A proppant storage vessel has a first container with an interior volume, and a second container supported in spaced relation above the first container. The first container has a bottom hatch affixed to a bottom wall thereof. The bottom hatch is movable between an open position and a closed position. The first container has an opening at a top wall thereof. The second container has bottom hatch formed on a bottom wall thereof. The bottom hatch of the second container is aligned with the opening of the first container such that a proppant in the second container can flow through the hatch thereof into the interior volume of the first container. Each of the containers includes first, second, third and fourth inclined surfaces positioned in the interior volume and extending from the respective side walls and end walls thereof toward the bottom hatch.