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<br />-34- <br />• as previously mentioned, Salt Creek !fin.inq Companu has proposed a 25,000 cubic <br />yard underground development ~easte disposal site to be located adjacent to the <br />Munger Canyon .'tine. This waste rock pile will cover 2.6 acres and will be 35 <br />feet ti.gh (see Section 2.1.5 of volume I of the application). Roof fall rock <br />from both the Munger Canyon and McClane Canyon .Nines, along with rack slope waste <br />rock from Munger Canyon will be disposed of in this waste rock pile. The pile <br />will be Located outside of the ephemeral tributary to ;4unger Creek and surface <br />drainage from undisturbed areas will be diverted around the pile. Surface <br />runoff from the disturbed area will be collected in a sediment pond for treatment. <br />No springs discharge in the area to be covered by the waste rock pile. an <br />alluvial monitoring well, GW-6, is to be installed below the waste rock pile to <br />monitor the effect of the structure on alluvial ground water (see Hydrologic <br />Balance: Cround Water section of the permit document). <br />The analyses of the Cameo roof and floor strata contained in Tables 2.1-4 and <br />2.1-5, volume I of the McClane Canyon permit application indicate that the <br />strata associated with the Cameo seam have high sodium adsorpticn ratios (SaR) <br />and high pH's. These conditions indicate that the material may limit revegetati ve <br />success on the reclaimed waste rock pile unless the pile is adequately covered <br />with non-toxic soil and rock materials, analyses of the material to be generated <br />by the rock slope, as required in Stipulation ~vo. 1, will indicate whether or <br />not material in the waste pile will be toxic. If these analyses indicate the <br />material is toxic, mitigation will be required, as specified in Rule 4.14.3. <br />Salt Creek Mining Company has demonstrated that the waste disposal pile will <br />be located outside of the 100-year .`food plain of .Munger Creek. The reach of <br />• the Munger Creek stream channel Zn the vicinity of the proposed waste pile will <br />totally contain the 100-year flood (based on an analysis of measured channel <br />cross-sections). <br />The reclamation plan (Pfap 3.1-11 indicates that Salt Creek tdini.ng Company intends <br />to reestablish the drainage at .the mine bench to approximate the pre-mining <br />configuration. an analysis of the expected velocity of flow in the drainage <br />indicated that velocities for the reestablished drainage are potentially very <br />erodible for the I00-year, 24-hour storm event (approximately 26.5 feet/second <br />+'n steeper reaches of the channel). The post-mining topography does not differ <br />markedly From the pre-mining topography. <br />:n the pre-mining ccnfiguration, the steepest portions of the stream channel are <br />composed of a resistant rock ledge, which explains the stability of the natural <br />stream. channel. When the area is reclaimed, unconsolidated material will be <br />backfilled over t!:e original channel. The unconsolidated material would obviously <br />be Zess resistant to erosion than *_he resistant rock ledge. <br />Seca vse of the high erosional velocities anticipated for the pest-mining configur- <br />at_'on, it would be advantageous to construct a permanent structure in t.`:e reach <br />of the stream chat would experience the greatest erosion. Sor this reason, the <br />following stipulation is reovired by the Division: <br />u <br />