Challenge
The site for the proposed six-story Hilton Hotel near the airport in Norfolk, Virginia, had about 20 feet of loose sand over soft clay, with groundwater just 6–8 feet below the surface. Engineers initially considered deep foundations, but the cost was too high.
Solution
The team opted to improve the loose sand using dynamic compaction to allow for the use of shallow foundations. An 8-ton weight was dropped from 50–60 feet, creating craters up to six feet deep that were filled with clean sand.
Outcome
After treatment, tests showed the ground could safely support the structure, and the hotel has operated since 1985 with no settlement problems.
