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10 November 1999 <br /> AGE-NC Project No. 98-0433 <br /> ,. Page 12 of 13 <br /> 5,0. SUMMARY AND CONCLUSIONS <br /> The following conclusions vere drawn from the results of this investigation; <br /> ' Ground water at the site was encountered at approximately 17 to 20 feet bsg. The prevailing <br /> ground water- flow direction in this area'of Jimco is generally toward the north. <br /> tThe most intensely hydrocarbon-impacted soil «vas encountered in the area of the f6rtl7c:r <br /> US'.l's. Soil contamination N,�ith petroleum was limited to depths of 25 feet bsg and the <br /> highest hydrocarbon concentrations were encountered at depths of 10 to 20 feet bsg. <br /> However, MTBE was detected at reduced concentrations in soil collected Froin a depth of 30 <br /> feet bsg near,the former UST arca. The estimated lateral (-Ment of Impacted soil is depicted <br /> ' in F figure 2. <br /> • The highest concentration of dissolved hydrocarbons quantified as TPH-g,".l'PfJ-d and overall <br /> ' BTEX compounds extends northwa-rd of the former UST area. Hydrocarbons were <br /> encountered in the presumed down-gradient direction from the UST to the location of grab <br /> water sample 1314. TPH-g and BT EX concentrations in ground water- decrease east�var:d ita <br /> the area of-well MW-7 and decrease south of Clic former USTs, in the area of well MW-$. <br /> • The lateral extent o#'the dissolved phase plume has been dctermined. higure 4 depicts an <br /> approximate areal distribution of impacted ground water. 4 <br /> ' 6.0. 12ECONI NIENDA'ITONS' <br /> Based on the results of this investigation, .AGE recommends the following. <br /> 1 <br /> • Quarterly monitoring at the site should be initiated. <br /> e Analytical data from the initial site assessment indicates,that remediation of soil .and/or <br /> ground water will be required at the site. 1�-ftorts to create a Corrective Action Plan (CAP) <br /> should be initiated. The CAI' should include rcinediatian feasibility studies (e.-. in-sim air <br /> ' l)rli"glll l:)Ilot (t.5t. Soil \''?poI" C NIractlon. Sr)il Exec ilfion 111d brc)-onhanced rel ccflatton or <br /> attenuation) to dcterrnin . -IpproLite rcm)that options for the site. <br /> Advanced Gcor?nvirouuncnrar, 111c. <br />