With several miles of cast iron water mains in its system since the 1950s and 1960s and shifting clay soil, the city of Fort Wayne, Ind., is no stranger to water main repairs.

“The combination of the old pipe with our dry, clay soil during the summer often leads to multiple main breaks for us,” said Mike Kiester, manager of City Utilities Engineering/ESS for the city of Fort Wayne. Last summer was especially dry, and we were seeing fractures in the soil going down about 3 or 4 feet. When you have soil shifting that deep, it keeps twisting those old cast iron pipes and causing main breaks.”

Last year, the city reached the end of its patience with one particular corroded 24,000-foot water main and made the decision to replace it. The water main, parts of which were 60 years old, had become a growing maintenance hassle in the city’s Anthony Wayne Village neighborhood.

“Our goal is to replace at least 1 percent of our water infrastructure per year, if our budget allows,” Kiester said. “We’d had to repair more than 100 leaks and breaks in this main over the years, so we decided it was about time to replace it with a non-corrosive thermoplastic pipe material for lower maintenance and increased longevity.”

Since the main was located in a densely populated residential area (550 homes), the city and its contractor, Atlas Excavating Inc., of West Lafayette, Ind., decided that replacing the water main via horizontal directional drilling (HDD) was the least disruptive and most cost-effective way to install the new water main.

Since the main was located in a densely populated residential area (550 homes), the city and its contractor, Atlas Excavating Inc., of West Lafayette, Ind., decided that replacing the water main via horizontal directional drilling (HDD) was the least disruptive and most cost-effective way to install the new water main.

“HDD reduces inconveniences to customers and lowers restoration costs when you’re working in a residential area,” Kiester said. “With an open trench installation, we would have had to cut through sidewalks and driveways with the added cost of replacing them. And, with all of the utility lines installed over the years, there’s not enough room left for a trench in the right-of-way. With HDD, we can make good use of the limited space available and go under these obstacles. It’s considerably less intrusive.”

Going on a recommendation from Atlas Excavating, Kiester specified CertainTeed Certa-Lok C900/RJ restrained-joint PVC pipe, a non-corrosive thermoplastic pipe compatible with the traditional pipe fittings the municipality already had in stock.

“The Certa-Lok pipe’s ability to integrate with the fittings and other replacement parts we have on hand was a selling point,” Kiester said. “We try to standardize to keep our maintenance material inventory down as much as possible.”

Twenty-foot lengths of Certa-Lok C900/RJ restrained-joint PVC 6-inch and 8-inch pipe were assembled piece-by-piece during pipe pullback, allowing for smaller work areas in a densely populated neighborhood.

Certa-Lok pipe is easily assembled during the pipe pullback process with spline-locked couplings in 20-foot lengths. This allows pipe installation to keep moving at a steady pace and use a smaller work area.

“Since the pipe is assembled piece by piece during pullback, it doesn’t take up as much space,” said Casey Dillon, project manager for Atlas Excavating. “You don’t have to pre-fuse hundreds of feet of pipe above ground throughout the neighborhood. So, it takes less time to assemble and causes less disturbance than fused pipe.”

Atlas Excavating began work with a crew of four in May 2010, using a Vermeer 24x40 directional drill, with 24,000 pounds of pullback and 40,000 pounds of radial torque, and a Vermeer drilling fluid mixer. The job presented challenges from the start, Because of the limited space, small distances between each home, and location of existing utilities.

“Putting in the new pipe was like threading a needle through what little soil we had left,” Dillon said. “When you’re doing a main replacement, the old one is still in service, so you have to go around it. Plus, the storm and sanitary sewer laterals didn’t go in a straight line like you would expect. We found some of them 17 to 20 feet from where they were supposed to be. We had to do a lot of diving down to go around them.”

Another challenge as the project moved into summer was drilling through clay hardened by the unusually dry weather. The crew used a variety of specialty drilling fluids to lubricate the boreholes, but the dry clay still provided formidable resistance, slowing the pace of the project. Still in service, the old water main experienced a few more main breaks as the project went on around it, forcing city maintenance personnel to come out to the site and make repairs.

Fighting through these obstacles, the crew made more than 60 bores, averaging 380 feet in length at depths ranging from 4 to 7 feet, installing approximately 10,000 feet of 6-inch and 13,500 feet of 8-inch restrained-joint PVC pipe. The pipe installation was finished in November 2010, and the pipe passed pressure testing in April. Atlas Excavating then completed the project by connecting the 550 copper service pipes, and the new water main was brought into service by the end of spring. The previous water main was then disconnected, sealed off and abandoned.

Though frustrated with the many obstacles of the project, Atlas Excavating was pleased with the performance of restrained-joint PVC pipe in this HDD application. The combination worked well together and proved to be a better choice for the project than an open-trench installation of HDPE pipe.

Directional drilling was challenging because of the limited space, small distances between each home, location of existing utilities, and hard clay soil.

“Directional drilling helped us keep disturbances down quite a bit,” Dillon said. “It was the only way to do this job. Open cutting would have been nearly impossible with all of those houses around and the utility lines we dealt with. The Certa-Lok pipe also helped, as it didn’t take long for us to assemble, and we didn’t have to worry about it blocking people’s driveways, like fused pipe.”

As the city of Fort Wayne continues to replace aging cast iron water mains, it looks forward to a decreased need for repairs as more non-corrosive thermoplastic pipe is added to the water distribution system.

“At the rate of replacing 1 percent of our infrastructure a year, we’re saying that we want our pipe to last up to 100 years,” Kiester said. “Hopefully, with the new thermoplastic pipe we are installing, we can increase the longevity of our water mains and meet that objective.”

John Coogan is with CertainTeed Corporation.