CIPP Helps Pennsylvania Township Strengthen Its Sewers
October 27, 2011Abel Recon is nearing completion of a large cured-in-place pipe (CIPP) project that the company has undertaken using technology that is new to the project owner.
The relining project involves some 44,000 lf of sewer lines in Elizabeth Township, Pa., which is located about 40 minutes southeast of Pittsburgh and is a mix of rural and suburban communities. This CIPP project marks the first time that the Elizabeth Township Sanitary Authority has used ultraviolet-curing (UV-curing) technology as part of any of CIPP project.
The project is necessitated by an administrative consent order through the Allegheny County Health Department, requiring the Elizabeth Township Sanitary Authority to upgrade its system and drastically reduce its wet weather flows that have resulted in sanitary sewer overflows (SSOs). The first round of CIPP work occurred in 2009. This second round of CIPP — tagged at $2.080 million — started in May 2011 and is scheduled to be finished in November.
“This project is definitely one of the larger projects that we’ve done,” explains Rick Barnett, senior project manager for Senate Engineering, a Harmar,Pa.-firm that is the Authority’s consulting engineer and charged with designing and bidding these projects. “The purpose of the project was to address the administrative order regarding SSOs and to reduce inflow and infiltration into the system.”
The Authority’s system was built during the 1950s and comprised primarily of vitrified clay pipe, as found in most of the older sewer systems in the United States. Over the years, the pipes’ condition has deteriorated, resulting in cracked and collapsed sections of pipe, as well as root damage.
Extensive pipe cleaning and CCTV inspection was used to determine which pipes would be included in this project. “The pipes selected for rehabilitation were based on the NASSCO ratings system. The segments in this project contained fours and fives,” Barnett says.
The NASSCO grades, ratings and indexes are based on its Pipeline Assessment and Certification Program (PACP). Each NASSCO condition is assigned a numeric grade from 1 to 5, with 5 as the most significant defect. Defect grades are separated into Structural and Operation and Maintenance (O&M) categories. In the case of this project, the repairs were based largely on the Structural ratings.
“The consent order had a number of requirements, beginning with mapping and testing downspouts and routine CCTV work to determine where the problems were and where the excess water was entering the system,” Barnett says. “There were areas that had numerous problems and then there were areas that were in surprisingly good condition.”
The rehab project in 2009 repaired the sewer pipes that were 10 in. in diameter and larger; this project used felt liners and steam curing during CIPP. The 2011 project involves pipes 8 in. diameter and smaller.
“With the 2009 project, there was approximately 1,900 lf of CIPP work done using the felt and steam curing,” Barnett says, noting that CIPP was chosen because of its cost-effectiveness, as well as its minimal disturbance features. “After the 2009 project, we did some research on UV-curing and saw that it appeared to be stronger material and had a number of other advantages including good quality control during installation. We also liked that there are fewer styrene-related issues to deal with.”
Barnett says that the bid specs that went out to contractors included felt liners with hot water curing, as well as fiberglass-reinforced liners with UV curing “in order to get a good apples-to-apples comparison of the cost of the two technologies.”
Senate Engineering bid the project for up to 55,000 ft to be relined and an additional 10,000 ft of pipe to be camera inspected. A limited amount of manhole repair and removal of protruding taps were also included in the project. Abel Recon, located in Mountville, Pa., was awarded the CIPP project using UV curing technology.
In business since 2005, Abel Recon became the first Reline America licensee of its Blue-Tek liner method in 2007. Serving the Pennsylvania, Ohio, Maryland, New Jersey, Delaware and District of Columbia region, Abel Recon specializes in the infrastructure rehabilitation field, offering services in CIPP, pipe cleaning and inspection and infrastructure rehabilitation.
“This is the second largest project we have done using the Blue-Tek liner,” says Abel Recon general manager Hap Witmer. “It’s pretty straightforward. The biggest thing for us is that some of the right-of-way access is challenging, but the Blu-Tek system gives us an advantage in accessing those tough spots.”
For this project, Abel Recon is using two crews each to handle cleaning, inspection and relining duties. For the cleaning and inspection work, crews are using Aries camera equipment and Vac-Con jetters.
The Blue-Tek liner is a UV-light-cured lining system that is both a glass fiber reinforced pipe (GRP) and a UV-cured-in-place pipe that can be used for many different ovalities of pipe, which is attractive to cities that need to repair older systems. “We are seeing UV-curing being used more and more,” Witmer says.
For this project, Abel Recon is averaging 400-ft runs, which has been taking the UV-curing system about an hour to cure per run.
So far, Elizabeth Township Sanitary Authority has been pleased with the results of the technology. “This is the first time we have used it, and the relining work is progressing nicely. We are pleased with the results we are seeing so far,” Barnett says.
“There could be more [relining] work down the road but we are thinking that this [project] represents the majority of the work that needs done in the near term,” he says. “After this contract is completed, the Authority will continue with a long-term plan of sewer cleaning, inspection and repair and CIPP will continue to be used where it is most applicable and cost-effective.”
Sharon M. Bueno is managing editor of Trenchless Technology.