Laserfiche WebLink
<br />Works of Improvement <br /> <br />Figures I and 2 show plans for floodwater <br />structure is typical of the 10 floodwater <br />3 through 7 show profiles of the proposed <br />flood plain damage in vicinity of Ovid. <br />locations and benefited areas. <br /> <br />retarding structure SS-3. This <br />retarding structures. Figures <br />floodways. Figure 8 shows <br />The proJect map shows structure <br /> <br />There are no displaced persons nor relocation assistance Involved in the <br />structural program. <br /> <br />The selected structural measures as designed will not adversely effect <br />any rare or endangered species thought to frequent the watershed. <br /> <br />There are no known archeological or historical sites in the proposed <br />construction areas. If evidence is found or presented during construc- <br />tion that any materials exist or may be present, construction will stop <br />until the appl icable provisions of P.l. 93-291 and/or P.L. 89-665 have <br />been complied with. Applicable state laws concerning archeological and <br />historical site preservation will also be complied with. <br /> <br />Floodwater Retarding Structures <br /> <br />Floodwater retarding structures with the required floodwater and sediment <br />volumes are designed to control approximately 56 percent of the watershed <br />area. <br /> <br />Classification, Storage, and level of Control <br /> <br />The,floodwater retarding structures are class a with floodwater storage <br />for the 50-year' freque'ncy storm runoff and have sediment storage for the <br />anticipated lOO-year accumulation. A two-stage principal spillway in <br />each dam will provide control of the 37-1/2 year storm through the low <br />stage, and the 50-year frequency storm through the high stage. Total <br />storage of the floodwater retarding structures is 5,731 acre-feet of <br />which 3,961 is for floodwater, and 1,770 is for sediment storage. The <br />structures have no permanent conservation storage. A drawdown tube is <br />provided to drain the sediment pools. No incidental recreation use is <br />foreseen at any of the structure sites. <br /> <br />Site Geology <br /> <br />Bedrock underlying all of the sites consists of light brown claystone <br />and siltstone of the Brule formation of Oligocene Age. These materials <br />are firm and relatively impermeable. The bedrock in the valley bottoms <br />at most of the sites is overlain by alluvial deposits generally consis- <br />ting of silt and clay in the lower part and silty well-graded sandin <br /> <br />36 <br />