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SECTIONTHREE 3.1 PROJECT HISTORY Background I~ormanon Knouth Reservoir is impounded by two earth embankment dams. The northern dam has a structural height of 15 feet and is 900-foot-long. The southern dam has a maximum structural height of 15 feet and is 1,100-foot-long. Historical drawings are presented in Appendix C. There are three historical outlets for the reservoir. The first outlet is operational and is located. along the left abutment of the northern dam. The outlet consists of an 18-inch diameter steel pipe controlled by an initial gate chamber within the embankment. URS performed a video inspection of the outlet and it appeared to be in satisfactory condition. A second non-operational low-level outlet, with an invert elevation lower than the operational outlet, is located along the maximum section of the northern dam. The second outlet consists of a tar enamel lined and coated 18-inch diameter steel pipe. The historical drawings also indicate that the pipe is protected from corrosion with No. 20 magnesium anodes. The outlet has an upstream gate operator which was not inspected during the video inspection. The gate operator was removed in the past and will need to be replaced if the outlet will be used in the future. The drawings also indicate concrete seepage cutoff walis along the pipe. URS performed a video inspection of the second outlet and it appeared to be in satisfactory condition. A third outlet was abandoned in the past and is located along the maximum section of the southern dam. The date and methods of abandonment are not known. The inlet and outlets of the conduit are not visible. The spillway consists of an uncontrolled natural cut located along the right abutment of the southern embankment. The spillway is grassed lined but is not protected from erosion. Historical drawings show the spillway located along the left abutment of the northern dam but the spillway was never constructed. The justification for the spillway location is not known. The natural drainageway is located to the south of the southern embankment. Flood waters should be returned to the natural floodway to avoid floodway right of way issues as required by SEO Rule 5.9.6.1.1. There is also an irrigation ditch that is located along the downstream face of the northern embankinent. The ditch is approximately 2-foot-wide and 3-foot-deep at its ma~cimum section. The ditch diverts water from the Supply Ditch into the reservoir through a headgate located to the west of the reservoir. ~ ~S 3-1