Laserfiche WebLink
• Avoid potential problem areas as may be manifest through steep, unconsolidated slopes <br />and areas of groundwater seepage. <br />• Facilitate surface and groundwater drainage by providing unobstructed conveyance <br />structures and drainage systems. <br />• Minimize azea of soil and vegetation disturbance. <br />• Minimize depth of cuts and height of fills. <br />• Utilize support structures where feasible to reinforce potentially unstable materials, <br />protect against slope failures, and minimize the extent of lateral disturbance. <br />• Stabilize the channel of Sylvester Gulch where needed to prevent erosion in the form of <br />under cutting and down cutting. <br />Design Criteria <br />Recognizing the above outlined considerations, the following design criteria have been <br />developed. <br />1. Roadway width. The area of disturbance, cost of slope stabilization, cut/fill volumes, and <br />ease of controlling drainage and erosion aze all influenced by roadway width. It is <br />recommended that the minimum acceptable width be used in construction of the Sylvester <br />Gulch access road. A width of 12 feet is suggested with periodic pull-outs to allow for safe <br />passage of two-way traffic. Guard rails should be used where needed to provide safety. <br />2. Profile gradient. Preliminary analysis of the topography implies that most of the roadway <br />can be constructed at a grade of less than ] 0%. Where steeper grades are needed, they <br />should be as short as possible and located on straight sections of roadway. <br />3. Cross slope. Eliminate the hillside borrow ditch by pitching the cross slope of the roadway <br />towazds Sylvester Gulch. This will facilitate a narrow road width and prevent erosion and/or <br />infiltration of water in the borrow ditch. This also will reduce the potential for saturation of <br />subgrade material. If a normal crowned section is required, the hillside borrow ditch should <br />be made as small as practical. <br />4. Alignment. The roadway alignment should be located to accomplish the objectives listed in <br />#1, above. Generally, the alignment should be on the right side of the gulch to about station <br />28+00 and then cross to the left side, not crossing back to the right until near its junction with <br />the existing road at about station 56+00. <br />5. Drainage structures conveying the Sylvester Gulch flow should be capable of handling the <br />volumes and velocities determined in our drainage calculations. Where the existing channel <br />must be reconfigured, it should have a 2-foot-wide bottom with side slopes of 2:1. Riprap or <br />some other form of channel stabilization may be required to prevent erosion and scour. <br />Preliminary design drawings. <br />Drawings showing a preliminary roadway alignment, profile, cross sections, and construction <br />details have been prepazed and are shown on the accompanying, sheets 1 through 5. These <br />drawings have been developed using available topographic maps having contour intervals of 10 <br />and 20 feet. Because of the coarse contour intervals, the accuracy of the drawings must be <br />considered sufficient only for schematic evaluation. They do, however, show that an acceptable <br />alignment and grade appear to be attainable. <br />Additional field data is needed in order to proceed with a further evaluation of the feasibility to <br />construct an access road up Sylvester Gulch. This includes a detailed survey to better identify <br />Sylvester Gulch Road Feasibility, Preliminary Report <br />Job No. OI-345 <br />Page 3 of 4 <br />