Dynamic Compaction for Unclassified Debris.
A leading global technology company is constructing a new headquarters and production plant for its U.S. business on an undeveloped property in New Berlin, Wisconsin. The planned development is taking place on a combined seventy-seven acres with a total of 525,000 SF of research, production, and warehouse space split between two adjoining buildings. The building site sits on a former peat farm, where over the past 30 years peat was mined in depths up to eighteen feet. As the peat was mined, the Owner re-established the existing grade by accepting imported materials consisting of a mixture of soil and various construction debris. The imported materials were dumped, spread, and leveled without engineering control, resulting in a 5 to 18 feet thick layer of construction debris.
The debris, which included large chunks of reinforced concrete, brick, asphalt, crushed stone, gravel, and timber, was not conducive to many of the commonly used ground improvement or foundation techniques. With the largest fleet of duty cycle cranes in the ground improvement industry, Malcolm Drilling collaborated with local geotechnical engineers to develop, budget, and execute a Dynamic Compaction solution. To treat depths up to eighteen feet, Malcolm custom-built two 8-foot diameter tampers that weighed 60,000 pounds each. The weights would be dropped from a height of sixty feet in an offset primary/secondary pattern multiple times over multiple passes on nearly 5,000 drop points.
To confirm that the dynamic compaction was effective, Malcolm Drilling utilized a series of plate load tests to confirm bearing capacity at various footing, column, and slab locations throughout the improved zone.