Abstract: An apparatus for repairing leaks in underground pipe which comprises a carriage movable axially along the pipe, a flexible and stretchable tubular cover sheet surrounding a portion of the carriage, a plurality of power driven back-up plates supported by the carriage and expandable radially to press the sheet into intimate contact with the internal wall surface of the pipe, and retractable radially for separating the sheet from the pipe wall, and a conduit inside the cover sheet for delivering grout radially outwardly through the cover sheet.

Abstract: A method of repairing leaks in underground sewer pipe which includes the steps of closing the pipe at an upstream and a downstream position forming an enclosed section, filling the enclosed section with grout under pressure from a source and causing said grout to ooze through the leaks, replacing the grout in the enclosed section with a non-hardening liquid under pressure which prevents the grout which has oozed through the leaks from passing back into the enclosed section, and removing the non-hardening liquid from the enclosed section after the grout has hardened and sealed the leaks.