- ENGINEERING INFO
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Big Horn Regional Joint Powers Board (BHRJPB) manages water transmission lines in north central Wyoming and is the chief water purveyor in an 800 square mile area. To date BHRJPB has installed over 100 miles of water transmission lines ranging in size from 12-inch to 24-inch. These transmission lines feed another 400 miles of smaller diameter distribution piping to convey water to surrounding rural water communities. Due to the corrosive nature of the soils in the region, most of the pipe installed throughout the system is plastic. While PVC is the most predominant pipe material in the system, HDPE pipe, FRP pipe (in high temperature applications), and steel pipe (in high pressure applications) have also been used.
Recently, BHRJPB embarked on the Well #2 Connection project, requiring construction of 11 miles of new 12-inch and 18-inch diameter pipe. When DOWL consulting engineers of Sheridan, Wyoming completed the soils report for the project, the most important finding was that soils in many parts of the pipeline alignment were comprised of very expansive clay. In some areas, soil movement was anticipated to be up to 18 inches. While the bentonite clay found in the soils is useful as an effective drilling mud lubricant in horizontal directional drilling, it presents unique challenges when designing a water transmission pipeline.
Given the utility’s experience with a wide range of pipe materials, and to address the challenges of this specific project, both BHRJPB and DOWL concluded that PVC pipe was the best choice for the project.
Over four miles of the 12-inch pipeline traversed sections with expansive soils. There was significant concern that unrestrained bell-and-spigot PVC pipe could pull apart in these sections from the anticipated soil expansion. Due to corrosive soils, there was also a desire to minimize metallic hardware on the pipeline. Given the need for a restrained pipe system with minimal hardware, the pipe material specifications limited contractors to using restrained joint PVC or Fusible PVC® pipe. Four out of six bidding contractors selected Fusible PVC® pipe as the basis for their bids. The successful low bid contractor, Mountain View Building of Sheridan Wyoming, selected Fusible PVC® pipe for the open-cut sections based on cost and ability to pull fused pipe strings over hilly terrain into an open trench. On the directional drill sections, Fusible PVC® pipe was selected for its smaller OD at the joints and higher rated pull force.
Construction commenced in fall 2014, and final pressure testing at 235 psi was completed in late February 2015.
Most of the construction was completed during the cold Wyoming winter months. The primary installation approach was to fuse and install 1,000-foot pipe strings.
Jason Spielman, P.E, owner of Mountain View Building, commented: “This was the third project we have completed with Fusible PVC® pipe. The terrain was hilly and the soils ranged from very hard when dry to a slippery clay mess after rain events. Through all of this weather, including sub-zero temperatures, we were able to pull and install long, fused pipe strings very efficiently.”
DOWL Project Manager, Dayton Alsaker, P.E., added: “The Fusible PVC® pipe on this project was installed in a challenging location during cold weather without incident. Considering the multitude of design challenges, including corrosive and expansive soils, system hydraulic requirements, the need to minimize leaks, and a tight budget, Fusible PVC® pipe was our preferred alternative.”
John Joyce, Director of BHRJPB, stated: “We were pleased to find a pipe product that met all of our criteria for crossing the expansive soils in the Well #2 Connection Project. Ambient temperatures during construction ranged from over 90 degrees during fusing operations to negative 10 degrees during installation. The fused pipe went in smoothly and passed pressure testing on the first attempt every time, with no leaks. We are looking forward to adding our new artesian well to the system.”
|Pipeline Details and Project Summary|
|Project:||Big Horn Regional Joint Powers Board Well #2 Connection Project|
|Location:||Big Horn County, Wyoming|
|Length/Size:||Direct Bury: 22,060 LF of 12” DR18|
|Length/Size:||Directional Drill: 500 LF of 12” DR18 and 2,100 LF of 18” DR18|
|Owner:||Big Horn Regional Joint Powers Board|
|Contractor:||Mountain View Building (General Contractor)|
|Contractor:||MCM General Contractors (HDD Subcontractor)|