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Adaptive Stormwater Management at an Industrial Site with Numeric Effluent Limits Sa

Adaptive Stormwater Management at an Industrial Site with Numeric Effluent Limits Santa Susana Site. Brandon Steets, P.E. & Megan Otto, P.E., Geosyntec Consultants Jonathan Jones, P.E., Wright Water Engineers

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Adaptive Stormwater Management at an Industrial Site with Numeric Effluent Limits Sa

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  1. Adaptive Stormwater Management at an Industrial Site with Numeric Effluent LimitsSanta Susana Site Brandon Steets, P.E. & Megan Otto, P.E., Geosyntec Consultants Jonathan Jones, P.E., Wright Water Engineers Robert Pitt, Ph.D., P.E., BCEE, D. WRE, University of Alabama

  2. Outline • Santa Susana Site (SSS) introduction • Regulation of SSS stormwater • Outfalls 008 and 009 • Expert Panel scope of work • BMP solutions • BMP Site Ranking Methodology • New BMP recommendations • Lessons learned

  3. Site Introduction • 2800-acre former federal government rocket engine testing and energy research facility (1950-1988) • Owned by the Boeing Company (post-1966) and the U.S. Government • Activities currently limited to demolition, remediation, and restoration • Future parkland and open space Astronaut Buzz Aldrin at SSFL (Ref: Rocketdyne Archives)

  4. Santa Susana Site Calleguas Creek Los Angeles River Pacific Ocean

  5. Regulation of SSS Stormwater • Stormwater discharges are regulated by the Los Angeles Regional Water Quality Control Board (LARWQCB) through an individual NPDES permit, which requires: • Composite discharge sampling during storms, and • Compliance with very protective Numeric Effluent Limits (NELs) • NELs for a wide range of constituents including: • Dioxins (TCDD TEQ): 2.8x10-8µg/L • Total Lead: 5.2 µg/L • Total Copper: 14 µg/L

  6. Outfalls 008/009 Outfall Watershed

  7. Expert Panel Scope of Work • Independent Expert Panel was engaged with Regional Board consent to oversee stormwater planning and design work, as well as provide input on monitoring, source removal activities, and various NPDES permit issues • Mission: Improve stormwater quality at NPDES Outfalls 008 and 009 • Additional responsibilities include overseeing scientific studies and interfacing with the public on risk and science communication.

  8. Expert Panel Members • Jonathan Jones, Wright Water Engineers • Dr. Robert Pitt, University of Alabama • Dr. Bob Gearheart, Humboldt State University • Dr. Michael Josselyn, WRA Consultants • Dr. Michael Stenstrom, University California, Los Angeles

  9. Monitoring Locations LEGEND 16 background sites and 68 potential BMP subareas monitored 2010 - 2012 Potential BMP subarea site Stormwater background site Outfall monitoring site

  10. Expert Panel Developments • Media Performance Testing – presented at CASQA 2009 • New Source, Erosion and Treatment Controls – presented at CASQA 2011 • Subarea monitoring and BMP siting prioritization methodology – presenting now! • First some treatment control performance monitoring results and progress on new treatment control installations

  11. Treatment Controls 13 culvert modifications

  12. CM-9 Performance

  13. Lower Lot Biofilter Construction in progress!

  14. Lower Lot Biofilter

  15. Northern Drainage Restoration, Mitigation & Monitoring Plan: Channel Stabilization Measures Vegetated riprap suggested for locations where armored toe protection is necessary. Check structures within main and side channels for sediment control Energy dissipation aprons at erosive culvert outlets.

  16. BMP Subarea Ranking Methodology • Innovative, statistically rigorous approach • Rank potential BMP subarea monitoring sites based on comparisons of: • Stormwater subarea concentrations with NPDES permit limits • Stormwater subarea particulate strengths with stormwater background particulate strengths • Monitoring locations were scored based on number and percent of samples above NPDES permit limits and/or background • Locations then ranked based on scores, and top locations identified • Best professional judgment for BMP recommendations • Process to be repeated annually through 2014

  17. Example: Based on weight alone, Site A would be prioritized over Site B. Site A: n = 10, m = 7  WeightA = 0.83 Site B: n = 14, m = 2  WeightB = 0.01 17

  18. Basic Approach (example) Second priority Not priority Highest priority Third priority

  19. Dioxin (TCDD TEQ) • Background subareas exceed NPDES Permit Limit • BMP subareas greater than Outfalls • TSS/erosion is not always the issue TCDD TEQ (ug/L) TCDD TEQ Particulate Strength (mg/kg)

  20. 2011/2012 Ranking Results

  21. Water Quality Improvements • Demonstrated by ranks, pre- and post-BMP modification (filter fabric added to CM weir boards; helipad sand bag berm constructed) • Limited to sites with at least 2 samples Better water quality

  22. Water Quality Improvements • Demonstrated by ranks, comparing influent and effluent. • Limited to sites with at least 2 samples. Better water quality *Average of impacted B1 influent streams

  23. New BMP Recommendations • BMPs were chosen for implementation at six of the top seven highest ranked subareas, with multi‐constituent scores ranging from 0.63 to 0.94. • Selected sites were included among the top-ranked sites that were: • Ranked first through fourth for metals and dioxins; • Had detections of the 2,3,7,8‐TCDD dioxin congener, which is typically associated with anthropogenic sources; and • Had the highest observed dioxin concentrations (noting that the scores do not explicitly account for concentration magnitudes, but rather account for frequency of exceeding the concentration‐based background and permit limit thresholds).

  24. New BMP Recommendations ELV/CM1 AREA B1 AREA CM9 AREA 24-INCH CULVERT DRAINAGE AREA 41 to 87% of dioxin load reduction addressed by BMPs recommended to treat 11% of the total 009 drainage area

  25. Public Involvement Process • Boeing and Panel are committed to public involvement and transparency through regular meetings and tours • Panel has been open to direct communication, thus building confidence and trust • Last public tour: April 2012 • Last Board staff tour: August 2012

  26. Lessons Learned • Robust statistical BMP ranking methodology applicable to other sites! • NEL compliance is a significant challenge with complications • Ubiquitous background sources (atmospheric inventory and soils) • Multiple landowners (NASA & Boeing) • Multiple jurisdictions & agency involvement (often hinders progress) • Unknown/variable performance of passive treatment systems • Implementability at point of compliance

  27. On the other hand… • NELs may have a positive side (assuming limits are scientifically based and achievable) • They provide certainty in the measurement metric • But if you have NELs, why is a SWPPP also necessary? • Why tell dischargers WHAT they need to meet as well as HOW they need to do it?

  28. Acknowledgements • The Boeing Company • Debbie Taege, Environment, Health & Safety – Environmental Remediation • Paul Costa, Environmental Protection Manager • NASA • Pete Zorba • Geosyntec Consultants • Paul Hobson • Dan Bourdeau • Judd Goodman

  29. Q&A SSFL Surface Water Expert Panel work products can be found at: http://www.boeing.com/aboutus/environment/santa_susana/water_quality.html 29

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