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material being placed. Whether or not one or several test samples are token for <br />analyses depends on whether the material in the gob pile is homogeneous or <br />strntified. Jn this way, a comparison can be made between the properties of the <br />coal waste material and the properties of the composite material. With this <br />comparison, it can be determined whether or not additional laboratory tests and <br />an nccompanying slope stability analysis need be completed. Please comment. <br />BRL submitted the first quarter and second quarter gob pile inspection reports. <br />Apparently, BRL has run a new proctor test on the gob material, since the second <br />quarter report is based upon a different proctor test than was the first quarter <br />report, since different standards are referenced. No mention of a new materials <br />properties test was given. Please explain the details of this second proctor test and, <br />if applicable, of the materials properties test. <br />The Division is concerned that neither of the proctor standards referenced within <br />the two quarterly reports may be representative of the specific amended waste <br />materials being inspected. The April 24, 1998 (First Quarter `98) waste pile <br />inspection report presents the results of eleven compaction tests performed on the <br />pile. Five of these eleven tests determined relative densities to exceed 110%, <br />ranging between 110.3% and 117% of the optimum dry density. While not <br />impossible, these relative compaction values are not probable. The possibility <br />exists that the mixing of subsoil and/or dry coal waste with the wet coal waste, <br />which had been observed during the February 24, 1998 field inspection, is <br />resulting in the creation of a hybrid waste material. If this is true, then the original <br />proctor test performed on the unadulterated waste is no longer representative of the <br />hybrid mixed waste material. This would invalidate the original proctor analysis <br />and any compaction determinations based upon that proctor standard. It is <br />possible that the mechanical properties of the unamended waste have changed. It <br />is also possible that the results are invalid due to contamination of the tested sphere <br />with coarse rock, depending upon the particular testing methodology used. The <br />same problem appears to exist with the compaction test results reported within the <br />July 16, 1998 (Second Quarter `98) inspection report. In this case, four of the <br />eight compaction test results reported exceed 110% relative density, ranging from <br />113.4% to 122.1% of the optimum dry density. These relative compaction results <br />are even less probable than those of the first inspection. <br />The Division is concerned that the compaction tests may not be accurate or <br />representative of the material in the gob pile. The Division requests that BRL <br />examine the methodology used in performing the compaction testing, given the <br />2 <br />