Inspection, Sampling, and Assessment
This domain tests whether an inspection would hold up: did you define homogeneous areas correctly, sample them properly, and assess condition well enough to drive an abatement or O&M decision?
Inspection sequence
Review drawings and prior reports, walk the building including concealed spaces above ceilings and inside chases, identify homogeneous areas by material and appearance, then sample. AHERA minimums for school inspections are three bulk samples per homogeneous area of surfacing material, three per homogeneous area of thermal system insulation, and at least one per homogeneous area of miscellaneous material. Wet the material, cut a full-depth core, seal it, and keep chain of custody.
Analysis and interpretation
PLM with dispersion staining at roughly 400x is the standard bulk method; the laboratory should re-analyze a percentage of samples as quality control. A report showing less than 1 percent with visible fibers may warrant a 400-point count or TEM before you call the material non-ACM. NESHAP regulates at 1 percent.
Assessment
Record damage and the likelihood of disturbance. Surfacing and TSI with significant damage in an occupied space push toward abatement or isolation; intact material in a low-traffic area may support an O&M plan. The management planner converts inspection data into response actions.
Worked example
A 1978 wing has 200 square feet of 12x12 tile plus mastic. The tile is one miscellaneous homogeneous area and needs at least one sample; the mastic is a separate homogeneous area and needs its own sample. If the tile returns 2 percent chrysotile, it is ACM and the mastic result decides whether removal includes scraping. If the mastic returns less than 1 percent with visible fibers, run a point count before writing the specification.
Traps
Compositing across different homogeneous areas. Sampling only the damaged patch and generalizing to the whole wing. Skipping concealed spaces. Accepting a lab report with no accreditation or QC data. Assuming a renovation survey equals a full AHERA inspection.