Traditional repair methods are time consuming and expensive, involving the search for the leak site, and the use of open excavations to expose and encapsulate or inject each leaking joint.

Foster-Miller has developed a prototype remotely operated system that is capable of internal repair of multiple joints from a single excavation that requires a crew of only two people. The joint sealant system consists of both a custom sealant and applicator device that have been designed to function within the unique environment found in old cast iron mains.  This environment contains high levels of corrosion debris, degraded or non-porous jute, and other contaminants that adversely affect the performance of existing sealants and application systems.

The Foster-Miller sealing technique involves filling the gap between the end of the spigot and the heel of the bell, thereby bridging this region. The sealant is a good gap filler and has good wetting and adhesion properties onto corroded cast iron.

The basic delivery platform is a hollow "snake" and rotary applicator head.  A small "air" motor that is operated using natural gas powers the rotary head, and the sealant is applied to the joint through this head. The system is inserted into the main through a commercially available entry saddle. The snake and rotary head are positioned at the centerline of the main by a collapsible spring centralizer, and then the snake is propelled manually into and out of the main from the surface. The snake contains tubing for delivery of the sealant and a fiberscope, which allows the operator to inspect the main, locate the joints, and observe the sealing operation. The operator's control station consists of gas and sealant flow controls, metering equipment, and video display.

A prototype system has been developed and demonstrated, and Foster-Miller expects to build and evaluate additional systems.

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