|Image of raw asbestos, courtesy of Envirotest Labs|
For all the romance of historic building preservation, one always has to face the reality that, in old buildings, there’s always the potential for finding hazardous materials which will need to be removed by a qualified contractor. We recently hired Envirotest Laboratories, Inc. to test suspect materials at the Alvah Kittredge House for asbestos and to assist us through the abatement process. For those unfamiliar with this process, here is a primer.
The first step entailed collecting samples of any materials that might contain 1% or more of asbestos, which were many, as the house contains a jumble of finishes that had been installed in its over 150 years of use. Typical materials to test include floor and ceiling tiles, pipe and furnace insulation, window putty and flooring mastic, but even plaster from the late 1800s sometimes contained asbestos.
Regulations controlling asbestos were enacted in 1985, but at that time laws allowed up to 5% of the substance to be added to materials, so manufacturers continued to use it as an inexpensive bonding and strengthening material. In 1992 regulations were modified to lower the permissible amount to less than 1%, and manufacturers finally stopped using it as an additive.
|The drums of abated material removed from the Kittredge House|
The next step was for Envirotest to develop an abatement plan which was approved by the Department of Environmental Protection. This plan was used to solicit contractor bids after a walk-through on the site. E & F Environmental Services was chosen and the work began.
The first day of remediation was committed to carefully setting up the site to ensure all regulations are followed and no asbestos contaminants were spread to other areas. All doors, windows and openings to the containment area were sealed, and the abatement area was set up with a negative air machine which filters exhaust air from this area through HEPA filters at a rate of four air changes per hour. A decontamination facility was set up that allows workers to enter and leave the abatement area without spreading contaminants. This consisted of three areas to pass through: the “dirty room” (in this case the stairwell) where workers removed 2 layers of Tyvek suiting; the “shower room” (a portable station the size of a phone booth) where workers used soap and water to wash hands, faces, and any exposed skin (dirty water is then sucked into a wet vac and disposed of as a contaminant); and finally the “clean room,” where workers left their respirators before exiting the area. Each of these areas is isolated from the other with double layers of heavy plastic flaps. All abated materials were placed in drums that were lined with bags; the bagged materials were wet down to prevent dust from escaping, then sealed and removed from the site.
|Image of equipment utilized during abatement|
We are grateful to the workers who completed the abatement; this work is grueling, particularly in summer in a hot, stuffy environment where workers are wearing one layer of street clothes and two layers of Tyvek suiting and breathing through respirators. We are also thankful for the assistance of Envirotest Laboratories for guiding us through this complicated process.