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• be noted that the standazd Proctor values used to determine [he degree of compaction were obtained by <br />conducting check point Proctors on samples obtained during this investigation and then correlating them <br />to the Proctor values which were previously completed by our firm, as the waste coal materials were <br />placed and compacted. The maximum dry unit weights obtained from the Proctor tests ranged from 86.5 <br />pcf to 99.0 pcf and the optimum moisnue contents ranged from 14.0 to 18.5 percent <br />The strength chazacteristics of the processed waste coal materials were determined by conducting direct <br />shear tests on the remolded waste coal materials and by conducting unconfined compressive strength tests <br />on relatively undistwbed samples obtained from the test holes. The direct sheaz test results indicate that <br />the peak friction angle of a sample of the remolded waste coal materials, which had the higher amount of <br />fines, was 30.4 degrees at the in-situ moisture content and density. A cohesion value of 391 psf was also <br />obtained on this sample. The peak friction angle determined on the more granulaz waste coal materials <br />was 52.5 degrees with a cohesion value of 191 pcf. The unconfined compressive strengths obtained on <br />the samples indicated values ranging from 1,870 psf to 3,540 psf. The direct sheaz test results aze shown <br />in Figures #6 and #7 and the unconfined compressive strength test results are shown in Table 1. <br />Based on the results of the permeability tests conducted on samples of [he remolded waste coal materials, <br />• it appears dta[ the majority of these materials aze relatively impermeable with falling head permeability <br />rates ranging from 6.1 z 10-7 to 3.8 x 10-7 cm/sec. The permeability test results aze shown in Table l . <br />A thin layer of natural clay was encountered beneath the processed waste coal in test hole 2 at a depth of <br />34 feet. The clay layer was approximately 2 fee[ in thickness. The clays were sandy with occasional <br />gravels, low [o medium plastic, stiff, moist [o very moist and brown to gray in color. Claystone bedrock <br />was encountered below the waste coal materials in test hole l and below the natural clays in test hole 2 at <br />depths of 32.5 and 36 feet, respectively. The claystone bedrock was slightly sandy, medium [o highly <br />plastic, hard to very hazd, slightly moist to moist and brown to gray in color. <br />Water was not encountered in either of the test holes at the time of drilling. However, when measured 7 <br />and 33 days subsequent to drilling, water levels were encountered in both test holes. The water level in <br />test hole l varied from 31 to 34 feet in depth and the water level in test hole 2 varied from 21 to 26 fee[ <br />in depth. It should also be noted that we encountered a perched water level in test pit 2 at a depth of 5 <br />feet at the time the test pit was excavated. The water levels encountered along with the number days <br />after drilling that the measurements were taken, aze shown on the logs of the test pits and holes. It <br />should be noted that water levels can be expected to fluctuate with changes in precipitation and runoff. <br /> <br />Job No. 97-3216 Northwest Colorado Consullancs, Grc. Page 5 <br />