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<br /> <br />Inflow from the haulage tunnel at the 7500 level 200- <br />300 gpm <br />(sec. 2.2) - Estimate add'1. 500 gpm inflow caused by <br />future development below 7500 level <br />Section 2.3 Mine Closure <br />"Although Mine closure under this alternate scenario (or any <br />scenario) required by the DMG in this TR will not eliminate <br />the need for pumping-treatment-discharge of Mine waters, it <br />will minimize and delay the process." <br />The degree to which the alternate plan will minimize and <br />delay water treatment needs to be closely examined, and <br />needs to be subject to conservative assumptions. <br />"...the collection and pumping station at the 8100' level <br />would flood within 4 to 8 years". Discharge from the 8948' <br />west portal would occur between 9 and 17.5 years. <br />Section 2.3.1 - Tunnel Sealing <br />Design Pressure of 350 psi (flooding to glory hole elevation) <br />22 ft. bulkhead length yields 1.25 FS <br />earthquake loading FS? <br />CMC specifies type V cement and 2500 psi compressive strength <br />but gives no concrete mix or testing schedule <br />The American Concrete Institute (ACI) specifies sulfate <br />resistant cement, type V, for "moderate sulfate ion <br />concentration. The haulage tunnel bulkhead should be designed <br />in accordance with the ACI code requirements for concrete in <br />contact with "very severe" sulfate ion concentrations, which <br />specify a water-cement ratio of 0.45 by weight and fly ash <br />pozzolan. <br />CMC specifies a 6" SS pipe, but gives no weight, no thrust <br />collar design. <br />Low pressure grouting of the concrete-rock contact will be <br />req'd, otherwise and unmanageably long bulkhead would need to <br />be installed. <br />Section 2.3.2 Pumping and Water Discharge <br />"Once the bulkhead was installed, the 200-300 gpm of water <br />entering the mine through the tunnel would be halted". <br />This implies that all of the 200-300 gpm entering the <br />mine from the haulage tunnel is derived from a source <br />that is west of the proposed plugging location. Where <br />and what is the source of the 200-300 gpm? Once the plug <br />is installed, ground water inflows to the haulage tunnel <br />west of the plug will be forced to discharge from the <br />west portal. How will these flows be handled? <br />"As discussed in Section 2.3, it will take a minimum of 9 <br />years for waters to reach the tunnel portal at 8948' without <br />