White Marsh, MD

Developer - Genstar Stone Company
Geotechnical Engineer - Century Engineering

A proposed three-story townhouse development was underlain by old fill soils consisting of construction rubble and a heterogeneous mixture of silt, sand and clay. The primary concern with development at the site using shallow foundation support was in the potential for excessive settlement. A number of alternatives were evaluated to overcome this problem, however, dynamic compaction was the only financially feasible alternative.

A total subsidence of the ground surface of 1.0 to 1.5 feet (approximately a 10 percent strain) was achieved by dynamic compaction. Standard penetration testing performed after the dynamic compaction verified an allowable bearing pressure of 3 ksf.

Dynamic compaction was performed using an 8 ton weight. Since the townhouse blocks were not predetermined, it was necessary to compact the entire site.