Unplacarded Tanker on Its Side, Product Pooling, School Downwind
At 14:05 you arrive on a two-lane highway at an overturned tank vehicle. The trailer is on its side and unplacarded on the visible side. A clear, volatile liquid is running from a 3-inch crack near the dome, pooling about 40 feet across. The driver is conscious but pinned in the cab and complaining of eye irritation. The wind is from the west at 8 mph. A school with children on the playground is 400 feet east and directly downwind. The nearest hydrant is 1,200 feet west. Your engine carries 750 gallons, a 1,500 gpm pump, SCBA for four, and no Level A suits. Traffic is still moving past on the shoulder.
1. What is your initial isolation, and do you attempt to free the driver? Justify the answer on capability, not on sympathy.
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Isolate first, and isolate uphill and upwind. For an unidentified liquid from an overturned tank, the ERG's isolation guidance for unknowns is a starting point, not a finish line - 150 feet in all directions for a small spill, more for a large one. A 40-foot pool off a 3-inch crack is not a small spill, and the school at 400 feet downwind tells you the real hot zone is longer than a default table. Establish at least a 150-foot perimeter, expect to expand it, and stage the engine west and uphill.
On the driver: do not enter. He is pinned, which means a rescue would be a slow, tool-intensive operation inside a vapor cloud of an unknown volatile liquid that has already produced eye irritation from a distance. You have SCBA but no vapor-protective suits, no chemical gloves, and four cylinders. Structural PPE absorbs and holds vapors; it is not splash protection against an unknown. A rescue attempt that puts two firefighters down inside the hot zone converts one patient into three and pulls the only resources away from protecting 400 feet of downwind children.
Instead: request HazMat and technical rescue immediately, keep the driver calm and talking from a distance, and ask him what he is hauling. He is your fastest identification source.
2. How do you identify the product without sending anyone into the hot zone?
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Identify from where you stand, using the documents and markings that are already outside the vapor cloud.
First, the driver: he is conscious. Ask him the product name, the UN number, and whether he has shipping papers. In an overturned tractor-trailer the papers may be in the cab with him, or in a document holder on the outside of the trailer or the tractor door.
Second, read markings from upwind with binoculars: the orange panel on the far side or the rear, the specification plate (a DOT 407 or 412 tells you it is a cargo tank and narrows the product class), any corrosion-resistant lining markings, and the commodity label on the rear head.
Third, call. Dispatch contacts CHEMTREC or CANUTEC with the carrier name from the door and the trailer number; the carrier knows what was loaded and where it was going.
What you do not do: walk to the trailer to read a placard, or use a sense of smell to identify a product. "Smells like gasoline" is not identification, and the vapor is the hazard.
3. The school is 400 feet downwind with children outside. What is your action, and how do you set up command and notifications?
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The school is the priority exposure and it is a communications problem more than a fire problem.
At 8 mph, vapor at 400 feet arrives in under a minute of travel time at ground level. Getting children back inside, closing windows and doors, and shutting down the HVAC is faster and safer than evacuating them across the path of the cloud. Call dispatch and have them contact the school directly to shelter in place - that is the message: "close up, stay inside, HVAC off, do not evacuate." If the wind shifts or the pool grows, revisit it and move them upwind instead.
Command: establish a stationary command post upwind and uphill, announce the location, and name the isolation perimeter aloud so incoming units do not drive into it. Assign someone to traffic control immediately - moving cars on the shoulder are a moving ignition source, and the responders working the scene are standing next to them.
Notifications in order: dispatch (school, HazMat, EMS, police, state environmental agency), then the IC's resource requests. Do not commit engine water to an unknown product; keep the 750 gallons for fire protection of exposures only.