TPI November 2020

Case study: HDPE pipe brings potable water to rural area of US By Plastics Pipe Institute, USA

The necessity of a new potable water pipeline was critical for residents of this rural area because local supply wells were found to have high concentrations of trichloroethylene (TCE), a widely used industrial solvent known to be a human carcinogen. The tests did not, however, pinpoint the source and the decision was made to bring water from three new wells that were outside the contaminated area. The $20mn-plus project involved the wells, water tower, a treatment plant and nearly 10 miles of high-density polyethylene (HDPE) pipe to deliver the fresh water to nearly 450 homes and businesses. The goal for the new pipeline system was to have it be entirely leak-free. “About 10 years ago a developer was building 55 houses and wanted to put in a community water system rather than individual wells for each home,” explained David Linahan, principal engineer of Groundwater & Environmental Services, Inc (GES) in the US. “This needed a permit and the state requires much more testing for a community well versus an individual well. The Pennsylvania Department of Environmental Protection discovered TCE in the groundwater and wanted to find the source of this contamination. In the meantime, that developer had to put in a treatment system so the water could be approved for drinking purposes. The geology in the community is dolomite, very similar to limestone, and it’s a karst geology that makes it very difficult to predict ground water movement

The new system Linahan and his GES team designed would use 52,000ft of the HDPE pipe plus more than 200 valves and 69 fire hydrants, which was able to be on-site within three weeks from the local branches of Core & Main LP, formerly HD Supply Waterworks Ltd. GES was also responsible for the design and overseeing construction of the 900,000 gallon-per- day water treatment plant and the 500,000-gallon capacity water tower. Using the HDPE pipe for the distribution line enabled the system to be installed mostly using horizontal directional drilling (HDD) along Old Philadelphia Pike (PA 340), Newport Road (PA 772), Queen Road, Hatville Road, Field Crest Lane and Harvest Drive, a local township road. According to a recent Utah State University report, HDPE pipe is the most accepted pipe for trenchless applications such as HDD and others. “HDPE pipe is the number one material for trenchless construction,” stated Camille George Rubeiz, PE, F. ASCE, senior director of engineering, municipal and industrial division for the Plastics Pipe Institute, Inc (PPI). “Its high flexibility, tight bending radius, high impact resistance, high ductility and longest fatigue life makes HDPE the preferred material for the major trenchless installation such as sliplining, horizontal directional drilling (HDD), Swagelining™

through the subsurface. That complicated the investigation and the DEP realised they needed to do something to provide the community with safe drinking water. The Department decided to provide a new water supply and distribution system with ground water wells. Early on, the decision was also made that the distribution piping would be all HDPE with the idea of putting it in using horizontal directional drilling.”

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TUBE PRODUCTS INTERNATIONAL November 2020

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