Abatement Work Practices and Contractor Licensing
What this domain tests
This domain tests whether you know who may legally perform abatement and how the work must be contained, monitored, cleaned, and cleared. Delaware licenses asbestos abatement contractors and certifies workers and supervisors through its Division of Public Health asbestos program; federal OSHA worker-protection rules apply on the job.
Core rules and concepts
- Licensing and certification: The contractor must hold a state asbestos abatement contractor license. Workers, supervisors, inspectors, management planners, and project designers must hold individual certificates from approved training. Typical training hours are 32 for workers, 40 for supervisors, 24 for inspectors, 16 for management planners, and 24 for project designers, with annual refreshers.
- Containment: Establish a regulated area with warning signs, critical barriers, a negative-pressure enclosure, HEPA filtration, and a three-stage decontamination unit (clean room, shower, dirty room).
- Work practices: Use wet methods, HEPA vacuums, glove bags where appropriate, and leak-tight waste bags. Dry sweeping, compressed air, and dry scraping are prohibited.
- Monitoring: Personal exposure monitoring compares results with the OSHA 8-hour permissible exposure limit of 0.1 f/cc and the 30-minute excursion limit of 1.0 f/cc. Clearance requires a visual inspection plus aggressive air sampling; a common AHERA-style clearance criterion is PCM below 0.01 f/cc.
- Medical surveillance and respirators: Fit testing, medical clearance, and training must be current before respirator use.
Worked example
A supervisor notices dry sweeping in the enclosure and a pressure gauge reading −0.005 inches of water. The project specification requires −0.02 inches and HEPA filtration. Clearance samples later read 0.008, 0.009, and 0.012 f/cc. The correct response is to stop work, correct the containment and work practices, reclean, and re-sample. The 0.012 result fails the 0.01 criterion even though two samples passed. Allowing occupancy because “most samples passed” is a clearance failure.
Traps that cost marks
- Assuming a contractor license covers individual workers; both contractor licensing and worker certification are required.
- Treating clearance as visual only; air sampling is required.
- Confusing the 0.1 f/cc PEL with the 1.0 f/cc excursion limit.
- Accepting a negative-pressure gauge reading that is too close to zero.
- Allowing dry sweeping or compressed air because the material is “wet.”