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Geosyntec'� consultants Table 2: Hydraulic Conductivity Ranges at RRI Soil Type Laboratory Kv(cm/sec)' Field Kh(cm/sec)' Sand(silty to well-sorted) 2.0 x 10-1 to 5.8 x 10-6 Silt(clayey to sandy) 2.8 x 10-8 to 5.1 x 10-4 1.3 x 10-1 to 2.8 x 10-' Clay(silty to sandy) 4.5 x 10-8 to 6.3 x 10-4 Notes: ' Kv is typically at least 10 times less than Kh. 2 From slug tests in various wells and pumping tests at Sites 3,4,and IAS-11. cm/sec = centimeters per second Groundwater in the water bearing zone in the top 70 to 80 feet bgs at RRI appears to be under unconfined conditions. The drawdown responses observed during the pumping tests conducted by the Navy have estimated storage values and response curves indicative of unconfined conditions (Appendix Q. Additionally, a review of the geologic boring logs compared to the first depth to groundwater measurements in the monitoring wells indicates that the logged depth of the first wet soil is generally similar to the first depth to groundwater measurement taken in the monitoring wells.This provides another line of evidence that the groundwater at RRI is under unconfined conditions. 2.3.5 Groundwater 2.3.5.1 Depth The groundwater elevations at RRI generally range from about 1 to 12 feet below msl (0 to 15 feet bgs) and fluctuate by about 2 to 5 feet between the dry and wet seasons (Appendix B). 2.3.5.2 Flow The primary factors that control the groundwater flow system at RRI are recharge to groundwater from the rivers and channels that surround RRI and discharge of shallow groundwater into the island's internal drainage channel system (Figure 6). The hydraulic influence of the surrounding surface water bodies, combined with the discharge to the surface drainage channel system, produces a general flow pattern toward the interior of the island (Tetra Tech, 2002). The levees around the perimeter of RRI maintain surface water elevations higher than the RRI topography. Along the perimeter of RRI, groundwater flows from the higher elevation surface water bodies (1 to 10 feet above RRI Groundwater Monitoring Work Plan 12 1 June 2018