Environmental Base Line
Environmental Enlightenment #175
In dealing with physical matters, absolutes do not exist. One establishes value only by comparison.
A “base line” is any precisely determined line forming a side of a triangle so that when the adjacent angles are measured, the relative position of a third point (the tip of the triangle opposite the base line) is determined.
In the following diagram, lines Q-V, Q-R, and R-V are base lines.
The principle of base line is used in land surveying and in navigation to locate various positions on the surface. The concepts of the base line is: establishment of an arbitrary value from which other, relative values are determined.
Certain real estate transactions take place in properties where subsurface contamination already exists or where an operation is planned that may cause contamination. For example, an operator of refueling facility enters a lease agreement on the facility, or an industrial operation takes over a property. In such cases, it would be prudent for all sides involved to establish an environmental base line on the presence of pollutants in the soil and groundwater at the property.
At the end of the lease, or in any time in the future, repeat samples can be taken, analyzed and compared. It is important to remember that, to draw sensible conclusions, the repeat sampling should be done in the exact same locations as the base line sampling. There could be reasons for future sampling in other locations and analytical tests for other chemicals, as in the case where different operations enter the property, but such sampling does not belong in the context of base line sampling.