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• <br /> Groundwater Gradient <br /> Groundwater elevations were plotted to a known datum to prepare a groundwater contour map <br /> The groundwater flow direction was toward the north-northeast at sampling time, and a flow <br /> gradient of 0 032 was calculated Water levels have dropped roughly 0 2 feet, and this decline <br /> is normal aquifer discharge Historic groundwater flow trends typically vary from north- <br /> northeasterly to north-northwesterly <br /> Chemical Analysts and Results <br /> The samples were transported to Chromalab, Inc in Pleasanton, CA The groundwater samples <br /> were analyzed using EPA Methods 50301 8015 and 602 for Total Petroleum Hydrocarbons as <br /> Gasoline (TPHG), Benzene, Toluene, Ethylbenzene and Xylene (BTEX) and fuel oxygenates <br /> including Methyl-tert-butyl-ether (MTBE) by EPA Method 8260 The analytical reports are <br /> attached, and the results are listed below in Table 2 (see Table 3 for historic data) <br /> Table 2 Groundwater Chemical Data <br /> Well No Date TPHG" Benzene Toluene Ethylbenz Xylene Fuel Ox <br /> ug/I ----------------------------- <br /> MW-1 9/29/98 8,400 960 92 860 580 ND <br /> MW-2 9129/98 NO NO NO ND NO NO J <br /> MW-3 9129/98 NO NO NO N3 NO NO <br /> MW-4 9/29/98 NO ND ND ND ND NO <br /> Blank 9129198 NO NO NO ND NO NO <br /> NO - None detected NA - Not Analyzed ug/l - micrograms per liter <br /> Fuel Ox - Fuel oxygenates including MTBE by Method 8260 <br /> Discussion <br /> Groundwater flow direction appears consistent with historically observed trends The <br /> concentrations in Well MW-1 similar with slight declines to the previous quarter and are <br /> attributed to residual contaminants desorbing into the groundwater from the soil strata to the <br /> immediate vicinity of the former tank pit MTBE was not detected in any well Well MW-4 <br /> showed contaminants not detected <br /> Conclusions and Recommendations <br /> The PHS-EHD has requested that bids be solicited for the Wright recommended soil excavation in <br /> the immediate tank pit area, as well as a well search this information will be used to remove <br /> residual contaminants in order to attain site closure in the future Wright recommends that the <br /> quarterly monitoring for this site continue at quarterly intervals <br /> Page 3 <br />