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. WEIGHT OF VOC'S=CF x {VAPORI x 10-6 x 100 mol/wt 379 cf/mole =4 978 x 106 fl x 1,500 10-6 x 100 mol/wt 379 cf/mole =7 467 x 1O'lbs 3 79x 102 = 1970 lbs 5.0 GROUNDWATER MONITORING 5.1 Monitoring Procedures Groundwater monitoring took place on December 4, 1996 The depth to groundwater was measured in all six monitoring wells, but not in VE-1 "deep", which has been consistently anomalous Depth measurements were recorded on the Well Monitor Report (Appendix C) Prior to sampling, MW-5 was purged of approximately 3 gallorfs Two 40-m1 sample vials were collected from MW-5 and were labeled and placed in a cooled ice chest for later delivery to Sequoia Analytical in Sacramento The laboratory report and chain-of- custody form are included in Appendix B 5.2 Depth to Groundwater The normal seasonal rise in the water table was observed during the quarter (Table 1) A rise of approximately 2 feet took place during the quarter y 5.3 Groundwater Gradient and Flow Direction Table 1 illustrates a return to more typical conditions since the third quarter, when three anomalous conditions were encountered Those changes were described in the third quarter report With the return to normal conditions, the strong southeast-trending trough in the groundwater gradient has reappeared (Figure 6) Hence, the groundwater "high" that appeared to be centered around the deep extraction well in the third quarter has not been confirmed, and may therefore have been due to either observational error or some unexplained short-term phenomonon 5.4 Groundwater Contamination As in the previous six quarters, contaminants were detect6d in MW-5 (Table 2) The benzene and TPH-g concentrations reached a peak in May, when the water table was high, but declined as the water table dropped in the third quarter Concentrations remained almost the same in the fourth quarter _ 5