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Memo to Joe Dudash Bowie #2 Waste Pile Inspection page 2 dry density. While not impossible, these relative compaction values are not probable. I suspect that the mixing of subsoil and/or dry coal waste with the wet coal waste, which you reported in your letter, is resulting in the creation of a hybrid waste material. The original proctor test performed on the unadulterated waste is no longer representative of the hybrid mixed waste material. This invalidates the original proctor analysis and any compaction determinations based upon that proctor standard. It is also possible that the mechanical properties of the unamended waste have changed. Further, it is also possible, depending upon the particular testing methodology used, that the results are invalid due to contamination of the tested sphere with coarse rock. The same problem appears to exist with the compaction test results reported within the July 16, 1998 (Second Quarter `98) inspection report. In this case, four of the eight compaction test results reported exceed 110% relative density, ranging from 1 13.4% to 122.1 % of the optimum dry density. These relative compaction results are even less probable than those of the first inspection. The operator must develop an acceptable methodology for verifying that the proctor standard being applied during a compaction test is appropriate for the materials being inspected. The brute force approach is to perform a proctor analysis every time a compaction testing is performed. That approach is expensive and time consuming, and normally unnecessary. Ofren, if concern exists on the part of the engineer in charge of the inspection, a sieve analysis may serve to determine mechanical similarity of the standard and the tested specimen. If the materials are shown to be similar in gradation, fine content, and visual constituency, they can be assumed to be representative. In some cases, however, it materials aze vaziant because of source variation or amendment, numerous proctors may need to be completed. Another common cause of compaction test inaccuracy is failure to properly analyze the constituency of the sample tested. Modem nuclear density testing standards are commonly misapplied. The nuclear probes measure the average density of a sphere approximately one foot in radius around the probe. If one or more coarse cobbles exist within that sphere, they will bias the compaction results upward. Standard methodology dictates that the operator excavate a one foot radius sphere after the probe reading is completed, in order to verify that the material tested is appropriately devoid of coazse materials. Frankly, many technicians fail to complete this important verification step. Further, if [he excavation determines that the test was biased by coarse material, it should repeated until successful. Many technicians lose interest after several attempts. The same concerns apply to older sand replacement testing methods. If coarse material exists within the volume of soil excavated during the test, the test should be repeated.