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2F. Refuse Pile Hauhroads <br />A new haulroad (formally classified as an access road) for construction and utilization of the coal refuse pile was <br />established parallel to the eastern margin of the pile (see Map 24). The Refuse Pile Haulroad extends from eastern edge <br />of the Refuse Pile (Coal Waste Disposal Site) to the Reject Belt and Stockpile southeast of the main Run -of -Mine Coal <br />Stockpile. The road was constructed in accordance with the dimensional specifications detailed on Figure 22, Access <br />Road Typical Sections, and surfaced with gravel or other suitable material. Northwest Colorado Consultants evaluated <br />the existing road and recommended that 13 inches of pit run gravels and 5 inches of Class VI base course be used to <br />upgrade the road to a haulroad. The road surface is approximately 20 feet wide, with an overall gradient o <br />approximately 6.5 percent. The centerline profile for the Refuse Pile Haulroad and typical haulroad cross-sections <br />are shown on Map 30, Road Profiles and Cross -Sections. <br />Access to the refuse pile was routed around completed portions of permanent diversion ditch RDA -2. Ditch crossings <br />may be required, as refuse pile construction proceeds, for the temporary diversion ditch established upgradient from the <br />working area of the pile. Crossing sites will be suitably protected with durable material to prevent excessive erosion or <br />an appropriately sized culvert will be installed. Calvert sizing documentation will be provided to the Division prior to <br />installation, if this option is utilized. <br />Topsoil salvaged from construction of the original access road is stored in topsoil stockpile SF -12, located adjacent to <br />the construction site. Road reconstruction proceeded in stages from north to south in approximately 500' segments in <br />order to maintain reasonable access to the active area of the refuse pile. In order to facilitate vehicle movement through <br />the refuse pile, a short haulroad segment was constructed off of the eastern nose of the refuse pile. The design and <br />certification of this road segment is presented in Exhibit 25F. Culvert sizing and designs for the Refuse Pile Haulroad <br />was previously approved in MR96-140. <br />2G. Batch Weigh/I,oadout Haub-oad <br />The Batch Weigh Loadout Haulroad is required for access to the Batch Weigh/Loadout facility to facilitate clean- <br />up and removal of spilled coal and general maintenance of the area. The road ties -in to existing Haulroad C, <br />crosses Foidel Creek, and runs along the toe of Pond C to the Batch Weigh/Loadout facility. The road was <br />originally approved through TR97-30 on November 24, 1997. MRO1-175 modified the original approval to reflect <br />relocation of the road to shorten the road and reduce potential wetland impacts. A subsequent Technical Revision <br />(TR02-41) further modified the design to reflect the use of smaller equipment to access the site. The revised design <br />reflects the use of 10 -ton dump trucks as opposed to the 100 -ton trucks considered in the original design. The <br />revised design is presented in Exhibit 48-2. The road has a 30 -foot top width and is approximately 550 feet in <br />length. Prior to entering the Batch Weigh Loadout, a 40 -foot length of road with a 30 -foot top width and 20 -foot <br />radius is provided to allow trucks and equipment to turn around. The haulroad has been designed in accordance <br />with Section 4.03.1(3) to support a fully -loaded haul truck. <br />The original design has been retained in the permit in the event that larger trucks are required in the future requiring <br />that the road be upgraded to the previously approved design. The revised design calls for a top width of 24 feet, <br />which is 6 feet less than the original design, however, the construction process was essentially the same as <br />previously approved under TR97-30, as modified by MR01-175. Design calculations for the depth of fill required <br />to distribute loading on the road are based on an estimate of soil shear strength of 5.21 psi in the low areas adjacent <br />to the creek and 10.4 psi in the other areas. Discussions with an engineer with experience constructing roads in this <br />area indicate that typical shear strengths for this type of soil range from 13 psi to 20 psi, so the values used for <br />design calculations are very conservative. Northwest Colorado Consultants developed a computer model of the <br />road sections and determined factors of safety for deep failure of the subgrade materials in the range of 2.0 and for <br />shallow failures in the range of 1.7, with 1:1 sideslopes on the embankments. Based on this design information, a <br />design incorporating geo-fabric and geo-grid materials to distribute loads over the soft soil base was developed. <br />Tensar design and stability analysis are provided in Exhibit 48. SEDCAD+ modeling runs were completed for the <br />10 -year, 24-hour storm over the contributing drainage basin. The model assumes that the peak flow from Pond A <br />will be occurring concurrent with the 10 -year, 24-hour event over the basin. A peak flow of 41.86 cfs was <br />determined at the crossing and a minimum pipe diameter of 30 inches was determined to be adequate to handle the <br />peak flow. Data was reviewed for USGS stream gauging station 09243800 (station 800), located approximately <br />TR12-80 2.05-71 11/07/12 <br />