Construction Concerns: Grain Storage Facilities

Article and photos by Gregory Havel

The grain storage structures shown in the photos are common throughout North America. Although they are not designed for human occupancy, they play a significant role in the economic life of many communities. Structures and facilities like these are commonly used to store bulk grain, animal feed, fertilizer, and other bulk commodities that must be protected from the weather and contamination.

Since the interior of these facilities is not designed for human occupancy, has restricted means of entry and egress, contains materials that can engulf anyone who enters, and may contain oxygen-deficient atmospheres or explosive dust, these facilities are considered by the Occupational Safety and Health Administration (OSHA) to be “permit-required confined spaces” under 29 CFR 1910.146.

 

Since these facilities use machinery that is interconnected and that can be started automatically or from remote locations, they are also covered by OSHA’s regulations on the control of hazardous energy (lockout/tagout) in 29 CFR 1910.147. This machinery includes elevators, distributors, conveyors, augers, floor sweeps, ventilation fans, and grain dryers. To protect our people working at an incident at one of these facilities, we must apply our own locks and tags after de-energizing the energy sources. These are complex mechanical systems and may require 10 or more locks and tags to lock out all of the machines after they are de-energized. We should insist that the facility managers apply their locks and tags with ours so that after we are completed and unlocked, they can verify the status and operability of the machinery before using it.

 

Some of the commodities stored in facilities like these are classified as hazardous materials by the Department of Transportation, OSHA, and the Environmental Protection Agency. One of the most common of them is ammonium nitrate fertilizer, UN 2071, UN 2072, or UN 2067.

 

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Photo 1 shows a large grain storage facility with steel bins ranging from a few thousand bushels (left) to hundreds of thousands of bushels (center) to millions of bushels (right). Also visible are the vertical elevator legs with access ladders, horizontal conveyors and walkways along the tops of the bins, and the diagonal gravity chutes from the distributors at the tops of the elevators to the conveyors or bins.

Not visible are the underground structures, including reinforced concrete tunnels under the bins that contain conveyors; ventilation fans, and ducts; and the “sweeps” on the floors of the largest bins. They are automatic augers that rotate slowly on the floor of an almost empty bin to ensure that the bin can be emptied as completely as possible without having a worker enter.

 

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Photo 2 shows a smaller grain storage facility with a vertical elevator leg with access ladder; horizontal conveyors and walkways; and diagonal gravity chutes.

The bins in photos 1 and 2 are constructed of horizontally corrugated curved sheets of galvanized steel that are bolted together. Several of the bins in these photos show vertical columns on the outside of the bins, attached with the same bolts that join the corrugated panels. The other bins have their columns inside the bin, attached in the same way. These two types of construction are typical of these storage facilities. Note that both the columns and the corrugated panels are essential load-bearing parts of the structure and that care must be exercised in cutting openings for rescue or for other purposes. If an opening is cut in the wrong place, is made too large, or cuts columns, the bin may partially or totally collapse.

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In photos 2 and 3, note the enclosed access ladders that are part of the elevator leg, the rest platforms and machinery access platforms at several levels, and the overhead electric utility wires. Should there be a fire at the top of an elevator leg or in a conveyor motor or should a medical emergency occur, access will be limited. The conveyors across the top of the storage bins can be 75 feet or more above the ground; access by aerial apparatus is limited to spaces between the bins unless overhead wires block these spaces. The upper platforms on an elevator leg will be beyond the reach of most aerial apparatus. The only access will be by vertical ladder. If there is a medical emergency involving a patient who cannot self-evacuate, removal will constitute a challenging technical rescue.

 

Rescue of a person from inside a bin or from a conveyor or ventilation tunnel below will also be a technical rescue; a permit-required confined space entry according to OSHA’s 29 CFR 1910.146, including air monitoring; and will require control (lockout) of hazardous energy, including electrical service and motors for conveyors, elevators, sweeps, and any other equipment that may provide a hazard. You will need technical advice by telephone or in person from the equipment manufacturer.

 

Lack of maintenance of electrical and mechanical equipment, which is difficult to access and which is exposed to the weather, is a common additional hazard in many of these facilities.

 

These facilities need preincident planning. Personnel need training on the types of technical rescues that may be required as well as periodic refresher training on the facilities’ features and hazards and on our plans to safely deal with them.

 

Detailed information on hazardous products that may be stored in the type of facility shown in the photos is available in the Emergency Response Guidebook (ERG), published by the Departments of Transportation of the United States, Canada, and Mexico. The ERG is available online at no cost at http://phmsa.dot.gov/hazmat/library/erg The Web site includes English and Spanish versions as well as a downloadable version designed for use on mobile electronic devices there is also an online training program on the use of the ERG.