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Draft Preliminary Site Evaluation
Santa Susana Field Laboratory (SSFL)
Ventura County, California

Conclusions and Recommendations

In this preliminary evaluation of available data and information, ATSDR has not identified an apparent public health hazard to the surrounding communities because people have not been, and are currently not being exposed to chemicals and radionuclides from the site at levels that are likely to result in adverse health effects.

Air Pathway

Available environmental data indicate that chemicals and radionuclides have been released to air during rocket engine testing and waste handling and disposal activities at the SSFL. Quantitative air monitoring data and verified site-specific meteorological data are not available. Releases in the past were probably higher than at present. Given that the nearest communities are located more than one half mile from any onsite release sources, it appears unlikely that onsite releases would migrate to offsite areas at levels that would pose a health hazard to the surrounding community.

Ground and Surface Water Pathway

Ground water under the site is contaminated by trichloroethylene (TCE) that has migrated offsite of the northwestern and northeastern facility boundaries. Contamination was first recognized in the 1980s and concentrations of TCE, and its degradation products, have declined over time. The majority of the local water supply is provided by purveyors who obtain water from surface water sources distant from the SSFL. These purveyors have supplemental water supply wells that are located more than two miles from the SSFL. Some privately-owned water wells are located in the Santa Susana Knolls and unincorporated areas of Simi Valley. Available data and information provide no indication that municipal and privately-owned water wells have been adversely impacted by chemicals or radionuclides from the SSFL. As a result of the ongoing ground water remediation at the SSFL site, it is unlikely that there will be future exposure to contaminated ground water. Because the potential for deep fracture flow from the site has not been adequately characterized, there is a potential for substances in ground water to discharge at springs or down-gradient water wells along the margins of Simi and San Fernando Valleys.

Soil and Sediment Pathway

Available data and information indicate that chemical and radionuclide releases to soil and sediment have occurred at the SSFL. One important source of releases is the Former Sodium Disposal Facility located in Area IV. There has been limited soil and sediment migration of chemicals and radionuclides from the Disposal Area to offsite areas north of the facility boundary. Concentrations are highest close to the facility boundary and decrease rapidly with increasing distance from the property boundary. Because the area surrounding the SSFL is hilly and rugged, it is not easily accessible to persons in the nearby community. Any human exposure to these maximum offsite concentrations is not likely to result in adverse human health effects. Based on available data and information, there is no indication that offsite residential areas, including the Brandeis-Bardin Institute, Santa Monica Mountains Conservancy, and Bell Canyon, have been adversely impacted by chemicals and radionculides from the SSFL. Therefore, there is no apparent likelihood for human exposure to chemicals and radionuclides in soil and sediment in these offsite areas. In response to comments made by the Las Vegas EPA office on the sampling techniques used to characterize radionuclides in Area IV of the facility, further characterization of Area IV radionuclides is being proposed by EPA and the Department of Energy.

Recommendations

ATSDR acknowledges that this report is a preliminary assessment of the potential for human exposure and public health hazard posed by the SSFL. On the basis of our preliminary conclusions, we make the following recommendations:

  • A more in-depth evaluation of exposure pathways that addresses past, current, and future exposure to chemicals and radionuclides from the SSFL should be conducted to improve the assessment of potential offsite exposures and public health implications associated with this site. Such an assessment must be facilitated through community outreach and participation and must include health education activities. We further recommend that this assessment address the following related issues:
    • More in-depth evaluation of airborne chemical releases from SSFL operations, including air dispersion modeling of past accidents and disposal activities, and compilation and use of a consistent, site-specific meteorological data set to improve the assessment of past exposures to these substances.
    • Development of a regional hydrogeological flow model and additional monitoring at down-gradient springs or seeps in Simi Valley and Santa Susana Knolls to evaluate the potential for deep fracture flow and potential future exposure. Also, even though it may not be related to SSFL, additional source characterization of the perchlorate detection in Simi Valley should be conducted.
    • Additional radiological characterization of Area IV with more sensitive instrumentation and appropriate grid spacing to assure a lower detection limit.


  • A re-analysis of the cancer registry data including additional years of newly available cancer data and updated demographic information should be conducted to see if the apparent increase in the incidence rates of bladder and lung cancers persist. A more in-depth evaluation of cancer data should be conducted that addresses environmental exposures from the SSFL, possible confounding exposures from other nearby contaminant release sources, and residential histories.

References

ABB Environmental Services, Inc., 1992. Final Report: Air Sampling for Chemical Analysis from Rocket Engine Test Firing Plumes at the Rocketdyne Santa Susana Field Laboratory. Submitted to Rocketdyne Division, Rockwell International, Corporation, Canoga Park CA, June 12, 1992.

ATSDR, 1997a. Toxicological Profile for Hydrazines. Agency for Toxic Substances and Disease Registry, Atlanta GA, September 1997.

ATSDR, 1997b. Toxicological Profile for Polychlorinated Biphenyls (Update). Agency for Toxic Substances and Disease Registry, Atlanta GA, September 1997.

