Friday, August 22, 2008
Last year, the Environmental Protection Agency (EPA) responded to a question by the New York State Department of Labor (NYSDOL) regarding the minimum number of bulk samples required for suspect asbestos containing miscellaneous materials (see our blog post dated 6/24/08). This clarification determined that the minimum number of samples is two (2) samples of each suspect homogeneous miscellaneous materials. This clarification was determined based on a review of the EPA's Asbestos Hazard Emergency Response Act (AHERA) section 763.86 -Sampling. This section of the AHERA regulation is used by asbestos inspectors to determine the number of samples to take of each homogeneous area.
The core of all asbestos inspections is the determination of the type of material (surfacing material, thermal system insulation, or miscellaneous material) and whether the materials are homogeneous. Homogeneous area is defined as a type of material that is uniform in color and texture (as per 763.83). Once the type of material is determined and the material is classified as a homogeneous area, then the number of samples for each area is determined.
If the suspect asbestos material is a surfacing material, the square feet of the homogeneous area is determined which provides the inspector with the minimum number of samples that shall be taken. If the homogeneous area is less than 1,000 square feet, the inspector shall take 3 samples. If the area is between 1,000 and 5,000 square feet, the inspector shall take 5 samples. When the are is over 5,000 square feet, the inspector shall take 7 samples. This is sometimes known in the industry as the 3-5-7 rule.
Should the suspect asbestos material be classified as thermal system insulation then the inspector must determine if the material is a homogeneous area, a patch material, or a cement or plaster used on fittings (tees, elbows, or valves). Homogeneous areas of thermal system insulations shall require 3 samples, while each homogeneous area of patch material less than 6 linear feet or 6 square feet shall require only 1 sample. Cement or plaster used on fittings shall be sampled based on each insulated mechanical system (hot water, cold water, steam, chilled water, etc.) and shall require a minimum of 2 samples be taken.
Some general rules to remember when taking bulk samples, is sampling should be taken in a randomly distributed manner. Bulk samples cannot be composited and shall be submitted to laboratories accredited by the National Bureau of Standards. Asbestos Inspectors determine a homogeneous area contains asbestos when one of the required number of samples contains asbestos in the amount greater than 1%. Should all the required samples taken in an homogeneous area result in asbestos amounts less than or equal to 1%, then the area does not contain asbestos. Asbestos Inspectors should remember these rules when they sample.