Underground Solutions Project Profile
Situated in the pristine rolling hills of Berks County, Pennsylvania, the Western Berks Water Authority (WBWA) operates its municipal drinking water facility with a profound sense of duty to protect the environment and serve its customer base. When the authority embarked on a project to provide water to the County’s key agricultural and public service entities, it knew the design and construction of a new transmission line would need to embody the same community and environmental ethics.
WBWA contracted with the SSM Group, Inc. (SSM) to design the transmission line that had to overcome a variety of obstacles, including crossing the Tulpehocken Creek (a waterway protected by the Pennsylvania Scenic Rivers Act), wetlands, and a historic canal. The transmission line, operating at 170-190 psi static working pressure, is in close proximity to two cathodically protected gas lines. Due to the increased costs and long-term risks associated with cathodically protecting the line in an environmentally sensitive area, SSM decided to deviate from the authority’s past practice of installing ductile iron (DI) pipe. Recognizing that a gasket-free, leak-free thermoplastic pipe would best serve the community, SSM and WBWA selected 16″ DR14 Fusible PVC® pipe to be installed for the entire length of the 6,390 LF transmission line.
WBWA Executive Director Chip Bilger stated: “Given the geography we were crossing and the pressures at which we were operating, we saw significant value in having a transmission line serving our community that would not corrode or leak – ever. Underground Solutions’ customer-focused business model and proven track record made Fusible PVC® pipe our clear choice.”
Fusible PVC®’s Hydrostatic Design Basis (4,000 psi) allowed for a 16″ DR14 (305 psi) pipe to be utilized for the HDD and open-cut sections. A lower pressure rated 20″ HDPE DR7.3 (255 psi) would have been required to meet the same cross-sectional flow area provided by the Fusible PVC® pipe. The larger outside diameter of the competitive HDPE pipe would have added significant material, installation, and fittings costs to the overall project. An average of the top four bid submissions showed that the 20″ DR7.3 HDPE pipe would have added 38% more in costs for the open-cut section alone. The 20″ DR7.3 pipe was not considered for the HDD operations because of the increased costs associated with installing the larger diameter pipe (larger borehole).
The 5,490 LF of open-cut installation took just over three weeks to complete. The difficult 900 LF HDD required a specialized 21″ rock reamer for the final ream pass. The transmission line was completed and pressure tested at 255 psi for two hours in March 2012.