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s I r 1 4 <br /> 30 September 1997 <br /> AGE-NC Project No 95-0144 <br /> ' Page 3 of 3 <br /> As stated in the revised CAP, only low concentratioris of hydrocarbons are present in soil in the <br /> vicinity of USTs No 3 through 6 at a depth of 15 to 25 feet bsg Hydrocarbon concentrations in <br /> groundwater show a decreasing ttend-and-the-impact d round water plume does not appear to be <br /> ' inigiating Installation of �rrnedial system would not cost effective based on the possible <br /> benefits obtained We therefore recommend uati as the remediation method for soil <br /> in the vicinity of formerSTVQ_ 3.Lb iou g ln'6 <br /> The vertical and lateral extent of hydiocarbon-impacted soil in the vicinity of former_USTs No 1 <br /> is limited Impacted soil extends to a depth of less than 20 feet'ksg Ex Qn of impacted so l�can� <br /> ' easily be accomplished using a backhoe of excavator Small volumeof impacted soil may_ <br /> not be —� <br /> reachable by excavation near UST No 1 However, due to the limited`"l�teral.extent,of l�y a small <br /> olunne of impacted soil would be left in place _ <br /> Cost estimates_foaZv -amtion in the vicinity of T o 8 ar similar to air spnargii /vapor <br /> extraction However, on-site treatment of—excavated- sojL_wbuld decrease the overall cost of <br /> excavation The treated soil may also be used as backfill material Due to the rise in giound water, <br /> additional ground water is in contact with impacted soil near UST No 8 However, following <br /> t emoval of the contaminant source by excavation, natural attenuation is recommended as the <br /> iemediation option for ground water Samples collected following <br /> to determine the piedicted effectiveness of natural attenuation excavation should be analyzed <br /> Testing for oxygenating compounds is now required by the <br /> detected, the scope of woik for the site rei ediation may eedE tobechanged If these compounds <br /> dat d <br /> compounds Nvete not detected in giound water samples collected during the August 1997 monitoring <br /> ev ent <br /> LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised b <br /> environmental consultants practicing in this or similar localities The findings were based upon <br /> analytical results provided by an independent laboratory Evaluations of the geologic/bydrogeologic <br /> conditions at the site for the purpose of this investigation ase made from a limited number of <br /> available data points (i e monitoring wells, soil borings) and subsurface conditions may vary away <br /> ' from these data points No other warranty, expressed of implied, is made as to the professional <br /> ieconnmendations contained in this report <br /> ti <br /> r > , <br /> Edianced GeoEn+iron merit ri,Inc <br /> 1 <br />