Anacortes, Washington: Enhancing Water Treatment Plant Resilience for Climate Change

Anacortes, Washington, has rebuilt its water treatment plant to address climate change. The renovation included increasing capacity and implementing strategies to mitigate risks associated with flooding, saltwater intrusion, and sedimentation. By collaborating with nonprofit organizations and utilizing EPA tools, the city has improved the facility’s resilience and preparedness for future climate impacts.

The city of Anacortes, Washington, recognized the vulnerability of its water treatment plant, which serves 56,000 residents and is situated along the Skagit River. In 2003, it was determined that the facility needed an upgrade from a capacity of 21.4 million gallons per day (mgd) to 31.5 mgd. Although moving the facility out of the floodplain was considered in 2008, the cost proved prohibitive, leading officials to opt for a rebuild at the existing site while implementing strategies to address climate risks.

To assess the plant’s vulnerabilities, Anacortes authorities collaborated with nonprofit organizations to identify the best available climate science and its implications on plant siting. Key climate risks factored into their assessment included the anticipated frequency and intensity of storms, potential saltwater intrusion, and escalating sedimentation levels. Projections for the Skagit River through the 2080s indicated an expansion of the 100-year floodplain and an estimated 350% increase in peak winter sediment load, alongside the expected upstream movement of the saltwater wedge due to sea level rise.

When designing and constructing the new facility, officials employed numerous strategies to mitigate the heightened risk of flooding. These included minimizing penetration beneath the existing 100-year flood elevation, elevating critical electrical equipment, utilizing waterproofing techniques below a 40-foot elevation, and constructing ring dikes for flood protection. The rebuilding project carries a budget of $56 million, enhancing the facility’s capacity to meet increasing service demands while adapting to projected climate changes.

Officials utilized various Environmental Protection Agency (EPA) tools to support the project’s success. The EPA Coastal Inundation Toolkit aids utilities in understanding facility vulnerabilities by modeling various scenarios of sea level rise and storm surges. Additionally, the EPA’s Creating Resilient Water Utilities Adaptation Strategies Guide provides low-cost adaptation strategies for integration within design plans, while the Climate Resilience Evaluation and Awareness Tool (CREAT) supports traditional risk-based assessments necessary for identifying further research gaps.

Similar cases to Anacortes’ experience include Manchester-by-the-Sea, Massachusetts, which assessed climate vulnerability in relations to water utilities, and Iowa City, which opted to close a vulnerable wastewater facility due to prohibitive costs. Furthermore, Washington D.C. is employing green infrastructure measures to mitigate flooding risks and manage stormwater effectively.

The city of Anacortes has successfully undertaken a comprehensive approach to enhance its water treatment facility’s resilience against the impacts of climate change. By integrating modern climate science into the design and construction processes, Anacortes aims to safeguard its water supply against future threats. Utilizing available EPA resources has further strengthened the project’s effectiveness, representing a proactive model for communities facing similar environmental challenges.

Original Source: www.epa.gov