Pipe failure releases 135kg of hexavalent chromium into Lake Michigan tributary
A plant owned by US Steel in Indiana released around 135kg of carcinogenic hexavalent chromium (Cr(VI)) into the Burns Waterway – a Lake Michigan tributary – over a two-day period from 11 April. The release is many hundreds of times above the daily maximum limit of 4.5kg set by state law.
The leak was caused by a failed expansion joint in a rinse water pipe. The incident closed the facility for almost a week and shut down local beaches, according to the US Environmental Protection Agency (EPA).
US Steel immediately obtained emergency permission to use a chemical agent to reduce the hexavalent chromium to less-toxic chromium-III. Hexavalent chromium levels in the water had dropped significantly within 24 hours, the EPA says. No hexavalent chromium was subsequently detected above the state permit levels, the EPA says.
US Steel has agreed to a long term monitoring plan whereby it will sample hexavalent chromium levels at the drinking water supply intake on a weekly basis until late May, overseen by the EPA and the National Park Service. The company will also sample water at Lake Michigan beaches on a weekly basis throughout the summer beach season.