2004-04-28_REVISION - M1977020 - Laserfiche WebLink

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Greg Lewicki And Associates 11541 Warrington Court Parker, CO USA 80138 Steve S. Shuey DMG Grand Junction Field Office 101 South 3`d Street, Room 301 Grand Junction, CO 81501 Dear Mr. Shuey, Apri15, 2004 I have addressed the adequacy issues in the attached document. I will also address the issues in the form presented in your Second Adequacy letter dated February 20, 2004. New Area 1. Proofs of mailing for the requested parties aze included. 2. Response adequate. 3. Response adequate. 4. Response adequate. At this time, no off-site structure other than those covered by releases is neaz a slope steeper the 3H:1 V. As mining progresses into AM-3's area, some structures will fall within the 200' envelope. Because the DMG requires proof that a structure will not be damaged due to slope failure and not proof of stability, we choose to show proof that in the event of failure, the failure surface will not extend outside the permit area. The proof follows: All future steep slopes(O.SH:1 V) will be limited to a 65 foot offset from the permit boundary. This offset is derived from a 20 foot offset for the crest of the 3H:1 V slope plus a 45 Foot offset. A failure would be governed by the internal angle of friction of the material. Raveling would occur at the top of the slope unfil the internal angle of friction is met. The position of the midpoint of the slope would remain unchanged while the overall slope length increases. The limit of the failed slope is an angle of 38 degrees or ~1.3H:1 V. (A copy from a text book is included.) Therefore in the event of failure the crest of the highwall would move less than 10 feet, leaving 55 feet of buffer between the permit boundary and the highwall. It should also be noted that near vertical (O.SH:1 V) highwalls have remained on this site for an extended period of time(yeazs). This alone is Phone: (303)346-5196 Fax(303)-346-6934 E-Mail: lewicki7@at[bi.com