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Cross Mine(M1977-410) Technical Revision No. 5 <br /> Discharge from the Cross Mine reports directly to Pond#1 via pipeline(Figure 1).This water requires daily <br /> addition of lime(5—15 lbs. daily)to meet discharge standards for the NPDES permit maintained through <br /> CDPHE. From Pond #1 the water is directed via pipeline to the larger Pond#2, at a rate of approximately <br /> 2-54 gpm. Discharge from the Idaho Tunnel does not require treatment to meet the effluent standards <br /> for the NPDES permit and is sent directly to Pond#2,at a rate of approximately 30-35 gpm.The combined <br /> water in Pond #2 discharges to Coon Track Creek where it is sampled bi-monthly at the discharge point <br /> and reported to CDPHE in accordance with the NPDES permit. <br /> This TR is not proposing any changes to the current area of disturbance,operational methods,or facilities <br /> previously approved. <br /> 3. Purpose <br /> The purpose of this TR is to provide for rehabilitation of the Idaho Tunnel portal to re-establish flow of <br /> mine water that meets NPDES discharge requirements. Rehabilitation of the tunnel portal will require <br /> temporary surface waste rock storage,rail salvage and timber disposal.All aspects of the mining operation <br /> and reclamation plan will remain the same. <br /> 4. Need <br /> 4.1. Portal Rehabilitation <br /> Entrance to the Idaho Tunnel was in such a state of neglect and disrepair from long-term gradual <br /> deterioration that it was not safe to enter and operate the mine water system per the approved permit. <br /> In particular, the timber ground supports at the portal had failed to the point it was tilted dangerously <br /> askew (Photograph 1), and collapsed completely in some portions of the tunnel (Photograph 2). The <br /> ground slopes adjacent to the portal also exhibited signs of shallow slope failures and sloughing. <br /> r. e <br /> —4007 ‘1.440 <br /> 4,1 <br /> • <br /> $ h <br /> Photograph 1—Idaho Tunnel Portal prior to Rehabilitation <br /> 3 <br />