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1 <br />- Use only soft bristle brush after grinding if brushing required, wire brushes shall not be <br />used; <br />- Cut wrinkles and "fishmouths" along ridges; <br />- Overlap and seam wrinkles and fishmouths; <br />- Patch wrinkles and fishmouths where overlap is less than 3 inches; <br />' - Use a firm, dry substrate (piece of geomembrane or other material) directly under seam <br />overlaps where the subgrade is soft; and <br />- Use plywood or other firm material under seam overlaps when welding over the anchor <br />trench. <br />4.2.9.5 Geomembrane Seamin~Aoparatuses <br />' At least one spare operable seaming apparatus shall be maintained for each three seaming teams. <br />The Contractor shall place a protective fabric or a piece of geomembrane bene8th hot welding <br />apparatus when resting the apparatus on the geomembrane lining. The Contractor shall provide <br />a protective lining and splash pad large enough to catch spilled fuel under any electric generators <br />or fuel powered equipment when it is located on the liner. All sharp parts protruding from any <br />' equipment shall be covered prior to placement on the geomembrane. The welding apparatus shall <br />' be equipped with gauges giving temperatures in the apparatus and at the nozzle. <br />For extrusion welding, the Contractor shall purge the welding apparatus of heat-degraded <br />' exwdate for at least 1 minute before welding if the ezwder is stopped for lodger than three <br />minutes. All purged extrudate shall be disposed of outside the geomembrane covered area. The <br />1 Contractor shall avoid stop-start welding. The Contractor shall grind existing welds two inches <br />from the point of stoppage or two inches on each side of leaks before welding. Leaks evident <br />in extrusion welds will require a minimum l2-inch diameter patch of the same material. The <br />Contractor sha(1 restart welds two inches from each side of leaks. The Contractor shall restart <br />welding two inches back from the point of stoppage. No equipment is allowed to commence <br />welding on the liner until the field test sample, made by that equipment, passes the weld test. <br />' For interface extrudate welding, the Contractor shall test and set the "hot arr system" using scrap <br />material at least once each day prior to commencing seaming and shall adjust the hot air velocity <br />' -I6 <br /> <br />