Terrafirmer Rig

Densified Aggregate Piers
Telegraph Road Interchange
Alexandria, VA

As part of the mega Woodrow Wilson Bridge project, several sections of planned MSE walls were underlain by up to 20 feet of soft, compressible soils.  The Virginia Department of Transportation evaluated various alternatives for developing a solution to overcome the stability and settlement problems caused by the soft soils.  Predrilled densified aggregate piers were selected as the most cost-effective solution.  The design called for approximately 25,000 linear feet of aggregate piers spaced on a five-foot triangular grid pattern, and extending to depths of up to 20 feet.

TerraSystems was awarded the contract to install Terrapiers™ (our brand of predrilled densified aggregate piers) using both top-feed and bottom-feed techniques.  The holes were partially predrilled with a 30-inch auger using our LLM-40 Lodril drill rig.  Our Terrafirmer rig, which provides over 20 tons of centrifugal compactive force and over 25 tons of vertical compactive force, was used to construct the Terrapiers.