Laserfiche WebLink
Attempts were made to measure the level of free groundwater in all <br />borings. Water was found only in boring TH-7 at a depth of 21 feet. fJo water was <br />detected in boring TH-I at the base of the proposed fill. <br />Representative samples of the near surface soil and The bedrock were <br />returned to our laboratory for testing. The results of consolidation tests on <br />samples of the valley bottom clays are presented on Figs. B-2 through B-4. An <br />undrained iriaxial test with pore pressure measurements was performed on <br />samples of The clay (Fig. B-I) and indicated the clay material exhibited cohesion <br />on the order of 500 psf with an angle of internal friction (phi) of about 15 <br />degrees. Unconfined compressive strengths of samples of stiff clay were on the <br />order of 6,000 psf. Samples of the sedimentary bedrock claystone/siltsTone were <br />also tested using unconfined compression tests. These Tests indicated cohesion in <br />the range of 3,000 to 15,000 psf. For stability analysis, we assumed a shear <br />strength angle of internal friction of IS° and cohesion of 500 psf for the clays. <br />The bedrock was assumed to have 5,000 psf cohesion and zero friction. <br />STABILITY ANALYSIS <br />Colowyo Coal Company personnel identified the approximate area of the <br />proposed spoil and indicated slopes would be 3:1 (Horizontal to vertical). We <br />anticipated there will be intermediate terraces approximately 20 to 30 feet wide <br />at 50 to 100 feet height intervals to control surface erosion and provide access. <br />R <br />