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aq_ <br /> 06 May 1999 Y E <br /> y AGE-NC Project'No. 08-0'536 <br /> Page 4 of 4 - 4 ' <br /> 2: <br /> y <br /> Y..i' , R K. <br /> Samples (S2-13Y and (S3Y 17 5} contained concentrations of MTBE at7 8'and 12 micrograms per <br /> iciIogram(ug/kg),respectively:TBA;-DIPE, ETBE, and`TAME were not detected'`at concentrations <br /> a above tha reported limit`s in'(S2-T3)'and(S6-1-7.5). Samples-(S5 17),and(S4=18)had concentrations .� <br /> F ` of MTBE at 230 and.14,000 ug/kg;respectivelk, F _ ' <br /> - TPH g .was .detected m stockpile samples (SP 3-2), (SP-3 3); (SP 3 5), ;and " SP 3 6 at <br /> ) <br /> concentrations:ranging from.1'.4 to 2I0 mg/kg fTPH d was detected-in"all samples,-at concentrations <br /> ranging from- 5.9 to 220 mg/kg-.-,Toluene was defected iri:{SP 3-3) at`,a concentratson of 0:04.mg/kg " <br /> '_Samples(SP-3=2)and(SP 3-3)'contained concentrations ofMTBE at 320 and 13 ug/kg Additionally r - <br /> samples. (SP-3-2) and (SP-3`=3}3.contamed TBA at concentrations' of_7;800 and 1,500;ug/kg, , <br /> :.respectively. Analytical,results of soil samples,are summarized in.-Table Z and`2. The=laboratory <br /> " r <br /> reports and chain-of'custody forms are included in.Appendix AL" <br /> &o". F DISCUSSION. s , - - <br /> t,. ; S -J P,- moo+- ,':c (': y -' h � :s - ,_ y .1 � - ,-• �� - <br /> The analytical results of samples collected during the 19 zFebruary 1999 excavation indicate <br /> significant MTBE impact to_soil at-18'feef b9g'near the former.dispenscrisland an'a beneath former <br /> gasoline UST.#1.Laboratory notes indicate the presence of hydrocarbons higher in`molecular weight i <br /> r than diesel detected in=several'sarriples collected from the stockpile:The"unknown" 1;000-gallon <br /> -' UST #3 'may.have been awaste=oil UST or possible'a motor oiI.UST based on this analytical <br /> evidence. The vertical 'and:lateral -extent-of impacted-soil'is not' known at'tls 'tiirie Further "A <br /> 6 - i - - <br /> x subsurface investigation is necessary to determine- he extent of the iiripact ;� f <br /> 17 <br /> o- ' r <br /> 74 <br /> 7 0 RECOMMENDATIONS <br /> J ¢.. <br /> :i <br /> ' 'Based'upon the'detection of MTBE-at concentrations as great as. 14,000.ug/kg,in"soil.at-depths as� <br /> great::, -18 feet bsg,__AGE recommm�ds-fur-th r subsurface investigation:at the site.to_determine the <br /> MTBE impact to soil and groundwater Ground water is approximately 70 feet bsg;but can varydue " <br /> - to.seasonal_rairi fail and locaI agricultural-watering practices:The groundwater flow-direction-orisite. . <br /> , _ . <br /> is inferred to have'a southerly direction AGE'recommends gone'soil bonng advanced;to ground = - <br /> a total.depth of approximately 70 feet bsg;near the former UST,area Four borings <br /> advanced northwest north;northeast ,and <br /> south of the=former,UST�area 'to determine the lateral <br /> extent of MTBE impacted soil. Refer to Figure 2 for proposed boring'locationst _ <br /> s <br />,7L <br /> 41 <br /> ' a F Advanced GioEnvi`ronmental,Ine <br /> 9 • .N - -ro. •1-ter+ �.. { �.• r _ _-� a-y _ 6 f .., _ _ <br />