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shows that following subsidence, a limited number of fractures were observed •~ at the surface , (approximately two inches wide and six feet deep). The ground surface subsided an average of three feet over the panel. Powderhorn Coal Company currently mines coal using room-and-pillar methods. Overburden thickness ranges from 100 to over 2,200 feet. Overburden thickness increases to the southeast. The mining plan provides for leaving protesti~+~illars~beaeath:6oFter~woode•~~apid,.,Jerry~and~C oal.G.ree}c~,s:to eli~iraa~tea~e.possibili~y~of~sub~sfd"e'nce~ A 12° angle-of-draw is used to calculate protection zones under the creeks. Refer to Tab Section 20 for detailed information regarding pillar design for subsidence control. Effects on Surtace Water in the Rapid Creek Basin Rapid Creek drains most of the area overlying the Roadside South Mine. Rapid Creek is intermittent. Cottonwood Creek is a major tributary of Rapid Creek • and Oak Springs Creek is a minor tributary. Cottonwood Creek and Oak Springs Creek are usually dry by late summer. Powderhorn Coal Company has been monitoring flow on Rapid Creek and Cottonwood Creek since the end of 1985. Four flumes have been installed, one on upper Rapid Creek, two along Cottonwood Creek, and one below the confluence of the two creeks. The second flume was added a Cottonwood Creek in 1993 as mining progressed to a point near the existing flume. Data has been submitted in Powderhorn's annual hydrologic reports. Gain-and-loss estimates of these stream discharge data have not been performed because the town of Palisade diverts and recirculates water in both creek basins. Refer to Tab Section 18 for more information on the Hydrologic Monitoring Plan. ~L1~e/~~..ti ~ ~~~ _~~ (New 3/1/96) (~,~,,,~ Q~ o- C ~S,ti ~F.~'~p,H