V & L STRIPPING
GREEN BAY, BROWN COUNTY, WISCONSIN
The Wisconsin Department of Health and Family Services (DHFS) was contacted byrepresentatives of the former V & L Stripping Property in Green Bay, Wisconsin, with arequest for assistance in evaluating the vapor intrusion exposure pathway at the site. Afterreviewing the existing remedial investigation results, DHFS recommended the collection ofadditional environmental data, and then assisted with the collection of that data. This publichealth consultation provides a summary of the investigation results and DHFS follow-uprecommendations.
The site poses an indeterminate public health hazard for past, current, and future exposures. The results of those samples indicate that a vapor intrusion potential does exist for theproperty east of the business. Based on the sub-slab sample taken from a near-by MatherStreet residence, it is unlikely that the pathway could be ruled out for this residence withoutactive mitigation. Active remediation of the contaminant source area should also be conducted to reduce the low potential for contaminated soil vapor migration.
The V&L Stripping site, also known as the Ken Juza property, is a former dry cleaningbusiness with previously confirmed groundwater and soil contamination. The primarycontaminants of concern are chlorinated solvents including tetrachloroethylene,trichloroethylene, and other related contaminants. Based on Wisconsin Department ofNatural Resources (DNR) review of the groundwater and soil investigation, some sourceremediation will be needed at the site. After reviewing the site investigation data for soils andgroundwater at this site, DHFS and DNR recommended additional sampling in June 2003 tobetter characterize the vapor intrusion pathway from the site to nearby residences.
On June 19, 2003, the contractor for the responsible party and staff from DHFS collected foursamples to evaluate the vapor intrusion migration pathway at the V&L Stripping property,864 Mather Street, Green Bay, Wisconsin. The samples were collected from (1) the ambientair on the property, (2) the soil vapor probe installed by Northern Environmental across thealley from the site, (3) sub-slab soil vapor beneath the basement of the adjacent residentialproperty, and (4) basement indoor air of the adjacent residential property. The samples werecollected in six liter, evacuated stainless steel canisters. Each sample was analyzed for volatileorganic compounds (VOCs) at the State Laboratory of Hygiene using EPA method TO-14. The results of the analysis are summarized in Table 1. Photographs of the sample collectionfor each sample are at the end of this document (Figures 1 to 4).
The ambient air sample (outdoor air) was collected as a reference because ambient air quality can have an effect on the air quality of each of the other samples. This sample was located behind the building on the northeastern part of the property (864 Mather). Analysis of this sample identified low concentrations of a number of VOCs including acetylene, benzene, carbon tetrachloride, propene, toluene, and xylenes. The benzene and carbon tetrachloride levels are slightly above the health-based comparison values included in Table 1. These levels are consistent with our knowledge of ambient air quality around the state.(1),(2) Although we do not have health based comparison values for acetylene and propene, the levels detected in these samples do not indicate exposures of health significance. The primary contaminant of interest, tetrachloroethylene, was not detected in the ambient air sample.
The soil vapor sample was collected from the back yard of the residence north of the site. This sample was collected to determine whether site related contaminants in soil vapor were migrating in soil vapor towards residential properties north and northeast. The soil vapor sample contained tetrachloroethylene and a low-level detection of chloroform. Chloroform has not been found as a contaminant of concern in the past at the site. It is not clear if the chloroform detected is from degradation of site contaminants or from another source. The tetrachloroethylene detected indicates some soil vapor migration from the site.
|VOC||Ambient Air||Soil Vapord||Sub-Slab Vapord||Basement Indoor Air||Comparison Value (EPA)|
(EPA) -from Table 2c of EPA Draft Guidance for Evalutating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils
All units - parts per billion by volume (ppbv)
ND - Chemical Not Detected
NA - Comparison Value Not Available
d - Results approximate due to dilution technique
Concentrations below the comparison values shown in Table 1 are not likely to be of health concern under most common circumstances. Chemical concentrations in indoor air above those levels are not necessarily a health hazard, but warrant a closer evaluation. Although both chemicals exceeded their respective health-based comparison values, these concentrations are not relevant to public health because they were not measured at a point of possible exposure.
The sub-slab sample taken beneath the basement at the near-by residence contained a relatively high level of tetrachloroethylene along with methylene chloride and toluene. The purpose of the sub-slab sample was to determine if contaminants had migrated from the source area to the foundation of the adjacent building. Because the contaminant source area in soil is close to the residence, we did not expect to find a clean soil vapor sample between them. The tetrachloroethylene result indicates that contaminants do migrate from the source area to the foundation of this home. The source of the methylene chloride and toluene detections is less clear, because the concentrations of each were considerably higher in the corresponding indoor air sample.
The results of the indoor air sample from the residence show a variety of VOCs, which could have originated from ambient air, soil vapor, and indoor sources. This sample was collected for comparison to the sub-slab sample result. Because of the variability of indoor air quality as it relates to vapor intrusion, this sample is of limited use in making decisions for the site. Of the fifteen chemicals detected, only the tetrachloroethylene in this sample is plausibly linked to a soil vapor source. However, there are potential household sources of tetrachloroethylene that cannot be ruled out as a source for this sample. It is important to note that this indoor air sample was a short-term (grab) sample that is not likely to be representative of long-term air quality in the basement, and even less predictive of long-term air quality in the living area of the home. The sub-slab conditions are expected to remain more consistent over time and, as such, are a better predictor of the vapor intrusion pathway.
