This paper presents a case in which dynamic compaction (DC) was used as site preparation for a proposed supermarket. The site was located immediately adjacent to a steep, 15 ft. high slope leading down to the Hudson River. Test borings revealed subsurface conditions consisting of uncontrolled miscellaneous fill extending 10 ft. below river level. Stability evaluations indicated that the slope was unstable under rapid drawdown conditions, and placement of the supermarket at the crest of the slope further decreased its stability. There were also concerns regarding possible differential settlement of the supermarket due to the variability of the fill. Dynamic compaction was selected as a cost-effective way to create a more uniformly dense foundation material, and to improve the factor of safety against deep seated slope failure. Verification test borings were performed after both the first and second DC passes. Vibration data obtained during monitoring of the DC program is presented