August 31, 2016
In the United States, many manholes were traditionally built of brick. These masonry manholes were designed to provide structural durability and protect against chemical attack. Although brick manhole construction has now been replaced by precast concrete, many masonry manholes still exist throughout the country. Wardsville, Mo., is an example of a small village where masonry manholes are present. These manholes were originally built in the 1960s; however, after more than 50 years in service, they were in need of rehabilitation.
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Wardsville, is located in Cole County, Mo., about five miles south of Jefferson City. The population of this village has doubled in the past 10 years, but it has still maintained its quaint, small-town, country ambiance. This, together with its central location and excellent schools, make the village an attractive place to live. Cost savings in this village, as in most small towns, is of utmost importance and making efficient use of tax payer dollars to restore (rather than replace) infrastructure would benefit all the town’s residents.
Many of the original brick sanitary sewer manholes in Wardsville were in need of attention and rehabilitation due to the effects of corrosion. Many had irregular bricks and were missing mortar. Structural rehabilitation was clearly necessary in order to restore the integrity of these sanitary sewer manholes.
Gary Frank, long-time water/wastewater operator in Wardsville, contacted Mid-MO Environmental, an Epoxytec Certified Applicator, requesting that it inspect several of the village’s sanitary sewer manholes. Mid-MO Environmental was founded in 1997 by Shawn York, a native to the Jefferson City area. The company has been involved in on-site sewer system service, repair, and maintenance for more than 15 years. The company’s portfolio includes mainline/lateral jetting, camera work, commercial/municipal vacuuming, hydro excavating, trenchless rehab, grout injection, point repairs, and large-diameter structure rehabilitation (i.e. manholes, lift stations, tanks, etc.). Mid-MO Environmental specializes in waste management. The company is a certified contractor of Epoxytec, manufacturer of epoxies, urethanes, and related specialized products for the water and wastewater industries.
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Upon examination of the structures, Mid-MO Environmental, in conjunction with Epoxytec representative Marilyn Baron, determined that seven manholes were in need of rehabilitation, mostly due to inflow and infiltration (I/I). All seven of the manholes were brick structures measuring 4 ft in diameter and 10 ft in depth. The benches within the manholes also needed to be built or re-built, and new lids and rings were also necessary.
It was determined that Epoxytec’s Mortartec Ceramico would be used as a stand-alone system to repair six of the seven manholes. The seventh manhole’s condition was more seriously declining because it was upstream from a previously removed old lagoon. This manhole, unlike the others, would require Epoxytec’s Structural CPP as a topcoat over the Mortartec Ceramico in order to provide additional structural support.
Surface preparation of the structures was simple: a high-power pressure wash of 4,000 psi for the walls, bench, and other parts of the manholes. Major voids within the manholes were then filled with fast-setting hydraulic cement intended to structurally patch, stop leaks and plug water.
Mortartec Ceramico was then applied at 125 mils to all seven of the manholes. Mortartec Ceramico is a highly advanced formulated epoxy blend incorporating cutting-edge epoxide technology with proprietary engineered curing agents. This blend is combined with a specific balance of Portland cement, hardened ceramics, graded silica aggregate, synthetic fibers, and silica fume to produce one of the most coveted mortars in the industrial market today. Once cured, the result is a smooth mortar application with the hardest surface in the industry. In addition to exhibiting excellent acid resistance, unlike any mortar technology before it, Mortartec Ceramico also has outstanding adhesive properties, barrier sealing capabilities, and tolerances, as well as out-gassing, hydrostatic, and MVT reduction – perfect for the highly corrosive wastewater environment. It is designed to be used either as repair material or a stand-alone liner.
Once the epoxy blend cured, the seventh manhole was addressed. Epoxytec’s CPP was troweled on at 125 mils in order to provide an additional corrosion barrier. CPP is a two-component epoxy paste with superior adhesion that is moisture insensitive, highly adhesive, chemical resistant, 100 percent solids, and high strength. It is truly versatile and can be used as an adhesive, patching filler, or even a high-build, stand-alone protective liner. It is blended with reinforcing agents and various fibers. When cured, Epoxytec CPP creates reinforcement as a fiber-reinforced polymer (FRP) with high flexural properties. It addition, it contains no solvents (no VOCs), making it safe for use in confined spaces. CPP bonds to concrete, steel, wood, brick, some plastics and most construction materials. The choice of CPP would give the most severely deteriorated manhole the additional support and protection it needed.
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The rehabilitation of these brick sanitary sewer manholes using Epoxytec protective products resulted in structures that are quite possibly stronger than they were when originally built. The products’ combination of excellent chemical resistance and ultra-high adhesion not only restored these masonry manholes, but also protected them from future corrosion. Wardsville residents can feel confident that their tax dollars were spent wisely and that these sanitary sewer manholes will not need to be addressed again for many years.