2015-08-03_REVISION - P2009025 (4)

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It might also be considered that radon (a radioactive gas produced in the radioactive decay chain of ura- nium) may be released from the orebody, and might ultimately affect conditions at the surface. However, the life of radon is short (it has a half life of 3.82 days), and it decays to below normal background levels in the time it takes to pass through less than 10 feet of rock or soil material. Accordingly, it is not possi- ble for radon emanating from the orebody to affect conditions on the surface. Note, however, that radon occurs naturally in many rocks, and it is always prudent to check any residential space for radon. Groundwater Use Groundwater in the area has been evaluated in great detail, in particular as a part of the engineering and environmental studies performed during the permitting period for the proposed mining activity. The loca- tions of known wells (some of which may still exist) are shown on the accompanying map. These studies show that potable groundwater is available to all tracts with relatively shallow wells. Groundwater in the area exists in four different geological materials, most of which are present on each of the tracts on the South T -Bar Ranch. The details of the groundwater availability are as follows: • Alluvium. There is up to 40 feet of alluvium in Tallahassee Creek and its tributaries. Groundwater is freely available to most wells in this material, and is of very good quality, with total dissolved solids content being less than 400 milligrams per liter. This groundwater is not impacted by the orebody, and it meets all primary drinking water standards. • Shallow Bedrock. The upper 600 feet of bedrock at the Ranch contains groundwater that can be extracted at limited rates (up to 50 gallons per minute per well). The water has not been affected by the uranium orebodies, but is of lower quality than the alluvial water due to the long residence time in the rock. Typically this water contains about 600 milligrams per liter total dissolved solids, and it meets all primary drinking water standards. • Deep Bedrock. The deep bedrock in the area is of Precambrian Age, the oldest know rocks on earth. These rocks yield water with difficulty, and the quality of the water is generally fair. Typical total dissolved solids content is about 1,400 milligrams per liter, and it is very hard. Generally this water has not been affected by the orebodies in the area, and while it is not a particularly good source of drinking water due to the dissolved constituents, it meets primary drinking water standards (but not secondary standards). • Orebody. The orebody rocks occur at depths greater than 600 feet, in locations that are identified on the attached maps. The orebody rocks contain groundwater of very poor quality, with total dissolved solids contents in excess of 6,000 milligrams per liter, and relatively high dissolved metal concentration (although the uranium concentration is low). This water does not meet drink- ing water standards. The water is brackish, and is therefore easy to identify by taste. Accordingly, potable groundwater is readily available in all locations on the Ranch, but it would be pru- dent to limit new water wells to less than 400 feet to avoid the possibility of encountering brackish, metal -bearing orebody water. It is not possible to inadvertently consume orebody water, due to its taste. Summary In summary, the uranium orebodies that underlie part of the South T -Bar Ranch area have no impact on surface activities, and do not affect the availability or quality of groundwater at the Ranch provided wells are not drilled to great depth.