Edit shown in red. Typical timber pile embeddment for the South Carolina coast, with "granular sandy soil" per the OP's question. Few residences are built the V zone; most are in the A zones. Reasons for this:
1. The State owns all beaches up to the high tide line.
2. State law (SC Beachfront Management Act) establishes additional "set back" distances based on specific, local erosion rates.

From 10' to 20' embeddment, for for the A zone. See FEMA Home Builders Guide to Coastal Construction - Pile Design & Installation

www.SlideRuleEra.net
www.VacuumTubeEra.net

the building should be above the flood level including waves and the piles below the scour depth. if so, the scour could easily be 10 - 20 feet deep and the piles would need to go well below that to anchor the structure.

You need piles longer than 10 to 20 feet along the Florida panhandle. It also has alot to do with subsurface conditions. Our coastal residential projects typically involve piles embedded from 20 to 35 feet below existing grade. Most contractors jet the piles to within 5 to 10 ft of the designed tip elevation then drive the remaining distance. So you lose about 50% of your shaft resistance in the jetted zone.

cvg is right. You need to check scour depth as that is what typically governs the depth of piles along the coast.

during inundation and scouring, you cant count on any of that first 20 feet to provide any uplift capacity anyway, so jetting is the way to go It should be easy installation through beach sand, unless you hit debris or bedrock

Thanks guys. Pink stars all around.

Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com