One of our installers came across a very unique situation where there was no way to attach the existing pond liner around the top of this boulder and effectively get it to seal.  We devised a plan to double fold the liner underneath a piece of stainless steel strap that then sandwiched the liner to the rock.  The stainless steel strap was then bolted firmly to the boulder using stainless steel anchors.  Once everything was set, Pond Shield was applied to the stainless steel and a bridge using both Pond Shield and fiberglass mat was applied.  The bridge covered both the stainless steel and overlapped onto the boulder by an inch or so.