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Ir <br /> 08 October,1999 jf <br /> AGE-NC Project No 951-0121 <br /> Page 5 of 6 ` <br /> t , <br /> (Figure 3) t <br /> • The' eneral ground water gradient in the area bound by-wells V W-3 V W 4o <br /> g t uthwest(Figure <br /> `8 was calculated to be approximately 0 001'ftlft and directed towards e s <br /> 4},this gradient was contrary to the ground water flow direction observed in the surrounding <br /> area bound by wells MW-1, MW-2, MW-3, MW= and MW-7 <br /> Due to the low gradient at the site, slight variations in ground water measurements'or <br /> • round water could greatly modify ground water <br /> changes of recharge/discharge of the local g <br /> i flow direction , <br /> I by data obtained at the <br /> A long term trend of increasing ground water elevations is indicated <br /> site since February 1991 <br /> • Wells VW-3, VW-4, VW-6 and VW-8 yield data representative of shallow ground water <br /> conditions <br /> • The elevated petroleum hydrocarbon`concentrations detected in water samples collectedfrom <br /> wells MW-1,MW-2,1'``1W-3 and MW-7 (screened between 25 feet and 53 feet bs suggest <br /> near the dissolved petroleum hydrocarbon ",core <br /> that these wells may be screened within or <br /> area" ofthe plume I ` <br /> • It is no that the concentration <br /> sof dissolved petroleum hydrocarbons and the ground <br /> r extraction <br /> water flow direction and gradient differ between the shallpw"completed vapWells (MW-1, <br /> I V W-4 V W-b and V W-8) and the deeper completed monitoring f <br /> wells (VW-3, , , <br /> MW_2, MW-3 and MW-7)that surround the vapor extraction wells <br /> • r The, -impactedhorizontal extent of petroleum hydrocarbon ground water is not delineated <br /> north, northwest and west of MW-7 and northeast of MW-4 <br /> " <br /> t <br /> 5,0. RECOMMENDATIONS , <br /> _ Based-upodata collected from the site in June 1999, AGE recommends <br /> n <br /> Proceed with additional feasibility study activities upon UST Cleanup Fund pre-approval as t <br /> outlined in'the Additional Remedial InvestlgationJFeasibtllty Study i3'ork Plan, dated 03 <br /> August 1999 and'approved by the PHS-EHD by letter dated 01 September 1999 <br /> ` r I ` " '' �� round water samples to address and <br /> • Preparation of a work plan for the collection of grab g <br /> rocarbon plume north, northwest and west of MW-7 <br /> delineate the dissolved petroleum hyd <br /> and northeast of MW-4w <br /> Continuation of quarterly monitoring, the next event should be scheduled for October 1999 <br /> fti Advanced GeDEnwonmenta1,Inc <br /> I r I <br />