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Mr. Rick Mills -5- 2.05.6 Mitigation of Impacts of Mining Operations Please provide a statement as required by Rule 2,05 regard to the cliffs to be undermined and subsided disturbance activities (roads or structures). September 15, 1993 .6(2) (a)(iii)(C) with or affected by surface The Probable Hydrologic Consequences section needs to be updated for the Foidel Creek Mine. Data in the permit currently used to make predictions is outdated and new predictions are required based on data collected to-date. All numbers representing increased or decreases in quality or quantity should be supported with calculations. Baseline data and other data used in the calculations should be referenced by its source (AHR, year, USGS data, etc.). Those changes attributable to Foidel Creek, Eckman Park, and Mine 3 should be separated and identified due to the overlapping nature of the respective permit areas. Previously approved values or limits are not if interest at this time. Analysis during low flow period is of particular concern. The low flow period is defined as July-September of each year. Noted deficiencies currently are: a. Site 800 is not indicative of baseline quality on Foidel Creek. Site 14 is baseline for Foidel Creek. (Table lOD). b. Baseline alluvial water quality is not represented by any wells at the Foidel/Middle Creek confluence due to upstream mining impacts. Please submit baseline water quality data for the alluvial aquifers upstream of any mining on Middle and Foidel Creeks. c. Wadge baseline water quality is not represented by TDS concentrations of up to 2042 mg/1. Previous estimates approximate Wadge TDS at approximately 1000 mg/1. Please provide Wadge quality data for the Eastern Mining District from samples obtained from the exploration drilling program. d. Table 3 uses Fish Creek average flow and mine discharge average flow. Low flow average for Fish Creek and mine discharge maximums should be used. TDS concentrations for mine discharge used currently are too low. Recent data shows TDS concentrations at site 115 at 5000 mg/1 at Site 115. (h1. Middleton, phone conv „ 9/3/93). Table 65 is outdated and is not current concerning information related to the Eastern Mining District. Either update this table or delete it from the permit. The Division also requires that all responses to the 1992 Foidel Creek Annual Hydrology Report Review and the 1992 Mine 1', Mine 2 and Eckman Park Annual Hydrology Report Review be resolved prior to PR-03 approval. No complete evaluation can be made at the present time concerning the proposed Eastern Mining District Hydrologic monitoring plan due to outstanding concerns or insufficient information. However, some concerns identified to date are: