National Dam Safety Program. Loch Haven Lake Dam (Inventory Number VA 16102), Roanoke River Basin, Roanoke County, Virginia. Phase I Inspection Report

摘要

Loch Haven Dam is a concrete structure about 79.5 feet long and 25 feet high. The dam is classified as a small dam with a significant hazard classification. The principal spillway is a 5-inch cast iron pipe that passes through the dam. The secondary spillway is a rectangular cut near the center of the dam. An 8-inch PVC siphon pipe is available for lowering the water level in the reservoir below the principal spillway intake. The reservoir provides recreation for various community civic organizations, local businesses, members of the Loch Haven Country Club, and six families living on the property. Based on criteria established by the Department of the Army, Office of the Chief of Engineers (OCE), the Spillway Design Flood (SDF) is the 100 Year Flood. The secondary spillway will pass 4 percent of the PMF or 17 percent of the SDF without overtopping the crest of the dam. The SDF will overtop the dam by a maximum 3.66 feet, reach an average critical velocity of 9.1 feet per second and flow over the dam for 6.75 hours. The overtopping velocities are not considered detrimental to the dam. The secondary spillway is adjudged inadequate but not seriously inadequate.