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<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 Table 2 1n
<br /> the attached report summanzes histoncal analytical data, and the laboratory reports for the most recent
<br /> sampling event are included as Appendix B
<br /> Fourth Quarter 1995 _Groundwater Sampling Results- December 1995
<br /> On December 19, 1995, samples were collected from each of the groundwater monrtonng wells (MW-1
<br /> through MW-4) at the subject site by a representative of SECOR Pnor to purging, the depth to water in
<br /> each well was measured to evaluate elevation, flow direction, and gradient
<br /> MW-1 was found to contain 3,400 ppb gasoline, 200 ppb benzene, 850 ppb toluene, 120 ppb
<br /> ethylbenzene, and 560 ppb xylenes The sample collected from MW-3 contained 1,800 ppb gasoline,
<br /> 140 ppb benzene, 180 ppb toluene, 78 ppb ethylbenzene, and 260 ppb xylenes, and the sample
<br /> collected from MW-4 contained 410 ppb gasoline, 65 ppb benzene, 3 6 ppb toluene, 28 ppb
<br /> ethylbenzene, and 4 1 ppb xylenes The table attached to the Time Oil Co summary of site activities
<br /> reiterates all groundwater data collected to date
<br /> Upon completion, SECOR's quarterly groundwater monitoring report which presents analytical results
<br /> and contains field observations collected dunng Fourth Quarter 1995 sampling activities will be
<br /> • forwarded for your review
<br /> Conclusions
<br /> To date, the extent of groundwater impacts have not been defined in any direction Between the Third
<br /> and Fourth Quarters of 1995, gasoline and BTEX concentrations increased slightly in MW-4, however,
<br /> they decreased in MW-1 MW-2, and MW-3 The observed fluctuations in hydrocarbon concentrations
<br /> may be a result of seasonal variation in groundwater levels and/or a result of bioattenuation, however,
<br /> not enough data has been collected to evaluate their significance Future data will be used to evaluate if
<br /> significant trends in hydrocarbon concentrations in groundwater exist
<br /> Future Site Activities
<br /> SECOR has prepared a workplan for the installation of six additional monitoring wells to define the extent
<br /> of sod and groundwater impacts associated with the former underground storage tanks at the subject site
<br /> Bnefly, proposed site activities consist of the following
<br /> 1 Six bonngs will be advanced to approximately 100 feet below ground surface (or to 10 feet below
<br /> first encountered groundwater) at the locations identified on Figure 2 of the enclosed workplan
<br /> 2 Soil samples will be collected from each bonng at 5-foot intervals and submitted for gasoline and
<br /> BTEX analyses based on visual observation and field instrumentation readings A minimum of three
<br /> samples will be submitted from each boring
<br /> 3 Two-inch diameter groundwater monitonng wells will be installed in each of the bonngs Each of the
<br /> wells will be screened from 5 feet above to at least 10 feet below the first encountered groundwater
<br /> . 4 The completed wells will be developed, surveyed, and sampled
<br />
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