Soil Encapsulant

Question: My client has a utility tunnel with a soil floor. Due to previous (incorrect) abatement, there is a good deal of asbestos waste mixed with the soil. How can this be made safe and are licensed personnel required?


The tunnel is 8 feet wide and several hundred feet long and testing has shown that it is heavily contaminated with asbestos. The state has agreed that it is not necessary at present to remove it, and the client would like to cover it with concrete.


The best procedure would involve two major steps:

  1. Bind the soil together with a suitable encapsulant using airless spray equipment. Both Indian and the federal rules require that encapsulation inside a building must be done by properly licensed/accredited personnel. However, this job is not technically difficult and should be manageable by a competent contractor following the manufacturer's instructions. Worker protection against respiratory hazards are important, though, since I doubt that the ventilation is adequate to deal with spraying a product into the air into a space that is probably not ventilated too well; consider using local exhaust ventilation to remove aerosol droplets from the area. Because more than 160 square feet of regulated asbestos-containing material is involved, proper notice must be given to state or local authorities at least 10 working days (2 weeks) before the work begins. Soil-contaminated wastes (such as disposable tools and protective clothing) generated during this phase of the work are asbestos-wastes and must be disposed of accordingly. However, since an asbestos contractor is performing the work, this should not be problematic.
  2. Following the encapsulant drying time recommended by the manufacturer, the concrete work can begin. Since the soil has now been rendered nonfriable, this work can be done by an experienced cement contractor. To minimize the damage to the soil during the work, you may want to use a soil protection sled illustrated below. The laborers would stand on this surface when working the wet concrete and would move it after each section is laid and smoothed by lifting one end with the rope and dragging past to the next section of pour. Since this is a large-scale maintenance project which should not disturb asbestos, OSHA requirements for this work would be:
    • Perform initial monitoring to ensure that the preliminary negative exposure assessment is confirmed.
    • Perform 2-hour awareness training for persons performing the work.
    • Have a competent person with a minimum of 16-hours of training establish the safety requirements and check the start of the work to ensure that proper protections are in place, including work practices, training of employees, etc. Note: The project designer can be designated by the contractor to perform this function. The competent person does not need to be present throughout the job but must be available at reasonable times to answer employee questions and must check the job sometime during the work to ensure that the engineering controls and work practices specified are still adequate to protect workers.
    • Utilize the three required work practices, namely, wet methods (including wetting of wastes), HEPA vacuums (for example, for cleaning workers' clothing and booties before exiting the area) and prompt disposal of asbestos-contaminated wastes (such as booties, rags, the sled, etc.) in sealed containers which are properly labeled when in the workplace.
    • The workers should wear disposable booties (to keep from taking any soil-asbestos mixture into their vehicles, etc.). This is not required by OSHA for this particular task.
    • Respiratory protection should not be required but the possibility of non-asbestos hazards (other air contaminants or low oxygen) should be considered and adequate ventilation should be ensured.
    • Provide booties to prevent shoe contamination and waste bags, labels, and plastic sheeting for waste disposal.
    • Note: The wastes generated during this phase of the work are not asbestos wastes and can be handled as ordinary municipal solid waste or construction debris, as appropriate.
    • Use the three required methods: wet methods, HEPA vacuums (if needed for removing soil from clothing, for example), and prompt waste disposal (for booties and any other materials possibly contaminated with the soil).
  3. After the work is completed the presence of this material must be documented and when the building is demolished the top layer of soil under the concrete must be disposed of properly as asbestos waste. Also, because this is a maintenance area, a sign must be posted at all entrances informing entrants that there is asbestos in the soil under the floor. It would probably be advisable (although not required) to note the demolition requirements on the soil so that the information is available at the time of actual demolition.

Figure. Soil protection sled.


The Law.

  1. EPA NESHAP and corresponding Indiana NESHAP. These regulations require that any renovation work (which this clearly is) be inspected for the presence of asbestos-containing material (ACM) and if there is more than 160 SF of regulated ACM, then the relevant authority must be notified on the appropriate form at least 10 working days before work begins. (In Indianapolis the corresponding rule is activated at 15 SF of regulated ACM.) It also requires that all wastes containing or contaminated by regulated ACM must be sent to a state-approved landfill on the appropriate waste disposal notification form. The building owner is liable if this notice is not filed.
  2. EPA Model Accreditation Plan and Indiana Asbestos Licensing Rule. These regulations require that all persons performing encapsulation, enclosure, or removal of friable ACM be licensed by the State of Indiana. Thus, the contractor, supervisor, and workers performing the soil encapsulation must be licensed. The building owner is liable if the contractor fails to use persons with the appropriate licenses.
  3. OSHA Construction Industry Asbestos Standard. This standard requires that all persons working with asbestos (whether or not it is friable) notified by the building owner (in the bid process for contractors) of the location, identity, and amount of asbestos. OSHA requires that the employer whose employees are performing the work designate a competent person to ensure that the likely exposure be properly determined (acual monitoring would appear to be required on this job), that the project be designed with employee safety in mind and be conducted in a way that ensures that a safe and healthy workplace was maintained. OSHA also requires that the employer provide proper training. Since this work involves maintenance and repair of the facility (and not asbestos removal), the level of training depends on the expected exposure.
    • It is likely that the initial work could be done by 16-hour operations & maintenance personnel, but since the EPA requires licensing, that rule governs.
    • Once the soil is encapsulated, no actual disturbance of asbestos is expected, so persons with a 2-hour awareness class could conduct the application of a concrete layer

The Issues: The key issues -- licensing/accreditation/training, NESHAP notification, worker protection, waste disposal -- have been addressed in the recommendations and legal sections above.

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