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Geochemistry Review 2 25 March 2011 <br />May Day Conversion CN-1 File No. M-1981-185 <br />B. For ground water, the Division does not believe that the Idaho seep is satisfactory as a <br />ground water point of compliance due to the probability that all ground water in the May Day <br />area may not report to the Idaho Seep. The receptor of greatest concern to which ground water <br />from the site may report is the La Plata River, which is a local drinking water source. <br />Therefore, the relevant ground water contaminant limits shall be the domestic water supply and <br />drinking water standards, except as noted in Colorado Water Quality Control Commission <br />(WQCC) Region 9 stream classifications. <br />C. The Division will require at least two ground water monitoring wells between the lower <br />most mine portals of the May Day and Idaho areas and the La Plata River. Since the Applicant <br />is planning on drilling additional exploratory boreholes, the Applicant may convert, depending <br />on location and in consultation with the Division, some of the boreholes to 2-inch monitoring <br />wells and 1-inch piezometers. The parameters for ground water sampling should conform to <br />Tables 1, 2, 3, and 4 of WQCC Regulation 41. <br />7) Exhibit E - Reclamation Plan; Rule 3.1.5(2), item 2, page 6. The reclamation plan proposes to <br />permanently dispose mill tailings and debris from the dismantled mill facility in the under- <br />ground workings. The application does not demonstrate such plan will be compliant with the <br />ground water quality regulations. The Division cannot approve the proposed reclamation plan <br />until the Applicant demonstrates such plan will be compliant with the ground water regulations <br />and protective of existing and reasonably potential future uses of ground water, per Rule 3.1.7. <br />8) Exhibit E - Reclamation Plan; Rule 3.1.7(7)(a), Ground water monitoring, page 11. The <br />locations at which downgradient impacts may reasonably be expected are not well known, <br />because the ground water flow regime is not well characterized. The Applicant must submit a <br />proposed monitoring well and piezometer network that will allow the determination of the <br />ground water flow regime, including the depth to the water table at various locations in the <br />mine vicinity, the piezometric surface, ground water flow directions, and ground water <br />discharge rates. <br />9) Exhibit E - Reclamation Plan; Rule 3.1.7(7)(b)(viii), Ground water monitoring, page 12. For <br />the baseline characterization and determination of ambient ground water quality, the Division <br />requires that the ground water monitoring plan include seepage in the underground workings, <br />wherever such seepage is available for sampling. <br />10) Exhibit G - Water Information; Rule 6.4.7(2), Table on page 2. Although it has no bearing on <br />the decision rendered by the Division on this application, be advised that the information for <br />the Permian Cutler formation does not correspond to that given in Topper et al., 2003. <br />11) Exhibit G - Water Information; Rule 6.4.7(2), page 2. The application calls out Figure G-1. <br />The Division is unable to find Figure G-1. Please provide the figure or indicate where in the <br />application the information can be found. <br />12) Exhibit G - Water Information; Rule 6.4.7(3), Projected Water Requirements, page 2. Please <br />describe the ultimate fate of the 10 gpm makeup water that will be used in milling. Will it be <br />incorporated into and disposed with tailings?