California Code of Regulations
Title 8 - Industrial Relations
Division 1 - Department of Industrial Relations
Chapter 4 - Division of Industrial Safety
Subchapter 7 - General Industry Safety Orders
Group 3 - General Plant Equipment and Special Operations
Article 15 - Vats, Pans, Bins, Bunkers, Hoppers, and Similar Containers and Vessels
Section 3481 - Bins, Bunkers and Hoppers

(a) Every open bin, bunker and hopper whose upper edge is less than 36 inches above floor or working level shall be equipped with a standard railing around its edges or a grating or grille shall cover the top. Where grille or grating is the only protection it shall have no opening whose least dimension exceeds the following: 2-inch maximum openings for essentially smooth surface material with one-half inch maximum particle length (such as but not limited to sand, powder, grains, seed and pea gravel); 6 1/2 -inch maximum openings for irregular surface material with one-half inch maximum particle length (such as but not limited to cottonseed); and 10-inch maximum openings for all other material with particle length exceeding one-half inch (such as but not limited to crushed rock and ore).

NOTE: Where railings are used they may be temporarily removed to provide necessary working openings.

(b) The grating or grille shall be of strength sufficient to withstand any load that is customarily imposed upon it.

(c) Where bins, bunkers or hoppers are loaded by automotive truck or other wheeled equipment, bumper stops presenting a vertical face not less than 10 inches high shall be installed at 1 edge in a manner to prevent the equipment from running onto or over the hopper.

EXCEPTION: Dumping spots used exclusively by bottom dump vehicles or hoppers designed for vehicle traffic load.

(d) Curbs having a vertical face of not less than 8 inches high shall be securely fastened along the sides to prevent a vehicle from overrunning the side of the runway.

(e) Where employees are permitted or required to work in or above open top bins over 8 feet in depth, an upper working area consisting of a platform or walkway shall be provided, and shall be guarded with a standard railing and toeboard.