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<br />The applicant has not adequately determined the probable hydrologic <br />consequences of the proposed underground mining operations upon the <br />stream/alluvial aquifer systems of the Santistevan Canyon. Until the <br />surface and ground water resources are fully inventoried and the probable <br />hydrologic consequences of mining upon these resources is assessed, <br />secondary and retreat mining beneath the alluvium of Santistevan Canyon <br />cannot be approved by the Division (See Stipulation 8 in Section VI, <br />Hydrologic Balance; Ground Water of this findings document). <br />The applicant originally provided a discussion of the water quality <br />effects of mine discharge from the Golden Eagle Mine upon the Purgatoire <br />River stream-alluvial aquifer system. These anticipated effects were <br />based on estimates of discharge which are substantially less than those <br />currently experienced. <br />The water discharged from the mine is a sodium-bicarbonate type water <br />with a pH in the range from 7.6 to 9.1. During the monitoring years 1984 <br />through 1987, the water averaged a TDS level of 834. (See Data in <br />Exhibit 10 of the permit application). Discharge from the mine during <br />early 1988, which included water from the fracture zone encountered in <br />the Second Right entries, falls within this pH range and about this TDS <br />value. Maximum flow from the mine in early 1988, however, currently <br />exceeds the earlier anticipated maximum values of approximately 180 gpm. <br />Flow from the mine may approach 500 gpm at maximum development. Mass <br />balance calculations of the effects of such flow on the Q7-10 value for <br />the Purgatoire River indicate this discharge would increase TDS values in <br />the river during such a low flow by 58 mg/1 to a total of 261 mq/1. The <br />resulting dissolved solids value for the river, however, is below <br />Drinking Water Standards of 500 mg/1 so use of the water for drinking <br />purposes will probably not be affected. Using representative values of <br />Ca, Mg, and Na concentrations for Purgatoire River water at PR-2, <br />upstream from discharge of the mine water and for the Golden Eagle Mine <br />discharge water, a resulting SAR value of 7.68 was calculated for the <br />Purgatoire River water below mine discharge point. This does not exceed <br />the normal irrigation water standard value of 12; so use of the water for <br />irrigation purposes is not precluded. <br />The applicant has received approval to construct a 6 acre coal refuse <br />pile at the mouth of Ciruela Canyon as a result of TR-04. In the process <br />of receiving this approval, the operator satisfied the requirements of <br />Stipulation No. 9. <br />After the cessation of mining operations, the Golden Eagle Mine water <br />would no longer be discharged and the workings would flood. The recovery <br />of the piezometric surface of the coal aquifer would occur in two <br />stages. The first stage would be a relatively slow increase that would <br />occur as the mine workings are filled by ground water inflows. Once the <br />underground workings have been filled, the piezometric surface would <br />rapidly rise toward its eventual steady state position. A permanent <br />depression in the piezometric surface would exist in the vicinity of the <br />flooded mine workings. The magnitude of the depression would not be <br />-20- <br />