2007-11-15_PERMIT FILE - M2007044

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11) Ore Pad Construction: The Applicant proposes compaction of the upper twelve inches of soil on the ore pad to decrease permeability and calls out a specification for compaction to 90 percent maximum dry density based on a standard Proctor. The Division requires compaction for soil liners to 95 percent of maximum dry density. This is not an onerous requirement as most soils suitable for use as liners reach 90 percent density in stockpile, and compacting to 95 percent will result in a significant decrease in permeability compared to 90 percent. The Division further requires that for a project the size of the ore pad, a minimum of one Proctor test on a representative sample of the soil, and a minimum of two density tests on soil following compaction. In order for soil to be effective as a liner it must behave plastically. The upper twelve inches of soil to be compacted on the ore pad must have a minimum plasticity index of 10 percent. If there are no onsite soils that meet this criterion, the Operator must use imported soil or soil amendments to increase plasticity, or PTO Limit t stsl must berconducted oDnlrepresentative sol approval. A minimum of three Atterbe g samples during construction of the ore pad. The Operator may not use the pad for ore storage until the compaction is complete and the Division has reviewed and accepted the soil test results. Also, the Operator must periodically inspect the pad for indications of desiccation and freeze/thaw effects that will increase permeability. If these effects are observmdacted.pThetOperatorcmust report onsoreepad orked, moisture conditioned as needed, and co p inspections and any reworking of the pad soil liner in each annual reclamation report. 12) Placement of the soil liner should have a temperature limitation. No frozen soil liner materials shall be used as liner fill. Preparation of the native area should be a major consideration prior to placement of the soil liner fill. It must be reasonably smooth and void of large rocks and objects. 13) Surface Water Management: The Applicant proposes a number of permanent surface water diversion structures in the mining and reclamation plans. These structures have been sized to safely pass flows from a 100-year, 24-hour precipitation event. Since the diversions are to remain following reclamation, the Division requires that they be sized to pass flows resulting from the probable maximum precipitation event. 14) As a matter of QA/QC, all construction of major features should be reviewed on site by DRMS staff prior to commencement of construction. Please commit to notifying the Division in writing at least 10 working days prior to the beginning of construction of stormwater control features, ore pads and proposed buildings. The Division may at its discretion require apre-construction inspection and on site monitoring during the actual construction. In all cases a detailed post construction report shall be required within 30 days of completion of the project or prior to commencing use which ever date is less. 15) The submitted mining plan indicates that some areas that have previously been reclaimed at the site will be redisturbed during the proposed new activity. The applicant should indicate whether