ENFORCE26844 - Laserfiche WebLink

Home Browse Search

~'- Engineers Planners ~ Economists Scientists February 26, 1990 DEN 18343.A0 Cyprus Orchard Valley Mine P.O. Box 1299 Paonia, CO 81428 Attention: Mr. Robert T. Johnson Senior Mine Engineer Subject: West Portal Cut Inspection Gentlemen: At your request, our Mr. Micha] Bukovansky visited the Orchard Valley Mine on February 9, 1990. The purpose of this visit was to inspect the site of the 1989 west portal cut failure, which at that time was repaired by excavating a major part of the failure, general flattening of the slope, and by a partial removal and relocation of the topsoil stored at the top of the slope. We requested during our site visit that four sections across the slope be surveyed so that the final cut configuration can be compared to the cut configuration recommended in our previous studies (CH2M HILL Letter to Cyprus Orchard Valley Coal Corporation, dated May 24, 1989). Four Sections, A-A', B-B', C-C', and D-D' were surveyed by Cyprus following our visit. These Sections coincide closely with the Sections surveyed previously; they were surveyed in straight lines rather than in segments. The comparison of the recommended and actual Sections indicate that, except for Section A, the slope in the topsoil stockpile was excavated at a slightly --~ steeper slope (about 2.2[H]:1[V]) than the recommended slope (2.5[H]:1[V]). The cut slope below the topsoil stockpile was excavated at slightly steeper slope _.~ (about 1.6[H]:1[V]) than recommended (2[H]:1[V]). The reason for the steeper slope below the topsoil storage (area of the landslide, between both benches) is apparently a slightly excessive width of the upper bench. The width of this ~--~ bench was supposed to be 10 feet; it appears that it is wider, up to 15 feet. In summary, the final cut slopes appear to be slightly steeper than those recommended earlier. CH2M HILL 6060 S. lNillow Drive. Greenwood Village. Colorado 80111-5112 303.771.0900 Marling dtldress: P.O. Box 225D8. Denver, Colorado &0222