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At the end of this letter, we ask that a meeting be held soon after your receipt of this letter in <br />order to resolve all issues and to avoid delay in final acceptance of all elements of the technical <br />Revision. <br />1. Effect of Freezing and Thawing on the Permeability of Soil Liner Fill. <br />This issue was raised in the OMLR's memorandum of February 2, 1996 and more information <br />was requested. CC&V responded to the OMLR's request providing an analytical assessment of <br />the driving factors that would create a situation that could lead to cycles of freezing and thawing <br />increasing the permeability of [he soil liner fill beneath the synthetic geomembrane. The <br />OMLR, in its letter dated March 25, 1996, cited a study of freezing and thawing effects on <br />permeability written by Zimmie, T.F., and La Plante (1990), reporting that the freeze-thaw cycle <br />would increase the permeability of the soil cited in the study. The OMLR appears now to <br />conclude that adequate water is already contained in the Soil Liner Fill to supply water to create <br />the increased permeability. <br />The OMLR further concluded that CC&V's demonstration that additional water will not be <br />available during freeze and thaw cycles is not completely acceptable because the overlaying <br />synthetic liner will have imperfections that will allow it to leak prior to loading of ore. <br />In CC&V's March 4, 1996 submission to the OMLR, CC&V states that a water source must <br />exist in order for the frost expansion to occur in the Soil Liner Fill. The underdrain system was <br />re-described. That system extends to any springs or seeps that are observed. In this manner, <br />water is unable to infiltrate the Soil Liner Fill from the underlaying granodiorite bedrock. <br />CC&V believes that the OMLR's conclusion regarding the availability of water overlooks the <br />freeze-thaw-soil expansion process. The work of Quinn et al that was cited in CC&V's March <br />4, 1996 letter identifies additional water as one of the critical factors in the freeze-thaw process. <br />It is CC&V's conclusion that there is inadequate water contained within the Soil Liner Fill, as <br />placed, to provide the "fuel" to enlarge pores which might ultimately coalesce into continuous <br />cracks that could adversely affect permeability. <br />The OMLR assumes that there would be a source of excess water into the upper surface of the <br />Soil Liner Fill at locations of imperfections and notes that these locations are the very places <br />where the low permeability Soil Liner Fill is needed. CC&V would like to point out the <br />probability or frequency of liner imperfections is low and this probability is further reduced by <br />the subtraction of ore-loaded segments from the area of possible liner imperfections because <br />loaded areas, as is recognized in the referenced OMLR letter, would not remain in an area <br />experiencing cyclical freezing and thawing. <br />As is likely clear to the OMLR, the first lifts of crushed ore are loaded from the bottom of the <br />lined areas out onto the higher areas. This loading sequence is appropriate to maintain stability <br />on the synthetic liner in sloping areas. Therefore, those areas that are not yet loaded with ore <br />will, of course, not be receiving leach fluid. The only source of moisture would then be <br />2 <br />