A CNC Foundations excavator installs an aggregate pier using a vertical drill rig on a red clay construction site in Athens, Georgia. A gravel pile sits at the base of the rig, with another CNC loader in the background and rows of concrete casing pipes stacked on the left. Several service vehicles and construction workers are visible near the excavation wall.
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Close-up view of CNC Foundations equipment installing aggregate piers at a university housing site. A loader pours gravel into a drilled hole while the drill rig holds steady. Behind the equipment, large concrete pipes are lined along a safety fence near a roadway, and a CNC-branded excavator is positioned for support.
CNC Foundations crew members prepare a drill shaft for installation of aggregate piers on a compacted red clay site. Two workers in PPE guide the drill while surrounded by heavy machinery, including CNC-branded excavators and loaders. A soldier pile wall is visible in the background, supporting the excavation zone.

GROUND IMPROVEMENT USING AGGREGATE PIERS FOR UNIVERSITY HOUSING DEVELOPMENT IN ATHENS, GEORGIA

  • Athens, Georgia

CNC Foundations (CNC) provided engineered ground improvement using aggregate piers – also known as vibratory stone columns – to support a new 102,366-square-foot university housing complex in Athens, Georgia. The development, located near the University of Georgia campus, required a geotechnical solution capable of delivering consistent long-term performance in soils known for complexity and variability.

The project was led by Grahl Construction – the same general contractor behind Baldwin Village, a nearby 157-bed mixed-use development. Their experience with Athens’ transitional soil layers and excavation challenges made them an ideal partner. CNC’s solution improved bearing capacity, controlled settlement, and provided a cost-effective alternative to deep foundations while maintaining schedule efficiency in a dense urban setting.

  • Owner: Parker & Associates
  • General Contractor: Grahl Construction
  • Structural Engineer: Foresite Group
  • Project Timeline: 4 Production Days
  • Project Size: 102,366 sq ft
  • Design Bearing Capacity: 5,000 psf
  • Service: Aggregate Piers – Vibratory Stone Columns
  • Install Numbers: 300+ piers at over 3,500 linear feet
  • Market Sector: Commercial, Retail, and Office

The project required a foundation system capable of supporting multi-story residential structures on a site with variable soil profiles and deep transitional layers. CNC Foundations was selected to deliver a high-performance ground improvement solution that met strict load-bearing criteria while aligning with an accelerated construction timeline.

Subsurface investigation revealed the following conditions:

  • Loose sandy silt and silty sand near the surface

  • Partially Weathered Rock (PWR) encountered at depths from 33.5 to 88.5 feet

These conditions demanded a ground improvement solution that could densify loose surface soils and bridge deep transitional zones to ensure consistent, long-term support across the site.

CNC Foundations installed over 300 aggregate piers – also known as vibratory stone columns – totaling 3,500+ linear feet, using a vibratory flot to place and compact stone in staged vertical lifts from design depth to grade. This ground improvement system achieved bearing capacities up to 5,000 psf, maintained settlement within required tolerances, and delivered consistent performance across variable soils – all while allowing for fast, low-disruption installation on an active construction site. 

The full scope was completed in just four production days, keeping the development on schedule and within budget.