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KLEINFELDER
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<br /> 6 CONCLUSIONS AND RECOMMENDATIONS
<br /> On March 21, 22, and 23, 2005, 9 monitoring wells and 3 piezometers were purged and sampled.
<br /> Water samples obtained from each location were submitted for chemical analysis.
<br /> Based on the data obtained during our assessment, the following conclusions and
<br /> recommendations have been formulated:
<br /> i 1. Groundwater flow direction at the site shifted towards the east/southeast with a
<br /> relatively flat gradient of 0.0003 ft./ft. in the western portion of the site to 0.0005 ft/ft
<br /> in the eastern portion of the site. This marks a continued groundwater flow direction
<br /> shift from the previously calculated flow directions towards the south and southeast.
<br /> 2. The seven downgradient well samples (MW-DIS-Ils, MW-DIS-11d, MW-DIS42,
<br /> MW-DIS-13, MW-DIS-14s, MW-DIS-14d and MW-DIS-15) all showed non-
<br /> detectable concentrations of TPH-g, BTEX, TBA, and EDB. Concentrations of 1,2-
<br /> DCA were detected in MW-DIS-1 ls, MW-12, MW-DIS-14s, and MW-DIS-15. The
<br /> 1,2-DCA concentration in MW-DIS-11s decreased approximately 97% from the
<br /> previous quarterly results (down to 7.6 ug/1). 1,2 DCA was detected in MW-DIS-12
<br /> at a concentration of 1.6 ug/l up from a previous quarter of non-detect and 0.64 ug/l.
<br /> MW-DIS-14s continued to show a decreasing trend during the 2004 monitoring
<br /> period (down to 1.6 ug/l from 3.2 ug/l, the lowest since monitoring began). It should
<br /> �. be noted that the concentration of 1,2-DCA reported for MW-DIS-15 was the lowest
<br /> since monitoring began (1.7 ug/1) at this location. The additional oxygenates MTBE,
<br /> DIPE, ETBE, and TAME (MW-DIS-15 was the only well analyzed for these
<br /> i constituents)were non-detectable at or above the laboratory reporting limits.
<br /> Decreases in the concentrations of benzene, toluene, and xylenes were noted in MW-
<br /> DIS-1, as well as benzene concentrations in MW-DIS-2. Increases were noted in
<br /> TPH-g, toluene, xylenes, (MW-DIS-2 only), 1,2 DCA, (MW-DIS-1) and
<br /> ethylbenzene. The 1,2 DCA concentration was approximately 80% increase and has
<br /> E appeared to fluctuate historically. EDB was also detected at 10 ug/l for the first time
<br /> since October of 2001 in MW-DIS-1.
<br /> The three piezometers sampled this quarter (NP-70', NP-80', NP-90') all showed
<br /> decreased or steady concentrations of TPH-g, ethyl-benzene, and xylene compared to
<br /> last quarter, and further showed a fluctuating pattern of detected concentrations over
<br /> time. The benzene and 1,2 DCA concentrations increased slightly in NP-90' and
<br /> NP-70'; whereas in NP-80' benzene decreased and 1,2 DCA decreased. The samples
<br /> showed non-detectable results for the fuel oxygenates TBA, MTBE, DIPS, ETBE,
<br /> and TAME. The EDB concentrations in the piezometers decreased this quarter,
<br /> with the exception of NP-70' where the EDB concentration increased.
<br /> 12280,M0N/ST05R613/JZ:1V Page 11 of 13
<br /> 10 2005,Kieinfelder,Inc. May 20,2005
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