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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).
Gudaitis Lake Dam is in the small size classification based on its maximum height of 25 ft and on its reservoir storage volume of about 180 ac-ft. The small dam classification includes dams between 25 and 40 ft in height or having storage capacities between 50 and 1000 ac-ft. The inspection and evaluation indicate the dam is in fair condition. This evaluation is primarily based on hydrologic analyses that indicate that a flood greater than 12 percent of the PMF will effectively overtop the dam. The dam will also be effectively overtopped by the one percent probability-of-occurrence (100 year) flood event. A 40 ft wide zone of slow seepage was noted at the toe of the dam, but the seepage water was not transporting any soil particles at the time of our inspection. The downstream face of the dam is heavily vegetated with relatively young trees up to 12 in. in diameter. This vegetation obscured portions of the dam from inspection. The spillway discharge channel is narrow and shallow and is bordered by many large trees. Deep gulley erosion is occurring where this channel traverses steeper slopes. Flood flows in this channel could cause overtopping of the channel and erosion of the channel walls, resulting in possible erosion at the toe of the dam.
The Loch Leonard Dam is an earthfill structure approximately 19 ft. high and 1900 ft. long at the crest. The appurtenant works consist of: a pump station with an 8-inch discharge pipe from the lake to a Missouri Public Service Co. power plant; a pump station in the stream by the lake with one 18 inch diameter pipe to the settling basin; a 15 inch diameter CMP from the settling basin to the stream; and a 60 inch diameter pipe between the lake and settling basin. Our inspection and evaluation indicates that the combined spillways do not meet the criteria set forth in the guidelines fro a dam having the above size and hazard potential. The combined spillways will pass 9 percent of the Probable Maximum Flood without overtopping. Deficiencies visually observed by the inspection team were: (1) Some brush and small trees on both faces of the dam; (2) Seepage area the downstream toe across from Sta. 2 + 50; (3) Seepage through the embankment across from the pump station at Sta. 11 + 30; and (4) Inlet to 15 inch primary spillway pipe out of the settling basin is blocked with vegetation and debris.
The purpose of this inspection of Six Mile Lane Lake Dam was to make an assessment of the general conditions of the dam with respect to safety, based upon available data and visual inspection, in order to determine if the dam poses hazards to human life or property. The inspection and evaluation indicates that the spillways meet the criteria set forth in the recommended guidelines for a small dam having a high hazard potential. One-half of the Probable Maximum Flood is the appropriate spillway design flood. The spillways will pass the 100-year flood (a flood having a one percent probability of being exceeded in any year) without overtopping the dam. The spillways will pass 75% of the Probable Maximum Flood without overtopping the dam. Maintenance procedures are recommended.