ATSDR, 1998. Toxicological Profile for Chlorinated Dibenzo-p-Dioxins (Update). Agency for Toxic Substances and Disease Registry, Atlanta GA, December, 1998.

CDHS, 1990. Cancer incidence rates in five Los Angeles County census tracts; California Department of Health Services, Oakland, California, 1990.

CDHS, 1992. Cancer incidence near the SSFL laboratory, 1978-1989; California Department of Health Services, Oakland California, 1992.

CDHS, 1999. Overview of California's Perchlorate Experience. http://www.dhs.cahwnet.gov/org/ps/ddwem/chemicals/perch/perchl_overview.html, last update September 23, 1999.

CH2M Hill, 1993. Records Search and Trichloroethylene Release Assessment for the Santa Susana Field Laboratory, Ventura County, California. Prepared for the National Aeronautics and Space Administration, Doc No. MGM33496.Q0, June, 1993.

Committee to Bridge the Gap, undated. List of Accidents and Incidents at SSFL. Unpublished document, Committee to Bridge the Gap, Los Angeles, CA.

Dempsey, G., 1997. Unpublished memorandum on Area IV Radiological Characterization Survey, from G. Dempsey, EPA Radiation and Indoor Environments Laboratory, Las Vegas NV to T. Kelly, EPA Region 9, San Francisco, CA, 1997.

DeRosa, C., Brown, D., Dhara, Rosaline, et al., 1997. Dioxin and Dioxin-like Compounds in Soil, Part I: ATSDR Interim Policy Guideline, Toxicol Indust Health 13(6): 759-804.

DOE, 1990. Tiger Team Report for SSFL. U.S. Department of Energy, Washington, D.C.

EG&G, 1979. Aerial Radiological Surveys of Rockwell International Facilities. Prepared for the U.S. Nuclear Regulatory Commission by the Remote Sensing Laboratory of the U.S. DOE (Contract Report EGG-1183-1751), Las Vegas, NV, October 1979.

EPA, 1998. Perchlorate Environmental Contamination: Toxicological Review and Risk Characterization Based on Emerging Information. Review Draft. U.S. Environmental Protection Agency, Office of Research and Development, Washington, DC. NCEA-1-0503.

EPA, 1999. Perchlorate. U.S. Environmental Protection Agency, Office of Ground Water and Drinking Water.

GRC, 1993. Soil Sampling, Area I/Thermal Treatment Unit. Prepared for Rockwell International Corporation, Rocketdyne Division by Groundwater Resource Consultants, Inc. (8640M-206), Tucson AZ, August 16, 1993.

GRC, 1995. Well Compendium. Prepared for Rockwell International Corporation, Rocketdyne Division by Groundwater Resource Consultants, Inc. (8640M-89C), Tucson AZ, September 20, 1995.

GRC, 1998. 1998 Off-Site Well Inventory. Prepared for Santa Susana Field Laboratory, Boeing North American, Inc., Rocketdyne Propulsion and Power by Groundwater Resource Consultants, Inc. (8640M-361) Tucson AZ, July 9, 1998.

GRC, 1999. Annual Groundwater Monitoring Report, Santa Susana Field Laboratory, 1998. Prepared by Groundwater Resource Consultants, Tucson AZ, for Boeing North American, Inc., Ventura County, CA, 5 Volumes plus Appendices, February 24, 1999.

Hart, R.S., 1962. Distribution of fission product contamination in the SRE. AEC Research and Development Report, NAA-SR-6890 (Contract AT(11-1)-GEN-8), Atomics International, Canoga Park, CA, March 1, 1962.

ICF Kaiser, 1993. Current Conditions Report and Draft RCRA Facility Investigation Workplan, incl. Appendix F, Reported Releases at Rocketdyne SSFL, 1975-1990. Santa Susana Field Laboratory, 1993.

ICF Kaiser, 1995. Former Sodium Disposal Facility Santa Susana Field Laboratory Closure Report. Document No. SSFL-95-03. October 1995.

ITC., 1999. Draft Final Interim Measures Risk Assessment, Former Sodium Disposal Facility. IT Corporation, Pasadena, CA, July 9, 1999.

Lafflam, S.R., 1989. Letter from Mr. S.R. Lafflam, Rockwell International to Mr. D. Dickerson, California Department of Health Services, Toxic Substance Control Division, RE: Solid Waste Management Unit (SWMU) Submittal for Rockwell International Corporation, Rocketdyne Division, Santa Susana Field Laboratory, including Information Regarding Potential Releases from Solid Waste Management Units, Rockwell International, Canoga Park, CA, September 14, 1989.

McLaren/Hart, 1993. Multi-Media Sampling Report for the Brandeis-Bardin Institute and the Santa Monica Mountains Conservancy. Prepared by McLaren/Hart Environmental Engineering Corp., Irvine, CA, 6 Vols., March 10, 1993.

