2004-07-23_REVISION - M1979205 - Laserfiche WebLink

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Plan Site Description Ezhibit D The site lies on the north and south bank of the Colorado River immediately east of the town of Rifle and just north of I-70. The portion of the site which lies to the north has been operating as a DMG 112 permited operation since 1979 with some areas of mining occuring prior to 1977(pre-law disturbances). The northern portion of the site (Chambers Pit) has been nearly mined out. However, it will continue to be used as a processing and stockpiling area for the Scott property expansion across the river. A major feature of the expansion area is lazge oxbow left from the river. The oxbow azea is a wetland and will be avoided. The site's current land exists as riparian, wetland, and imgated field. A house and outbuildings also are on the property. These may be moved prior to mining in Mining Area 3. To the west of the property lies a narrow strip of land owned by CDOT. The CDOT site is too small to be developed. To the east of the property lies the LaFarge Mamm Creek gravel operation. Site Geology The site contains Pleistocene age gravels with a bedrock of Wasatch Formation shale and sandstone. The oxbow was once an active channel of the river, but due to deposition has been naturally cut off from the current river channel. The gravel depth is expected to be 25 feet. The gravel has very little fines and is very permeable. In the irrigated fields up to 5 feet of overburden is expected. The topsoil in this area is also thicker than the riparian areas. The topsoil is expected to be 3 inches to over 1 foot in thickness. The area inside the oxbow is expected to have very little overburden and slightly less topsoil. Average topsoil and overburden depths can be seen in the Mining Area Volumes table. The water table level is expected to be around 5300'-5311' in elevation. Pre-Mining Work Pre-mining activities for the Scott Expansion will consist of infrastructure installation, sediment pond construction, topsoil and overburden stripping, and isolation berm construction. The berm will be 2 feet tall with 2H:1 V slopes and will be constructed with overburden or topsoil. These activities will take place in and around Mining Area 1-Phase 1 prior to mining. Futwe mining areas will be prepared in a similaz fashion, One truck traffic bridge and a conveyor bridge will be installed as part of the site. The bridge will be used for truck traffic across wetland areas. It will be semi-portable and built from rail flatcars. For the span two cars will be bolted together to provide sufficent bridge deck width. Drawings provided by a railcar bridge company aze included in Appedix B. Precast concrete blocks (~3'x3'x5') will be used for footings. The conveyor will be used to transfer gravel from the south side of the river to the existing facilites at the Chambers Pit. The conveyor river crossing will be designed by a licensed civil or structural engineer. The design will require that the conveyor be completely enclosed. A drawing from the supplier is included in Appendix B. 722/04 Page I~1