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The Environmental Protection Agency (EPA) Region 10 asked the Agency for Toxic Substances and Disease Registry (ATSDR) to review environmental data provided by the current owners of the former Franke's Laundromat site in Caldwell, Idaho. The review is to determine the public health implications and to provide recommendations on future site removal action.

The former laundromat site (the site) is in a commercial and industrial area of downtown Caldwell. The site consist of an unoccupied, single-story building, an asphalt paved parking lot, and a gravel parking area. The building was used as a laundromat and dry cleaning facility from the early 1960s until early 2000. Structures surrounding the site include the City of Caldwell Police station, several small businesses, and a trailer park [1].

Since 1999, the property owners and the City of Caldwell have performed site investigations and discovered tetrachloroethene (PCE) in the soil and groundwater [1-2]:

  • In April 1999, the property owners performed a "limited environmental assessment," and the maximum PCE concentration in groundwater onsite was 12.1 micrograms per liter (µg/L);
  • In March 2000, the City of Caldwell conducted a "limited phase II site assessment." At that time, the maximum PCE concentration in groundwater onsite was 47,000 µg/L;
  • July 2003, a contractor collected soil, groundwater, and soil vapor samples to characterize fully the lateral and vertical extent of PCE contamination. This health consultation will review available environmental data from this site investigation.


The primary route of human exposure to PCE related to this site is inhalation of contaminated indoor air through possible vapor intrusion. Ingestion exposure (drinking water) and inhalation exposure from indoor water use are also of concern if the PCE plume expands and impacts any potable water sources.

Three soil vapor samples were taken off-site at a paved area outside a commercial building (a printing shop) across the street from the site. Because limited samples from a single location may not be representative for the entire impacted area, additional samples are necessary to fully characterize the contamination.

Nonetheless, all three soil vapor samples detected PCE, with a maximum level of 93,900 µg/m3 at a depth of 4-5 ft below ground surface (bgs). Soil conditions and building construction may attenuate soil vapor concentrations migrating into indoor air. A very rough estimate of the indoor air concentrations may be 10 to 100 times less than the soil vapor concentrations. For example, using a conservative soil vapor to indoor air attenuation factor of 10, EPA's draft subsurface vapor intrusion guidance suggests that a PCE shallow (sampling depth <5 ft bgs) soil vapor concentration of 810 µg/m3 represents an estimated target indoor air PCE concentration of 81 µg/m3. In the case of the current site, the detected PCE soil vapor concentration was 93,900 µg/m3, suggesting an estimated indoor air concentration range of 939 to 9,390 µg/m3.

Soil vapors can enter residences and other buildings through preferential pathways–preferred flowpaths such as foundation cracks and gaps, mechanical ventilation systems, paleochannels–and leakage areas (for example, utility entry points, construction joints, and drainage systems). The preferred flowpaths tend to contain rather than disperse the contaminated groundwater. In recent years, soil vapor sampling data have been used to qualify and/or quantify indoor air risk through modeling. However, the levels of soil vapor are affected by many factors, such as water and air movements, temperature variations in soil and atmosphere, molecular diffusion, biodegradation, barometric pressure, precipitation, building structures, and pressure differences between the inside and outside of buildings [3-7].

ATSDR used the Johnson and Ettinger Model to further refine the estimate of the indoor air concentration of PCE from the maximum groundwater concentration. The model was based on a number of simplifying assumptions regarding contaminant distribution and occurrence, subsurface characteristics, transport mechanisms, and building construction. The model was used only as a screening tool to identify conditions that may warrant additional evaluation [8-9]. The model calculated an indoor air PCE concentration of 823 µg/m3. The calculated levels from the model would be of public health concern if the vapor were to enter occupied buildings. While the building onsite currently remains unoccupied, it may become occupied in the future.

Respirable indoor air contaminant concentrations are also not measured in soil vapor monitoring and modeling results. The best approach to evaluate air contamination at points of exposure would be to measure directly the indoor air quality in potentially impacted buildings. No direct indoor air samples, however, were available for this evaluation.

An ambient air sample taken at the same location showed a PCE concentration of 1,700 µg/m3, and information was insufficient to determine the quality assurance (QA)/quality control (QC) as well as any potential cross contamination of the sample. However, the detected level is a public health hazard if it represents actual human exposure through inhalation. The ATSDR acute and chronic the environmental media evaluation guides (EMEG) for PCE are 1356 and 271 µg/m3, respectively. EMEGs are concentrations of PCE in air that are unlikely to be associated with any appreciable risk of deleterious non-cancer effects over a specified duration of exposure. Again, more data are needed to verify PCE concentrations.

Groundwater results were available for a total of 37 groundwater samples taken from 15 monitoring wells (MW). Most of the samples were collected in the clay zone (9-17 ft bgs). The maximum PCE concentrations were 154,800 µg/L (MW 11) for onsite locations and 1,200 µg/L for offsite locations at the shallow aquifer. Four samples were taken for the deeper aquifer, but only two samples (MW 15) results were available for review. Sampling depths for two samples taken from MW 18 were not available although the well was constructed to reach the lower aquifer. ATSDR's chronic EMEG for PCE in drinking water is 400 µg/L.

