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Former Tank Site #2, The analytical results of ground water samples from the five monitoring wells located at Former Tank Site #2 are ' summarized in Table 4-4 Of the five monitoring wells, only wells MW-1A and MW-2A commonly exhibited detections of TPH and/or BTEX compounds during the monitoring period The first sample collected from MW-3A exhibited low concentrations of BTEX compounds that were not confirmed by subsequent sampling events In addition, one sample collected from MW-4A exhibited low TPH (0 072 mg/1) and xylene (0 001 mg/1) concentrations in November 1994, previous and subsequent sampling events associated with this well did not result in detectable TPH/BTEX concentrations One ground water sample collected from well MW-5A exhibited a low xylene concentration (0 002 mg/1) These three sample results are considered anomalous and are assumed to be unreflective of current site conditions associated with these well locations Hydrographs illustrating changes in benzene and TPH concentrations in ground ' water samples collected from monitoring wells MW-1A and MW-2A are shown on Figures 4-7 and 4-8, respectively Chemical trends associated with wells MW-1A and MW-2A are discussed below TPH as gasoline (TPHg) detections in samples collected from MW-1A decreased significantly over the monitoring period, the highest concentrations were detected during the period from 1992 to 1993 TPHg detections in samples collected from MW-1A ranged from 50 mg/1 (April 1993) to 2.8 mg/l (May 1994), TPH detections in samples ' collected during the last two sampling events are less than 5 mg/1 TPH concentrations in samples collected from well MW-2A have fluctuated since inception of monitoring, most of the samples exhibited TPH concentrations less than 1 mg/1 TPH as diesel (TPHd) detections are somewhat lower (ranging from 71 mg/1 to nondetect in MW-1A and from 16 mg/l to nondetect in MW-2A) and exhibit 1 similar trends to TPHg BTEX detections followed similar detection patterns Benzene ' concentrations exceeded MCLs in samples collected from MW-1A and MW-2A Toluene, ethylbenzene and xylene exceeded MCLs in several samples collected during 1992 and 1993 from MW-1A, however, these compounds did not exceed MCLs in any samples collected from MW-2A. Benzene detections in MW-1A samples ranged from 16 mg/1 (April 1993) to 0 47 mg/l (May 1994) Benzene detections in MW-1A samples collected during the last sampling event were less than 1 mg/l. Benzene concentrations in MW-2A samples ranged from a maximum of 0 036 mg/l (May 1994) to nondetect (several sampling events) Ethylene dibromide and organic lead were not detected in any ground water samples collected from Former Tank Site #2 Total lead w 4-8