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<br />• <br />commended appropriate construction procedures for the rock waste <br />disposal facility. <br />Although no gradation curve is available for the material, <br />it is evident that the rock waste comprises a fairly good quali- <br />ty rockfill with a minor amount of fines. According to the Uni- <br />fied Classification System, it could probably be classified as a <br />silty gravel (GM) or possibly as a poorly graded gravel-sand mix- <br />ture with little fines (G P). <br />Lincoln DeVore performed Standard Proctor Tests (ASTM D- <br />69II). Their tests indicated a maximum density of 131.2 pcf. They <br />also performed triaxial tests with the material which was re- <br />molded at approximately 90 $ of the maximum density. The tests <br />indicated a friction angle ~ = 29 degrees and a cohesion C = <br />1,296 psf. As the large fragments of rock were removed for test- <br />ing, the results are very conservative. <br />Lincoln DeVore performed stability analyses of a slope not <br />exceeding 60 feet in height. The analyzed slope had two ten foot <br />wide benches included. The slope between the benches was 2(H) <br />1(V). -Other, flatter slopes were analyzed as well. As can be ex- <br />pected, the factors of safety were reasonably high. A minimum <br />factor of safety was found to be equal to 3.5. <br />Based on the results of these analyses, Lincoln DeVore <br />recommended to accept the analyzed slope configuration; they re- <br />commended to compact the outer shell of the waste pile to 90 $ of <br />Maximum Proctor Density. They also recommended to place the waste <br />in lifts not to exceed 12 inches Ioose thickness. Material <br />located beyond the outer shell of the pile was recommended to be <br />sprjad in lifts not exceeding two feet in thickness. No com- <br />paction was recommended for this zone of the facility. <br />Aiid-Continent proposed in their Permit Application trucking <br />of the tunnel spoil material to the disposal area and spreading <br />and compacting it according to these recommendations. <br />4.0 FIELD AND LABORATORY INVESTIGATION <br />4.1 COAL REFUSE DISPOSAL FACILITY <br />The coal refuse disposal facility was visited on April 18, <br />1984. The purpose of our visit was to visually inspect the ex- <br />isting coal refuse facility, to verify the construction methods, <br />to perform in-place moisture and density testing, and to obtain <br />samples for the determination of moisture and density relation- <br />ship. Testing was performed by Chen & Associates Laboratory in <br />G1 enwoed Springs. <br />1 6 <br />GEO-HYDRO CON <br />