Bringing Concrete and Asphalt Manhole Casings Up to Grade

The city of Ironton, Ohio, is nearing completion of a year-long project to re-line its sanitary sewer system. Part of the project included bringing 1,033 manhole casings up to grade; not an easy task. E.L. Robinson was the engineering firm retained to plan and implement the project while FeeCorp Environmental Company handled the repairing and replacing of the manhole casings for the project.

The manhole part of the project consisted of coating the interiors and replacing crumbling, leaking manhole chimney sections, adding new frames and lids, and bringing the new manhole casings up to grade, according to Michael Keith in an April 2010 article he wrote for Trenchless Technology.

FeeCorp started its portion of the project in October 2009. Aside from stopping for three weeks due to cold temperatures, FeeCorp has worked year round on the manhole casings. "We averaged about 40 casings a week," explains Ed Jones, FeeCorp's general manager of operations.

In order to replace the manhole chimney sections and bring the manholes up to grade, both the manhole lid and some of the surrounding asphalt or concrete needed to be removed. "The manhole chimney section is 10 percent of the manhole structure but is responsible for 50 percent of the leakage," according to Keith's article.

FeeCorp. encountered both asphalt and concrete road surfaces during the project and employed several methods for removing and bringing the casings up to grade, Jones says. In some of the concrete surfaces, the company also encountered thick rebar, which presented a challenge when cutting. While FeeCorp Used jackhammers and core saws to cut through the hard concrete with rebar, the company found the most time efficient method for areas without rebar was a manhole removal system attached to a compact track loader. Jones said the company used both the Mr. Manhole system and the Coneqtec/Universal HS-57 Manhole Saw.

These manhole removal systems are designed to attach to the manhole casing frame and then cutting teeth cut into the road surface. After the depth of cut is reached, the system lifts the manhole casing frame and the cut road surface out at the same time, allowing the next step in the process to be performed.

Jones says the systems were a great asset because one man can run the system and do the job completely.

Once the old casings, rebar and road surface were removed, FeeCorp worked with a local ready mix company to pour the new concrete and bring the casings up to grade, Jones says. Finally, new sealed manhole frames and lids replaced the old ones.