1. Greening the Region Using Stormwater Infrastructure May 7, 2014 Jim Simmonds King County Water and Land Resources Division Jim.Simmonds@kingcounty.gov 5/7/20141

2. Stormwater Paradigm Time PeriodParadigmDescription Prior to 1992Drainage Efficiency Convey water downhill as efficiently as possible 1992 – 2013Reduce New Impacts Reduce harm from new construction with flow control and treatment FutureReduce New and Existing Impacts Capture, infiltrate, detain, and treat stormwater everywhere to protect and rehabilitate receiving waters 5/7/20142

3. Parcels Built Before Stormwater Controls Required About three-fourths of urban lands lack stormwater facilities 5/7/20143

4. Stormwater Retrofit Examples 5/7/2014 Ponds Bioswales Check Dams Cisterns Pervious Pavement Rain Gardens Green Roofs 4

5. Estimated Stormwater Needs  $3B - $15B for treatment in Puget Sound Capital costs, no O&M, no land costs Capital costs, no O&M, no land costs  $1.4B for Juanita Creek basin (7 sq miles) Full lifecycle cost Full lifecycle cost  $1.1B for 64 small basins in unincorporated King County Full lifecycle costs Full lifecycle costs 5/7/20145

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 5/7/20146

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 5/7/20147

8. Approach  Gather geospatial data about existing stormwater facilities, soil, precipitation patterns, slope, impervious area, development type, land costs, stream channels existing stormwater facilities, soil, precipitation patterns, slope, impervious area, development type, land costs, stream channels  Conduct hydrologic modeling  Model hydrologic improvements with stormwater facilities 5/7/20148

9. Future Development 2007 Satellite-Derived Land Use (UW 2007) 2040 Simulated Land Use (Alberti 2009) 5/7/20149

10. SUSTAIN: System for Urban Stormwater Treatment and INtegration 5/7/201410

11. Modeling Approach  Study area: 278 mi 2, 446 catchments  Model 135 hypothetical 100-acre catchments representing combinations of: 5 generic land uses 5 generic land uses 3 soil types 3 soil types 2 slopes 2 slopes 3 precipitation zones 3 precipitation zones 2 land costs 2 land costs 5/7/201411

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 5/7/201412

13. High Pulse Count and Biology 5/7/201413 Biological ConditionB-IBI Range Excellent46 – 50 Good38 – 44 Fair28 – 36 Poor18 – 26 Very Poor10 – 16

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 5/7/201414

15. Addressing Climate Change  Three approaches for assessing impacts Analysis of precipitation patterns for downscaled global climate model output Analysis of precipitation patterns for downscaled global climate model output Impacts of climate change on hypothetical pond sizing Impacts of climate change on hypothetical pond sizing Impacts of climate change on high pulse count in hypothetical basin Impacts of climate change on high pulse count in hypothetical basin  Likely need about 10% more flow control, but model variability is large 5/7/201415

16. 2040 Potential B-IBI Scores No Stormwater Management Full Stormwater Management 5/7/201416

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? 5/7/201417

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 5/7/201418

19. Annual Public Costs CapitalOperation and Maintenance Inspection and Enforcement New and Re- Development $88M$4M$320M Roads and Highways $21M$19M$28M Everything Else $98M$89M$170M Total$207M$112M$518M 5/7/201419

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? 5/7/201420

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, Erkan Istanbullouglu, UW  Ed O’Brien, Mindy Roberts, Ecology  Dino Marshalonis, Michelle Wilcox, EPA  Tamie Kellogg, Kellogg Consulting 5/7/201421