Laserfiche WebLink
r <br /> Reply to Adequacy Review Comment on Coal Waste Pile <br /> The existing coal processing waste pile at Coal Basin has not <br /> experienced an episode of significant slope instability . The. <br /> episode of April 8 , 1979 was due to the cosmetic application <br /> of some refuse and soil in a reclamation program that occured <br /> late (Nov . ) in 1978 . The area in question was adjacent to <br /> the refuse belt conveyor and facing the office , bathhouse <br /> complex . It was the company ' s desire to revegetate this area <br /> in the fall in order that it would have an opportunity to <br /> utilize the winter moisture for growth in the spring . The <br /> area was quickly clone (in fact finished in a snow storm) . <br /> The drainage system was not completed properly which in the <br /> spring allowed all of the drainage to go to this area and <br /> collect rather than into the normal drainage pattern of the <br /> pile . The result was a saturation of this loose material <br /> that had been placed the previous fall and a slump occured . <br /> This area has a slope of approximately 3 to 1 or flatter <br /> than any part of the refuse pile . No structural failure has <br /> ever occured in the main formation of the refuse pile . <br /> Ceotechnical analysis has been accomplished in a study by <br /> Morrison-Knudsen which has been added as Appendix II-B-7 . <br /> A portion of the coal processing waste bank existed prior <br /> to the permanent program inception ( 1956 to 1977 ) . This <br /> portion of the pile has not been used or changed since the <br /> permanent program . It has been studied (see Morrison-Knudsen <br /> Creport) and found to be stable . It has been under an extensive <br /> revegetation program since 1974 . The company feels that this <br /> portion of the coal processing waste bank is pre-law thus <br /> grandfathered and plans no changes in its configuration . <br /> In compliance with the June 18 , 1981 Review comments by <br /> Jim Pendleton, the assumptions in the Morrison-Knudsen study <br /> concerning hydrology of the waste pile site will be verified <br /> by appropriate drilling and monitor well installation . This <br /> program will answer questions as to the depth of the water table <br /> within the waste disposal site and whether or not ground water <br /> has has invaded the waste pile and affected the materials <br /> strength of rile disposed waste . A copy of the Wahler and <br /> Associates , Inc . testing results has been furnished to MLRD . <br /> The precise locations of the drill hole locations and monitoring <br /> sites are indicated on revised Exhibit 11-B-7 . A stability <br /> analysis plan of the waste pile will be submitted by March 1 , <br /> 1982 . Any modifications in the planned configuration of the <br /> waste pile will also be submitted . <br /> v <br /> t b <br />