Page 8 - UFRA Straight Tip Spring 2021 - Volume 22 Issue 2

RISK-BASED RESPONSE FOR UNKNOWN MATERIALS
Solid
Liquid
By making assumptions based solely on the physical state, there are reliable actions that can be taken for a safe risk-based response.
A 50-pound, brown paper bag with clear plastic lining has broken
on the roadway, and several cars have driven through it. The spilled, off-white dust is now spread down the road for 100 feet. A one-gallon, white plastic jug is leaking a thick, dark, unknown fluid in a parking ga- rage. A loading dock worker notices a faint hissing noise coming from
a silver compressed gas container that is about one foot in diameter and two feet in height. In a response to any of these cases, what would you do? These should be the first steps:
• Isolate and deny entry. How far? 50 feet for a solid, 150 feet for a liquid, and 300 feet for a gas.
• Make notifications. Who do I call? Usually, lacking informa- tion, a technician team is needed.
• Attempt to identify the material. Can I identify it? No, I have no idea what it is. Without positive identification of the material, can I do anything? Absolutely yes, and you should.
To attempt to identify an unknown material, start with the physical state of the material—in the examples above, a solid, a liquid, and a gas. By making assumptions based solely on the physical state, there are reliable actions that can be taken for a safe risk-based response.
A material such as a powder, pellets, prill, briquettes, tablets, crystals, chunks, slabs, or fibers is most likely either a salt compound, a natural product, or a metal. Only salt compounds pose significant hazards. Solids should not be allowed to get airborne, but if they do, they won’t travel far and will obey wind direction and speed.
There are few flammable solids, and they have low vapor pressures, so don’t worry too much about ignition sources. Some salts are water reac- tive, so if it’s dry, keep it dry. A tarp will keep any rain off the bulk of the spill. There’s a reason the bag in our first example had a plastic liner—the material is meant to be kept dry.
Salts vary greatly in toxicity, so let’s not touch it. PPE for solids is what you have available. Turnout gear and SCBA with double latex or nitrile gloves would be more than safe. Decon should consist of a charged line deployed on soil (if possible) to reduce and control runoff and facilitate an easier environmental clean-up.
Liquids are trickier than solids because above every liquid there is vapor, which creates additional hazards. Liquids have wide degrees of viscos- ity, vapor pressure, odor, color, and toxicity. Viscosity tells us something about volatility but nothing about toxicity. Liquids with low viscosity, meaning low resistance to flow, are sometimes called “lively” liquids. These lively liquids are likely more volatile with higher vapor pressures. Higher viscosity of a liquid, or the greater the resistance to flow, means the liquid will be a thicker, slower compound that is likely to have lower volatility and low vapor pressure.
A tarp could be used to suppress vapors, since the spill in our example is localized, and positive pressure fans could be used to direct vapors away from vulnerable areas or exposures. With any kind of vapor dispersion, whether outdoors or inside a building with an exterior opening, you must control and monitor where you’re sending the vapors.
Liquids are dependably non-salts, and they’re all toxic. Non-salts are typically flammable or combustible, so any sources of ignition should be controlled. If a liquid does ignite and the situation calls for fire suppres- sion, I would consider using a polar foam or all type concentrate foam. Water will most likely run off because most liquids are non-polar.
The size of the spill can make a difference. In our opening scenario, the one-gallon, unmarked white plastic jug unattended in a parking garage, presumably an abandoned container, is a small quantity. That’s in our favor. Small spills are easily absorbed or adsorbed by spreading loose material directly on the liquid or using pads and rolls around the spill to control it.
The color of a liquid doesn’t tell us much. Our life experiences give us some familiarity with certain colors, viscosities, and smells of
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