The City of Glendale is a west valley Arizona city that has 250,000 residents and is home to the NFL’s Arizona Cardinals and has also hosted numerous Super Bowls in the last 20 years. The City supplies water and wastewater services for its residents, and use its wastewater effluent for a variety of reclaimed purposes.
Arrowhead Wastewater Treatment Plant (WWTP) is one of the City’s facilities that treat up to 5 MGD and discharges and pumps its waste activated sludge (WAS) into a 6-in. pipeline that carries that material to a large trunk main that carries the wastewater three miles to a larger west valley plant. This pipeline was installed 30 years ago when the plant was constructed, and was installed with epoxy lined ductile iron pipe.
Over the past five years, there were a number of leaks and issues found with the pipeline that led to an assessment to be completed by GHD Inc., a global civil engineering firm with a local office in Phoenix. GHD’s team completed an assessment of the pipelines and air valves, as well as some CCTV inspections of selected sections and found that the pipe had wall loss on the crown due to air valves not operating, as well as damage at the joints where corrosion had been taking place due to damaged epoxy from when the joints were pushed together. From this assessment project, the City determined that the pipeline would need to be replaced or rehabilitated.
Glendale hired Achen Gardner Construction and GHD to work together on a Construction Manager at Risk delivery method for the design and construction of the project. Due to the high traffic, business, and residential corridor, the City determined that remove-and-replace or a parallel pipeline was not an option. Review of multiple rehabilitation technologies was conducted, and because of the limited laydown area for materials at trenches, multiple vertical and horizontal bends, and operating pressure of the pipeline, Primus Line was the chosen technology for the rehabilitation of the pipeline.
The project construction was completed between October 2020 and February 2021, which is the season in the valley when temperatures are easier to work with. During the project, the City had to use tanker pump trucks to bypass material from the plant to a discharge manhole four miles from the site. This was a huge effort that was completed successfully for the duration of the project. The pipeline rehabilitation was completed from inside the basement of the lift station, just downstream of the system check valves, to the discharge manhole three miles away.
The rehabilitation of the pipeline required 13 access pits, which resulted in liner installations that were between 750 and 1,400 ft from end to end. The Primus Line material was supplied by Construction Product Marketing (CPM), who also provided on-site technical and fitting installation support. The liner was delivered on three spools, two with 7,000 ft of material, and one with 2,500 ft of material. There was a total of 27 low pressure 6-in. fittings installed on the project, and one medium pressure fitting due to clearance limits at the lift station.
Development of the installation pits was completed by Achen-Gardner Construction, which had some challenges due to adjacent conflicting utilities, and traffic control restrictions. Because the Primus Line is flexible and can navigate bends well, adjusting the location of the access pits during construction did not impact the ability to sliplining the pipe. One of the longest runs of material during the project was a 1,400-ft section of pipe that had four vertical bends and two horizontal bends, which the Primus Line was able to handle without any issues.
The project was completed by a qualified and collaborative team, which resulted in the construction finishing on-time and under budget. Because of the success of the project, the City of Glendale was pleased with its first Primus Line installation for a critical piece of infrastructure in its wastewater system.