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<br />M <br />6. Map 4, Hydrology, does not show the location of Ditch P'~. <br />D. Haul Roads <br />Z <br />1. The haul road cross-sections show the fill slopes as Yti':ly <br />According to Rule 4.03.1(3}(d), this slope is too steep unless <br />demonstrated that this slope 1s stable. <br />1 / ... . <br />slopes. W ~ <br />it can be j-o2'~ <br />2. In accordance with Rule 4.03.1(4)(a)(iti), the drainage ditches far the <br />haul road 1n a disturbed area and the associated sediment structures must be <br />designed for a 10-year, 24-hour storm and the design presented in the permit <br />application. <br />Backfi111ng and Grading - Rules 2.05.3(b). 2.05.4(2)(a). 2.05.4(2)(c). 4.09. <br />4.13 and 4.14 <br />A. Portal Pit Area <br />The applicant intends to backfill the abandoned Middle Creek Mine portal pit <br />according to cross sections submitted on Map No. 13. Some previous concern <br />was expressed as to whether the materials density tests were adequate.; It is <br />apparent that the tests performed which indicate a swell factor of~26%'can be <br />verified by the applicant's and the Division's experience 1n the Twenty M11e <br />Park Basin. <br />1. The Division 1s, however, concerned with the volume of material in the <br />stockpile and surrounding area that will be used as the spoils backfill. The <br />applicant states that approximately 1,128,000 bank cubic yards will be needed <br />to backfill the portal pit. According to the application 986,000 cubic vards <br />are available from the temporary overburden stockpiles leaving a deficit of <br />142,000 cubic yards. The applicant intends to scrape overburden material <br />surrounding the pit area to make up for the deficit 142,000 BCY. However, <br />there are no calculations to verify how much material is stockpiled and no <br />explanation as to why there 1s a deficit of material considering the swell <br />factor. Calculations verifying the amount of stockpiled materials are <br />needed. Regarding the deficit material further discussion is necessary. Mhy <br />is there a deficit and how was the figure determined? Mill there be cuts 1n <br />the surrounding area to obtain the material and if so how many acres will be <br />affected? <br />~ ~ti' <br />L <br />2. There is no mention of grading technique with regard to compaction effort <br />or lift height. This concern is primarily to address the problem of / <br />saturation due to ground water inflow. Minimizing permeability and porosity ./ <br />will substantially decrease the volume of water saturating the backfilled ~3 ~ pZ N,~ <br />pit. Please provide a discussion,LOf the method of compaction and grading ~{I <br />techniques. ~UmD aJ~- P~ 1 ~~~n.gr..,.i vo~l ~y <br />3. The map reference on Map No. 13, Cross-Sections is incorrect. The note at <br />the bottom should read Map No. lT - Pre-mining Topography. h I~ <br /> <br />