Multi-year infiltration leak stopped in one hour with Prime Flex 920
One hour and 30 litres of a hydrophobic polyurethane grout is what it took to stop a gushing water infiltration into Kingston, Ontario’s sanitary sewer system. Kingston sits at the mouth of the Cataraqui River where the St. Lawrence River flows out of Lake Ontario. Much of the city sits on limestone bedrock that must be channeled to install water, sewer and service lines. The leaking manhole was located on a sanitary sewer mainline that crosses a swamp, and the manhole was acting as a drain. How major was the problem? The city had a leak in a manhole of a sanitary sewer line where a 25-cm pipe came into the manhole at the bottom of the bench. Water was flowing around a pipe union at the rate of about 23 litres per minute, according to estimates from Utilities Kingston. That translates into some 12 million litres of infiltration a year, and the leak was active for seven or eight years.
Chemical grouting stops infiltration
“Since chemical grouting is still relatively new in Canada, the client was a bit reluctant to try something they were not familiar with,” says Jim Hill of strataWORKS Canada Ltd., a public works distributor of infrastructure repair solutions. “So we hired a contractor who had been to Prime Resins for training. There was no risk; I knew it would work.” Prime Resins is an Atlanta-based manufacturer of infrastructure repair chemicals, mainly polyurethanes, epoxies, acrylates and polyureas for leak sealing, soil stabilization, slab lifting, lining and structural repair.
Dynamite Contractors injected the resin in the manhole about three metres below grade. The work entailed drilling a series of holes and injecting Prime Resins’ Prime Flex 920 and Kick Fast Kat activator into the holes. Prime Flex 920 is a single-component, water-activated polyurethane resin that is ideal for infiltration problems like this. The job was finished in a morning and cost $4,000.
“The Kingston officials were in disbelief at the results. They had tried several other options before that hadn’t worked, so they did not expect this to succeed,” says Hill.
Infiltration water was mixing with sewage, so additional handling and operation costs included pumping the volume of extra water to the treatment facility, extracting clear water from the sewage and then discharging the water. The cost recovery of the project can be measured in weeks.
Kingston is now conducting field inspections and compiling a prioritized list of manhole and pipe repairs. Similar problems will be fixed using the same grouting method as the first manhole.
“Chemical grouting is definitely a method I would recommend to other municipalities dealing with infiltration challenges,” says Hill. “The awareness and use of chemical grouts for infrastructure repair is still small here in Canada but growing. We always show the municipal public works departments we work with how they can make small, highly effective repairs on their own with easy, ‘crew ready’ cartridges. These make it easy to use and don’t require the investment in pumping equipment.”
While in-house municipal grout crews are becoming more common across the U.S., Hill thinks it could be some time before many Canadian cities are in the same position. “The mandate to focus on asset management and cost benefit analysis is pushing public works departments to implement better strategies, but operating budget constraints too often force managers who want to adopt proactive practices to function in a reactive capacity.”
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