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Workplan for Interim Remediation &41h Quarter 2000 Groundwater Monitoring Report Former Moore Petroleum Bulk Plant,5491 F Street, Banta,California ✓ Page 2 of 9 Apex was in the process of performing a dual-phase remediation pilot test at the site, when the groundwater analytical results from the October 27, 2000 sampling event were received. Based on the presence of MTBE in the Rhodes well, it was Apex's and the County's recommendation to forgo the pilot test and install an interim remediation system at this site as soon as possible. This report is based, in part, on information obtained from Moore Petroleum, and is subject to modification as newly acquired information may warrant. Background information can be found in Apex's Workplan for Limited Subsurface Investigation dated April 14, 2000. GROUNDWATER MONITORING Groundwater Levels On October 27, 2000, Apex personnel collected water-level measurements from all twelve existing groundwater monitoring wells (MW-1, MW-2, MW-3, MW-4A, and MW-5 through MW-12). All groundwater elevations were measured to the nearest 0.01 foot, referenced to the surveyed top-of-casing elevations, and conducted according to the Apex standard operating procedures (SOP) included as Appendix B. Liquid-level measurements collected to date by Apex are summarized in Table 1. -Figure 3 is a groundwater contour map of the shallow water- bearing zone on October 27, 2000 and shows groundwater flow to be towards the northeast at an approximate hydraulic gradient,of 0.0035 foot/foot. Groundwater Sampling and Analvsis On October 27, 2000, Apex personnel collected groundwater samples from all twelve existing monitoring wells and the off-site Rhodes well. The samples were submitted, under chain-of- custody, to CLS of Rancho Cordova, California. All samples were collected according to the Apex SOP included in Appendix B. All groundwater samples were analyzed for concentrations of total petroleum hydrocarbons, as gasoline, (TPHg), and TPH as diesel/kerosene (TPHd)by modified EPA Method 8015; and benzene, toluene, ethylbenzene, total xylenes (BTEX) by EPA Method 8020; di-isopropyl ether (DIPE), ethyl tertiary butyl ether(ETBE), MTBE, tertiary amyl methyl ether(TAME), and tertiary butyl alcohol (TBA), collectively the `five oxygenates', by EPA Method 8260. The laboratory analytical report and chain-of-custody form are included in Appendix C. Analytical results collected by Apex to date are summarized in Tables 2 and 3. All purged and recovered liquids are stored temporarily on site in Department of Transportation- approved, 55-gallon drums pending removal from the site by a licensed hauler to an appropriate disposal facility.