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• A description of the construction methods to be employed in the construction of the Horse Fill <br />• K Area Buttress - Plan View <br />• K Area Buttress - Cross Sections (9) <br />• A description of the construction methods to be employed in the construction of the K area <br />buttress <br />This information is included in a new appendix known as Appendix T, Horse and Buttress Fill Design <br />Information. The Table of Contents (page i-14-enclosed) has been revised to include this new <br />appendix. <br />Division's initial response: ...Rule 2.05.3(6)(b) requires the submittal of descriptions of proposed <br />disposal sites and designs of proposed disposal sites and designs of proposed spoil disposal structures <br />that affect the applicable requirements of Rule 4.09. Rules 2.05.3(6)(b) and 2.05.3(6)(c) additionally <br />specifically require the submittal of results of geotechnical investigations of proposed spoil disposal <br />sites and structures. Please submit the results of the geotechnical investigations conducted in <br />accordance with the requirements of the rules for Horse Gulch Fill site and structure and the K Area <br />Buttress Fill site and structure. <br />Trapper Mining, Inc. 's response: Enclosed you will find two certified reports prepared by AAI. <br />These reports are entitled "Horse Gulch Fill Stability Analysis" and "K-Pit Buttress Fill Stability <br />Analysis." These reports will be inserted into Appendix T in Trapper's permit document. Material <br />properties were derived from field investigations and core hole data. Material properties from <br />geotechnical investigations are discussed in section 2 of both reports. <br />Division's response: This response is Complete. <br />Division's initial comment No. 3: The east panel area has experienced mass movement as a result of <br />geologic structure and mining operations. Please provide stability predictions for K pit, Buttress fill <br />and G-dip backfill. (Rule 4.14.1(2)(9a) and 4.14. 1 (f)(ii)). <br />Trapper Mining Inc. 's initial response: Agapito Associates Inc. has completed the final draft of a <br />report entitled "Trapper G-Pit Landslide Mining Assessment - January 2008". This report discusses <br />much of the work that has been done with regard to coring, testing, and modeling. Section 4 of this <br />report address spoil stability in K pit where the combination of anomalously steep slopes and a weak <br />pit floor (Q seam floor) put limits on how much material (spoil) can be safely placed in this pit. <br />Section 4.5, Spoil Pile Recommendations, discusses specific recommendations. For the average dip <br />condition in K pit (13° , 23%) a maximum fill height of 68 feet above the toe and a slope not <br />exceeding 1.3(H:V) are recommended. Where areas of K pit have steeper dips, up to 55 feet of spoil <br />can be placed with proper treatment of the pit floor. In any event, the spoils should be placed so that <br />they drain, as the model assumes that the majority of the spoil pile is drained. G pit spoils are not <br />specifically discussed; however, the structure is not as severe. Section 5 of the report discusses the <br />proposed mine plan. Worthy of note is the importance of placing a buttress at the toe of the landslide <br />to provide resistance to future movement (page56). As stated above, formal geotechnical designs for <br />the Buttress are planed for 2008 but are not yet available. A copy of the Agapito report referenced <br />above is attached. Please respect the proprietary nature of this report.