Crestwood Public Drinking Water Supply Contamination

Crestwood Groundwater

Update #1
June 2009

Village of Crestwood, Cook County

Map of private well sampling locations
Private Well Sampling Locations
Aerial photo of June 2009 environmental investigation area
June 2009 environmental investigation area

Current Activities

Illinois EPA investigations continue concerning the illegal use of the tainted Crestwood Public Water Supply (PWS) well and the origins of the volatile organic compounds (VOCs) found in the PWS well which we are currently attributing to drycleaner solvent breakdown products.

  • Crestwood’s well was sealed in March 2009 and an Illinois EPA records analysis has confirmed that only Lake Michigan water has been used by the Crestwood PWS since November 2007. In April 2009, chemical analysis of water samples from the Crestwood PWS distribution system did not detect contamination by vinyl chloride and other VOCs. These data provide independent verification that residual well water from the well’s last documented use in November of 2007 does not remain in the PWS storage tank system.

  • In early May 2009, our field staff collected samples from three private wells 2000-3000 feet south, southwest, and west of the suspected source area. These samples were collected between the known contamination -- at the suspected source site and the former Crestwood PWS well -- and the rest of the Village. These samples have all been analyzed resulting in no detections of VOCs. However, since our information indicates that groundwater flows northeasterly in this area, discharging to the Calumet-Sag Channel, we believe that these wells are not in the path of contaminated groundwater from the suspected source. During this preliminary investigation, no wells could be found in the path of groundwater flow from the known area of contamination.

  • Once property access for sampling can be obtained and drilling equipment, personnel and laboratory schedules can be coordinated, further field work by the Illinois EPA will begin in early June to find the extent of the drycleaner release contamination. Soil and groundwater investigations to determine the extent of contamination typically begin at the suspected source and “step out” from there, as contamination is traced through the environment.

    During the June field work, investigations will focus on the Playfield Plaza shopping center property and east and south to the former Crestwood PWS well. In addition to these activities, we will try to verify groundwater flow direction within the immediate area. Knowing the precise flow direction should help answer questions about whether the drycleaner site at the shopping center was responsible for the Crestwood PWS well contamination and whether private wells in the immediate area could be threatened. No private well sampling will be performed as part of this phase of the investigation.

Meanwhile, Governor Pat Quinn, the Illinois EPA, the Attorney General’s Office and the Illinois General Assembly worked together to craft legislation in an effort to prevent this situation from occurring elsewhere in Illinois.

  • House Bill (HB) 4021, passed by both legislative chambers, adds specific noticing requirements to existing Right-to-Know provisions in Illinois law and makes it a felony to knowingly make false statements to the Illinois EPA or its representative concerning compliance with Illinois’ Environmental Protection Act or any federal law or regulation administered by the Agency. The bill requires notice whenever the public is at risk due to a contaminant release that could cause a vapor intrusion problem (vapor from contaminants in soil or groundwater migrating into buildings). Notice is also required: if the Illinois EPA determines that groundwater contamination poses a threat to the public from contaminated public drinking water supplies; if the Agency refers a water supply system-related matter to the Illinois Attorney General’s Office for enforcement action, or; if the Agency issues a seal order for such a system. The bill also requires owners or operators of these systems to maintain records required to document the operation of the system for at least 10 years, including billing records and documents related to the purchase of water from other public water supplies. (For more information, go to the Illinois General Assembly’s legislation web page at and click on House Bill 4021.)

Frequently Asked Questions

Illinois EPA’s Fact Sheet of May 8, 2009 talks about Crestwood residents drinking contaminated water from the PWS, but we also bathed and showered in it, and cooked with it for the 10 years during which the Illinois EPA believes it may have been contaminated with vinyl chloride. What additional exposure did we get by breathing the vapors?

Although we have limited data to calculate the exposure residents may have experienced via any pathway (breathing, drinking or skin exposures), the exposure calculation, prepared by the Illinois EPA in consultation with the Illinois Department of Public Health (IDPH), used an exposure scenario built on assumptions chosen to err on the side of the highest reasonable exposure a resident may have experienced. We consider these assumptions to be “conservative,” or very protective of the exposed population: we calculated a 70-year exposure while drinking the water at the highest known concentration of vinyl chloride found in the well water just before it was taken out of service in November of 2007. We also used the highest percentage of well water, 20 percent, found to have been blended with the Lake Michigan water supply when calculating the exposure risk. We purposely chose these conservative assumptions so as not to underestimate the actual exposures residents may have experienced. Illinois EPA believes that the exposure scenario is so conservative that it actually overstates the risk from drinking the water for several reasons, including:

