The Wisconsin Department of Natural Resources is cleaning up contaminated soil along the Ahnapee Trail just north and west of Kewaunee. The spill resulted from a train derailment in the 1940s and has remained a source arsenic contamination in the Kewaunee Marsh area ever since.
Here’s a flyer from WDNR explaining the problem and the cleanup process.
- spraying the excavated material with a hydroxide peroxide solution to convert the arsenite to arsenate
- Mixing in ferric sulfate to precipitate (to form an insoluble solid) ferric arsenate
- Adding limestone to neutralize the reacted material
- Finally, adding bentonite to reduce the permeability (ability to transmit water) of the treated material