Method of handling proppant at a well site using a plurality of modular proppant containers in which first and second modular proppant container in a filled state are removed from delivery transport vehicles and transferred to first and second cradle positions on a support structure using one or more heavy-duty handlers. Proppant is discharged by gravity feed from the outlet of the first and second modular proppant containers and directed to a hopper until the modular proppant containers are in an empty state.