Abatement Work Practices, Containment, and Engineering Controls
This domain tests the sequence and physical controls that keep asbestos inside a regulated area: notification, containment, negative pressure, wet methods, HEPA cleanup, waste handling, and clearance. DC projects must also meet NESHAP-style notification thresholds, so expect arithmetic and sequencing questions.
Before abatement starts
- Confirm the asbestos survey and scope. The regulated area is marked with warning signs; access is limited to certified workers.
- Notify DOEE at least 10 working days before starting a project that meets the NESHAP threshold: 160 square feet of regulated material on facility components, 260 linear feet on pipes, or 35 cubic feet of debris. Smaller DC-notifiable projects may still require notification; emergency provisions are narrow.
- Seal the room with critical barriers over openings and penetrations. Build a decontamination unit with a clean room, shower, and equipment room. Install HEPA negative-pressure machines and verify negative pressure with a manometer; exhaust must not recirculate into occupied space.
Work practices and waste
- Use wet methods and HEPA vacuums. Dry sweeping, ordinary shop vacuums, and grinding are prohibited because they aerosolize fibers.
- Remove materials in intact sections where possible; use glove bags for pipe runs. Bag waste in labeled, leak-tight containers, typically double 6-mil bags, with rigid containers for sharp debris.
- Clean daily and before clearance. After final cleaning, an independent visual inspection and clearance air sampling at 0.01 f/cc PCM are required before containment is removed and the area is reoccupied.
Worked example
A crew will remove 200 square feet of acoustic ceiling tile in a DC school. Reasoning: 200 square feet exceeds the 160-square-foot NESHAP threshold, so DOEE notification is required at least 10 working days ahead. The crew builds critical barriers, a three-stage decon unit, and negative pressure. A worker proposes a shop vacuum for debris; that is rejected because it lacks HEPA filtration. After removal, they wet-clean, HEPA-vacuum, pass visual inspection, and obtain a clearance sample of 0.008 f/cc. Only then may containment come down.
Traps that cost marks
- Mixing up the 160-square-foot and 260-linear-foot thresholds.
- Treating notification as something the certified worker files personally; the regulated firm/employer is responsible.
- Using a normal vacuum or dry sweeping “just for the final cleanup.”
- Removing poly sheeting before clearance results are available.
- Allowing eating, drinking, or smoking inside the regulated area.
- Assuming negative pressure is present because the machine is running; it must be verified with a manometer.