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0 2.05.3(4) Ponds, Impoundments and Diversions <br />sediment level will be measured by determining the depth to actual sediment level <br />measured down from the invert of the dewatering device, (S). This measurement will <br />be compared to the design sediment depth of the pond measured from the bottom of <br />the pond to the invert of the dewatering device, (D). The calculation of (D -S) *(100) /(D) <br />gives the percent of sediment accumulation. Sediment removal will occur when the <br />sediment level in the pond reaches 50 %. <br />In the construction of ponds A and B all vegetative and organic materials <br />were removed and foundations excavated and prepared to resist failure. All foundation <br />base areas were sloped no steeper than 1h:1v, and the entire foundation base was <br />scarified. Cutoff trenches were not installed. All fill material was free of sod, large roots, <br />other large vegetation matter, and frozen soil. Coal- processing waste was not used in <br />embankment construction. The placing and spreading of the fill material was started at <br />the lowest point of the foundation. The fill was brought up in 12 inch thick horizontal <br />layers. Hauling equipment was routed both ways over the fill and routing varied <br />sufficiently to achieve uniform compaction. Compaction was carried to the edge of the <br />fills so that the final slopes were firm. The minimum elevation of the top of the settled <br />embankment is 1.0 foot above the water surface in the ponds with the emergency <br />spillways flowing at design depth. The combined upstream and downstream side slopes <br />of the settled embankments are not steeper than 5h:1v, and no slopes are steeper than <br />2h:1v. <br />The upstream and downstream side slopes of the embankment of pond A <br />are 2h:1v and 5h:1v respectively. The upstream and downstream side slopes of the <br />embankment of pond B are 4h:1v and 5h:1v respectively. The design top width of all of <br />the embankments is 10 feet. <br />Faces of the embankments including the surrounding areas are vegetated <br />to enhance stability. Anti -seep collars were installed to control seepage along conduits <br />that extend through the embankments. <br />Ponds A and B are located in an ephemeral channel that flows into <br />Naturita Creek. There are no farm builds, agricultural land or county roads between the <br />ponds and Naturita Creek. Naturita Creek is judged to have sufficient capacity to <br />convey the flow from a pond failure into the San Miguel River without loss of life or <br />serious property damage. Ponds A and B are Class A dams which are defined as <br />dams located in rural or agricultural areas where failure may damage farm buildings, <br />agricultural land, or township and country roads. <br />TR -09 2.05 -8i 11/2010 <br />