1993-09-01_REVISION - M1977493 (3)

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the seepwater collection system below #4 dam. Although it was concluded that there are no groundwater impacts to the Eagle basin due to the cutoff wall, CLIMAX suggests that a characterization well be installed between Robinson Lake and #4 dam because of future plans for the Number 4 dam site. ARKANSAS RIVER DRAINAGE CLIMAX personnel reviewed the geology and overburden thickness in the Upper Arkansas drainage down to the property line, at which point the river flows on exposed bedrock for over two miles. Division staff felt there was no need for groundwater monitoring in the Arkansas basin based on current activity but suggested that if CLIMAX contemplates future activities in the basin then baseline monitoring would be appropriate. CLIMAX agreed that indeed the establishment of baseline is appropriate and proposed an alluvial gravel monitoring well located near the property boundary. Division staff agreed with this plan. Additionally the Division asked CLIMAX to provide a geologic map of the CLIMAX Mine area, identifying those faults with potential ties to groundwater and their significance. A geologic map which includes fault traces is attached as well as qualitative estimates of their significance. Quantitative data does not exist. Responding to our concerns on timing, the Division acknowledged that characterization of 'ambient'groundwater quality could not be accomplished by September 1, 1993 since no prior definition had occurred in the Arkansas or Eagle River drainages. The Division suggested a timeframe of developing initial monitoring wells during the fourth quarter of 1993, sampling those wells quarterly for five periods, and then based on those results submit the necessary information as noted by 6.2.(3)(f) & (g) of the act in a reasonable timeframe thereafter. Our tentative schedule to address the concerns noted above is as follows: 4th Quarter 1993 Complete monitoring wells in general location noted by preliminary plan. Commence quarterly sampling for five consecutive quarters. 1st Quarter 1995 Complete ambient monitoring program. 3rd Quarter 1995: With Division staff, determine the need for continued groundwater monitoring. If necessary, submit the complete application for Technical Revision to implement the provisions of 6.2.(3)(c) of the Act. It was our understanding that, based on the information presented, the Division felt that the preliminary plan and additional information requested would provide the Division with adequate data to evaluate our 3rd quarter 1995 Technical Revision (if necessary). If this is the case, by this letter we formally 'volunteer' for the groundwater monitoring requirements as provided by 6.2.(3)(e) of the Act. If there is a