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<br />likely to be naturally occurring mineralization within the surrounding area rather than <br />ongoing site activity. In no case was the loading or dilution of in stream contaminants <br />significant. Upstream (HE-1) and downstream (HE-3} monitoring data is attached with <br />monthly average and standard deviations calculated for the eight year period 1985 <br />through 1992 inclusive. The Division also questioned the transmissivity/permeability of <br />the Precambrian bedrock. Attached are calculated values of the hydraulic conductivity <br />of Precambrian Silver Plume Granite determined from packer tests in drill holes located <br />in the URAD Valley, less than one mile away from the Mine site. <br />As a result of the discussions noted above, Division staff recommended and <br />Henderson Mine personnel agreed that a shallow well just east of the easterrn end of <br />the mine yard to characterize the groundwater flowing through the glacial material atop <br />bedrock was appropriate. <br />Responding to our concerns on timing, the Division acknowledged that <br />characterization of 'ambient' groundwater quality could not be accomplished by <br />September 1, 1993 since no prior definition had occurred. The Division sue~gested a <br />timeframe of developing the initial monitoring well during the fourth quarter of 1993, <br />sampling that well quarterly for five periods, and then based on those results submit <br />the necessary information as noted by 6.2.(3)(f) & (g) of the Act in a reasonable <br />timeframe thereafter. <br />Our tentative schedule to address the concerns noted above is as follows: <br />4th Quarter 1993 Complete monitoring we11 in location noted by preliminary <br />plan. Commence quarterly sampling for five consecutive <br />quarters. <br />1st Quarter 1995 Complete ambient monitoring program. <br />3rd Quarter 1995 With Division staff, determine the need for continued <br />groundwater monitoring. If necessary, submit the complete <br />application for Technical Revision to implement the <br />provisions of 6.2.(3)(c) of the Act. <br />This schedule is coincident with the schedule developed for the Henderson Mill <br />site and any Technical Revision required would address groundwater monitoring at <br />both facilities. <br />It was our understanding that, based on the information presented, tihe Division <br />felt that the preliminary plan and additional information requested would proroide <br />adequate data to evaluate our 3rd quarter 1995 Technical Revision (if necesssary). If <br />this is the case, by this letter we formally 'volunteer' for the groundwater monitoring <br />requirements as provided by 6.2.(3)(e) of the Act. If there is a misunderstainding of <br />the proceedings of our meeting as noted by this document, please advise us so that <br />any discrepancies can be clarified. <br />