WSU Installs Inliner® CIPP Along Busy Mountain Highway

As the only paved access route to scenic Mount Lemmon near Tuscon, Ariz., the Catalina Highway sees more than 1 million travelers per year. Mount Lemmon is a popular destination for bicycling, motorcycling and hiking enthusiasts, and is also home to the southernmost ski resort in the U.S.

When the Pima County (AZ) Department of Transportation discovered large cracks forming in the pavement directly above stormwater culverts that transversed the highway, they assumed that the stormwater pipes themselves were in a similar state of disrepair.

Western Slope Utilities, an Inliner Technologies licensee, in a unique partnership with its parent companies Granite Construction and Kenny Construction, was tapped to install Inliner® Cured-in-Place Pipe in 31 storm culverts ranging from 24”-48” in diameter.

Granite, a traditional heavy construction company with roots in road construction, material mining and production that had a longstanding relationship with Pima County DOT, was charged with the overall administration and traffic control.

The pipes were full of silt, rocks and other environmental debris, so none of the parties involved with this project were certain of the ultimate conditions of the pipes being renewed.

The work was performed in areas with highly sensitive environmental considerations – including 14 species of owl, two of which are legally protected. Work was limited to 6 a.m.-6 p.m. so as to not disturb them.

Because the work was performed along this two-lane winding mountain highway with no access to water or wastewater discharge for the cure water, the CIPP tubes were installed with air pressure then cured with steam, then the small amount of condensate was hauled offsite for disposal. The vehicle and equipment staging areas were very limited, and workers had to wear fall protection equipment for work performed at the downstream ends of the pipes being renewed.

Because Catalina Highway is the only paved access route to Mount Lemmon, precise traffic control sequencing was important to keep the route free for tourist and residential access.

The contract allowed for 126 calendar days, however the WSU-Granite-Kenny team successfully completed the work in 70 days, to the owner's great satisfaction.


Western Slope Utilities oversaw CIPP lining, under its parent company, Granite Construction Company, the prime contractor.