In fall 2010, Indiana DOT crews lined 14 corrugated metal culverts — 2,257 linear feet total — with HDPE. At $1.2 million, they saved taxpayers about 50% on labor compared to contracting the work. Oval pipes ranged from 30x46-inch to 72x102-inch; round pipes from 48 to 84 inches in diameter. Photo: Indiana DOT
Once the HDPE liner's installed, it's important to build a bulkhead or plug to secure material in the annular space during grouting. Grouting was contacted separately; Temple & Temple Excavating and Paving's Patrick Howser puts the finishing touches on a culvert on I-65 in Indiana. Photo: Indiana DOT
By Steven Hauersperger, PE
Owner: Indiana DOT
Project: Slipline 14 round and oval corrugated metal pipes with in-house crews
Product: Snap-Tite HDPE culvert lining system
Manufacturer: ISCO Industries LLC; Louisville, Ky.
Distributor: CPI Supply; Bedford, Ind.
Grouting contractor: Temple & Temple Excavating and Paving Inc.; Salem, Ind.
The stimulus package was welcome, but given our infrastructure's enormous need for repair and rehabilitation, it didn't alleviate the need to stretch maintenance budgets as far as possible. The year the American Recovery and Reinvestment Act of 2009 was signed, one agency set out to prove contractors could lower bids for trenchless pipe rehabilitation — so-called “specialized” work — and succeeded.
Until the introduction of liners that don't need to be mechanically joined, contractors have owned the market for sliplining and other rehabilitation methods that require special equipment to fuse liner segments together for a watertight seal. But in 2009, the Indiana DOT identified an easy-to-install product that met department specifications and initiated a pilot program in one of its six districts to line corrugated metal culverts with high-density polyethylene (HDPE) in-house.
Most of the corrugated metal pipes in the LaPorte District's 150 culverts are at least 30 years old and reaching the end of their design life, a familiar scenario for public works departments regardless of service area size or location. Agency maintenance crews routinely slipline shorter, smaller-diameter culverts — pipes less than 40 feet long and 30 inches in diameter — but under the pilot program would tackle pipes up to 305 feet and 72 inches.
Maintaining traffic flow usually makes replacing interstate under-roadway stormwater culverts and spillway pipes costly. So to test the viability of lining as a rehabilitation method, the district targeted assets under I-65 and I-94, two of the state's busiest and most traveled highways.
“With replacement, the cost to maintain traffic in some areas was equal to or more than the cost to line,” says District Spokesman Jim Pinkerton. “Sliplining enabled us to improve pipe condition for much less.”
Managers specified the Snap-Tite culvert lining system* manufactured by ISCO Industries LLC of Louisville, Ky., and distributed in Indiana, Illinois, and Michigan by CPI Supply of Bed-ford, Ind. A major attraction was that it requires little special training and no specialized equipment. Each end of the liner has a patented male/female connection that allows installers to snap sections together piece by piece to the desired length and then push the assembled liner into a pipe. Crews then fill in the annular space and any voids between pipe and liner with grout.
For pipes, section lengths range from 2 to 50 feet; for culverts, diameters from 8 to 84 inches.