Sauk Village Water Supply Contamination Issue, Cook County, Illinois

              State of Illinois
Pat Quinn, Governor
Illinois Environmental Protection Agency
John Kim, Interim Director
Illinois Environmental Protection Agency
Office of Community Relations
1021 N. Grand Avenue East
Springfield, Illinois 62702
www.epa.state.il.us
Phone: (217) 782-2829
Fax: (217) 785-7725
TDD: (217) 782-9143
March 2012
Fact Sheet # 1
Sauk Village Water Supply Contamination Issue
Cook County, Illinois
Background
In June 2009, Illinois EPA mailed public notices to all Sauk Village Water Supply users regarding vinyl chloride contamination in groundwater that is affecting the community water supply. In the water drawn from Well Number 3, the concentration of vinyl chloride in 2009 [at 3.49 micrograms per liter (ug/L)] violated the federal maximum contaminant level of 2 ug/L allowed for a public water supply. Well Number 3 was taken out of service in 2009 and has not been part of the system since then because of the vinyl chloride contamination.
Vinyl chloride is a chemical from a family of chemicals known as volatile organic compounds (VOCs) that are related to industrial and commercial cleaning solvents among other uses. These chemicals tend to vaporize readily into the air once brought to the surface – at a faucet, for example. When in ground- water, however, they are resistant to breakdown and tend to remain for many years and can move slowly with the groundwater gradient (the groundwater flow direction).
Two other Sauk Village wells provide water into the treatment system for the community water supply, and the point where the water enters the system has been monitored quarterly for the contaminant of concern – vinyl chloride – along with other contaminants that may affect public water supplies.
In 2010, Illinois EPA helped develop legislation that allows for early notification to community water supply (CWS) users about the presence of a cancer-causing VOC chemical at one-half the federal drinking water standard, known as the maximum contaminant level (MCL). The legislation compels water supplies to develop a plan that will prevent a violation of the MCL in the finished water. Additionally, the plan must demonstrate how the CWS will reduce the concentration of the VOC so that its concentration is less than what can be detected through standard methods. The Illinois EPA and the Illinois Office of the Attorney General are pursuing legal enforcement against Sauk Village to correct water quality and water quantity problems related to the community water supply.
Is the Sauk community water supply currently safe to drink? The community water supply has been meeting state and federal water quality standards since Well Number 3 was taken out of service in 2009. However, the two remaining wells are showing low levels of vinyl chloride, and are being routinely monitored for water quality. If the concentration of vinyl chloride or any other contaminant reaches one-half the MCL, Illinois law requires that the water supply operator notify all supply users. Illinois EPA routinely reviews all the laboratory results of the water supply, and will make sure notice occurs. Can the vinyl chloride be removed from the well water? Yes. There are various forms of treatment to remove the contamination after the well water is drawn at the well, before it goes into the system that delivers water to the users.