September 2014, Vol. 69, No. 9
Rehabilitation
Las Vegas Embraces Polymer Concrete Manholes
The Clark County Water Reclamation District (CCWRD) has been addressing system wide corrosion concerns in recent years.
The 661 Rehabilitation Project was unique in size and scope. Jon Osborne, the consulting engineer for Brown and Caldwell in Las Vegas, said, “From the very start, it [the project] provided many challenges. It required five different alignment adjustments to improve hydraulic deficiencies, conflicts with adjacent utilities and ongoing maintenance issues.”
The five different alignments addressed approximately 12,000LF of pipe and approximately 181 manholes to be replaced or rehabilitated. Logistically it was a real challenge. The 661 Rehabilitation Project required mobilization to four different areas around the county with split inspection groups. Corridor coordination was necessary with NDOT, the Las Vegas convention center, and four different casinos.
Lining was scheduled for 88 of the structures with the remaining planned as new manholes. The original rehabilitation specification was originally written as cast-in-place-pipe (CIPP) for the pipe and cast-in-place-manholes (CIPM) for the manholes. An addendum was added to allow for polymer concrete manholes. This was a product that CCWRD had been evaluating for more than a year. Brown and Caldwell were pleased to add it as an alternative product. Unlike the CIPM material, polymer concrete did not require any field curing time which allowed for a faster installation process. With the severe logistical concerns, the polymer manholes were a significant time saver.
Osborne indicated that he had a real comfort level with the polymer product. “It installs just like a standard manhole,” he said. “The difference being, it doesn’t require any coating or welding. It won’t corrode and it carries a 50-year corrosion warranty. We were happy to include it in the bid process. With the Harber Company, we had an excellent contractor who was working hand-in-hand with a quality vendor in Geneva Polymer Products. One of the most difficult things about this project was the in-system rebuild of the benches on some of the manholes. The rebuilt bench and polymer integration was critical, and it was comforting to know we had a contractor and vendor the caliber of Harber and Geneva.”
Rick Rieken with Harber Company indicated that the Armorock manholes were of great help in overcoming some of the logistical concerns. “We had multiple locations all over the county,” Rieken said. “In an effort to meet all the coordination concerns related to local casinos, we found ourselves working all hours of the day and night. The polymer concrete manholes eliminated a good portion of the installation process that we were commonly used to with coatings. We didn’t have to wait on the coating inspectors for sign-off. Spark tests and dolly pulls weren’t necessary with this product. This shortened the installation process significantly as well as shortening traffic control concerns. There are some real definite advantages to using this type of product for both the contractor and the owner.”
Dale Johnston with CCWRD stated: “We knew that this project was going to be a real test. We were very fortunate to have a contractor and vendor that worked in sync on the project. Any concerns we may have had evaporated very quickly by a quick response from the contractor or the vendor. Some of these manhole rehabs were very difficult. A few of the small, older manholes had as many as four inlets. Rehabbing a bench like that with flow through plugs and integrating the polymer riser section is a real art. We were extremely pleased with the Armorock manhole product. It had been placed in our system for approval under the usual vetting process. We were fortunate that the approval process finished prior to the bid date of this project so it could be included.
“We have been looking for a sustainable structural product that could handle our long term corrosion concerns,” Johnston added. “We feel that a product of this type is superior to other available alternative products. Our industry cannot keep dealing with ongoing infrastructure refurbishment every 10 to 20 years – we just can’t afford it. The Armorock product carries a 50-year corrosion warranty, and if it is a 100-year product, it will be one of the many tools that we can now use to reverse the trend and greatly increase our infrastructure life cycle.”
FOR MORE INFORMATION
Geneva Polymer Products: (702) 479-1772, www.armorock.com
Comments