REP41945 - Laserfiche WebLink

Home Browse Search

J. J. Dudash - 2 - Auqusi 28, 1998 exceed 100% relative compaction. On the contrary, a higher relative compaction translates into astronger in-place material which results in a gob pile with a greater safety factor. There are approximately 11,500 cubic yards of subsoil stored in the coverfill stockpile. BRL is currently excavating material from the gob pile founding and placing cover material on the ouslope of the pile. This contemporaneous reclamation effort, which will be ongoing, will supplement the material stored in the coverfill pile. 4. The DMG noted that as of February 24, 1998, the gob pile was approximately 20-feet high and no compaction tests had been performed on the pile. The DMG believes that it is good engineering practice to confirm the compaction efforts, especially for the initial toe material and especially when the material properties of that material may have been altered by excess moisture or the addition of subsoil. BRL is developing a plan to determine the relative compaction of the initial toe material. However, any such plan has a number of risks. One method to determine the compaction is to drill to predetermined depths and obtain relatively undisturbed samples with a split spoon sampler. The split spoon sample may or may not be representative of the in-place target material since rocks or large chunks of coal can deflect or plug the tube. Another method is to drill a hole and run a density probe for the full depth of the target material. BRL has not decided which method to utilize. In fact, BRL may conclude the DMG does not have regulatory authority to request the subject tests. 5. The DMG requests assurance the underdrain material meets the grain size distribution listed on page 8 of Volume IV. Enclosed is a sieve analysis report prepared by underdrain material supplier, Delta Sand and Gravel. Please let me know if you have any questions. Sincerely, ~~' i - -- - J. E. Stover, P.E. Consulting Engineer cc: Wm. A. Bear, Jr.