As is common with air sampling, there were a variety of chemicals detected that are unrelated to the contaminant source area at the site. The sample from the basement indoor air contains numerous chemicals that could have come from several containers of chemicals on the basement shelves. The concentrations of the various chemicals are low, and the containers and storage area were in generally good condition. Removing these chemicals from the home may provide a small improvement in indoor air quality. (See Figure 5)
Both the soil vapor and sub-slab sample indicate that tetrachloroethylene from the site is available for off-site vapor intrusion. Neither the ambient air sample nor the basement indoor air sample indicated a source of tetrachloroethylene that could otherwise explain these results.
EPA, in its draft vapor intrusion guidance, assumes a minimum attenuation factor of tenfor shallow soil vapor migrating to indoor air. This means that a sub-slab measurement of670 ppbv is expected to result in an indoor air concentration no greater than 67 ppbvunder worst case conditions.(4) Although data from a number of sites evaluated by EPAindicate that the attenuation factor is likely much higher (leading to lower indoor airconcentrations), the measured sub-slab concentration at this site would not allow us to ruleout the vapor intrusion pathway without extensive and long-term monitoring of bothindoor air and soil vapor.
The short-term basement indoor air sample contained tetrachloroethylene at 0.12 ppbv. This result indicates, with limited confidence, that currently, there is no strong tendencytowards vapor intrusion into the home. The sample was taken over a short period duringthe summer months when fresh air exchange is greatest, and the influence of a stack effectwould be largely absent. Levels could be higher during winter months when fresh airexchange is minimized.
The lower level of tetrachloroethylene found in the soil vapor sample from the locationacross the alley is also higher than EPA's screening values for tetrachloroethylene inshallow soil vapor. However, the tetrachloroethylene concentration is much lower, andadditional characterization could allow us to rule out the pathway on this property.
The remediation of the source area of the site should have an effect on soil vapor andshallow groundwater contaminant concentrations. If remediation of the source area takesplace, additional sampling resources related to the property across the alley would bebetter spent on confirmation sampling to ensure that the action is effectively controllingoff-site migration.
Daily exposures for many years to high concentrations of tetrachloroethylene (such as in anoccupational setting) can result in liver and kidney damage and may result in an increased risk of developing some forms of cancer.(5) Long-term exposure to tetrachloroethylene levelsrelevant to what could be found at this site are not likely to result in an increase in non-cancerhealth problems. However, tetrachloroethylene is classified as a possible human carcinogen. Even though cancer risks are low, DHFS considers exposure unnecessary and prudent toavoid.
Long-term exposure to chlorinated solvents and other volatile organic compounds inindoor air is a risk to child health. Although levels that might impact homes with children are low, exposure should be avoided if possible.
- Tetrachloroethylene from the V&L Stripping site impacts soil vapor on two neighboring residential properties.
- On-going exposure poses an indeterminate public health hazard. Existing data were collected during summer months. Levels in the indoor air could be higher, at levels of concern, during winter months.
- Remediation of the source area on the site would likely lower the risk of off-site vapor migration.
- It is unlikely that additional investigation would allow us to rule out vapor intrusion as a source of human exposure at the nearby residence where low levels of tetrachloroethylene were found.
- The soil vapor sample collected at the residence across the alley indicates a very low potential for vapor intrusion into the home on that property. Additional sampling may rule out this pathway. Remediation of the source area may also result in eliminating this potential migration pathway.
- The adjacent property owners and occupants should be advised of the results of thissampling.
- The remedial action should be monitored for its effectiveness at source removal andcontrol of off-site soil vapor migration.
- Because of the high tetrachloroethylene concentrations in the sub-slab soil vapor at thenear-by residence, DHFS recommends mitigating possible exposures, such as throughthe installation of a sub-slab depressurization system by an approved radon mitigationcontractor. DHFS recommends that any exposure mitigation action, such asinstallation of a sub-slab depressurization system, be done no later than November 30,2003, because levels could increase during winter months.
- DHFS will provide a copy of the Vapor Intrusion fact sheet to residents along withletters describing the sample results for their properties in detail.
- DNR and the responsible party have agreed in principle to monitor the effectiveness ofsource removal and control of vapor migration.
- DNR and responsible party have agreed in principle to install a sub-slabdepressurization system at the residence where tetrachloroethylene was found in indoorair, and DNR has included this recommendation as a condition of approval for theremedial action workplan.
- DHFS will advise residents on the importance of proper storage of household chemicals,and respond to questions and concerns from nearby residents as they arise in thefuture.
- DHFS will follow-up on the last three recommendations in January of 2004 to makesure that these recommendations to reduce exposure potential have been followed.
Wisconsin Department of Health and Family Services
Bureau of Environmental Health
This public health consultation on the V&L Stripping Site was prepared by the Wisconsin Department of Health and Family Services under a cooperative agreement with the Agency for Toxic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the public health consultation was begun.
Technical Project Officer, SPS, SSAB, DHAC
The Division of Health Assessment and Consultation, ATSDR, has reviewed this public health consultation and concurs with the findings.
Chief, SPS, SSAB, DHAC, ATSDR
1 DNR. "Wisconsin Urban Air Toxics Monitoring - A Summary Report for the Period. July 1997 - June 1998
2 DNR. "Results of Air Monitoring in Eagle River". April 6, 2000.
3 Wisconsin State Lab of Hiegiene, Laboratory Reports for Labslip numbers ON002545-8. Reported July 18, 2003.
4 USEPA. "Draft Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway from Groundwater and Soils (Subsurface Vapor Intrusion Guidance)." November, 2002. http://www.epa.gov/correctiveaction/eis/vapor.htm
5 ATSDR. "Toxicological Profile for Tetrachloroethylene". September,1997. http://www.atsdr.cdc.gov/toxprofiles/tp18.html