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' Process Controls <br /> EMCON will be extracting from four groundwater monitoring wells (MW-1, <br /> MW-2, MW-3, and MW-4) at the rate of approximately l gpm per well The <br /> treated groundwater will be discharged through two reinjection wells (RW-1 <br /> ' and RW-2) at the approximate rate of 2 gpm per well (see Figure 1) Flow <br /> of groundwater from the extraction wells to the remediation system will be <br /> manually controlled by flow regulating valves A high level switch will shut <br /> ' off the system in case there is a pipe failure A high level switch in the <br /> air/water separator will also shut off the system if the extracted groundwater <br /> is highly entrained <br /> ' 7 Groundwater analysis <br /> ' Historical groundwater analytical data are in Attachment B Groundwater <br /> quality data is contained in Attachment C <br /> ' B. Site Hydrogeology <br /> 1 Depth to groundwater <br /> Attachment D contains the historical groundwater elevations at the site Depth <br /> to on-trite groundwater ranges from 34 56 to 26 04 feet below ground surface <br /> �i (bgs) <br /> ' 2 Direction and gradient of groundwater flow <br /> Historically, the gradient of groundwater flow has averaged approximately <br /> ' 0 006 foot per foot The direction of groundwater flow on site has varied over <br /> time from north-northeast to southwest and southeast Groundwater flow at <br /> the site has been to the southwest and southeast during the past four quarters <br /> of monitoring <br /> 3 Vertical and lateral extent of pollution <br /> Between August 1988 and November 1991 a total of 22 soil borings were <br /> drilled to Investigate the lateral and vertical extent of petroleum hydrocarbon <br /> ' impact to soil and groundwater Nine of these boil borings were subsequently <br /> converted to groundwater monitoring wells (MW-1 through MW-9) Boring <br /> logs and well completion details are included in Attachment E The impacted <br /> boil is in the range of 10 to 25 feet bgs, the lateral extent of petroleum <br /> hydrocarbon-impacted soil is estimated approximately to be 120 feet by <br /> 120 feet Analytical result~ of soil samples collected during exploratory soil <br /> boring% are attached (see Appendix F) The total lateral extent of groundwater <br /> tiAC/p}2\2520\25201000 ICI 94 Ift.8 3 Rev 0 tieptembLr 15 1994 <br />