2007-12-11_GENERAL DOCUMENTS - M1982112

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7. Geology A. General Geology of site -The sand to be mined in this operation was deposited primarily by a blend of alluvial (water-borne) processes and aeolian (wind-borne) processes. It appears that the sand deposits here were laid down well within the last million years as streams flowed from the Palmer Divide to the north into the Colorado Piedmont and thence on to the Mississippi River and the Gulf of Mexico. Because most of the sand appears to have an alluvial source, deposits tend to exhibit a high degree ofnon-uniform distribution. This was caused by meandering of the ancient streams that deposited the material. Mining of this sand sometimes involves simply excavating a large area where sand was deposited, but other times it amounts to "chasing" a seam of sand across an area. Sometimes, individual pockets of sand are separated by areas where there is no sand of any significance. Exploration of this deposit at this location showed a fairly high consistency in the deposit over the entire area, but a few areas did show locations where sand was weak and finer particle sizes more prominent. Because this operation produces both high quality sand for specialized uses as well as a material often called construction fill, the variations found in the deposit are well within the expected range of variation. Based on the exploratory pits, made with a backhoe and immediately filled back in, nearly all of the site contains sand of suitable quality. However, the actual depth of the sand is probably greater than the mining operation can mine. There appears to be deeper material present, but it is generally below the water table. Because complex water right and water use issues develop when groundwater is exposed, no mining will extend below the level of the water table and generally it will only go as deep as the point where moist, soft sand is encountered. That invariably indicates the water table is only a few feet deeper than the current surface. Staying on firm ground when conducting the operation is important because if the water table is approached closely the sand sometimes exhibits quicksand-like characteristics which causes equipment to become stuck. When that occurs, the lost time and the cost of extracting the equipment can cause the cost of mining to exceed the value of the product. When that is added to the complications of exposing the groundwater, it is rarely worth the effort to mine that deeply when the product is only sand. This is further discussed in Appendix B which is the mining plan from the Reclamation Permit amendment. Miller Gravel Pit -Special Use Permit Page 9 of 26