News Release

T – 19 – 08
Maureen F. Gorsen, Director

October 10, 2008

Contact: Jeanne Garcia
(818) 717-6573

State Announces Finding Regarding Simi Valley Property
Investigations show Centex property in Dayton Canyon is safe for use

SACRAMENTO – The California Department of Toxic Substances Control (DTSC) has issued a letter to Centex Homes stating that the results of the investigation of the Dayton Canyon property do not indicate the presence of a threat to human health or the environment. DTSC cites an environmental investigation/evaluation complemented with a human health risk assessment, as the basis for its decision.

“Our decision announced today is based on three years of environmental study,” said DTSC Project Director Norman Riley. “Despite its proximity to the Santa Susana site, we conclude that there is not a presence of a threat to human health or the environment on the Centex property,” Riley added.

The environmental investigation focused on contamination in soil and groundwater. In 2005 and 2006, DTSC oversaw the analysis of soil samples collected from creek bed sediments in the eastern portion of Dayton Canyon Creek. The initial investigation found perchlorate (a chemical used in rocket fuel) contamination in soil at several locations along the creek bed, however additional sampling showed that perchlorate contamination was no longer present.

The California Department of Public Health Radiological Health Branch oversaw surveys for the radiological characterization conducted in October 2005 and March 2007.

The primary radiological constituents of concern tested for were cesium-137, strontium90, and isotopes of plutonium, which were selected = based on their use or occurrence at Santa Susana and because of community input. The report presents the results of a radiological risk assessment that concludes that potential risks to future residents are within acceptable U.S. EPA levels.

The human health risk assessment used the data from these studies, and took into consideration the potential for soil ingestion, particulate inhalation, and absorption through the skin. The risk assessment concluded that the contamination levels found at the Centex property do not present a significant risk to human health or the environment. DTSC concludes, therefore, that the property is safe.

If previously unidentified contamination is discovered at the site, additional assessment, investigation, and/or cleanup may be required. In addition, monitoring of surface water runoff from the SSFL is currently conducted by SSFL owners and operators, and the results are reviewed by the State. The results of that monitoring have indicated no problems to date. However, if in the future the monitoring data indicate significant releases of contaminants toward the 106-acre property, DTSC and/or the Los Angeles Regional Water Quality Control Board will require appropriate corrective action.

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FOR GENERAL INQUIRIES: Contact the Department of Toxic Substances Control by phone at (800) 728-6942 or visit To report illegal handling, discharge, or disposal of hazardous waste, call the Waste Alert Hotline at (800) 698-6942.

The mission of DTSC is to protect California’s people and environment from harmful effects of toxic substances by restoring contaminated properties, enforcing hazardous waste law, reducing hazardous waste generation, and encouraging the manufacture of chemically safer products.