I recently was asked to do some oversight of a groundwater investigation at a mining facility with a chrome six groundwater plume. This particular investigation was for delineation of the leading edge of the plume, but that is not what this post is about. While I was out there, I was talking to the project manager, and I learned quite a bit about potential sources for Chrome six. Prior to this project, I was under the impression that the main source of chrome six was from chrome plating operations, corrosion inhibiting paints, or from pH changes that pushed chrome three to chrome six. Not so, in the cases of facilities with kilns, furnaces, or other high-temperature operations.
It seems that prior to the 1980s there were some high-temperature bricks that were manufactured with chrome six nodules to increase their temperature stability. Unfortunately, like many other things, these fire bricks failed, cracked, and had to be replaced. The exhausted bricks were dumped “In the back 40” where rain and irrigation water washed through the bricks releasing the chrome six laden water into the environment.
All a very interesting, and another thing to look out for when reviewing potential sources and compounds of potential concern at historic facilities.