All operating and storage rooms and departments of inspected plants used for inedible material shall be maintained in clean condition, and shall be separate and apart from rooms and departments where certified products are prepared, handled, or stored. Docks and areas where cars and vehicles are loaded, and driveways, approaches and alleyways shall be properly paved and drained and the outer premises of every inspected plant shall be kept in clean and orderly condition. All catchbasins on the premises shall be of such construction and location and shall be given such attention as will insure their being kept in acceptable condition as regards odors and cleanliness. The accumulation on the premises of any material in which flies may breed, or the maintenance of any nuisance on the premises shall not be allowed.