Site control, decontamination, and safe work practices
Site control keeps contamination, people, and clean equipment from meeting. The exam tests the three-zone layout, the paperwork controlling entry, decontamination logic (including why you sometimes decontaminate dry before wet), and the work practices that keep a crew functional in encapsulating suits.
Zones and access
- Exclusion zone: the contamination source area; entry only with authorization, correct PPE, and a buddy.
- Contamination reduction zone: the buffer where decontamination happens; the decon line sits here.
- Support zone: clean area for command, medical, supplies, and rest, sited upwind and uphill where possible.
- A site map, wind direction, and an entry/exit log recording names, times, and PPE are baseline controls. Communications must reach every worker in the exclusion zone, and the buddy system is mandatory there.
Decontamination sequence
Plan decon before entry: station layout, tools, water and containment, and waste streams. Typical sequence: gross contamination removal (scrape or HEPA-vacuum dry material first), suit wash with detergent, rinse, boot and glove wash, removal of outer garments, then respirator doffing last, with each step physically separated so a worker never touches clean surfaces with contaminated gloves. Equipment gets the same treatment; reusable respirators are cleaned and disinfected, and decon water is contained and characterized as waste.
Safe work practices
Heat stress drives many real decisions: fluid and electrolyte replacement, work-rest cycles, cooled rest areas, and monitoring for cramps, confusion, and cessation of sweating. Add illumination, potable water, sanitation, no eating or smoking in contaminated areas, and traffic control around heavy equipment.
Worked example
A crew decontaminates lead-contaminated coveralls. Hosing them down first would spread lead-laden water and create a large wastewater stream. The correct order is HEPA vacuuming and bagging the dry dust, then detergent washing and rinsing, with runoff collected. The reasoning: remove the most contaminant with the least spread, and plan the waste before you make it.
Traps
Putting the decon line inside the support zone, letting workers skip equipment decon, and reusing the same outer gloves across wash and rinse steps. Another classic: planning decontamination after the entry instead of before it.