Abstract: The present invention is directed to the control of the movement of slip liners in grouting operations through the use of inflatable grouting bags and to the control of bulkhead sealing in slip liner grouting operations.

Abstract: Porous pipe having a porosity which varies continuously and controllably with length is produced by extruding a mixture of particles of prevulcanized elastomer such as reclaimed crumb rubber and a thermoplastic binder such as polyethylene with all parameters controlled except for die temperature of pull-off rate. By gradually varying temperature or pull-off rate during extrusion, the porosity of the pipe gradually changes. The leak rate can be controlled in a manner to produce a length of porous pipe in which the leak rate is constant as the pressure drops over the length of the pipe.