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CV1V
<br /> A S S O C I A T E S I N C
<br /> The groundwater matrix samples collected from each well were submitted to State-certified
<br /> Argon Laboratories (ELAP Cert. No. 23 59)for chemical analysis of TPHg utilizing EPA method
<br /> 8015 modified, and BTEX and oxygenate fuel additives including MTBE utilizing EPA method
<br /> 8260. Groundwater well purge and sample logs are contained in Attachment 1.
<br /> ANALYTICAL RESULTS
<br /> The groundwater analytical results measured at monitoring wells MW1, MW2, and MW3
<br /> showed detectable concentrations of TPHg, BTEX, MTBE, TBA, and 1,2-DCA.
<br /> The measured concentration of TPHg at MW 1 was 1,700 gg/L. Benzene was detected at 10
<br /> Vg/L, toluene was detected at 1.5 pg/L, ethylbenzene was detected at 70 gg/L, and xylenes were
<br /> detected at 25 gg/L. MTBE was detected at 23 gg/L, TBA at 28 µg/L, and 1,2-DCA at 10 pg/L.
<br /> The measured concentration of TPHg at MW2 was 3,400 pg/L. Benzene was detected at 17
<br /> gg/L, toluene was detected at 7.2 gg/L, ethylbenzene was detected at 56 gg/L, and xylenes were
<br /> detected at 130 gg/L. MTBE was detected at 64 gg/L, TBA at 75 gg/L, and 1,2-DCA at 49
<br /> gg/L-
<br /> The measured concentration of TPHg at MW 1 was 1,400 gg/L. Benzene was detected at 0.6
<br /> Vg/L, toluene was detected at 3.8 pg/L, ethylbenzene was detected at 5.9 gg/L, and xylenes were
<br /> detected at 26 pg/L. MTBE was detected at 170 gg/L, TBA at 68 gg/L, and 1,2-DCA at 84
<br /> pg/L.
<br /> The Maximum Contaminant Level (MCL) for benzene, 1 gg/L, was exceeded at monitoring
<br /> wells MW1 and MW2 which had detected concentrations of 10 gg/L and 17 gg/L. The MCL for
<br /> MTBE, 13 gg/L, was exceeded at MW1, MW2, and MW3, which had detected concentrations of
<br /> 23 gg/L, 64 gg/L, and 170 gg/L, respectively.
<br /> GROUNDWATER FLOW DIRECTION
<br /> Water level measurements were collected from monitoring wells MW 1, MW2, and MW3 on
<br /> April 22, 2002. Water level elevations ranged from —21.44 to —21.47, representing an average
<br /> increase in water table elevation of approximately 2.80 feet since November 2001. The water
<br /> level data were used to develop the groundwater elevation contour map (Figure 3). Assuming
<br /> that horizontal isotropic conditions prevail, groundwater in the uppermost aquifer beneath the
<br /> site flowed towards the northeast. The average hydraulic gradient on April 22, 2002 was
<br /> calculated to be 0.0005 or approximately 3 ft/mile. A summary of groundwater monitoring data
<br /> is presented in Table 1.
<br /> ADDITIONAL SITE ACTIVITES
<br /> On April 9, 2002, sixteen drums of soil generated from the monitoring well installation event of
<br /> • November 2001 were transported off site for disposal. The drums were transported under non-
<br /> hazardous waste manifest to Forward Landfill located in Stockton, California. A copy of the
<br /> non-hazardous waste manifest is included as Attachment 3.
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