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i <br /> i1 <br /> E <br /> i i I <br /> most likely due ,,to permeability differences within the sands & <br /> clays beneath the site, or; (2) there are multiple withdrawal <br /> points that pump intermittently. Field data shows that recharge , <br /> is quite slow; this supports the well logs which indicate very <br /> minor amounts of sand in the three wells . We are not aware of <br /> any groundwater'lremediation projects within the zone of influence <br /> that might cause such wide fluctuations in the hydraulic gradient <br /> at this location. The variations in water table depths appear to <br /> be related primarily to seasonal changes in rainfall and with- <br /> drawals & recharge from deeper aquifers . There does not appear <br /> it to be a correlation between gradient direction and levels of <br /> contamination observed in ',MW--1 , or between water depth and con- <br /> tamination. .1 <br /> !' <br /> CONCLUSIONS: <br /> 1 . 17 water level measurements over a period of almost 2 years <br /> (EXHIBIT A, ) has not defined a uniform hydraulic gradient . <br /> 2. All three wells have been in downgradient positions at <br /> various times since monitoring began. <br /> 3 . There is nolapparent correlation with either hydraulic gra- <br /> dient or variations in water table depth and levels of- ground- <br /> water <br /> fground- <br /> water contamination measured in MW-1 . <br /> 4. As shown oniTABLE L, the amounts of contamination measured in <br /> MW-1 has decreased significantly between the June, 1993 & the r <br /> January, 1994 sampling periods . <br /> 5 . Due to the fluctuating hydraulic gradient, the minor amounts <br /> of contamination detected ?in the water, and the apparent static <br /> condition of the water table, additional monitoring wells do not <br /> appear to be warranted. <br /> RECOMMENDATION:11 <br /> i <br /> Based upon an analysis of '�all of the data obtained to date, we <br /> believe that the minor amount of contamination recorded beneath <br /> this site does not now, or will in the future, present a threat <br /> to the groundwater. The processes of natural biodegradation will <br />( eliminate what little pollutants remain; it is apparent that the <br /> water beneath the site is relatively static, and has not moved <br /> offsite. Therefore, additional work on this property does not <br /> appear justified. <br /> i <br /> We do recommend that quarterly monitoring of MW-1 should continue <br /> for at least two more sampling periods - without the monthly <br /> 2 <br /> I I� <br />