Dense Nonaqueous Phase Liquids (DNAPLs)

For more information on the DNAPL Website, please contact:

Linda Fiedler
Technology Assessment Branch
(703) 603-7194
fiedler.linda@epa.gov

Overview Policy and Guidance Chemistry and Behavior Environmental Occurrence Ethers (for future development) Halogenated alkanes (for future development) Halogenated alkenes Halogenated monaromatics (for future development) Polychlorinated biphenyls (PCBs) (for future development) Multi-Component Waste (creosotes, coal tars, heavy oils) Coal Tars Creosotes Heavy Oils Other (aniline, benzyl chloride, etc.) (for future development) Toxicology Detection and Site Characterization Treatment Technologies Conferences and Seminars Additional Resources [View Complete DNAPLs Site Map]

Environmental Occurrence

Multi-Component Waste

Coal Tars

Coal tar is a “complex oily liquid mixture” produced as a byproduct of the manufacture of coke or gas made from coal (NYS DEC, Mahler 2005, U.S. EPA 2004). Coal tar varies in consistency depending on the process by which it is made. Gas coal tar’s consistency is that of vegetable oil, which is more likely to percolate through soil and into the ground water than coal carbonized tar, which is thicker and far less likely to penetrate low-permeable layers (NYS DEC).

From 1816 to 1947, more than 11 billion gallons of coal tar were generated at manufactured gas plants in the United States (Lee et al. 1992). EPA estimates that at one time, 36,000 to 55,000 manufactured gas plant sites operated in the United States. Of these sites, about 88% are contaminated (U.S. EPA 2004). When the manufactured gas industry was thriving, waste coal tar was often buried on site, dumped into pits, or used as fill to level the land in the gas yards.

For Further Information

Cleaning Up the Nation’s Waste Sites: Markets and Technology Trends, Chapter 10
Office of Solid Waste and Emergency Response
U.S. Environmental Protection Agency (U.S. EPA), EPA 542-R-04-015, 9 pp, 2004.

This EPA market study examines the occurrence of hazardous waste problems and costs to clean them up. Chapter 10 evaluates manufactured gas plants.

Equilibrium partitioning of polycyclic aromatic hydrocarbons form coal tar into water
Lee LS, P. Suresh, C. Rao, et al.
Environ Sci Technol 26:2110-2115, 1992
(Abstract)

Parking Lot Sealcoat: An Unrecognized Source of Urban Polycyclic Aromatic Hydrocarbons
Mahler, Barbara J., Peter C. Van Metre, Thomas J. Bashara, Jennifer T. Wilson, and David A. Johns.
Environmental Science & Technology. Vol. 39, No. 15, pp 5560-5566, 2005.
(Abstract)

Contamination at MGP Sites
New York State, Department of Environmental Conservation (NYS DEC)

This website discusses manufactured gas plant operations, identifies such sites in New York, and provides information on the types of cleanup conducted on them.

Toxicological Profile for Wood Creosote, Coal Tar Creosote, Coal Tar, Coal Tar Pitch, and Coal Tar Pitch Volatiles
Agency for Toxic Substances and Disease Registry (ATSDR)
U.S. Department Of Health And Human Services, 2002, 394 pp

This profile covers coal tar creosote human health effects, chemical and physical properties, manufacturing volume data, potential for human exposure (environmental fate and transport), and analytical methods.

Other DNAPLs Environmental Occurrence Topics:

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Last updated on Thursday, July 24, 2008