Grouting can reduce or eliminate inflow and infiltration of sewer lines and manholes by stabilizing and sealing the defect and the adjacent soil where the defect is 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. Epoxy resin or mortar is used in grouting localized defects. A chemical mix is used for flood grouting of a large section of sewer mains and laterals.
The process of grouting requires that the pipe to be grouted is cleaned. In the case of flood grouting of large sections of sewer mains, the main is cleaned and desilted by flushing with a high pressure water jet. The length of the main to be grouted and all laterals are sealed by pneumatic rubber plugs. The sewer is filled with the first of two chemical solutions from a manhole or access point. Hydrostatic pressure forces the solution into the soil surrounding the sewer at defect points. The first solution is pumped out leaving the defect and nearby soil saturated with the solution.
The sewer section is refilled with a second chemical solution, which reacts with the first quickly forming a concrete-like matrix that binds the soil and consolidates the ground around the defects. After the completion of the reaction of the two chemical solutions, the second solution is pumped out. The sewer is flushed, the seals removed, and sewer section returned to service.