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5.2 Interior Slopes <br />0 4 � - y Huddteston -Berry <br />� RnYl�srti�.Y t'IafwE LLl <br />• C <br />The slope stability analyses for the interior pit slopes were conducted for the <br />proposed finished slope angle of 3H:1 V. As shown in the results included in Appendix <br />B, the minimum factor -of- safety for the proposed finished interior slopes is 2.6. This is <br />significantly higher than the generally required minimum factor -of- safety of 1.3 to 1.5. <br />5.3 Detention Ponds <br />As shown on Figure 3 — Pond Details, the proposed embankment dams for the <br />detention ponds will be constructed with slopes of 3H:1V. In addition, the dams are <br />proposed to detain a maximum of 4 feet of stormwater. While seepage forces were not <br />considered, a sloping water table was included in the model for conservatism <br />The results of the stability analyses included in Appendix B indicate a minimum <br />factor -of- safety of 1.8 against global stability failure. This is higher than the typically <br />required minimum factor -of- safety of between 1.3 and 1.5 for long -term stability. <br />6.0 CONCLUSIONS <br />Based upon the available data sources, field reconnaissance, and results of the <br />stability analyses, HBET does not believe that there are any geologic conditions which <br />should preclude gravel resource extraction in the western portion of the site. <br />7.0 GENERAL <br />The conclusions included above are based upon the results of the field <br />reconnaissance and on our local experience. These conclusions are valid only for the <br />proposed construction. <br />As discussed previously, the proposed resource extraction in the western portion <br />of the site is not anticipated to adversely impact Highway 141. However, it is <br />recommended that HBET be retained to provide engineering oversight during the mining <br />to verify compliance with the mining plan or permit identification of significant <br />variations in the subsurface conditions which may" require modification of the stability <br />analyses. <br />Huddleston -Berry Engineering and Testing, LLC is pleased to be of service to <br />your project. Please contact us if you have any questions or comments regarding the <br />contents of this report. <br />Respectfully Submitted: <br />Huddleston -Berry Engineering and Testing, LL <br />Michael A. Berry, P.E. <br />Vice President of Engineering <br />WA2008 ALL PROJECTS \00966 - Moores Mining, LLC \00966 -0001 Moores Pit\200 - Geo \00966 -0001 R030310.doc 4 <br />