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Greening the Region Using Stormwater Infrastructure

Greening the Region Using Stormwater Infrastructure. May 7, 2014 Jim Simmonds King County Water and Land Resources Division Jim.Simmonds@kingcounty.gov. Stormwater Paradigm. Parcels Built Before Stormwater Controls Required. About three-fourths of urban lands lack stormwater facilities.

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Greening the Region Using Stormwater Infrastructure

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  1. Greening the Region Using Stormwater Infrastructure May 7, 2014 Jim Simmonds King County Water and Land Resources Division Jim.Simmonds@kingcounty.gov

  2. Stormwater Paradigm

  3. Parcels Built Before Stormwater Controls Required About three-fourths of urban lands lack stormwater facilities

  4. Check Dams Stormwater Retrofit Examples Bioswales Cisterns Ponds Pervious Pavement Green Roofs Rain Gardens

  5. Estimated Stormwater Needs • $3B - $15B for treatment in Puget Sound • Capital costs, no O&M, no land costs • $1.4B for Juanita Creek basin (7 sq miles) • Full lifecycle cost • $1.1B for 64 small basins in unincorporated King County • Full lifecycle costs

  6. Stormwater Retrofit Planning for WRIA 9 • $1M grant from EPA, $335K match • 4 years • Model stormwater retrofit needs in WRIA 9 • Work with stakeholders • Present retrofit options analysis to WRIA 9 Watershed Ecosystem Forum • Extrapolate cost estimates to all Puget Sound

  7. Project Benefits • Planning-level estimate of facility and funding needs • Cost vs stream improvement • Demonstrate use of modeling tools • Influence capital project planning • Influence future NPDES permits • Influence discussion on new funding

  8. Approach • Gather geospatial data about • existing stormwater facilities, soil, precipitation patterns, slope, impervious area, development type, land costs, stream channels • Conduct hydrologic modeling • Model hydrologic improvements with stormwater facilities

  9. Future Development 2007 Satellite-Derived Land Use (UW 2007) 2040 Simulated Land Use (Alberti 2009)

  10. SUSTAIN: System for Urban Stormwater Treatment and INtegration

  11. Modeling Approach • Study area: 278 mi2, 446 catchments • Model 135 hypothetical 100-acre catchments representing combinations of: • 5 generic land uses • 3 soil types • 2 slopes • 3 precipitation zones • 2 land costs

  12. SUSTAIN Optimization Target: Reduce Stream Flashiness High Pulse Count: Number of times mean daily flows ≥ high-flow threshold set at 2 X long-term mean daily flow rate

  13. High Pulse Count and Biology

  14. Addressing Redevelopment • Redevelopment improves stormwater management • Nearly ½ of project area to have new or re development by 2040 • More expected beyond 2040 • Decreases estimated need

  15. Addressing Climate Change • Three approaches for assessing impacts • Analysis of precipitation patterns for downscaled global climate model output • Impacts of climate change on hypothetical pond sizing • Impacts of climate change on high pulse count in hypothetical basin • Likely need about 10% more flow control, but model variability is large

  16. 2040 Potential B-IBI Scores No Stormwater Management Full Stormwater Management

  17. Policy and Planning Horizon are Everything • How stringent are stormwater requirements for redevelopment? • How aggressively do public programs build facilities? • How long in the future do we aim for success?

  18. What If? • Assume new and redevelopment builds on-site facilities and developers contributes funds to build off-site facilities (ponds) • Assume public funds used to build everything else • Assume all stormwater facilities built within either 30 years

  19. Annual Public Costs

  20. The Big Questions • How quickly do we want to improve stream flows and water quality? • To what degree do we want to improve stream flows and water quality? • Where does capital funding come from? • Where does operating funding come from?

  21. Project Team • Don Robinett, SeaTac • Ben Parrish, Covington • Chris Thorn, Auburn • Jeff, Burkey, Curtis DeGasperi, David Funke, Larry Jones, Chris Knudson, Beth leDoux, Doug Navetski, Elissa Ostergaard, Giles Pettifor, Dan Smith, Allison Vasallo, Mark Wilgus, Olivia Wright, King County • Rich Horner, ErkanIstanbullouglu, UW • Ed O’Brien, Mindy Roberts, Ecology • Dino Marshalonis, Michelle Wilcox, EPA • Tamie Kellogg, Kellogg Consulting

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