Biogen Soil Nail Walls

Soil Nail Walls

Soil nail walls are constructed by drilling soil nails on a close pattern and applying 4 to 6 inches of shotcrete facing in lifts.  Soil nail walls provide an economical means to retain soils in a “top-down” construction method.

Driven Soil Nail vs. Drilled Soil Nail comparison sheet (PDF)

  • Temporary excavation shoring
  • Permanent site retaining walls
  • Slope stabilization
  • Excavate 5 feet
  • Drill 4 to 6 inch diameter holes and grout in-place an all thread bar
  • Place reinforcement and shotcrete face
  • Proof test 5% soil nails
  • Repeat process to bottom of excavation

When we need a soil nail wall sub again, I highly recommend Subsurface.  They worked with our ever changing schedule without complaining.

Eric Perkinson, Brasfield & Gorrie

Duke University Bed Tower Addition Wall Face

Anchored Soldier Pile Walls

Anchored soldier pile walls are offered as a solution when the site requires a stiff excavation shoring system, especially with multiple utility conflicts.

  • Temporary excavation shoring
  • Permanent site retaining walls
  • Slope stabilization
  • Install driven or drilled and placed piles
  • Excavate 5 feet
  • Wood or shotcrete lag between piles
  • Place, test and lock anchors at design elevations
  • Repeat process to bottom of excavation
  • Coating of piles
  • Polyethylene sheathing of strand anchors

The Subsurface Construction team exceeded our expectations in every phase of the project. When challenges presented themselves, the field and office teams were proactive in overcoming them and stayed on schedule. From the bottom to the top, they are driven...

Andrew Hagood, Balfour Beatty



With our significant experience installing micropiles, we offer speed and versatility with small diameter, high capacity deep foundations.

  • Temporary and Permanent Building Underpinning
  • Seismic retrofits
  • Deep foundations in difficult drilling conditions
  • Arresting settlement
  • Bridge Endbents
  • Low overhead installation – under 8’-6”
  • Install casing through overburden to rock, if required
  • Drill socket into rock
  • Trimmie grout reinforcing steel
  • Capacity developed through friction capacity
  • Thread Bar Reinforcing 20 – 150 T

6” to 8” Drilled Hole

  • Pipe Reinforcing 50 to 300 T

8” to 12” Drilled Hole

  • Capacities depend on the quality of the rock

Due to the location of the project, North Carolina State University, I was very impressed at the crew’s manners and respect for their surroundings. They acted very professionally.

Charlie McIntosh, Environment Quality Resources

Driven Soil Nail Walls

Driven Soil Nail Walls

The Driven Soil Nail shoring system consists of driven steel bars with a composite geotextile fabric and wire mesh face, improving installation time by 50% over conventional shoring methods.

Driven Soil Nail vs Drilled Soil Nail Comparison Sheet

  • Temporary excavation shoring
  • Slope stabilization
  • Excavate 5 feet
  • Place geocomposite wall face
  • Drive steel bars
  • Proof test driven nails
  • Repeat process to bottom of excavation

We wish all subcontractors were as professional and cooperative as your team.

Dwayne Rakestraw, New Atlantic Contracting

Aggregate Piers

Aggregate Piers

When a structure is to be built on soils not suitable for shallow foundations, aggregate piers are often an economical alternative to other options such as undercut and replace or a deep foundation system.

  • Reduces settlement and increases the bearing capacity of in-situ soils
  • Reduces cost and time uncertainties during the pre-construction phase associated with undercut and replace
  • Simplifies foundation concrete work by using shallow foundations rather than pile caps
  • Sites containing deep undocumented fill
  • Sites with deep compressible soft soils
  • Heavy building loads that require excessively large footings if supported by in-situ soils
  • There are 2 methods of aggregate pier construction:
    • Top Feed – Soil conditions conducive to open hole drilling methods
    • Bottom Feed – Soil conditions where the soil is not expected to stand up for a suitable period of time
  • Top Feed Installation Process:
    • Pre-drill the aggregate pier location the full design depth
    • Lower the Vibroflot to the bottom of the pre-drilled hole
    • Dump stone from the top into the hole
    • Build the aggregate pier in successive lifts up to the ground surface
  • Bottom Feed Installation Process:
    • Advance the Vibroflot into the ground to the design aggregate pier depth
    • Pour stone into a hopper mounted at the top of the Vibroflot
    • The stone from the hopper travels down a tube that discharges at the tip of the Vibroflot
    • Build the aggregate pier in successive lifts up to the ground surface

Competent staff, proper equipment, and good work ethic.  Professional attitude all around.  

Eddie Self, Taylor and Murphy

micropile underpinning and soil nail shoring


Using micropile underpinning in conjunction with soil nail shoring, we can support existing structures adjacent to deep excavations while maintaining the integrity of the buildings.

  • Temporary and Permanent Building Underpinning
  • Allows for basement construction adjacent to an existing building
  • Support building by underpinning existing footings with micropiles
  • Install a shoring system, typically soil nailing, to retain soil

Subsurface did a great job upfront making sure that we were installing the most effective solutions for our project. And despite a challenging schedule and unexpected underground conditions, the job was still completed ahead of schedule.

Greg Shenkler, Skanska USA Building