Site Control, Decontamination, and Safe Work Practices
This domain tests whether you can keep a hazard from following a worker off the site - through zone control, a disciplined decontamination line, and the everyday work practices that prevent the quiet injuries.
The three zones
The exclusion zone is where contamination exists; only trained, PPE-equipped, logged-in workers enter it. The contamination reduction zone holds the decon corridor. The support zone is the clean side - command post, medical, rest, and eating area. Use one controlled entry and exit point, keep a log of who is inside, work in pairs with radio checks, and never let anyone wander between zones.
The decontamination sequence
Gross decontamination at the boundary - scrape, brush, or rinse, and drop tools. Then washing. Then a staged doffing: outermost garment first, rolling contaminated surfaces inward, bagging and labeling each item as it comes off. The respirator comes off last, and only after leaving the contaminated area. Finish with soap and water before street clothes. Tools and waste stay on the dirty side until cleared.
Safe work practices
No eating, drinking, smoking, or chewing gum in the exclusion zone. Wash hands before eating. Run work and rest cycles with hydration in heat, and acclimatize new arrivals gradually. Put a spotter on every piece of heavy equipment. Use lockout/tagout on utilities. Walk rather than run over debris, and never cut into an unknown wall, pipe, or line.
Worked example
A worker steps out of the exclusion zone with mud to the knee. Because the mud is contaminated, the boots are the first item addressed - wash them at the gross decon line, doff the outer boots, then the suit, then the gloves, and the respirator last at the clean line, followed by a shower. If that worker had walked into the support zone and pulled the boots off there, the cold zone would now be a contaminated area and everyone in it would need to decontaminate.
Traps that cost marks
Removing the respirator in the warm zone to talk; skipping decon because "it's just dirt"; running no entry log, so nobody knows who is inside when something goes wrong; and carrying contaminated PPE into a vehicle or home.