National Dam Safety Program. Keyes Branch Mine Dam (MO 30386), Mississippi - Kaskaskia - St. Louis Basin, Washington County, Missouri. Phase I Inspection

摘要

Keyes Branch Mine Dam, Identification Number 30386, was inspected. Based on the criteria in the guidelines, the dam is judged to be in the significant hazard classification. The estimated damage zone extends approximately 10 mi downstream. The apparently occupied structures downstream from the dam appear to be above potential flood levels. Damage and loss of life would likely be restricted to traffic on state highways and railroads which cross the creek. The closest state road is approximately 1.6 mi downstream. Keyes Branch Mine Dam is in the intermediate size classification based on its maximum height of 57 ft, and on its maximum reservoir storage volume of 1400 ac-ft. Our inspection and evaluation indicate the dam to be in a fair to good condition. A slump-type landslide on the downstream face of the embankment, where sliding had been described earlier by the Missouri Geological Survey, suggests continuing instability at this location.