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Mr. Kent Gorham <br />October 21, 1996 <br />Page 4 <br />Imported mine inflow volumes associated with dust suppression activities are difficult to quantify. Past <br />reports appear to have focused on accounting for sources of discharge water and comparing observed <br />inflows with predicted inflow volumes. Observed inflows for 1995 reasonably approximate predicted <br />values. Mine water balance analyses have typically not been addressed in any detail. <br />4. What is the significance of points numbered 9-19 on the mine inflow map? Are points l-8, missing <br />from the map? <br />Response: Points 9-19 indicate locations where measurable inflows were documented during the <br />1995 Mine Inflow study. Points 1-8 were previously documented locations (refer to 1994 AHR Mine <br />Inflow Study Map) which were either inaccessible during the 1995 study (1-6) or which were no longer <br />producing water during the 1995 study (7-8). <br />Water Quantity and Ouality -Bedrock Wells <br />I. Field pH values are abnormally high for 91M006, 91M001, 91M004, 006-BRDH7, 9IM005, and <br />001-83-107 for the 1995 water year. Please explain these unusually high pH values. <br />Response: Field pH values for wells 91 M001 and 91 M004 were within normal ranges for the 1995 <br />water year. These sites are required to be monitored only for water levels on a quarterly basis. <br />Temperature data was erroneously presented on Tables 50 and S l and may have been confused with pH <br />data. Revised copies of these Tables are provided and should replace the copies originally submitted. <br />The elevated pH measurements recorded at well 91M006 were discussed briefly on page 3 of the AHR text. <br />Commencing in May 1995, a contractor was utilized to conduct the required monitoring at this site. Upon <br />becoming aware of the seemingly elevated pH levels at this and other sites, TCC questioned the contractor <br />regarding sampling methods being employed and instrumentation being utilized. No explanations for the <br />noted pH variations became evident. TCC continues to monitor this situation and will provide additional <br />information [o the Division if and when it becomes available. The previous maximum pH value recorded at <br />91M006 was 9.1 and occurred on June 3, 1992. A value of 9.8 was recorded in 1995. <br />The pH values recorded at 91M005, 006-BRDH7, and 001-83-107 during 1995 were within previously <br />established ranges for these sites. The maximum values of 9.4, 9.3, and 9.3 recorded for 91M005, 006- <br />BRDH7, and 001-83-107 respectively during the 1995 water year have been equaled or exceeded on <br />several past occasions at these wells. <br />3. Once again, the Division reminds TCC of the permit commitment to monitor Trout Creek <br />sandstone wells in the vicinity of the mine, should inflows into the mine occur from this unit. AHR text <br />states "Well 006-83-48C exhibited a fairly steady decline prior to being undermined during 1993...." This <br />statement would imply that mining itself does, in-fact, cause some dewatering of the Trout Creek sandstone <br />and would trigger the commitment [o monitor wells in [he region. <br />i:Wocumrnt~ihrUoidel.ckV S:dvtsp.doc <br />