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Figure 1. City of Delavan, Walworth County, Wisconsin

Figure 2. Wells No. 3 and No. 4, City of Delavan, Wisconsin

Figure 3. Monthly Pumping Rates of Delavan Wells No. 3 and No. 4

Figure 4. City of Delavan, Wisconsin


ATSDR:The Agency for Toxic Substance Disease Registry, a federal agency.
Cancer Risk Evaluation Guide (CREG):A concentration of a carcinogen in a media (water, soil, or air) at which excesscancer risk is not likely to exceed one case of cancer in one million persons exposed over a lifetime.
Cancer Slope Factor (CSF):The upper limit on the lifetime probability (at or less than 1 in 1,000,000) thata cancer causing chemical will cause cancer at a dose of 1.0 mg/kg/day.
Carcinogen:A substance which has been proven to cause or is suspected of causing cancer in humans or animals.
CERCLA:The Comprehensive Environmental Response, Compensation, andEnvironmental Liability Act. Also known as "Superfund", this program isadministered by the U.S. Environmental Protection Agency.
DOH:Division of Health, Wisconsin Department of Health & Social Services.
DNR:Wisconsin Department of Natural Resources
Groundwater Enforcement Standards (and Preventive Action Limit Standards):Health-based groundwater goals set by the Wisconsin DNR that whenexceeded prompt regulatory action. Established under the Wisconsin Statutefor Groundwater Quality, Chapter NR-140.
mg/kg/day:Milligrams per Kilograms per Day
mg/kg:Milligrams per Kilogram (soil concentration measurement)
National Priorities List (NPL):U.S. EPA's list of top priority hazardous waste sites that are eligible for investigation and cleanup under Superfund.
PCE:Tetrachloroethylene or Perchloroethylene.
PPB:Parts Per Billion or Micrograms per Liter (µg/L or µg/kg).
PPM:Parts Per Million or Milligrams per Liter (mg/L or mg/kg).
Remedial Investigation and Feasibility Study (RI/FS):Two parts of the Superfund process. The Remedial Investigation includes thecollection and evaluation of data to define site conditions, including the natureof hazardous substances found at a site and the extent that those hazardoussubstances were released from the site. These releases are evaluated to assessthe effect on public health and the environment. The Feasibility Study definesa range of likely alternatives for cleaning up a site.
SVOC:Semi-Volatile Organic Compounds
U.S. EPA:United States Environmental Protection Agency
µg/L:Micrograms per Liter or Parts Per Billion (water concentration measurement)
VOC:Volatile Organic Compounds

Pathways are evaluated to determine whether nearby residents have been exposed to contaminants originating from the site. A pathway is a route along which contaminants can move away from a site and enter the bodies of people living nearby. There are five elements in a completed pathway:


Pathways Evaluation
1)Contaminant Source: The place where contaminants entering theenvironment are coming from.
2)Media: a media that the contamination is found in (soil, sediment,groundwater, air, surface water, fish, and game animals).
3)Exposure Point: the location at which human contact is made with thecontamination. The Exposure Point is specific to each type of media(e.g. - groundwater, surface water, soil, etc.)
4)Exposure Route: the process by which the contaminated media getsinside of people (eating/drinking, skin/dermal contact, or inhaling).
5)Receptor Population: groups of people who are or may be exposed.

APPENDIX D: Toxicological Evaluation - Cancer Risk Estimation Methods

In estimating lifetime excess cancer risk, the following formula [4, P47] is used:

annual exposure dose (mg/kg/day) × cancer slope factor (mg/kg/day)-1 × exposure factor in years

The result of calculating a cancer risk estimate from this formula is then applied to the followingtable to quantify the risk estimate:

Quantitative Risk
Qualitative Risk Interpretation
"insignificant or no increased risk"
"no apparent increased risk"
"low increased risk"
"moderate increased risk"
"high increased risk"
"very high increased risk"


