Patent ID: 7637696

Claim:
An underwater trenching apparatus, comprising: an elongated boom assembly having a proximate end secured to a propelling vehicle; a trenching unit secured to a distal end of the boom assembly, said trenching unit being adapted for movement between an above-water position and an underwater position, said trenching unit having a means for delivering air and water under pressure to a trench location underwater to disturb underwater formation and for moving the disturbed formation away from the trench location, said trenching unit comprising at least one sparge assembly, said at least one sparge assembly comprising a sparge conduit provided with a plurality of jetting nozzles, an elongated tubular member secured adjacent said sparge conduit, and an airlift insert mounted in the tubular member for creating turbulence inside the tubular member and facilitating movement of the formation through said tubular member, said airlift insert comprises a tubular body having a flared inlet opening and a reduced size main body, and wherein a plurality of openings is formed in said main body for receiving air from said means for delivering pressurized air; and a means for delivering pressurized air to the tubular member, said means for delivering pressurized air being operationally connected to said airlift insert.