Weiss Associates

Key Project Elements:

  • Identification and assessment of PCBs
  • Analysis of transport of contaminants within a watershed
  • Development of a site conceptual model

Assessment of PCB-contaminated Sediment

Palo Alto, California

At a large industrial facility near San Francisco Bay, elevated polychlorinated biphenyl (PCB) concentrations were detected in surface swales and drainage channels. Weiss Associates was retained to develop a site conceptual model (SCM) for entry of PCBs into the environment and movement of PCBs through the watershed.

Weiss Associates reviewed historical documents, material safety data sheets, and analytical data to identify potential PCB sources in building materials, chemical use and storage areas and electrical equipment. We analyzed topographic maps and storm drain inspection videos to evaluate the transport of PCBs adsorbed to sediment particles via storm water flow. Based on this information, a SCM was developed to explain buildup of PCB residues on pavement and building surfaces due to chemical spills, degradation of building materials and the historical application of PCB oil for vegetation control. The SCM focuses the current investigation and removal actions to cost-effectively eliminate PCB sources and transport pathways.

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