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Residual Thorium Issues
As Mayor of West Chicago, I am gratified to report that any lingering questions related to the residual thorium issues raised at some homes within our community should be satisfied this year. I established a joint team with the EPA, the State of Illinois and Tronox, to encourage and track responses to our concerns. That team has remained committed to the goal of ensuring that those 32 properties initially cleaned up in the 1980s when standards were less strict, be re-tested to meet new Agency guidelines. This is being accomplished by a procedure developed by the EPA.

Since late in 2007 and 2008, 23 of the 32 properties have been tested through surface gamma scans, downhole gamma logging and soil sampling. The EPA has recently obtained access to four of the remaining nine identified properties, and testing at those properties will take place this spring. Efforts to obtain access to the last five properties continue. I have offered the City’s assistance to the EPA with those efforts. Additionally, files from both the original clean-ups in the 1980s and the 1990s/2000 were reviewed to confirm that the correct areas were targeted for this additional testing.

The EPA has completed a thorough evaluation of each of the 23 properties tested so far to address the serious concerns I have raised on behalf of our community. To date, they have done more than 1,100 boreholes, and found only 11 with any elevated reading at all. While those readings may be due to residual thorium, they may also be due to substances like fertilizers, bricks or other common materials. Those 11 boreholes were located on 8 properties, two of which are owned by Tronox and which were unoccupied houses. The EPA collected at least one soil sample from each borehole with an elevated reading and found only 5 (less than one-half percent) that had a reading above 7.2 pCi/g, which is the current clean-up standard. Those five readings were located on four properties, again two of which are owned by Tronox.

It is important to note that every elevated reading, whether from a surface scan, or downhole logging, does not mean that thorium above the clean-up standard is present. Based on the work done by EPA to date, it is clear that very little residual thorium in excess of the clean-up standard is present on the tested properties, and then only on a very few properties.

The EPA will continue its testing program until all of the questioned properties are evaluated. For those few isolated spots found to have residual thorium, the EPA will provide that information to Tronox, who has already agreed to address the findings.

I am committed to pressing the EPA and Tronox to continue to understand the City’s concerns and address them quickly, so that our community can be assured that the residual thorium question is finally behind us.


Michael B. Kwasman, Mayor