Over the years, installing cured-in-place pipe (CIPP) in large-scale projects for municipalities has become a specialty of Insituform. Over the past few months, the company has partnered with the Missouri Department of Transportation (MoDOT) and the St. Louis Metropolitan Sewer District (MSD) as a contractor on the I-64 Betterment Project.
According to MoDOT, the I-64 project is rebuilding 10 miles of highway, six overpasses and upgrading 12 interchanges. The $535-million project includes two years of closures of the interstate, with five miles closed in 2008 and another five miles closed in 2009.
Linda Wilson, community relations manager for MoDOT, had this to say about the project: “During the I-64 construction, MoDOT is allowing the utility companies to do upgrades to their system. All of the local utilities are taking advantage of that opportunity. Some of these utility betterments are items the companies would need to do in the future, but they can choose to complete now. It is easier and less expensive to do the work while MoDOT has the highway closed and the area opened up for the construction work.”
“In the long run, it is better to have all of the utility upgrades and the highway upgrades completed at the same time,” Wilson added. “All of these infrastructure systems will be new. We are pleased the utility companies are working cooperatively with our contractor so we can keep the I-64 project on schedule.”
The closure of the new I-64 project presented MSD with the opportunity to rehabilitate and update the surrounding sewers. Due to the closing of the highway for a period of time, major construction access was ideal and project sites were always open for installation equipment.
Insituform CIPP was chosen as the rehabilitation product due to its nondisruptive nature and quick installation. CIPP is a pipe within a pipe installed inside an existing host pipe without digging or disruption.
To install CIPP, resin-saturated coated felt tubing is inverted or pulled into the existing pipe. Hot water or steam is then circulated throughout the tubing, which cures the resin and forms a tight-fitting, jointless, corrosion-resistant pipe within a pipe. Service laterals are then restored using a robotically controlled cutting device.
According to Ronald Moore, MSD project manager, MSD frequently uses CIPP as a means of rehabilitating aging and deteriorating pipelines. In fact, the district has been using CIPP on major projects since at least 1990 on a yearly basis.
With the MSD for nearly 20 years, Moore has used numerous types of rehabilitation. He said that CIPP was selected for the I-64 Betterment Project because it allowed rehabilitation “to keep pace with the general contractor and stay in sync with project timelines.”
Moore also added that the use of CIPP fit well with the project’s special needs. “CIPP works well with the old systems, as we were able to change tube sizes quickly depending on the diameter of the sewer being rehabilitated. CIPP allows us to adapt very rapidly and eliminate project concerns,” he said.
As the low bidder, Insituform was awarded the contract to rehabilitate several thousand feet of underground pipeline using its flagship CIPP method. To date, the company has completed 59 installations of CIPP on this project and more than 17,000 ft of CIPP, ranging in diameter from 6 to 72 in.
The Insituform crew in St. Louis installed a 54-in. CIPP in Forest Park on March 6, 2009. The clay sewer pipe being rehabilitated was located on the edge of the St. Louis Zoo’s south parking lot, right next to a Forest Park biking trail.
The 85-ft installation went directly beneath I-64 construction, ending in the middle of the interstate. The 54-in. tube was inserted down a brick manhole into the combined sewer system using the air-inversion steam-cure (AISC) method. With the AISC method, air is used to invert the CIPP tubing and then steam power cures the resin. This not only makes difficult and steep projects possible, but it also reduces the amount of energy and water that is used during installation.
In fact, the environmental benefits of the AISC method are numerous. Water usage is cut down by nearly 95% in most projects, and energy used and time spent on a project is reduced.
The unique installation in Forest Park on March 6 required two of the CIPP crew members to travel down a manhole and walk through roughly 10 ft of 72-in. storm sewer to reach the downstream end of the installation. This required special attention to quality and, most importantly, safety requirements. Prior to entering the manhole, both crew members had undergone confined space training. These steps are required in accordance with Insituform’s Big Five rules for confined space entry that are observed on each and every CIPP job site. These rules ensure that the highest safety standards are routinely followed. Insituform’s Big Five confined space rules are:
1) Continually ventilate during man entry;
2) All entrants must be hooked to a lifeline/ retrieval system;
3) Calibrated meter used on every man entry;
4) Harness and rope used on every man entry; and
5) Confined space entry permit must be completed and posted in sight of manhole.
During the installation, multiple cyclists, runners and walkers passed by the site, taking advantage of the warm weather. Little did they know that a 54-in. CIPP was being installed right beneath their feet. The project was a great example of how CIPP is a less disruptive solution for sewer pipeline rehabilitation.