Method and apparatus for installment of underground utilities

An apparatus for drilling an underground passageway comprising:

• (a) a bendable, hollow drill string which has a front end and a back end and which when maintained straight defines a straight, longitudinal axis;
• (b) a nozzle assembly connected to the front end of said drill string and including a nozzle body having at least one jet orifice which is located at the front end of the assembly and which defines a jet flow axis disposed at an acute angle with respect to the longitudinal axis of said drill string when the latter is straight, said nozzle body having one outer side surface thereof which extends from the front of the nozzle assembly rearwardly to a limited extent in a fixed direction at an acute angle with the longitudinal axis of said drill string when the latter is straight, said outer side surface of said nozzle body being disposed above said orifice when said jet flow axis is angled downward;
• (c) means for supplying high pressure fluid through said drill string and to said orifice for producing a fluid jet out of said orifice in the direction of said jet flow axis, and thereby at an acute angle with respect to said longitudinal axis;
• (d) means for intermittently rotating said drill string and said nozzle assembly about the longitudinal axis of said drill string whereby to cause said fluid jet and said outer side surface of said nozzle body to rotate about said longitudinal axis;
• and
• (e) means for pushing said drill string and nozzle body in the forward direction in the presence of said fluid jet so as to cause the drill string and nozzle assembly including said angled fluid jet and said outer side surface of said nozzle body to move along a straight line path when said fluid jet is simultaneously rotated and so as to cause the drill string and nozzle assembly including said angled fluid jet and outer side surface to turn in the direction of said jet flow axis when said fluid jet is not rotating whereby said outer side surface because of its location relative to said orifice lies outside the turn as said nozzle assembly is caused to make a turn.