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Roberts Petroleum Service Facility Project No. 1628G FIELD OPERATIONS September 7, 1989 Page 3 EES measured the depth to groundwater and checked for the presence of floating product at each well using an optical interface probe. No floating product was detected in any of the wells. Groundwater samples were then collected from each well following the procedures outlined in the EES groundwater sampling protocol (Appendix A). HYDROGEOLOGY Figure 2, the Groundwater Surface Contour Map, shows a shallow gradient in the area of investigation for July 18, 1989. The contours indicate that the gradient is nearly flat with a predominant flow direction to the south-southeast. The average calculated gradient is approximately 0.007. LABORATORY RESULTS The groundwater samples were analyzed at Chemwest Analytical Laboratories, Inc. located in Sacramento, California. The results of these analyses are summarized along with past results in Table 1. No TPHG, BTEX, TPHD, or TEL contamination was detected in any of the samples by the analyses. DISCUSSION Groundwater at the site was measured in July at depths ranging from 47.25 to 48.00 feet below the existing ground surface. These depths correspond to elevations of approximately 7.17 to 7.74 feet above mean sea level based on available survey data. The groundwater surface has dropped approximately 1.40 to 2.36 feet since the previous sampling. Groundwater contours show a nearly flat gradient with an apparent southerly flow. This predominant flow direction is relatively unchanged from those calculated previously. For the second consecutive quarter none of the petroleum hydrocarbon constituents tested for were detected in the groundwater at the site by the analytical laboratory. The next quarterly sampling will be conducted in October 1989.