Wastewater Treatment Plants (WWTPs) are typically located at low points in watersheds or coastal and river areas. Many WWTPs have recently undertaken studies to assess vulnerability to more extreme flooding events due to climate change and sea level rise. Powerful storms have inundated WWTPs with storm surge, causing hundreds of millions of gallons of untreated sewage to spill into neighboring waterways. In response, WWTPs across the U.S. have developed resilience plans and increased infrastructure fortification against floods and storm surge.
Sewer Authority Mid-Coastside (SAM) is a Joint Power Authority formed in 1976 and provides secondary wastewater treatment to an average flow of 2.0 million gallons per day. SAM performed an evaluation of its WWTP and Pump Stations reliability against electromechanical failure, natural hazards, malevolent threats, and failure of critical dependencies.
The scope of the evaluation study included a) external hazards which pose a threat to the proper functioning of the WWTP and Pump Stations and b) Electromechanical equipment failure event due to general equipment failure, age and/or lack of redundancy. The selected methodology assesses risks associated with hazards to, or failure of, critical infrastructure, and identifies, quantifies, and relates a utility’s level of risk and resilience. In this assessment, risk and resilience, respectively, refer to the ability of an asset to withstand and/or return to service after an interruption.
Critical assets were identified and assessed for current conditions and expected performance against their estimated remaining useful life. Hazards and resulting vulnerabilities to these assets were then ranked in terms of how their respective occurrence or failure could impact the functionality of the WWTP and Pump Stations. Each hazard’s consequence was ranked against the expected likelihood of occurrence, or risk. Recommendations were made to improve operator and/or public safety were given a higher level of priority