The Bristol County Water Authority (BCWA) provides water to approximately 50,000 customers in the Towns of Bristol, Barrington, and Warren, Rhode Island. The BCWA is a wholesale customer of the Providence Water Supply Board (PWSB). As such, BCWA receives 100% of its supply from the PWSB through a conduit called the East Bay Pipeline. In April of 2019, an alert was triggered resulting from a differential in two BCWA venturi meters located on either side of the Providence River. The differential in flow readings indicated that the East Bay Pipeline had sprung a major leak, discharging approximately 400,000 gallons-per-day. At this time, BCWA hired BETA to manage emergency response actions relating to the investigation and repair of the leak in this transmission main. Initial investigation and repair efforts revealed two small holes on pipe welds approximately 1,800-feet into the pipeline and 180-feet beneath the Providence River.
Once the break was pinpointed, BCWA contracted with BETA to design the repair of the pipeline. BETA completed the design of the repair and prepared construction documents in one month. Multiple sliplining technologies and materials were evaluated based on their installation requirements, hydraulic capacity, and costs. BETA ultimately recommended sliplining the existing water main with an 18-inch DR 18 Fusible PVC pipe. The Fusible PVC pipe solution provided for the best possible water system hydraulics and met the significant pressure requirements due to the depth of the existing water main beneath the river.
Due to the critical nature of this project, the pipe was preordered by the Owner to avoid any lead time issues which could have prevented the pipe from being installed in the scheduled timeframe. Once the Contractor mobilized, BCWA activated a 16-inch interconnection with the City of East Providence and the repair commenced. Once shutdown, the entirety of the pipeline was CCTV inspected to ensure that there were no other issues that would be prohibitive to the sliplining itself.
Pipe staging and fusing of the PVC pipe segments occurred in the golf course on the east side of the Providence River. The PVC was fused into 450-foot lengths and air pressure tested to 5 psi to confirm that there were no issues with the fused joints. A 90-foot “prover” piece was pulled through the host pipe to gauge the integrity of the PVC once pulled through the existing main. Once complete pulling of the prover segment, the sliplining commenced. The sliplining was completed over the course of three days and consisted of pulling each 450-foot section and then ballasting the section from the tail end. Once complete with the pull, the annular space was grouted on each end to stabilize the PVC and seal off the joints. The PVC pipe transitioned to ductile iron and permanent connections were made to the steel main. The main was flushed, disinfected, and returned to service in November 2019.