Asbestos in Crawl Spaces Asbestos abatement in crawl spaces forces professionals to enter uncomfortable environments that might involve contact with pests, open sewer lines, and enclosed spaces. The majority of crawl spaces also have only a dirt floor. Unlike occupied areas of a building, crawl spaces are entered only infrequently, generally by maintenance workers, for short periods of time. One reason individuals might need to enter a building’s crawl space is to maintain or install communications hardware, such as a network of communications wiring.
Crawl Space Abatement The abatement of crawl spaces generally includes the removal of thermal system insulation from ducts and pipes, fallen or detached pieces of insulation, and contaminated dirt. However, a thorough inspection of the crawl space, a project design survey, is essential to locating and determining the extent of asbestos contamination. This survey is then used to prepare for the actual process of removal. Abatement of crawl spaces should be limited to actual locations where asbestos was placed, including around piping and ducts, under areas that held asbestos where it might have fallen, and in areas where previous movement and disruption may have occurred and spread the material. Sometimes all areas of a crawl space will not require attention from the abatement crew, especially if the asbestos has not been damaged or disturbed. However, this determination should be made by the project designer, who consults the contract documents and drawings to determine the limits of abatement. An ongoing controversy of crawl space abatement revolves around how deep workers must dig to remove asbestos-containing materials from dirt floors. In most cases, asbestos does not penetrate deeply into tightly packed earth, though asbestos filled into trenches or carried by water into porous soil or fissures will justify deeper digging.
Crawl Space Characteristic Considerations Abatement in a crawl space deserves additional considerations that occupied areas might not require. These considerations might include the wall surfaces, which can be the rough, difficult-to-clean surfaces of brick or block construction, and the uneven dirt floor. However, not all considerations will necessarily make abatement of these areas more difficult. For example, the need to scrape a ceiling or remove fireproofing will likely not arise. In addition, water control will be easier when removing duct and pipe insulation, as only walls within splashing distance require protection. Nevertheless, OSHA requires that crawl spaces be under negative pressure because this is Class I work. Additionally, a full decontamination facility and load-out for removed material and dirt must be present. Standards for acceptance of crawl space abatement remain the same as any other area: no visible residue and no unremoved material may be present. After inspection approval, a sealer is applied to abated surfaces other than a dirt floor.
Removing Asbestos from Dirt Floors After the sealant has been applied and protective plastics have been removed, the contaminated dirt flooring may be manually cleaned using hand implements such as shovels and rakes. Vacuum-assisted devices are also often utilized. The contaminated dirt is then placed in sealed drums and bags for removal. Although some specifications require that a minimal amount of dirt be removed from a crawl space, such a requirement is often ill-advised because it encourages removal of dirt rather than actual asbestos. Furthermore, it is difficult to measure how deep an abatement team has dug down, while asbestos rarely penetrates more than a half inch below the surface. To check for the complete removal of asbestos from a crawl space floor, abatement teams must examine the floor closely with a strong light. A small tool should be used to sift through the dirt to ensure that no asbestos-containing materials remain. If further asbestos materials are found, the contaminated dirt is removed, not just the asbestos fragments. In fact, all debris is considered asbestos except for obvious garbage. If widespread contamination or asbestos impacted in the dirt flooring remains, the supervisor will order the crawl space recleaned. A crawl space is considered completely clean after it passes the inspection of the dirt floor. Sometimes a sealant can also be applied to an uneven floor. Final cleanup criteria include the absence of debris on the dirt surface, the removal of all contaminated dirt down to the hardpan, and no visible debris impacted into the hardpan. Final air samples are also taken for clearance, which is done during the final inspection. This simulates typical activity levels in the area and allows crews to see the likely asbestos fiber exposure risks to future visitors to these areas.