GROUNDWATER - RESIDENTIAL WELLS
BENDIX CORPORATION/ALLIED AUTOMOTIVE
ST. JOSEPH, BERRIEN COUNTY, MICHIGAN
The sampling results discussed in this consultation were taken from the available investigations of the property, and are not adjusted for limitations or bias in the sampling programs. The Tables presented in this consultation include maximum and median concentrations in the samples collected. Health discussions are based on the maximum concentrations reported and long-term, frequent exposure scenarios, reasonably conservative assumptions. We compared the amounts actually or potentially ingested with laboratory data on a body weight basis.
Anyone using the groundwater in the plume is likely to be exposed to several chemicals simultaneously. When more than one chemical is present in the body, the chemicals may interact so that the effects of the combined dose are equal to the sum of the effects of each chemical independently, the total effect is increased over the sum, or the total effect is decreased. Such interactions are not well understood, and there is little information to permit an evaluation of the probabilities and effects of such interactions in the area of the Bendix site. The toxicological discussions below do not consider the effects of interactions between the chemicals.
RW-1 is the closest active residential well to the contaminant plume, and is the only one which has been confirmed as containing contaminants at concentrations above the U.S. EPA Maximum Contaminant Levels (MCLs)(2) (trichloroethylene and vinyl chloride). Until recently, the well was used only for lawn watering, because the house it serves was connected to the municipal (St. Joseph city) water system in April 1984 (9). The owner has reportedly accepted an offer from Bosch Braking Systems to permanently abandon the well. RW-2 is the only residential well that was sampled that is still used to supply household water for all uses. The house served by RW-3 was connected to the municipal water system in August 1988, and the well is not being used. Well RW-4 was used for all household purposes until April 1994, when the house it served was abandoned. Part of the house the well had served had collapsed into Lake Michigan because of beach erosion. RW-5 is only used for lawn watering, and the house it serves was connected to the municipal water system in March 1991 (8, 9, 10). According to the well-use survey carried out by Bosch Braking Systems in August 1997, other houses along Lake Bluff Terrace were connected to the municipal water system between 1972 and 1978. The residents of four of these houses reported to Bosch that they had inactive private wells. One Lake Bluff Terrace address was connected to the municipal water system as late as May 1996, according to St. Joseph city records, though the residents reported to Bosch that the residence had never had a private well since it was constructed in 1985 or '86. A residence with a Lakeshore Drive address just north of Lake Bluff Terrace was connected to the municipal water system in July 1984, and they still have an inactive private well (RW-6) that has never been sampled. Most of the land between Lakeshore Drive and the lake and between Lake Bluff Terrace and RW-5 is undeveloped (8, 10).
The people using RW-1, the one residential well that has contained contamination above the MCLs, had their house connected to the municipal water system as late as April 1984, and a water sample collected from their well in October 1984 contained VOC contamination at high levels (Table 3). It seems likely that the people using the well were drinking and washing with VOC-contaminated water before they switched to the municipal water supply. The household formerly served by the inactive RW-6, located further inside the contaminant plume than RW-1, connected their residence to the municipal water system even later, in July 1984 (8, 10). RW-6 has never been tested, though water collected from a monitoring well on property between RW-1 and theirs (OW-29) in March 1985 contained as much as 9,950 ppb of five VOC contaminants of concern (1,1-dichloroethane, 1,2-dichloroethane, trans-1,2-dichloroethylene, trichloroethylene, and vinyl chloride) (3).
The durations of the potential exposure for the residents of the Lake Bluff Terrace neighborhood are not known. We know when they started using municipal water, from the residents' own reports and St. Joseph city records. However, there is no information available on when the VOCs first migrated into the groundwater in the neighborhood. The first collections of groundwater samples, in 1984 and 1985, found a well-established plume of contamination already under the neighborhood. The Bendix lagoons were in use from approximately 1953 through 1975, but official Bendix records do not indicate that VOCs were disposed of in the lagoons. There are rumors and allegations that the wastes did include "organic solvents" potentially including VOCs. There is also some uncertainty over whether the lagoons are the sole source for the contamination.
From the plume extent (10 ppm total 1,2-dichloroethylene, trichloroethylene, and vinyl chloride) measured in March 1985, the groundwater surface gradient measured in 1990, and the hydraulic conductivities determined during the 1985 Keck hydrogeological study, we have estimated that the leading edge of the plume might have crossed Lakeshore Drive before 1958. Measurements in September 1988 indicated that the leading edge of the plume had apparently receded since 1985, though it had moved onward again by January 1990 (2, 3). Based on these estimates, it seems likely that people living along and north of Lake Bluff Terrace were exposed to groundwater contaminated with VOCs during the time before their residences were connected to the municipal water supply. However, it is not possible to establish with any confidence the exposure doses they experienced or the duration of their exposure.
Currently, no private well in the area with any history of contamination above MCLs supplies water for household use. Based on the available data on VOC concentrations in residential wells, no one is likely to ingest as much of any of the chemicals as has been observed to cause adverse health effects in humans or laboratory animals at any exposure duration. Vinyl chloride is a known human carcinogen (U.S. EPA Class A), and 1,2-dichloroethane and trichloroethylene are probable human carcinogens (1,2-dichloroethane is U.S. EPA Class B2. The U.S. EPA has withdrawn its classification of B2 for trichloroethylene to reevaluate the data) (11, 12, 13). Lifetime use of water containing the concentrations of the three carcinogens found in the residential wells might result in a low increased risk of contracting cancer.
