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The blog Commonground addressed a question regarding sampling at a leaking petroleum underground storage tank site.

A January 9th post asked the following question:

Groundwater sample taken across the street from an active LUST site showed a range of petroleum chemicals, though all were at concentrations below EPA Residential RSLs. However, no soil samples were tested in the lab. Is that typical, or could there be a good reason for not testing the soil?

The reference to “LUST” is to a leaking underground storage tank site.

A January 10th post provided the following response:

I can see not testing the soil for petroleum chemicals at a perimeter groundwater monitoring well if the soil contamination plume has already been characterized and is defined. In my experience, a soil contamination plume is much smaller than the groundwater contamination plume. If that soil contamination plume has been well characterized and spatially defined, in the absence of other factors such as adjacent LUST sites, I can see not taking additional soil samples outside of that soil contamination plume, and just continuing to define the groundwater contamination plume by just placing the monitoring wells without doing soil sampling.