Pipe diameter, condition, depth, length, new pipe diameter, soil conditions, and service connections dictate whether pipe bursting is appropriate for rehabilitating a failed line. Photos: Vermeer Corp.
More departments are requiring contractors to bid rehab and new infrastructure projects based on using trenchless methods.
Slip-lining with fold-and-form pipe? Burst, ram, or drill? If you don't have the time or resources to seriously investigate the various methods, consider asking a trusted civil engineering firm to provide an overview. If a particular method seems feasible, suppliers of the appropriate technology will provide more detailed information.
Another resource is the EPA's Capacity, Management, Operations, and Maintenance (CMOM) program, which provides a framework for assessing pipe condition. Video inspection records are invaluable in selecting trenchless alternatives. After assessing system condition and long-term maintenance needs, some departments realize that doing the work in-house ensures access to technology not readily available in their service area, allows for a more flexible operation, and gives them more control over scheduling.
Whatever the motivation, say managers who've made the investment, the decision to purchase should always be based on a hard look at economics and equipment use.
Columbia, S.C., for example, bought several horizontal directional drills to handle smaller jobs and emergencies while continuing to contract for larger projects. The city of Mesquite, Texas, bought a static, 30-ton pipe-bursting system four years ago after calculating the return on investment.
“We've installed more than 10,000 feet of sewer pipe. Our intent is to purchase a larger, 100-ton system to increase our capability, and to start taking on some water-system work,” says Wastewater Superintendent Andy Chennault. “The system paid for itself on the first three jobs.”
— Moore is a technical writer for Two Rivers Marketing, Des Moines, Iowa.