Cleanup, decontamination and waste management

Once a spill is stopped and contained, the work is not over. The liquid has to be recovered, surfaces cleaned, tools and people decontaminated, and every pad, sock, glove and shovelful of soil handled as waste. Done well, cleanup leaves the area safe and the waste properly documented. Done badly, it spreads contamination, exposes workers and creates a second violation when contaminated waste ends up in the regular garbage. This lesson covers each stage and the waste rules that apply.

Recovering the spilled material

Recover as much liquid as possible before using absorbents, because absorbents turn a liter of liquid into several kilograms of solid waste. Pump or scoop pooled liquid into a compatible container. Then soak up what remains with absorbents, working from the outside of the spill toward the center so that the spill does not spread. Leave absorbents in place long enough to soak up the liquid, then collect them with a non-sparking shovel or by hand with gloves, and place them in heavy-duty bags or a drum. Do not overfill bags; a bag of saturated absorbent is heavy and can split.

For powders and granular solids, avoid creating dust. Scoop or vacuum with a vacuum rated for the material, rather than dry sweeping. For broken containers, place the leaking container in an overpack drum or salvage drum. For mercury from broken thermometers or switches, use a mercury spill kit; never vacuum mercury with an ordinary vacuum, which spreads vapor.

Cleaning the surface

After the bulk of the spill is recovered, a film usually remains on the surface. Use granular absorbent worked into the surface and swept up, or a cleaner recommended for the substance, applied sparingly and recovered with absorbent. Do not wash the area down with a hose, because that sends the remaining contamination to drains and soil. On porous surfaces such as concrete, some staining may remain; that is normal, but it should not be left slippery or giving off odor. On soil, as lesson 8 explained, contaminated soil may need to be excavated by a contractor.

Decontamination

Decontamination removes the spilled substance from people, tools and equipment so that it does not spread or harm anyone later. For small oil and fuel spills, this usually means removing gloves and disposable coveralls carefully, turning them inside out as they come off, placing them with the spill waste and washing hands and any exposed skin. Reusable tools such as shovels and squeegees are wiped clean with absorbent and a suitable cleaner, and the wipes go into the waste. For hazardous chemicals, decontamination follows the safety data sheet and the site plan and may involve a set sequence of washing stations.

Never take contaminated clothing home to wash with family laundry. Clothing soaked with fuel or solvent is a fire hazard and can expose others; it should be removed promptly, bagged and either cleaned by a service that handles contaminated workwear or disposed of as spill waste. Workers who were splashed should follow the first aid measures in section 4 of the safety data sheet.

Spill waste is waste

Everything that touched the spill is waste: used absorbents, pads, booms, rags, contaminated soil and gravel, recovered liquid, disposable protective equipment and broken containers. Whether that waste is hazardous depends on what was spilled and the rules where you are. Absorbents soaked with gasoline or solvent, acids or pesticides are usually hazardous waste. Absorbents with used motor oil may be managed under used oil or waste oil rules. Absorbents from a spill of water-based paint may not be hazardous at all. The safety data sheet, the site's waste procedures and, where needed, laboratory testing decide.

The basic rules are the same everywhere. Keep spill waste separate from regular garbage and from other wastes it could react with. Put it in containers that are compatible with it, closed and in good condition. Label every container with what is inside, the hazard and the date. Store it in a secure area with secondary containment, out of the rain, until it is picked up by a licensed waste carrier and taken to an authorized facility. Never put spill waste in the regular garbage, burn it, bury it on site or pour recovered liquid down a drain.

Hazardous waste rules in the United States

In the United States, hazardous waste is regulated under the Resource Conservation and Recovery Act, usually through state programs that may be stricter than the federal rules. A generator's category depends on how much hazardous waste it produces in a calendar month. A very small quantity generator produces 100 kilograms or less of non-acute hazardous waste a month; a small quantity generator more than 100 but less than 1,000 kilograms; and a large quantity generator 1,000 kilograms or more, or more than 1 kilogram of acute hazardous waste. Small and large quantity generators must use the uniform hazardous waste manifest, which is now tracked electronically through EPA's e-Manifest system, and must meet accumulation time limits and training requirements. Used oil, including absorbents with used oil that are not hazardous waste, may be managed under the separate used oil management standards. While on the road, hazardous waste is also a hazardous material under DOT rules, covered in HSE-250.

How much waste a spill creates

Spill waste is heavier than people expect. Absorbents hold several times their own weight of liquid, and the saturated material weighs about the same as the liquid plus the absorbent. Contaminated soil weighs around 1.5 to 2 metric tons per cubic meter. A modest spill can therefore create enough waste to change a site's waste category or fill a bin, as the example shows.

# Waste created by a 60 L diesel spill cleaned up with absorbents (illustrative).
spill_L = 60
recovered_by_pump_L = 20                 # liquid pumped straight into a drum
diesel_kg_per_L = 0.84
to_absorb_L = spill_L - recovered_by_pump_L
absorbent_capacity = 3.0                 # L absorbed per kg of absorbent (product dependent)
absorbent_kg = to_absorb_L / absorbent_capacity * 1.5    # 1.5x: absorbents are never fully used
waste_solid_kg = absorbent_kg + to_absorb_L * diesel_kg_per_L + 3   # + gloves, bags, PPE
print(f"Pumped liquid: {recovered_by_pump_L} L ({recovered_by_pump_L*diesel_kg_per_L:.0f} kg)")
print(f"Absorbent used: about {absorbent_kg:.0f} kg")
print(f"Solid spill waste: about {waste_solid_kg:.0f} kg ({waste_solid_kg*2.2:.0f} lb)")
soil_m3 = 0.5
print(f"If 0.5 m3 of soil must also be dug out: about {soil_m3*1.8:.1f} t more")

Pumped liquid: 20 L (17 kg)
Absorbent used: about 20 kg
Solid spill waste: about 57 kg (125 lb)
If 0.5 m3 of soil must also be dug out: about 0.9 t more

In the United States, hazardous spill waste counts toward the month's generation. A site that is normally a very small quantity generator could become a small quantity generator for that month because of one cleanup, which brings additional requirements. EPA rules provide some flexibility for episodic events such as spills, but sites must follow specific notification and management conditions; check the current rules and your state's requirements.

Closing out the spill

Before the response is declared finished, the area should be checked: no free liquid, no slippery film, no strong odor, drains clear and drain covers removed only after the area is clean. Spill kits are restocked. Equipment is cleaned and returned. Waste is labeled and stored for pickup. The spill report is completed, including the estimated volume, how much was recovered, where the waste went and photos. Finally, the cause should be investigated and fixed, so that the same spill does not happen again; HSE-403 covers incident investigation and root cause analysis in depth.

Recovered product and reuse

Sometimes recovered liquid can be reused or recycled instead of disposed of. Clean diesel pumped from a containment area into a clean, compatible container may be usable again if it has not been contaminated with water, dirt or absorbent. Used oil recovered from a spill can often go to a used oil recycler. Reuse should be decided by the supervisor following the site's procedures, because contaminated fuel can damage engines and mixed liquids may be hazardous waste. When in doubt, treat recovered liquid as waste.

Storing spill waste safely matters until it leaves the site. Bags of oily absorbent can leak and attract animals; drums can corrode; rags soaked with some oils and finishes can heat up and catch fire on their own as they oxidize. Keep spill waste in closed metal or approved containers, out of the sun and rain, away from ignition sources, and arrange pickup promptly rather than letting it build up.