Ocean Wastewater Outfall Infrastructure Needs Love Too: Strategies to Perform a Successful Assessment Program

CH2M HILL has recently performed several successful condition assessments of critical ocean wastewater outfall structures. Assessing the structural condition and hydraulic performance of ocean wastewater outfalls represents some of the greatest challenges to agencies controlling publicly owned infrastructure. These structures are extraordinarily difficult to access, require a carefully executed inspection plan, and often require advanced technologies to gather the data needed to complete a successful assessment. In many cases these condition assessments represent the first attempt to inspect the existing infrastructure since their original installation and, as such, will form the baseline for future inspections. This paper presents an overview of strategies that were implemented (or will be implemented) for comprehensive assessments at four outfall locations. These locations and strategies are briefly summarized as follows: Anchorage, AK—Inspection and assessment of the Anchorage Water and Wastewater Utility (AWWU) 84-120 in. Asplund wastewater treatment plant (WWTF) 900 ft outfall and control structure existing in an area with tidal fluctuations of up to 35 ft. Honolulu, HI—Preinspection and assessment of the City and County of Honolulu (CCH) Honouliuli WWTP Barber's Point outfall system representing nearly 19,700 ft of 84 in. RCP (both land and ocean portions). Port Townsend, WA—Inspection and assessment of 840 ft of submerged 18-20 in. outfall and diffuser structure performed in two stages. Ponce, Puerto Rico—Internal and external inspection and rehabilitation of the PRASA Ponce Regional WWTP outfall structure (21,000 ft of 48 in. pipeline). Each project required overcoming unique challenges and conditions that can be applied to a broad range of ocean outfalls. This paper reviews the work plans developed and implemented to leverage the right people, equipment, technologies, and science. The goal of each assessment was to create a sustainable road map for this wastewater infrastructure.