Sliplining the Solution for 100-Year-Old Water Main
In June 2022, Spiniello Companies completed 20,000 lf of 6-in. diameter sliplining with fusible PVC pipe for Pennsylvania American Water in Quarryville, Pennsylvania. The existing 10-in. diameter water main is believed to be more than 100 years old and was originally installed to provide water to the locomotives of steam engine trains (the path of the railroad has since become a pedestrian trail).
There were no as-built drawings available from the original construction, so the location of the pipe and later access pits were determined through the use of ground penetrating radar and test pitting.
The existing 10-in. diameter water main ran along a small stream, a tributary of Bowery Run, through wooded areas and farmlands. As the stream has naturally drifted since the original construction, the water main tacked back and forth on either side of the stream for the length of the project, complicating the access plan.
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There were no access roads or water main markers so test pits were dug by hand to minimize disruption to the adjoining properties. After locating the water main, paths through the forest were cleared to excavate access holes. The majority of the jobsite was active public/private hunting land so close coordination with the land owners and the wearing of safety vests were extra important.
After access pits were excavated, the water mains were “tagged” to prepare for cleaning, which is pipe-lining slang for running an initial rope through the pipe. Once installed, winch truck cables were run through the pipe attached to cleaning tools including large scrapers which are pulled back and forth to remove existing tuberculation, found to be extremely heavy in the old mains. A jetter truck was also brought in to clean these segments in tandem, increasing the ability to clean longer runs, up to 1,000 lf at a time. Prior to the start of sliplining, the main was televised to determine the location of any existing services.
To avoid the need to bring each winch truck to the access pits, several rolls of cable were used to increase cleaning production to 3,000 LF at a time. Cables would be pulled through the pipe, disconnected from the truck, and attached to the next cable drum to continue pulling through the pipe. The bulk of the job was completed in the winter months to take advantage of the frozen fields and lack of planted crops. The ground cover over the course of the project went from frozen solid to wet, deep mud. Traversing from one location to another was a constant issue.
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The pipe was exposed in the areas it crossed the stream, requiring special environmental permits to be obtained before pipe rehabilitation. A survey for Bog Turtles, the smallest North American turtle and a Critically Endangered species, was conducted halting production on the project for several months.
Once the threat of habitat destruction was determined to not be a risk, Spiniello returned in May 2022 to build two dams across the stream. The first was a stream pump-around using 6-in. diameter pumps to bypass flow to below the worksite. A second pumping site was used to pick up any flows that made their way into the excavation site. The secondary pump discharged 150 ft downstream after flowing through several filtration devices.
The final project step was to install cellular grout in the annular space between the new fusible PVC and the existing main. Access points for grouting were also limited to where a grout pump truck could safely access. Wherever the grout pump was staged, a full-size concrete mixer truck would need access to the pump hopper.
The project was completed successfully in June 2022 renewing water service and improving water quality to the town of Quarryville, Pennsylvania.
Tim Bako is the vice president of corporate strategy at Spiniello Companies.
