It’s Not Delivery, It’s Dynamic Compaction-Paper

Paper

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The paper describes the use of deep dynamic compaction (DDC) to prepare an urban Milwaukee site for a 300,000-plus-square-foot industrial building. The property contained 10–25 feet of highly variable uncontrolled fill, including concrete rubble, foundry materials, slag, and debris, overlying natural clay. Voids and inconsistent fill strength raised concerns about differential settlement, while obstructions made conventional driven or drilled piles and other ground-improvement methods impractical or too costly.<br /><br />The project team selected DDC to densify the existing fill without removing it. A 30-ton tamper was dropped from heights of up to 60 feet over a primary 15-foot grid, followed by a secondary pass and a lighter finishing pass. Crater-depth records helped identify areas requiring additional treatment.<br /><br />Because nearby homes and other structures were vulnerable to vibration, the team used seismographs, installed a vibration-mitigation trench, and reduced impact energy in areas where monitoring approached established limits. The work was completed without exceeding those limits.<br /><br />Quality assurance included twelve plate-load tests. Eleven met the project’s performance criteria, supporting twice the assumed design load with less than a quarter inch of movement at design load. The single nonconforming result was affected by limited confinement beside the mitigation trench.<br /><br />The project demonstrates that DDC can economically and sustainably reclaim difficult urban sites: it reuses existing rubble, avoids extensive excavation or imported materials, and can make otherwise overlooked industrial land suitable for construction.

Keywords

deep dynamic compaction

urban industrial site

uncontrolled fill

differential settlement

ground improvement

vibration monitoring

plate-load tests

reclaimed land

settlement mitigation

Milwaukee site