Case Study
Sonic Drilling Reaches 900 ft With Less Than 1% Deviation
At Bingham Canyon Mine, Boart Longyear used sonic drilling to reach a record 900 ft through unconsolidated waste rock while maintaining 100% in-situ samples and less than 1% deviation.
Executive snapshot
- Client
- Kennecott Copper Mine
- Service Used
- Sonic Drilling
- Operating Environment
- Waste rock dump
- Project Outcome
- 900 ft sonic record
Project Requirements
What the project required
Project Conditions
Drill through an unconsolidated waste rock dump containing large blast fragments and unknown total depth.
Technical Requirement
Provide continuous samples, confirm bedrock depth, install monitoring instruments and collect geotechnical samples at defined intervals.
Operational Requirement
Advance in stages with changing bore and casing sizes, then continue beyond the planned 700 ft depth when bedrock had not been reached.
Operational Challenge
What made the project challenging
The program required continuous, representative sampling through highly variable waste material while the true depth of the dump remained unknown.
Project Condition
The waste dump contained unconsolidated material and 10–12 in blast rock fragments.
Technical Constraint
The client needed continuous samples plus piezometers, lysimeters and scheduled geotechnical samples.
Operational Pressure
The team had to adjust bore and casing sizes in stages and safely continue deeper than the original target.
Boart Longyear Approach
How Boart Longyear approached the work
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Experienced Crews
Sonic crews advanced through unconsolidated waste rock containing 10- to 12-inch blast fragments while producing continuous, representative samples.
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Method And Equipment Planning
The hole advanced in stages: 9 inches to 350 ft, 8 inches to 500 ft, 7 inches to 750 ft, 6 inches to 867 ft, and a final 4-inch borehole to 900 ft.
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Equipment And Tooling
Split-spoon samples were collected every 20 ft through the first 200 ft; casing, piezometers and lysimeters were incorporated as the program advanced.
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Safety Systems And Field Controls
The team advanced in controlled stages and reassessed the rig’s capability and pullback before continuing beyond the planned depth.
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Site Planning
Sampling intervals, monitoring-instrument installation and staged casing changes were coordinated around the 700 ft target and uncertain bedrock depth.
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Technical Supervision
Bedrock status and rig capacity were evaluated as the hole deepened, while final performance confirmed 100% in-situ samples and less than 1% deviation.
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Regional And Field Support
Field support adapted tooling and casing from the initial 9-inch borehole through the final uncased 4-inch push.
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Execution Discipline
The record depth was completed in 16 12-hour shifts, including two shifts lost to rain, using a deliberate staged approach.
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Quality / Project Outcome
The hole reached a record 900 ft through dry drilling, delivered 100% in-situ core samples and maintained less than 1% deviation.
Outcome / Proof
What the work delivered
900 ft Sonic Record
Boart Longyear reached 274.32 m (900 ft), setting a new sonic drilling depth record.
28% Beyond Target Depth
The final depth exceeded the original 700 ft goal by more than 28%.
100% Samples / <1% Deviation
The full dry-drilled depth produced 100% in-situ core samples with less than 1% hole deviation.
Why It Mattered
Impact
The program extended beyond target depth without sacrificing sample quality or borehole control, giving the client a clearer picture of the waste dump.
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