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City of Spokane Stormwater

City of Spokane Stormwater. Spokane River Forum Conference March 26, 2013. Municipal Separate Storm Sewer System (MS4). About 1/3 of City 130 outfalls. Spokane’s Stormwater History. 1890. 1900. 1920. 1940. 1950. 1960. 1970. 1980. 1990. 2000s. Spokane’s Stormwater History. 1980s.

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City of Spokane Stormwater

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  1. City of Spokane Stormwater Spokane River Forum Conference March 26, 2013

  2. Municipal Separate Storm Sewer System (MS4) • About 1/3 of City • 130 outfalls

  3. Spokane’s Stormwater History 1890 1900 1920 1940 1950 1960 1970 1980 1990 2000s

  4. Spokane’s Stormwater History 1980s Oldest System Modern Practice

  5. Regulatory Framework • Less stringent regulation than wastewater • Non-numeric standards • BMPs • First Phase II NPDES permit: 2007 • Public Education and Involvement • Illicit Discharge Detection and Elimination • Construction stormwater controls • Post-construction stormwater management • Municipal Pollution Prevention and Good Housekeeping

  6. Regulatory Framework • Second Phase II NPDES permit cycle: 2014 • Enhances existing requirements • Adds regional effectiveness studies • Requires jurisdictions to “allow” low impact development • Require developments to retain on-site runoff from the 10-year storm event

  7. Low Impact Development (LID) • EPA: Green Infrastructure • Stormwater Management • Retention and infiltration • Storm gardens, green roofs, permeable pavement • Land Use Management • Preservation of natural features • Minimize construction disturbance area • Minimize impervious area Seattle SEA Streets Reduced runoff by 99% Bioretention Cells Reinforced Grassy Shoulders Reduced Street Width (11% less impervious area) No curbs

  8. Lincoln SURGE • Spokane Urban Runoff Greenways Ecosystem • Storm garden bio-infiltration cells • Treated stormwater flows to Cannon Hill Park Pond

  9. Broadway SURGE • Constructed 2010 • Bio-infiltration cells (storm gardens) • Permeable sidewalk • Urbanized area • Infiltration

  10. Hazel’s Creek • LID demonstration site and regional stormwater facility at 42nd and Freya

  11. Eastern WA LID Guidance Manual • Ecology grant awarded to Spokane County • Due date: June, 2013 • Eastern WA Phase II Jurisdictions • Washington Stormwater Center: www.wastormwatercenter.org • Public Comment • Interactive educational website

  12. City of Spokane and LID • PCB Consent Decree - Supplemental Environmental Project I: LID • Formation of Internal LID Subcommittee and Technical Advisory Committee • Educational materials • Utility Bill Insert • Brochure • Website: www.spokanewastewater.org/LID.aspx • Formation of Stakeholders Group • Draft ordinance with monetary or other incentives to City Council by August 2013

  13. Draft LID Incentives Ordinance • Reference the Eastern WA LID Guidance Manual • Streamline permitting process • Guidance on what LID technologies are available and suitable for Eastern Washington • Assess existing City code • Refer to ordinances applicable to LID

  14. Polychlorinated Biphenyls (PCBs) • What are PCBs? • Man-made compounds • “Banned” in 1977 but sources remain • Doesn’t break down readily • 209 Congeners • Why are we concerned? • Spokane River out of compliance with standards • Ecology sampling found PCBs in City of Spokane stormwater and CSO • Carcinogen that accumulates in food chain • What are we doing? • City of Spokane: PCB Consent Decree and permit-required wastewater monitoring • Spokane River Regional Toxics Task Force

  15. PCB Investigations Drywells Union Stormwater Basin CSO 34

  16. Catch Basin Sediments • Sample and analyze for PCB Aroclors and Congeners

  17. PCB Remedial Maintenance • Review Aroclor analysis results • Residential cleanup std. 1.0 mg/kg • Remove all sediments from catch basins • Dump on separate pad, mix with sawdust • Haul to lined cell at landfill

  18. Catch Basin (CB) Sediments

  19. Stormwater Characterization: Union Basin • Automatic flow-weighted composite sampling

  20. Stormwater Characterization: Union Basin • Goal: 6 samples per site • Wet season 2012-2013 • Event mean concentration • Compare congener patterns • Compare to previous samples (Ecology) Level Flow Rate Sample Aliquots

  21. Stormwater Characterization : Washington Basin • Integrated Plan • Basin priority • Total PCB load greater than Union basin? • Sampling spring 2013

  22. Stormwater Monitoring: Cochran Basin • Samples collected wet season 2012-2013 • DO TMDL-related parameters • BOD, phosphorus, ammonia • Metals • Suspended solids • Fecal Coliform • Total Coliform • PCBs • Flow rate and volume

  23. Stormwater Monitoring: Cochran Basin • Integrated Plan • Flow Volume • Pollutant concentration • Comparison to CSOs • NPDES Permit and DO TMDL • Estimate pollutant concentrations in typical City stormwater

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