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kn KLEINFELDER f 4 RESULTS 41 GROUND WATER GRADIENT On June 2, 1989, the local ground water gradient in the vicinity of the Unocal facility was to the east-southeast. The overall gradient direction did not appear to change throughout the day in response to the tidal fluctuations in the San Joaquin River. The water level in the San Joaquin River changed by approximately 3 5 feet over the period of water level monitonng The tidal fluctuations are shown in Plate 4. The contours of ground water elevation for morning, afternoon, and evening are shown in Plates 5, 6, and 7, respectively Data from piezometers with more than 0 1 foot of floating product were not included in the contouring because the floating product likely creates a measurable depression in the water table. While correction factors based on the density ratio of product and water can be applied, these factors are often inaccurate when the product thickness is small. Therefore, data from P11, P12, and P16 (which contained 033, 021, and 038 feet of product, respectively) were not contoured 4 2 GROUND WATER ANALYTICAL RESULTS No BTEX or TPH were detected in any of the wells on the Unocal facility, with the exception of MW-5. BTEX and TPH (described by the laboratory as an unknown hydrocarbon) were detected in MW-5 These results, and the results of previous sampling in July 1988, are shown in Table 3 i 4 3 FLOATING PRODUCT ANALYTICAL RESULTS The two samples of floating product collected from piezometers P12 and P16 along Stork Road were identified by the analytical laboratory as being composed largely of gasoline with some diesel Diesel comprises about 0.5 percent of the sample collected from P16 (east of Unocal) and about 5 percent of the sample collected from P12 (north-northeast of Unocal) The results are as follows: Sample Location Sample ID TPH as diesel (mg/1) TPH as gasoline (mg/1) P12 19290 53,000 1,000,000 P16 19289 7,600 1,700,000 194-89-1112 8