Working with CH2M Hill, the Metropolitan Water District of Salt Lake City & Sandy (MWDSLCS) is developing a water supply system to bring up to 70 million gallons a day of water to customers in Draper and Sandy Cities. The Point of the Mountain Aqueduct (POMA) will transport the water to a new treatment plant to ensure supply exists for the growing Salt Lake Valley. The pipeline will also provide redundancy to the MWDSLCS system in the event another portion of the system needs to be taken out of service for repair.
This is not your run-of-the-mill transmission pipe. The smallest portions of the steel pipe are 4 feet in diameter. The largest tower 7 feet in height. The pipe is designed as an engineered system, with elbows and other joints to optimize the system according to terrain and other system needs. The project is manufactured to strict industry standards, using the C200 specification of the American Water Works Association (AWWA). To minimize the number of joints, Northwest Pipe Company’s facility produce each spiral weld steel segment in lengths up to to 50 feet. Fewer joints means less cost and time is spent installing the pipeline. It also means less inconvenience to local residents. Joints were assembled utilizing the weld-after backfill method and girth welds were coated with heat shrinkable sleeves per the AWWA C216 standard. In the case of the POMA project, most joints manufactured as lap-welded bell and spigot ends. ISO-9001 quality policies at Northwest Pipe ensure the entire project is carried out according to customer requirements. This internationally-accepted quality system is a more thorough and extensive process than other pipe manufacturers incorporate. Customers notice the difference in quality and communications throughout the manufacturing process.
The pipeline features the proprietary Pritec® polyolefin coating developed by ShawCor Pipe Protection LLC that is growing in popularity in the water industry. At its ISO-9001-certified facility in Adelanto, California, Northwest Pipe Company employees work with on-site ShawCor personnel to supply the pipeline market with a durable alternative to other dielectric coating systems. Using a state of the art technique, AWWA C200 pipe is blast-cleaned with an abrasive material to prepare the steel surface for the coating application. Then, using a side-extrusion process, molten Pritec is applied to the spiral weld pipe according to AWWA standard C215. This step actually includes 2 layers: a butyl rubber undercoat that is immediately covered with a high density polyolefin.
No rock shield layer is needed because the two materials seamlessly bond into a durable, damage resistant coating. Many owners and engineers favor the material over other dielectric alternatives because of its durability and performance on the job site.