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Section 13
<br />Geochemical Data and Analysis
<br />¦ St. Jude Mine Development Rock: arsenic, fluoride, molybdenum, nitrate, pH,
<br />selenium, sulfate, uranium, and vanadium.
<br />¦ West Sunday Mine Development Rock: arsenic, cadmium, chloride, molybdenum,
<br />nitrate, nitrite, pH, selenium, sulfate, uranium, and vanadium.
<br />¦ Composite Ore Stockpiles: antimony, arsenic, copper, lead, molybdenum, nitrate,
<br />selenium, sulfate, uranium, and vanadium.
<br />¦ Sunday Mine Low Grade Ore: antimony, arsenic, molybdenum, selenium, sulfate,
<br />and vanadium.
<br />Overall, ore sample leachate metals concentrations are greater than the development
<br />rock leachate metals concentrations, which is expected given that the ore has
<br />increased ore mineral content. It should be noted that groundwater in the vicinity of
<br />the Sunday Mines Group is not classified with respect to designated uses (CDPHE
<br />Regulation 42); and therefore, the human health, drinking water and agricultural
<br />criteria are not formal standards for groundwater at the Sunday Mines Group. In
<br />addition, current groundwater uses in the vicinity of Sunday Mines Group do not
<br />include Human Health, Drinking Water and Agricultural uses (CDM 2009c).
<br />Additional information regarding current and future uses of groundwater in the area
<br />is included in Hydrogeologic Evaluation of t1w Sunday Mines Group, San Miguel, Colorado
<br />(CDM 2009b), which is included in this document as Attachment O and also in
<br />Section 8.3 - Existing and Future Groundwater Uses.
<br />The MWMP test is a screening tool, and other factors must be considered to fully
<br />evaluate the potential for development rock to produce leachate. These additional
<br />evaluations are presented in the following paragraphs. Although groundwater
<br />standards are used to assist in the screening process, there are no regulatory
<br />standards that apply to MWMP test results.
<br />To further evaluate if the development rock should be considered as a toxic-forming
<br />material, this section evaluates the potential for the rock piles to generate leachate in
<br />significant volumes. This is a factor of the climate of the area and the physical
<br />characteristics of the piles. Two methods were used in this analysis:
<br />¦ A water balance approach; and
<br />¦ Unsaturated flow modeling.
<br />Water Balance Estimation of Percolation: This calculation estimates percolation through
<br />the Sunday Mine Group development rock areas using a water balance approach
<br />(adapted from Guymon 1994). To clarify water balance terms, percolation is the
<br />volume of water that discharges from the base of the rock pile measured as cubic
<br />inches percolation per square inches of rock pile footprint (i.e., inches). Infiltration is
<br />the volume of water that infiltrates the surface of the rock pile measured as cubic
<br />inches percolation per square inches of rock pile footprint (i.e., inches). Water that
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<br />7164986-Denison Mines\Task Order 4 - EPP Sunday Mines GroupTINAL EPPTINAL - Environmental Protection Plan Sunday Mines.doc
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