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4 Mr. Jeff Goold - 3 - 14 February 2008 <br /> Shell Stockton Terminal . • <br /> be conducted for total petroleum hydrocarbons as gasoline (TPHg), benzene, toluene, <br /> ethylbenzene, and xylenes (BTEX), methyl tertiary butyl ether (MTBE), and TBA. No <br /> groundwater sampling and analysis is proposed for the DPE pilot test. <br /> Pressure differences and groundwater levels will be measured in adjacent wells. Groundwater <br /> pumping rate, dilution air flow, and total extracted groundwater volume will be measured at the <br /> extraction wells. Shell proposes to prepare a report summarizing results and findings at the <br /> end of DPE testing. However, more than one report may be submitted depending on the <br /> actual pilot test implementation schedule. <br /> Our comments are presented below. <br /> 1. The IRAP proposes no laboratory analysis of groundwater extracted either during <br /> preliminary de-watering or the pilot test. This omission appears to present a missed <br /> opportunity to collect groundwater data for long-term groundwater treatment system <br /> design. However, the 1 February 2008 Groundwater Monitoring and Remediation Report <br /> (Fourth QMR) documents groundwater monitoring results from 1991 to present in the SAs, <br /> Shell will collect depth discrete groundwater samples during drilling, and Shell intends to <br /> truck the effluent to its Martinez refinery. Thus, Regional Water Board staff will assume that <br /> Shell will refer to the historical groundwater monitoring results for data that may be needed <br /> to design a future system for long-term remediation. <br /> 2. The Fourth QMR documents that the laboratory used a silica gel cleanup procedure during <br /> analysis of total extractable petroleum hydrocarbons (TEPH) via EPA method 8015 . The <br /> resulting concentrations both decreased and increased relative to historical trends. <br /> Regional Water Board staff do not allow the use of silica gel cleanup before analysis. Silica <br /> gel cleanup is a tool that is used to separate polar organics from normally non-polar <br /> petroleum hydrocarbons in water samples, but silica gel can also filter out non-polar target <br /> compounds potentially resulting in unrepresentative laboratory results. In addition, the polar <br /> organics may be early breakdown products of petroleum hydrocarbons and should not be <br /> ignored. Shell may not use this procedure in future analysis. <br /> 3. We concur that with Shell's responses during the November and December 2007 <br /> teleconferences regarding limiting site cleanup until site use changes, and that the pump <br /> lodged at the bottom of MW-10 does not constitute enough of a hindrance to delay the pilot <br /> test. However, by omitting final estimates for alternate cleanup technologies, including <br /> excavation and SVE/AS, Shell has failed to demonstrate that these technologies are <br /> financially infeasible and should be eliminated from consideration as remedial alternatives. <br /> If DPE proves to be technically infeasible, we may require Shell to follow up with the <br /> evaluation and possibly pilot testing of these remedial options. <br /> 4. The IRAP and the WP-FS have described the proposed pilot test in sufficient detail to <br /> warrant implementation. Shell stated in the IRAP that the DPE pilot test will be scheduled <br /> once the schedule for installation and development of the proposed monitoring wells is <br /> known. Therefore, by 7 March 2008, please submit a time schedule to 1) install the wells, <br /> 2) conduct the pilot test, and 3) submit a report describing the well installations and pilot <br /> test findings. <br />