As small towns and cities across the country are looking at losses in revenue due to COVID-19, many still cannot postpone major infrastructure needs. With the continuing uncertainty in the economy, communities need more cost-effective options for their critical infrastructure projects. Small problems like root infiltration, soil movement, water pressure changes or just plain old age can damage water and sewer pipes, sometimes causing pipes to collapse, crack, or clog. This leads to major leaks, backups, and sinkholes.
The City of Mahnomen, in northern Minnesota, had many of these major problems arise. After multiple backups caused by so called “disposable” wipes catching on offset joints, mineral deposits, and dilapidated manhole structures, the City was forced to institute a monitoring program as well as a regularly scheduled pipe cleaning program. Both these items increased staff time and maintenance costs for the community.
Faced with many more expensive short-term repairs in the future, the City of Mahnomen contracted with Widseth to complete a comprehensive evaluation of their water and wastewater systems. We reviewed and recommended multiple options for their short- and long-term maintenance and improvement needs. Review of sanitary sewer video showed that the backups were due to multiple issues with the pipes, which were broken, missing, egg shaped, partially blocked, or deteriorated. Virtually all sewers were also experiencing infiltration that caused even more load on the water treatment system.
But what options are there to reduce the cost to communities for these big projects?
We found that many of the lines did not need total replacement but could instead be repaired with Cured in Place Pipe, or CIPP, a jointless pipe-within-a-pipe solution that doesn’t require retrenching or tearing up whole streets for replacement. This less invasive method lines cracked and damaged pipes with a seamless cloth tube. Each tube is custom cut for the exact length needed, then infused with a resin that hardens the tube after it is applied to the pipe.
Mahnomen Plan showing areas where CIPP will be used and other water and sanitary sewer will need replacement.
Mahnomen’s $6.5 million USDA-funded rehabilitation project started last September by repairing critical watermain needs before winter. The project continued this year with replacing lines in some areas that required full excavation. Later this fall and into next year, the CIPP rehabilitation is scheduled to take place. The first step in CIPP installation will be clearing and cleaning the sanitary sewer lines of roots, deposits, and debris. Then lines are checked by remote camera to assure they are cleared and ready for the CIPP installation. Next, the CIPP liners are pulled into the pipes and are cured using steam or hot water to harden them in place.
CIPP installation process from the street level.
Rehabilitation of the watermain, wastewater, and storm sewer, including the CIPP lining, is scheduled for completion in the fall of 2021, with final completion scheduled for June 2022.
Trenching for water and sewer pipes is more expensive and inconvenient than CIPP repair, but sometimes needed as part of the overall water and waste water systems repairs.
The combination of CIPP liners with full pipe replacement provides a cost effective and durable solution that should keep the sanitary sewer mains of Mahnomen clear of leaks, infiltration and other deficiencies for many decades into the future. Not only will the sewer mains be in great shape for many years, but residents should see a reduction in costly maintenance repairs, energy costs, and sewer backups, and overall increased system reliability.