2012-09-06_REVISION - M2008070 (25)

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Design and Operations Plan Western Gravel E & P Waste Disposal Facility 2.0 FACILITY DATA 2.1 GENERAL DESIGN CONCEPTS October 24, 2011 Page 5 of 51 The facility will accept E &P solid waste generated by oil and gas industry exploration and production activities that is exempt from classification as a hazardous waste under RCRA Subtitle C. The waste will generally include drilling cuttings, and other wastes associated with exploration, development, or production of crude oil, natural gas, or geothermal energy and that are uniquely associated with and intrinsic to these types of operations and are therefore "exempt waste ". In addition, non - exempt PCS associated with E &P activities and other sources (e.g. various petroleum releases and spills) will be accepted for disposal. All waste accepted at this facility will be defined as solid waste. The engineering DOP is consistent with all applicable state regulatory criteria as stipulated in the Regulations. Site characteristics (e.g. geologic and hydrologic conditions including the Wasatch Formation with no shallow groundwater, semi -arid climate, and rural area) are favorable for development of this type of facility. In addition, the facility is located proximal to numerous E &P facilities in the Piceance Basin region that generate waste proposed for disposal at WGDF. The facility design must meet Sections 1 through 3 requirements of Regulation 6 CCR 1007 -2 (Regulations Pertaining to Solid Waste Disposal Facilities). Although not required in the Regulations, design criteria used for WGDF exceeds criteria associated with a solid waste facility. Because of the presence of the adjacent White River and the inherent nature of proposed waste, the facility has been designed in order to incorporate an added measure of protection to the environment and include a more stringent design. The facility waste cell design consists of components (e.g. clay bottom liner, double high density polyethylene (HDPE) liner system including incorporated liner leak detection and leachate collection and removal systems) not necessarily required at solid waste disposal facilities. A Surface Water Control System (SWCS) shall be included in order to mitigate potential stormwater run -on and run -off from the facility. In addition, the SWCS is designed in order to control stormwater associated with a 100 -year, 24 -hour storm event. The WGDF facility will be developed in phases beginning with Cell A. As Phase 1 mining progresses to the east and south, additional separate waste cells will be constructed and filled following mining completion. The Phase 1 deposit is to be mined to bedrock and is relatively shallow. The anticipated life of each cell is dependent upon actual depth to bedrock following mining operations and waste disposal demand. General and conceptual facility engineering designs and operations are presented below. Actual cell locations, sizes, and footprints presented in this plan are considered preliminary and may be slightly changed based upon final construction design requirements. In order to expedite facility construction, detailed construction level design criteria of initial Cell A are included in the DOP for CDPHE review and approval purposes. As cell development progresses to additional phases (e.g. future cells), construction level design drawings and details will be provided to CDPHE for review and approval prior to construction. General design criteria associated with the proposed WGDF are summarized as follows. • Five contiguous, double -lined waste cells are anticipated to cover approximately 14 acres at build out. • Estimated total capacity of 397,000 cy of waste excluding daily cover at build out. • Double lined waste cells using 40 mil and 60 mil HDPE liners. • Leak detection systems placed in interstitial space between liners. • Leachate collection and removal system located above the upper HDPE liner. • SWCS designed to mitigate potential stormwater run -on and run -off and control stormwater associated with a 100 -year, 24 -hour storm event. • Wet/dry wells located to intercept potential cell leakage migrating through bedrock. • Closure and Post - Closure Plan NWCC, Inc.