EM31 and EM61. This
density of coverage permitted the recognition of underground utilities and
culverts which often disrupt the interpretation of studies with lower density
coverage. Note in the figure above that the water pipeline produced
an EM31 anomaly 50 feet wide, but nearby waste trenches are still identifiable.
The EM61 results provide even higher resolution and minimize the "width"
of the pipeline. Both methods were used at this site because the EM31
is capable of responding to deeper targets and "filters" out small
scattered metal. As seen above, both methods detected burial trenches.
In addition, the EM61 detected many smaller objects surrounding the major
burial zones, indicating that the trenches were emplaced in larger landfilled
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Historical aerial photographs and old records indicated the presence of buried
waste materials scattered over an area of 30 acres. In planning the excavation
of these industrial wastes, knowledge of their exact extent and distribution
was required. EM conductivity and metal detector surveys were performed
with EM31 and EM61 instruments to delineate suspected burial trenches, pits,
tanks, and scattered cylinders.
Results: Many burial features were accurately
mapped by the investigation. These trenches and pits contained large concentrations
of metal such as drums and industrial debris. Several features were found
that were not identified by early reconnaissance work.
Discussion: Excavation and removal of buried
wastes could not be planned or executed without better definition of waste
than provided by historical photographs. A high density coverage of the
site was undertaken with 10 foot line spacings and data collected at 2.5 and
1 foot intervals for