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-32- <br />permit area does not contribute measurably to stream base flow in the summer <br />months. Therefore, any impacts from subsidence cracks or spring depletion <br />would be minimal while the damage was repaired. In the event a water user is <br />impacted sufficient CWI owned water rights exist to mitigate water users, or <br />the hydrologic balance. Any impacts can be mitigated should they occur. A <br />monitoring program has been designed to monitor surface water, selected water <br />users, ponds, springs, and insignificant colluvial/alluvial areas. <br />In order to distinguish between natural and mine related water loss accurate <br />rainfall data and evaporation rates are needed. The following stipulation is <br />imposed: <br />Stipulation No. 5 <br />CWI SHALL CONTINUE TO MAINTAIN RAINGAGE AND EVAPORATION PAN MONITORING AT OR <br />NEAR THE CWI WELL FIELD. THE RAINGAGE SHALL RECORD DAILY AND THE EVAPORATION <br />MONITOR SHALL RECORD EVAPORATION MONTHLY WHEN NOT FROZEN. <br />The mine fire of June 1986 necessitated a change in the sequencing of the mine <br />plan. Asa result both Steven's Gulch and East Roatcap Creek will be <br />undermined within the current 5 year mine plan. When CWI mines under Steven's <br />and East Roatcap Creek water may be encountered even if there is no <br />subsidence. Faults and fractures may be encountered underground that are in <br />communication with the stream and its associated alluvial/colluvial deposits. <br />Dewatering of these faults and fractures could deplete streamflow and the <br />alluvium/colluvium when water is present. Water has been encountered in other <br />underground mines where mining has occurred beneath ephemeral, intermittent or <br />perennial streams. Hawk's Nest Mine, Somerset Mine, Mid-Continent, Blue <br />Ribbon Mine and North Thompson Creek Mine have all had inflows as the result <br />of undermining streams. However, in this case the streams do not contain <br />aquatic life nor are they supplying agricultural areas. The limited <br />depletions are not predicted to be significant enough to cause a major change <br />in stream characteristics or impact the hydrologic balance. The only concern <br />with depleting Steven's Gulch or East Roatcap Creek stream flow would be to <br />water users within those drainages. CWI has responded to this concern in <br />their water replacement plan. The Division's findings on this issue are <br />included in the Water Rights and Replacement discussion in Section VII of this <br />document. <br />Based on data from other mines in the valley the Division would anticipate <br />stream related inflows to be only a few hundred gallons per minute at worst <br />case during certain times of the year when the streams are flowing. The' <br />operator through a detailed investigation and analysis, has predicted that <br />worst case inflows would only amount to 8.7 gpm by 1989, and would increase to <br />33.5 gpm for the life of mine. A mitigation plan was presented by CWI that <br />will replace the water depleted by mining. <br />The hydrologic consequences of the mine are expected to be minimal. The <br />applicant reports that no degradation of water quality in surface streams is <br />expected. Arly effluent will be treated as necessary to meet quality standards <br />prior to discharge. Although mine inflows are currently small+ if significant <br />inflows are encountered the application contains a plan for a 4ollection and <br />treatment prior to discharge. <br />Y`t <br />