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Application for Technical Revision to MLRB Permit 80-47 Page 5 of 7 a number of locations on the property. It re-enters the ground water system below the Mahogany, which retazds water flow but is not a flow barrier. In the mine, water can be observed migrating downward through the Mahogany zone via natural fractures. Hydraulic fractures created as part of ExxonNlobil's testing might provide additional downward pathways from the Upper to Lower Aquifer, but these will be insignificant compazed to the already existing network of natural fractures. Please note that the coarse ore conveyor tunnel, built in the 1980s, connects the Upper Aquifer through the Mahogany Zone with the Lower Aquifer. The mine entries and mine bench at the Colony Shale Oil Project were selected for this experimental work because the area provides easy access to oil shale. This easy access facilitates monitoring experimental results and also environmental monitoring to prevent any potential impacts. Operational Considerations The Electrofrac experiments planned for the Colony site are a relatively small-scale operation. The operational considerations associated with the experiments are enumerated below. Land Disturbance: No land disturbances outside the already established mine bench are anticipated. Activity will be focused around the two entrances to the commercial mine and will be confined to a relatively small portion of the mine bench. All the equipment and facilities to be used in this area will be temporary and will be removed at the close of the experimental work. The additional water well will be drilled from the existing mine bench. Drilling: The drilling operations associated with these tests are routine for the mining industry. A trnck/skid mounted drilling unit will be set up inside the mine to drill the lateral hole to be fractured. It is expected that the same unit will be used to drill the connector and monitoring holes from inside the mine or on the mine bench. Water for drilling operations will be extracted from surface water on the property utilizing ExxonMobil's existing water rights. The drilling unit will be electrically or pneumatically powered using a power source outside the mine. Water Discharges: The primary water usages associated with these tests will be for drilling and fracturing operations. As described above, this water will come from surface water on the property. Its anticipated that no additives to the water will be required that would prevent it being returned to the surface water system as part of the mine outflow. If it should become necessary to use additives that prevent returning the water to the surface water system, that water will be retained in temporary tanks on the mine bench. Retained water will be evaporated or disposed of off-site. No discharges of water beyond the existing surface water and storm runoff are anticipated. Solid materials recovered from water used in drilling will be disposed of safely, in accordance with any applicable regulations.