There is new concern in Le Mars, Iowa, about possible groundwater contamination from an old coal gas plant. The Environmental Protection Agency oversaw a cleanup there in 2004. There are 12 monitoring wells that regularly provide samples of the groundwater and now the EPA wants to drill three new wells into the Dakota aquifer to see if any of the contamination has spread beyond its earliest known range.
Coal gas was widely used for cooking, lighting and heating throughout the 1800s, and even into the early 20th century. Also called manufactured gas plants, the system of tanks and pipes used to make gas from coal was eventually incorporated into modern electric generation plants because the gas produced had very low sulphur making it easier on the environment when it is burned. The coal tar left over from the gasification process however has an amazing mix of polycyclic aromatic hydrocarbons (PAH) and volatile organic compounds (VOC). There are also cyanide salts left over in the iron oxide waste created from purifying the gas.
The makers of coal gas often sold the tar or simply buried it in pits. The cyanide-laced iron oxide was typically buried or dumped.