Geopier ImpactTM


The Geopier Impact System is an efficient and cost-effective intermediate foundation solution for the support of settlement-sensitive structures. The Impact System, like the Geopier GP3TM System, creates stiff Rammed Aggregate Pier® elements using a patented vertical ramming process. The Geopier Impact System is extremely cost effective for installations in soils subject to caving because construction is facilitated using a patented displacement mandrel. It can replace massive overexcavation and replacement, deep foundations, including driven piles, drilled shafts or augered cast-in-place piles. This high-performing system provides unsurpassed strength, stiffness and superior levels of performance.


The Geopier Impact Construction Process

  1. Impact System support for St. Cloud Live! 300 Mixed Use Building, St. Cloud, MNA specially designed mandrel and tamper foot is driven into the ground using a strong static force augmented by dynamic vertical impact energy. Depths normally range from about 10 to 40 feet, depending on design requirements. A sacrificial cap or other flow restrictors prevent soil from entering the tamper foot and mandrel during driving. The process eliminates spoils and displaces soils laterally, densifying and reinforcing the existing soils.
  2. After driving to design depth, the hollow mandrel serves as a conduit for aggregate placement. Aggregate is placed inside the mandrel. The mandrel is then lifted approximately three feet and then driven back down two feet, forming a one-foot thick compacted lift. Compaction is achieved through static down force and dynamic vertical ramming from the hammer. The process densifies aggregate vertically and the patented beveled tamper foot forces aggregate laterally into cavity sidewalls. This results in soil improvement, excellent coupling with surrounding soils and reliable settlement control with superior strength and stiffness.
  3. Following installation, the Rammed Aggregate Pier (RAP) elements support shallow foundations, floor slabs and reduce liquefaction potential and improve stability support of embankments, walls and tank pads. The footing stresses are attracted to the stiff RAP elements, resulting in engineered settlement control.

Construction Advantages of the Geopier Impact System

  • Features clean and rapid installation process
  • Eliminates casing and allows for construction in caving soils and high ground water table sand
  • Densifies granular soils and reinforces cohesive soils
  • Dry process results in little construction mess or siltation concerns
  • Offers a sustainable solution and LEED® point enhancement
  • Environmentally safe with no spoils to remove or treat
  • Prevents contamination migration and improves capacity by adding cementitious mixes to improve stiffness and bearing support
  • Accelerates construction schedules
  • Allows deep treatment for liquefaction
  • Features low vibration levels when compared to piles
  • Reliable and cost effective

Impact System support for Grain Storage Bin, North Country Coop, Adams, MN

Design/Performance Advantages of Geopier Impact System

  • Stronger and stiffer elements
  • Excellent settlement control
  • Superior support capacity
  • Bearing pressure increases up to 10,000 psf
  • Offers structural support of buildings
  • Often results in a 20% to 50% savings
  • Engineered for specific soil conditions and loads

Applications for Impact System

  • Foundations 
  • Floor Slabs
  • Liquefaction/Seismic
  • Biofuel Facilities
  • Industrial Tanks
  • Wind Turbines
  • Transportation
  • MSE Walls
  • Embankments
  • Railroad
  • Uplift and Lateral Load Resistance
  • Slope Stabilization