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S ~+„ • • <br />picture within the Reclamation Permit of how the post-mining lands <br />will appear. <br />Relocated Carlton Tails Underdrain <br />The most recent version of Volume I - Amendment 6 persists in <br />discussing a drainage layer under the relocated tails consisting of <br />a 2 foot thick layer "composed of overburden rock which currently <br />exists within the valley as a by-product of previous mining <br />activity" (pages 5-30 and 5-31). This aspect of the design was <br />clearly eliminated in the applicants submittal titled "Response to <br />Third Party Technical Review". Also, design details for the <br />Carlton Tails underdrain are specifically addressed in my memo to <br />you dated March 16, 1994. The applicant should respond to the <br />contents of that memo. <br />Assumed versus Measured Material Strength Values <br />Certain language and phraseology selected by the applicant requires <br />a response by the Division in order to prevent an erosion of our <br />ability to regulate that may be caused by accepting such language <br />and phraseology without responding. That is why I am including <br />this paragraph on assumed vs. measured material strength values, in <br />the hope that we can avoid having to prepare voluminous findings <br />when certain regulatory requirements are questioned by applicants <br />and operators. It would not be difficult to locate detailed <br />information to prepare a specific finding regarding the subject of <br />this paragraph, but it is hoped that the applicant will accept the <br />Division's stance that 25 to 50 million ton fills will" not be <br />approved without laboratory testing of material strength <br />properties. <br />On page 5-31 of the most recent version of Volume I - Amendment 6, <br />the applicant states that material strength parameters determined <br />by field observation methods as opposed to laboratory testing, are <br />"universally accepted". The Division does not agree that these <br />methods are universally accepted. In the same paragraph, the <br />applicant states that "test results confirm the use of the internal <br />angle of friction and cohesion in that the test values were higher <br />than the values used". In fact, in the case of the Cresson waste <br />rock, the tested friction angle of 38 degrees was lower than the <br />assumed value of 39 degrees utilized in some of the stability <br />analyses. That alone confirms the appropriateness of the <br />laboratory testing requirement, in that the friction angle of 39 <br />degrees for the waste rock had been touted as conservative, but in <br />fact was not. <br />cc: Carl Mount <br />Jim Pendleton <br />Harry Posey <br />Bill York-Feirn <br />C:\WP51\CRESSON2 <br />