Several Questions
1. What is the level of water in the swamp in relation to the proposed height of the roadway
2. Is the location subject to flooding from the sea at high tide etc
3. What is the proposed construction of the roadway. Any surfacing etc
4. What type of vehicles are going to use the drive way - half tons towing trailers, cars, trucks etc
5. Is this intended to be a serious permanent roadway or haul road.
With sand there is always the possibility of erosion, hence reason for some of the queries. However, sand forms agood subgrade if well confined.