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r r NINIIAL Section 4 Supplemental Observations To supplement the information presented in the previous section, the author had the opportunity to observe another lining installation operation with the IECC product in Colorado. In addition, a full report of an interior ultrasonic integrity inspection conducted in California was obtained and reviewed. Each of these is discussed here. 4.1 Colorado Tank Lining Observations On July 19 and 20, 1995, the author had the opportunity of observing a tank lining operation with the IECC EC 125.lining material in the Denver, Colorado area. Specifically, the observations occurred at a Bradley Self-Serve station at 3485 West 72nd Street in Westminster, Colorado, a suburb north of Denver. The station has six underground tanks, three of which were to be lined and three were to be taken out of service and removed. The lining work was being performed by Rockey's, Inc., but by a crew out of Colorado Springs, not Topeka. We had the opportunity during the course of four visits to the site (while conducting other business in the Denver area) to observe almost all facets of the operation. To avoid repetition, only our observations that supplement those.in Section 3 will be given here. After pumping out a tank, purging was begun using method 2.4.3.2 of API 1631. A brass air-diffusing pipe was inserted into the fill opening, resting on the tank bottom and grounded to the opening. The pipe had four rows of small holes running its length for introducing air into the tank. Compressed air was delivered to the pipe through a fitting with a pressure regulating valve and gauge, to maintain no more than 5 psi of pressure. Figure 4 shows the diffused-air blower setup. Vapors were vented from the tank's vent pipe. An MSA combustible gas indicator was used to monitor the gas being vented. When the reading dropped below 20% of the lower flammable limit (LFL), purging was continued and a small hole was drilled into the tank using an air-driven drill and lubricating oil. Then a long probe was inserted into the hole and monitoring of the atmosphere inside the tank was conducted, as purging was still being continued. This is shown in Figure 5. Finally, after the reading dropped below 10% of the LFL, three more holes were drilled in the tank to outline the comers of the manway opening. Then, while continuing to purge, an air-driven power saw was used, with copious amounts of lubricating oil, to cut between the holes. As the last cut was being completed, another crew member supported the cut plate and lifted it out. MRI-APPSOM4069-PR 8