Laserfiche WebLink
INTEROFFICE MEMORANDUM <br />Date: 28 April 2009 <br />To: Jason D. Musick <br />From: Marcia L. Talvitie <br />Subject: Trapper Mine - Permit No. C-1981-010 <br />PR-06 - Horse Gulch Fill and K-Pit Buttress Fill <br />Adequacy Review - Engineering <br />Per your request, I have reviewed pertinent portions of the most recent PR-06 application <br />submitted by Trapper Mining, Inc. (TMI). My review focused on engineering aspects of the <br />proposed permit revision, specifically with respect to the Horse Gulch (HG) Fill and the K-Pit <br />Buttress (K-Pit) Fill. <br />TMI has contracted with Agapito Associates, Inc. (AAI) to conduct stability analyses of the HG <br />and K-Pit Fills. These two reports (intended for inclusion in Permit Appendix T), along with the <br />revised pages of the permit provided, were evaluated for compliance with the rules and <br />regulations of the Mined Land Reclamation Board. <br />The HG and K-Pit Fills, because they will be permanent features and will result in a departure <br />from approximate original contour, are classified as "Excess Spoil", and governed by Rule 4.09. <br />In addition, the requirements of 4.09.2 - Valley Fill will apply to the HG Fill. The HG Fill may <br />also be termed a Head of Hollow fill, per 4.09.3. However, no rock-core chimney drain system <br />has been proposed for the site. <br />Rule 4.09.1- Disposal of Excess Spoil - General Requirement <br />4.09.1(10) requires that where the slope in the disposal area is steeper than 2.8h: Iv (36 <br />percent), or such lesser slope as may be designated by the Division based on local <br />conditions, keyway cuts (excavations to stable bedrock) or rock toe buttresses shall be <br />constructed to stabilize the fill. Where the toe of the spoil rests on a downslope, stability <br />analyses shall be performed in accordance with 2.05.3(6)(b), (c) and (d) to determine the <br />size of the rock toe buttresses and keyway cuts.