“Background” means the concentration of a substance present in the environment that would exist at a location in the absence of a discharge, including substances that are ubiquitous and consistently present at or in the vicinity of the site such as:

1. (a) Coal or wood ash associated with fill material;
2. (b) Petroleum residues that are incidental to the normal operation of motor vehicles;
3. (c) Asphalt pavement and petroleum compounds contained in associated sub-base materials;
4. (d) Fertilizers in soil that were applied in a manner consistent with their labeling; and
5. (e) Pesticides in soil that were applied in a manner consistent with their labeling.

Source. (See Revision Note at chapter heading for Env-Or 600) #8812, eff 2-1-07; ss by #10831, eff 6-1-15; ss by #14159, eff 12-25-24