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<br />-3- <br />The good news is that with seepage of 39,375 cu. ft. of water over the life of <br />the mine, I have calculated that pond water will penetrate less th n two feet <br />into the under-lying alluvium. This calculation is based on the p rosity, <br />hydraulic conductivity, initial water content, and the water Conte t required <br />to produce flow, of the alluvium under-lying the pond. It would r uire total <br />seepage of 880,000 cu. ft. of pond water to produce a flow that would <br />penetrate the alluvium to the contact with the Santa Fe Formation, nd even <br />then the slug of pond water would have to induce a flow in the Sant Fe and <br />penetrate the additional 100 feet to the water table before any imp cts to <br />ground water would occur. <br />My conclusion from all this is that although the composite liner de ign is not <br />nearly as conservative as the SRK technical memorandum would have y u believe, <br />it is still adequate to prevent pond water from impacting the grown water. <br />Ground water impacts could only occur if large amounts of water wer escaping <br />the pond through the liner due to blunders in the implementation of the <br />design. Although it is unlikely that pond seepage will reach the w ter table <br />over the life of the pond, it is obviously desirable that pond Ovate be as <br />benign as possible because there will be some seepage from the pond that will <br />impact interstitial water in the unsaturated zone. As a further caveat, I <br />would point out that although this is a state of the art composite liner with <br />a high level of QA-QC applied during installation, that an integral feature of <br />any containment facility is down gradient ground water monitoring. Long-term <br />ground water monitoring is the only way to assure that containment ~s <br />functioning as designed. <br />ACS/eke <br />cc: Jim Pendleton <br />Jim Stevens <br />Larry Oehler <br />Harry Posey <br />Mike Long <br />3766E <br />