Concrete Solutions: Repurposing Existing C76 Gravity Pipe to Save $1M and Costly Permitting Delays

The water surface elevation (WSEL) of the existing Highline Canal is approximately 20 ft above the WSEL of the existing San Tan Canal (STC), where the reclaimed water from the City of Mesa would be discharged, necessitating the design and construction of a low-head gravity pipeline of varying diameters. The alignment of the gravity pipeline crosses a spur of the Union Pacific Railroad (UPRR) and Arizona State Highway 87. Near this crossing is a 350-ft segment of abandoned 24-in. C-76 concrete gravity pipeline housed in a steel casing and hydraulic modeling suggested that incorporating this abandoned pipeline into the alignment of the proposed low-head gravity pipeline was feasible. Unfortunately, the existing pipe condition is structurally inadequate. Repurpose the existing C-76 gravity pipeline and manholes with a Sprayed-in-Place pipe (SIPP) liner saved months, or years, of schedule delays, and upwards of a million dollars in permitting and construction of a new trenchless crossing.