Laserfiche WebLink
III IIIIIIIIIIIIIIII <br />999 <br />~ STA~OF COLORADO <br />MINED LAND RECLAMATION DIVISION <br />Department of Natural Resources <br />1313 Sherman St., Room 215 <br />Denver. CO 80203 <br />303 8663567 <br />RA x: 303 832-8106 <br />August 18, 1992 <br />Mr. Andre J. Douchane <br />Battle Mountain Gold Co. <br />5670 Greenwood Plaza Blvd. <br />Englewood. Co 80111 <br />of ~D~ <br />~~- 4t <br />Nri ~$ <br />~~r89696 <br />Roy Romer, <br />Governor <br />Michael B. Long, <br />DrviSion Director <br />RE: San Luis (Permit M-88-112) BMR Proposed Modification to Existing Ground <br />Water Monitoring System <br />Dear Mr. Douchane: <br />The Division is in receipt of the above referenced report prepared for <br />Battle Mountain Resources by John C. Halepaska & Associates, Inc. In the <br />report, it is concluded that the existing monitoring well network is adequate <br />to provide monitoring for the tailings facility and collection pond. Certain <br />assumptions were made that led to that conclusion which need to be justified <br />and are indicated below. <br />An effective porosity value of 25% was estimated for the Santa Fe <br />Formation but the source of this was not provided. Neutron logs were run <br />for the wells drilled during this project but the well logs are not <br />scaled in porosity units. No core data eras referenced. <br />Since a lower effective Dorosity value would mean a nigher seepage <br />velocity and affect the shape of any contaminant plume, the value used <br />need to be justified, i.e. well log charts provided, core data noted <br />whatever. <br />2. Lateral dispersivity and transverse disper;ivity values of 100 and 30 <br />were employed in the determination of the width of the contaminant <br />plume. lower values could reasonably be employed which would also affect <br />the shape or the contaminant Dlume, i.e. narrow it. <br />The lateral and transverse dispersivity values employed need to be <br />justified. <br />3. Using the factors available from the repo t, the Division cannot ccnfirm <br />the estimates made in the report of the ?xt?nt of the dispersion of any <br />contaminant leaking from the collection pond and tailings facility. The <br />Division believes there is potential for evidence of a leak, eg. from the <br />collection pond, to bypass Well M-9. <br />The operator shculd supply calculations and plots of contaminant plumes <br />that support their apparent conclusion `hat detectable and timely <br />evidence of these plumes would be obsarved in the existing monitoring <br />wells. <br />