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STATE OF COLORADO <br />DiV(SION OF MINERALS AND GEOLOGY <br />Depanmenl of Nalurai Resources <br />I J 13 Sherman $1., Room 215 <br />Oenver, Cobrado 80203 <br />Phone: 1703)066-7567 <br />FA%: (303183&8166 <br />DATE: March 18, 1994 RnY Romer <br />Governor <br />TO: Oarp Curtiaa Ken Sala:,~ <br />E.ecvrM nva~or <br />PROM: Allen Soreaeon Midud 6.:or~K <br />UVnron ~VC(fb <br />RE: Oeotecbnical Eoglaeerinq Report, Holaaa, Iac., slab Caayoa Quarry, File <br />Mo. M-7T-347 <br />The concluelon ie drawn in the ceotechnicel Hngineering Report submitted in support of <br />the Slgb Canyon Quarry amendment application, that the proposed load-out benches wLll <br />be stable. This conclusion is contingent upon compliance wlth the earthwork <br />recommendations included in the report. In accordance with those cecoaunendat lone, the <br />applicant should specifically commit to: <br />1. Place and compact load-out bench fill in horizontal lifts not to exceed 2 feet <br />Ln loose thickness. <br />2. Complete density teat ing of soffit Tent frequency to demonstrate that load-out <br />bench fill ie compacted to minimum BS percent of Standard Proctar~Deneity. <br />3. complete gradation tearing and material claeeification in Buff ic•lent frequency <br />to demonstrate that load-out bench fill does not vary appreciably from the <br />samples tested Lor material strength properties. <br />4. Hxerc ire Buff icient control over placement of loadrout bench fill to assure that <br />the fill dose not contain organic, plaet is (clays, topsoil, etc.), frozen, oc <br />other deleterious materials. <br />5. Provide adequate drainage to direct surface water around the out=slope of the <br />toad-out benches. <br />I have not provided a required Frequency for density or gradation tenting, oc materials <br />claeeification, because thane need to be Bite specific determinations. For example, <br />if the operator can show that a epecif is compaction methodology (e.g. x number of <br />passes with a loaded haul truck, or track walking with a certain size dozer) results <br />in the required minimum density, and if the fill le consistent in material propert iee, <br />the frequency of denelty teating could be low. If the P111 ie not consistent, a much <br />higher frequency of testing and claeeification would be indicated. <br />The operator should provide ae-built drawings and narrative, in terms of the foregoing <br />list of items, in the annual reports for the Slab Canyon Quarry. These annual report <br />inclusions would be required during each year that load-out benches are constructed. <br />C:\WP51\SI.AH.GCS <br />