Manhole risers help growing community maintain infrastructure

Problem: Per the U.S. Census Bureau, the city of Cookeville (population 35,000) is the largest of Tennessee’s 20 “micropolitan areas,” defined as “smaller cities which function as significant regional economic hubs.” So, Cookeville is “officially” a growing town in a bustling region, and the city’s Public Works and Water and Sewer departments feel pressure to maintain infrastructure efficiently and cost-effectively.

Solution: One way they do this is by using American Highway Products Pivoted Turnbuckle Manhole Risers when raising manholes to grade. The city began using these particular adjustable risers in 1999 and since then has ordered and installed more than 2,000. “I’ve been here 13 years as a foreman and now purchasing officer in the Water and Sewer Department, and in all that time the American Highway Products riser is the only riser we’ve ever used here,” says purchasing officer Nate Beaty. “In my time installing and now ordering them, I don’t know of any failures or returns. When we install them right, they don’t even rattle.”

Result: Riser installation is simple; it usually takes one person 5 to 10 minutes to clean out the original rim with a wire brush, set in the lightweight riser (a shaped ring of durable galvanized steel) and adjust the turnbuckle with a screwdriver used as a lever — this applies thousands of pounds of force and seats the riser tightly and permanently. “We never needed a class; it’s an easy skill to pass on,” says Beaty. “And like I say, no failures!” 888-272-2397; www.ahp1.com

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Utility employs better technology to raise exposed manhole to grade

Problem: MidCoast Council is a small local government area in New South Wales, Australia, responsible for public infrastructure in its region, including the raising of manholes to grade after new paving. Typically, this has been a slow, labor-intensive process due to the weight, relative fragility and imprecision of concrete rings. This wasn’t an attractive solution for MidCoast when faced with dramatically failing pavement in a heavy-use intersection with lots of bus and large truck traffic — the cracked and subsided roadway exposed 2 inches of manhole rim, creating an obvious safety hazard. They had to act quickly to repair the roadway, using a fast and durable technology that would permanently fix the intersection and expose the public and repair crews to minimal risk.

Solution: The council chose a Cretex PRO-RING supplied by ISC Services to make the repair. The manhole grade adjustment system is based on rings made from high-strength lightweight expanded polypropylene. The rings are precisely-sized, lightweight — 14 pounds rather than 240 pounds for a typical concrete ring — and much more efficient to install, usually saving hours of labor and requiring smaller crews. Like concrete, EPP rings have a 100-year life cycle and don’t degrade or deform under load.

Result: In one morning, MidCoast excavated and installed a 4-inch finish ring (secured and sealed with M1 adhesive) and placed a new heavy-duty cover and frame on top of the Pro-Ring. After backfilling, compaction, and cold mix, the rehabilitated intersection was immediately opened for use by heavy vehicles. 800-345-3764; www.cretexseals.com

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City relies on manhole replacement system to complete massive repair and restoration project

Problem: Several years ago, the city of Ames, Iowa, began a massive-scale repair and restoration of its sanitary sewer system. The team was warned that with projects such as this, residents can get anxious when their street is shut down and the sewer is torn up, especially when the repairs drag on and on.

Solution: In an effort to reduce the project’s timeline, materials, labor and overall costs, the city’s engineering team decided to use a Mr. Manhole cutter to complete the work. “The manhole technology is incredibly fast,” says Eric Cowles, a civil engineer with Ames. “On a good day, depending on the depth of the rehab that has to be done, our contractor is knocking out eight to 12 a day very easily.”

Result: The Mr. Manhole system transformed the way that Ames executed this large-scale project. The system is incredibly fast, and on a good day, depending on the depth of the rehab that was being done, contractors completed eight to 12 manholes. Everything was done quickly and efficiently with minimum impact to the public. “Overall, everything has been really smooth,” says Cowles. “We were kind of warned that sometimes on these projects, residents get a little antsy. You shut down their street, tear up the sewer, and that really hasn’t been a problem here.” 567-242-2221; www.mrmanhole.com

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Epoxy used for coating new large-diameter manholes at Arizona housing development

Problem: At a new housing development called El Cidro, the city of Goodyear, Arizona, elected to coat 14 new 60-inch manholes with epoxy to extend their life spans. The manholes were as deep as 36 feet.

Solution: For this project, Manhole Coatings chose to use Neopoxy’s high-strength, corrosion-resistant NPR-5304 epoxy system applied via plural component spray equipment. First, the manholes were pressure-washed at 4,000 to 5,000 psi. Although NPR-5304 is a totally hydrophobic product and can cure underwater, hot air was then blown on the surface for 15 to 30 minutes in order to get maximum adhesion. Following this preparation, NPR-5304 was sprayed onto the surface in one pass as a monolithic 125 mil coating.

Result: The project was completed successfully and the manholes were in service shortly after application. Through this application of NPR-5304, the life span of the manholes was extended by approximately 50 years. 510-782-1290; www.neopoxy.com