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Jeff Gregg Co—)January 5,2006 <br /> Page 5 <br /> CIVIL RES,URCES.ILC <br /> STABILITYANALYSES RESULTS <br /> Setbacks listed in Table 1 indicate the minimal setback from the structure to the mining limbs. The setback distance can <br /> be increased as needed to address other restrictions. <br /> TABLE 1-SLOPE STABILITY RESULTS AND SETBACKS <br /> Section Location Critical Structure Modeled Surcharge,psi Mining Setback,ft Factor of Safety <br /> AA' North Phase 1 WCR 23.75 250 50 from Property 1.25 <br /> BB' South Phase 1 Concrete Ditch 250 50 from Ditch 1.096 <br /> CC' West Phasel Storage Building 1500 32 from Property 1.030 <br /> DD' West Phase 2 Storage Building 1500 50 from Affected 1.056 <br /> Land Boundary <br /> EE' West Phase 2 Utilities/WCR 23.5 250 30 from Property 1.009 <br /> FF' South Phase 2 Gas Well/Pipe 250 12 from Property 1.052 <br /> GG' North Phase 3 Residence 250 50 from Property 2.11 <br /> HH' West Phase 3 _ Waterline/WCR 23.5 250 , 50 from Property , 2.29 <br /> CONCLUSIONS <br /> Based on the stability analyses,the Phase 3(former Dersham Property)proposed extent of mining limits were greatly <br /> influenced favorably by the proposed 3:1 (H:V)mining slope. As a result,the minimum distances proposed are <br /> recommended more for construction and maintenance than for stability. <br /> LIMITATIONS <br /> Our review is based on regional geologic mapping,present mining plans,borehole data from the adjacent Baseline <br /> Resource property,and stability analyses using typical strength parameters for the various strata in the critical sections. <br /> Should the mining plans change or subsurface conditions vary from those portrayed in this letter,we should be <br /> contacted in order to re-evaluate the potential affects an permanent man-made structures. Stability analyses were run at <br /> the structure in question and were not run on failure surfaces closer to the highwall. Note also that surcharge loads due <br /> to temporary material stockpiles and overburden berms were not considered in the analysis. <br /> Please call with any questions or comments. <br /> Sincerely, <br /> Civil Resou ,LL /J� <br /> Ai( /�4,., & eg <br /> Mark Reins,P.E.,P.G. <br /> Project Engineer <br /> Attachments: Figure showing site location,boring and cross-section locations,and proposed extent of mining. Input <br /> and output files and graphic profiles of stability analyses are also included. <br /> J.iHallIn inl8asalk elStabiJty analysis repo/Edon <br />