Description
The key was to demonstrate
the plume had more than one major source. The
complexity of the site and wealth of data required sophisticated techniques
for correct analysis. |
This site lies upgradient of a large, extensive plume
of PCE, TCE, DCE, and other dissolved chlorinated solvents.
Downgradient lies a heavily industrialized, yet suburban, area of Silicon
Valley occupied by dozens of solvent-using industries.
As part of an investigative team led by Risk-Based
Decisions (Sacramento, CA), our role included performing geostatistical
evaluations of data throughout this region; recommending locations for
sampling soil gas, soils, and groundwater; developing a three-dimensional
model of the subsurface geology, hydrogeology, and contaminant plumes; and
presenting the investigation results to the Regional Water Quality Control
Board.
Techniques used included statistical analyses of
correlations among chemical parameters ("cluster analysis"),
creating interactive three-dimensional visualizations, and
three-dimensional kriging of the complex geological structures. That process involved obtaining almost 90,000 cone penetrometer
test (CPT) readings in over 500 locations and correlating them
statistically to obtain the most precise and detailed representation of
geological structures created within this area.
Quantitative Decisions
Merion, Pennsylvania
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