ENERGY & SUBSTATIONS · ND
Mandan Substation Foundation Investigation
Substation expansion foundation borings with rock coring to refusal at termination structures.
Client
Regional Utility · Morton County ND
Location
Mandan, ND
Year
2024
Footage
1,800 ft
Borings
8
Challenge
A 230-kV substation expansion adjacent to an energized yard. Eight boring locations: control building, two transformer pads, and five termination structures. Access tight; switching windows limited.
What we did
Single track-mounted rig coordinated with the utility's switching team. SPT and Shelby tube sampling through overburden, NQ wireline coring at termination structures where pile foundations were specified.
OSHA arc-flash protocols on the energized side of the yard. Crew wore the required PPE and worked under utility supervision in the active areas.
Outcome
1,800 feet of footage, 8 borings. Coring data showed competent rock at shallower depth than the original geotech assumption. Termination foundation design adjusted to drilled piers instead of deeper drilled-shaft piles. Estimated $80K saved in over-spec'd footings.
OUTCOME
Termination-structure design adjusted based on coring data, saving roughly $80K in over-spec'd footings.
GALLERY
Field photos.
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