The Ohio Department of Natural Resources (ODNR) owns and manages more than 800,000 acres of land and has jurisdiction over more than 120,000 acres of inland waters and 2.25 million acres of Lake Erie. Schnabel has provided dam safety support to ODNR, the owner and regulator of dams. This included evaluations of Lake Milton, Hargus Lake, and Lake Logan dams to bring them into compliance with dam safety regulations.

As an initial step toward prioritizing expenditures, we proposed and completed a risk assessment that included a team consisting of a facilitator and subject matter experts in geotechnical, hydrologic, hydraulic, and structural engineering for dams. The team used recently completed engineering assessments by others to obtain data on spillway capacity, embankment stability, and outlet works deficiencies at each dam. During the process, which included site visits and workshops with park staff and ODNR engineering and dam safety representatives, the team identified potential failure modes and developed semi-quantitative risk estimates (likelihood and consequences). The risk assessment resulted in recommendations for additional geotechnical explorations and engineering analyses to further understand the dam safety risks at each dam.

We developed and implemented a comprehensive data collection program involving geotechnical explorations, targeted geophysical surveys, and high-resolution multi-beam bathymetry to address identified gaps. Supplementary analyses supported the independent assessments for each dam, resulting in three prioritized and specific rehabilitation programs. We are currently participating in the design for dam safety modifications to address the highest priority failure modes at both Hargus Dam and Lake Milton Dam.