Only five private wells in the endangered area have ever been sampled. Several residences in the area who currently use municipal water have inactive private wells on their property. The owners of these inactive wells pulled them out of service before the first studies of the groundwater in the neighborhood were conducted, one (RW-6) three months before. There is no record that any of these inactive wells were ever sampled. We will evaluate the potential human health hazard through these wells assuming the maximum concentrations found in monitoring wells in the northwest plume area (Table 1).
No one is likely to ingest enough 1,1-dichloroethane from the groundwater in the northwest plume area to exceed the amounts that were observed to cause adverse health effects in humans or laboratory animals at any exposure duration. Some laboratory animals who ate food containing large amounts of the chemical developed more cancers of the breast, uterus, or blood vessels than did those whose feed did not contain the chemical. The U.S. EPA has classified the chemical as a possible human carcinogen (U.S. EPA Class C). There is not sufficient information available about the chemical to evaluate the potential risk of contracting cancer upon exposure to it (14).
No one is likely to ingest enough 1,2-dichloroethane from the groundwater in the northwest plume area to exceed the amounts that were observed to cause adverse health effects in humans or laboratory animals at any exposure duration. Lifetime consumption of the groundwater might result in an moderately increased risk of contracting cancer (11).
No one is likely to ingest enough 1,1-dichloroethylene from the groundwater in the northwest plume area to exceed the amounts that were observed to cause adverse health effects in humans or laboratory animals. Some laboratory animals who breathed air or ate food containing large amounts of the chemical developed increased numbers of cancers of the kidneys and other organs. The U.S. EPA has classified 1,1-dichloroethylene as a possible human carcinogen (U.S. EPA Class C). Lifetime consumption of the groundwater might result in an moderately increased risk of contracting cancer (15).
No one is likely to ingest enough 1,2-dichloroethylene from the groundwater in the northwest plume area to exceed the amounts that were observed to cause adverse health effects in humans or laboratory animals at any exposure duration. Exposure to 1,2-dichloroethylene has not been linked to cancer in humans or animals (16).
Anyone whose drinking water contains the maximum concentration of trichloroethylene found in monitoring wells in the northwest plume area (Table 1) might ingest more of the chemical than did rats whose offspring had heart abnormalities after long-term exposure in a laboratory study. No one would be likely to ingest enough trichloroethylene from the groundwater to exceed the amounts fed to laboratory animals who developed cancer. Some laboratory animals who inhaled or ingested trichloroethylene developed elevated rates of cancers of the livers or kidneys. The U.S. EPA had classified trichloroethylene as a probable human carcinogen (U.S. EPA Class B2), though the Agency is reconsidering the classification. Lifetime consumption of the groundwater might result in a moderately increased risk of contracting cancer (12).
Anyone whose drinking water contains the maximum concentration of vinyl chloride found in monitoring wells in the northwest plume area (Table 1) might ingest more of the chemical than did rats who developed liver problems after long-term exposure in a laboratory study. A child using similar water might ingest more of the chemical than did rats who developed an increased incidence of liver cancer after long-term exposure in a laboratory study. No studies could be located that document and quantify health effects in humans after ingestion exposure to vinyl chloride. Lifetime consumption of the groundwater might result in a very high increased cancer risk (13).
The plume discharges into Lake Michigan. This has raised some question of whether it is safe to swim or otherwise recreate in the lake or on the beach near where the groundwater discharges. Water samples collected from the lake in the area have not contained any contamination at the limits of detection for the analytical techniques (17). In the case of children digging into the groundwater on the beach, the maximum vinyl chloride concentration in the water, from every monitoring well sampling event listed in Table 1, exceeded the MDEQ Interim Groundwater Contact Criteria(3) (18). None of the residential well samples has contained vinyl chloride or any other chemical above the Contact Criteria. VOCs evaporating from the ground water are likely to disperse as soon as they reach the open air, and not reach concentrations of human health concern.
The concentration of vinyl chloride in the air in a shower using groundwater from the area, based on the maximum concentration found, from OW-29 in March 1985 (Table 1), might exceed the levels that caused changes to the liver and heart and cancer in laboratory animals who breathed air containing the chemical for long periods (over 1 year). The vinyl chloride concentration in the air of a shower using water from RW-1 (Table 3) would not reach the levels at which adverse health effects were observed, though a lifetime breathing air containing that concentration of the chemical might result in a moderate increased risk of contracting cancer (13, 19).
It is possible that VOCs in the groundwater could volatilize in the soil, migrate upward into a basement in the residential area, and there collect to levels of potential human health impact. The concentrations of 1,2-dichloroethane, trans-1,2-dichloroethylene, trichloroethylene, and vinyl chloride found in groundwater under the residential area along Lake Bluff Terrace (Table 1) exceed MDEQ screening criteria for exposure in residences from groundwater volatilization to indoor air (18). However, the groundwater in the area is thirty feet or more below the surface (3), therefore there is little likelihood that the groundwater would enter a basement of typical depth, and the volatilized VOCs are likely to disperse and diffuse to much lower concentrations before they near the surface.