PUBLIC HEALTH ASSESSMENT
MATHER AIR FORCE BASE
MATHER, SACRAMENTO COUNTY, CALIFORNIA
On the basis of its evaluation of available environmental information, ATSDR concluded that the exposure situations at Mather pose no apparent public health hazards. Conclusions regarding media and site-specific exposures are as follows:
No apparent public health hazards are associated with past exposures to VOCs and perchlorate above comparison values in on-base supply systems, off-base community supply systems, and off-base private wells. Exposures to on-base workers and on and off-base residents contacting contaminants in drinking water were evaluated using conservative, site-specific exposure assumptions. In each instance, no adverse health effects to adults or children were identified from past exposures.
The USAF and community water suppliers have closed contaminated wells, installed treatment systems, and currently monitor active wells regularly. Regular monitoring includes collecting quarterly samples from on-base supply systems, off-base community supply systems, and private wells to the west and south and analyzing the samples for VOCs and/or perchlorate. The USAF also connected homes and businesses with private wells to the west to the community supply system. These measures prevent current and future exposures to contaminants that may pose potential public health hazards.
No apparent public health hazards to on-base workers and recreational users, including members of the general public and on-base residents, are associated with past exposures to contaminants above comparison values in surface soil. These comparison values are derived assuming daily contact with contaminated soils, and actual exposures to workers and recreational users were expected to be much less frequent, resulting in a lower exposure level.
On-base residents were not exposed to contaminants in surface soil in the on-base military housing area because no areas of surface soil contamination were found in this area. Residents in the transitional housing units were not exposed to contaminants in surface soil because IRP sites located near the units were remediated before the units opened in 1996.
The USAF is conducting remedial actions, with oversight by USEPA and CALEPA, to prevent future exposures to contaminants at levels of health concern in surface soil.
No apparent public health hazards to on-base workers, residents, and recreational users are associated with past exposures to contaminants in surface water and sediment. No comparison values are available for surface water and sediment, therefore, contaminant concentrations were compared to drinking water and surface soil comparison values, respectively.
Exposure to contaminants in surface water and sediment may have occurred during stream and ditch maintenance or recreational use of streams and ditches, which would be much less frequent than the daily exposure assumed by the drinking water and surface soil comparison values.
To prevent current and future exposures to contaminants at levels of health concern in surface water and sediment, the USAF is completing remedial actions with oversight by USEPA and CALEPA.
The Public Health Action Plan (PHAP) for Mather contains a description of actions taken and those to be taken by ATSDR, the USAF, USEPA, and CUCC subsequent to the completion of this PHA. The purpose of the PHAP is to ensure that this PHA not only identifies potential and ongoing public health hazards, but provides a plan of action designed to mitigate and prevent adverse human health effects resulting from exposure to hazardous substances in the environment. The public health actions that are completed, ongoing or planned, and recommended are listed below.
- The USAF identified potential hazardous substance release sites (grouped in six OUs) during base investigations.
- The USAF, USEPA, and CALEPA have completed investigations and signed RODs for five of the six OUs: the AC&W, Landfill, Soil, Groundwater, and Basewide OUs.
- Remedial actions to address soil, surface water, and sediment contamination have been completed at some sites within the AC&W, Landfill, Soil, Basewide, and Supplemental Basewide OUs. Remedial actions have included landfill capping, UST removals, soil and sediment excavation and treatment, and on- and off-base disposal. Institutional controls and/or deed restrictions are in place at sites where contamination is currently buried and inaccessible to the public and other sites with proposed land use that would limit public access (e.g., landfills).
- The USAF, with oversight by USEPA and CALEPA, prepared an off-base water supply contingency plan that outlines monitoring requirements for tracking contaminant migration toward drinking water supply wells. This plan also contains provisions for providing alternate water supplies or installing treatment systems if a well is affected by contamination from Mather.
- The USAF is conducting investigations and identifying potential remedial actions for sites in the Supplemental Basewide OU. Remedial actions will be selected considering the proposed future land use of a site.
- At some sites within the Landfill, Soil, and Basewide OUs, the USAF is conducting ongoing remedial actions. The landfills are vented and regularly monitored for methane migration under RCRA and CALEPA regulations. Gas venting is ongoing at Landfill sites 3 and 4 to prevent explosive levels of methane from migrating off base in subsurface soil. Soil vapor extraction systems and in-situ treatment systems are in operation at several sites to remove contaminants from soil.
