ARCHIVED REPORTS XR0008192 - Laserfiche WebLink

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John Margowski Page 2 day All of the vapor wells which are currently plumbed to the vapor extraction system were installed July 1992 as a result of contamination which was detected during confirmation soil sampling (see below) PHS/EHD recommends the continued operation of the vapor extraction system with consideration given to pulsing the system to allow equilibration of soil vapor concentrations Well screen sand pack soil contamination vapor sample July 1992 April 1993 VSB3 35-45' 25-45' 30-35' 1,500 ppm TPH 014 ppm TPH VSB5 27-37' 20-37' 20-30' 100 ppm TPH 107 ppm TPH VSB9 45-55' 15-55' 15-55' 11,000 ppm WH 0 90 ppm TPH VSBI1 30-40' 12-40' 15-30' 1,800 ppm TPH 3 44 ppm TPH Confirmation Sampling The work plan proposed drilling one soil boring, SB13, to show that soil remediation has been completed If contamination is encountered, the soil boring would be converted into a vapor extraction well The work plan also proposed the destruction of vapor extraction wells P3, P3A, P313, P3C, P313, EX, VSB3, VSB5, VSB9, VSBI1 Residual contamination detected after the 1990 re-excavation attempt has been under remediation since the vapor extraction system began operation in 1991 The work plan suggested that by March 1993 the majority of all recoverable hydrocarbon vapors would have been removed PHS/EHD does not agree that all recoverable hydrocarbon vapors have been removed, based on more recent data PHS/EHD recommends, at minimum, that vapor extraction continue for an additional quarter, prior to confirmation sampling Three areas of residual contamination have been designated, Area A, Area B, and Area C. Area A encompasses the western pump island (pump island #1),Area B encompasses the eastern tank field,and Area C encompasses the eastern pump island (pump island#3) The proposed soil boring,S1313,would be located in Area B Area A Confirmation soil sampling in July 1992 indicated that contamination was still present as evidenced by soil boring, VS135 The extent of residual contamination was better defined in July 1992, since no contamination was detected in soil borings, SBS and S137 No confirmation soil sampling was proposed in this area PHS/EHD requests a minimum of one confirmation soil borings in Area A. Area B Confirmation soil sampling in July 1992 indicated that contamination was still present as evidenced by soil boring, VSB3, VSB9, and VSB11 The extent of residual contamination was better defined in July 1992, since no contamination was detected in soil borings SB10, S138 and S1312. The area of residual contamination extends approximately 40 feet by 20 feet The proposed soil sample, S1313, is inadequate to characterize this area PHS/EHD requests a minimum of two confirmation soil borings in Area B