In 2020, Pratt Industries announced that it would construct a $500-million paper mill on its 200-acre complex in Henderson, Kentucky.  The soil conditions at the large site generally consisted of silty clay fill to depths ranging from two to 12 feet, underlain by very soft to stiff clay and silt to depths over 50 feet.  Bedrock was not encountered at this site during the geotechnical investigation.

The Geopier X1® Rammed Aggregate Pier® system was designed and installed to support this single-story 450,000 square foot paper and cardboard manufacturing facility.  The structure has slab loads on the order of 1,000 psf and column loads up to 170 kips.  In addition, up to 11 ft of grade raise fill was required to bring the site to grade.  The ground improvement solution was designed to mitigate large, anticipated settlements.

One PCI crew installed almost 6,100 Rammed Aggregate Pier elements to depths of 15 to 25 ft below existing grade to deliver an on-time schedule.  PCI partnered with Terracon to provide on-site construction monitoring.  Field engineers observed for drilled depth, amount of material placed in each location, and type of material encountered. Crowd Stabilization Testing was performed at a rate of 1 test every 10 holes drilled, and testing included compaction verification throughout the pier and dynamic cone penetrometer testing at the top of the pier.  PCI also performed full-scale field load tests to verify the in-situ behavior of the ground improvement elements in accordance with ASTM D1143.