- To implement the remedial actions selected in the AC&W and Groundwater OU RODs, the USAF regularly samples nearly 400 monitoring wells located on and off base to the south and west to track plume migration. Monitoring wells may be sampled quarterly, biannually, or annually, as outlined in the Groundwater Monitoring Program Evaluation Report. Samples are analyzed for VOCs and/or perchlorate. Groundwater treatment systems have been installed and have begun operating to treat contaminants in the AC&W, Main Base and SAC Industrial Area, and Site 7 groundwater plumes. Additional extraction wells will be installed to treat the Site 7 groundwater plume after gravel mining to the south is completed. Since contaminants within the Northeast groundwater plume are only slightly above drinking water standards, monitoring was selected as the most appropriate remedial action. Contaminants within this plume, however, would likely be captured by the Main Base and SAC Industrial Area groundwater plume treatment system because the Northeast groundwater plume merges with this plume.
- The USAF and public water suppliers regularly monitor water supply wells to ensure that the water supply is free of contamination at levels of health concern. Regular monitoring includes collecting samples from on-base supply systems, off-base community supply systems, and off-base private wells to the west and south and analyzing the samples for VOCs and/or perchlorate.
- Members of the community and the USAF participate in regularly scheduled Restoration Advisory Board meetings. These meetings serve as a forum for communication of ongoing and planned activities at Mather to the community and for communication of community concerns to Mather personnel.
- If new information from site investigations identifies contaminants in site media above ATSDR's health-based comparison values, ATSDR will assess contaminant data and exposure situations to identify if any public health hazards exist. ATSDR will also re-evaluate the potential for public health hazards if changes in proposed land use, remedial activities, or risk management actions (e.g., institutional controls) may lead to future exposures.
Air Force Base Conversion Agency (AFBCA). 1997. Final Basewide Operable Unit Focused Feasibility Study Report For Mather Air Force Base, California, Volume II. April 1997.
AFBCA. 1998. Final Mather AFB Off-base Water Supply Contingency Plan. February 9, 1998.
AFBCA. 1999. Mather Air Force Base Five-Year Review of Remedial Actions under the Comprehensive Environmental Response, Compensation, and Liability Act (Draft). February 9, 1999.
Air Force Center for Environmental Excellence (AFCEE). 1996. Final Comprehensive Baseline Risk Assessment for Mather Air Force Base, California, Volume II. October 16, 1996.
ATSDR. 1989. Preliminary Health Assessment for Mather Air Force Base, California. April 17, 1989.
ATSDR. 1994. Toxicological Profile for Carbon Tetrachloride (update). ATSDR, U.S. Department of Health and Human Services. May 1994.
ATSDR. 1998. Perchlorate Contamination in the Mather Air Force Base Water Service Area, Aerojet General Corporation, Rancho Cordova, Sacramento County, California. May 6, 1998.
Bureau of Census. 1991. Census of Population and Housing, 1990; Summary Tape File 1A (California) [machine-readable data files]. 1991.
California Department of Health Services (CDHS). 1997. Perchlorate in Drinking Water. Fact Sheet. May 1997.
CDHS, 1999. Standards for Perchlorate in Drinking Water. http://www.dhs.cahwnet.gov/ps/ddwem/chemicals/perchl/perchl_standards.htm. Downloaded November 18, 1999.
California Economic Diversification and Revitalization (CEDAR). 1999. California Military Base Closures: Current Status of Reuse Efforts, Mather Air Force Base. Downloaded April 30, 1999. http://www.cedar.ca.gov/military/current_reuse/mather.htm#mather_anchor.
CH2MHill. 1982. Installation Restoration Program Records Search Report. June 1982.
Fricke. 2000. Correspondence from Rodney Fricke, Environmental Manager, Aeroject to the Agency for Toxic Substance and Disease Registry. Comments to the Public Health Assessment for Mather Air Force Base, Mather, Sacramento County California. August 28, 2000.
Gutierrez-Palmenberg, Inc. 1997. U.S. Air Force Installation Restoration Program Community Relations Plan (Draft). April 1997.
Gutierrez-Palmenberg, Inc. 1999. U.S. Air Force Installation Restoration Program Community Relations Plan. June 1999.
Hughes. 1999. Personal communication with William Hughes, contractor for the Air Force Base Conversion Agency at Mather Air Force Base. July 29, 1999 and November 19, 1999.
Hughes. 2000. Personal communication with William Hughes, contractor for the Air Force Base Conversion Agency at Mather Air Force Base. March 20, 2000, August 28, 2000, and September 9, 2000.
Houston. 1985. Correspondence from Colonel Bruce R. Houston, USAF Staff Judge Advocate to Major McLauthlin, USAF/JACC. Request for Use of Defense Environmental Restoration Funds for Bottled Water. May 23, 1985.
