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' 3 0 RESULTS AND DISCUSSION This section presents a discussion of the third quarter 1999 monitoring event, and a summary of historical data 3 1 Data Validation The laboratory report provided by Quanterra was reviewed by Dames & Moore's data validation group in order to insure that the reported data results are accurate Results of the Dames & Moore QA/QC of the data are included in Appendix B All data were determined to be acceptable for use, with the following qualifications • A hydrocarbon pattern outside the TPH-D range was observed in the laboratory QC samples as well as all pro}ect samples These hydrocarbon peak pattern-, were not within the TPH-D range Therefore, the patterns were not identified as TPH-D or quantitated These patterns are not native to the samples and are tentatively identified as laboratory contamination on the sample chromatogram-, attached in Appendix B • In contrast, the peaks present within the TPH-D range in samples DMW-1, DMW-2, DMW-3, and DMW-4 do not represent hydrocarbon patterns and do not match the diesel standard Consequently, the results were identified as unknown hydrocarbons To further determine the nature of these peaks, an additional analysis was performed on sample DMW-3 using the Northwest Cleanup Procedure The Northwest Cleanup ' Piocedure includes an acid wash, which removes non-petroleum hydrocarbons Results of the Northwest Cleanup Procedure analysis indicate that the unknown hydrocarbon form the original analysts was removed, suggesting that the observed hydrocarbons are ' not petroleum hydrocarbons + These peak patterns of samples from DMW-6 and DMW-7 appear to represent weathered diesel The chromatographic patterns of samples DMW-6, DMW-60, and DMW-7 do not exactly match the diesel standard, and results were identified as unknown hydrocarbon by the laboratory Since the surrogate QC criteria were slightly exceeded in the TPH-D analysis of samples DMW-6, DMW-60, and DMW-7, the reported concentrations should be considered estimated 3 2 Groundwater Levels ' Groundwater was measured to be approximately 39 feet below ground surface on September 9, 1999 Groundwater levels decreased approximately 3 7 feet between June 1999 and September 1999 The direction of groundwater flow in September 1999 was towards the north-northeast, as illustrated in Figure 3 Groundwater level data recorded since July 1987 is presented in Table 2 Groundwater levels appear to have reached a maximum elevation of approximately 35 feet bgs in June GAMES&MOORE S 1 VAFPIREPORT1991 101 doc