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to preclude wind effects. No equipment is allowed to commence welding on the liner until field test samples made by that equipment have passed a welding test. In performing hot wedge welding, the welding apparatuses shall be automated vehicular mounted ' devices equipped with gauges giving applicable temperatures and pressures. All cross seams shall be capped with a minimum 12-inch wide patch of identical geomembrane. A smooth insulating plate or fabric shall be placed beneath the hot welding apparatus after usage. The Contractor shall protect against moisture buildup between sheets. If welding across cross seams, field seam tests shall be conducted at least every two hours, otherwise tests shall be conducted prior to start of work and once at mid-day. No equipment is allowed to commence welding on the liner until the field test sample made by that equipment has passed a weld test. 4.2.9.b Pre-Welding_Oualification ' When the temperature is below 50°F, the Contractor shall provide preheating by a hot air device. ' Field seam tests shall be conducted on pieces of geomembrane liner to verify adequate seaming conditions at the following frequency: - At beginning of the seaming period; - At least once for each four hours of seaming; - At the Quality Assurance Engineer's discretion; - For each seaming apparatus used; and - At least once before each shift for each welding person performing seaming. ' Test seams shall be made in the areas of seaming and in contact with subgrade or geoteztile (to simulate the condition in the work area of the geomembrane to be seamed). The seam sample 1 should be at least 42 inches long and 12 inches wide with seam centered lengthwise. Two 1-inch wide specimens shall be cut near each end of test seam. Specimens shall be quanti4ltively tested for peel adhesion and bonded seam strength (shear). A test seam passes when both specimens show: ' - The break is a film tear bond (FTB); or ' -n-