Laserfiche WebLink
Proctor test, after which the gradations were compared. This additional compaction resulted in the <br />percent passing the #4 sieve increasing from 52.4 to 62.6% and the percent passing the #200 sieve <br />ranged from 17.8 to 22.3% <br />Falling head hydraulic conductivity (permeability) tests were carried out on as- received material in <br />addition to pulverized material to determine how low the saturated permeability could possibly be in <br />the long term due to compaction, weather, and other effects. The initial test was performed on <br />material at 90% of standard Proctor dry density with a result of 9.9x10 -6 cm /s. Then, only material <br />passing the #200 sieve was compacted to 90% of estimated maximum dry density (using maximum <br />effort) resulting in a permeability of 3.1x10 -6 cm /s. This same material was then compacted using the <br />maximum effort with a result of 9.8x10-7 cm /s. It can be seen that smaller particle sizes and <br />increased compaction will reduce the permeability of the refuse material by about one order of <br />magnitude in extreme conditions. <br />Due to the material's classification as a granular material (SM), and the low likelihood that the <br />material will become saturated to an appreciable depth in the field, the drained strength envelope was <br />measured in the laboratory using the direct shear apparatus. A fully- softened direct shear was <br />performed on material finer than the #200 sieve and ball - milled to represent worst -case conditions in <br />which the material breaks down to very fine particles during placement and over time due to freeze - <br />thaw cycles and other weathering phenomena. The material used in the testing classified as a silt <br />(ML). The resulting fully- softened shear strength envelope was 33.8 degrees and an apparent <br />cohesion of 228 psf. Recognizing that the actual failure envelope is non - linear, this linear <br />approximation was used in the analysis for ease of computation. <br />2.2.2.2 Colluvium <br />As for the refuse material, bucket samples of colluvium were tested in the laboratory. These tests <br />included moisture content, Atterberg limits, standard Proctor, fully - softened direct shear, residual <br />direct shear, and consolidated - undrained triaxial shear. <br />The fully- softened shear strength is a peak drained shear strength envelope that simulates the <br />swelling and softening of a medium -stiff or stiffer fissured clay. While the degree of fissuring in the <br />colluvium is not well understood, it can be classified as a medium -stiff to stiff clay in which fissuring <br />could occur. For this reason, the fully- softened strength of the colluvium was tested using a direct <br />shear apparatus. The resulting fully- softened shear strength envelope from the six -point test was <br />24.9 degrees with an apparent cohesion of 330 psf. <br />P. \Mpls \06 C0126 \06261003 RPE E. Permit Mod Support\WorkFdes \Permit Apphcation \Text \Exhibrt 82 RPEE design 2011 -07 -21 TR 127 doc 8 <br />