HEALTH CONSULTATION
CONRAIL-JACKSON YARD
JACKSON, MICHIGAN
During an EPA-sponsored inspection of the CJY in July 1987, the contractor collected 8 samples of surface soil from the property. The lead concentration in most samples exceeded the MDEQ Generic Clean-Up Criteria for Residential, Industrial, and Commercial Use3, and the arsenic, benzo(a)pyrene, benzo(b)fluoranthene, or dibenz(a,h)anthracene concentrations in several samples exceeded the MDEQ Clean-Up Criteria for Residential Use (Table 2) (5, 6).
No significant pattern exists to the distribution of elevated concentrations of chemicals mentioned in the previous paragraph. The highest concentrations of arsenic, benzo(a)pyrene, and benzo(b)fluoranthene were all in one sample from the west side of the property. However, the highest concentrations of lead and dibenzo(a,h)anthracene were found in a different sample, collected from the site of a roundhouse in the southeast corner of the property. That sample also contained the second highest concentrations of the other chemicals mentioned, and the sample from the west side contained the fourth highest concentration of lead and no detectable dibenzo(a,h)anthracene. Contractors collected one sample from among the drums they'd seen on the property, and that sample contained concentrations of arsenic and lead that were elevated relative to the standards or backgrounds but were the fifth highest of arsenic and sixth highest of lead of all samples from the property. That sample contained no detectable benzo(a)pyrene, benzo(b)fluoranthene, or dibenz(a,h)anthracene (1).
During field work for an Integrated Assessment of the property in April 1997, the MDEQ collected 12 samples of surface soil from the property. The arsenic concentration in one sample and the lead concentration in another sample exceeded the respective MDEQ Generic Clean-Up Criteria for Industrial or Commercial Use (Table 2) (5). These two samples were both collected from the northwest corner of the property. All 12 surface soil samples contained arsenic at concentrations above the MDEQ Generic Clean-Up Criteria for Residential Use. The lead concentration in the one sample cited above and the benzo(a)pyrene concentrations in several samples from around buildings on the property also exceeded the MDEQ Residential Criteria (3, 6).
During the Integrated Assessment in April 1997, the MDEQ also collected 12 samples of subsurface soil from the property. Some samples contained arsenic and benzo(a)pyrene concentrations above the MDEQ Residential Use Criteria (Table 3). The highest arsenic concentrations were in the northwest corner of the property, the highest benzo(a)pyrene concentration in the southeast (3).
Results of these soil analyses indicate that the property does not pose any apparent health hazard for workers or occasional visitors such as customers.
During field work for the Integrated Assessment of the property in April 1997, the MDEQ installed 9 temporary shallow monitoring wells (water depths ranging from 4 feet to 16 feet below ground surface) on the CJY property. Water level measurements in the wells indicated that groundwater flow should be to the west. Samples of water collected from the wells contained no chemicals at concentrations that would pose a health risk from dermal contact (Table 4) (7). The concentrations of antimony, arsenic, lead, manganese, methylene chloride, phenanthrene, thallium, trichloroethylene, or zinc in some samples exceeded EPA or MDEQ drinking water levels (6). The highest concentrations of some chemicals were 10 times or more higher than the next higher concentrations. The highest concentrations of lead, phenanthrene, thallium, and zinc were found in water from one well in the northwest corner of the property, although concentrations above drinking water standards were found throughout the property. Trichloroethylene was found in only one well in the southeast corner of the property. The distribution of contaminant concentrations did not generally conform to single plumes, because concentrations on opposite ends of the property were often higher than those in the middle (3).
By city ordinance, residences within Jackson are to be connected to the municipal water system for their drinking water supply. Hence residents of the area west and south of the CJY property, likely downgradient to groundwater flow, are not generally exposed to groundwater contamination related to the property through their drinking water. Residents of the area might still have private wells, dating from before that ordinance was passed, which they use for lawn watering and other purposes. The ordinance also does not apply to industrial or commercial concerns, which might have private wells to supply their processes or for employee hygiene.
