Abstract: A method for cleaning tanks and other containers including, but not necessarily limited to, tanks associated with land-based drilling rigs and/or used in connection with hydraulic fracturing operations. Recoverable liquids and associated solids are first removed from a tank to be cleaned. A cleaning solution is prepared in a weir tank and sprayed into a tank to be cleaned. Sprayed cleaning solution, together with any debris or residue from the tank being cleaned, is pumped back to the weir tank and recycled for further cleaning.