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<br />Memo to Dave Berry <br />Bowie No. 2 Gob Pile Laboratory Testing <br />page 5 <br />that blow count correlations are an acceptable means to derive strength <br />parameters for the gob pile design." <br />The Division's Opinion <br />As originally stated in my adequacy comments, my experience leads me to <br />question the accuracy of observations based on blow counts. I further believe <br />that the triaxial shear determinations performed on the Mancos Shale in <br />MAXIM's laboratory appear to have been appropriately conducted. I fail to see <br />what a literature search will provide to improve upon the site specific <br />sampling and laboratory analysis. Laboratory analyses are normally performed <br />to provide site specific strength determinations, which will be more reliable <br />than experiential or literature determinations. <br />My first inclination would be to compare the blow count recordings completed <br />by WESTEC and MAXIM while obtaining their sample collection. Assuming that <br />all California samplers are manufactured to the same standard specifications, <br />the effort required during MAXIM's sampling should being comparative to that <br />exerted by WESTEC during it's original field sampling. If MAXIM and WESTEC <br />encountered significantly different sampling penetration resistance, the Mancos <br />Shale they each sampled may have been significantly different. The degree of <br />weathering, lateral support, and moisture content, may all effect the <br />penetration resistance of an earthen material. The Mancos Shale, commonly <br />containing smectitic clays, can be particularly sensitive to moisture variations <br />throughout its history. If the penetration effort expended by both samplers is <br />similar, however, I would conclude that the material sampled by both was <br />similar in density. If the penetration effort was dissimilar, I would conclude <br />that the materials sampled may have been dissimilar. Considerable variation <br />can occur both vertically and horizontally within any bedrock formation, both <br />because of lithology and weathering modifications. <br />To be fair, however, I must also observe that errors do occur in the laboratory. <br />The appropriate solution to a question of laboratory accuracy is to perform <br />comparative analyses in another laboratory. If sufficient specimen remains, <br />the Division would be receptive to consideration of a comparative laboratory <br />