- Litigation support
- Geotechnical investigations
- Alternatives evaluation
- Hydrology Report
- Dam breach analyses
- Hazard classification
- Risk assessments
- New embankment design
- Spillway design
- Outlet works design
- Bidding services
- Resident engineering
- Construction administration services
The Ten Mile Creek Water Preserve Area was a joint project implemented by the U.S. Army Corps of Engineers and the South Florida Water Management District. The intent of the project was to provide seasonal storage of peak stormwater flows and then slowly release flows back to the creek to moderate salinity levels and reduce sediment loads.
The project included a 6,000-acre-foot reservoir created by constructing a 5-mile-long, 20-foot-high earthen embankment. The project was designed by other consultants and constructed several years after design. During first filling, seepage boils appeared when the reservoir reached about 8 feet deep. Based on the observed boils and seepage, the embankment was considered unsafe for water storage, the reservoir was evacuated, and the project could not be used as originally intended.
The U.S. Department of Justice sought out and retained RJH to provide litigation support that included an independent evaluation of the design, assessment if the project was safe to operate, and development of a rehabilitation design to create a functional reservoir.
RJH performed a thorough review of the existing design documents and data, implemented a geotechnical exploration program, and performed extensive modeling to assess dam safety and develop a rehabilitation design. RJH also planned and executed a carefully-controlled full-scale test filling of the reservoir to confirm and calibrate seepage analyses. This included 24-hour monitoring by a team of ten RJH field engineers over a several week period.
The dam and levee safety issues that RJH identified as needing remediation included unstable slopes, significant seepage instability of the foundation (i.e., high probability of a backward erosion piping failure in the foundation), instability of the upstream (waterside) slope due to rapid drawdown, and wave-erosion of the upstream (waterside) slope.