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C-2008-086 <br />PAR - MLT <br />27-Jan-2009 <br />Page 3 of 5 <br />13. Roadways constructed of and/or upon weathered Mancos shale are known to be <br />difficult to maintain if strict moisture/density compaction control methods are not <br />employed during construction. If insufficient moisture is introduced into the <br />roadbed during construction, and insufficient compaction is obtained, the shale <br />will tend to draw up moisture on its own, with an undulating road surface being <br />the result. The Division does not agree that 90% compaction (page 2.05-22) is <br />sufficient. Please modify the text to require 95% of the Standard Proctor method <br />(AASHTO T99), within 2% of the optimum moisture content for all roadway <br />embankments. <br />Rule 4.05.9 Impoundments <br />14. Rule 4.05.9(9) requires that where water will be impounded, the upstream face of <br />the embankment shall be riprapped or otherwise stabilized... if necessary to <br />protect against erosion from water or wind action, or sudden drawdown. Given <br />the climate and soils present in the permit area, the Division questions whether or <br />not a vegetation cover sufficient to stabilize the embankment slope can be <br />established and maintained. Please describe the stabilization measures proposed <br />for the upstream face of the pond embankments. <br />Rule 4.10 Coal Mine Waste Banks <br />15. Rule 4.10.4(3)(c) requires that compaction testing shall be performed to verify <br />that the minimum required compaction is achieved. Page 2.05-49 of the permit <br />application states that Compaction tests will be taken, "not less than one per every <br />other layer, at random locations across the pile." Where the 24" thick layers are <br />of limited extent, this frequency may be sufficient, but given the size of the pile <br />footprint, a single layer could consist of more than 100,000 tons of coal, mine <br />waste. The Division does not agree that the proposed frequency will be adequate <br />in all cases. In addition to the "vertical "frequency, please propose an additional <br />testing frequency based upon the tonnage placed. <br />Volume I - Text - UE. Stover - 22-Apr-2008) <br />16. Section 2.05.4(2)(c), in the second paragraph, directs the reader to Volume VII <br />(should be Volume V) Geotechnical Studies analysis of fill slopes using weathered <br />shale and overburden. The Division's copy of Volume V does not include any <br />discussion of overburden samples that have been remolded for determination of <br />optimum moisture content, maximum dry density, etc. Volume V, Appendix 7, <br />does provide data for remolded shale, and an analysis of cut and fill stability using <br />this material. Please provide the Division with a discussion and tabular <br />presentation of the laboratory compaction (standard Proctor) analyses of <br />overburden for inclusion in Volume V, or revise the text as appropriate.