TDEC Says No Damage from US Nitrogen Incident

By Walter F. Roche Jr.

Tennessee environmental officials have concluded that there was no damage from the April 19 release of nitric acid vapor from the US Nitrogen's Midway plant and any harm to residents was unlikely.
In a nine-page report, the Tennessee Department of Environment and Conservation also said that under state and federal regulations US Nitrogen was not even required to report the incident because the amount of nitric acid released was well below the threshold triggering a reporting requirement.
The agency did say that it was referring one complaint from a local resident to the state Health Department.
In a letter to US Nitrogen accompanying the report, TDEC division director Michelle W. Owenby, said the agency was closing its investigation.
According to the report, about 424 pounds of nitric acid was released over a four minute period in the April incident caused by the rupture of a heat exchanger. However, it states the level that triggers a reporting requirement is 15,000 pounds.
"In the case of the April 19, 2017 incident, the amount released is below the reportable thresholds and USN reported the release incident even though it fell below the reporting levels as identified," the report states.
In addition the reporting requirement only applies to releases with a concentration of 80 per cent or more, but the nitric acid in use at US Nitrogen had a concentration of only 59 per cent, TDEC found.
"For reasons noted above, the division concludes that section 112(r) of the Clean Air Act is not applicable to the event on April 19, that involved nitric acid of 59 per cent concentration," the report continues.
Citing the fact that much of the land around the US Nitrogen plant is owned by the company or the Industrial Development Authority, TDEC concluded that "no serious environmental or health impacts likely occurred."
The report states that the closest school, West Greene High School is 1.9 miles away and the Mosheim Elementary School is 2.7 miles east of the plant. The closest business is about a quarter mile away.
The population density is very low in the area and the closest residences are nearly a half mile away, the report states.  In addition the release occurred at 6 p.m. when "local schools would not be in session and most local businesses would have already closed for the day."
TDEC did note that a "vehicle reconnaissance" of the area showed evidence of old homes or residences located on the properties owned by US Nitrogen and the IDB.
As for the weather, TDEC said that the presence of rain showers at the time of the release "likely helped to mitigate the transport of any nitric acid emissions associated with the event."
TDEC did say that it received one complaint of "alleged health-related impacts associated with the event." The agency also received one anonymous call complaining of health related effects, but that caller chose not to file a formal complaint.
The one formal complaint is being referred to the state Health Department.
"Finally, the division does not believe any environmental damage occurred as a result of the April 19 incident," the report concludes.