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Environmental <br /> Mr Harlin Knoll Resources <br /> 27 September 1999 Management <br /> Page 2 <br /> • <br /> • Total Petroleum Hydrocarbons (TPH, gasoline range) by US <br /> Environmental Protection Agency (USEPA) Method 8015 modified, <br /> • TPH (diesel range) by USEPA Method 8015 modified, and <br /> • Volatile organic components of petroleum fuels - benzene, <br /> ethylbenzene, toluene and xylenes (BTEX), fuel oxegenates (methyl <br /> tert-butyl ether [MTBE], tert-amyl methyl ether [TAME], 2-Methyl-2- <br /> Propanol [TBA], dlisopropyl ether [DIPE], and ethyl tert-butyl ether <br /> [ETBE]), and 1,2-dichloroethane (1,2-DCA) - by USEPA method 8260 <br /> Monitoring Results <br /> Based on the sampling results presented in Tables 1 and 2, Catellus/ERM <br /> have concluded that site conditions do not appear to have changed <br /> significantly from those observed during previous monitoring This <br /> conclusion is supported by the discussions provided below for the <br /> • different compound classes <br /> TPH/BTEX <br /> As in past sampling events, TPH as gasoline and BTEX compounds were <br /> detected in ground water samples The magnitudes of the July 1999 TPH <br /> and BTEX detections are comparable to those of recent historical <br /> detections As with previous sampling events, at both sites, the highest <br /> detections are associated with the wells located in the immediate vicinity <br /> of the former tanks (MW-5, MW-1A, and MW-2A) TPH and BTEX <br /> detections decrease dramatically in nearby wells, indicating that the <br /> extent of affected ground water is limited These results confirm the <br /> historical data indicating that the plumes are not migrating Historical <br /> trend analysis indicates that TPH and BTEX concentrations have <br /> decreased significantly over time <br /> Oxygenatesll,2-DCA <br /> As summarized below, limited data exist regarding oxygenate and 1,2- <br /> DCA occurrence patterns in ground water at the site However, the <br /> available data support the conclusion that significant impacts to ground <br /> water quality are generally limited to the immediate vicinity of the <br /> former storage tanks <br />