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