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<br /> Artesian Environmental Consultants
<br />' 1991, 15 feet of free product was measured in MW-1 At that time no free product
<br /> or sheen was observed in any of the other wells
<br />' Artesian Environmental Consultants (Artesian) measured hydrocarbon thickness in
<br /> MW-1 on March 16, 1992 to be 182 feet Groundwater flaw direction on March 16,
<br /> 1992 was to the southeast Water depth was measured on March 16, 1992 for MW-1
<br />' through MW-3 at 32 5, 32 7 and 32 4 feet below ground surface, respectively
<br /> Artesian drilled three soil borings, B-1 through B-3, on the property on May 1, 1992
<br />' The soil borings B-1 through B-3 were drilled to depths of 45,45 and 43 feet,
<br /> respectively, below ground surface All three borings were drilled into native
<br /> material All three borings, B-1 through B-3 were subsequently converted into
<br />' monitor wells MW-4 through MW-6, respectively Shallow groundwater was
<br /> encountered in all the wells at approximately 32 feet below 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 characterization, as well as possible chemical analyses The soils
<br /> were screened with a PID No organic vapors were detected in the soil borings while
<br />' screening with a PID
<br /> Soils Analysis
<br /> Soil sample analyses were below detection limits (ND) for TPH-g with the exception
<br /> of B-1 Borehole B-1 contained 17 ppm and 5 1 ppm TPH-g at depths of 25 5' and
<br /> 30 5', respectively Benzene was detected at levels of 47, 82, 150, 190, and 67 ppm
<br /> at depths of 15 5, 20 5, 25 5, 30 5, and 35 5 feet, respectively Toluene was present
<br /> at 25 5', 30 5' and 35 5' at levels of 15 ppm, 90 ppm, 36 ppm, respectively, ethyl
<br /> benzene was present at the same depths at levels of 6 9, 22, and 13 ppm,
<br /> I respectively Samples collected at 15 5', 20 5', 25 5', 30 5' and 35 5' contained
<br /> 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 groundwater monitoring wells
<br /> MW4 through MW-6, Artesian developed and sampled the wells on May 15, 1992
<br /> Samples from MW-4 and MW-6 showed high levels of TPH-gasoline ranging from
<br /> 11,000 parts per billion (ppb) to 6,500 ppb BTEX compounds were also present at
<br /> high concentrations in both MW-4 and MW-6 Groundwater samples from MW-5
<br /> were non-detect for all the target chemicals As of February 22, 1993, free product
<br /> has been detected in monitor wells MW-1, MW-2, MW-3 and MW-6 at thicknesses
<br /> ranging from 1 82' in MW-3 (April 15, 1992) to 0 02' m monitor well MW-6
<br /> (February 22, 1993) It is presently found in MW-1 and MW-2 A passive skimmer
<br /> installed in MW-1 has removed almost 7 Iiters of free product from the groundwater
<br /> interface since its installation in March of 1992
<br /> Groundwater Gradient
<br /> The monitor wells were surveyed by Duane C Kimball, of Modesto, California, a
<br /> California state-licensed surveyor The wells were surveyed to within 01 foot
<br /> Ivertically and horizontally
<br /> 3175 Kerner Blvd, Suite E• San Rafael,CA 94901 • (415) 257-4801 -FAX (415) 257-4805
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