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Contact Region 9

Pacific Southwest, Region 9

Serving: Arizona, California, Hawaii, Nevada, Pacific Islands, Tribal Nations

Naturally Occurring Asbestos

El Dorado Hills

Multimedia Exposure Assessment
Preliminary Assessment and Site Inspection Report Interim Final

El Dorado Hills Quick Finder
El Dorado Assessment Home 1.0 Introduction 2.0 Apparent Problem 3.0 Site Location, Description & History 4.0 Regulatory Involvement 5.0 Summary of Investigative Efforts 6.0 Hazard Ranking System Factors 7.0 Emergency Response Considerations 8.0 Summary Appendices References Acronyms Definitions Appendices & References
(in order of use on this page)
  • f/cc
    fibers per cubic centimeter
  • s/cc
    structures per cubic centimeter

4.0 Regulatory Involvement

The CARB has conducted air monitoring in several locations in California to determine levels of asbestos in air at selected sites. In April 1999, the CARB measured ambient asbestos concentrations in air at seven monitoring locations at and near Silva Valley Elementary School. Of the 20 samples collected at the school, four of the samples contained detectable levels of asbestos; the highest level detected (in two of the samples) was 0.0019 fibers per cubic centimeter (f/cc).

While there has been no other regulatory involvement to date related to the locations that are the subject of the El Dorado Hills Naturally Occurring Exposure Multimedia Assessment, the El Dorado Union High School District has been working with several agencies at the Federal, State and local levels to address the ex­posed asbestos at the nearby Oak Ridge High School. Mitigation actions undertaken by the school district are described in the El Dorado Union High School District Oak Ridge High School Naturally Occurring Asbestos (NOA) Operations and Maintenance (O&M) Plan, dated December 2003, prepared by MACTEC Federal Programs.

The CARB conducted air sampling in June and July 2003 to assess the type and quantity of asbestos fibers released to ambient air during mitigation activities at the soccer fields. The CARB sampling documented the presence of asbestos in ambient air samples collected during mitigation activities, with a maximum asbestos level recorded in air of 0.0039 structures per cubic centimeter (s/cc) and an average concentration at the mitigation fence line of 0.001 s/cc. A complete description of the CARB sampling locations, methodology and findings is available in the November 6, 2003, CARB report Sampling for Airborne Naturally Occurring Asbestos at Oak Ridge High School June 2003.

Due to citizens' concerns about asbestos on the Oak Ridge High School campus, the U.S. EPA and START conducted an assessment of surficial soil at the high school in November 2003 to determine whether additional mitigation efforts were required in areas other than those related to the soccer fields. During the assessment exposed soils throughout the campus were sampled, particularly those areas where observed or expected student or public traffic could disturb asbestos-containing soil or rock. Sampling documented that asbestos was present in exposed soils throughout the campus ranging from less than 0.0001 to 8.8 per­cent by weight. U.S. EPA subsequently performed remediation at Oak Ridge High School by covering exposed soil with landscaping, concrete, or pavement.

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