Probabilities and Possibilities in the Phase One
Environmental Site Assessment
A probable event is an event that is likely to happen or likely to have happened.
is a scale of certainty: How probable is it that an undeveloped piece
of land will be contaminated with petroleum products? Quite improbable.
possible event is an event that has or had the ability to happen. Is it
possible for the soil in the above site to be contaminated with
petroleum hydrocarbons? Of course it is. Spill a tank of gasoline on
the open land and it will readily soak in.
Probability is a scale. Possibility is yes or no. How possible is it for a cat to fly a plane?
While it is possible for a piece of land to be contaminated, the questions remains as to how probable it is.
In Phase I environmental site assessments we deal with probabilities.
We research records and inspect the site to arrive at an estimation of
the probability for environmental infliction to have happened.
we judge the probability to be beyond a certain feeling of comfort, we
move into Phase II, sampling of the soil and/or groundwater, to better
ascertain that probability.
there are no absolutes, and because economics never justify sampling
every inch of surface or depth, a degree of probability will always
remain and enter our conclusions.