It is conventional to provide a substantially horizontal, underground passageway for the accommodation of a conduit having a cylindrical wall provided with openings through which fluids such as water or other liquids may pass to enable earth above the passageway to be dewatered or drained. Examples of apparatus for accomplishing this objective are disclosed in Wagner et al U.S. Pat. No. 4,543,013, issued Sep. 24, 1985 and Cherrington et al U.S. Pat. No. 4,679,637 issued Jul. 14, 1987.
It also is conventional to install in an underground passageway, after the formation thereof, a conduit composed of a plurality of pipe sections at least some of which have a wall provided with openings through which water or other fluids may pass. Examples of such conduit-forming pipe sections are disclosed in Lange U.S. Pat. No. 6,073,659 issued Jun. 13, 2000 and Bloomfield et al U.S. Pat. No. 6,561,732 issued May 13, 2003.
The disclosures of the above identified patents are incorporated herein by reference.
The underground passageway conventionally is formed by a drill member secured at one end of a rotatable drill stem composed of a string of tubular rod sections joined to one another in such manner as to enable all of such sections and the drill member to be rotated simultaneously and moved linearly in a direction to form the underground passageway. Following forming of the passageway the drill member conventionally will occupy an accessible position enabling it to be removed from the drill stem and the drill stem then to be coupled to a reamer which can be drawn rearwardly through the passageway so as to enlarge the passageway. The reamer may be coupled to one end of a string of conduit-forming pipe sections which will be drawn through the reamed passageway in response to rearward movement of the drill stem and reamer. When the pipe string reaches the point at which the forming of the passageway commenced, it may be detached from the drill stem and coupled to a pump so as to enable whatever liquid is in the underground conduit to be withdrawn therefrom. In this manner a swampy area above the conduit may be drained. Further, contamination which may result from the discharge of toxic materials to land areas may be drained from such areas. In addition, fluids containing bioremedial substances may be pumped into the conduit and discharged through the openings thereof into the area encircling the conduit so as to detoxify such area.
There are several objectionable characteristics of the conventional apparatus referred to above. Among them are the necessity of making at least two passes underground, one of which is in the initial formation of the passageway and the other of which is the reaming of the passageway to an appropriate size to accommodate conduit and installing the conduit. Another objectionable characteristic is the difficulty of disconnecting the drill stem from the drill member or other device rotated by the drill stem, including in some instances the necessity of extending the drill member to the surface or excavating a pit to obtain access to the drill member in its underground position. A further objectionable characteristic of conventional apparatus is that the openings in the conduit may not be of such size as to accommodate fluids of different viscosities with optimum flow rates.
A principal object of the invention is to provide methods and apparatus which overcome the objections referred to above.