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McClane Creek Temporary Diversion <br />During the midterm review the McClane Canyon Mine permit conducted in 1996, <br />it was determined that McClane Creek had been diverted. The road and mine facilities <br />were constructed under the authority of a USGS Exploration Permit prior to the <br />enactment of SMCRA. Review of photography from 1977 shows a newly constructed <br />road along side of a well vegetated channel. The diversion apparently occurred prior to <br />mine site construction. None the less, the operator committed to submit designs for the <br />channel; as well as, to reclaim the original channel after mining. Since the diversion of <br />the channel occurred over 20 years ago, and no designs for the channel are known to <br />exist, the channel was surveyed to determine the profile and channel geometry. <br />The survey revealed that the diversion is approximately 550 long with an overall <br />slope of 5.9%. The slope of the channel varies from nearly flat to about 25%. The <br />steeper segments are where large boulders or rocky stretches make up the channel <br />bottom. A profile of the channel, plan view of the location and calculations of peak flow <br />velocities are shown on the following pages. <br />• In 1997, the operator installed 4 wooden gabions along the channel segment to <br />stabilize the channel bottom during high flow events. A channel profile and narrative <br />description and gabion installation details were incorporated into the permit in 1998 <br />(permit appendix pages M-5 through M-9). <br />In 2004 a re-survey was conducted and the data and inspection observations <br />show there have been significant erosion subsequent to the 1997 gabion installation. <br />Future high flow events may result in additional channel scour and side-cutting erosion. <br />Portions of the diverted channel appeared to be unstable and further erosion may be <br />likely. The most effective long term solution to the erosion problem was determined to <br />be restoring McClane Creek to it's original flow configuration. Therefore, the operator <br />installed a 48" culvert, "P", at the haul road in order to reconnect upper McClane Creek <br />to it's original lower segment. Design of culvert "P" is shown in Table 4.2-13 and <br />location of the culvert is shown on Figure 2.2-3. <br />When the mine site is reclaimed, the diversion ditch will be reclaimed concurrently. The <br />area will be revegetated with the greasewood shrubland seed mix. <br />Mc Vol III Page M-5 9-28-05 <br />