A modular well containment cellar system having a bottom portion, two co-planar half-panels joined to the bottom portion and separated by a through-channel portion, and a one side wall joined to a bottom portion and to the half-panels, forming a closed container with an open top for mating to another cellar component at the half-panels, wherein a well pipe may be received into the through-channel. A plurality of drip diverters prevent downward-moving liquid from running between the mated half-panels and between the well pipe and the through-channel, to capture dripped and running liquids from above the containment cellar system.