Leak at Illinois carbon capture facility could impact drinking water

There are new concerns that Archer Daniel Midland Co.’s (ADM) carbon injection site in Decatur, IL, could be leaking highly corrosive liquid carbon into the local drinking water supply. 

The company, which reported two leaks earlier this year, recently reported to federal regulators that it found 24 wells, drilled for various purposes over the years, located at the site of one of the leaks, increasing the risk of the carbon dioxide migrating towards drinking water. 

ADM estimates that in the first leak, 4,000 metric tons of liquid carbon dioxide escaped above the layer of shale rock that is supposed to contain stored CO2 from the site. There are two additional layers of shale that separate the leaked carbon dioxide from the Mahomet aquifer, which provides drinking water to nearly one million people in central Illinois. The wells are located in one of those layers of shale. 

ADM maintains that their modeling shows that the leaked liquid will remain well below drinking water sources, and an EPA spokesperson says there is no immediate threat to drinking water. But some experts worry that having so many wells nearby makes it much more difficult to accurately predict where the fluid will migrate, and that it is unlikely ADM could have produced an adequately sophisticated model so quickly. 

The Mahomet Aquifer is a sole-source aquifer, meaning any contamination could be devastating for those who rely on it. A new state law passed in July to regulate carbon capture in the state did not provide any protection for the aquifer. ADM’s Decatur site hosts two of just four fully operational carbon sequestration wells in the country. If the facility is unable to safely store carbon dioxide, it raises questions about whether carbon sequestration can be done safely at all.