This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).
This report was prepared under the National Program of Inspection of Non-Federal Dams. This report assesses the general condition of the dam with respect to safety, based on available data and on visual inspection, to determine if the dam poses hazards to human life or property. (Author).
The dam is a zoned, rolled, earthfill structure with a straight alignment between rock abutments. The top of dam width is 45 feet and the axis length of the crest of the embankment was measured as 856 feet. The maximum height of the dam was measured as 38 feet above creekbed elevation. The spillway serves as both an emergency spillway for larger flows and a principal spillway for the normal flows. The spillway crest and adjacent channel area were blasted out of rock just to the right of the right abutment. A low level drain consists of two 22 inch diameter welded steel pipes which pass through the embankment side by side. Each pipe is controlled at the downstream end by a 24 inch gate valve. The dam appears to be in satisfactory condition. However, several deficiencies were noted by the inspection team that could affect the safety of the dam. Our inspection and evaluation indicates that the spillway of Incline Village Lake Dam can accommodate approximately 60 percent of the Probable Maximum Flood without overtopping the dam. Our evaluation also indicates that the reservoir/spillway system can accommodate the one-percent chance flood without overtopping.
The purpose of this inspection was to assess the general condition of the dam with respect to safety and, based upon this inspection and available data, determine if the dam poses a hazard to human life or property. According to the criteria set forth in the recommended guidelines, the magnitude of the spillway design flood for the Cedar Knoll Farm Lake Dam, which is classified as small in size and of high hazard potential, is specified to be a minimum of one-half the Probable Maximum Flood (PMF). Results of a hydrologic/hydraulic analysis indicated that the spillways (principal plus emergency) are inadequate to pass lake outflow resulting from a storm of one-half PMF magnitude or the outflow from the one percent (100-year frequency) flood without overtopping the dam. The spillways are capable, however, of passing lake outflow resulting from the ten percent chance (10-year frequency) flood and the outflow corresponding to about 12 percent of the PMF without over-topping the dam. According to the St. Louis District, Corps of Engineers, the length of the downstream damage zone, should failure of the dam occur, is estimated to be five miles. Accordingly, within the possible damage zone are four dwellings, several farm buildings and State Highway F.
The Forest Lake Dam was visually inspected. The purpose of this inspection was to assess the general condition of the dam with respect to safety and, based upon this inspection and available data, determine if the dam poses a hazard to human life or property. The following report summarizes the findings of the visual inspection and the results of certain hydrologic/hydraulic investigations performed under the direction of the inspection team. Based on the visual inspection and the results of these hydrologic/hydraulic investigations, the present general condition of the dam is considered to be less than satisfactory.
Sections 1-2. Keyword Index.--Section 3. Personal author index.--Section 4. Corporate author index.-- Section 5. Contract/grant number index, NTIS order/report number index 1-E.--Section 6. NTIS order/report number index F-Z.
The dam is a compacted earthfill structure between earth abutments. The top width is 35 feet for a distance of 150 feet to the right of the spillway while the remainder of the top of dam has been disguised by the dumping of fill material over the downstream face. The total length of the dam is 410 feet between the right abutment and the spillway. The spillway is an earthcut, uncontrolled, open channel and is cut into the left abutment of the dam. No low level outlets or outlet works were provided for this dam. The inspection and evaluation by the consultant's inspection team indicate that the spillway of Smith Lake Dam does not meet the criteria set forth in the guidelines for a dam having the above size and hazard potential. It was determined that the reservoir/spillway system can accommodate approximately 65 percent of the Probable Maximum Flood without overtopping the dam. The evaluation also indicates that the reservoir/spillway system can accommodate the one-percent chance flood (100-year flood) without overtopping.
