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Fact Sheets and Maps

Fact Sheets

The following links provide answers to frequently asked questions and important information regarding tritium and groundwater.

Off-Site Tritium Maps

The eight maps linked below outline where tritium has been detected in the groundwater both on and off Exelon property. The U.S. EPA standard for safe drinking water is 20,000 picocuries of tritium per liter of water. The areas marked with a red line on the aerial photos outline the area where groundwater measurements are above the EPA standard. There are no drinking water wells in these areas. Water drawn from outside the red areas poses no health or safety threat.

  • This aerial photo from January 2006 shows where most of the tritium in the groundwater was located.
  • This aerial map updated in March 2007 shows the change in shape of the main plume between January 2006 and January 2007.
  • This updated aerial map was created based on sampling from October 2007. The map illustrates the success of Exelon's remediation program. All offsite test wells show the tritium in the groundwater to be below the Federal drinking water standard (20,000 pCi/l).
  • This updated aerial map was created based on sampling from June 2008. The map illustrates the success of Exelon's remediation program. All offsite test wells show the tritium in the groundwater to be below 7,000 pCi/l).
  • This updated aerial map was created based on sampling from September 2008. The map illustrates the continued success of Exelon's remediation program and the reduction in the size of the plumes.
  • This updated aerial map was created based on sampling from September 2008 and March 2009.
  • This updated aerial map was created based on sampling from December 2009 and January 2010.
  • This aerial photo shows the tritium in the groundwater at vacuum breaker 4, located east of Comet Drive. The tritium is located in a small area of the Will County Forest Preserve. This area is remote from drinking wells and does not pose any health or safety threat to the public. The tritium concentration present does not threaten plants or animals.
  • This aerial photo shows the tritium in the groundwater at vacuum breakers 6 & 7. These small areas are on company property east of Essex Road and are near an area that borders the Will County Forest Preserve. These areas are remote from drinking wells and pose no health or safety threat.

Blowdown Line Map

Here is an aerial photo of the Braidwood area with markings indicating the “blowdown line” that carried the tritium prior to Nov. 23, 2005. The “VB” labels along the line indicate locations and numbers of vacuum breakers, the devices that have malfunctioned in the past causing the leaks. Since Nov. 23, the blowdown line has carried only lake water, which is pumped in and out of the lake to keep it fresh. The outflow from the lake is through this blowdown line.

Area Sampling Map

This map show sample results for both private drinking wells and wells drilled to characterize the tritium in the groundwater.

Fact Sheets and Maps