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1 <br />' Laboratory results for groundwater samples collected during the 12-hour groundwater extraction <br /> treatability test indicated that detectable concentrations of petroleum hydrocarbon constituents were <br /> present in groundwater samples collected priorto and after extraction testing of well MW-11 Using <br /> EPA Method 8015 (modified for gasoline) and 8020, TPH and BTEX were detected in the <br /> groundwater sample collected 5 minutes prior to the extraction test at concentrations of 160,000 µg/1 <br />' for TPHg, 33,000 pg/1 for benzene, 45,000 gg/l for toluene, 3,100 µg/1 for ethylbenzene, 22,000 µg/1 <br /> for total xylenes, and 3,500 pg/l for MTBE The presence of MTBE was confirmed using EPA <br /> Method 8260 at a concentration of 3,000 µg/1 <br />' Petroleum hydrocarbons were detected in the groundwater sample collected after 12 hours of <br /> extraction at concentrations of 97,000 gg/l for TPHg, 25,000 gg/l for benzene, 31,000 µg/1 for <br />' toluene, 2,800 µg/1 for ethylbenzene, 15,000 µg/1 for xylenes and 3,000 µg/1 for MTBE The <br /> presence of MTBE was later confirmed by using EPA Method 8260 at a concentration of 2,300 µg/1 <br /> A summary of the analytical results of Extraction Test 1 are presented in Table 4 <br />' In the surrounding groundwater monitoring wells, TPH was detected at concentrations ranging from <br /> ND to 760 gg/l for TPH,ND to 2 1 µg/1 for benzene, ND to 0 98 pg/1 for toluene, ND to 0 48 µg/1 <br />' for ethylbenzene,ND to 14 µg/1 for xylenes, and ND to 540 µg/1 for MTBE The presence of MTBE <br /> was confirmed by using EPA Method 8260 at a concentrations ranging from ND to 490 µg/1 <br />' The newly installed groundwater monitoring well MW-12 contained detectable concentrations of <br /> TPH at 21,000 µg/1, benzene at 3,200 µg/1, toluene at 4,100 µg/1, ethylbenzene at 32 µg/1, total <br /> xylenes at 6,600 µg/1, and MTBE at 150 µg/1 MTBE was later verified by EPA Method 8260 at a <br /> concentration of 120 µg/1 A summary of the groundwater analytical results is included as Table 3 <br /> 4.4 Petroleum Hydrocarbon Recovery <br /> Approximately 4 38 pounds of gasoline were recovered from groundwater during the extraction test <br />' (2,800 gallons of water at average concentration of 128,500 µg/l for TPH) The results of laboratory <br /> analyses of groundwater samples collected from MW-11 are included in Table 4 <br />' 5.0 GROUNDWATER EXTRACTION RESULTS <br />' Park performed a 12-hour groundwater extraction treatability test of the first water-bearing zone on <br /> March 30, 1999 The test was comprised of the following <br />' 12-hour groundwater extraction test at approximately 4 gpm (Well <br /> MW-11) Increased flow rates resulted in groundwater extraction in <br /> excess of the recharge capacity of the aquifer, <br />' Water levels were measured at frequent intervals in the extraction well <br /> and observation wells Serio-log plots of the measured drawdown vs <br /> 1 <br /> A.11528J1 ASA 1 <br />