Sterling, VA

Developer - Mark Fried Enterprises
Geotechnical Engineer - Soil Consultants

During construction of a large residential development in the 1960’s, a 10 acre site was used to spoil materials from site grading operations and building rubble. The spoil materials consisted primarily of clay, silt, and shale and diabase boulders. The proposed development included a one story shopping center, with Burlington Coat Factory as the main anchor store.

Due to the high cost of a pile foundation system, the geotechnical engineer recommended improving the ground with dynamic compaction and then using spread footings designed for a bearing pressure of 3 ksf.

Dynamic compaction was performed using an 8 ton weight dropped from a height of about 40 feet. Crater depths of up to six feet were created. Gravel and cobbles were primarily used as the crater backfill.

An enforced ground subsidence of about one foot was achieved across the site. Following treatment by dynamic compaction, a bearing pressure of 3 ksf was used for the project foundations.