Laserfiche WebLink
i <br /> Page 4 � <br /> No contamination was detected above reportable lirmts en TT-1, 2 and 3 for the second <br /> consecutive time DM-1 detected contamination above reportable limits for the second <br /> consecutive time TPH-g was detected at 344 ug/l (ppb) which is 4 ppb higher then previously <br /> reported Xylene was reported at 14 ppb which is 13 ppb lower then was-previously reported <br /> TPH-d was detected at 7,350 ppb which represents a significant drop from the previous reported <br /> level of 130,000 ppb <br /> 5,0 CONCLUSIONS AND RECOMMENDATIONS <br /> 51 Groundwater Contamination <br /> There has been a major drop in the diesel concentration in DM-1 since February In contrast, the <br /> gasoline concentration has not changed This could suggest that the diesel is highly concentrated <br /> in a small area, whereas the gasoline is more uniformly dispersed, but it is unlikely that the <br /> diesel decline is due to biodegradation or plume migration Another possibility is that the water <br /> column is somewhat stratified, with heavier hydrocarbons (diesel) underlying lighter <br /> hydrocarbons(gasoline), and that the sample was collected closer to the water surface than the <br /> sample in February <br /> Finally, it is possible that contamination detected in DM l is related to leaking underground fuel <br /> tanks, but rather to other sources Because the casing is a confined space, it is possible that <br /> contaminated water within DM-1 could be removed by performing an extensive purge The <br /> most effective flushing of the casing would take place if the pump intake was placed at an <br /> elevation near the water surface This should be done before the well is destroyed <br /> I <br /> Upgradient recommends continued quarterly monitoring until is has been determined that the <br /> contaminant plume is stable The next monitoring should be scheduled for mid July 1996 <br /> yl <br /> J <br /> ' 4 � <br />