2001-04-20_REVISION - M1977342 - Laserfiche WebLink

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,' Mr. Allen C. Sorenson • • Henderson Mine, Permi[ No. M-77-3A2, Revision No. TR-8 Page 3 mg/I) detected at a value between the MDL (0.02) and the POL (0.06 mg/I). Henderson has been routinely manifesting this sludge as anon-hazardous solid waste to the BFI landfill on Highway 93 in Jefferson County. The HDS is located in drying ponds at the Woods Creek water treatment facility at Urad. The material is fine grained with the consistency and appearance of silty soil as shown in Figure 1. Optimum moisture content was tested at 34 percent with estimated strength of about 6000 psf or 41.6 psi, indicating that the sludge will easily support LGP heavy equipment if not overly wet. 2.2 Pond 1.2 Pond 1.2, originally designed as a mine water holding/sedimentation pond in the original water treatment system, is located at the Henderson Mine site approximately 500 feet south southeast of the gate and approximately 600 feet north of Hoist House #1. The pond is a 26 acre-foot, sub-grade pond that was constructed using standard construction methods with an excavator and haul trucks. The pond is generally rectangular with a footprint area of 76,480 square feet or 1.76 acres. The pond is lined with a 40-mil High-Density Polyethylene (HDPE) liner that is anchored into the pond berms. The inlet to the pond consists of a concrete flume structure with two 16 inch HDPE conveyance pipes that enter the pond. The pond outlet consists of a single 16 inch HDPE conveyance pipe that terminates into a concrete outlet box. 3.0 Sludge Deposition A number of methods can be employed to move the HDS into Pond 1.2 such as truck and wheel-loading, crane and hopper, and fixed conveyor systems. However, the least complicated and most cost-efficient means appears to be based on the use of 60 foot portable wheeled conveyors similar to those commonly used in sorting and moving aggregate and soil materials. 3.1 Preparation and Access Given the location and configuration of Pond 1.2, loading should be conducted from the east side of the pond to the west. While access and ease of operation is somewhat better from the north side of the pond, this would block the main access road to the east portion of the site. In addition, the east-west scenario is better suited to interior pond water management as discussed in Section 3.3.