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Co-extraction Well Installation Report November4, 1997 <br />' EW-3 as ns - -4 <br /> w installed Ill the northeastern portion of the impacted area and co extraction well EW <br /> was installed in the southeastern portion of the Impacted area <br /> The four new co-extraction wells are each constructed of 4%2 -inch-diameter, schedule 40, poly- <br />' vinylchlonde casing, and are screened with 0 020-Inch perforations The wells were all drilled <br /> to 30 feet bgs The lower 5 feet of each well (30 to 25 feet bgs) is constructed of blank <br /> (unscreened)PVC which acts as a clay-silt-sand sump In EW-1,the screened interval extends <br />' from 25 to 61/2 feet bgs with an upper blank portion extending from 6l/2 to 1 foot bgs In EW-2, <br /> EW-3 and EW-4, the screened Interval extends from 25 to 10 feet bgs with an upper blank <br /> portion extending from 10 to 1 foot bgs <br />' The co-extraction well construction details, Including the borehole diameter, depth, casing <br /> diameter,screened Interval,filter pack interval,and surface seal interval are presented on Table 1 <br />' and included on the well logs(Appendix B) The procedures for groundwater/air co-extraction <br /> well installation are presented in Appendix C <br /> 2.3 Well Locations <br /> ' The horizontal locations of the co-extraction wells (EW-1, EW-2, EW-3 and EW-4) at the site <br /> were measured by representatives of OST on August 8, 1997 Because of air and groundwater <br /> pumping operations,topographic elevations for groundwater elevation measurements were not <br /> . obtained for the co-extraction wells <br /> 2.4 Laboratory Analyses <br /> tThe four soil samples were submitted to the laboratory and analyzed by the following methods <br /> • <br /> TPI-Ig utilizing EPA Method 8015M <br /> • BTEX and MTBE utilizing EPA Method 8020 <br /> t3.0 QUALITY ASSURANCE/QUALITY CONTROL <br /> The following sections present information pertaining to the field and laboratory quality <br /> ' assurance/quality control (QA/QC) measures implemented during the field and laboratory <br /> procedures <br /> ' 3.1 Field QA/QC <br /> ' All field equipment was cleaned and decomaminated prior to being Introduced into the sampling <br /> environment A new sampling tool or a precleaned, decontaminated sampling tool was used at <br /> each sampling point Decontamination was accomplished by steam cleaning or washing with <br /> ' a cleaning solution and then double rinsing with fresh water to remove particles and/or <br /> groundwater which may have adhered to the surface of the sampling tool <br /> ' OST <br /> coexwell rpt 3 <br />