IT Corporation. 1993a. Final Remedial Investigation Report for Group 2 Sites, Mather Air Force Base, California, Volume 1. April 1993.
IT Corporation. 1993b. Final Technical Memorandum for Group 3 Sites, Mather Air Force Base, California, Volume IV. September 1993.
IT Corporation. 1996. Installation Restoration Program, Final Additional Site Characterization and Final Basewide Operable Unit Remedial Investigation Report for Mather Air Force Base, California, Volume 1: Text, Tables, and Figures. September 5, 1996.
IT Corporation. 1997. Air Force Installation Restoration Program, Final Site Characterization Report for IRP Sites 86 and 87, Mather Air Force Base, California. February 1997.
Lamm S., Doemland M. 1999. Has Perchlorate in Drinking Water Increased the Rate of Congenital Hypothyroidism? J Occup Environ Med 41(5): 409-11. May 1999.
McDonald. 2000. Personal communication with Alex McDonald, Aerojet Remedial Project Manager for the Regional Water Quality Control Board. March 28, 2000.
Montgomery Watson. 1997. Draft Final 1996 Basewide Groundwater Monitoring Report, Mather Air Force Base, Sacramento, California. July 1997.
Montgomery Watson. 1998a. Draft Final Annual 1997 Basewide Groundwater Monitoring Report, Mather Air Force Base, Sacramento, California. July 1998.
Montgomery Watson. 1998b. Draft Final Project Definition Investigation Report for Surface Soil and Sediment Sites 10C, 69, 80, 81, and 88, Mather Air Force Base, Sacramento, California. July 1998.
Montgomery Watson. 1998c. Draft Final Groundwater Monitoring Program Evaluation Report, Mather Air Force Base, Sacramento, California. December 1998.
Montgomery Watson. 1999a. Draft Annual and 4th Quarter 1998 Basewide Groundwater Monitoring Report, Mather Air Force Base, Sacramento, California. March 1999.
Montgomery Watson. 1999b. Second Quarter 1999 Basewide Groundwater Monitoring Report, Mather Air Force Base, Sacramento, California. September 1999.
Smith. 1993a. Correspondence from Charles Smith, Remedial Project Manager to AFBCA/NW. Recommendation to Initiate Sampling Program for Off-base Water Supply Wells. September 8, 1993.
Smith. 1993b. Correspondence from Charles Smith, Remedial Project Manager to Capt. Evenson, AFCEE/ESB. Sampling Program for Off-base Water Supply Wells. November 3, 1993
Smith. 1994. Correspondence from Charles Smith, Remedial Project Manager to Capt. Miller, AFCEE/ERB. Sampling Program for Off-base Water Supply Wells. June 13, 1994.
Spath. 1997. Correspondence from David P. Spath, California Department of Health Services to Anthony C. Wong, Mather Air Force Base. Regarding the California Department of Health Services May 1997 Perchlorate Standard. May 22, 1997.
Taylor. 1999. Personal communication with James Taylor, former Mather Remedial Project Manager for the Regional Water Quality Control Board. December 20, 1999 and March 28, 2000.
USAF. 1993. Superfund Record of Decision: Aircraft Control and Warning Site. October 1993.
USAF. 1994a. BRAC Cleanup Plan, Mather Air Force Base, Rancho Cordova, California. April 1994.
USAF. 1994b. Mather Air Force Base, Briefing to ATSDR. May 5, 1994.
USAF. 1995. Superfund Record of Decision: Landfill Operable Unit Sites (final). July 1995.
USAF. 1996. Superfund Record of Decision: Soil Operable Unit Sites and Groundwater Operable Unit Plumes (final). April 29, 1996.
USAF. 1997. Flyer - Agency for Toxic Substances and Disease Control - First Priority - Human Health. Faxed August 19, 1997.
USAF. 1998. Comprehensive Environmental Response, Compensation, and Liability Act of 1980 Record of Decision, Basewide Operable Unit Sites, Mather Air Force Base, Sacramento County, California (Final). August 24, 1998.
USAF. 1999. Information provided by USAF representatives during the ATSDR Site Visit. May 10 to 13, 1999.
U.S. Environmental Protection Agency (USEPA). 1999. National Center for Environmental Assessment. Perchlorate Environmental Contamination: Toxicological Review and Risk Characterization Based on Emerging Information (Abstract). http://www.epa.gov/ncea/perch.htm. Downloaded November 19, 1999.
Wong. 1999. Correspondence from Anthony C. Wong, Mather Air Force Base. Regarding Solicitation of Concurrence with Applicable or Relevant and Appropriate Requirements. January 6, 1999.