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<br /> Site History
<br /> 14000 Highway 88,Lockeford,CA
<br /> Time Oil Property No 04-049
<br /> (MW-2, MW-3, and MW-4), and increased in MW-1, however, not enough data existed to evaluate the
<br /> significance of these variations Groundwater levels decreased somewhat across the site (most likely a
<br /> result of seasonal variation) since the previous sampling event, although flow direction remained
<br /> consistent
<br /> SECOR's "Quarterly Monitoring Report, April - June 1995" dated July 13, 1995 was forwarded to the
<br /> approponate regulatory agencies on July 31, 1995
<br /> Status Report- Third Quarter 1995
<br /> On October 4, 1995, samples were collected from each of the groundwater monitoring wells (MW-1
<br /> through MW-4) at the subject site Prior to purging, the depth to water in each well was measured to
<br /> evaluate elevation, flow direction, and gradient
<br /> Analyses identified gasoline and its constituents in groundwater samples collected from each of the
<br /> monitoring wells MW-1, located nearest to the existing pump islands was found to contain 8,200 ppb
<br /> gasoline, 500 ppb benzene, 2,400 ppb toluene, 300 ppb ethylbenzene, and 1,400 ppb xylenes MW-2,
<br /> located on the northeast comer of the property and upgradient of the former tank bed, contained 320 ppb
<br /> gasoline, 9 ppb benzene, 35 ppb toluene, 5 ppb ethylbenzene, and 92 ppb xylenes The sample
<br /> collected from MW-3, located to the southeast of the former tank bed (sidegradient), contained 8,000
<br /> ppb gasoline, 560 ppb benzene, 1,400 ppb toluene, 360 ppb ethylbenzene, and 1,900 ppb xylenes The
<br /> sample collected from MW-4, located to the southwest of the former tank bed (sidegradient), contained
<br /> 180 ppb gasoline, 47 ppb benzene, 8 5 ppb toluene, 6 ppb ethylbenzene, and 15 ppb xylenes
<br />. To date, the extent of groundwater impacts have not been defined in any direction Since the previous
<br /> sampling event, gasoline concentrations in MW-1, MW-2, and MW-4 have remained relatively
<br /> unchanged, although BTEX concentrations have increased somewhat in each of the wells Additionally,
<br /> concentrations of gasoline and BTEX have increased in MW-3 by two orders of magnitude The
<br /> observed increases of hydrocarbon constituents in each well may be a result of seasonal variation in
<br /> groundwater levels, however, not enough data has been collected to evaluate the significance of these
<br /> variations Future data will be used to evaluate if significant trends in hydrocarbon concentrations in
<br /> groundwater exist
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