Leak Detectable Geomembrane Liners and Method and Apparatus for Forming

A method of sealing a plurality of geomembrane panels together along adjacent edges, at least a first one of said panels having a conductive lower surface for testing said sealed panels for leaks, comprising the steps of:

• laying a second one of said panels on a surface;
• breaking the conductivity of the first panel bottom surface across a line adjacent the side of the second panel;
• heating the bottom surface of the first panel along the line;
• and
• pressing said first and second panels together along said line to heat seal the bottom of the first panel on top of the second panel.

A heat welder for securing edges of adjacent geomembrane liner panels together, said geomembrane liner panels having conductive bottom surfaces and being overlapped along their edges with a first one of said panels on top of a second one of said panels, said welder comprising:

• a welder body having forward and rear ends and defining horizontally oriented first and second slots with top and bottom walls extending between the welder body front and rear, wherein
• the first slot is open on one lateral side for receiving the first one of said panels,
• the second slot is below said first slot and open on the lateral side opposite the one side for receiving the overlapping edge of the second one of said panels, and
• said first and second slots merge at the body rear end;
• a drive for moving the welder body forward;
• a heating unit between said first and second slots and forward of said merged first and second slots, said heating unit defining a portion of a bottom wall of the first slot;
• and
• at least one projection extending partially into said first slot for engaging the conductive bottom surface of the first one of said panels to interrupt the conductive bottom surface along a line as it passes the projection;
• wherein said merged first and second slots press together first and second liner panels to heat weld the first and second liner panels together along the line of the interrupted conductive bottom surface.

A heating unit for use with a heat welder for securing overlapping edges of adjacent geomembrane liner panels together, said welder including upper and lower slots guiding the overlapping edges of adjacent liner panels toward a merged slot in which said adjacent panels are heat welded, said heating unit comprising:

• a wedge mountable in a heat welder between said first and second slots whereby said wedge
• defines part of an upper wall of the lower slot and the lower wall of the upper slot, and
• said defined upper and lower walls taper together to a paint adjacent the merged slot;
• and
• at least one projection extending from the wedge defined lower wall of the upper slot sufficiently to interrupt a bottom portion of a liner panel passing through the upper slot over the projection while still maintaining the overall structural integrity of the panel.