Fusible PVC® Pipe Used for Record Directional Drill in Delta, Utah

The geography of Utah is widely renowned for its sprawling mountain ranges and remote desert beauty. However, its landscape is also dotted with many lakes and wetlands, all which contribute greatly to the state's massive and diverse ecosystem. While the Great Salt Lake stands strong as the largest body of water west of the Mississippi River, there are hundreds of natural and manmade lakes in Utah. The unique, glacial-formed topography is well-suited for manmade reservoirs in the valley floors between mountain ranges. One such reservoir is the 700-acre Gunnison Bend Reservoir, located about 120 miles south of Salt Lake City. The reservoir acts as the eastern border of the City of Delta, and was formed by damming the Sevier River for irrigation. Constructed on one of the reservoir's far reaching peninsulas is the Sherwood Shores Subdivision, an elegant lakeside property development. In order to provide culinary water meeting EPA requirements, a line needed to be installed from the City of Delta to Sherwood Shores.

Sunrise Engineering of Fillmore, UT was hired to find a cost-effective way to deliver water to the peninsula using a plan that would also provide the least amount of disruption to the local residents. Sunrise determined that, rather than direct-bury a new pipeline around the lake, the line should be installed under it via horizontal directional drill (HDD). A large open-cut installation along the shoreline would be time-intensive, costly, and intrusive. The engineers believed the HDD approach would mitigate most, if not all, of those concerns. Nevertheless, an HDD installation of 2,730 LF of plastic pipe is a challenging undertaking, one that had never been done before in the state of Utah.

To promote competition, Sunrise bid the project with alternatives for HDPE and Fusible PVC® pipe. The desired outcome was to maximize flow at the lowest cost. Therefore, the design allowed for various options: 12-inch DR18 Fusible C-900® pipe with an inner diameter (ID) of 11.7 inches and a 235 psi pressure class (PC); 10-inch DR18 Fusible C-900® (9.9-inch ID, 235 psi PC); 10-inch DR11 HDPE (9.0-inch ID, 160 psi PC); and 12-inch DR11 HDPE (10.7-inch ID, 160 psi PC). Compared to HDPE, PVC pipe exhibits more than twice the tensile strength which provides a greater safe pull force resulting in much lower risk. For these benefits alone, and its cost compared to HDPE, the City of Delta elected to install 12-inch Fusible C-900® pipe. Also, with over 25 documented pulls greater than 2,500 LF, Fusible PVC® pipe has a successful history on similar installations.

The low bidder, Barton Excavating, selected HDD Specialists for the bore. Drilling began in the spring of 2013 and was completed by summer. Connections and pressure testing were successfully completed shortly thereafter by Barton Excavating. Robert Worley, project manager for Sunrise Engineering, said, "With the technology available today in drilling equipment and fusible pipe, installing the pipe under the reservoir proved to be a great long-term solution for Delta City."

Darren Knight of HDD Specialists said, "This long directional drill had varying geotechnical conditions - it was reassuring to know that we had a pipe material which could handle both the soil conditions and provide additional pull force if we needed it."

Pipeline Details and Project Summary
Project: Delta City Water Line Extension to Sherwood Shores Water Company
Owner: City of Delta, UT
Engineer: Sunrise Engineering, Fillmore, UT
General Contractor: Barton Excavating, Ephraim, UT
Directional Drill Contractor: HDD Specialists, Fort Collins, CO
Directional Drill Length: 2,730 LF of 12" DR18 Fusible C-900®
UGSI Contact: Patrick Laidlaw, P.E. (801) 699-2804 plaidlaw@undergroundsolutions.com

Pipe inserted into the bore pit

Pipe strung out

Gunnison Bend Reservoir used for recreational purposes

Abnormally wet summer in Utah made protection from the elements necessary during the fusion process

Directional Drill Rig