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E~~A <br />~S Cca~Ccmpany ~ Seneca Coal Company <br />March 14, 2000 <br />Mr. Michael Boulay, <br />Division of Minerals and Geology <br />1313 Sherman Street, Room 215 <br />Denver, CO 80203-2273 <br />R8: Yoast Mine Permit C-94-082, Landslide Above Poad 012 <br />Dear Mr. Boulay: <br />Enclosed please find information addressing bullet point item <br />number 1 in your. March 10, 2000 letter with regard to the <br />landslide that has occurred in the vicinity of pond 012. Since I <br />will be on vacation the remainder of this week, bullet point item <br />numbers 2 and 3 are being worked on and will be submitted to the <br />Division as soon as possible. <br />As you already know the landslide was detected on the afternoon <br />of March 6th during your inspection of the Yoast Mine. The slide <br />must have occurred, during the previous weekend, .because the pond <br />• was inspected on Wednesday March lat by myself, Jay James and <br />Tom Leidich, both from Montgomery Watson. A crack ran from the <br />water level at pond 012 in the northwest aide of the pond, up <br />along the slope in a northeast direction to a section of the Haul <br />Road D berm and ditch. Two separate areas of the fill material <br />comprising the road berm slope had slumped to the south. <br />When we returned to the office that night I immediately contacted <br />both Jay and Tom to come out the following morning to investigate <br />the failure. That way we would be able to come up with some <br />recommendations to minimize any additional slope deformation. <br />We returned to the pond 012 site the following morning and met <br />with Jay and John Pellicer, also from Montgomery Watson. The <br />slope on the north side of the pond had moved substantially <br />downs lope overnight. The slide body was estimated to be about 300 <br />feet wide (along slope strike) by 100 feet long (along the slope <br />dip) in its largest dimensions. The head scarp at its maximum <br />dimension is approximately 20 feet. The slide body has not <br />impacted the pond 012 embankment and appears to terminate about <br />60 feet upstream of the embankment. The upstream portion of the <br />slide body terminates at about the upstream end of the pond. <br />It appeared that the surface water coming down the haul road <br />ditch above the slide area, which was saturated, may have <br />delivered enough water to trigger the slide. This can be backed <br />• up by the fact that this entire area was still under total snow <br />cover when the pond was inspected on the lat. There were no <br />Seneca Coal Company • P.O. Drawer D • Hayden, Colorado 81639 <br />Telephone (970) 276-3707 • FAX (970) 276-3014 <br />