NRCS Increases Safety with Dam Rehabilitation Project

Boiling Springs 1 is an existing dam structure that was constructed in 1973 in Latimer County, Oklahoma. It has operated for 45 of its 50-year design life. This site was originally designed as a low hazard structure. However, it has since been re-classified as a high hazard due to downstream development.

To increase safety for the area, the Natural Resource Conservation Service (NRCS) knew they needed to design a new solution that could perform as needed. They selected Affinis, as part of the Ad Astra team, for the Boiling Springs Dam Rehabilitation project. Together, Ad Astra will provide a design meeting current dam safety criteria and performance standards for a high hazard class structure. The design life will be extended to 100 years from the completion of construction.

Our team started by gathering information about the site. We conducted a site visit, reviewed the hydraulic and hydrologic reports, performed an early alternatives evaluation, and worked with a partner to collect geologic and soil mechanics data for the area. Each of these items was used to inform the design.

Based on our findings, we chose to install a new, roller compacted spillway that is 216 feet wide. We also recommended the inclusion of a new principal spillway inlet tower. Together, these will provide more hydraulic capacity to meet the NRCS and State of Oklahoma dam safety requirements.

There were a number of challenges associated with this design. The first was finding the right size wall configurations for the spillway walls. The next was getting the spillway to fit in the limited area selected for it. The final hurdle was working within the existing dam’s site constraints, while still making sure this approach would work. To prove the effectiveness, NRCS performed a physical model of the spillway to verify the hydraulic modeling results.

The existing top of dam also is a rural road for property owners in the area. The new roller compacted spillway would either require a bridge to maintain the current traffic or a bypass around the dam. Due to right-of-way constraints and terrain, a bridge was determined more feasible. Therefore, NRCS decided to construct a 14-cell box bridge to span the new spillway.

The design for the Boiling Springs Dam Rehabilitation project was completed in July 2022. This project is now ready to bid.