Grouting can reduce or eliminate inflow and infiltration of sewer lines and manholes by stabilizing and sealing defects and leaky joints together with the adjacent soil. This is most effective where the defects are not severe and the surrounding soil is stable enough to retain the grout. Grout can be applied over a large area such as manhole to manhole or at specific points along the mainline or at lateral joints. Localized grouting involves the use of inflatable packers, sized to the section of the pipe or service connection, to isolate the joint or defect to be grouted from the rest of the sewer system – allowing the controlled application of grout only to the part of the sewer sealed off by the packer. After cleaning of the pipe, the packer is pulled into position over a joint or connection containing defects. The packer is then inflated – sealing off the area for testing and potential grouting. Once the defect is isolated by the packer, a pressure test is conducted. If the joint or defect maintains pressure, then there is no need for the grouting operation and the packer is moved to the next location. If pressure loss occurs, then the joint or defect is grouted. Hoses feed grout to the packer and the injection ports located in the area of the packer isolated by the packer and the pipe wall inject grout under pressure into the packer/pipe cavity, defects and the soil outside the pipe surrounding the defects. The principal sealing of the defect is accomplished by the grouting of the soil outside the defect rather than the plugging of the defect in the pipe wall itself. There are a variety of chemical grouts used for grouting of pipe joints and sewer connections. The grout should be compatible with the pipe materials and soil conditions surrounding the defect. For leak sealing in pipes, common grouts typically set into a gel binding together and sealing the soil matrix. Other grout formulations (such as urethane grouts) are available for particular applications where the gel type grouts are not suitable.
Also see "Joint Grouting".