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CashMineNon-DMOCeltification AdrianBrown <br />3.5 Acid Rock Drainage <br />Mine backfill is currently intended to be mined material that is not ore. This material will be blasted, <br />with a grainsize considerably smaller than the in-situ rockmass. The ability of this material to form acid <br />rock drainage (ARD) has been evaluated by obtaining samples from transects across the orebody at the <br />level where the currently-planned mining will take place (Level 3). The results of the rock tests are <br />presented in Attachment 1, and summarized in Table 1. <br />Of the seven samples taken in the veins to be mined (5 samples), and of non-ore country rock to be <br />mined (2 samples), all but one is net neutralizing, The one sample which showed net acid generating <br />potential (Sample #5) is ore, which contains only 2.2% sulfide sulfur, which is a modest amount for a <br />sulfide ore vein. All the vein material that is blasted will be mined and processed, with the sulfide (and <br />gold) removed by that process. Therefore the only potential that the vein material has to adversely affect <br />any person, any property, or the environment is to the extent that the remaining face at the edge of the <br />mined area might be subject to sulfide oxidation. The remaining face is intact, and of very small surface <br />area. The average ore material is slightly net acid generating (NNP = -5 tons per 1000 tons of ore). <br />However, the country rock surrounding the ore is net neutralizing (NNP = 35 tons per 1000 tons of <br />rock). As the overburden forms the walls and some of the mine back, and all of the mine backfill, there <br />is significantly more acid neutralizing material in the mine than acid generating material. <br />This preponderance of acid neutralizing material in the mines in the district is attested to by the quality <br />of the water at mine portals. Natural oxidation occurs in all of the orebodies in the area that aze above the <br />natural water table. The products of that oxidation flow to mine portals, where water either pools or <br />seeps into the portal rockpiles. None of the water at mine portals in the district is acidic (including the <br />Cash Mine), providing demonstration that al] mines aze in a net neutralizing condition even when <br />abandoned. <br />Based on this assessment, no acid-producing materials will be disturbed in quantities sufficient to <br />adversely affect any person, any property, or the environment. <br />3.6 Toxic-Producing Materials <br />The materials produced by the proposed mining are ore, which is removed from the mine and processed <br />in the mill, and overburden, some of which is retained in the mine as backfill, and the remainder <br />processed with the ore in the mill. <br />The ability of this material to produce toxic materials within the orebody veins that are intersected by the <br />mines has been tested by total analysis of metals. The results of these tests are presented in Table 1 (test <br />results) and Table 2 (ore and country rock). Water flowing through the orebody veins in the rockmass <br />contact the products of oxidation of the orebody materials, and transport them to the mine openings. The <br />water quality in the mine openings (presented in Table 3) therefore provides a measure of the extent to <br />which oxidation of the orebodies produces toxic materials. <br />Based on the results of Table 3, only zinc and sulfate exceed the corresponding secondary drinking water <br />standard, and only zinc exceeds levels that might injure cold water fisheries (the USEPA "Gold Book" <br />table value for cold water fisheries is 47 ug/L), were the mine water ever to exit the mine and flow into <br />those waters. However, during operation no water can flow from the mines to the environment (as they <br />7601A-20067210 4 <br />