ARCHIVED REPORTS_XR0004430 - Laserfiche WebLink

Home Browse Search

li 1 Third Quarter Groundwater Monitoring Report September 2003 Boyett Petroleum,419 S.Main,Manteca,CA Page 7 LABORATORY ANALYTICAL RESULTS The groundwater samples were analyzed for benzene, toluene, ethyl benzene, and total xylenes (BTEX) and selected gasoline oxygenates/additives by EPA Method 8260B, and total petroleum hydrocarbons quantified as gasoline (TPH-G) by Method 8015B by Argon. The selected oxygenates/additives included MTBE, ethanol (EtOH), tertiary-butanol (TBA), di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), tertiary-amyl methyl ether (TAME), 1,2-dichloroethane (1,2-DCA), and 1,2-dl-bromoethane (EDB). Laboratory analytical results for the groundwater samples collected at the site on September 30, 2003, indicate that BTEX constituents, gasoline oxygenates/additives, other than MTBE, and TPH-G were not detected at or above the laboratory reported detection limits in the groundwater samples collected from MW-1 and MW-9. MTBE was detected in the groundwater samples collected from MW-1 and MW-9. The laboratory analytical results for the September 2003 monitoring event indicate a large decrease in the concentration of MTBE detected in the groundwater sample collected from MW-1, and an increase in the concentration of MTBE detected in the groundwater sample collected from MW-9 relative to the previous sanpling event conducted in August 2003. The drastic decrease in the concentration of MTBE detected in the groundwater sample collected from MW-1 is directly attributed to the depth of the well's screened interval and current low groundwater conditions present at the site. The laboratory analytical results for the third quarter 2003 quarterly groundwater monitoring event are presented in Table 6, below. A map representing MTBE isoconcentration contours in shallow groundwater is not included in this report due to lack of data. A graph showing MTBE concentrations versus time in monitor wells MW-1 and MW-7 is presented as Figure 9, attached. Historical groundwater monitoring • data, laboratory certificates of analyses, and chain of custody record are also attached. TABLE 6: Laboratory Analytical Results (September 30, 2003) Oxygenates/Additives B T E X TPH-G MTBE Other Oxygenates/Additives Detection 0.5 0.5 0.5 1.0 0.05 0.5 0.5-5.0 Limits: [1 / !tg/L �tg'L µgIL mg/L µg/L ttg/L Analytical Method: 8260B 9260B 8260B 8260B 8015B 8260B 8260B Sample I.D. 3761A-MWI-9/30/03 Q.5 <0.5 <0.5 <1.0 <0.05 35 <0.5-5.0 3761A-MW9-9/30/03 <0.5 <0.5 <0.5 <1.0 <0,05 4.9 <0.5-5.0 Unit Conversions: µg/L:parts per billion(ppb) mg/L:parts per million(ppm) Anal,}tical BTEX=benzene,toluene,ethyl benzene,and total xylenes. TPH-G=total petroleum hydrocarbons,quantified as gasoline. MTBE=methyl tertiary-butyl ether Other oxygenates/additives = ethanol (EtOH); tertiary-butanol (TBA), di-isopropyl ether (DIPS), ethyl tertiary-butyl ether ------n �-•u-�'��+••+�•t•y+�u•c1 ti�ivin�, i,L-WciliVlVculaele(1,L-L�.RJ,and i,�-dioromoerhane(1~;iJfsj '1 4M �� CONDOR