SITE INFORMATION AND CORRESPONDENCE

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William S. Peters Peters Enterprises Page 3 of 4 contaminant migration from the Chevron site to the Kwikee site. EHD views this as a working hypothesis that should be demonstrated and tested through development of a detailed site conceptual model (SCM), which will be discussed further below. • To interpret the increased contaminant concentrations detected in sample KF-3 as contradicting EHD's January 2002 suggestion that higher contaminant concentrations may be in soil east of the well stretches the importance of the rather modest concentration increase. Hydrocarbon concentration data can be noisy and influenced by such factors as proximity to source, temperature in air and ground water, purging and sampling techniques, flow direction, and ground water elevation to name a few. The data must be carefully examined and the controlling factors identified to evaluate cause and effect. The results from one sampling event, in an area of known contamination, are hardly definitive. As an example, the last time the ground water elevation was near its 24 May 2002 level was on 14 February 2001, during an extended period of the DPE unit operation on the Chevron site. During this event, when ground water flow was presumably toward the west, TPH-g concentrations increased from 679 ppb to 2,520 ppb in KF-3. The data from this one event would clearly contradict the model proposed by UEC if only data from single monitoring events are considered. An example of using long- term trends would be EHD's interpretation of the sudden decrease of contaminant concentrations between November 1997 and May 1998 as a result of a ground water elevation increase of approximately 8 feet, with the water table going over the well screens. Drowning of the wells may have been the most important factor in the apparent cleaning up of the dissolved hydrocarbons. Data from a number of sampling events must be obtained to show data trends and associate the trend with the controlling factors. • The reiterated statement from First Quarter 2002 Report shows that UEC recognizes that the ground water seepage velocity is slow, and that effects from the DPE remediation effort will take considerable time to document. The seepage velocity can be expected to decrease exponentially with distance from the pumping influence. Interestingly, the statement pre- interprets occasional contaminant increases during operation of the DPE unit as to not be inconsistent with the contention that the contaminants are from the Chevron site. Thus, whether the DPE unit is in operation or not, an increase of concentrations can be favorably interpreted! Again, the results from a single monitoring event cannot demonstrate a trend. • At this time, EHD cannot concur with UEC's contention that the site be closed with no further action or that responsibility for the contaminants be transferred to the responsible party for the former Chevron site. EHD believes the Kwikee site requires further characterization. EHD has been informed that the Central Valley Regional Water Quality Control Board