Hazmat Site Storage: How Much is too Much?

warehouse full of chemical containers

How much hazardous material is stored at any given facility is probably something we could all have a better handle on. Knowing what is in a facility can be difficult enough, let alone knowing how much is there.

And if both of those are known, does that quantity of that material exceed the proper limit? That is a complicated question. It’s one hazmat team leaders will want to know if there’s an incident at a fixed site, and one they may be called upon to provide expertise in an inspection, business permit deliberations or when local codes are revised.

In her recent blog for NFPA, Valerie Ziavras outlined an eight-step process for determining the maximum allowable quantity of hazardous materials based on NFPA 1 (fire code) and NFPA 400 (hazmat code).

Step one is to determine what category the hazardous material falls under. NFPA 400 has 14 categories and it is possible that one material will come under multiple categories. When a material doesn’t match any of the categories in NFPA 400, other standards can be used to determine the type. For example LP gas storage and use systems can be found in NFPA 58 or 59.

Step two calls for determining occupancy use where the material will be stored. Ziavras says different occupancies could change how much material is allowed on site.

Step three involves determining how the material will be used. This too can change how much material is allowed. A site that only stores the material in an approved container or moves it from the container in a closed system not exposed to air are treated the same for maximum allowed quantity because they pose a lower threat. A site that uses an open system, where vapors can escape, will be given a lower allowed quantity.

Step four determines the baseline maximum quantity allowed, adjustments are accounted for. NFPA 400 has different tables for establishing this baseline for different materials.

Step five calls for determining how much additional material can be allowed based on additional protections the site offers. One example she sites is for organic peroxide. The baseline allowable quantity is 16 pounds. If a facility stores the material in an approved, appropriate container (such as a gas cabinet or safety can), the site is allowed 100% more material. If a building has sprinklers, another protection factor, the amount allowed goes up another 100%. So, for one added layer of protection, the amount goes from 16 pounds to 32 pounds — and up to 64 pounds for the second layer of additional protection.

Step six is where you determine how to adjust for multiple controlled areas. Some buildings, she writes, can have several controlled areas depending on where those areas are located. Again, there’s a table in NFPA 400 that makes that determination. The table spells out the fire resistance rating for the barriers separating the controlled areas. For example, if an area has a floor-to-ceiling wall with a fire resistance rating of one hour, those are considered two controlled areas.

Step seven addresses if the building design works. If a material being stored or used exceeds the maximum allowed quantity, the property owners can look at adding additional protections or additional controlled areas.

Step eight looks at the five levels of protection spelled out in NFPA 400. Levels one, two and three are protections from physical hazards — with level one offering the most protection. Level four covers health hazards, and level five is for semiconductor fabrication facilities.

“Any proposed change to the material, or the location of the material should be carefully evaluated to ensure quantities still fall below the MAQ, or the necessary additional protection requirements are met,” she writes.

Understanding and participating in this process could be lifesaving.

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