  1. No vinyl chloride was found in the well water samples collected in 1985 and 1986. We also have a report of two Crestwood PWS well sample results from early 1998 that tell us there was no vinyl chloride detected in the well at that time either, indicating that the actual exposure to low concentrations of vinyl chloride in the well water blended with Lake Michigan water began sometime during the ten years between early 1998 and ending in late 2007, rather than the exposure we calculated occurring over a 70-year lifetime;
  2. Vinyl chloride is most often found in the environment as a breakdown product of the drycleaner solvent, perchloroethylene. Vinyl chloride typically appears gradually over time as bacterial action in the groundwater degrades the solvent. The drycleaner solvent and breakdown products are more dense than water so they typically sink in groundwater; usually the deeper in the groundwater, the less oxygen is available to support the bacteria which degrade the chemicals to vinyl chloride. Using the highest vinyl chloride concentration, found just before the well was taken out of service, overestimates the concentration we expect would have existed over the potential 10-year exposure period;
  3. Vinyl chloride is a gas. As the well water was pumped and mixed with the Lake Michigan water in two, one million gallon PWS tanks located along the Calumet-Sag Channel, we would expect some of this gaseous chemical to evaporate out of the water and dissipate into the outdoor air. However, we did not account for this evaporation by subtracting it from our calculations of vinyl chloride in the distributed PWS water.

Exposure to vinyl chloride was used to calculate risk because it was the only chemical found above the drinking water standards, and drinking the water is the most important pathway for vinyl chloride to pose risks to exposed residents. Exposure via the skin while showering or bathing would be insignificant since the gas, vinyl chloride, would evaporate very quickly from hot water. Because this risk calculation overestimates the actual risk from the vinyl chloride exposure, any additional risk from the inhalation of very small amounts of vinyl chloride during cooking or showering between 1998 and 2007 should already be accounted for in the conservatively calculated risk estimate. This theoretical risk due to vinyl chloride exposure is a potential for 2 to 4 additional cancers to occur in a population of 100,000 over a 70 year period. Even if inhalation risks were not accounted for in the risk estimate, we could use another conservative assumption – assuming the exposure to vinyl chloride from inhaling vapors that passed into indoor air equaled the exposure from drinking the water -- that would double the potential vinyl chloride exposure. This would result in a maximal lifetime cancer risk due to vinyl chloride exposure of between 4 and 8 in 100,000. To put this risk in perspective, the lifetime cancer risk in the U.S. is approximately 1 for every 3 people.

We also drank, bathed and showered in the blended well water/Lake Michigan water and cooked with it for the 10+ years before the appearance of the vinyl chloride, during which time the water was contaminated with other drycleaner solvent breakdown products. What risk does exposure to these solvents from 1985-2007 add to the vinyl chloride exposure risk?

Again, Illinois EPA has limited data available to us to answer this question. The data set we have is limited to a handful of samples collected and analyzed in 1985-86, 1998 and 2007. The Safe Drinking Water Act establishes Maximum Contaminant Levels (MCLs) allowable in public drinking water supplies; all of the sample data we have reflect concentrations of the various chemicals below their respective MCLs.

In 1985, 2.8 parts per billion (ppb) of 1,1–dichloroethylene (DCE) was found in the PWS well water by Illinois EPA. In 1986, Crestwood found 4 ppb of trans-1,2 DCE; the confirmation sample taken in November 1986 indicated 5 ppb of trans-1,2 DCE. These concentrations were all below the now allowable limit, or MCL, of 7 ppb for 1,1-DCE and 100 ppb for trans-1,2 DCE. (These MCLs did not exist in 1985-86 but only became effective several years later.)

Results from the early 1998 Crestwood PWS well samples taken by a consultant investigating a drycleaner solvent release nearby, found cis-1,2-DCE at 3 ppb in both samples (MCL is 70 ppb) but no vinyl chloride was reported.

Finally, the September 2007 sample collected by Crestwood found vinyl chloride at a concentration of 1.5 ppb (MCL is 2 ppb) and cis-1,2-DCE at 2.6 ppb (MCL is 70 ppb). Illinois EPA’s confirmation sample collected in October 2007 found 5.4 ppb of vinyl chloride and 1.61 ppb of cis-1,2-DCE. The well’s use was discontinued shortly thereafter, in November of 2007.

The Illinois EPA has no information that any of the drycleaner breakdown products, other than vinyl chloride, were ever in the Crestwood PWS well at concentrations greater than their respective MCL. MCLs are considered by the U.S. EPA to be the maximum level of a contaminant at which no known or anticipated adverse human health effect would occur, and which allows an adequate margin of safety. Thus we believe that, throughout this time period, the exposures to chemicals other than vinyl chloride did not add to anyone’s health risk.

