Water Main CIPP

The City of Ray, North Dakota, had replaced the highest priority cast iron water mains from 2012 to 2014 to address poor chlorine residuals, rust-colored water, and dependability. Though the chlorine residuals improved, rust-colored water still occasionally occurred, triggered from tuberculation in the remaining cast iron mains. The city consulted with Interstate Engineering to devise a plan to improve the city’s water system while minimizing disruptions to the public.

Interstate Engineering became aware of a water main cured-in-place pipe (CIPP) technology. Once the concept was brought to the city, Interstate Engineering was tasked with determining if it was practical in addressing the city’s problem. Once feasibility was established, Interstate Engineering further researched which trenchless method was most appropriate for the project. Because water main CIPP renovation is a relatively new procedure, representatives from Interstate Engineering and the City of Ray traveled to Seattle to observe a CIPP water main renovation project during construction.

CIPP offers many advantages, specifically when the water main is the only utility in need of repair. When a water main is located in a paved and congested utility corridor with multiple service connections, CIPP requires less excavation and restoration than traditional open-cut methods. It also has minimal impact on adjacent utilities. The design life of a fully structural Class IV liner is 50 years, meeting the ASTM standards.

Interstate Engineering presented a recommendation the City of Ray to proceed with the project utilizing CIPP technology. The city proceeded with the renovation of over 7,100 linear feet of water mains using CIPP. The project included 110 water service connections, each one being reconnected internally using robotic equipment. The water service connection process left the street surface undisturbed, a distinct difference to a pipe bursting technology where the main needs to be dug to reconnect each service. Interstate Engineering assisted the City of Ray in securing Drinking Water State Revolving Fund loans for the project. Sixty percent of the water loans were loan forgiveness (grant funds).

The water main CIPP renovation was completed within budget and schedule with minimal public inconvenience. The city saw an estimated savings of between 20% and 25% in comparison to the estimated cost of an open-cut water main replacement project for the community.