Getting Ahead of a Pipeline Failure: Proactive Condition Assessment and Rehabilitation for a 48-Inch PCCP Wastewater Force Main in West Palm Beach

The City of West Palm Beach, Florida, public utilities department (City) provides water and wastewater services to 120,000 people in West Palm Beach and the Town of Palm Beach (Town). The City’s wastewater collection system includes gravity sewers, force mains, and more than 120 lift stations, with all flows eventually being conveyed to the East Central Regional Water Reclamation Facility through a single force main. The force main is constructed of 42-inch and 48-inch prestressed concrete cylinder pipe (PCCP). The force main was constructed in the mid-1970s under two separate contracts. Price Brothers provided 11,000 feet of 42-inch pipe and 4,800 feet of 48-inch lined cylinder pipe (LCP) for Contract 1 (east of Interstate 95); Interpace manufactured the remaining 13,600 feet of 48-inch embedded cylinder pipe (ECP) for Contract 2 (west of I-95). The history of prestressing wire failures for pipe manufactured by Interpace is well documented. Although the force main has provided nearly 40 years of continuous service, the City recognized the vulnerability of their conveyance system with no redundant pipeline in place. Because the force main passes through the City’s drinking water catchment area, the devastating impacts on public health if a pipe failure and sewage spill occurred made it clear that proactive management of this critical asset was needed. The City engaged Jacobs and Pure Technologies to work together to perform a condition assessment of the entire force main and then develop a rehabilitation plan to address any issues. A condition assessment investigation plan was developed for using Pure’s in-pipe sensing devices to detect leaks, gas pockets, and broken prestressing wires. No leaks were detected, and a limited number of gas pockets were identified. Of greatest concern, however, was the significant number of individual pipe segments (169 total or 23%) of the Interpace 48-inch pipe that had broken wire wrap distress, ranging from 5 to 100 broken wire wraps in a segment. By comparison, few segments of the Price Brothers pipe were found to have broken wire wraps. Based on the degree of wire distress in the 48-inch Interpace pipe segments, the City elected to move quickly to evaluate alternatives for rehabilitation; select a solution; and proceed with design and construction to ensure reliable service, safeguard the City’s water supply, and protect the local environment. This paper will present the results of the condition assessment; a technical overview of rehabilitation alternatives and the selected approach (using cured-in-place-pipe technology); site-specific constraints for performing the work in a highly developed part of the City, including crossing a high-end golf course; techniques and lessons learned for public communications and stakeholder engagement; and project costs.