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. KEI-P91-0202 .R6 January 23 , 1992 Page 4 _ Figure 1) were installed at the site. The monitoring wells were drilled and completed to total depths ranging from 82 to 86 feet below grade. Ground water was encountered at depths ranging from 73 to 75 feet beneath the surface during drilling. The surface of each well cover was surveyed by Kier & Wright of Pleasanton, California, to Mean Sea Level (MSL) and to a vertical accuracy of 0. 01 feet. The wells were attempted to be developed on September 3 , 1991 . However, field data collected indicated that sand and silt materials remained in the water within the well casing. The wells were initially sampled on September 9, 1991. Water and selected soil samples were analyzed at Sequoia Analytical Laboratory in Concord, California. Soil and water samples were analyzed for TPH as gasoline and BTX&E. Analytical results of the soil samples collected from the borings for monitoring wells MW1, MW2 , and MW3 indicated non-detectable • levels of TPH as gasoline and BTX&E, except for samples MW1 (27.5) , MW1 (32 . 5) , and MW1 (42 . 5) , which showed levels of TPH as gasoline ranging from 1 . 9 ppm to 5.0 ppm, and levels of benzene ranging from 0. 45 ppm to 1. 9 ppm. In addition, sample MW1 (37 . 5) showed a benzene level of 0. 0094 ppm. Relatively minor amounts of toluene, xylenes, and ethylbenzene were also detected in these four samples. Analytical results of the ground water samples collected on September 9 , 1991, from monitoring wells MW1 and MW2 indicated levels of TPH as gasoline at 660 ppb and 240 ppb, respectively, with benzene levels at 96 ppb and 13 ppb, respectively. In MW1, TPH as gasoline was non-detectable, with benzene at 0.49 ppb. Results of the soil analyses are summarized in Table 4 , and results of the water analyses are summarized in Table 2. Based on analytical results, KEI recommended the implementation of a monthly monitoring and quarterly sampling program of the existing wells. In addition, wells MW1, MW2 , and MW3 were recommended to be redeveloped during the following quarter, due to observations made during the initial ground water sampling activities that indicated the presence of some sand and silt materials at the bottom of the well casings . (It should be noted that, because the wells were apparently not initially completely developed, the original samples collected from these wells may not be representative of the actual ground water quality at the site. )