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S E C O R <br /> • There are discrete peaks in the diesel range for the samples from MW-24, QCDUP-2, MW-26, <br /> and MW-44, atypical for diesel fuel. <br /> There are discrete peaks in the motor oil range for the sample from MW-26, atypical for motor <br /> oil. <br /> Validation issues with report number 60756: <br /> Values reported for p,m-xylene that are below the MRL should be considered estimates. Values <br /> for p,m-xylene are reported to the lower CRDL of 0.50 µg/L. <br /> Percent recovery for mercury in the MS/MSD was out of QC range indicating a lack of accuracy <br /> in reporting. RPD values were in range, indicating a degree of precision. In addition, both <br /> percent recovery and RPD values were in range for mercury in the LCS/LCSD; thus, reported <br /> values for mercury are considered valid. <br /> Percent recovery for cadmium was out QC limits in the LCSD. RpD values were in range in the <br /> LCS/LCSD indicating a degree of precision. Additionally, both percent recovery and RPD <br /> ranges for cadmium were within QC limits in the MS/MSD; thus, reported values for cadmium <br /> are considered valid. <br /> Validation issues with report number 60774: <br /> Values reported for p,m-xylene that are below the MRL should be considered estimates. Values <br /> • for p,m-xylene are reported to the lower CRDL of 0.50 µg/L. <br /> The method reporting limit for ethanol was increased due to the presence of an interfering <br /> compound for sample MW-53. <br /> The method reporting limit for chloromethane was increased due to the presence of an <br /> interfering compound for sample MW-53. <br /> 4.5 First Quarter 2008 SPH and Hydrocarbon Concentration Trends <br /> 4.5.1 Shallow Zone <br /> The following sections summarize trends for detected petroleum hydrocarbons, fuel oxygenates, <br /> and observed SPH for shallow (A-Zone) groundwater beneath the Site. <br /> 4.5.1.1 SPH <br /> Measurable SPH or SPH-sheen has historically been observed in shallow, A-Zone wells <br /> MW-10, MW-21, 2AMW-14, DPE-2, DPE-5, DPE-11, and DPE-12. Due to the quantity and <br /> viscous nature of the SPH, and the presence of emulsified SPH and groundwater in some of <br /> these wells, the depth to groundwater/SPH interface and corresponding SPH thickness have <br /> historically been difficult to accurately measure. This is evidenced by the inability to obtain SPH <br /> thickness measurements from wells 2AMW-14 and DPE-4 in December 2002, from well DPE-8 <br /> in February 2004, and from wells DPE-8 and DPE-10 in May 2005. Variations in measured <br /> • depth to water/SPH and SPH thickness are apparent in several of these wells from quarter to <br /> quarter. This may also be attributed to seasonal fluctuations in groundwater levels. <br /> 1 Q08QSSRQRSRQMR.Fina1.doc 20 April 30,2008 <br /> 77TW.26397.42.1307 <br />