SITE INFORMATION AND CORRESPONDENCE

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CONESTOGA-ROVERS &ASSOCIATES November 30, 2009 -3- Reference No. 060223 assistance from Shell Global Solutions (SGS) which CVWB staff have referenced. This investigation included evaluating soil and groundwater samples collected from borings B-61 and B-66 at depths of 30, 132, and 171.5 ft bgs (Clayton, 22 April 2004). Clayton and SGS performed a second forensics investigation which included evaluating soil samples collected from boring B-69 at depths of 20.5, 40.5, 70.5, and 130.5 ft bgs, and groundwater samples collected from depths of 90, 110, 130, and 150 ft bgs (Clayton,28 September 2005). The findings of both investigations showed that differences exist between the site samples and the crude oils carried through the pipelines. The forensic research also demonstrated that the hydrocarbons detected at 171.5 ft bgs are clearly unrelated to the pipelines and appear to be naturally occurring. The forensics findings also suggested that the hydrocarbons detected below 50 ft bgs are different in nature compared to the shallower hydrocarbons. Investigative work following the forensics research was limited to 150 ft bgs. Although Shell believes sufficient lines of evidence have been provided to substantiate the differences between shallow and deep hydrocarbons, additional forensics research will be conducted. SGS will perform the work using similar procedures to the previous two investigations. Soil and groundwater samples will be collected during the monitoring well installation field work proposed in CRA's 15 October 2009 work plan and the samples will be provided to SGS for forensics testing. A work plan addendum will be prepared outlining the testing procedures and submitted to CV WB staff for approval. PROPOSED PLAN FOR WATER SUPPLY WELL SAMPLING The sensitive receptor survey results identified three water supply wells within 2,000 feet of the site. The three wells are located approximately 1,000 ft northwest of the site near the former pipelines. Based on surface topography the groundwater flow direction is anticipated to be toward the northeast (SAIC, 26 June 2006), which positions the water supply wells crossgradient of the site. The well logs report that the wells are being used for domestic purposes and are screened greater than 90 ft bgs. The following work tasks and schedule are proposed for sampling the water supply wells. Worldwide Engineering, Environmental, Construction, and IT Services