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Subsidence Field Observations <br />West Elk Mine <br />August 27.29, 2002 <br />Location 7: Bcdnxk cspusurc hx;atcd at the top ul' the headwall of Boy Canyon was <br />documented to show conditions prior to mining (Figure 10). <br />Figure 10. Northwarl view through the trees, showing unstable <br />slopes in the upper part of tho MosaveMe Formation on the west <br />part o1 West Flatiron prior to mining. <br />4.2.2 Traverse H-H' <br />Phis tntvcru lxgins at the tittk in the drill road to West hlatimn and ends at Drill I lute 96-27-I. <br />• Trtverse crosses western parLe of mined-out longwall P;mcls 14 and I5. The overhurdcn <br />depth to the B-ticam ranges from I,SUU to I,GSU fl. <br />• I'nversc is in clay, soil, and colluvium primarily derived liom the overhing Ohio Croek <br />~7cmher ul'thc Mcsttverdc Forntation and the claw of the ~1'acatch Formation. <br />l.oc;ttion 8: <br />'~umeraus subsidence cracks are prcxnt near Drill I tole Df I-I5-09, <br />• Overburden depth to the R-~~am is aMiut I.j>U H. ('racks arc loca0.d in a sandstone Icdgc of <br />the Hatnn Mcrnher of the Mcs;tverde Fornlation (Figure I I ),;tnd also in clay, colluvium, and <br />uiil above the sandstone (Figure 12). <br />831-032.570 Wnght Water Engineers, Inc. Page 15 <br />December 2002 <br />