals(from pre draft, April 2007) • Adopt a risk-based permit approach • Improve “performance” measurement of program • Establish a standard to avoid, minimize and mitigate hydromodification impacts associated with all new and re-development projects triggering the construction activity permit.

  5. Risk Approach • Tentative permit has a detailed risk approach that separates risk into two functions - sediment discharge risk and receiving water risk • Tentative permit matches “implementation levels” to overall risk, which is based on a combination of the two functions, above.

  6. Performance-based Permit • Direct requirements (vs. ones embedded in the SWPPP) = more enforceable, easier to enforce and more transparent for public • Numeric effluent limits for turbidity set at minimum technology level = more enforceable, easier to enforce • Monitoring requirements designed to assess various levels of outcomes and outputs

  7. Runoff Reduction Measures • Aimed at parts of State without MS4 coverage • Water balance approach – match pre-construction • Represent an interim step towards more specific hydromodification standards • Credits will reduce runoff and provide multiple, community benefits

  8. Permit Support Efforts • Public process and e-Business solution • Screens are being designed and process is on track • Built in compliance with federal rule on electronic reporting (CROMERR) • CGP Training partnership • Being co-led by staff and CASQA • Includes most interests and 15+ participants from around the State

  9. Stakeholder Process • Stakeholder input beginning in April 2007 – pre-draft permit • Multiple opportunities for comments and suggestions • Provided invaluable input to the tentative permit • Staff committed to continued development and growth of partnerships and relationships w/ stakeholders

  10. Patrick Otsuji Supervisor NOI Processing E-Business Project Co-manager (916) 341-5292 potsuji@waterboards.ca.gov Leo Cosentini Industrial Permit Writer E-Business Project Co-manager (916) 341-5524 lcosentini@waterboards.ca.gov Laurel Warddrip Construction Permit Writer (916) 341-5531 lwarddrip@waterboards.ca.gov Annalisa Kihara Construction Permit Writer (916) 324-6786 akihara@waterboards.ca.gov Eric Berntsen Construction Permit Writer (916) 341-5911 eberntsen@waterboards.ca.gov Greg Gearheart Program / Project Manager (916) 341-5892 ggearheart@waterboards.ca.gov Who are we? DWQ Permit Team

  11. Hydromodification Impacts

  12. Hydrologic Cycle From Lake (2004)

  13. Pre-development Aggradation Phase • hillslope erosion is largest sediment source • width:depth may increase or stay constant • cross-sectional area increases Erosional Phase • channel erosion is largest sediment source • width:depth increase eventually • cross-sectional area increased to accommodate larger bankfull discharge

  14. After Lane (1955) as cited in Rosgen (1996)

  15. Urbanization tends to increase storm water runoff: • peak flows • volume • frequency Post-Develop. Increase in Bankfull Discharge Pre-Development Runoff Time From Haltiner (2006)

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