Chemistry/Forensics

Gradient evaluated the nature and extent of PCB contamination at a former rail yard Superfund site as part of a cost allocation case. We reviewed more than 15 years of chemical data from soil, sediment, and groundwater samples and collected soil samples for advanced congener fingerprinting analysis using GC/MS-SIM to aid in determining the sources of contamination.

Gradient evaluated possible sources of residential indoor air contaminants by reviewing historical data on NAPL releases in the area and collecting NAPL samples to determine the site's current state. We reviewed groundwater data, fingerprinting analyses, and reports of petroleum odor-related complaints to assess the relationship between indoor air quality and the presence of NAPL on the water table.

Gradient provided expert testimony on the sources of chlorinated solvents in a plume of contaminated groundwater adjacent to a former industrial site. We evaluated groundwater concentrations and contaminant travel times, directed the sampling and analysis of groundwater and NAPL for benzene via specialized carbon isotope analysis, and applied chemical fingerprinting techniques to distinguish industrial and non-industrial contaminant plumes.

Gradient reviewed soil sample results to determine the origin of a waste material generated during a manufacturing process. We reviewed elemental analyses, physical characteristics such as grain size, as well as Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Spectroscopy (EDS) analyses to identify the chemical or physical signatures that differentiated the waste material from other samples.