Minimum-disruption repair

Most utilities confronted with repeated service line repairs have adopted the use of trenchless technologies to replace the lines. The process typically involves cutting pavement, excavating to the corporation stop in the main, and extracting or splitting the existing service line with a cable and splitting tool attached to a backhoe. The new service pipe is attached to the end of the cable and pulled into the alignment of the extracted or split old service line from the water meter side of the service.

“Utilities are adopting a variety of strategies depending on pipe material replaced and soil conditions,” says George Malakis, a regional vice president of TT Technologies Inc., an Illinois manufacturer of pneumatic, static, and lateral pipe-bursting systems and other trenchless construction equipment. “An experienced crew in ideal conditions can replace up to four or five service lines in a typical shift.”

While many utilities specify copper (sometimes in “hot soils,” with a sacrificial anode and/or PE cladding) as the replacement material, the complications of corrosion protection, price variability, and jobsite theft created a need for a new material.

In 2009, two companies began working with water utilities on one that would be as easy as copper to install but resist both corrosion and chlorine:

  • The Lubrizol Corp., Ohio-based developer of FlowGuard multilayer pipe. An inner aluminum core to which inner and outer layers of chlorinated polyvinyl chloride (CPVC) are bonded, it’s a small ½-, ¾-, and 1-inch diameter bendable pipe with a pressure rating of 400 psi at 73° F.
  • Underground Solutions Inc., San Diego-based developer of the Fusible PVC trenchless installation methodology highly compatible with ductile iron water and sewer pipelines. Read “Five million feet and growing,” our February 2014 article about the process.

The result of the collaboration is a composite pipe called ServiceGuard. CPVC is highly resistant to chemical attack, providing corrosion resistance on the outside and oxidation resistance to chlorinated water on the inside. The stiffness of the aluminum core allows the pipe to retain a radius like copper and utilize the same compression-type brass fittings used with copper services to make connections to corporation stops and water meters.

The very tough CPVC outer layer is well-suited to the rigors of trenchless rehabilitation pull-ins and can withstand the normal installation abuse inherent in underground construction. With quick-burst pressures of more than 1,600 psi, the material has ample hydrostatic capacity to meet the demands of service line pressures, which seldom exceed 100 psi.

ServiceGuard is NSF 61-approved, made in accordance with ASTM F2855, and utilizes American Water Work Association standard C800 brass fittings.

Having specified the product for more than 50 projects, utilities find the off-the-shelf pipe easy to obtain, work with, and cost-effective since it’s usually priced below copper service lines.