1987-12-01_PERMIT FILE - C1981017 (169)

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CONTRACTORS ENGINEERS DEVELOPERS 4�' � MORRISON-KNUDSEN COMP ZANY,INC. 06 EXECUTIVE OFFICE TWO MORRISON-KNUDSEN PLAZA / P.O.BOX 7808 / BOISE,IDAHO83729 / U.S.A. TELEX:368439 PHONE:(208)345-5000 June 3, 1977 LTC #8-1097 Mr. John Turner, Vice Pres. & Gen. Manager MID-CONTINENT COAL AND COKE COMPANY P. 0. Box 158 Carbondale, CO 81623 Dear Mr. Turner: As we discussed during our meeting on May 25, 1977, we are presenting our optimum program for sampling and testing of the coal refuse pile. The drilling and sampling program has been designed to satisfy the sampling requirements of both the refuse stability study and the coal refuse recovery study. The testing program presented is for the sta- bility study only. The testing requirements for the refuse coal re- covery study will be similar to those outlined in our June 1, 1977 • correspondence to you and will be accomplished to the greatest extent possible at Mid-Continent's laboratory. DRILLING AND SAMPLING PROGRAM An optimum sampling program to provide input data for the refuse stability study and the refuse coal recovery study should include a combination of drill holes and dozer trenches. Recommended approxi- mate drill hole_ locations are shown on the attached map. Due-to the possibility of encountering buried debris and changing.accessibility, final hole locations should be determined with the aid of Mid-Continent engineers prior to commencement of drilling. A minimum of six drill holes through the refuse material and into the soil foundation material may result in data adequate to evaluate the variability of the refuse material . These holes should be drilled and sampled on ten foot intervals. Each ten foot interval will yield approximately seven feet of drill cuttings (approx. 100 lbs. ) to be analyzed for the refuse coal recovery study and a three foot "undisturbed" sample to be used jointly for the stability study input data and the refuse coal recovery study. Approximately thirty feet should be drilled into the foundation material below the dump in each hole. This material would be used only for the stability study input data. In addition, four holes to about a thirty foot depth should be drilled and sampled in the area where refuse will be dumped in the future.