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1~~1~ Memo RECEIVED T« Jim Stover MAR 0 5 2004 From: Collor Stewart and t,xeg Hunt Date: 315!04 lion of Mu:erals 8 Geology Re: Rock Fall Design Parameter Selection In thrs memorandum I w01 attempt to address two issues of wncem relative to the ongang review of our applicatlon before the Dnnsion of Minerals and Geology for fhe constructbn of rock tall banns at the Bowie Resources, LLC, Mine No. 2. These issues are: 1. Smell area of influence potentially impacted t>y minfng subsidence 2. Desrgn parameter of a Sfl rock cube for the proposed rock fall bens. Issue 1. SrmaM Area of Influence of Minmo Subsrdence ,,,~ f~ There is a small area of Uu3 channel sandstone outcrop that is potentially Impacted by mining subsidence from the WD1 longwall panel. The malonty of the channel sandstone outcrop Iles ouLslde ~,~. the zone of potential Impacts of mining subsidence based on the 25 r~ - ova~r.u // ~~ degree angle of draw. It should be noted that in the spepfic geometry at the comer of a bngwall panel, especially for the fist P,a`0 + U ~ panel in a new mining dlstrfct..t rs common for the angle of draw to ~. ~,+~ ~,a be Tess than that observed at other palls along the edges of the ~, - ,~ Ruv.w longwall panel. 6~ W 9erm• ti ~~ Issue 2. Rock Srze Des'sm Parameter for Rode Fall Berm BOwiO Resources, LLC has Conducted numerous excavations with in the slump area tluhng the past Mro years. These excavations have varied in s¢o and have inducted: • Access roads to dnl pads • Doll pads • The B-58am pedal area box cut The determination of the Sft cube size for the rock tall design basis was based on obsenatpns dunng these excavations as well as observations froth abng the outcrop and areas tlown slope horn the channel sand outcrop. Canstrucbon o- access roads and dritl pads indkated a maximum bock size dimensbn of loss than 3 feet. '