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• QUARTERLY GROUNDWATER MONITORING REPORT FOURTH QUARTER 2005 QUIK STOP MARKET NO. 132 3555 WEST HAMMER LANE STOCKTON, CALIFORNIA 1.0 INTRODUCTION ATC Associates Inc. (ATC) is pleased to present this report for the Fourth Quarter 2005 groundwater monitoring conducted at the subject site in Stockton, San Joaquin County, California(Figure 1). The site plan (Figure 2) shows the location of the station building, adjacent streets, monitoring wells, and other site-specific features. Sampling this quarter employed low-flow/ low-purge sampling using a peristaltic pump. The monitoring wells have been sampled quarterly to monitor two shallow groundwater aquifers underlying the site. The program scope of work is as follows: • Measure depth to groundwater in site wells; • Analyze groundwater samples for select petroleum hydrocarbon constituents; • Construct groundwater elevation contour maps within the study area boundaries; and • • Compare current and past data. This quarter ATC re-instituted sampling for TPH-G, BTEX, and five fuel oxygenates as approved in an updated letter from the San Joaquin County Environmental Health Department received on November 17, 2005. The existence and degree of petroleum hydrocarbons in groundwater underlying the site is evaluated by (1) the presence of free-floating product and(2) laboratory analysis of groundwater samples analyzed for total petroleum hydrocarbon compounds in the gasoline range (TPH-G), the five fuel oxygenates; tert- Amyl methyl ether (TAME), Methyl Tertiary-Butyl Ether (MtBE), tert-Butanol (TBA), Diisopryopyl ether (DIPE), and Ethyl-tert-butyl ether (ETBE), and benzene, toluene, ethylbenzene and total xylenes (BTEX). 1.1 Performance Bond The performance bond required by the City of Stockton to maintain the monitoring wells was renewed for another year. The new bond will expire on October 2, 2006. A copy of the bond is attached in Appendix D. 2.0 GROUNDWATER SAMPLING On November 30, 2005, in accordance with ATC's field protocols (Appendix A), groundwater samples were collected from on-site groundwater monitoring wells MWAR, MW-2, MW-4, and MW-5. The off- site groundwater monitoring wells MW-9 and MW-10 were not sampled because there was a car parked on them. Groundwater purged from the wells and equipment decontamination water was placed in Quarterly GW Monitoring Report-4th qtr 2005 NVATC Quik Stop No. 132 Quik Stop Markets,Inc. ATC Project No.75.62503.3206 December 16,2005 Page 1 of 4