2012-09-06_REVISION - M2008070 (25)

Home Browse Search

Design and Operations Plan Western Gravel E & P Waste Disposal Facility October 24, 2011 Page 8 of 51 Arch forms the northwest basin boundary that separates the Piceance Basin from the Uinta Basin located to the west. The Fort Union, Wasatch, and Green River Formations are Paleocene and Eocene age lacustrine rocks that were deposited in ancestral Lake Uinta, located in northwest Colorado and northeast Utah. These three formations are present in the Piceance Basin. Based upon published information, the facility is located in the vicinity of the Wasatch Formation and overlying Green River Formation contact. The Fort Union Formation underlies the Wasatch. Bedrock at the site has been identified as Wasatch Formation. Wasatch in the area has been characterized as claystone, siltstone, mudstone and shale of mostly fluvial origin up to 4,000 feet in thickness. Underlying Fort Union, Wasatch, and Green River Formations in the Piceance Basin are late Cretaceous age rocks belonging to the Williams Fork Formation. Economically significant deposits include the Garden Gulch and Parachute Creek Members of the Green River Formation that overly the Wasatch contain significant oil shale deposits. Both Garden Gulch and Parachute Creek Members are located in mountainous terrain to the southwest. Garden Gulch Member is located approximately 1/2 mile and Parachute Creek Member approximately one mile from the site. Geologic information is provided in Appendix B. 2.3.2.2 Unconsolidated Materials Unconsolidated materials at the site consist of alluvial clay overlying terrace sands and gravels that are located on bedrock benches above the White River. Alluvial deposits associated with the river are mainly silty sand and rounded gravel and cobbles composed of sandstone, quartzite, basalt, and granite fragm ents. Gravel deposits at the site are currently being mined and processed (e.g. crushed, screened) for commercial use. Maximum thickness of the Quaternary age gravel and clay deposits at the site is approximately 15 feet to 20 feet. Based upon United States Department of Agriculture (USDA) published data, shallow soil at the site is classified Borollic Calciorthids -Guben complex that is found on terraces and 6 to 50 percent slope s. This complex extends east and west along a terrace that overlooks the White River to the north. This well drained complex typically ranges to depths up to 60 inches below ground surface (bgs). Both the Borollic Calciorthids portion of the complex and Guben portion are characterized as various type loams. However, Borollic Calciorthids is composed of finer materials (e g Channery loam, clay loam, loam, silt clay loam) than the Guben (e.g. extremely to very gravelly sandy clay loam, very gravelly clay loam, extremely gravelly sandy loam, very cobbly sandy loam). The capacity of the most limiting soil layer to transmit water is moderately high in the Borollic Calciorthids and moderately high to high in the Guben. Flooding and/or ponding do not occur in this complex. Shallow soil to the south is classified as Yamac loam that occurs on 2 to 15 percent slopes. Yamac consists of fine loams (e.g. loam, clay loam, silt loam) and extends to depths of approximately 60 inches bgs. Yamac is well drained and the capacity of the most limiting layer to transmit water is moderately high to moderate. Flooding and/or ponding do not occur in Yamac loams. Tremble loam is located in lowlands along the White River and north side of the property but outside the COD. Moderately well drained Tremble consists of loam and sandy loams that occur along stream terraces, flood plains, and valley floors that exhibit zero to three percent slope. Tremble soils can extend to depths of approximately 60 inches bgs. Capacity of the most limiting layer to transmit water is high. Unconsolidated materials information is provided in Appendix B. NWCC, Inc.