For funding reasons at Arizona Public Service (APS), the original $1.3 million Make-Up / Blowdown Hypochlorite Trench Structures project was broken into two phases. The first phase, “Trench #20” started in late 2015 and the second phase, “Trench #2″ started in early 2016. The scope of work included digging two large trenches (315 LF and 140 LF, respectively) that were then compacted. Each trench required outfitting of rebar-reinforced, precast, concrete vaults running the entire distance to house pipes carrying sulfuric acid and water to the main cooling towers. Pipe sizes ranged from 1/2″ to 4” in diameter. Once piping was installed, the entire system was checked for leaks and inspected. The final phase of the project included the forming of cast-in-place concrete lids for the entire system that included steel grating for maintenance access.