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 (DOT) District Seven 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.
Matt Dugas, maintenance engineer for the District Seven DOT, met with Snap-Tite representative Ryan Harrington to determine a viable solution for the culvert repair that would not disturb the road. The DOT 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. pipe was the best size pipe for the project. Another benefit of using the no-dig relining method was that the DOT crew could install it themselves saving the district money.
The high-density polyethylene (HDPE) 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 from 2 ft to 50 ft, and is available for culverts with diameters from 8 in. to 84 in.
The day of the installation, one of the damaged culverts deflected down to only a 59-in. opening. Harrington suggested cutting one end of the pipe into a bullet nose, a method used to push the liner into a deflected culvert. On site, the DOT crew cut the bullet nose on one end of a section of 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 pipe together, the crew only needed to use chains and a come-a-long. There was no specialty equipment required.
Both culverts were lined in one day and the DOT District Seven did not have to shut down the road, so the local traffic was not detoured 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.