A search of City of Jackson Water Department files found two commercial operations approximately 0.5 miles southwest of the property that are not connected to the municipal system. Available records do not indicate the depths of wells serving these properties. In December 1993, water samples were collected from these private wells and analyzed for inorganic chemicals and VOCs. No inorganic chemicals were found at concentrations of health concern. The sample from one well contained traces (less than 1 part per billion [ppb]) of toluene (0.9 ppb), 1,2,4-trimethylbenzene (0.5 ppm), 1,3,5-trimethylbenzene (0.5 ppb), and xylenes (unquantified trace); a sample from the other showed no detectable VOCs. The MDPH judged that concentrations of VOCs posed no health concern for drinking or cooking (8). In November 1995, water samples were again collected from these wells and analyzed for VOCs in an investigation of the Jackson Drop Forge contamination site, approximately 0.5 miles south of the CJY property. No VOCs were detected (9, 10). Table 4 shows that xylene was found on the CJY property and in those private wells, and the concentration in the wells was much lower than that found on the property. Concentrations of toluene and trimethylbenzenes in the well cited were comparable to those in one well from Frogtown (Table 1), although the xylene concentration in the Frogtown well was much higher.
Contaminated groundwater on the CJY property was shallow enough that it might seep into a nearby basement. Although such an incident might bring residents into contact with contaminants, the occurrence would not likely be frequent enough for sufficient exposure to incur adverse health effects from direct contact, incidental ingestion, or inhalation of VOCs (7).
The City of Jackson municipal water system operates two well fields, the Mansion Street Field approximately 1 mile south-southwest and the Sharp Park Field approximately 2 miles southwest of the CJY property. City wells are screened in the Marshall and Saginaw bedrock formations, approximately 320 feet deep. For approximately 15 years, water from various wells in the Mansion Street Field has contained traces of cis-1,2-dichloroethylene. A combination of selective pumping, mixing with water from the uncontaminated Sharp Park Field, and quarterly sampling for VOCs keeps the cis-1,2-dichloroethylene concentration at an acceptable level in the finished water, below 1.5 parts per billion (ppb)4. The MDEQ regularly monitors all municipal water supplies in the state, with sampling for selected metals on a three-year cycle, and sampling for all metals on the EPA Total Analyte List every nine years (11). The Grand River, which likely provides a hydraulic barrier to groundwater floor, at least in the shallow aquifer, is between the CJY property and both City of Jackson well fields. The source of contamination in the Mansion Street well field has not been identified, but it is not thought to be related to the CJY property.
From 1993 to 1996, water from several residential wells, some as shallow as 20 feet below ground level, in the Frogtown community, northeast (and generally upgradient) of the CJY (see Figure 1 for location), contained benzene, trichloroethylene, or tetrachloroethylene at concentrations in excess of the MCLs (Table 1). The residents using these wells were given bottled water as soon as the contamination was confirmed. Construction of a water main to extend Jackson municipal water into the most highly contaminated areas of the community began in late September 1997 (4). Concentrations of chemicals in the water would not be sufficient to cause adverse non-cancer health effects, either by ingestion or by inhalation secondary to household use. Benzene, trichloroethylene, and tetrachloroethylene are all proven or probable human carcinogens (12, 13, 14). Even lifetime use of water containing the concentrations of those chemicals found in the water would not likely result in more than a slightly increased risk of developing cancer. In general, samples containing these chemicals were the first samples from the wells in the records, so no information is available on the total time of exposure. The documented times of exposure indicate that no one in Frogtown is likely to incur any apparent increased risk of developing cancer from contamination in the water. The source(s) of contamination in the Frogtown wells has not been identified, but it is not thought to be related to the CJY property.
A potential health hazard exists from groundwater contamination on the CJY property, but no known human exposure is occurring. Incidents of drinking water contamination in the Mansion Street well field and Frogtown do not appear to be associated with the CJY property except by proximity. The appropriate authorities are addressing these incidents.
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