Vulnerability of Major Wastewater Facilities to Flooding from Sea-Level Rise May 14, 2008 Laura Wharton & Shaun O’Neil King County WTD

Background 2006 creation of King County Global Warming Team Executive orders: lower carbon emissions, through use of advanced technology; new energy policies and increased use of hybrid fleets/biodiesel Comprehensive strategy addressing both mitigation and adaptation King County Climate Plan issued February 2007

2007 King County Climate Plan  Includes both Mitigation and Adaptation  Includes all sectors of County activities  Id’s relevant activities  Includes goals, activities, milestones, measures  Requires annual status reports

Adaptation and Planning Response Support operational resilience of wastewater treatment facilities –Collaborate with climate science experts to develop reasonable regional assumptions for long-range planning purposes –Obtain more detailed local and regional climate information upon which to base planning assumptions (CIG report completed 2/08) –Provide consistency between multiple agencies and departments –Further understanding of future impacts and costs across agencies and departments

Adaptation and Planning Response Develop strategies to manage wet weather impacts of climate change to the sewer system –Identify WTD facilities affected by storm surge/sea level rise (above extreme high water) - Phase 1 Develop methodology to combine sea level projections + storm surge Conduct GIS based analysis Identify the impact threshold (problematic at what level) Characterize the impact (on-site, hydraulic, operational)

Barton Pump Station

Recommendations Terrain analysis of five lowest sites and West Point Treatment Plant. Review design for Brightwater sampling facility and flow monitor vault sites. Conduct analysis of sea-level rise impacts 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 conveyance system improvement schedules.

References Intergovernmental Panel on Climate Change (IPCC) 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 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 Response of Extreme Storm Tide Levels to Long-Term Sea Level Change. Oceans, 2005, Proceedings of MTS/IEEE, 3,