- Geotechnical investigations
- Alternatives evaluation
- Hydrology Report
- Dam breach analyses
- Hazard classification
- Emergency Action Plan
- New embankment design
- Spillway design
- Outlet works design
- Environmental permitting support
- Bidding services
- Resident engineering
- Construction administration services
The original Walsenburg City Lake Dam was a 22-foot-high, 3,000-foot-long, high-hazard dam constructed circa 1910. Major dam safety issues included seepage, slope stability, lack of erosion control protection on the upstream slope and dam crest, and an inadequate outlet works and spillway. City of Walsenburg (City) budget constraints required the design work to be performed in several phases.
For the planning phase of the project, RJH prepared a Hydrology Report, Dam Breach Mapping Report, Hazard Classification Report, and a revised Emergency Action Plan. RJH also identified and evaluated three alternatives for embankment rehabilitation, two alternatives for the service spillway rehabilitation, and three alternatives for the auxiliary spillway rehabilitation to address the dam safety issues.
After the planning phase, the City identified a need to increase the lake storage by at least 120 acre-feet. The City selected the following alternative to be advanced to final design:
- Removal and replacement of the current embankment with the addition of increasing the embankment height by 3 feet.
- Stand-alone auxiliary spillway with a concrete control structure and grouted riprap discharge channel.
- Outlet works with a control tower, low-level intake, and service spillway.
RJH led the work from initial evaluation and assessment of the existing dam through identification of dam safety issues, alternatives development, state permitting, final design, and construction engineering. RJH also assisted the City in obtaining a loan from the Colorado Water Conservation Board.