Method of forming a subterranean water barrier and a plow for use therewith

A method of forming a continuous flexible subterranean water barrier of congealed thermoplastic material, said barrier composed of a plurality of separately formed barriers having finite dimensions, each separate barrier in transverse section having a central portion continuous with lateral side portions wherein each side portion is inclined relative to said central portion and terminate in a lateral edge at an elevation different from the elevation of said central portion, comprising:

• I. forming a first barrier as defined above at a preselected depth beneath the soil surface by the steps of:
• a. moving a plow having a cavity therein through the soil to continuously displace the soil upwardly at said depth thereby separating the soil into an upper portion supported by the plow and an exposed lower portion;
• b. concurrently introducing said thermoplastic material into the cavity of said plow to fill it up without leaving any void portion;
• c. ironing said thermoplastic material so as to spread same over uniformly in the transverse direction of said plow by passing said thermoplastic material through a restricted outlet from said plow so as to form a congealing coating of said material, said restricted outlet being defined between a rear bottom surface of said plow and the lower exposed soil portion and being located at the rear end portion of said plow;
• and
• d. continuously covering said coating by free flow of said supported soil simultaneously with releasing an excess pressure on said thermoplastic material within said plow which exceeds a balanced pressure created by a soil pressure at the point of tail end of said plow and a pressure of said thermoplastic material inside said plow thereby preventing an excess outflow of said material from said plow, whereby said first barrier of uniform thickness is formed;
• and
• Ii. forming an adjoining barrier in a path parallel to the first path and at the preselected depth to engage said first barrier by repeating the steps employed in forming the first barrier and including continuously intersecting the adjacent lateral side portion of said first barrier with a new lateral side portion of said adjoining barrier, thus joining said first barrier and said adjoining barrier to provide a continuous water barrier laterally and longitudinally by separately formed barriers.