GEOPHYSICAL CHARACTERIZATION OF A FORMER REFINERY SITE, KALAMAZOO, MI

Geophysical methods are being used to characterize a former refinery site impacted with petroleum products in Kalamazoo County, Michigan. Electromagnetic Induction (EM), magnetic methods, electrical resistivity and ground penetrating radar (GPR) methods have been used.

The EM survey was done using the Geonics EM31 system. The results show areas of high conductivity (characteristic of high clay content, biodegrading hydrocarbons), There are areas of high negative signal response, which are probably areas of buried metal infrastructures. The magnetic survey like Electromagnetic induction also covered the whole study area. The maps made from this survey pinpoint areas of both buried and exposed iron or steel objects. A dipole-dipole resistivity survey covered line 720E,extending in a north-south direction for about 732ft.This survey helps to delineate zones of contamination by mapping areas of low resistivity response. The GPR survey was done on a selected area (portions of blocks 12 and 13), this area was chosen because of its low conductivity values and accessibility. The radar profiles obtained show the presence of a number of reflectors. However the reflectors are discontinuous and dipping, thus making velocity analysis with WARR difficult. The profiles also show significant signal attenuation, which is probably due to high clay content or other conductive material. The anomalies obtained from the surveys are being confirmed by manual augering. A total of six boreholes have been made and three of the six boreholes gave hydrocarbon-impacted sediments. Further work is still in progress to confirm other anomalies.