ARCHIVED REPORTS_XR0003203 - Laserfiche WebLink

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� kbn A 5 S O C I A T E S I N C hydrocarbons other than low concentrations of MTBE The samples collected from MW3, MW8 ' and MW 10 contained no detectable concentrations of petroleum hydrocarbons There are petroleum hydrocarbons remaining in the soil and groundwater The direction of groundwater flow and the magnitude of hydraulic gradient are generally consistent with the previous event Groundwater elevations have decreased slightly since September 2003 The vapor extraction system is operating at approximately 170 cfin and petroleum hydrocarbon vapor concentrations in vapor wells VW 1 through V W4 decreased during the fourth quarter with respect to the third quarter 2003 analytical results The vapor extraction system is collecting an average of approximately 23 7 gallons per hour of groundwater/ condensate in the knockout tank from vapor wells V W 1, V W2, V W3, and V W4 The air sparge system appears to be operating within design parameters RECOMMENDATIONS Based on the results of the Fourth Quarter 2003 monitoring event, we recommend the following • Because of remaining elevated concentrations in well MW1, ATC is connecting MW1 to the extraction system network A stinger will be installed in well MW 1 to allow for extraction of vapor and groundwater from the well The current vapor and groundwater extraction system will accommodate the additional volume of groundwater 1 condensate and vapor extracted from well MW 1 ' • Conduct the First Quarter 2004 groundwater monitoring and sampling of wells MW1 through MW10 and CW and analyze samples for TPHg and BTEX by EPA methods 8015B and 8021B, respectively, and MTBE, ETBE, TBA, TAME, and DIPE by EPA method 8260B • Continue monthly monitoring of the vapor extraction system, groundwater treatment and ' discharge system, and air sparge system i s\env tro1625961quari1yl4gr-2003 doc 8