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I
<br /> to the southeast Water depth was measured on March 16, 1992 for MW-1 through
<br /> MW-3 at 32 5, 32 7 and 32 4 feet below ground surface, respectively
<br /> Artesian Environmental Consultants (Artesian)drilled three soil borings, B-1 through
<br /> B-3, on the property on May 1, 1992 The soil borings B-1 through B-3 were drilled
<br /> to depths of 45, 45 and 43 feet,respectively, below ground surface All three borings
<br /> were drilled into native material All three borings, B-1 through B-3 were
<br /> subsequently converted into monitor wells MW-4 through MW-6, respectively
<br /> Shallow groundwater was encountered in all the wells at approximately 32 feet below
<br /> ground surface
<br /> The soils were logged by a project geologist under the supervision of a California-
<br /> registered geologist. Soil samples were collected at least every 5 feet for lithologic,
<br /> and hydrologic charactenzation, as well as possible chem;cal analyses The soils
<br /> were screened with a PID Using a PID, orgaruc vapor was not detected in the soil
<br /> Iborings
<br /> oils Analysis
<br />' Soil samples were below detection hrruts (ND)for total petroleum hydrocarbons as
<br /> gasoline (TPH-g) with the exception of B-1 Borehole B-1 contained 17 ppm and 5 1
<br /> ppm TPH-g at depths of 25 Nand 30 5', respectively Benzene was detected at
<br /> levels of 47, 82, 150, 190, and 67 ppm at depths of 15.5, 20 5, 25 5, 30 5, and 35.5
<br /> feet, respectively Toluene was present at 25 5', 30 5' and 35 5' at levels of 15 ppm,
<br /> 90 ppm, 36 ppm, respectively, ethyl benzene was present at the same depths at levels
<br /> of 6 9, 22, and 13 ppm, respectively Samples collected at 15 5', 20 5', 25 5', 30 5'
<br /> and 35 5' contained xylenes at levels of 14, 6 8, 430, 780, and 36 ppm, respectively.
<br /> Groundwater Analysis
<br />' After boreholes B-1 through B-3 were converted to monitor wells MW-4 through
<br /> MW-6, Artesian sampled the wells on May 15, 1992 Samples from MW-4 and MW-
<br />' 6 showed high levels of TPH-gasoline ranging from 11,000 parts per billion (ppb) to
<br /> 6,500 ppb BTEX compounds were also present at high concentrations in both MW-
<br /> 4 and MW-6 Groundwater samples from MW-5 were non-detect for all the target
<br /> chemicals As of February 22, 1993, free product has been detected in monitor wells
<br />' MW-1, MW-2, MW-3 and MW-6 It is presently found in MW-1, MW-2 and MW-
<br /> 6
<br />' Groundwater Gradient
<br /> The monitor wells were surveyed by Duane C Kimball, of Modesto, California, a
<br /> state-licensed surveyor The wells were surveyed to within 01 foot vertically and
<br /> horizontally
<br /> Groundwater flow direction appears to vary considerably on this site Review of the
<br /> August, 1991, Kleinfelder Groundwater Assessment Report indicates that the initial
<br /> groundwater gradient "slopes generally to the east but fluctuates from east-northeast to
<br /> east-southeast " February 1991 data show groundwater to flow to the east April,
<br /> 1991 data show groundwater to flow to the southeast.
<br /> For the May 15, 1992 event the groundwater flow direction was to the north
<br /> northwest at a gradient of 0 0088 feet per foot. The August 21, 1992 sampling event
<br /> showed a similar gradient with groundwater flow to the south-southeast. For the
<br />
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