2019 Project of the Year New Installation Honorable Mention: PAWC Lake Scranton Finished Water Tunnel
This project involved installation of 5,000 ft of 42-in. steel water main via horizontal directional drilling (HDD) 300 ft beneath the East Mountain Section of the City of Scranton. This new transmission main provides an alternate, reliable means of supplying potable water to the greater Scranton area (over 50,000 homes and businesses) from Pennsylvania American Water’s Scranton Area Water Treatment Plant.
Prior to the completion of this project, the sole means of conveying finished water from the treatment plant to customers was through a one-mile long, 48-in. cast iron pipe located in a hand dug tunnel installed in 1909, which has limited valving and means of access for inspection and repairs.
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Michels Corp. completed the HDD portion of the project by using two 1 million-lb rigs, one staged on either side of the mountain, to complete the 12-in. pilot hole, and to complete the reaming up to the final 54-in. diameter bore hole; 42-in. coated steel pipe was then pulled back in seven 700-ft sections (welding and coating the sections together during pull back).
By using HDD as the means of installation this project limited impact to homes and businesses in the area. Additionally, it allowed eliminated any potential pumping requirements to convey the plant’s finished water over or around the Mountain, and also greatly reduce the length of pipeline required.
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Also, during drilling activities, a large amount of groundwater was encountered, which flowed consistently, at a high rate, from the lower borehole. Although this could have seriously compromised our ability to complete the project, the contractor, working with local officials, landowners, and PAWC’s Scranton Wastewater Division, was able to effectively contain, treat and dispose of the groundwater until the drilling activities and pipe installation was complete.
Project Owner: Pennsylvania-American Water Co. (PAWC)
Engineer: Mott MacDonald
Contractor: Reynolds Construction (general) and Michels Corp. (HDD)
Value of Trenchless Project (US$): $16.5 million
Sharon M. Bueno is managing editor of Trenchless Technology.