Ecological & Human Health Risk Assessment

Former Battles Gas Plant, Santa Maria, California

Former Battles Gas Plant, Santa Maria, California
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Project Name: Former Battles Gas Plant, Santa Maria, California
Services: Ecological and Human Health Risk Assessment
Client: Chevron Environmental Management Company

Historical use of the site as a gas plant impacted shallow soil with petroleum hydrocarbons, metals, and PCBs. Padre performed soil and soil gas assessment activities to characterize the nature and extent of contamination at the site. As part of this assessment an extensive soil assessment program was completed, which included the advancement of 169 drill holes and the chemical analyses of 746 soil samples.

The assessment data was used in the preparation of a Human Health Risk Assessment (HHRA) for recreational use of hardscape, indoor and outdoor commercial employees, and intrusive workers. Three scenarios were evaluated in the HHRA: (1) baseline (current) conditions; (2) following targeted remediation of soil up to 5 feet bgs; and (3) following subsequent grading of the Site with certified-clean material. Regardless of scenario, cancer risks and noncancer hazards for recreational use are well below the low end of the USEPA risk management range (one in one million; USEPA 1990) and the USEPA and Cal/EPA threshold level of 1.0, respectively. The HHRA has been approved by the Office of Environmental Health Hazard Assessment.