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<br /> Total petroleum hydrocarbons as diesel (TPHd) were detected in borings B-1 through B-7 at
<br /> concentrations up to 700 parts per million (ppm). Total petroleum hydrocarbons as gasoline
<br /> (TPHg) were detected in borings B-1 through B-3 at maximum concentrations of 1,900 ppm.
<br /> Benzene was detected in borings B-2, B-3, and B-6 at concentrations up to 3.9 ppm. Shallow soil
<br /> samples from boring B-3 were also analyzed for total recoverable petroleum hydrocarbons; none
<br /> were detected. Groundwater samples collected from the borings contained 1,600 to 12,000 parts
<br /> per billion (ppb)TPHd, 23,000 to 150,000 ppb TPHg, and 970 ppb to 13,000 ppb benzene. This
<br /> investigation is described in Geosystem's August 1995 Phase I and Phase II Site Assessment.
<br /> 1997 Soil Borings: During April 1997 Enviros Inc. (Enviros) of Sonoma, California drilled
<br /> five Geoprobe soil borings (SB-1 through SB-5). Soil and groundwater samples were collected
<br /> from all of the borings. Soil samples from all the borings contained TPHd at concentrations
<br /> ranging from 1.3 to 260 ppm. Soil from borings SB-1, SB-2, SB-4, and SB-5 contained up to
<br /> 890 ppm TPHg. Benzene was detected in soil from boring SB-2 at maximum concentrations of
<br /> 0.11 ppm. Methyl tertiary butyl ether (MTBE) was reported by EPA Method 8020 in samples
<br /> from borings SB-1, SB-2, and SB-5 at concentrations up to 4.1 ppm. No confirmation analysis
<br /> was performed at that time. Soil samples from boring SB-2 were also analyzed for cadmium,
<br /> chromium, lead, nickel, zinc, oil and grease, halogenated volatile organic compounds (HVOCs),
<br /> and semi-volatile organic compounds (SVOCs). This boring contained 37 to 45 ppm chromium,
<br /> 7.0 ppm lead, 36 to 39 ppm nickel, 43 to 52 ppm zinc, 184 ppm oil and grease, and 770 to
<br /> 930 ppm phenol. No other waste oil constituents were detected in soil.
<br /> Groundwater samples were also collected from all the borings. TPHd was detected in
<br /> groundwater from all the borings at concentrations ranging from 430 to 25,000 ppb. TPHg and
<br /> benzene were detected in borings SB-1, SB-2, SB-4, and SB-5 at concentrations ranging from
<br /> 15,000 to 38,000 ppb and 220 to 1,900 ppb, respectively. MTBE was also reported in these
<br /> borings by EPA Method 8020 at concentrations ranging from 110 to 370 ppb. The sample with
<br /> the highest MTBE reported was also analyzed by EPA Method 8260 and none was detected
<br /> (<50 ppb). Groundwater samples from boring SB-2 were also analyzed for cadmium, chromium,
<br /> lead, nickel, zinc, oil and grease, HVOCs, and SVOCs. This boring contained 1.1 ppb
<br /> chromium, 1.2 ppb nickel, 1.6 ppb zinc, 51 ppb 1,2-dichloroethane (1,2-DCA), 390 ppb
<br /> 2-methylnaphthaelene, and 350 ppb naphthalene. The chromium, nickel, and zinc levels are
<br /> below California maximum contaminant levels (MCLs), and there are no California MCLs for
<br /> 2-methylnaphthaelene or naphthalene. This investigation is summarized in Enviros'
<br /> July 10,1997 Site Investigation Report.
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