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`~ <br />'~ Mr. Allen C. Sorenson <br />Henderson Mine, Permit No. M-77-342, Revision No. TR-8 Page 2 <br />HENDERSON MINE <br />Deposition of High Density Water Treatment Sludge in Pond 1.2 <br />1.0 Introduction <br />In 1996, Henderson constructed a water treatment facility at the site of the <br />historic Urad Mine in the Woods Creek Valley to collect, consolidate, and <br />treat water from both the active underground mine and the defunct Urad <br />Mine. Henderson determined that an alkaline precipitation system producing <br />High Density Sludge (HDS; 25% solids or greater) would meet the revised <br />effluent limitations of their CPDES discharge permit. This treatment facility <br />was commissioned in 1997, and has been successfully treating this mine <br />water since start-up. <br />A Technical Revision (TR-8) was submitted to the Colorado Division of <br />Minerals and Geology (DMG) in June 1999 seeking approval from the DMG <br />to dispose of the dewatered HDS produced in the water treatment process in <br />Pond 1.2 at the Henderson Mine site. Pond 1.2 initially was approved, <br />constructed, and utilized as a sedimentation holding pond in the Henderson <br />Mine water treatment system prior to construction and commission of the <br />present Urad facility. In this capacity, Pond 1.2 originally contained alkaline <br />treatment sludges. While the TR was favorably received by DMG, <br />clarification was required as to how the sludge would be loaded into the lined <br />pond without breaching the integrity of the liner system. <br />Using information supplied to Henderson by W.W. Wheeler and Associates, <br />on-site investigation of Pond 1.2, and knowledge of the Henderson Mine <br />systems, a practical and cost-efficient scenario for delivering the HDS to the <br />pond is presented herein. <br />2.0 HDS and Pond 1.2 <br />While it is not the intention of this report to reiterate TR-8, the following <br />information is presented for purposed of integration with the TR. <br />2.1 Sludge Characterization <br />HDS from the Henderson water treatment facility is very stable, alkaline, non- <br />hazardous and non-toxic. It is composed of precipitated metals and gypsum, <br />contains no sulfides, and is highly inert. Analytical results (Appendix D) from <br />TCLP (EPA Method M1311) testing show a pH of 9.8 and only barium (0.02 <br />