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MANAGER and CERTIFYING ENGINEER may require CONTRACTOR to test up to as much as <br />twenty percent (20%) of factory fusion welds (non-destructive air pressure test) in the field to verify <br />• factory test results. Additional testing at CONTRACTOR'S expense will be required if failed tests aze <br />obtained in the field. <br />3.07 FIELD SEAMS: <br />A. Seam Layout <br />1. Seams shall be oriented parallel to the line of maximum slope, i.e., oriented down, <br />not across the slope. In corners and odd-shaped geometric locations, the number of <br />field seams shall be minimized. <br />2. No horizontal or base T-seam or tie-in seams shall be closer than five (5) feet from <br />the toe of the slope. Seams shall be aligned to prevent wrinkles and "fishmouths". If <br />a fishmouth or wrinkle is found, it shall be relieved and capped. <br />3. Panels of geomembrane will have sufficient overlap provided to allow peel tests to be <br />performed on the seam. <br />B. Seaming Method <br />1. The procedure used to temporarily bond adjacent panels together shall not damage <br />the geomembrane; in particular, the temperature of hot air at the nozzle of any spot <br />welding appazatus shall be controlled such that the geomembrane is not damaged. <br />2. CONTRACTOR shall use double fusion welding as primary method of seaming <br />adjacent field panels. <br />a. For cross seam tees associated with fusion welding, CONTRACTOR shall <br />patch panel intersections consisting of 3 or more panels and extrusion weld <br />to a minimum distance of 4 inches on each side of patch. The edge of the <br />sheet shall be ground to a 45° angle prior to welding. <br />b. Place a protective layer, e.g., insulting plate or fabric, beneath hot welding <br />apparatus after usage. <br />c. When subgrade conditions dictate, use a moveable protective layer directly <br />below each overlap of geomembrane that is to be seamed to prevent buildup <br />of moisture between sheets and prevent debris from collecting around <br />pressure rollers. <br />d. Remove seaming sheets and excess geomembrane trimmed to provide <br />requved overlap. <br />3. Use conventional extrusion welding as a secondary method for seaming between <br />adjacent panels and as a primary method of welding for detail and repair work. <br />a. Purge heat-degraded extrudate from barrel of extruder under dte foI[owing <br />conditions: <br />1. Prior to beginning a seam. <br />2. Whenever extruder has been inactive. <br />Section 02776 Page 14 of 20 October 25, 2000 <br />Geomembtane Golder Associates Revision 8 <br />1:\00\2203W 400\CERiREP0802\APPENDSAPPE\993-2099021)61RH.DOC <br />