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• Verify that seam grinding is completed less than 1 hour before seam welding, and the upper sheet is beveled (extrusion welding only). • Verify that ambient temperature measured 6-inches above the geomembrane surface is between 400 and 1040 Fahrenheit. • Verify that ends of extrusion welds that are more than 5 minutes old, are ground to expose new material before restarting a weld. • Verify that contact surfaces of the panels are clean, and free of dust, grease, dirt, debris and moisture before welding. • Verify that welds are free of dust, rocks and other debris. • Verify that cross seams are ground to a smooth incline before welding(fusion welding only). • Verify that all seams are overlapped a minimum of 3 inches or in accordance with manufacturer's recommendations, whichever is more stringent. • Verify that solvents or adhesives are not present in the seam area. • Verify that procedures used to temporarily hold the panels together do not damage the panels and do not preclude CQA testing. • Verify that strips of geomembrane, wide enough and long enough to protect the hot wedge welder from running on the subgrade is placed below the geomembrane. These strips may be as long as the seam itself or shorter and moved with the seaming equipment. If necessary,a firm material such as a flat board or similar hard surface may be placed directly under the weld overlap to achieve firm support. • Verify that panels are being welded in accordance with the Construction Drawings and Specifications. • Verify that there is no free moisture in the weld area. • Measure surface temperature of the panels every 2 hours. 4.2.4 Seam Testing Nondestructive Seam Testing. The purpose of nondestructive geomembrane testing is to detect discontinuities or holes in the seams. Nondestructive geomembrane tests include vacuum and air pressure testing. Nondestructive testing must be performed over the entire length of the seam. Page 30