· Dam Built in 1960
· 9 Control Gates
· 16 Foot Head
· 781 Feet Overall Structural
· High Flow Velocity/Low Visibility
AMI Consulting Engineers, PA provided Stanley Consultants sector scan imaging inspections of the Ottumwa Dam. The intent of each project was to complete imaging and dive investigations to identify current conditions and as built construction of the underwater structures on the dam.
The initial imaging and dive inspections in 2011 were completed as a baseline inspection and to determine if apron failure and scour had occurred. Due to the high flows and low visibility of this river, AMI had to work with dam operations to cycle gates to minimize the effects of the high flow and produce the best quality images possible. During the imaging of the dam, AMI discovered additional foundations possibly constructed during the original dam construction. It was later discovered that after these foundations and aprons were built, the dam was built just upstream due to better rock conditions than the original location. Rock in this area is soft and scour was a concern under the aprons.
AMI was able to confirm the loss of stone due to major flooding in past years on the river, with almost all of the downstream scour stone protection carried away by flood waters. Final scanning of all dam elements in plan and profile were completed and combined in a complete mosaic.