2012-09-06_REVISION - M2008070 (25)

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Design and Operations Plan Western Gravel E & P Waste Disposal Facility parameters for sample analyses will be prescribed based upon requirements of the proposed treatment facility. Leachate monitoring, removal, and disposal documentation shall be maintained in the Operating Record. 3.4.7 Waste Cell Construction October 24, 2011 Page 27 of 51 The approximately 2 to 4 acre waste cells will be constructed as needed, depending on demand. Each cell will be a stand alone area and consist of a separate double liner system, LDS, and LCRS. Cell construction will begin with Cell A and future cells will be generally constructed to the east and south as mining progresses. A one foot thick protective soil layer will be placed over the liner system and LCRS as quickly as practical so that exposure of the LCRS to precipitation is minimized The LCRS gravels and protective soil layer must be placed in a manner that equipment used to spread and compact these materials will not damage the underlying LCRS, LDS, or liners. The 12 -inch layer of LCRS gravel placed over the primary liner and 16- ounce geotextile must be placed in one lift using a lightweight track loader or dozer with a maximum earth contact pressure specification of 8 psi. A Cat D5, smaller dozer, or a rubber tracked skidsteer will meet the maximum contact pressure specification. The one foot thick protective soil layer placed over the LCRS gravels and layer of 6 -ounce geotextile must be placed in one lift using a light to medium weight tracked dozer or loader with a maximum earth contract pressure specification of 16 psi. A Cat D8 or smaller dozer will meet the maximum contact pressure specification. Compaction of the protective soil cover will be minimal to prevent damage to the LCRS and underlying liner materials; however, enough compaction must be obtained to allow vehicular traffic into the cell and maintain the soils on side slopes. A ramp will be constructed down into the cell as the protective soil layer is placed in order to provide access to other cell areas and to provide access for trucks hauling waste into the cell. The ramp will be constructed by placing and compacting on -site soils along one of the longer side slopes of the cell. The ramp should be a minimum of 20 feet in width and have a maximum grade of 12 %. Haul trucks will dump waste in the base area of the cell and waste will subsequently be spread using a tracked dozer and/or loader. Waste materials will be track compacted using the dozer after leveling each load. The initial waste lift should range from approximately 2 feet to 4 feet thick and be spread across the floor of the cell in order to provide additional protection to the LCRS and reduce the area subjected to precipitation. 3.4.8 Daily and Interim Cover Placement /Air Emissions A minimum 6 -inch thick daily soil cover or alternative cover (e.g. Posi- She11TM) shall be placed over waste at the end of each day that waste is received and disposed. Placing cover will help prevent leachate generation and suppress volatile organic compound (VOC) air emissions. In accordance with fed eral and CDPHE, Air Pollution Control Division (APCD) regulations, VOCs may not be disposed of using evaporation. Therefore, the intent of placing daily cover is to prevent VOC air emissions. It should be noted that using daily cover is in accordance with APCD approved VOC air emission control engineering practices. Based upon waste characterization analytical results, if waste proposed for disposal does not contain petroleum constituents (e.g. VOCs) and since the proposed waste stream are soils, daily c over may not be required if allowed by CDPHE, Air Pollution Control Division. An air emissions permit specific to petroleum contaminated soils (PCS) will be obtained from APCD. As landfilling progresses, certain areas of a cell may be left in- active until area fill begins or pending cell closure cover placement. Placement of interim cover will minimize erosion and leachate generation. Areas in- active for 30 days must be covered with a minimum one -foot thick interim soil cover. Soil used for daily and interim cover shall be obtained from the areas discussed in Section 3.3. NWCC, Inc.