Abstract: An hydraulic device for forming a cavity in a borehole. The device includes generally the following modular sections: a hub section for connection to a drill pipe; hydromonitor (cutting nozzle); hydroelevator (eductor); and drill bit box. Through each section, except the drill bit box, extends first and second concentric pipelines for delivering fluid into the device and directing slurry out of the device. Only the drill pipe extends to the surface to receive standard well blowout prevention equipment. The second pipeline releases slurry into a casing which channels, in cooperation with an upper portion of the first pipeline and the drill pipe, the slurry to the surface. The hydromonitor includes a nozzle which is hydraulically associated with the first pipeline, and extends through the second pipeline, for delivering fluid into the borehole to form the cavity. The eductor pulls spent cutting fluid, coal fines, etc., out of the cavity as the slurry.