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Canepa s Car Wash <br /> 248 East Park Street,Stockton,Calttornia <br /> Third Quarter Groundwater Monitoring Report,July 2002 <br /> Page 3 of 5 <br /> • It is important to note that all wells are drowned, with approximately 20 to 15 feet of water above the top of the <br /> well screens <br /> Concentrations of MTBE in monitor well MW-6 have ranged from <0 5 to 21 gg/L over time, with an general <br /> trend of increasing concentration since April 2001 (Figure 8, Attachment A), the MTBE concentration <br /> decreased slightly from 21 gg/L in April 2002 to 19 pg/L in July 2002 Low concentrations of MTBE have <br /> been sporadically present in groundwater samples collected from monitor well MW-3 Concentrations of <br /> MTBE slightly above the laboratory detection limit have historically been detected in the monitor wells on the <br /> west extent of the site Detections of MTBE appeared first in monitor well MW-4, followed by MW-1, and <br /> most recently MW-7 It is possible that the low concentrations of MTBE represent background concentrations <br /> since they aie at the up-gradient extent of the site <br /> Table 2--Groundwater Laboratory Analytical Results (July 5,2002) <br /> B T E X TPH-G Gasoline <br /> Oxygenates/Additives <br /> Analytical Methods 8021B 8021E 80218 8021B 8015A 8260 <br /> Reporting Litnits--a 05 05 05 10 005 05-13 <br /> Sample 1 D gg/L µg/L gg/L Rg/L mg/L gg/L <br /> 2038-N,IW 1-7/5/02 <0 5 <0 5 <0 5 <10 <0 05 1 9(MTBE) <br /> 2038-MW2-715/02 42 29 56 120 100 <5 0-130 <br /> 7038-MW3-7/5/02 <0 5 <0 5 <0 5 <1 0 0 100 10(MTBE) <br /> 2038-MW4-715/02 <0 5 <0 5 <0 5 <1 0 <0 05 3 7(MTBE) <br /> i2038-MW5-715/02 8,200 13,000 1,500 5,600 570 <50-1300 <br /> 2038-MW6-715/02 <0 5 <0 5 <0 5 <1 0 <0 05 19(MTBE) <br /> 2038-MW7-715/02 <0 5 <0 5 <0 5 <1 0 0 056 2 0(MTBE) <br /> Units Analytical <br /> mg/L=milligrams per liter=parts per million(ppm) B,T E X=benzene toluene,ethyl benzene total xylenes <br /> Ag/L=micrograms per liter=parts per billion(ppb) TPH-G=total petroleum hydrocarbons quantiticd as ga5olule <br /> Gasolme oxygenates/additives=methyl tertiary butyl ether(MTBE), ethanol <br /> tertiary butanol, di-isopropyl ether(DIPE), ethyl tertiary butyl ether(ETBh), <br /> tertiary amyl methyl ether(TAME) <br /> FUTURE WORK <br /> The next quarterly groundwater monitoring event is scheduled for October 2002 Condor is currently preparing <br /> a Work Plan for Additional Groundwater Investigation to further evaluate the vertical and horizontal extent of <br /> groundwater contamination at the site <br /> • <br /> 1 <br /> �1� CONDOR <br />