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<br />-16- <br /> <br />VI7. Alluvial Valley Floors - Rules 7.06.8 and 9.29 <br />The applicant has provided a reconnaissance level alluvial valley floor study <br />in Section 2.06.8 of the permit application. There are basically two alluvial <br />systems which could be impacted by the operation. The Raton Creek system, <br />which is located along the west side of the permit boundary, will potentially <br />be impacted by the surface disturbance. A tributary drainage to the Moores <br />Canyon drainage basin will be undermined at the northeastern corner of the <br />permit area. Both systems are tributary to the Purgatoire River. <br />D.N. Emling Company, the consultant who prepared the alluvial valley floor <br />study, maintains, on the basis of field reconnaissance and air photo inter- <br />pretation, that no streamlaid alluvial deposits which are greater than 50 feet <br />wide and occupied by a stream channel exist within the permit area. This <br />applies specifically to the portion of the Moores Canyon drainage which will <br />be undermined by the operation. No alluvial deposits meeting the size <br />criteria for alluvial valley floors will be undermined by this operation <br />during the initial permit term or anticipated life of the mine. <br />Zt is not known whether significant alluvial deposits meeting the size criteria <br />for alluvial valley floors are situated along the bfoores Canyon drainage down- <br />stream of the permit boundary. The potential for any negative impacts on <br />potential alluvial valley floors downstream of the permit area is minimal for <br />the following reasons. <br />The only aspect of the operation which is most likely to impact this drainage <br />is the extension of mine workings into the drainage basin. No surface <br />disturbances are planned for the Moores Canyon drainage. Further, the mine <br />workings will only underlie 8.8 acres, or approximately 0.29, of the <br />Moores Canyon drainage basin (3070 acres). Due to the steepness of slopes <br />(33~) combined with the Iow annual precipitation of 14.32 inches which normally <br />occurs as high intensity events of low frequency, surface water runoff will <br />tend to occur as infrequent, short duration runoff events. Because of the <br />short duration of these runoff events, possible subsidence effects (short of <br />total collapse of the surface) would not be expected to significantly diminish <br />flows. For these reasons, the potential for diminution of the quantity of <br />surface water supplied to alluvial valley floors in Moores Canyon is very <br />remote. <br />As rr~ntioned in the ground water section of this Findings Document (Section XVI), <br />no mines in the area have experienced notable inflows into the workings. <br />Additionally, the only ground water sources in the area of the projected <br />mine workings in Moores Canyon are seeps and springs which originate in the <br />Raton Formation outside of the permit area which are hydrologically isolated <br />from the proposed mine workings. There is little to no potential for the <br />operation to affect these seeps and springs. Therefore, the potential for <br />diminution of the quality and quantity of ground water supplied to alluvial <br />valley floors in Moores Canyon is also remote. <br />