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Acz <br />• <br />AC2 Inc. <br />Englneering and Envlronmentel Services <br />ta75 Pine Grove goad. Suite t09 <br />P.O. Box 774078 <br />Steamboat Springs, Colorado 80477 <br />303.879.6260 <br />~'+ ~- <br />C ~ ~ sa ~ j.-,a <br />APR 6 199: <br />April 3, 1992 <br />Ms. Cathy Begej <br />Mined [.and Reclamation Division <br />1313 Sherman Street, Room 215 <br />Denver, Colorado 80203 <br />Mined sand <br />~o.+h..,o,fnr rY • .. .. <br />Re: EFCI Southfield Mine (C-81-014), Technical Revision ('CR-14) for Reevaluation of Coal <br />Refuse Pile Stability <br />Deaz Ms. Begej: <br />Accompanying this letter aze three copies of a Technical Revision Application addressing <br />reevaluation of the stability analysis for the existing coal refuse stockpile. The technical revision <br />• (TR-l4) responds to specific Division concerns relative to vaziances in refuse placement practices <br />and consequent effects on refuse pile stability. This submittal is also designed to provide for full <br />abatement of NOV C-92-01. <br />With respect to Condition 1 of the NOV, EFCI completed remedial grading activities prior to the <br />corresponding February 13, 1992 abatement date to insure effective drainage from the pile surface. <br />This submittal addresses NOV Conditions 2 and 3, providing the results of field sampling, material <br />testing, and revaluation of stability modeling input pazameters and results relative to actual <br />measured material physical properties. Reevaluation of refuse pile stability resulted in a <br />determination that the existing pile configuration and placement prattices aze consistent with <br />applicable regulatory requirements. Modification of the pile and/or changes in refuse placement <br />methods aze, therefore, unwarranted and Condition 4 of the NOV is no longer applicable. <br />This submittal consists of the following specific components and is designed as a complete <br />descriptive package for placement in Exhibit I5, Minor and Technical Revisions: <br />• Technical Revision Application Form; <br />• Proposed Public Notice; <br />• Refuse Pile Stability Report (1/14/92); <br />- Attachment A, XSTABL Computer Printouts <br />• - Attachment B, Proposed Plan for Determination and Evaluation of Coal <br />Refuse Plasticity Values <br />- Attachment C, Coal Refuse Plasticity Results and Related Stability <br />Implications <br />- Attachment D, 1988 Refuse Pile Stability Evaluation <br />