    No apparent increased risk of cancer from a 12-year exposure to the average estimatedPCE level found in Delavan Well No. 4 (page 26): Assuming that tetrachloroethylene(PCE) is a carcinogen, as previously determined by the U.S. EPA, and the cancerscreening value is used (Cancer Slope Factor [5.1E-02] is 0.69 µg/l), this 1:1,000,000risk level was exceeded by all the levels detected in Well No. 4. Assuming the combinedexposure of all three routes (dermal, ingestion, and inhalation) is three times thatexpected from drinking water alone, this combines to create a total PCE exposureequivalent to 99 µg/L, and converts to 3.0 µg/kg/day or 0.003 mg/kg/day (70 kg adultdrinking 2 liters of water per day). Excess cancer risk is estimated based on an adultbeing exposed to the cancer causing substance for a lifetime, or 70 years. Thisestimation assumes that Delavan residents were exposed to PCE for a period no longerthan 12 years. Using the U.S. EPA's former cancer slope factor it is estimated that aperson exposed to drinking water contaminated at 33 µg/l for 12 years would have "noapparent increased risk" of cancer ([0.003 x 5.1E-02 x 12/70] = [1.53E-04 x 12/70] =2.6E-05). There are no other known health effects from ingesting the highest level ofPCE detected in Delavan Well No. 4.


    No apparent increased risk of cancer from a 12-year exposure to the average estimatedTCE level found in Delavan Well No. 4 (page 27): Assuming trichloroethylene (TCE) isa carcinogen, as previously defined by the U.S. EPA, and a Cancer Slope Factor of1.1E-02, this value was exceeded by most levels detected in Well No. 4. Combinedingestion, inhalation and dermal exposures would then total an equivalent TCE exposureof 732 µg/L. This converts to 20.9 g/kg/day or 0.0209 mg/kg/day (70 kg adult drinking2 liters of water per day). Excess cancer risk is estimated based on an adult beingexposed to the cancer causing substance for a lifetime, or 70 years. This estimationassumes that Delavan residents were exposed to TCE for a period no longer than 12years. Using the slope factor it is estimated a person drinking water contaminated at 244µg/l for 12 years would have "no apparent increased risk" of cancer ([0.0209 x 1.1E-02 x12/70] = [2.3E-04 x 12/70] = 3.9E-05.

APPENDIX E: Response to Public Comments

  1. "The health assessment report is out of scope. The report covers beyond the "site" [WellNo. 4]. Other health concerns may exist due to other releases unrelated to this project,however, the purpose from my understanding of this report is to verify the healthconcerns of the Superfund Site. The geology and hydrogeology should be left to peoplein those sciences. The Superfund Site is Well No. 4, not all of the groundwater aquifersof Delavan."
      A public health assessment is the evaluation of data and information on the release ofhazardous substances into the environment in order to assess any past, current orfuture impact on public health. To fully assess the impact of hazardous substances onpeople who live near a hazardous waste site, public health assessments must evaluatea total environmental exposure to site-related substances. Therefore, public healthassessments examine potential human exposure to site-related hazardous substanceswithin a media that may have multiple sources, including possible nearby sources nottechnically defined as "Well No. 4."

      Groundwater contamination by chlorinated volatile organic compounds has beenfound at many contiguous locations in the Delavan area. This public healthassessment examines all available environmental sampling data in order to providecitizens with an accurate evaluation of the human health implications of this groundwater contamination.

      A multidisciplinary team participates in the preparation and review each public healthassessment. Each participant brings specific environmental health expertise to theteam. The following specialists were involved with the preparation and review ofthis public health assessment: epidemiologist, environmental engineer, environmentalhealth specialist, toxicologist, health educator, chemist, and hydrogeologist.

