Braun Intertec was engaged by Coastal Plating, Inc. to address a release of hexavalent chromium into soil and groundwater at their Carson, California metal finishing facility. The contamination originated from a breach in the secondary containment of the anodizing line. Our team managed all aspects of the investigation, full-scale remediation design, and implementation, including regulatory coordination and permitting. The project was conducted under the oversight of the Los Angeles Regional Water Quality Control Board. We also facilitated cost recovery through insurance claims.

Our team performed multiple phases of investigation to delineate the vertical and horizontal extent of contamination, which reached depths of up to 50 feet below ground surface (bgs), impacting both soil and groundwater. Bench-scale testing was conducted to evaluate chemical stabilization options. Calcium polysulfide (marketed as REMOTOX®) was selected for its effectiveness in reducing toxic and soluble hexavalent chromium to less toxic and insoluble trivalent chromium. Investigative results and bench-scale testing were used to design a Remedial Action Plan (RAP), which received approval from the Regional Water Quality Control Board.

A pilot injection test was conducted to refine design parameters, followed by full-scale remediation over two months in early 2025. Using direct-push injection methods, approximately 474,000 gallons of REMOTOX® solution was injected beneath and surrounding the anodizing line. Preliminary results showed a reduction of hexavalent chromium concentrations in soil by 83% to 89% on average within just 30 days of treatment. 

Our team continues to perform quarterly groundwater monitoring to evaluate the long-term effectiveness of the remediation. Groundwater containment pumping with recirculation and reinjection will also be implemented to control plume migration.

We have also provided environmental investigation services at other facilities for this client in California, including assessment of PFAS impacts related to historic mist suppressant use in chromic acid baths.