What if I used this contaminated water for my garden?

Vinyl chloride is a stable and persistent chemical when it is found deep in groundwater where there is no oxygen to help bacteria break it down into harmless molecules. When vinyl chloride is exposed to sunlight, air and soil bacteria in the garden, it rapidly breaks down and is not absorbed by the plants. Rapid degradation also occurs with the other volatile organic chemicals that we suspect were present at low levels during the 20-year period. Gardeners who watered their gardens with Crestwood PWS well water from 1985 through 2007 and ate their garden produce are not at risk from the vinyl chloride and other VOCs in the Crestwood water.

I live in unincorporated Palos Heights and receive Crestwood PWS water. Are there any other areas served by the Crestwood PWS whose residents may not realize that water was being sold to their township or municipality by Crestwood?

A part of unincorporated Palos Heights is part of Crestwood’s PWS distribution system. Crestwood village officials report that the only unincorporated area receiving Crestwood PWS water is the area bounded by 127th Street on the north to 131st Street on the south (1/2 mile) and by Monitor Avenue on the east to Austin Avenue on the west (1/4 mile); a total of 93 homes in this area are reportedly served by Crestwood PWS water. If you receive Crestwood PWS water in this unincorporated area, Crestwood reports that your water bill comes directly from the Village of Crestwood.

During Illinois EPA’s investigations of the Crestwood PWS, we have reviewed Crestwood’s PWS logs, billing records and our PWS database and have confirmed that Crestwood water was not sold to other entities. Our inspector also cross-checked the PWS database to verify the water sources for villages bordering Crestwood, such as Tinley Park, Palos Heights and Palos Park; all of them get their water from sources other than Crestwood.

When the groundwater contamination was discovered in 1986, were any investigations performed to determine where the chemicals were coming from and how far they had migrated? Does Illinois EPA have any reports or maps that show the physical extent of the groundwater contaminant plume?

No; the Illinois EPA’s Division of Public Water Supplies provided the results of our 1985 sampling to Crestwood and required the PWS to begin quarterly testing for the class of chemicals, VOCs, found in the water. Crestwood purported to use only Lake Michigan water from 1986 onward, so these well water monitoring requirements were not enforced. The Agency has no authority to require a PWS to perform environmental investigations to identify potential sources of PWS well contamination and does not have the resources to unilaterally and routinely perform such investigations ourselves.

However, in the mid-1980's, we initiated a program to assess all Illinois Community Water Supply wells with chemical contaminants detected and rank them for their potential hazard to human health. As these wells were assessed, they were referred to the U.S. EPA for further investigation. The vast majority of these early referrals for investigations by U.S. EPA’s contractors resulted in decisions that no further action would be taken to determine the origins of contamination when a PWS was switching from a groundwater source to a surface water source. This information is documented in the Illinois Groundwater Protection Program Biennial Reports (1990-1994). Since Crestwood had indicated their source water was a surface water source, Lake Michigan, and the previously referred PWS wells whose supplies had switched from groundwater to surface water resulted in No Further Action determinations, the Illinois EPA did not rank the Crestwood well and refer it to U.S. EPA.

During the 1990s, two different environmental consultants provided some minimal data (Phase I and Phase II environmental assessments) to Illinois EPA’s voluntary site cleanup program concerning drycleaner solvent contamination at a nearby shopping center but no further investigation reports were provided to document the extent of soil and groundwater contamination. Phase I and Phase II environmental assessments are often performed in preparation to sell commercial properties and rely largely on existing data, collected from various environmental databases and file searches, with very minimal original sampling performed. They are not the in-depth environmental investigations that generate thorough site data and comprehensively document the nature and extent of contamination, including the creation of groundwater contaminant plume maps.

The current property owner is cooperating fully with the Illinois EPA’s current environmental investigation. The Illinois EPA will continue its investigation into the origins of the Crestwood PWS well contamination, as discussed at the beginning of this Update. As results of the investigation become available, the Illinois EPA will post them on our web site (go to the link below).

If I have any questions, where can I find more information?

Residents with questions for Illinois EPA should contact:

Mara McGinnis (phone 217-524-3288; e-mail to:
Office of Community Relations, Illinois EPA

This fact sheet update, along with the original May 8, 2009 Crestwood fact sheet, can be found at: (see Crestwood) or at the Crestwood Public Library District. Any further updates from the Illinois EPA concerning Crestwood, including the environmental investigation results, will be posted on this web page.

Residents with specific health-related questions or concerns about private wells should contact:

Tom Baughman (phone 630-293-6800; e-mail to:
Toxicology Section, IDPH West Chicago Regional Office