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seam defects and repairs. Nondestructive testing procedures are described below: • For welds tested by vacuum method the weld is placed under suction utilizing a vacuum box constructed with rigid sides, a transparent top for viewing the seams, a neoprene rubber gasket attached to the bottom of the rigid sides,a vacuum gauge on the inside,and a valve assembly attached to a vacuum hose connection. The box is placed over a seam section that has been thoroughly saturated with a soapy water solution(1 oz. soap to 1 gallon water). The rubber gasket on the bottom of the box must fit snugly against the soaped seam section of the panel, to ensure a leak-tight seal. A vacuum pump is energized and the vacuum box pressure reduced to approximately 5-psi gauge. Any pinholes,porosity or non-bonded areas are detected by the appearance of soap bubbles in the vicinity of the defect. Dwell time must not be less than 10 seconds. • Air pressure testing is used to test double seams that have enclosed air space between them. Both ends of the air channel must be sealed. A pressure feed device, usually a needle equipped with a pressure gauge, is inserted into one end of the channel. Air is then pumped into the channel to a minimum pressure of 30 psi or 1/2 psi per mil of geomembrane thickness,whichever is greater. A two-minute relaxing period is allowed for the pressure to stabilize. The air chamber must sustain the pressure for a further 5 minutes without losing more than 2 psi. Following a passed pressure test,the opposite end of the tested seam must be punctured to release the air. The pressure gauge must return to zero, if not, a blockage is likely in the seam channel. Locate the blockage and test the seam on both sides of the blockage. The penetration holes must be sealed after testing. During nondestructive testing,the QA/QC Inspector will: • Review Specifications regarding test procedures. • Verify that equipment operators are fully trained and qualified to perform their work. • Verify that test equipment meets Specifications. • Verify the entire length of each seam is tested in accordance with the Specifications. • Observe all continuity testing and record results on the panel/seam log, and the panel layout drawing. • Verify that all testing is completed in accordance with the Specifications. • Identify any failed areas,by marking the area with a waterproof marker compatible with Page 26