Containment Breach in a Hospital Boiler Room
A licensed abatement contractor is removing 600 linear feet of friable boiler insulation in a hospital basement. The containment is 50 feet by 30 feet by 10 feet, or 15,000 cubic feet, built with 6-mil poly, one decontamination unit, and one HEPA air scrubber rated 1,000 cfm. The contractor calculates 4 air changes per hour and concludes one unit is enough. During the shift, a worker reports that the poly door flap is torn and visible dust is escaping into the corridor. The project monitor's pump shows 0.04 f/cc outside containment. Workers inside wear half-mask P100 respirators and disposable coveralls; they have been dry-sweeping debris because the HEPA vacuum is clogged. Bagged waste is single-bagged and stacked in the hallway. The hospital infection control staff wants the corridor reopened in 2 hours.
1. Evaluate the air scrubber sizing and negative pressure design.
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The containment volume is 50 x 30 x 10 = 15,000 cubic feet. Four air changes per hour require 60,000 cubic feet per hour, or 1,000 cfm. One scrubber rated 1,000 cfm at free air is marginal, not adequate: filter loading, duct length, and bends reduce actual airflow, and the unit must maintain negative pressure as filters load. A second unit or a larger unit with margin is needed, plus a magnehelic gauge or manometer to verify negative pressure. The contractor's arithmetic is correct, but the design is inadequate because it assumes perfect performance. The scrubber exhaust must be HEPA filtered and discharged away from occupied air intakes.
2. What should be done about the containment breach and the dry sweeping?
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On discovering the tear and visible dust, stop abatement, keep workers inside or move them through the decontamination unit, and prevent occupants from entering the corridor. Do not dry sweep. HEPA-vacuum and wet-wipe the corridor and containment surfaces, repair the poly with a proper patch and tape, and re-establish negative pressure. Verify with a smoke test or pressure gauge and air monitoring. Notify hospital infection control and the building owner, and investigate whether the outside 0.04 f/cc sample represents a release. The corridor should not reopen in 2 hours unless cleaning, visual inspection, and air monitoring are complete and acceptable. The clogged HEPA vacuum must be replaced or repaired before work resumes.
3. How should the waste be handled, and what must happen before the corridor is reopened?
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Single-bagged waste in a hallway is improper. Waste must be wetted, placed in leak-tight double 6-mil bags or sealed drums, gooseneck-taped, labeled, and stored in a designated area away from occupied spaces. It must be transported by a permitted hauler with a manifest to an approved landfill. The hallway must be HEPA-vacuumed and wet-wiped before reopening. Reopening should be based on visual inspection and air monitoring, not a fixed 2-hour clock. The contractor should also correct the dry-sweeping practice, because dry sweeping re-enters fibers into the air.