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S E C 0 R oxygenates (MtBE, TAME, di-isopropyl ether [DIPS], ethyl tertiary butyl ether [EtBE], TBA), 1,2-dichloroethane (1,2-DCA), and ethylene dibromide (EDB) by Environmental Protection Agency (EPA) Method 8260B. Results are discussed below and are summarized in TRC's Quarterly Monitoring Report, July through September 2005 dated October 20, 2005, which is included in Attachment 1. DISCUSSION During the third quarter 2005, depth to groundwater ranged between 7.54 and 12.09 feet bgs, which was in range of historical levels (approximately 5.5 feet to 13.5 feet bgs). The direction of groundwater flow was reportedly variable this quarter. Localized groundwater flow beneath the site was relatively flat; however, beneath adjacent properties to the southwest, the direction of groundwater flow was southerly to southwesterly. Over the last two years of groundwater sampling, the direction of groundwater flow has predominantly been southerly, with variations in groundwater flow to the southwest to southeast. During the third quarter 2005, relatively low levels of GRO and MtBE were detected in the site wells. GRO was detected in wells MW-3, MW-4, MW-6, MW-8 and MW-9 up to a maximum concentration of 120 micrograms per liter (pg/L). MtBE was detected in each of the site wells except for wells MW-4, MW-10 through MW-12, and MW-20 up to a maximum concentration of 69 pg/L, with the highest concentrations detected in on-site wells MW-3 (59 pg/L) and MW-9 (33 pg/L), and in off-site upgradient well MW-8 (69 pg/L). Other fuel oxygenates were not detected in the site wells this quarter, with the exception of a concentration of TBA in well MW-3 (290 pg/L) and a relatively low level of �— TAME in well MW-8 (0.55 pg/L). Evaluation of historical groundwater data indicates the presence of a large dissolved plume, consisting predominantly of MtBE, extending from beneath the site to the south- southwest. However, concentrations of MtBE in the majority of the impacted wells have decreased over time, with the exception of those within MW-14, which have fluctuated within historical levels. The analyte was detected during the initial sampling of new wells MW-22, MW-23, and MW-24 at levels below the primary maximum contaminant level (MCL) of 13 pg/L. Review of historical analytical results for other fuel oxygenates indicate that with the exception of occasional detections of TAME and TBA, the majority of the wells (MW-1, MW-2, MW-4, MW-5, MW-11 through MW-24) have consistently reported non-detectable concentrations of other fuel oxygenates. Wells MW-3, MW-6, MW-8, MW-9, and MW-10 have reportedly contained TAME and TBA over recent sampling events, with the highest concentrations of TBA most consistently detected in well MW-3 at a historical site maximum concentration of 640 pg/L (August 2004). CHARACTERIZATION STATUS Contamination in soil beneath and downgradient of the site has been adequately delineated. The extent of the dissolved plume is delineated by historically non- detectable concentrations of petroleum hydrocarbons in well MW-21 to the southwest, and by well MW-12 to the west. The dissolved GRO and BTEX plumes have been delineated across the site. Contamination in groundwater, specifically MtBE has been delineated to low levels I:1ConocoPhi11ips%Reta11 sites1111951Reports\QSR&QRPS 2005\1 1195 QSR QRPS 3Q051.doc