|
|
DNAPLs
A type of contaminant that is especially troublesome is the group of chemicals known as dense non-aqueous phase liquids, or DNAPLs. These include chemicals used in dry cleaning, wood preservation, asphalt operations, machining, and in the production and repair of automobiles, aviation equipment, munitions, and electrical equipment. They can also be generated and released in accidents, e.g., the Hagersville, Ontario "tire fire." These substances are heavier than water and they sink quickly into the ground. This makes spills of DNAPLs more difficult to handle than spills of petroleum products. As with petroleum products, the problems are caused by groundwater dissolving some of the compounds in these volatile substances. These compounds can then move with the groundwater flow. Except in large cities, drinking water is rarely tested for these contaminants.
|