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HEALTH CONSULTATION

BAY CITY AIRPORT
BAY CITY, BAY COUNTY, MICHIGAN

DISCUSSION

The Bay City government has proposed to develop a boat launching ramp on the BCA property (1). The individuals with the most exposure to the environmental media on the property would be attendants working there, if any. People using the boat launch would most likely spend short periods of time on the property and visit it only occasionally. To determine whether further toxicological evaluation is necessary, the concentrations of chemicals found on the property will be compared with the MDEQ Generic Clean-up Criteria for Industrial or Commercial Use (3).

During the BFRA, MDEQ staff collected 25 samples of surface soil from the BCA property, in a sampling gridwork drawn across the entire parcel area. None of the samples contained any chemical at a concentration above the MDEQ Generic Clean-up Criteria for Industrial or Commercial Use (Table 1) (2, 3).

MDEQ staff also collected 13 samples of subsurface soil from the BCA property, from locations on a similar gridwork across the entire parcel. Again, none of the samples contained any chemical at a concentration above the MDEQ Generic Industrial/Commercial Criteria (Table 2) (2, 3).

In 1988, the Michigan Department of Natural Resources (MDNR)¹ Surface Water Quality Division collected sediment samples from the Saginaw River, from the city of Saginaw (south and upstream of Bay City) to the mouth (north of Bay City), and from Saginaw Bay, and analyzed the samples for polychlorinated biphenyls (PCBs). A sample collected from the main channel of the river near the BCA property contained 0.050 parts per million (ppm) PCBs (5).

During the BFRA, MDEQ staff collected 12 samples of sediment from water bodies adjacent to the BCA property, four each from the Saginaw River just offshore, the creek on the north side of the property, and the canal on the east side. None of these samples contained any chemicals at concentrations above the MDEQ Generic Industrial/Commercial Criteria or any PCBs above the detection limit (Table 3) (2, 3).

The Saginaw River has had a history of PCB contamination in the sediment, surface water, and biota, because of industrial activities in the River's basin (5, 6, 7). The MDCH has issued an advisory that people should not consume any carp or catfish taken from the Saginaw or Tittabawassee Rivers, and that they should limit their consumption of fish of any species taken from either river, due to contamination with PCBs and dioxins (8). The PCB concentrations in Saginaw River sediment near the BCA property would not be considered to pose a health threat from direct contact even if the sediments were on shore, where contact might be much more frequent.² A person using the river for recreation is not likely to drink enough water from the Saginaw River to incur any significant increased cancer risk from the PCBs in the water. No PCBs were found in any medium on the BCA property sampled during the BFRA (2).

During the BFRA, MDEQ staff collected unfiltered groundwater samples from 5 temporary monitoring wells on the BCA property, four located along the Saginaw River bank on the west side of the property and one in the center of the property. At least one of these samples contained antimony, beryllium, chromium, cobalt, lead, manganese, methylene chloride, nickel, or vanadium at a concentration above the MDEQ/U.S. EPA health-based drinking water standards (Table 4) (2, 4). The highest concentrations of the above-named metals were found in the sample from the center of the property. All five samples contained 5 parts per billion (ppb) methylene chloride, equal to the MDEQ/U.S. EPA drinking water standard. The chemical is a common laboratory contaminant. None of the chemicals is present in the water at a concentration that would pose a health hazard by direct contact or by inhalation after volatilization to indoor air during household use of the water (9). There is no known current use of the groundwater at the property. The available information does not identify the direction of the groundwater flow at the property. However, because the property borders on the Saginaw River, it is most likely that the groundwater flows directly into the river. There are no wells between the property and the river.

The BCA property itself poses no physical hazards. Drums and abandoned storage tanks have been seen in the wooded area north of the property, which is privately owned. There is no fence between the BCA property and the wooded area. Vehicle access to the BCA property is via a two-track path across the wooded area north to 41st Street, at which point there's a gated fence. However, there is a foot path into the wooded area from the east, which crosses the canal on a makeshift bridge.

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