THE COHEN GROUP
  Environmental Health & Safety Consulting Services

The Cohen Group Newsletter - Volume 7  Issue 1, Article 2.  January, 2005

Naturally Occurring Asbestos in California
By Joy E. Fleming, MPH

 Natural occurrences of asbestos are likely to be encountered in California during excavation and road work in areas with ultramafic and serpentine rock. Sometimes the geologic conditions are right for the formation of chrysotile asbestos or tremolite-actinolite asbestos in bodies of the rock or along their boundaries. A registered geologist can identify ultramafic and serpentine rock and collect bulk samples of suspect rock for analysis.

The California Air Resources Board (ARB) has adopted two Airborne Toxic Control Measures (ATCMs) for asbestos; one that prohibits the use of serpentine or ultramafic rock for unpaved surfacing and one that requires controls on dust emissions from construction, grading, and surface mining in areas with these rocks. There may also be additional or more stringent requirements concerning asbestos adopted by each local Air Pollution Control District (APCD) or Air Quality Management District (AQMD).

As of November 13, 2001, each APCD and AQMD must implement or enforce the requirements of the Asbestos ATCM for Surfacing Applications. This ATCM (17 CCR § 93106) prohibits a person to use, apply, sell, supply, or offer for sale or supply any restricted materials for surfacing, unless it has been tested using an approved asbestos bulk test method and determined to have an asbestos content that is less than 0.25 percent.

Restricted materials are defined as; 1) aggregate material extracted from an area defined as a geographic ultramafic rock unit, 2) aggregate material tested or identified to have an asbestos content greater than 0.25 percent, or 3) any mixture of aggregate material that contains ten percent or more of any of the materials previously mentioned.

As of November 19, 2002, each APCD and AQMD must also implement or enforce the requirements of the Asbestos ATCM for Construction, Grading, Quarrying, and Surface Mining Operations. The ATCM (17 CCR § 93105) requires road construction and maintenance activities, construction and grading operations, and quarrying and surface mining operations in areas where naturally-occurring asbestos is likely to be found to employ the best available dust mitigation measures. The regulation applies to any portion of the area being disturbed in a geographic ultramafic rock unit or determined to contain naturally-occurring asbestos, serpentine, or ultramafic rock. The ATCM also applies if ultramafic rock, serpentine, or asbestos is discovered during any operation or activity.

Road construction and maintenance operations must use specified dust control measures and prevent visible emissions crossing the project boundaries. For construction and grading projects that will disturb one acre or less, the regulation requires several specific actions to minimize emissions of dust such as vehicle speed limitations, application of water prior to and during the ground disturbance, keeping storage piles wet or covered, and track-out prevention and removal. Construction projects that will disturb more than one acre must prepare and obtain district approval for a written asbestos dust mitigation plan.

Regardless of the size of the disturbance, activities must not result in emissions that are visible crossing the property line. Where a dust mitigation plan is required, the local APCD or AQMD may require an air monitoring component.

Even if the APCD or AQMD does not require air monitoring, employee exposure monitoring may be required by Cal-OSHA if the disturbance of asbestos-containing materials may produce exposures at or above 0.1 fibers per cubic centimeter. Excavation and construction activities which may involve exposures to asbestos as a natural constituent (except where related to asbestos mining or milling activities) are regulated under Title 8 CCR Section 1529.

Feel free to call us if you have questions concerning compliance with the myriad of agency asbestos standards.