Client: Town of Bedford
With its sewage treatment plant near capacity, the last thing the Town of Bedford, Nova Scotia, needed was unnecessary sewage treatment. But it was getting just that because of groundwater leakage into its sewer system through the seal between the rings of the town's concrete manholes.
The biggest problem was a 22 ft. (7 m) deep manhole located under a busy street in an industrial park, according to Daryl Sheehy, the town's Municipal Services Inspector. Faced with an estimate of $12,000 for a conventional repair requiring excavation and closing the road for the duration of the work, Bedford's engineering department went looking for a better way.
They called PERMA-DRY who suggested their own crack repair process, carried out using PERMA-DRY's THERMO-Jet technology and PERMA-SEAL, a specially-formulated repair material that is pressure-injected to ensure penetration through the entire wall, from the inside out. PERMA-SEAL fills the joint and all capillary cracks, thermally fusing concrete together.
The town commissioned the repair of one manhole as an experiment in November, 1994 and found the leakage of ground water stopped immediately. By sending PERMA-DRY's men and equipment into manholes to repair them from the inside, Bedford avoided costly excavation work and traffic burdens. Eliminating groundwater intrusion eliminates the load on pumps, thereby extending their life expectancy, conserving electricity, and increasing efficiency for household services.
"The cost for PERMA-DRY treatment was about 10% of the cost for a deep manhole and about 30% for conventional manholes 10 ft. (3 m.) deep," Sheehy says. Since then, Bedford had ordered work on several more manholes.