Project Overview: In response to mass toxic tort litigation, Cardno ChemRisk compiled emissions information from 1976 to 2012 and performed air dispersion modeling using the CALPUFF model for a chemical manufacturing facility along the Ohio River in northwest West Virginia.  The purpose of the air dispersion modeling was to provide input into an exposure assessment of the neighboring residents.

Our Approach: Cardno ChemRisk scientists reviewed thousands of pages of engineering and air emission documents for the facility in order to estimate historical emissions of 44 different chemicals that were known to have been released from the facility.  These emission estimates were then used as inputs into the CALPUFF air dispersion model to estimate air concentrations at 1,000 receptor locations within 20 miles of the facility.  The CALPUFF model was selected because of the potential for valley effects for the facility that was located along a flat in the midst of complex terrain. As a screening level evaluation, the estimated air concentrations were compared to U.S. EPA Risk-based Screening Levels (RSLs) for ambient air and only four chemicals were identified that had estimated air concentrations above the RSLs for any of the receptor locations. This analysis was used to focus future exposure assessment activities on only those four chemicals.

Our Value: Our experience in emission estimation from historical documentation and our air dispersion modeling expertise were key factors in the success of this project.