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2000) Xylenes also exhibited a very slight increase from 42 8 µg11 (May 17, 2000) to 44 0 µg11 (Sept 14, 2000) and TPHg increased from 180 0 µg/1 (May 17, 2000) to 400 0 µg/1 (Sept 14, i 2000) The same increasing trend was observed for TPHg and benzene concentrations in MW3- 2 In MW3-3, TPHg increased, but all of the BTEX compounds decreased These changes in ' concentrations may be attributed to the change in groundwater height and direction For MW3-2, benzene concentrations in groundwater have risen slightly from 64 0 µg/I (May 17, 2000) to 150 0 µg/1 Toluene concentrations in groundwater have risen slightly from 174 0 µg/1 on May 17, 2000 to 660 0 pg/l (Sept 14, 2000) EthyIbenzene concentrations in groundwater increased from 19 0 ' µg/1 (May 17, 2000) to 370 0 µg/1 (Sept 14, 2000) Xylenes also exhibited an increase from 1810 µg/1 (May 17, 2000) to 530 0 µg/l (Sept 14, 2000) and TPHg increased from 790 0 µg/1 (May 17, 2000) to 6,600 0 µg/l (Sept 14, 2000) For MW3-3, benzene concentrations in ' groundwater have decreased from 93 0 µg/1 (May 17, 2000)to 37 0 µg/l Toluene concentrations in groundwater have significantly decreased from 560 0 µg/1 on May 17, 2000 to 190 0 µg/1 ' (Sept 14, 2000) Ethylbenzene concentrations in groundwater decreased from 180 0 µg/I (May 17, 2000) to 79 0 µg/1 (Sept 14, 2000) Xylenes also exhibited a decrease from 737 0 µg/l (May 17, 2000) to 330 0 µg/1 (Sept 14, 2000) although TPHg increased from 1,600 0 µg/1 (May 17, ' 2000)to 6,800 0 µg/I (Sept 14, 2000) The concentrations of ethylbenzene, and xylene in all 3 wells are below the Maximum Contamination ' Levels (MCLS) for California drinking water Per SJCEHD's concurrence, MTBE compounds were not analyzed this quarter from the wells MTBE has not been detected in any soil or groundwater samples collected at this site CONCLUSIONS/RECOMMENDATIONS ' Based on a review of the analytical results of the groundwater samples of MW3-1 through MW3-3 for BTEX and TPHg,the following conclusions are presented Free phase petroleum product has not been detected in any of the wells on the site The benzene, toluene, ethylbenzene, and xylene concentrations for MW3-3 samples of the Sept ' 14, 2000 monitoring event, decreased in comparison to the concentrations found during the May 17, 2000 monitoring event This suggests that natural attenuation, which may include intrinsic bioremediation,is continuing in the subsurface ' . TPH-g and BTEX concentrations in all wells have slightly increased, but overall still follow a declining trend except MW3-2 The concentrations of benzene in all 3 wells are above the MCL (1 0 µg11) for California idrinking water There are, however, no dnnking/potable water wells in the vicinity of this site ' • The concentrations of toluene in MW3-2 and MW3-3 are above the MCL (150 µg/1) for California drinking water, however the concentration in MW3-1 is significantly below the MCL ' . The concentrations of ethylbenzene and xylene in all 3 wells are below the MCLS for California drinking water, 700µg/l and 1750µg/1, respectively uA sft3 vas 4m 6 i