PEC, 1999. Windrose Data from the SSFL Meteorological Station, Precise Environmental Consultants, 1960 to present, Received November, 1999.

McLaren/Hart, 1995. Additional Soil and Water Sampling at the Brandeis-Bardin Institute and the Santa Monica Mountains Conservancy. Prepared by McLaren/Hart Environmental Engineering Corp., Irvine, CA, 6 Vols., January 1995.

Melvold, R.W., 1992. Unpublished letter from R.W. Melvold, Manager Air Quality Programs, Rocketdyne Division to Ventura County Air Pollution Control District, Subject: AB2588 ATIR, Revision B for SSFL Areas I, II, and III. Rockwell International, Rocketdyne Division, Canoga Park CA, October 13, 1992.

Morgenstern, H., et.al., 1997. Epidemiologic Study to Determine Possible Adverse Effects to Rocketdyne/Atomics International Workers from Exposure to Ionizing Radiation. Final Report to the Public Health Institute, Berkeley, CA (Subcontract No. 324A-8701-S0163), June 1997.

Morgenstern, H., et.al., 1999. Epidemiologic Study to Determine Possible Adverse Effects to Rocketdyne/Atomics International Workers from Exposure to Selected Chemicals. Addendum Report to the Public Health Institute, Berkeley, CA (Subcontract No. 324A-8701-S0163), January 1999.

Nasseri, K., 1999. Personal communication between K. Nasseri, Research Epidemiologist, Tri-Counties Regional Cancer Registry and Youn Shim, Epidemiologist ATSDR/DHS, October 22, 1999.

Oldenkamp, R.D. and Mills, J.C., 1991. Nuclear Operations at Rockwell's Santa Susana Field Laboratory- A Factual Perspective. Rockwell International Document N001ER000017, Rev. C, Canoga Park, CA, September 1991.

Ogden Inc., 1998a. Bell Canyon Area Soil Sampling Report, Ventura County, California. Ogden Environmental and Energy Services Co., Inc. San Diego, CA, October 1998.

Ogden Inc., 1998b. SSFL RCRA Facility Investigation Background Data in the Standardized Risk Assessment Methodology, Ogden Environmental and Energy Services Co., Inc. San Diego, CA, 1998.

Ogden, Inc., 1999. Unpublished Rocketdyne Santa Susana Field Laboratory Solid Waste Management Unit Map and Analytical Data. Ogden Environmental and Energy Services Co., Inc. San Diego, CA, September 1999; data to be published in November, 1999.

Robinson, K.S. (Editor), 1998. Rocketdyne Propulsion and Power DOE Operations Annual Site Environmental Report, 1997. Prepared by Rocketdyne Propulsion and Power, Boeing Inc. for U.S. DOE, Oakland Operations Office, Oakland CA, November 23, 1998.

Rocketdyne, various dates. Unpublished. Monthly Chemical Disposal Activity Reports, 1958 to 1960, Rocketdyne Inter-office Letters, Santa Susana, CA.

Rocketdyne Division, 1996. Area IV Radiological Characterization Survey, Final Report. Rockwell International, Rocketdyne Division, A4CM-ZR-0011, Five volumes, Canoga Park, CA.

Rocketdyne, 1999a. Personnel Communication with Michael Sullivan, Rocketdyne, re: Surface Drainage at the SSFL, October, 1999.

Rocketdyne, 1999b. Overview of Rocket Engine Testing and Rocket Engine Fuels and Oxidizers Used at the SSFL. Various dates (1955 to present). Received November, 1999.

Rockwell International, 1982. Letter (Ref. # 82RC03913) from J.A. Bowman, Mgr. Facilities Engineering to Mr. Richard Carlson, Ventura County Air Pollution Control District including detailed emission calculations. Rocketdyne Division, Canoga Park, CA, April 15, 1982.

Rockwell International, 1992. Area I Thermal Treatment Facility CAD 093 365 435 Revised Closure Plan. Rockwell International, Rocketdyne Division, Ventura County, CA, January 1992.

Rutherford, P.D. (Editor), 1999. Site Environmental Report for Calender Year 1998, DOE Operations at Rocketdyne Propulsion and Power RD99-115. Final Draft, Rockwell International, Rocketdyne Division, Canoga Park CA, July 1999.

Tri-Counties Regional Cancer Registry, 1997. Unpublished letter report from the Tri-Counties Regional Cancer Registry to Director, Ventura County Public Health. 1997.

Tuttle, R.J., 1991. Tritium Production and Release to Groundwater at SSFL. Rockwell International Safety Review Report No. N001SRR140120, Rockwell International Corporation, Canoga Park, CA, December 1991.

USGS, 1952. Calabasas Quadrangle, California. United States Department of the Interior, Geological Survey 7.5 Minute Series (Topographic) Map, Denver, CO.

USGS, 1967. Calabasas Quadrangle, California. United States Department of the Interior, Geological Survey 7.5 Minute Series (Topographic) Map, Denver, CO.

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