  2. "The report also seems to follow its own path and not the table of contents. Backgroundinformation should be presented in background information section and not redundantlythroughout the report. Background information should be the largest section of thereport. The type face for sections under background are not consistent. It appears thatthe sub,sub-sections Sta-Rite, Investigations and Follow-up Activities should be theirown section. The report should have a Remedial Action Section."
      Public health assessments, including the format of the report follow clear trainingand guidance criteria set forth under the "Public Health Assessment GuidanceManual"[5], and subsequent guidance documents provided to preparers by the Agencyfor Toxic Substances and Disease Registry, under the U.S. Public Health Service.
  3. If the Health Department felt that there were "data gaps," the Health Department shouldhave collected samples to fill the gaps. The Health Department came out to sampleprivate wells, why not then sample the points where the Health Department feels datawould have been so valuable.
      In preparing the public health assessment reports, the Wisconsin Department ofHealth and Family Services (DHFS) relies on environmental sampling data collectedby the U.S. Environmental Protection Agency, the Wisconsin Department of NaturalResources, and potentially responsible parties and their contractors. The publichealth assessment presents recommendations, which may include the need foradditional data that would provide a clearer picture of the extent of contaminationand potential human exposures. When additional sampling is needed to fill data gaps,DHFS will communicate the need for additional sampling efforts with one of theseagencies. However, DHFS does not typically collect environmental samples foranalysis unless there is a concern that a contaminated media may pose a health hazardto the public. In Delavan, DHFS worked closely with DNR to ensure that privatewells were sampled. Many of the private wells were tested by DNR. DHFS staffcollected a sample from a private well as requested by a citizen.
  4. The report states that five VOCs were found in Well No. 4, list them. Do not leave thereader guessing, for instance, when a reference was made to a sample where more than13 compounds were detected. If references are made to analytical data and compoundsdetected, the compounds and level of detection should be listed, as to not leave the readerguessing to the level of detection.
      Public health assessments examine the potential human health issues of contaminantsin the environment. While a myriad of hazardous substances are found in media onand around a site, only those substance which might pose a possible human healthhazard are evaluated in-depth within a public health assessment. The report mayindicate that other unspecific chemicals were present at a site (either substances thatare hazardous or those at such levels not known to pose a human health hazard), butthe report is prepared to minimize burdening readers with the details of substancesthat are clearly not a health hazard. This information is included in the report toindicate to the reader that these data are available. Interested readers can obtain moredetailed, chemical-specific information from the source document, the preparer of thereport, or the information repository on Well No. 4 at the public library in Delavan.
  5. The author says the vertical and horizontal extent of the plume has not been defined andleads the reader this think that Sta-Rite and the DNR are not addressing the problem. The vertical and horizontal extent of the plume has been defined. A clear casehydrogeologically has been made to demonstrate that Plant 1 is hydraulically isolatedfrom the influence of Well No. 4. In addition chemically, the contamination from the twoplants has its own distinct finger print. [Contamination at] Plant 2 matches with[contaminants found in] Municipal Well No. 4.
      Sta-Rite-initiated environmental investigations of contamination off the Sta-Riteproperty have primarily focused on impacts to Well No. 4. These investigations havenot proven that Well No. 4 captures all contaminated groundwater migrating awayfrom Sta-Rite Plant 2. Sampling of groundwater from monitoring wells on AnnStreet and west of Well No. 4 shows impacts from some of the same contaminantsfound in the municipal well and at the Sta-Rite property. It should be noted thatgroundwater modeling suggests these monitoring wells may be sidegradient, notdowngradient from the Sta-Rite property. Unfortunately, a groundwater samplingprogram was not implemented to test this model and aid with the completecharacterization of contaminated groundwater moving away from the Sta-RitePlant 2.

      While groundwater contamination beneath Sta-Rite Plant 1 may be hydraulicallyisolated from Well No. 4, there is a contaminant plume migrating away from this areaof the Sta-Rite property and the extent of this plume has not been determined. Furthermore, it has not been determined if there is a downgradient merging of thecontaminant plumes flowing from Plant 1 and Plant 2.

      Piecing together a clear picture of contaminated groundwater in the Delavan area isfurther confounded by the detection of site-related contaminants in manygroundwater monitoring locations, including those which are apparently upgradientfrom Sta-Rite. The full extent of contaminated groundwater beneath and near Delavan has not been determined.

  6. The author makes reference to the Delavan School for the Deaf. Since when has thehandicap of being deaf increased the sensitivity to contaminated groundwater?
      Many students at the School for the Deaf were reported to have multiple handicapsand related health problems [19]. Some studies report that people with pre-existinghealth problems may be more susceptible to the effects of certain substances. Peoplewith compromised kidney or liver functions may have an increased risk of the toxiceffects of TCE or PCE since the liver serves as the primary site of PCE and TCEmetabolysis, with their metabolites excreted through the kidney [2][3].


This Delavan Well No. 4 Public Health Assessment was prepared by the Wisconsin Departmentof Health and Family Services under a cooperative agreement with the Agency for ToxicSubstances and Disease Registry (ATSDR). It is in accordance with approved methodology andprocedures existing at the time the public health assessment was begun.

Gail D. Godfrey
Technical Project Officer
Superfund Site Assessment Branch (SSAB)
Division of Health Assessment and Consultation (DHAC)

The Division of Health Assessment and Consultation, ATSDR, has reviewed this public healthassessment and concurs with its findings.

Richard E. Gillig

Table of Contents The U.S. Government's Official Web PortalDepartment of Health and Human Services
Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

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