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r KLEINFELDER o TPH concentrations ranging from .28 to 1.23 rng/I were reported in samples from all eight monitoring wells during the February 1988 sampling round. No detectable concentrations of TPH have been reported in samples from MW-4, MW-6,and MW-8 on any other sampling date. o TPH concentrations ranging from .26 to .87 mg/I were reported in samples from five of the wells(MW-1, MW-2, MW-3, MW-S, and MW-7) on the May 1988 sampling round. The highest TPH concentrations were detected in - samples from MW-I and MW-7. The hydrocarbons were identified as an "unknown hydrocarbon mixture" by the analytical laboratory. This mixture , was quantified as either gasoline or diesel by the laboratory in order to report"TPH concentrations." The chromatograms;obtained from the laboratory using a FID detector during the analysis of these samples,are presented in Plates 16 and 17. Chromatograms for fresh gasoline and diesel "standards" are also presented on Plates 16 and 17 for comparison. These chromatograms indicate that the total petroleum hydrocarbons detected in May 1988 have a different character than the fresh gasoline and diesel standards. The retention times and relative amplitudes of the peaks in the May 1988 chromatograms do not correlate well with either standard. The hydrocarbon could be weathered gasoline, gasoline constituents or another hydrocarbon. Additionally, chromatograms for the samples from MW-4 and MW- 6 Jo not resemble the chromatograms for the other sampIcs (except MW-8). The peaks on these chromatograms are lower, and the laboratory reported no detectable concentrations ` of TPH in these samples. me detection limit for TPH in this study is .10 mg/1.] The chromatograms for the sample from MW-8 and the sample blank do not exhibit the same character as the other chromatograms. Therefore, there does not appear to be evidence for cross-contamination during transport or analysis. o TPH concentrations reported for the three samples collected from MW-1 in May 1988 ranged from none detected (detection limit = .10 mg/1) to .87 mg/i. Chemwest used a methylene chloride extraction and detected.31 mg/1 and .87 mg/I TPH in the blind duplicate samples submitted from MW-1. .--------_--__Enseco used-a Freon-extraction and-detected no TPH above the detection- limit etection limit of.10 mg/l. Both analytical laboratories are EPA/State certified. The . reason for this discrepancy is not known. 113-88-908 10