A method of operating a dump tank of a polymer production process by transferring all or a portion of a content of a polymerization reactor into the dump tank, wherein the reactor contents comprise solid polymer, and liquid and gaseous non-product components, and removing at least a portion of the liquid and gaseous non-product components from the dump tank by: reducing a pressure of the dump tank, subjecting the solid polymer to a first cleaning stage comprising heating the solid polymer by introducing a first heated treatment gas into the dump tank, and subjecting the solid polymer to a second cleaning stage comprising purging the solid polymer by introducing a second heated treatment gas into the dump tank.