A ground drill system 10 has a drill string 14 which forms first and second mutually isolated fluid paths 16 and 18 respectively. The drill string 14 has an up hole end 20 s coupled to a dual circulation rotation head 22 and a down hole end 24 which is coupled to a drilling tool 12. The drilling tool 12 is operated by the flow of fluid delivered through the first flow path 16. A second fluid outlet 26 is provided intermediate the up hole end 20 and the drilling tool 12. The outlet 26 is in fluid communication with the second fluid flow path 18 and located a constant or fixed distance from the drilling toll 10 12. The second fluid outlet 26 discharges a flushing fluid flowing through the flushing flow path 18 into a hole being drilled by the drilling system 10. The rotation head 22 provides torque to the drill string 14 and thus the drilling tool 12. 4S~4O3 I c~i~etrs) F -$ .U 2 54' ~"'0 Q-J ... ...... 5 6
