- 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
Antero Dam was completed in 1909 with a hydraulic fill core and shells constructed with horse drawn carts. The dam was originally designed for 68,000 acre-feet of storage, but the capacity had been restricted by the Colorado Office of the State Engineer to 20 percent of the total capacity because of numerous, significant dam safety concerns.
The dam is located at an elevation of about 9,000 feet, and the construction season is relatively short.
For the planning phase of the project, RJH performed geotechnical, geologic, and inflow hydrology evaluations and worked with risk estimators to perform a Potential Failure Modes Analysis and Quantitative Risk Assessment to evaluate the risk of various failure modes. Based on this work, RJH evaluated five alternatives to rehabilitate the dam.
The rehabilitation was designed and constructed in three phases to accommodate the relatively short construction seasons. RJH provided design and construction management for each phase.
- Phase I included a downstream filter sand trench using an innovative bio-polymer slurry trench method.
- Phase II included flattening the downstream embankment slope and installing a toe drain.
- Phase III included installing a soil-bentonite barrier wall, additional embankment flattening, and upstream erosion protection.
These embankment modifications, along with outlet works and spillway modifications by others, have allowed the storage restrictions on the reservoir to be removed.