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MOBIL INSPECTION -2- 14 JULY 1.987 <br /> I was told that two underground tanks at this site were recently <br /> removed under the direction of Mardo Kaprealian. The excavation at <br /> the corner of the site near the road had formerly contained a 280 <br /> gallon vapor drop out tank. This was the location where the black <br /> oil-like substance was observed on an earlier visit. I was told <br /> that vapor from the load rack is pumped to the Shell Bulk <br /> Distribution Facility to the west via underground pipes where it is <br /> condensed. The condensed liquid is recovered in the vapor drop-out <br /> tank. The excavation was open the day I was there, and a new 500 <br /> gallon fiberglass tank had been emplaced. No soil contamination was <br /> visible, but the excavation was partially backfilled. Mr. <br /> Kaprealian said that soil r.enoved from under the tank was <br /> contaminated, and samples of soil and water had been taken for <br /> analysis. He is preparing a report that will include the analyses, <br /> and a workplan which will propose a method to determine the extent <br /> of contamination at this site. He said the workplan will include <br /> proposed locations for three monitoring wells on the site. <br /> SUMMARY <br /> The Mobil site appears well-maintained on the surface. Removal of <br /> the outlet pipe from the underground tank would prevent any future <br /> discharges of polluted water to the ground surface from this pipe. <br /> The source of the dark oily substance observed in the underground <br /> tank excavation needs to be addressed by Mobil. Since the contents <br /> of the vapor drop-out tank should be of a different nature (clear_ , <br /> as gasoline would be rather than dark with the odor of diesel fuel) , <br /> it appears as though widespread subsurface contamination may exist <br /> at this site. The former practice of releasing the underground tank <br /> contents to the ground surface reinforces the idea that soil and <br /> ground water contamination at this site may be widespread. <br /> Ground water contamination at this site may also be a threat to the <br /> quality of the water in the Deep Ship Channel which is about 500 <br /> feet north-northeast of the site and the San Joaquin River which is, <br /> 1500 feet southeast of the site. <br /> Mobil has hired a consultant to provide a workplan for a subsurface <br /> investigation at this site. A report on the removal of underground <br /> tanks at the site has been received by our office. <br /> RRert t. Nibi ck <br /> Engineering Geologist <br />