Description
A suburban site like this is
in the public eye. All actions are closely scrutinized. Field
screening data can be very useful, provided they can be correlated with
higher-quality data. Inverse linear regression is a correlation
technique. The
three-dimensional analysis was essential, because the highest concentrations
typically were deep. |
This small (25 acre) site lies in the
heart of suburban Long Island. Large amounts of chromium and cadmium
had been identified and removed in one area, but the US EPA required a
comprehensive investigation and cleanup of the remainder of the site.
We designed an investigation that met the US EPA
requirements but cost substantially less than the plan they had
suggested. Using inverse linear regression, we were able to
exploit extensive preliminary field screening data and to avoid obtaining
large amounts of expensive analytical results (SPLP tests).
With these results we used a Geographic Information
System (GIS) to identify "hot spots" in soils and to delineate
them in three dimensions. To estimate cleanup costs, this GIS was
then able to account for practical constraints, such as computing the
volumes of overburden required to reach deep isolated hot spots. As
a result, we were able to generate cost-benefit curves showing how the net
reduction in mean concentrations varied with potential cleanup
effort. These curves demonstrated a rapid decrease in effectiveness
after cleanup proceeded beyond surgical removal of the highest
concentrations.
This work has been the basis of all subsequent
evaluation and decision-making concerning soils cleanup at the site.
Quantitative Decisions
Merion, Pennsylvania
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