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What Does MS4 Mean to You? A study of sewer and storm drain cross contamination

What Does MS4 Mean to You? A study of sewer and storm drain cross contamination. Presented by Bryn Evans. What will we talk about? A little about surface water quality regulations What a sewer agency is doing about them. MS4 and Sanitary Sewer. The goal: A look at future regulations

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What Does MS4 Mean to You? A study of sewer and storm drain cross contamination

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  1. What Does MS4 Mean to You? A study of sewer and storm drain cross contamination Presented by Bryn Evans

  2. What will we talk about? A little about surface water quality regulations What a sewer agency is doing about them MS4 and Sanitary Sewer • The goal: • A look at future regulations • Start thinking of how MS4 might affect sewer agencies…

  3. History Cuyahoga River 1969

  4. Clean Water Act Regulatory Timeline Point Sources POTWs Industry 1970 1980 1990 2000 2010 Construction Industrial Stormwater CWA amended(1987) Phase I MS4s Phase II MS4s

  5. Define MS4

  6. Municipal Separate Storm Sewer System (MS4) • Pipes • Gutters/inlets • Channels • Outfalls

  7. Municipal Stormwater Timeline Monitoring, Program Development Monitoring, Pilots, Enhancement, Implementation Monitoring, Pilots, Program Enhancement 1990 2000 2010 2020

  8. Watershed-based Numerical goal compliance point Bacteria is a priority pollutant ‘New’ Stormwater (MS4) Permit

  9. MS4 Water Quality Improvement Plan(s) • Source assessment • MS4 discharge-focused • Implementation strategies

  10. City of Santa Barbara Studies Bacteria in storm drain Human-specific Sewer exfiltration shown to be source Are Sewers an MS4 Bacteria Source? (Sercu et al. 2011, ES&T)

  11. San Diego County Application

  12. Highly Urbanized Area

  13. Sewer Exfiltration/MS4 Infiltration Pilot Study • Evaluate small sub-watershed area • Identify potentialareas of: • Exfiltration • and – • Infiltration • Determine frequency • Prioritize potential next step implementation

  14. Pilot Study Phased Approach • Each phase narrows search • Ph I – “Desktop” Portion (GIS, rec dwgs, CCTV) • Ph II – Field Investigation (CCTV Storm Drains) • Ph III – Field Testing (dye, soil, sampling) • Ph IV – Pipe Repair/replacement

  15. “Desktop” Investigation • Contributing Factors • Pipe crossings • Vertical separation • Sewer pipe condition • Storm drain Material/Size • Soil type

  16. Sewer Collection System Watershed Study Area Legend Sewer Pipe

  17. Sewer and Storm Drain System • Investigate: • Closed Pipe • And – • Open Channels Legend Sewer Pipe Open Channel Storm Drain Closed Channel Storm Drain

  18. Sewer/Storm Drain Crossings • GIS functions • Combine sewer data to storm drain and soil data Sewer Crossing Storm Drain

  19. GIS Selection Results • 107 (21%) sewer pipes selected for further study • GIS/data accuracy key

  20. Data Analysis • Compiled GIS data into categories • Missing Data  Use record drawings

  21. Scoring Matrix • 5 Categories, 12 sub categories • Weighted scoring

  22. Sewer Pipe Deficiency Assessment • Recent CCTV available for all mains • Identify defects relative to exfiltration

  23. Desktop Results • Based on scoring matrix • Narrow search down • 19of 507 (4%) sewer pipes above storm drain • 12 of 19 (2%) also cross storm drain • 6of 12 (1%) also have defect • 2of 6 (0.3%) also in sandy soil  highest rating

  24. Future Phases: Field Investigations

  25. Conclusions • Water Quality Improvement Plans required for municipalities • Bacteria is an MS4 issue • Sewer exfiltration may be a source • Process available to implement cost-effective pilot study • Allows prioritization of potential sites for next step implementation

  26. What Can You Do? • Understand applicable MS4 water quality issues • Communicate with stormwater department/ municipal agencies • Evaluate “potential sites” for exfiltration issues • Leverage resources within/outside agency

  27. Questions? Bryn Evans, CPSWQ Dudek bevans@dudek.com 760.479.4143

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