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McClane Canyon Mines, along with rock slope waste rock from Munger <br />Canyon will be disposed of in this waste rock pile. <br />The amended original permit application contained several deficiencies <br />with regard to the underground development waste pile, which have been <br />remedied in supplemental submittals. The applicant has prepared and <br />submitted an acceptable geotechnical and stability analysis of the <br />proposed 25,000-cubic-yard underground development waste pile. This <br />analysis determined that the pile will achieve a minimum static slope <br />safety factor of 1.684, based upon conservative assumptions of the <br />waste material's strength. The applicant is also committed to an <br />inspection and certification program which conforms with the <br />requirements of Rule 4.09.1(11). The applicant's plan for the disposal <br />of underground development waste of the Munger Canyon Mine is in <br />compliance with the requirements of Rules 2.05.3(6) and 4.09. <br />Surface runoff from the disturbed area will be collected in a sediment <br />pond for treatment. No springs discharge in the area to be covered by <br />the waste rock pile. An alluvial monitoring well, GW-6, has been <br />installed below the waste rock pile to monitor the effect of the <br />structure on alluvial ground water (see Hydrologic Balance: Ground <br />Water section of the permit application). <br />The analyses of the Cameo roof and floor strata contained in Tables <br />2.1-4 and 2.1-5, Volume I of the McClane Canyon permit application <br />indicate that the strata associated with the Cameo seam have high <br />sodium adsorption ratios (SAR) and high pH's. These conditions <br />indicate that the material may limit revegetative success on the <br />reclaimed waste rock pile unless the pile is adequately covered with <br />non-toxic soil and rock materials. Analyses of the material to be <br />generated by the rock slope, as required in original Stipulation No. 1, <br />will indicate whether or not material in the waste pile will be toxic. <br />If these analyses indicate the material is toxic, mitigation will be <br />required, as specified in Rule 4.14.3. <br />Salt Creek Mining Company has demonstrated that the waste rock disposal <br />pile will be located outside of the 100-year flood plain of Munger <br />Creek. The reach of the Munger Creek stream channel in the vicinity of <br />the proposed waste pile will totally contain the 100-year flood (based <br />on an analysis of measured channel cross sections). <br />The reclamation plan (Map 3.1-1) indicates that Salt Creek Mining <br />Company intends to reestablish the drainage at the mine bench to <br />approximate the pre-mining configuration. An analysis of the expected <br />velocity of flow in the drainage indicated that velocities for the <br />reestablished drainage are potentially very erodible for the 100-year, <br />24-hour storm event The post-mining topography does not differ <br />markedly from the pre-mining topography. <br />In the pre-mining configuration, the steepest portions of the stream <br />channel are composed of a resistant rock ledge, which explains the <br />stability of the natural stream channel. When the area is reclaimed, <br />unconsolidated material will be backfilled over the original channel. <br />The unconsolidated material would obviously be less resistant to <br />erosion than the resistant rock ledge. <br />-37- <br />