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<br />e <br /> <br />6. l/2-inch fiber glass mat - same as No. 5 above, <br />except thicker and'more dense. May retard seed <br />germination and vegetation growth. <br /> <br />7. Excelsior mat - dried shredded wood held together <br />with a fine paper net and secured with steel pins. <br /> <br />~ <br /> <br />8. Straw with erosionet - chopped straw held in place <br />with Erosionet and steel pins. <br /> <br />~ <br /> <br />A more complete description of each temporary lining material is <br />presented along with the design charts. It should be ascertained <br />that the lining material being considered for use is nearly the <br />same as the material which was tested. Otherwise, the design <br />charts are not applicable. <br /> <br />Note that the stranded fiber glass roving was held in place <br />with Erosionet 315 in No. 4 above. This was due to the con- <br />figuration of the test channels used by MSU, which were <br />rectangular with smooth sidewalls. Additional research on <br />fiber glass roving as a channel lining material was performed <br />by the Louisiana Department of Highways as an HP&R study (4). <br />The results on erosion prevention were based on actual field <br />installations, while the hydraulic resistance results were from <br />laboratory flume experiments. It was concluded that the fiber <br />glass roving and asphalt should be applied at least 2 feet, <br />measured along the fllope, beyond the anticipated high water level <br />to prevent the tractive force of the flow from pulling the liner <br />from the side slopes of the channel. Naturally, this recommended <br />type of installation was not possible during the MSU tests in <br />rectangular channels with smooth sidewalls. <br /> <br />e <br /> <br />The Louisiana results include some limited field observations <br />of jute mesh channel linings which compare well with the <br />MSU results on the same material, and tend to confirm the <br />design charts of this circular. <br /> <br />. <br /> <br />The basic design method used in this circular, maximum <br />permissible depth of flow, was developed as a part of the <br />MSU research, and will be discussed in detail in the next <br />section of this circular. <br /> <br />'; <br /> <br />e <br /> <br />4 <br />