Municipality replaces water main without closing major street

Problem: A 2,690-foot run of 8- and 10-inch cast iron water main beneath Kingston, Ontario’s Princess Street required one- and two-step upsize replacement with 12-inch PVC pipe. The run lay in backfill over rock 5 to 8 feet beneath a traffic lane that ran alongside a strip mall, the Ontario Government Building and the Kingston Centre shopping mall.

Solution: Utilities Kingston contracted Gordon Barr Ltd. to replace 2,215 feet of the run using pipe bursting. Entry pits were 30 to 50 feet in length. Machine pits for the HammerHead Trenchless HB125 bursting unit, its operator and a helper inside a trench box were approximately 20 by 8 feet. Designed for use on pipe 6 to 20 inches in diameter, the HB125 pulling machine uses heat-treated alloy pull rod with API-style joints that handle the machine’s 113‑ton pulling force capability through long payouts in encrusted pipe and sweeping bends. Brief water interruptions occurred only while switching over to a temporary water supply and while switching back to the new main. Shutdowns were coordinated in advance with businesses, with some performed during nighttime hours. 

Result: Matt Glass, engineering technologist for Utilities Kingston, says the pipe bursting method is ideal for use when water main improvement is the sole purpose of the construction activity. Utilities Kingston completed the project in nine weeks, from groundbreaking to completed restoration, accommodating a high traffic volume with minimal disruption to community activities. 800-331-6653; www.hammerheadtrenchless.com.