SITE INFORMATION AND CORRESPONDENCE_FILE 1

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cost approximately $50,000 to perform the additional tasks requested by PHS/EHD in their December 10, 1997 letter. 4. Based on my review of the documents referenced in Paragraph 2 above, and based on my experience in providing corrective action services at current and former gasoline service stations operations, I have formed an opinion as to whether or not the remaining hydrocarbon materials on this site pose an immediate risk to human health or the environment, or are likely to do so if no active remediation is undertaken over the course of the next year. It is my opinion that the remaining hydrocarbon materials present in the soil and groundwater at the Site do not pose an immediate risk to human health or the environment for the following reasons: (a)The lateral extent of the hydrocarbon plume has been delineated, except in the area of downgradient well U-9, where low concentrations of petroleum hydrocarbons were detected during the well's initial sampling event. The second sampling event for this well noted an attenuation in hydrocarbon concentrations. To complete the plume delineation,Unocal proposes to install an additional groundwater monitoring well downgradient of well U-9. (b) The hydrocarbon plume appears to be relatively stable as evidenced by groundwater analytical data, collected during fourteen consecutive monitoring events, that show hydrocarbon concentrations in groundwater have decreased over time in most wells. (c) The nearest documented downgradient water-supply well, or groundwater resource, is located approximately 1,575 feet from the site. Given that the lateral extent of the plume is estimated to be less than approximately 200 feet in length in its downgradient direction and that the plume appears stable, it is likely that the plume poses a low risk to known groundwater resources. (d) There are no drinking water supply wells on the site, nor are there any known vapor migration pathways. Therefore, it is likely that the hydrocarbon impact to soil and groundwater poses no immediate significant human health risk. 5. Based on my review of the correspondence from PHS/EHD referenced in Paragraph 2 above, it appears that there is a significant difference of opinion between, on the one hand, PHS/EHD, and, on the other hand PEG, GeoStrategies, and Unocal regarding the extent of additional characterization that is appropriate at the Site, the range of corrective action alternatives that should be considered at the Site, and the level of risk indicated by the existing data on environmental conditions at the Site. I declare under the penalty of perjury under the laws of the State of California that the foregoing is true and correct. DATED this 8th day of January, 1998,at San Jose,California. C " Jos h MuYiio