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<br />e <br /> <br />~ <br />. <br /> <br />. <br /> <br />e <br /> <br />~ <br /> <br />e <br /> <br />Unlined Channels <br /> <br />The design charts for unlined channels (bare soils) are based <br />on MSU tests on ten different classes of soils ranging from <br />cohesive clays to noncohesive sands and gravels. The <br />~ax - So curves are drawn to encompass the majority of the <br />data points. Generally, sandy, noncohesive soils tend to <br />be very erodible, the large grained gravel-clay-silt mixtures <br />are erosion resistant, and the mixtures of sand, clay, and <br />colloids are moderately erodible. More detail on the soils <br />tested may be found in the MSU report (3). <br /> <br />Fiber Glass Roving <br /> <br />Fiber glass roving is delivered as a lightly bound ribbon of <br />continuous glass fibers. The material is applied to the <br />channel bed using a special venturi nozzle driven by an air <br />compressor, which separates the fibers and results in a <br />web-like mat of glass fibers. The glass fibers are tacked <br />with asphalt for adhesion to each other and to the soil. <br /> <br />The single layer of fiber glass roving consists of one layer <br />of blown fiber glass fibers applied at a minimum rate of <br />0.25 potmd per square yard tacked with asphalt emulsion or <br />asphalt cement at a minimum rate of 0.25 gallon per square <br />yard. <br /> <br />The double layer application consists of two alternating <br />layers of fiber glass and asphalt, each layer consisting of <br />fiber glass roving at 0.25 pound per square yard and asphalt <br />of 0.25 gallon per square yard. <br /> <br />Jute Mesh <br /> <br />Jute mesh is a mat lining woven of jute yarn which varies <br />from 1/8- to 1/4-inch in diameter. The mat weighs <br />approximately 0.80 pound per square yard, with openings <br />about 3/8-inch by 3/4-inch. <br /> <br />Steel pins or staples are used to hold the jute mesh in <br />place. A typical stapling configuration is shown in <br />Figure 4. The pins or staples should be spaced not more <br />than 3 feet apart in 3 rows for each strip, with one row <br />along each edge and one row alternately spaced in the <br />center. At the overlapping edges of parallel strips, staples <br />should be spaced at 2 feet or less. At all anchor slots, <br />jtmction slots, and check slots, spacing should be 6 inches <br />or less. <br /> <br />21 <br />