Which methods can be used to prepare the subgrade?

Discing or scarifying is a method that can effectively prepare the subgrade for construction. This practice involves breaking up compacted soil to create a loose and workable surface, which is essential for proper drainage and preventing erosion. Discing slices through the top layer of soil, while scarifying involves raking or tearing at the soil to improve its structure and promote a better bond with any subsequent materials that will be placed on it, such as gravel or asphalt.

These actions enhance soil aeration, increase permeability, and remove debris or organic matter that might otherwise hinder construction processes. By properly preparing the subgrade in this manner, subsequent layers laid over it can adhere better, resulting in a more stable final surface.

Other options mentioned may touch on aspects of site preparation but do not specifically focus on tasks designed to condition or enhance the surface of the subgrade in the same effective way as discing or scarifying does.