Laserfiche WebLink
C <br />C~ <br />Groundwater seepage was not encountered in the test holes at the time of drilling or when measured 1 to 4 <br />days after drilling. However, it should be noted that the groundwater conditions at the site can be expected <br />to fluctuate with changes in precipitation and runoff. <br />Roadway Gravel Section Recommendations: It is our understanding that the new access road will <br />generally be subjected to low traffic volumes typically consisting of pickup trucks with occasional <br />delivery/haul trucks during construction of the shaft or support structures. Therefore, we have assumed an <br />18-kip equivalent single axle loading (ESAL) of 3,000 for the access road. Based on the field investigation <br />and laboratory test results, we have correlated a soils resilient modulus of 5000 psi for the on-site materials. <br />Based on the subsurface conditions encountered across the site, the assumed traffic loadings and our <br />experience with similaz projects, we recommend that the Bleeder Shaft access roadway be constructed with <br />a gravel section consisting of 3 inches of base course gravels and a minimum of 8 inches of subbase (pit <br />run) gravels. An alternate section would consist of 6 inches of pit run gravels and 4 inches of base course <br />gravels. These gravel sections should be placed on the natural soils or properly compacted subgrade fill <br />materials after the topsoil and organic materials have bee removed. We have assumed that all of the topsoil <br />and organic materials will be removed prior to placing the gravels or embankment fill materials. If the <br />client elects to leave the topsoil and organic materials in-place and place the gravel section over a <br />• geotextile/stabilization fabric, such as Mirafi 600X or equivalent product, then the subbase gravel sections <br />should be increased by 12 inches. This would result in a total subbase gravel thickness of 18 to 20 inches. <br />Site Gradine Recommendations: We recommend that roadway and pad cut and fill slopes be constructed <br />to a 2 (Horizontal) to 1 (Vertical) or flatter slope configuration. Flatter slopes are often desirable in chat <br />they allow for easier revegetation of disturbed areas and reduce erosion and siltation, which often occurs <br />with newly constructed cuts and fills. It should be noted that cut slopes constructed in the bedrock materials <br />could be excavated to 1 (H) : 1(V) configuration and be stable. However, it will not be feasible to <br />revegatate these slopes. [f groundwater seepage is encountered in any finished cut slope, we should be <br />notified to evaluate these areas to determine if additional stabilization measures are required. <br />The roadway subgrade should be prepared by stripping of all topsoil and organic materials. Based on the <br />limited amount of topsoil and organic materials across the site, it appears that the removal of the topsoil and <br />organic materials will be more economically feasible than leaving the topsoil and organic materials in place <br />and using a geotextile/stabilization fabric. <br />The exposed roadway subgrade surfaces should be scarified to a minimum depth of approximately 12 <br />inches, moisture conditioned to near the optimum moisture content and then be recompacted to at (east 95% <br />of the maximum standard Proctor density (SPD), as determined by ASTM D698. Suitable subgrade fill <br />materials will consist of the on-site soils and bedrock materials, which should be uniformly placed and <br />• compacted in 8 to l2-inch layers to at least 95% SPD, near optimum moisture content. <br />Job Number: 03-5838 NWCC, Inc. Page 3 <br />