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<br />-48- <br />No information has been provided to indicate the presence or absence of <br />subirrigation in Apache Canyon. The information on alluvial ground water <br />included in the permit application i,~s,~ limited to the Picketwire and Stonewall <br />Valleys (exhibit 6). Because of a'~1'~`~k of site-specific information on <br />subirrigation in Apache Canyon, the DiviS:ion must assume that subirrigation <br />does occur in the canyon, unless the peioittee demonstrates the absence of <br />subirrigation in the canyon. <br />Based on the information provided, Apache Canyon is determined to be an <br />alluvial valley floor based upon the capability for subirrigation. <br />Apache Canyon Findings <br />1. The proposed operation would not interrupt, discontinue or preclude <br />farming on the alluvial valley floor. <br />The applicant has proposed no surface disturbance in the canyon. Two air <br />shafts are located upstream of the mapped alluvial deposits in the Left Fork <br />of Apache Canyon. Portions of the canyon are planned to be undermined. The <br />applicant has not projected the effects of subsidence on the alluvial valley <br />floor, so the Division can presently make the above finding only if no <br />secondary or retreat mining occurs under the canyon. <br />2. The proposed operation would not cause material damage to the quantity <br />and quality of ground water that supplies the alluvial valley floor. <br />With the exception of light use roads in Apache Canyon and two mine <br />ventilation facilities in the Left Fork of Apache Canyon, no surface <br />disturbance is planned to occur. The two ventilation facilities are upstream <br />of the area mapped as containing unconsolidated streamlaid deposits exceeding <br />50 feet in width and 10 acres in extent. The effects of the fan facilities <br />and the associated road on water quality are predicted to be minimal. <br />Portions of the canyon are planned to be undermined. The applicant has not <br />projected the effects of subsidence due to undermining the alluvial valley <br />floor, so the Division can presently make the above finding only if no <br />secondary or retreat mining occurs under the canyon. <br />3. The proposed mining operation would preserve the essential hydrologic <br />functions of the alluvial valley floor. <br />The Division has conservatively assumed that Apache Canyon is a subirrigated <br />alluvial valley floor significant to agriculture. Therefore, the essential <br />hydrologic functions must be preserved throughout the mining operation. The <br />essential hydrologic functions are those geologic, hydrologic, and topographic , <br />characteristics which make the ground water usefully available for <br />subirrigated agriculture. <br />With the exception of apre-existing light-use road to the ventilation <br />facilities in the Left Fork of Apache Canyon no disturbance will occur on the <br />alluvial valley floor. However, the applicant has not projected the effects <br />of subsidence due to undermining the alluvial valley floor, so the Division <br />can presently make the above finding only if no secondary or retreat mining <br />occurs under these canyons. <br />