1. Vulnerability of Major Wastewater Facilities to Flooding from Sea-Level Rise August 21, 2008 Shaun O’Neil King County WTD

2. King County Wastewater System Serve 1.4 M people –2.4 M by 2030 420 sq.mi. 42 pump stations 19 regulator stations 353 miles of pipe 2” – 14’ in diameter 200 mgd average treatment 34 Local agencies contribute flow King County Sewerage Service Area a KING SNOHOMISH Seattle King County Sewerage Service Area a KING SNOHOMISH Seattle Puget Sound South Secondary plant CSO Plant Treatment plant CSO Treatment plant West Secondary plant King County wastewater treatment service area King County boundary New Secondary plant (2010)

3. Scope and Assumptions Facility Elevations Current Tide levels Future Tide Levels Storm Impacts Results Cal State LA

6. USGS University of Washington

7. Seattle Tide Gauge Data (January 1983–December 2001) Elevation (above NAVD88 zero feet) Highest observed water level (January 27,1983) 12.14 Mean higher high water (MHHW) 9.01 Mean high water (MHW) 8.15 Mean sea level (MSL) 4.29 NAVD 0.00 Mean lower low water (MLLW) -2.35 Lowest observed water level (January 4, 1916) -7.38 NOAA

9. Mean Sea Level Difference: for Seattle, WA 1983-2001 1960-1978 Difference: 14.58 ft. 14.40 ft. 0.18 ft. NOAA

10. IPCC, 2007

12. Puget Sound Sea-Level Rise Scenarios (Mote et al., 2008) ScenarioPredicted Sea-Level Rise 20502100 Very low sea-level rise—low-probability low-impact 3 inches (0.25 feet) 6 inches (0.50 feet) Medium sea-level rise (most likely)6 inches (0.50 feet) 13 inches (1.08 feet) Very high sea-level rise—low-probability high-impact 22 inches (1.83 feet) 50 inches (4.17 feet)

13. NASA

14. Zervas, C.E., 2007 Feet above NAVD 88 0’ Feet Above NAVD 88 0’

15. Annual Probability of Exceedance Feet above Unaffected Tide 1% (once in 100 years average)3.19’ 10% (once in 10 years average)2.79’ 50% (once every 2 years average)2.27’ 99% (once per year average)1.48’ Zervas, C.E., 2007

22. Next Steps Terrain analysis of five lowest sites and West Point Treatment Plant. Create tool to replicate Vulnerability Analysis for other agencies. Conduct analysis of impact of sea-level rise on system hydraulics. Include sea-level rise as a planning factor for future projects. Review sea-level rise literature every five years and coordinate with CSI Updates.

23. References Intergovernmental Panel on Climate Change (IPCC). 2007. Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Solomon, S., Qin, D., Manning, M., Chen, Z.,. Marquis, M., Averyt, K.B., Tignor, M. and Miller, H.L. (Eds.). Cambridge, UK, and New York, NY: Cambridge University Press. Mote, P., Petersen A., Reeder, S., Shipman, H., and Whitely Binder, L. 2008. Sea Level Rise in the Coastal Waters of Washington State. Report prepared by the Climate Impacts Group, University of Washington, Seattle, Washington, and the Washington Department of Ecology, Lacey, Washington. Zervas, C.E. 2005. Response of Extreme Storm Tide Levels to Long-Term Sea Level Change. Oceans, 2005, Proceedings of MTS/IEEE, 3, 2501-2506.

24. Questions?

25. Websites King County Climate Change with Vulnerable Facilities Analysis Paper - http://dnr.metrokc.gov/dnrp/climate-change/conference-2005.htm http://dnr.metrokc.gov/dnrp/climate-change/conference-2005.htm UW Climate Impacts Group - http://cses.washington.edu/cig/http://cses.washington.edu/cig/ Mote Paper - http://cses.washington.edu/db/pdf/moteetalslr579.pdfhttp://cses.washington.edu/db/pdf/moteetalslr579.pdf Puget Sound LIDAR Consortium - http://pugetsoundlidar.ess.washington.edu/About_PSLC.htm http://pugetsoundlidar.ess.washington.edu/About_PSLC.htm NOAA Tides and Currents - http://tidesandcurrents.noaa.gov/index.shtmlhttp://tidesandcurrents.noaa.gov/index.shtml Seattle Tide Gauge - http://tidesandcurrents.noaa.gov/station_info.shtml?stn=9447130+SEATTLE,+PUGE T+SOUND,+WA http://tidesandcurrents.noaa.gov/station_info.shtml?stn=9447130+SEATTLE,+PUGE T+SOUND,+WA IPCC - http://www.ipcc.ch/http://www.ipcc.ch/ Shaun O’Neil 206.684.1671 Shaun.O’Neil@kingcounty.gov