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margin of this deposit (Figures 4 and 9) CPT calculations yielded h, values of 1 x 1015 cm/sec in interbedded silty mudstone along the channel margin 3 3 Depth to Groundwater Table 2 provides all depth-to-groundwater measurements and calculated groundwater elevations When measured on November 9, the depth to groundwater ranged from 68 27 to 69 59 feet flus implies that in most of the wells, the water table was at or below the base of the I" Riverbank aquifer, which is at 70 5 feet in GT-12, 68 feet in GT-13, and between 65 and 70 feet in GT-14 and GT-15 However, the 1St Riverbank aquifer is more deeply incised in the vicinity of GT-5 and GT- 6, and the lower part of this aquifer appears to be saturated in these wells (Figure 5) Elsewhere only the 2nd and 3`d Riverbank aquifers are saturated at the present time Comparison of the elevation data in the nested wells suggests that there are slight differences in the elevation of the piezometric surface between the three Riverbank aquifers In GT-14, the difference between the 2nd and 3`d aquifers is only 0 03 feet, but in GT-15 the difference is 0 12 feet (almost 1 5 inches) In GT-13, the difference is 0 2 feet, which is nearly 2 5 inches However, the depth to water in GT-13A is suspect, because it was less than 1 foot above the base of the screened interval and the fluid might be water used during drilling to prevent heaving sand rather than true groundwater As the data in Table 2 illustrate, the water table has fallen 4 feet in the past 11 months 3.4 Hydraulic Gradient and Groundwater Flow Direction Three groundwater elevation maps were constructed from the data in Table 2 Figure 10 was constructed using the data from GT-5, GT-6, GT-9, and GT-13A, all of which are screened in the 1St Riverbank aquifer The first three are screened from 50-75 feet and GT-13A is screened from 57-67 feet Figure 11 was constructed using the data from GT-1, GT-3, GT-12, GT-14A, and GT- 15A, all of which are screened in the 2nd Riverbank aquifer The screened interval in GT-1 and GT- 3 is 75-100 feet, the screened interval in GT-12 is 85-105 feet, and the screened interval in the other two is 80-90 feet Figure 12 was constructed using the data from GT-13B, GT-14B, and GT-1513, all of which are screened below 100 feet in the 3`d Riverbank aquifer The data for the 1St Riverbank aquifer suggest that the groundwater flow direction is to the north (Figure 10) The data for the 2"d Riverbank aquifer suggest a more westerly flow direction, but the elevation difference in four of the five wells is only 0 01 feet, so even a very small error in the casing survey or depth measurement could yield a different flow direction (Figure 11) The data for the 3`d Riverbank aquifer imply a southward flow direction, opposite to that for the 1St Riverbank (Figure 12) 3 4.1 Historical Groundwater Flow Directions Table 4 summarizes all the existing data on groundwater flow directions at the site Since the investigation began in 1994, 27 groundwater elevation maps have been constructed The first several maps were constructed using the three-point method and were based on three wells screened in the 2❑d Riverbank aquifer (this was not apparent at the time) Due to the alignment of the wells and the small difference in groundwater elevation in these wells, the flow direction was highly 7