GEOPHYSICAL ASSESSMENT OF AN ACTIVE NORTHERN ILLINOIS LANDFILL

The 800 Area landfill at Argonne National Laboratory operated from 1966 until September 1992. It primarily received solid non-radioactive waste as well as liquid hazardous wastes. The landfill is underlain by approximately 45 m of silty clay till, overlying Silurian dolomite bedrock. Well bores completed on the landfill encountered refuse to depths of 15 m. Targets of geophysical surveys performed at the site include leachate mounding, leakage of leachate below the landfill, and mapping of discrete disposal areas (e.g. an "asbestos disposal area" in the northeast portion of the landfill). Dipole-dipole resistivity lines, collected in 1990 while the landfill was still in operation, reveal electrical properties of landfilled materials and possible leachate accumulations within the refuse. Preliminary results suggest dipole-dipole resistivity surveys will not be able to accurately determine electrical properties deep enough to assess leakage below the landfill. Such surveys, however, identified a layered structure possibly from buried refuse “lifts.” The surveys also show striking resistivity heterogeneity within each layer, and possible areas of leachate accumulation. Results are consistent with EM and magnetic surveys conducted over the landfill and wells drilled both pre- and post-closure.