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T-1 Infiltration Tools, v3.01

T-1 Infiltration Tools, v3.01. Presented by Sean Penders (Caltrans) Eric Berntsen (SWRCB) Brian Currier (CSUS-OWP). Presented to Caltrans and RWQCB Staff May 10, 2013 Prepared by Caltrans and Office of Water Programs. Overview. Background

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T-1 Infiltration Tools, v3.01

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  1. T-1 Infiltration Tools, v3.01 Presented by Sean Penders (Caltrans) Eric Berntsen (SWRCB) Brian Currier (CSUS-OWP) Presented to Caltrans and RWQCB Staff May 10, 2013 Prepared by Caltrans and Office of Water Programs

  2. Overview • Background • Prioritizing soil-based BMPs in the Caltrans BMP Selection Process • Conceptual infiltration model review • Example: strip/swale and detention basin treatment train • Q&A

  3. Background • Sustainable BMP goals from EPA, FHWA, SWRCB, RWQCB, & Caltrans • District Design needs • Performance-based ranking for target design constituents using statewide studies confirmed that infiltration was a key variable for load reduction

  4. Background Consistency with Water Board Goals • Board resolution on sustainability • Caltrans MS4 NPDES permit • Based on the CGP Post Construction “Soil Quality” credit in the CGP Water Balance Calculator • Phase I & II MS4 http://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2008/rs2008_0030.pdf

  5. Background Caltrans Conditions and Applicability • Not for flood Analysis • Analyzing small storm sizes • Only for water quality BMP sizing • Tailored to Caltrans • Compacted fill • Motorist safety • Useful statewide

  6. Background Caltrans Design Process: Project Planning and Design Guidance (PPDG) • 1-acre net new impervious post-construction BMP threshold Hwy • 5000 sf non-hwy • PPDG, T-1 Checklist: Treatment BMP Selection • Performance-based ranking of BMPs • Requires infiltration calculation

  7. Prioritizing Soil-based BMPs T-1 Checklist Process Potential BMPs Identify special-cases Add special BMPs > 90 % strip/swales infiltration Add strips/swales yes Need Infiltration Prioritizing soil-based BMPs no > 90% treatment train infiltration no Add basin yes MEP BMP Selection no Add Tier 1 BMPs Two-tiered list Estimate infiltration Ranking Algorithm Select pollutant

  8. Prioritizing Soil-based BMPs T-1 Selection: Performance-Based Ranking Across Caltrans Studies Performance-Based Ranking of Treatment BMPs. CTSW-RT-10-239.01. February 26, 2010

  9. Prioritizing Soil-based BMPs Performance-Based Ranking Across Caltrans Studies Performance-Based Ranking of Treatment BMPs. CTSW-RT-10-239.01. February 26, 2010

  10. Conceptual Infiltration Model Review • No surface storage • Strips • Swales • Natural and amended conditions • Infiltration Trenches • With surface storage • Detention Basins • Infiltration Basins

  11. Conceptual Model No Surface Storage:Strips and Swales Infiltration Tool (SSIT) Native Soil Amended Soil Native Soil

  12. Conceptual Model With Surface Storage:Basin Infiltration Tool (BIT)

  13. Example Project: New Highway • 10 acres of new impervious surface • Limited area for a strip/swale and detention basin • Type B soil • ½ acre of pervious shoulder

  14. Example Strip/swale and Detention

  15. Native Soil, Rate-Based Estimate

  16. Example Amendment Input

  17. Example

  18. Example Adjust Soil Amendment • Use 9 inches instead of 4 to meet surface loading design requirements

  19. Example SSIT Results Page • Substantial benefits from amendment

  20. Example Adding a Downstream Basin

  21. Example Basin Size Reduced Based on Maximum Upstream Losses

  22. Example Basin Inputs • Enter available area (100 ft x 50 ft) • Verify soil infiltration rate

  23. Example BIT Results • 56% total treatment train infiltration! • 42% upstream infiltration + 58% basin treatment = 100% treatment!

  24. Consistency with Water Board Standards and Goals • Consistent with State Water Board resolution on sustainability (Resolution No. 2008-0030) • Caltrans MS4 NPDES permit • Based on the “Soil Quality” credit in the CGP Water Balance Calculator

  25. Links • Basin Sizer http://svctenvims.dot.ca.gov/wqpt/basinsizer.aspx • WQPT http://svctenvims.dot.ca.gov/wqpt/wqpt.aspx • Infiltration Tool http://www.dot.ca.gov/hq/oppd/stormwtr/t1.htm • PPDG • http://www.dot.ca.gov/hq/oppd/stormwtr/ppdg.htm • SWRCB http://www.waterboards.ca.gov/board_decisions/adopted_orders/resolutions/2008/rs2008_0030.pdf • Caltrans NPDES MS4 permit http://www.swrcb.ca.gov/water_issues/programs/stormwater/caltrans.shtml

  26. Questions and Comments

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