Many culverts in the U.S. were installed 40 to 50 years ago and now have exceeded their design life and need repair. In this case, two 72-in.-diam. corrugated metal pipe (CMP) culverts in White Oak, Miss., started to fail. The Mississippi Department of Transportation (MDOT) District 7 feared that the road might collapse if the culverts were not repaired in a timely manner. Shutting down and digging up the road to fix the problem was not an option, as it would detour traffic 15-20 miles away from the public’s normal driving route.
An alternative solution was necessary.
Matt Dugas, maintenance engineer for District 7, met with Snap-Tite representative Ryan Harrington to determine a viable solution for the culvert repair that would not disturb the road. MDOT chose to reline the old culverts instead of using a dig and replace method. During the initial inspection of the CMP in the fall, it was decided that 63-in.-diam. Snap-Tite pipe was the best size pipe for the project. Another benefit of using the no-dig Snap-Tite relining method is that the MDOT crew could install the pipes themselves, thus saving the district money.
The high-density polyethylene (HDPE) Snap-Tite pipe has a patented male/female machining at each end of the pipe sections. The machined sections are “snapped” together, piece-by-piece, and pushed into the full length of an existing pipe. Any annular space and voids between the old culvert and new liner are filled in with grout. The pipe liner is available in lengths ranging 2 ft to 50 ft, and is available for culverts with diameters anywhere from 8 in. to 84 in. Snap-Tite also meets American Association of State Highway and Transportation Officials (AASHTO) Standard M326 for rehabilitating culverts.
The day of the installation, one of the damaged culverts deflected down to only a 60-in. opening. Harrington suggested cutting one end of the Snap-Tite pipe into a bullet nose, a method used to push a Snap-Tite liner into a deflected culvert. On site, the MDOT crew cut the bullet nose on one end of a section of Snap-Tite pipe in order to get it through the deflection of the old pipe. Once the bullet nose pushed through past the deflection point, the rest of the pipe slid through the old pipe with ease.
Then to snap the sections of Snap-Tite pipe together, the crew only needed to use chains and a come-along. There was no specialty equipment required.
“I was amazed with the strength and durability of the liner. Yet, it was flexible enough to conform to the shape of the deflected host pipe,” said Dugas. “We field-cut a bullet nose with relative ease, and the 63-in. liner slid right through a problem joint with only 59 in. of clearance. The joints are solid, with absolutely no infiltration, and the ease with which they snapped together was unexpected.”
Both culverts were lined in one day and MDOT District 7 did not have to shut down the road, so the local traffic was not deferred and continued to flow normally. This was the first major installation of Snap-Tite pipe in Mississippi, and at the end of one day, it was a success.
Due to the Snap-Tite system’s installation flexibility and cost-effectiveness, it continues to provide successful results for many projects throughout the U.S. and internationally.
For more information on Snap-Tite, please visit www.culvert-rehab.com.
