SITE INFORMATION AND CORRESPONDENCE_FILE 1

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Mr. Edward C. Ralston Unocal Corporation October 25, 1995 Page 2 The initial water measurement in the diesel tank was 114 inches. After puncture, water stabilized at 81.75 inches in the tank. Using these measurements, a volume of 2,760 gallons of released water was calculated. Utilizing the analytical results (61,000µg1L diesel)and the volume of water released, a calculated volume of 0.17 gallons of diesel fuel was released. The calculations of the volume of water released and corresponding diesel fuel are presented in Enclosure B. Date of Release The date of the release was October 23, 1995. Date the Release was Discovered The release at Unocal Service Station No. 5886 was discovered in the field on October 23, 1995, during the installation of shoring around the underground storage tanks. During the installation of the shoring, an approximate 12 inch hole was punctured in the top, east end of the diesel tank (Tank T3). Water leaked from the tank until it was below the punctured area. The tank was a 12,000 gallon, 9.5 foot (114 inches) diameter fiberglass tank. It was filled with ballast water to 114 inches and leaked out to a final level of 81.75 inches (verbal communication, Ron Rowe). Date Release was Stopped The release of hydrocarbons in the ballast water in the diesel tank terminated on October 23, 1995. Description of Actions Taken to Stop the Release Following the puncture of the tank, approximately 2,760 gallons of ballast water leaked into the tank cavity. The release stopped once water got to the bottom of the puncture. Water remaining in the tank was then pumped on October 23, 1995, into an above ground storage tank prior to removal of the tanks on October 25, 1995. New tanks are scheduled for installation on October 27, 1995. Description of Corrective Actions Delta submitted a Work Plan for Underground Storage Tank Removal, dated October 16, 1995. This work plan proposes the removal of the three existing 12,000 gallon fiberglass tanks, the collection of soil samples, the removal of ground water for construction purposes, and the removal of soil to enlarge the tank cavity to hold the new, larger tanks. Following the completion of the tank replacement and the on-site assessment, a report will be prepared outlining the activities performed at the site, all analytical results, and Delta's findings and conclusions. It is Delta's understanding that the ballast water was removed from the tanks on October 23 and 24, 1995, prior to the removal of the tanks. Following the removal of the tanks on October 25, 1995, soil samples were collected from the sidewalls of the tank excavation and beneath the former tanks. Samples were submitted for chemical analyses of TPH as gasoline, TPH as diesel, benzene, toluene, ethylbenzene, and total xylenes (BTEC. Samples have been submitted to Sequoia Analytical laboratory in Sacramento, California, however analytical results have not been received to date.