Integrated Geophysical And Remediation Services — Antlers Bridge, CA
Client
- Confidential
Project Value 
N/A
Market
Energy And Environment
Services
Security Operations
We led the unexploded ordnance recovery effort following the partial demolition of the I‑5 Antlers Bridge over Lake Shasta. During demolition, the construction contractor used linear shaped charges to remove the existing structure. However, several charges failed to detonate and dispersed into the lake and nearby terrain. As a result, we stepped in to reduce risk and protect public safety and environmental resources.
Quality Assurance And Recovery Oversight
After the contractor completed initial recovery attempts, we performed comprehensive quality assurance surveys.
Through this effort, we located and recovered an additional 100 unexploded linear shaped charges, significantly reducing the potential risk to both the environment and public safety
Challenging Site Conditions
The recovery operation was complicated by a range of site-specific challenges. These included steep slopes with gradients of 45 degrees or more and a lake depth reaching 100 feet. There was also limited visibility due to murky water. Additionally, seasonal fluctuations in water level could vary by as much as 80 feet. To effectively address these obstacles and ensure thorough coverage, we implemented a multi-faceted detection strategy:
- Diver searches: Skilled divers conducted underwater sweeps in targeted areas, leveraging their expertise to locate and retrieve charges despite difficult underwater conditions.
- Side-scan sonar: Advanced sonar technology was used to image the lakebed and identify potential anomalies consistent with unexploded charges. This enabled precise targeting of recovery efforts.
- Terrestrial digital geophysical mapping (DGM): This technique allowed us to survey adjacent land areas for buried or otherwise concealed charges. Thus, it enhanced the overall thoroughness of our search.
- Explosive-sniffing canines: Specially trained dogs were deployed to detect trace odors of explosives. This provided an additional layer of assurance in both aquatic and terrestrial search zones.
Successful Project Outcome
Upon completion of our QA surveys and the recovery of additional unexploded LSCs, the client proceeded with the bridge replacement project without further incident. The final assessment confirmed that the drinking water reservoir and the surrounding environment were free from any lingering threat posed by the previously undetected charges. This outcome not only ensured the safety of local communities and ecological resources but also demonstrated the effectiveness of our integrated detection and recovery approach in overcoming complex site conditions.
