Geopier GP3® System

The Geopier GP3® system uses replacement Rammed Aggregate Pier® (RAP) elements to reinforce good to poor soils, including soft to stiff clay and silt, loose to dense sand, organic silt and peat and variable, uncontrolled fill.

The unique installation process utilizes pre-augering and vertical impact ramming energy to construct RAP elements. RAP solutions are designed to provide total and differential settlement control and increased bearing support to meet your project requirements.

Geopier GP3 Design/Construction Process

The process first involves drilling a cavity. Drill depths normally range from about 7 to 30 feet, depending on design requirements. Pre-drilling allows you to see the soil between the borings, so that the piers are engineered to reinforce the right soils.

Layers of aggregate are then introduced into the drilled cavity in thin lifts of one-foot compacted thickness. A patented beveled tamper rams each layer of aggregate using vertical impact ramming energy, resulting in strength and stiffness. The tamper densifies aggregate vertically and forces aggregate laterally into cavity sidewalls. This results in excellent coupling with surrounding soils and reliable settlement control.

Following installation, RAP elements can reinforce embankments and offer slope reinforcement, support shallow foundations, floor slabs and tank pads. The footing stresses are attracted to the stiff RAPs, resulting in engineered settlement control.

Geopier GP3 Construction Advantages

  • Better quality control through visual inspection of drill spoils and modulus tests with telltales
  • Environmentally safe and sustainable offering LEED® point enhancement
  • Clean and rapid installation process
  • Accelerated schedule
  • Versatile system allows for use in sider range of structures
  • Reliable and cost-effective

Geopier GP3 Design/Performance Advantages

  • Stronger and stiffer elements
  • Excellent settlement control
  • Superior support capacity
  • Increased bearing pressure up to 10,000 psf
  • Designed for structural support of buildings
  • Often results in 20% to 50% savings
  • Engineered to meet specific soil conditions and loads
  • Wind and seismic uplift resistance
  • More than 25 years of proven foundation support

RAP Applications

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

CASE HISTORY: Echo Lighting Warehouse – Council Bluffs, IA

Echo Lighting Warehouse

Project Description:

This is a new electrical supply office/warehouse building with a footprint of 117,000 square feet. Compressive column loads of 80 to 460 kips and individual column uplift loads of over 100 kips.

Subsurface Conditions:

The subsurface conditions consist of uncontrolled clay fill underlain by native clay, silt and silty sand. Groundwater was encountered approximately 10 feet below the floor elevation.


The Geopier GP3® system was selected to support foundations that had both compression and uplift loads. A total of 418 Rammed Aggregate Pier® elements were installed in less than two weeks on site. The uplift resistance Geopeir elements had a working tension capacity of 30 kips each. The modulus load test had less than 1/4-inch deflection at a design top-of-pier stress of nearly 17,000 psf.

Project Team

Geopier Designer: Ground Improvement Engineering
Structural Engineer: HGM Associates, Inc. – Council Bluffs, IA
Geotechnical Engineer: Terracon, Inc. – Omaha, Nebraska
General Contractor: Anderson Construction, Council Bluffs, IA
Geopier Installer: Peterson Contractors, Inc., Reinbeck, IA

CASE HISTORY - Mitchell Interchange MSE Walls and Embankments, Milwaukee, WI

Project Description:

This major project included a widening and realignment of Interstate 94 in Milwaukee County, Wisconsin. We presented a value-engineering alternative to limit the use of expensive lightweight fill.


The typical conditions were ten to 20 feet of mixed sand and clay fill that contained organics and rubble, followed by stiff native clay.  In some wall sections up to 24 feet of Weight of Hammer peat and organic clay were encountered during construction.  We were able to adjust the design to accommodate the very poor organic soil conditions.


We worked with Walsh Construction and Milwaukee Transportation Partners to design  ground improvement solutions to limit the use of expensive lightweight fill.  We used the Geopier GP3TM system which enabled the installer, Foundation Service Corporation, to identify changes in soil conditions by visual confirmation of the drill spoils.

The Geopier GP3 system provided cost savings over lightweight fill and enabled Walsh Construction to expedite the wall erection schedule.  Foundation Service Corporation installed 1,520 GP3 elements in 38 days, which included the time to adjust to the unanticipated deep organic soils.

Project Team

Ground Improvement Designer: Ground Improvement Engineering
Structural Engineer: Milwaukee Transportation Partners
Geotechnical Engineer:  Milwaukee Transportation Partners
General Contractor/Developer: Walsh Construction
Geopier GP3 Installer: Foundation Service Corporation, Hudson, Iowa

CASE HISTORY: 69th Street Overpass, Sioux Falls, SD

Project Description:

This major transportation project in Sioux Falls, SD consisted of converting a rural gravel road into an urban four-lane divided section with a new bridge constructed over the BNSF Railroad.  Earthen embankments of up to 40 feet high were needed for the new bridge approaches and MSE retaining walls were constructed for the bridge abutments and grade separation due to restricted right-of-way.  A protected wetland is located immediately north of the roadway.

Subsurface Conditions:

The geotechnical soil borings encountered 4 to 8 feet of clay fill and organic topsoil overlying soft to very stiff clay glacial till.  The exploration found soft to firm alluvial clay above the glacial till at some locations.  Groundwater was measured at depths varying from 2 ½ feet to 6 feet below existing ground surface.


We worked with the design team to determine that the replacement Geopier GP3TM System would be an effective ground improvement solution to increase the bearing capacity, increase the factor of safety for global stability, and provide settlement control for the MSE walls and earthen embankments.

Geopier GP3 installation

The Geopier GP3 system provided significant cost savings over the more expensive over-excavation/refill option, and avoided major impacts to the adjacent protected wetland.  The Geopier approach also allowed the general contractor to build the project in a shorter time schedule during a stretch of wet weather.

Project Team

Owner:  City of Sioux Falls
Geotechnical Engineer:  GeoTek Engineering & Testing Services, Inc.; Sioux Falls, SD
Civil Engineer:  HR Green, Inc.; Sioux Falls, SD
General Contractor: Grangaard Construction, Inc.; Watertown, SD
Construction Administrator:  Sayre Associates; Sioux Falls, SD
GFC Installer:  Peterson Contractors, Inc.; Reinbeck, IA
GFC Designer:  Ground Improvement Engineering (formerly Geopier Midwest)

CASE HISTORY: L14 Flats – Omaha, NE

Project Description:

This is a four-story residential building in downtown Omaha.  It has maximum column loads of 265 kips and wall loads of 11.5 kips per lineal foot.

Subsurface Conditions:

The site had up to 20 feet of existing urban fill.  The design team had three choices to deal wiht the poor soils: deep over-excavation, pile foundations, or Geopier ground improvement.  They selected the Geopier approach due to low cost, speed, space constraints and also to allow for conventional footings.


Deanna Baker, P.E, with Ground Improvement Engineering (GIE) designed the Geopier GP3TM system to improve the fill and support normal spread footings.  The licensed installer for Nebraska, Peterson Contractors, Inc. installed 140 GP3 elements in a week.

GIE also designed a soldier pile and wood lagging retention system to protect an existing subgrade brick wall and an adjacent street.  Peterson installed steel H-piles, and helical anchors as tiebacks.

Project Team

Geopier Designer: Ground Improvement Engineering, Omaha, NE
Structural Engineer: Nielsen-Baumert Engineering – Omaha, NE
Geotechnical Engineer: Terracon, Inc. – Omaha, Nebraska
General Contractor: Dicon Construction – Omaha, NE

Read about this interesting project in Tulsa, where we used both the Geopier GP3 and X1® technologies to strengthen deep layers of fill.