For at least 30 years, U.S. water and sewer utilities have been able to slipline water, sewer, and storm pipelines with a trenchless construction method that has virtually no impact on capacity.
In Swagelining, an HDPE pipe is pulled through a dye. This stretches the pipe, reducing its outside diameter. When the tension is released, the liner pipe relaxes and assumes its original diameter. The liner and host pipes are such a tight fit, there’s no annular space to fill with grout or other material, as is often the case with conventional sliplining.
Eliminating a step usually saves time, and thus, money, on construction. So why isn’t Swagelining, which is available nationwide via Murphy Pipeline Contractors Inc.’s Allied States Cooperative contract for water, sewer, and storm mains 2 through 60 inches in diameter, specified more often?
One word: budget. The process is more complicated than conventional sliplining, requiring additional and larger equipment.
But there are instances when it’s the only tool for the job. The ideal circumstances involve:
- Pressurized pipeline
- A straight run of no more than 2,000 feet
- A requirement to maintain the pipeline’s hydraulic capacity
- A requirement for a partially to fully structural solution.
For the two projects discussed, Fort Collins Utilities rejected cured-in-place pipe (CIPP) and applied coatings. With the passage of time, they may become feasible options for the remaining 17,600 feet of Poudre Canyon Waterline.
“The technology is changing so fast, they’ll need to revisit the materials and methodologies on the market for pressure pipe rehabilitation before making a decision for rehabilitating this very challenging waterline,” says Ken Matthews, PE, the Stantec consultant who advised the agency on its Swagelining projects and has since joined Merrick & Company.