Averaging a Clearance Failure and Open Dumpster Waste
A contractor has removed 2,400 square feet of 9-inch by 9-inch floor tile and black mastic from a vacant office suite. The tile was removed with a low-speed floor machine and wet methods; the mastic was softened with solvent and scraped. Final clearance air sampling was performed with three PCM samples: 0.008, 0.012, and 0.004 fibers per cubic centimeter. Each sample was collected at 2 liters per minute for 200 minutes. The background sample was 0.003 f/cc. The contractor's report states that the average of the three samples is 0.008 f/cc, so clearance is achieved. Fifty-five bags of tile and debris are sitting in an open dumpster behind the building; the bags are not labeled, and some are torn. The disposal landfill has a permit to accept asbestos waste, but no waste shipment record has been prepared.
1. Determine whether clearance has been achieved, considering the sample results, averaging, and sampling method.
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Clearance has not been achieved. The applicable clearance criterion is typically 0.01 fibers per cubic centimeter or less for each sample under the state or AHERA-style protocol, not an average of the samples. The result of 0.012 f/cc exceeds that limit, so the suite fails even though the arithmetic average is 0.008 f/cc. Averaging can hide a localized release and is not an acceptable substitute for sample-by-sample evaluation. The sample volume is 400 liters, which is within a normal range for PCM sampling, but the contractor should verify that the pump flow was calibrated and that sampling was conducted after adequate cleaning and, where required, aggressive disturbance. Because the 0.012 result is close to the limit, the contractor should also consider whether the fibers are asbestos or other fibers; PCM counts all fibers and cannot identify asbestos. The correct response is to reclean the suite, HEPA-vacuum and wet-wipe surfaces, then repeat clearance sampling. The area should not be released for occupancy until every clearance sample meets the criterion and a visual inspection shows no debris or dust.
2. Evaluate the waste handling and transport deficiencies and describe what must be corrected.
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The waste handling is noncompliant. Asbestos-containing tile and debris must be wetted, packaged in leak-tight containers, and labeled with the required asbestos warning and generator information. Fifty-five unlabeled bags in an open dumpster do not meet that requirement, and torn bags can release fibers and contaminate the dumpster and surrounding area. The contractor should stop adding waste, inspect and repackage torn bags, clean the dumpster area with wet methods and HEPA vacuuming if contaminated, and use closed, labeled containers. The waste must be transported to a landfill permitted to accept asbestos waste, and the shipment should be accompanied by a waste shipment record or manifest identifying the generator, transporter, and disposal site. The landfill's permit alone does not satisfy the generator's labeling and recordkeeping duties. The contractor should also retain disposal receipts and maintain worker training and respiratory protection records for the job. Because the waste is already outside, the contractor should determine whether visible emissions occurred and document corrective actions.