Shrinkage of GCL panels in composite liners left exposed to solar radiation (i.e with no cover soil/ ballast) has resulted in significant separation between initially overlapped panels in a number of field cases reported in the literature. Separations between panels of 200-450mm, and in one case of 1200mm, have been reported. In an attempt to reduce the risk of panel separation, a technique of heat-tacking the overlap between adjacent panels of GCL was employed at a leach pad in Arizona. Exhumation of six mid-slope locations in the field indicated that there was no opening of the panel over-laps at the heat-tacked seams after more than 60 days exposure. This paper reports the results of a laboratory pan shrinkage test as well as tensile tests on seams prepared at this field site. The shrinkage test generated a maximum shrinkage of about 17% in the GCL adjacent to the heat-tacked seam after 40 wet-dry cycles. The same wet-dry cycles generated a tensile stress in the seam corresponding to a 13% tensile strain in the GCL adjacent to the seam. The heattacked seam readily withstood this tensile force. The tensile strength of the samples tested was 10-14kN/m. The tensile strength of the sample used in the shrinkage test was controlled by the manufactured groove in the GCL adjacent to the seam and not the seam itself Although additional testing is required to confirm the findings from the tests reported herein, it would appear that the technique of heat-tacking the overlap between GCLs has potential for reducing the risk of shrinkage induced separation at GCL panel overlaps.