Madison adopts monitoring strategy for defective UV-cured sewer liners in backyard easements

Madison adopts monitoring strategy for defective UV-cured sewer liners in backyard easementsRather than immediately rejecting wrinkled sewer liners installed by Visu Sewer, city engineers will observe flow characteristics over the next year to determine if the defects necessitate increased maintenance.

Two sanitary sewer mains lined with UV-cured CIPP display wrinkling and bulging defects, potentially impacting flow.

The city transferred the $33,747.70 value of the work to a new 2025 contract to allow for a prolonged monitoring period while closing the previous contract.

The contractor attributes the defects to the existing clay pipe being slightly smaller than the standard 8-inch diameter.

If accumulation occurs, the city may place the lines on a high-frequency cleaning schedule and reduce or withhold payment.

The Madison Board of Public Works has approved a contractual adjustment to address defective sanitary sewer liners installed by Visu Sewer, opting for a long-term monitoring strategy rather than immediate remediation due to site constraints. During a December 17 meeting, City Engineering staff presented a change order moving two specific sanitary mains from a completed contract to an active 2025 CIPP UV lining contract. The transfer, valued at $33,747.70, allows the city to close the previous project while retaining leverage over the contractor regarding the quality of the work. According to city staff, the liners in question were installed in backyard easements and exhibit visual defects, including wrinkling and bulging. While these defects do not currently cause immediate backups, engineers are concerned they may trap debris and impact flow characteristics over time. Because the mains are located in backyards rather than under roadways, excavating to cut out and replace the liners is considered logistically difficult and invasive. City Engineering negotiated an arrangement where Visu Sewer will monitor and televise the mains every three months at no cost to the city. If the defects are found to inhibit flow or cause accumulation, the city plans to intervene with its own operations crews to clean the mains. In that scenario, the infrastructure would be placed on a more frequent operations and maintenance (O&M) schedule, and the city would likely withhold payment or negotiate a reduced rate based on the increased maintenance burden. The contractor has theorized that the defects occurred because the existing clay pipes from the 1960s were slightly smaller than the standard 8-inch diameter—potentially 7.5 inches—causing the 8-inch designed liner to fold upon itself during curing. City staff noted that verifying pipe dimensions is the contractor's responsibility and viewed the explanation with caution. The Board approved the transfer, allowing the city to hold the funds in contingency while the performance of the liners is verified over the coming year.