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Ron E. Senner August 11, 1994 Page 2 Report") provided to Wells Fargo Bank by L.M. Swift & Associates. Your first contention is that,the high levels of benzene on the northern boundary of the Site are not consistent with petroleum contamination during the period of Unocal's operations on the Site. The text of the Swift Report does indeed state that benzene was found at the level of 5,900 parts per million. However, Appendix B to the Swift Report clearly indicates that the actual measurement was 5,900 parts per billion, or 5.9 parts per million. Mr. Swift has confirmed that the text unfortunately misstated the actual measurement results. I am informed by Mr. Swift and by our internal, engineers that the correct level of benzene, as shown in Exhibit B to the Swift Report, is not uncommon for contamination during the period of Unocal's operations. Mr. Howard further states that benzene was not detected in the ground water sample taken from boring B-3. However, it did contain relatively high concentrations of other volatiles associated with gasoline. Benzene and other volatiles associated with gasoline were also detected in boring B-1. Both of these borings are located on the north edge of the Site. Again, our consultants confirm that the levels and locations of petroleum and/or volatile constituents found on the north side of the Site, together with Unocal's acknowledgement that their tanks were located in this same location, indicates that this location, and Unocal's activities thereon, should be the primary suspect as the source of the subject contamination. I I Mr. Howard also draws attention to the fact that in 1951 a Chevron Gasoline Station was located across 11th Street to the north of the Site, and that this property may be a possible source of contamination. This property was dismissed by the Swift report as a source of contamination because it lies down-gradient from the subject Site at a distance of 400 feet. In addition, remediation-on the Chevron site has been undertaken and the water quality control board gave the site closure status in August 1993. Therefore, contamination of our Site from the Chevron property is not very plausible. Mr. Howard points out that twelve additional sites with 1/2 mile of the Site have been listed by the Regional Water Quality Control Board on its list of Leaking Underground Storage Tanks. However, the Swift Report also points out that all are either down-gradient or cross- gradient from the subject Site. In addition, all but the M & M Automotive site lie at distances of 1000 to 2500 fest from the Site. The Swift Report concludes that, except as to the M & M Automotive site, the distance and gradient conditions make it unlikely that these properties affected the Site's soil and ground water. Mr. Howard provides no adequate basis for doubting this conclusion, but rather merely states that the other sites exist. 7 Finally, as to the M & M Automotive site, our internal environmental engineer has obtained information from Environmental Risk Information & Imaging Services, a data base reporting service, that the M & M Automotive site may actually lie as far as 350 feet east (cross- gradient) of the Site and that only soil contamination was indicated. The lack of ground ..nVxcn=.0M i