Information About Soil Removed From Former Mill Site For Willits Bypass Project

Every major project Caltrans develops follows a rigorous process of environmental consideration and review that directly shapes every aspect of a project, and that process continues through construction.

Caltrans and its contractors have ensured that soil removed from a former lumber mill, currently owned by Mendocino Forest Products, is free from contamination that would make it unsuitable for fill at the Willits Bypass Project.  During an environmental assessment conducted in 2008, PCP and other chlorinated phenols associated with potential use of wood treatment chemicals were not detected. Limited detections of dioxins were identified in soil but in relatively low concentrations compared to applicable regulatory screening criteria.  Caltrans is not aware of any activities which have occurred on the site since 2008 which would have changed the conclusions of the environmental assessment.

Additional soil testing was performed in March of 2013.  The soil was tested for compaction properties and for basic contaminants. One test sample tested high in chromium, and soil was not removed near that location.  Some samples tested positive for diesel fuel, but in such a low concentration that it did not rule out its use.

More details:

AMEC Geomatrix prepared Phase I and Phase II Environmental Site Assessments (ESAs) of the former mill facility in 2008. The results of the Phase I ESA indicated that the mill had been operating as early as 1961, it was permanently closed in 2005, and that potential contaminants included petroleum hydrocarbons, pentachlorophenol (PCP) and dioxins associated with wood with wood treatment chemicals, and polychlorinated biphenyl (PCB)-containing oil released to soil from an electrical transformer.

Soil and groundwater samples were collected by AMEC Geomatrix and analyzed for petroleum hydrocarbons, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), chlorinated phenols, dioxins and furans, and heavy metals.  Limited detections of diesel and motor oil, PAHs related to petroleum constituents, and dioxins were identified in soil at relatively low concentrations compared to applicable regulatory screening criteria.  PCP and other chlorinated phenols associated with potential use of wood treatment chemicals were not detected in each soil sample analyzed.  AMEC Geomatrix concluded that no further investigation was necessary.