hazardous ranking system (HRS)
The principle screening tool used by the EPA to evaluate risks to public
health and the environment associated with abandoned or uncontrolled hazardous
waste sites. The HRS calculates a score based on the potential of hazardous
substances spreading from the site through the air, surface water, or groundwater,
and on other factors such as density and proximity of human population. This
score is the primary factor in deciding if the site should be on the National
Priorities List (NPL) and, if so, what ranking it should have compared to other
sites on the list.