Rimrock Rockfall Evaluation, MT
Ninyo & Moore, a SOCOTEC Company, provided geotechnical services during the forensic evaluation of a major rockfall that severely damaged a residence in Billings, Montana.
Key Information
Project Name: Rimrock Rockfall Evaluation
Client: Confidential
Location: Billings, Montana
Services Provided: Geotechnical Engineering, Forensic Evaluation
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The Challenge
Evaluating the Cause of a Major Rockfall
In 2019, a major rockfall released from the prominent sandstone cliff face known as the Rimrocks, located on the slope above the property to the north. Extending several miles east–west, the Rimrocks form the primary landform in northern Billings. From the base of the cliff, a boulder-covered slope descends approximately 130 feet to the street in front of the damaged residence.
The event took place at approximately 1:30 a.m., while the resident was asleep in the rear of the home, increasing the urgency of access, safety measures, and site evaluation.
The Solution
Forensic Rockfall Evaluation & Geotechnical Reporting
Ninyo & Moore, a SOCOTEC Company, was engaged to perform a technical evaluation of the rockfall event. We mobilized a geotechnical team to evaluate the cause of the rockfall, conduct site observations, compile data, and develop forensic conclusions. Despite the absence of a local Montana office, the team performed Catastrophic evaluation (CAT) and prepared a geotechnical report addressing the event sequence and contributing factors.
Scope of Services (as applicable):
Geotechnical site reconnaissance and documentation
Forensic evaluation of source area and runout conditions
Data compilation and interpretation
Preparation of findings and causation conclusions in a formal report
Ninyo & Moore, a SOCOTEC Company, was engaged to perform a technical evaluation of the rockfall event. We mobilized a geotechnical team to evaluate the cause of the rockfall, conduct site observations, compile data, and develop forensic conclusions. Despite the absence of a local Montana office, the team performed Catastrophic evaluation (CAT) and prepared a geotechnical report addressing the event sequence and contributing factors.
Scope of Services (as applicable):
Geotechnical site reconnaissance and documentation
Forensic evaluation of source area and runout conditions
Data compilation and interpretation
Preparation of findings and causation conclusions in a formal report
The Results
Documented Causation & Owner Support
The evaluation delivered a clear, documented understanding of rockfall causation, supporting the client with formal geotechnical findings. The work demonstrated Ninyo & Moore’s ability to rapidly mobilize trained staff for CAT and deliver forensic reporting to inform next steps.
Key Outcomes:
Determined source and contributing factors for the rockfall event
Provided an authoritative geotechnical report of findings and conclusions
Enabled stakeholders to plan informed follow‑up actions for safety and remediation
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