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<br /> <br />3. Test welds should always be prepared and tested before seaming in order to gauge <br />appropriate welding conditions. (Example: Welding machine temperatures should <br />be set higher and welding rates reduced). <br />3.3.E Trial Seams <br />Trial seams shall be made on fragment pieces of geomembrane liner to verify that <br />seaming conditions are adequate. Such trial seams shall be made at the beginning of each <br />seaming period (start of day, midday, and anytime equipment is turned off and allowed to <br />cool down) for each seaming appazatus used. Trial seams shall be made under the same <br />conditions as the actual seams (see Figure 6, example of Pre-Weld Qualification form). <br />The trial seam sample shall be approximately 3 fzet (LO m) long by 1 feet (0.3 m) wide <br />(after seaming) with the seam centered lengthwise. Seam overlap shall be nominally g <br />inches; 3 inches minimum. <br />Two adjoining specimens each I inch (25 mm) wide, shall be cut from the trial seam <br />sample by the installer. The specimens shall be tested respectively in shear and peel <br />using a field tensiometer, and they should not fail in the seam. It the additional specimen <br />fails, the entire operation shall be repeated. If the additional specimen fails, the seaming <br />apparatus and seamer shall not be accepted and shall not be used for seaming until the <br />deficiencies are corrected and two consecutive successful full trial welds are achieved. <br />3.3.6 General Seaming Procedure <br />Unless otheRVise specified, the general seaming procedure used by [LPI shall be as <br />follows- <br />The rolls of membrane shall be overlapped by a minimum of four (4) inches (100 <br />mm) for fusion welding and three (3) inches (7~ mm) for extrusion welding. <br />"Fishmouths" or wrinkles at the seam overlaps shall be cut along the ridge of the <br />wrinkle in order to achieve a flat overlap. The cut "tishmouths" or wrinkles shall <br />be seamed and any portion where the overlap is inadequate shall be then patched <br />with an oval or round patch of the same geomembrane extending a minimum 6 <br />inches beyond the cut in all directions. <br />Seaming shall extend up the panels and well into the anchor trench. <br />All cross seams aze to be extrusion welded where they intersect. The top flap of <br />membrane is removed in the azea to be extrusion welded and the weld area is <br />ground parallel to the seam prior to welding. <br />19 <br />