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Engineering Construction Report for No. 7 Shaft Cap at Climax Mine by Ellis Environmental Engineering, Inc., February 2003 <br />5.0 Results and Conclusions <br />In order to demonstrate the structural integrity of the No. 7 Shaft cap, the following <br />results are provided: <br />The fill materials around the shaft cap were found to have a soil pH of 7.6 and an acid <br />generation potential of 3 tons CaCO3 per 1000 tons compared to a net neutralization <br />potential of 12 tons CaCO3 per 1000 tons. Therefore, the soils should not be corrosive to <br />the steel supports or the steel re -bar in the structure. See Appendix 2. <br />Results of the concrete compressive strength tests are 3120 psi (SE corner), 4160 psi (NE <br />corner), and 3640 (SW corner). The integrity of the concrete cap was examined by the <br />author 6 years following construction and two years following testing. No cracks were <br />noted in the slab and it appeared to be in very good condition. Given the fact that the slab <br />will not be subjected to any additional loading, the existing concrete is adequate for the <br />structural cap. See Appendix 3. <br />To evaluate the cap's stability, calculations for deflection of the steel - reinforced concrete <br />slab were performed. See Appendix 4 for deflection computations. Under the worst case <br />scenario whereby the weight of the cap is distributed evenly over the center I -beam, the <br />deflection in the center of the cap was found to be on the order of 5.8 inches with no <br />additional loading on the slab. Given the fact that no cracking has been observed to date, <br />this deflection calculation plus field observations would indicate the slab is stable. <br />Careful examination of the construction photographs, review of field notes by the author, <br />combined with interviews with Mr. Romig and Mr. Kannegaard indicate the structure <br />was built according to plan. Therefore, the drawing in Appendix 5 will serve as the best <br />available as -built for the No. 7 Shaft. <br />6.0 Engineering Certification: <br />I, Michael D. Ellis, having reviewed the files, documents, photographs, drawings, and <br />data collected for the construction of the No. 7 Shaft at Climax Mine, hereby certify the <br />as -built construction and integrity of the structure. This certification applies to the shaft <br />cap in -place on the date of certification. If any substantial structural changes are made to <br />the shaft's reinforced concrete slab or the ground surrounding it, then this certification no <br />longer applies. <br />71/1-a-44( <br />Michael D. Ellis, P.E. <br />Colorado Registration No. 27101 <br />3 <br />