Three Samples, One Percent, and an Inaccessible Chase
A pre-1980 former textile mill is being converted to apartments in Lancaster. The inspector divided the building into eight homogeneous areas and collected three bulk samples from each, except a pipe chase that could not be opened. The sprayed-on fireproofing on the structural steel is a 6,000-square-foot homogeneous area; PLM results are 0.5% chrysotile, 0.8% chrysotile, and 1.2% chrysotile. The owner's contractor calls the fireproofing "less than one percent" and proposes to remove it as non-ACM with a skid-steer and no containment. The pipe chase contains old fibrous insulation that the inspector labeled "assumed ACM" because the access panel was welded shut. The owner wants to exclude both materials from the abatement bid to reduce cost. The project designer asks for your assessment.
1. Is the sprayed-on fireproofing ACM and RACM? Explain the 1% rule and how the three sample results should be interpreted.
Read the worked answer
The fireproofing is ACM. Under OSHA, AHERA, and NESHAP, a material is asbestos-containing if it contains more than 1% asbestos. A homogeneous area is evaluated as a unit, and one sample above 1% makes the area ACM; the contractor cannot average 0.5%, 0.8%, and 1.2% to get a number below 1%. The 1.2% result is therefore controlling. The 0.5% and 0.8% reports are also not a reliable basis for calling the material non-ACM because PLM quantification below 1% is approximate and is often reported as trace. Sprayed-on fireproofing is a friable surfacing material, so if it is ACM it is also RACM. Removing it with a skid-steer without containment would crumble and pulverize the material, create visible emissions, and violate the requirement to use wet methods and engineering controls. The project designer should treat the fireproofing as RACM and require containment, decontamination, air monitoring, and proper waste handling.
2. Was the inspection and sampling adequate? Address homogeneous areas, sample numbers, and the inaccessible pipe chase.
Read the worked answer
The inspection is incomplete. Three bulk samples per homogeneous area is the usual minimum for a friable homogeneous area, but sample number is not the only test of adequacy. Borderline results, such as two samples below 1% and one above 1%, call for additional samples or a more definitive analysis before the area is characterized, especially when the owner wants to avoid abatement. More importantly, the pipe chase was never inspected. An inaccessible space cannot simply be excluded from the assessment. The inspector should attempt access by opening the panel, using a borescope, or arranging access with the owner. If access is impossible, the material must be assumed to be ACM and managed as such until sampling proves otherwise. The owner's desire to reduce cost does not override the need to inspect accessible areas and assume ACM in inaccessible areas. The report should clearly state the assumption, the limitation, and the recommended follow-up.
3. How should the pipe chase and the fireproofing be addressed in the bid and work plan?
Read the worked answer
Both materials must be carried in the bid as asbestos work. The fireproofing is ACM/RACM based on the 1.2% result, so the work plan must include a negative-pressure enclosure or equivalent containment, wet removal methods, decontamination, HEPA filtration, air monitoring, and labeled waste packaging. The pipe chase should be bid as assumed ACM with a defined unit price or provisional quantity, because the actual amount cannot be seen. The contractor should include the cost of opening the chase, sampling the insulation if access is gained, and handling the material as ACM if it is confirmed or remains inaccessible. The work plan should sequence the chase work so that a change in scope does not delay the project. If the owner insists on excluding either material, the designer should refuse unless the chase has been validly sampled and the fireproofing result has been resolved with additional sampling and analysis. Excluding known or assumed ACM from the bid creates a predictable change order and a compliance problem.