As a resident of Sun City Hilton Head, I use S.C. 170 daily and am aware of the ongoing construction there.
I am a licensed engineer in South Carolina and am concerned with the construction of this road. Proper installation of the roadbed should include a minimum of 3 inches to 4 inches of compacted gravel sub-base. An additional base course and wearing course of asphalt would be required.
Laying one inch of topsoil over the existing clay material will not be sufficient to safely carry the truck and private vehicle traffic.
The above recommendations are normally approved for public works projects.