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SECTION 5.0 RESULTS AND DISCUSSIONS 5.1 GROUNDWATER SAMPLING RESULTS 5.1.1 Vertical Groundwater Sampling Results The results of the groundwater quality parameters and inorganic compounds (nitrogen as nitrate and sulfate) for wells MW-13, MW-14 and VM-2 are presented in Table 5-1 The specific conductivity, temperature, and turbidity results were consistent with typical groundwater quality parameters The pH results were low in each well (less than 4 5) Lower pH measurement may have been due to meter calibration errors Dissolved oxygen concentrations were measured in water samples brought to the surface, the results were consistent with dissolved oxygen concentrations in surface water bodies rather than insitu oxygen concentrations in groundwater (typically less than 5 mg/L) The saturated oxygen concentration in water (i.e , water that is exposed to air) with a water temperature between 17 and 18°C is approximately 8 mg/L, which is similar to the measured dissolved oxygen concentrations from the three wells (7 7, 8 34, and 8 16 mg/L, respectively) The inorganic results for nitrogen as nitrate ranged from 3 4 to 6 8 mg/L, for sulfate ranged from 18 to 30 mg/L, and were consistent with anoxic to anaerobic conditions The discrete vertical groundwater analytical results for TPH-g, BTEX, and MTBE for wells 1. MW-13, MW-14, and VM-2 are presented in Table 5-2 and are graphically shown on Figure 5-1 The analytical laboratory reports, including chain-of-custody documentation, are provided in Appendix E The results for well MW-13 show an increase in TPH-g and benzene concentrations in groundwater with depth from 45 5 to 55 5 feet bgs (from 94 to 540 µg/L, and 36 to 240 µg/L, respectively) and increase from 540 to 1,100 pg/L and 240 to 430 4g/L, respectively, in groundwater samples collected from 55 5 to 66 feet bgs The analytical results are not 1 significantly different at 75 and 85 feet bgs in well MW-13 (490 to 560 µg/L, and 200 to 240 µg/L, respectively) A concentration of MTBE of 12 µg/L was detected in the groundwater sample collected at a depth of 45 5 feet bgs Historically, the highest concentrations of TPH-g and BTEX in groundwater in well MW-13 were detected in 1998, when groundwater was at a depth of 48 6 feet bgs (see Table 3-2) The highest concentrations of TPH-g and BTEX in soil ' were observed at depths of 50 and 55 feet bgs, respectively(see Table 3-1) The results for well VM-2 did not change significantly with respect to concentrations of TPH-g and benzene in groundwater with depth from 46 5 to 59 5 feet bgs (29,000 to 30,000 µg/L, and 10,000 to 9,000 µg/L, respectively) Concentrations of MTBE were not detected in the groundwater samples collected from VM-2 The historical high concentrations of TPH-g and benzene in VM-2 (72,000 and 28,000 µg/L, respectively) were detected in 1997, when groundwater was at an estimated depth of approximately 56 feet bgs (Table 3-1) The highest S IPROJ141040100041SHOP101S140P10SA DOC 5-1 URS Greiner Woodward Clyde