2012-09-06_REVISION - M2008070 (25)

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Design and Operations Plan Western Gravel E & P Waste Disposal Facility • Public and Environmental Isolation — WGDF is isolated from the public. The White River and facility location at the top of a terrace provides isolation from the state recreation area that is located at the opposite side of the river to the northwest. Gated facility access further isolates the property from the general public. Additional security will include fencing placed around each active landfill cell. Environmental isolation will be achieved using landfill design criteria ( Section 17) exceeding required designs for a solid waste landfill. Double lined waste cells wi 11 be constructed that include leak detection and leachate collection and removal systems. Additional isolation will be provided by the proposed SWCS. Moreover, geologic and hydrologic conditions will provide additional environmental protection. The upp er portion of the Wasatch Formation underlies the site. Documented permeabilities of 1 x 10 centimeters per second (cm/sec) to 1 x 10 -9 cm/sec and over 1,000 feet of claystone, siltstone, lesser mudstone, and shale and channel sandstone beds exist beneath the site. Surface and Groundwater — The White River floodplain borders the north and east sides of the WG property, but is located approximately 45 feet lower in elevation and approximately 205 feet from the planned facility. A shallow unconfined aquifer exists below within alluvial floodplain gravels. Groundwater may be present in the Wasatch Formation in discontinuous sandstone members at depths greater than 200 feet according to the nearest existing domestic water supply well logs. Distance to Domestic Wells — Several water supply wells permitted for domestic, commercial, gravel pit, and monitoring uses are located northwest of the landfill facility. The closest permitted domestic water supply well to the landfill facility is located approximately 9,700 feet to the northwest and owned by Bridget Rondell. 2.3 ENVIRONMENTAL SETTING 2.3.1 Archaeological Inventory Because of the extensive disturbance of the site during gravel mining operations, a cultural resource inventory was not conducted. Proposed landfill activities will be conducted in order to reclaim former mining locations. 2.3.2 Geologic Conditions 2.3.2.1 Geologic Setting The site is located at the northern portion of the Piceance Basin in the Colorado Plateau physiographic province. The terrain is characterized by high plateaus and deep valleys. The proposed landfill is located on a low terrace bench located approximately 45 feet above and to the south and west of the White River. The closest that any constructed cell will be to the river and/or associated wetland is approximately 200 feet and the closest any cell will be constructed to the edge of the terrace is 50 feet. The terrace face exposed to the river exhibits a slope ranging from approximately 45 degrees to nearly vertical. The White River flows in a general east to west direction. The Piceance Basin is an asymmetrical, northwest trending Laramide -age depositional basin that exhibits gently dipping west and southwest flanks and sharply dipping east flank. The G rand Hogback formed by the White River Uplift to the east, separates the Piceance Basin from the White River Uplift. The Douglas Creek NWCC, Inc. October 24, 2011 Page 7 of 51