Secant Pile Walls
Secant pile walls create a continuous drilled barrier for deep, constrained, or groundwater-sensitive excavations.
Pacific Foundation can deliver secant walls alongside soil mixing and jet grouting, giving clients one contractor for interconnected excavation-support work.
How Secant Walls Work
Secant walls are formed by drilling overlapping primary and secondary piles along the wall alignment. Selected piles receive reinforcement where the design requires structural capacity.
The system is considered when continuity, stiffness, groundwater, property limits, or permanent-wall requirements make open lagging less practical. Its value depends on controlling layout, drilling tolerance, concrete placement, and the sequence for support and excavation.
When to Use Secant Walls
Secant pile walls fit excavations that need a continuous drilled wall before the site is opened. They are often considered where groundwater, retained height, nearby structures, or limited room make open lagging less practical.
Where groundwater is manageable and movement limits allow staged lagging, a soldier pile wall may be more efficient.
Groundwater-Sensitive Excavations
Used when groundwater movement, seepage, or dewatering assumptions affect wall selection and excavation risk.
Tight Property Lines
Useful where the wall must support excavation close to existing structures, utilities, roads, or site boundaries.
Deep Or Stiff Wall Requirements
A better fit when retained height, surcharge, movement tolerance, or permanent wall use requires more continuity.
Utility And Infrastructure Structures
Commonly reviewed for pump stations, vaults, below-grade structures, and constrained public-infrastructure excavations.
Equipment and Tooling
Secant pile wall equipment is selected around the wall, not the other way around. Pile diameter, wall depth, overlap requirements, casing needs, reinforcement, access, overhead clearance, ground conditions, and groundwater all affect the installation approach.
The equipment plan should also account for support operations. Spoil handling, reinforcement staging, concrete supply, casing movement, survey control, and access for excavation can affect production as much as the drilling itself.
Drilling method and casing approach depend on wall depth, ground conditions, groundwater, obstruction risk, and required overlap control.
Request Scope ReviewWall alignment, pile spacing, survey control, and guide setup help keep the secant sequence tied to the excavation-support design.
Request Scope ReviewReinforcement installation and concrete placement must be coordinated with pile sequence, cage geometry, access, and inspection requirements.
Request Scope ReviewEquipment selection depends on wall depth, ground conditions, groundwater, access, pile geometry, and installation tolerances.
Project Experience
These projects show how wall continuity, groundwater, access, and adjacent structures shape the secant pile plan.
Lake Oswego, OR / Water & Wastewater Lake Oswego River Intake Pump Station
Pacific Foundation supported the project with secant piles.
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Honolulu, HI / Commercial HKV Ka Haku Tower
Pacific Foundation supported Hilton Kings Village / Ka Haku Tower with design-build CDSM, jet-grout bottom-seal work, a design-build secant pile wall, and a 120-foot CFA test pile with O-Cell testing.
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Honolulu, HI / Commercial Ward Village Block O Kilohana
Pacific Foundation's scope included secant piles.
View projectPacific can review the excavation requirements and determine whether secant piles fit the proposed shoring system.
Pacific Capabilities
Pacific reviews the design, groundwater, utilities, casing needs, access, spoils, reinforcement, and excavation sequence before drilling starts. That planning helps contractors compare secant walls with other retention methods on constructability, not terminology.
Secant Wall FAQs
When are secant pile walls preferred?
Secant pile walls are often preferred when excavation support needs a continuous drilled wall. They are commonly reviewed for deeper excavations, groundwater-sensitive work, tight property lines, adjacent structures, utility structures, and permanent or dual-purpose wall conditions.
How are secant pile walls different from soldier pile walls?
Soldier pile walls use spaced piles with lagging installed between them as excavation advances. Secant pile walls use overlapping drilled piles to create a more continuous wall before excavation begins. The choice depends on groundwater, wall stiffness, access, wall geometry, and performance requirements.
Are secant pile walls waterproof?
Secant pile walls can help reduce groundwater movement through the wall line, but they should not be described as automatically waterproof. Groundwater performance depends on design, overlap, verticality, construction tolerance, joints, soil conditions, and any supplemental groundwater-control measures.
What makes secant pile walls more involved to build?
The main challenges are layout control, verticality, pile overlap, sequencing, casing, reinforcement placement, concrete placement, obstructions, groundwater, and access. Those controls matter because the wall must perform as a system when excavation exposes it.
Can secant pile walls be permanent?
Yes. Secant pile walls can be designed as temporary excavation support, permanent retaining walls, or dual-purpose systems. Permanent use depends on the project design, reinforcement, drainage, corrosion protection, finish requirements, and how the wall connects to the final structure.
What should we send Pacific for review?
Send excavation-support plans, geotechnical report, groundwater information, wall alignment, retained heights, utility information, property-line constraints, adjacent-structure information, reinforcement details, specifications, and schedule or phasing requirements.
Discuss Your Secant Wall Scope
Send the shoring plans, geotechnical report, groundwater information, wall geometry, retained heights, utility constraints, adjacent structures, and schedule. Pacific will review whether secant piles fit the excavation.