To date, no known domestic drinking water wells have been affected. The extent of the PCE plume not yet defined, however, and PCE in the shallow aquifer may migrate into the lower aquifer. It should also be noted that 1) PCE can biodegrade and form more toxic compounds such as trichloroethene and vinyl chloride at a much lower concentration; 2) high PCE concentrations can mask the detection of those metabolites at low concentrations; and 3) PCE contaminated groundwater may move via preferred flowpaths and carry the contaminants further away from the source without reducing the contaminants' concentrations significantly.

A total of 43 soil samples were taken both onsite and offsite. The maximum PCE concentrations were 450 milligram per kilogram (mg/kg) for onsite locations. The EPA region 9 preliminary remediation goal (PRG) for PCE in industrial soil is 3.4 mg/kg. PCE's chemical and physical characteristics and its high concentration in the soil at this site suggest that PCE may be an on-going source of soil vapor intrusion into buildings and may affect local groundwater. Removal and/or remediation of the PCE source would minimize the potential impact of PCE on human exposure from soil, soil vapor, groundwater, and ambient air. Removal/remediation would also minimize potential future exposure to more toxic "daughter" products of biodegedation such as trichloroethylene and vinyl chloride.


In evaluating health effects from the site-specific environmental exposures at the site, children were considered as a special population because of 1) children weigh less than adults, resulting in higher doses of chemical exposures relative to body weight, 2) children have higher rates of respiration, 3) metabolism and detoxification mechanisms differ in both the very young and very old and may increase or decrease susceptibility, and 4) the developing body systems of children can sustain permanent damage if toxic exposures occur during critical growth stages. ATSDR has considered these factors in the development of conclusions and recommendations for this site. If the calculated PCE levels from the model actually exists for indoor air, a public health concern would exist for children.


The PCE contamination at the former Franke's Laundromat has not been fully characterized. The available data are not sufficient to eliminate potential human exposure to PCE and its daughter products via inhalation of contaminated soil vapors for current workers in nearby buildings or for any future occupants of buildings constructed on-site or nearby. Modeling indicates that future occupants of on-site buildings (current or new buildings) could be exposed to PCE and its daughter products via inhalation of soil vapors at concentrations that may be harmful over prolonged periods.

Information on all current and future users of down-gradient groundwater is also needed to determine whether people may be ingesting harmful levels of PCE and its daughter products now or in the future.

Available environmental data are insufficient to eliminate human exposure pathways through potential soil vapor intrusion and drinking water contamination. ATSDR categorizes this site as an indeterminate public health hazard.

The measured PCE level of 1,700 µg/m3 in an ambient air sample indicates a public health hazard if it represents actual human exposure through inhalation.


Complete site characterization to define adequately the potential for off-site human exposures via inhalation of contaminated indoor air and ingestion of contaminated groundwater.

Prevent exposure to PCE and its daughter products via inhalation for any future occupants of on-site buildings. Prevention methods include the on-site remediation proposed by EPA.


  1. US Environmental Protection Agency. Action Memorandum: Request for approval of time-critical removal action at Frank's Laundromat, Caldwell, Idaho. Boise, Idaho: US EPA (Region 10); 2003.

  2. HDR Engineering, Inc. Preliminary draft removal site investigation report, former Franke's Laundromat. Boise, Idaho, 2003.

  3. US Environmental Protection Agency. Draft guidance for evaluating the vapor intrusion to indoor air pathway from groundwater and soils (Subsurface vapor intrusion guidance). Washington, DC: EPA Office of Solid Waste and Emergency Response; 2002.

  4. Agency for Toxic Substances and Disease Registry. Landfill Gas Primer–an overview for environmental health professionals. Atlanta: US Department of Health and Human Services; 2001.

  5. Cohen Y, Volatile organic compounds in the environment: a multimedia perspective, volatile organic compounds in the environment. ASTM STP 1261, W Wang, J Schnoor, and J Doi, eds. American Society for Testing and Materials, Philadelphia, pp. 7-32, 1996..

  6. Kildiff JK and Cody RJ Soil vapor concentration profile: approximate solutions to aid sampling design and indoor air risk assessment. The third international conference on the remediation of chlorinated and recalcitrant compounds. Monterey, California. May 20-30, 2002.

  7. Doa MJ, The toxic release inventory. Journal of hazardous waster & hazardous materials. 9:61-72. 1992.

  8. Marley MC, et al. Soil vapor sampling and modeling for indoor air risk characterization. The third international conference on the remediation of chlorinated and recalcitrant compounds. Monterey, California. May 20-30, 2002.

  9. US Environmental Protection Agency. User's Guide for evaluating subsurface vapor intrusion into buildings. Office of emergency and remedial response. Washington, DC: US EPA, 2003.


Jane Zhu, MPH
Environmental Health Scientist
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

Reviewer of Report:

Don Joe
Exposure Investigations and Consultations Branch
Division of Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry

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