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Page 2 of 3 <br />The Division acknowledges that tasks using a ripper to loosen material should not employ an <br />additional material consistency correction. The ripping task already loosens the material, <br />resulting in greater efficiency. The Division concurs with using a material consistency of at <br />least 1.0 when the ripping portion of the task (i.e. dozing or grading) is 50% or higher. This <br />correction would not be applicable to "ripper" tasks. The Division will revise the appropriate <br />tasks in the Division's RCE using this assumption. <br />29. NECC provided material weights for onsite conditions at the New Elk Mine. NECC used two <br />different methods for determining material weights. Both are valid methods. NECC proposes <br />to use the results from the method two. The Division accepts the material weights provided in <br />calculation method two (page 4) and will use these material weights in the RCE. <br />For comparison: <br />Material weight data provided by NECC (lbs /CY) <br />a. Clean coal 1457 <br />b. Washed Coal Refuse 1916 <br />c. Topsoil 2055 <br />d. Subsoil 2132 <br />e. Gravel products 2396 <br />Material weiaht data Cat Handbook 40th ed. (lbs /CY <br />a. <br />Clean coal <br />1400 <br />b. <br />Decomposed rock(25 %/75 %) <br />2650 <br />c. <br />Earth -loam <br />2100 <br />d. <br />Earth -dry packed <br />2550 <br />e. <br />Gravel -dry <br />2550 <br />30. In Section 3.0, page 4, NECC proposes that the vegetation failure rate should be reduced to <br />15% based on reclamation experience at one mine adjacent to the New Elk Mine. The Division <br />disagrees with this projection. The Division recognized the reclamation success at the Golden <br />Eagle mine, and approved final bond release on all but a very small acreage. The assertion that <br />revegetation success at the Golden Eagle Mine should be interpreted to mean that NECC will <br />have the same degree of success at the New Elk Mine is analogous to asserting that an area will <br />not experience a 25 year event in the projected liability time frame if it has not experienced an <br />anticipated 25 year precipitation event in the preceding 25 years. The failure rate ascribed to the <br />revegetation tasks represents a predicted probability for failure. <br />The Division considered NECC's argument previously and has already reduced the anticipated <br />failure rate from 50% (based upon interviews with County Extension personnel in 1995) to <br />33 %, based upon NRCS soil survey for Las Animas County. (See DRMS 2/1/2013 memo <br />regarding MT6 cost estimate update). <br />The Division has reviewed failure rates applied at other mine sites throughout the state, along <br />with average annual precipitation values and seed mixes. Based on this review, the Division <br />disagrees with NECC's proposal to reduce the revegetation failure rate to 15% (see table 1). <br />Since NECC has not provided valid supporting data or written recommendation by federal, <br />state, or local agencies that would support reducing the revegetation failure rate to a value less <br />than 33 %, the Division will continue to use a 33% failure rate in the RCE vegetation tasks. <br />If NECC believes that areas at the New Elk mine that have previously been seeded with the <br />permanent seed mix are eligible for bond release, NECC should submit a bond release <br />application to the Division for these areas. <br />