Approaches to Sealing

Manufacturers offer a wide variety of systems for stopping clear-water infiltration to manhole chimneys and structures

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Manhole rehabilitation is an essential weapon against infiltration of clear water to sewer systems. Manufacturers have developed a wide range of approaches to sealing or replacing the manhole chimney and rehabilitating the entire structure.

Numerous materials — grouts, mortars and sealants — can be used to rehabilitate manholes. The manufacturers listed here provide not just materials but systems for manhole repair. They range from devices for applying sealants to tools for replacing structural components. Clearly, municipal managers have a host of technology options at their disposal when planning manhole rehabilitation initiatives.

Cementitious application plant

The CG-550 Workhorse series of grout plants from Perma-Liner Industries allows continuous mixing and pumping. The skid-mounted unit injects cement, bentonite, cement/bentonite, cement/sand, non-shrink self-leveling grout, and most packaged grout mixes. The system’s balanced design enables workers to prepare another batch in the 45-gallon mixing tank, while the 10-gallon hopper feeds the 8-gpm, progressive-cavity, rotor-stator grout pump. The mix tank is equipped with baffles, bag breakers and variable-speed high-efficiency paddles.

The trailer-mounted grout plants have a 45-gallon mixing tank, 30-gallon hopper, and 3-inch, positive-displacement pulsating piston pump that disassembles with only a hammer. The trailer has springs, lights and work platform. Operator controls on both plants are centrally located. 866/336-2568;

Wastewater structure protection

Spectrashield from CCI Spectrum Inc. stops infiltration in manholes through the systematic layering of polymer resins. The stress-skin panel effect imparts structural strength, while multiple layers eliminate groundwater intrusion, restore the profile of structures, and provide a light-reflecting, impervious barrier to environmental penetration. The University of Houston tested the product for infiltration with hydrostatic pressure at 15 psi and found no water intrusion. In less than one hour, contractors can line a 7-foot-deep manhole with minimal disruption to the surrounding environment. 800/284-2030;

Rehabilitation kit

The rehabilitation kit from Infrastructure Repair Systems Inc. reconditions manholes in three steps. Once the manhole is cleaned, the water-borne epoxy primer is applied, often with a garden sprayer. Infragard, applied with a brush or trowel, comes next. The two-part epoxy topcoat stops infiltration or exfiltration. The third step is Chim Coat, a flexible, two-part epoxy chimney coating that expands and contracts with changing temperatures and traffic loads. The result is a high-strength structural bond that is corrosion-resistant and impermeable. 877/327-4216;

External sealing system

The 30-mil-thick Infi-Shield Gator Wrap from Sealing Systems Inc. prevents infiltration and erosion by creating a watertight seal around manholes, catch basins and pipe joints. The stretchable, self-shrinking, intra-curing halogenate- based rubber resists harsh soil conditions and acts as a barrier to root intrusion.

The seal’s external face is coated with a cross-linked reinforced butyl adhesive. The wrap stretches around the joint, then overlaps to form a cross-link and fused bond between the rubber and adhesive. No special installation tools are required, and the seal can be backfilled immediately. 800/478-2054;

Keeps out water

The Riser-Wrap seal from Pipeline Seal & Insulator Inc. is a two-layer system designed for corrosion and sealing protection on manholes and vaults. It seals joints against groundwater infiltration, and is tolerant to soil stress, ultraviolet light and freeze-thaw conditions. The inside layer is a visco-elastic adhesive liquid sealant covered by a 1/8-inch-thick heat shrink sleeve of cross-linked, high-density polyethylene. Applications are for precast base, cone, risers and cast-iron frame manholes. 800/423-2410;

Manhole chimney reconstruction

The cutter/extractor system from Mr. Manhole dry-cuts through asphalt or concrete to remove manhole castings without manual labor in five minutes. The 800-pound cutter operates on any skid-steer loader and most posthole augers. Sixteen teeth on the tooth plate cut holes from 50 to 58 inches. The swivel-bearing centering plate adjusts from 22 to 29 inches to accommodate various lid sizes.

The cutter/extractor locks into the manhole frame and cuts through the road, extracting the road overcut and frame. After workers seal the insert liner and place it on the manhole cone, a ring saw system cuts the liner to the appropriate slope and height. Once the frame is reinstalled, workers place epoxy-coated rebar and pour concrete to road level, rendering the frame and lid structurally sound. The rebuilt collar is watertight and impervious to gases. Five men can repair 10 manholes per day, or in about the same time it takes to install chimney seals. 419/229-3015;

Structural renewal

The Monoform manhole lining system from Infra-structure Technologies Inc. (Infratech) rehabilitates brick and block manholes by creating a fully structural, monolithic, watertight concrete liner. After constructing a custom acrylonitrile butadiene styrene (ABS) form inside the manhole, contractors pour high-strength concrete, creating seamless walls and bases. The application of urethane sealants ensures watertight seals at all pipe connections. The system, which incorporates wall and reducer forms in various diameters and designs to fit most manholes, also rehabilitates lift station wet wells. 800/533-4244;

Complete spray unit

Graco/Gusmer mobile manhole sealant spraying rigs from Sprayroq Inc. are turnkey systems with everything necessary to be job-site-ready. Customized trailers or box trucks contain proportioning equipment, spray guns, heated hose on 300-foot capacity hangers, power components and material supply systems. Tools and equipment are organized for rapid accessibility. Color-coded restraints keep drums in place. Multiple trailer sizes and options available. 800/634-0504;

Concrete polymer paste

CPP Gel inflow sealant from Epoxytec prevents water from finding its way back through manholes after grouting active leaks. The fast-setting epoxy paste is moisture- and surface-tolerant, high-strength and hydrogen sulfide-resistant. It patches areas on and around chemical grout repairs to structurally seal and prevent further migration or corrosion. The paste is easy to use, often requiring just waterblasting or hand scrubbing to prepare the surface. The only necessary tools are two spatulas for mixing the A and B components, then applying the epoxy, which contains no volatile organic compounds. The paste bonds vertically and overhead. Available in 1-to-1 mix ratio (2-gallon kits or cartridges). 877/463-7699;

Spin cast repair

The bi-directional spin caster from AP/M Permaform renews deteriorated brick or precast manholes by high-speed, centrifugal casting of mortars or epoxies. One application seals and coats chimneys with a uniform, pre-selected thickness that can be inspected and verified at any point. The machine rehabilitates 10 to 15 manholes per day, minimizes confined-space entry, and is easy to use and maintain. 800/662-6465;

Robotic spray system

The portable TranSPOD robotic manhole spray application system from Remote Orbital Installations LLC operates from a trailer or truck. For off-road projects, the four-wheeled spray unit can be rolled out of the vehicle using manually deployed ramps and pushed or pulled to the work site.

Two mix guns in the spray head dispense material at 2,500 to 3,000 psi, while the head rotates at about 60 rpm (speeds from 0 to 300 rpm are possible). No chemicals or solvent flushing is necessary. A powered winch raises and lowers the spray unit, which can coat manholes up to 100 feet deep. A wireless remote controls major system functions. The robotic operation removes the hazards of confined-space entry, while delivering a consistent application. 608/845-0360;


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