Locations that were tested for total VOCs on Saturday, April 24 included: I-72 where the plume crossed the road; the road just south of the plant; Mechanicsburg; Buffalo and Lanesville; as well as on the plant property. During the two days following the explosion and fire, OER sampled on the plant property and around the entire perimeter. During that time, no chemical contamination was found at a level that would present a hazard for public health in the community.

When the initial readings showed total VOCs close to a worker safety level, a more chemical-specific piece of equipment was used – a Draeger system – which can test for the presence of vinyl chloride. This was used in two instances, on Cope Road and along I-72 in the smoke plume. The results for vinyl chloride were ten times less than the worker safety standard.

Hydrochloric acid gas (HCl), a by-product of burning vinyl chloride, was also monitored during the fire by CTEH, and no contamination levels were found in the air in the community. Nor did Illinois EPA’s OER observe the presence of HCl during the two days after the blast (even when staff was in the smoke plume), and HCl would produce obvious discomfort (e.g., burning of eyes, burning in lungs), if this chemical were present at even fairly low levels.

Vinyl chloride and other VOCs would not normally be found in “background” samples. However, the trace amounts of these site-related contaminants continue to be measured in the low parts per million range on the site, within federal air emissions standards. In the community, the measurements show no detectable amounts for vinyl chloride.

Full treatment resumed at the wastewater treatment plant on Saturday evening following the explosion and fire. The treatment plant continues to operate normally at a reduced load (since the plant is not in operation). Sample results to date have shown low concentrations of site related contaminants in the plant discharge, but no levels exceeding state criteria for human health or aquatic life protection have been found in downstream waters. Illinois EPA staff continue to monitor the treatment plant at least once per week.

Additionally, Illinois EPA staff, along with Illinois Department of Natural Resources biologists, made repeated observations of the stream macroinvertebrates (small bugs), fish, any odors or visible sheen both upstream and downstream from the site. To date, no apparent adverse effects were observed in the stream organisms. Illinois EPA will continue chemical sampling of the unnamed stream every other week and will perform a facility-related stream survey this summer, which includes chemical monitoring and a biological survey.

Dioxin may have been formed during the smoldering phases of the fire at the plant. A few initial samples were taken to test for dioxin on the site. Only one sample that was taken in sediments at the surface water outfall showed dioxin at a level (in parts per trillion) that is slightly greater than the U.S. EPA comparable background level used for screening. Based on the limited dioxin sampling done so far, Illinois EPA has determined that a more extensive sampling project (both on and off the site) is needed to define whether dioxin is present above background levels, and whether it is an issue of concern. Formosa is developing a work plan for this activity.