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-2- <br /> <br />3. Vegetation: The dominant vegetation on the pond site consists almost <br />entirely of Basin Wildrye Elymus cinereus with a scattered understory of <br />Big Sagebrush Artemisia tridentata and a few other minor species. <br />4. Land Use: Current land use in the area is coal mining on the adjacent <br />ridge, wildlife habitat, ran;alend, and pasture land a'.ong the floodplain <br />of Good Spring Creek. <br />Pond Design <br /> <br />Hydrology calculations for the Gulch A Pond were dcne by Tipton & <br />-Kalmbach, :Inc. and submitted .to the Division in the original permit application. <br />During the Division's adequacy review of the permit, some specific concerns in <br />the methodology for hydrology calculations were noted and included in the <br />Division's adequacy letter to Colowyo. Copies of the data from the permit <br />application and copies of the concerns of the Division along with Colowyo's <br />response and data backup taken from Vol. 8 of the Colowyo Permit, are included. <br />In addition to the changes proposed in Vol. 8, Colowyo feels the <br />following chances in original design are necessary from both an operational <br />and regulatory compliance standpoint: <br />1. The downstream side of the dam will be cov_red with rip rap to protect <br />the toe of the dzm from the possibility of .Good Spring Creek cutting in <br />that direction. <br />2. The width of the dam is increased to accomodate an access ramp and increase <br />the top width to accommodate future dredging operations. The increased <br />width will also ensure amore stable structure. <br />3. The invert is -raised to 6613.8 to fulfill the regulatory requirement of a <br />nonclogging dewatering device no lower than the maximum sediment storage <br />volume. Colowyo has committed to remove sediment at 60% of the predicted <br />3 year sediment level. The 60% removal elevation is 6613.8. <br />4. The principal spillway is raised to 6619 to provide storage for both the <br />10 year 24 hour event and sediment volume at the 60% removal of the 3 <br />year sediment yield. <br />5. A ::ey cut is included. <br />A summary of changes in design <br />of the pond layout is shown in Figure 1, <br />emergency spillway are shoern in Figure 2. <br />is presented in Table 2. A plan view <br />and cross sections of the dam and <br /> <br />