I am not aware of anything specific to the sand affecting turtle nesting. However, roots can reduce survival of the clutch by penetrating the eggs. In general I would expect beaches without much vegetation where the nests are being laid to do better than ones where the eggs are being laid with large plants nearby. Light pollution on the beach and foot traffic are probably more important. (You want to keep people from going and bothering the turtles while they're nesting or emerging, and if the beach has a lot of shops or houses with lighting adjacent to it you might want to put up some sort of opaque fencing to block the light; the ocean should be the brightest thing the hatchlings can see!)

Olive Ridleys nest in huge numbers all at once in phenomenon called arribadas. These occur on the same beaches on a yearly or bit early basis. So the same beaches are nested on, often by the same females. Human predation is their biggest threat as well as  bycatch. Keeping people, dogs,cars off the beach is very important. The Kemps Ridley nests in the daytime, but the Olive primarily at night. Keeping the beach free of debris helps a lot. The absence of artificial lighting is important for the hatchlings as well. Protection from human egg hunters is essential. The beaches generally have a gentle slope.

Nancy