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Field Report

Oval Culverts Rehabilitated with Culvert Lining Solution Wallaceburg, Ontario, Canada

The ProblemUnder roads and highways, many corrugated steel pipe (CSP) and concrete culverts are reaching the end of their useful design service life. Installed more than 25 years ago, these CSP’s are so significantly rusted that a danger of sink holes, road collapse or flooding exists. A culvert is a conduit designed to collect water from one area, the inlet, and discharge it out the other end, the outlet. A culvert is in failure mode when water escapes the culvert pipe before exiting the outlet end. As a metal culvert ages, it weakens, separates at the joints and develops rust and holes. As a result, water travels outside the culvert and washes away the roadbed, weakening the entire area and compromising the pavement surface. Left unrepaired, it will only get worse with time. Separated joints and the fatiguing metal will eventually give way and ultimately road failure will occur. Similar conditions happen with concrete culverts when the joints separate, the concrete spalls, cracks and fails to perform as it did when it was originally installed. Culvert relining is popular with many owners of this infrastructure. Since as many as 40 percent of the culverts under roads in Ontario are oval, there was a struggle to find the most appropriate type of pipe for relining them. Until recently, high density polyethylene (HDPE) pipe, designed to reline culverts, was only available as a round product. The options for repairing failing oval or elliptical steel culverts was to reline them with two round pipes or to simply re-

move and replace them. While relining is typically the best option for repairing ailing steel and concrete culverts, main-taining flow capacity is a significant concern. Relining an oval-shaped pipe with two round pipes often causes a loss of flow capacity. In many cases, a loss of flow is unaccept-able. Further, two smaller pipes inside a larger pipe increases the risk of debris build up and flow restriction.

The SolutionOval HDPE pipe was the solution. The Ministry of Transporta-tion Ontario (MTO) tendered a contract on Highway 40, just north of Wallaceburg, to reline five elliptical shaped steel culverts with oval HDPE pipe, the first of its kind under an Ontario Highway. Snap-Tite representative Brian Zagrodny worked with MTO staff to develop this opportunity and to bring this new technology to the Ontario market. The project was to reline the failing elliptical steel culverts with oval HDPE pipe, increasing the flow capacity of each of the existing culverts. Snap-Tite has a patented male/female machined joint at each end of the HDPE that allows it to be ‘snapped’ together, piece by piece, and pushed into the full length of the existing pipe. Unlike other so-called ‘rehab systems,’ the annular space between the host pipe and the new Snap-Tite pipe is filled with a low density cellular grout, which fills in any voids between the roadway and culvert, delivering a truly ‘rehabbed’ culvert. Snap-Tite pipe can be ovaled to fit into elliptical shaped culverts. With the introduction of oval Snap-Tite HDPE pipes,

The oval Snap-Tite pipe liner is slid inside the old pipe.

The oval Snap-Tite pipe is snapped together on site before being slid inside the old culvert. No fusion equipment is necessary to join the pipe.

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we are now able to match, and often increase, the flow ca-pacity of an existing culvert, making relining more desirable than removing and replacing the existing steel culvert.

The InstallationComprised of five separate elliptical culverts, the Wallace-burg reline project spanned three km under Highway 40. Installed approximately 30 years ago, these culverts were no longer functioning properly. Although the Highway 40 culverts were reaching failure mode, the MTO’s active main-tenance and inspection program caught them in time allow-ing slip-lining to be a viable permanent solution. Most of the existing culverts for this MTO project were approximately 27 m long and measured approximately 838 mm x 1246 mm in elliptical dimension. The project was designed in the spring of 2012, tendered and went to construction in the early fall. Initially scheduled to take three weeks, the work was completed in only two weeks. The contractor on the project was Newmar-ket, Ontario-based Provincial Underground Services, Ltd. Members of the Provincial and Snap-Tite teams along with the MTO took final measurements of the pipe to ensure that the largest liner pipes would successfully fit. After inspec-tion, the team concluded that ovalized Snap-Tite pipe with dimensions of 762 mm x 1041 mm would work. Provincial began by mobilizing to the site, staging the liner pipe at each of the five different locations, prepping the sites and cleaning the culverts. The Snap-Tite liner pipes were sup-plied in 7.5 meter lengths, making it easy to insert into the existing culverts with very little site disturbance. Provincial, and its crew started at the northern most culvert and worked their way south. They inserted each liner section, one at a time, aligning the male/female ends and winching the sections together with chains, binders and

come-a-longs until all the pipes were lined and “snapped” together. Once lined, the team installed bulkhead end seals at each end of all the lined pipes. The use of bulkheads captures and retains the grout flowing in the annular space between the liner and host pipe. Grouting is a critical com-ponent to any relining project. If you reline a structure with-out grouting it, the problem is only partially fixed. Grouting stabilizes the liner inside the host pipe, filling any voids and holes created as a result of the failing pipe. This process is likened to backfill when a pipe is dug up and replaced. “Snap-Tite oval pipe was easy to install in the wet and muddy conditions, even with a smaller crew,” said John Gawn of Provincial Underground Services Ltd. “The pipe was really forgiving and we were able to push it through despite the deflections in the host pipe, where other liner pipes wouldn’t have been able to fit into. The Snap-Tite pipe installed exactly as the manufacturer stated it would and I look forward to using it on other similar projects.”

ConclusionMembers of the MTO and other townships, municipalities and engineers were all on site to see the Snap-Tite process take place. All were impressed with the ease of installation. The MTO was extremely happy with the outcome of the project and are happy to know this oval technology is avail-able for future reline projects, saving them time and money. The Snap-Tite liner pipe has proven to be a great product for culvert lining. The pipe is easily aligned and snapped together especially in its oval shape.

About Snap-Tite• Meets AASHTO Standard M326 for rehabilitating cul-

verts. • Offers flexibility for insertion into misaligned concrete or

rusted deteriorated corrugated metal pipe. • Offers a safe method for installers and doesn’t require

traffic control. • Tough but lightweight, the Snap-Tite® joint makes a

solid water-tight mechanical connection that can be pushed or pulled.

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.

The oval Snap-Tite pipe liner is installed and grouted into place.