Abstract: In order to consolidate soil, a hole is drilled therein by advancing downwardly through the soil a rotary percussive drill bit disposed at the end of a drill string. Water is pressurized at the ground surface and is conducted to actuate a hydraulically driven down-the-hole hammer disposed above the drill bit. While vertically retracting and rotating the drill string, grout, which is pressurized at the ground surface, is conducted downwardly through the drill string and ejected laterally outwardly through a lateral opening in the drill string to produce a console of mixed soil and grout surrounding the hole. The water and grout are pressurized in respective chambers of a pump.