The goal of this project was to provide local sponsors and NRCS with data regarding the condition of five dams; identify whether the dams met current State and Federal design, performance, and dam safety standards; risks to the public should the dams fail; and, rehabilitation alternatives for each dam.
Tasks included evaluating the existing condition, verifying the hydrologic parameters used for the original design, developing a breach inundation map, evaluating the current hazard classification, determining if the dams met current design standards, computing the risk index to help identify viable rehabilitation projects, and developing alternative concepts for bringing the dams into compliance with current safety and performance standards.
In the first step, an on-site evaluation of each structure was conducted and a dam inspection checklist was prepared for each dam. Routine inspection documents were also reviewed. Breach inundation analyses were performed to estimate the population at risk (PAR) and compute the risk index to assist in the hazard classification assessment. A hydraulic and hydrologic evaluation of the existing dams was performed using the SITES computer program.
The geological and geotechnical information, including the geological maps and geotechnical boring logs, were reviewed for all five dam sites and head cut erodibility indices were determined. The overall stability of the dams and seepage issues were also evaluated using the available geotechnical information and observations from the site visits.
The results indicated that the dams do not meet current State and Federal dam safety performance standards for auxiliary spillway stability and integrity, as well as for hydraulic capacity. We recommended rehabilitation alternatives and a cost analysis for each proposed alternative was also provided.