Soil contamination from waste impoundments or ponds, leakage of buried waste, or dumping of waste directly onto the ground, has heretofore been recognized as a serious problem both in this country and abroad. Many techniques have been proposed for addressing this problem, ranging from removal of contaminated soil for redisposal or treatment, to in-situ treatment by chemical reaction in an effort to neutralize contaminants or encase the contaminated soil in solid concrete or the like. One particular method for in-situ-treatment of contaminated soil heretofore proposed in the art involves driving one or more augers into the earth while simultaneously injecting treatment fluid through nozzles in or associated with the auger drill bits. The auger is carried by apparatus suitable for movement between successive drill positions, so that holes are drilled and soil is treated in a pattern that ultimately includes an entire contaminated field. While this technique and theory have the significant advantages of economy, and of not requiring removal of contaminated soil, with consequent danger of dispersing gaseous contaminants and dust, these theoretical advantages have not heretofore been realized in fact.
One disadvantage of auger-type devices heretofore proposed lies in the small surface area and depth that can be treated in a single drilling operation. In an effort to increase coverage area and treatment efficiency, it has been proposed to provide multiple parallel augers rotated in an interlocking pattern. However, such multiple-auger systems still only cover a surface area of up to about thirty square feet in each penetration, and typically have a maximum penetration depth of about thirty-five feet. Furthermore, a rock or other obstruction can become wedged between the auger blades, locking the drill system and causing significant downtime for removal and repair.
It is therefore a general object of the present invention to provide an apparatus and method for contaminated soil treatment that obtain the advantages of auger-type techniques heretofore theorized but not in fact obtained in the art. A more specific object of the invention is to provide an apparatus and method of the described character that are capable of enhanced depth of soil penetration as compared with techniques heretofore proposed, that cover greater surface area on each drilling operation, and that thus may be operated more efficiently than techniques heretofore proposed. Another and related object of the invention is to provide a single-bit apparatus of the described character in which the drill bit is driven with enhanced power as compared with prior art devices, thereby enabling both greater surface area coverage and greater depth of soil penetration. A further object of the present invention is to provide an apparatus and method that are adapted for enhanced control of fluid injection for soil treatment for obtaining greater drilling speed, increased treatment efficiency and more efficient treatment control than prior art techniques of a similar character.