Where suitable internal repairs are not possible, it may be necessary to access the pipe from the surface to complete a repair, install a valve, etc., e.g. in the case for water or gas mains providing service to property owners along a public right-of-way. Access to a main at reasonable depth can be provided using small diameter holes from the surface – created by “soft” excavation techniques using vacuum excavation. These holes may be 0.5 m diameter or less and the soil excavation techniques may use air or water lances to loosen the soil prior to vacuuming it out of the hole. When combined with careful road pavement cutting techniques (such as the “keyhole” technology pioneered by the gas industry), the damage to a road pavement and the disruption to traffic is minimized. Special tooling to allow pipe sealing, pipe cutting, connection or valve installation from the surface in such restricted with excavations has also been developed.
Vacuum excavation systems combine pressurized jetting and suction equipment to support a number of construction and trenchless applications. These systems come in a wide variety of sizes. They may be self propelled or mounted on trailers. The basic components of a vacuum excavation system include a slurry or debris tank capable of storing spoils until they are discharged off-site; a suction hose and pump to vacuum spoils from the earth or from pits and reservoirs to a slurry tank; and an engine to power the system components. If the system includes hydro excavation capabilities, water tanks, pumps, water lines, and jetting tools such as wands and water lances are also needed.