The ATHSP medium dual wall heat shrink tubing was especially developed for groundwater applications. This high shrink ratio tubing (4 to 1) is supplied with an inner wall of adhesive that melts and flows when heat is applied. The tubing shrinks rapidly to a skin tight fit, forcing the the melted adhesive to flow and cover the substrate. The extra large amount of adhesive flows out of the ends of the splice, beading at the ends and ensuring a water tight connection. Upon cooling, the adhesive solidifies, forming a permanent, non-drying, flexible and waterproof barrier.