US Nitrogen Issued Five Permits

By Walter F. Roche Jr.

Acting on the eve of a long holiday weekend Tennessee regulators have issued five key permits to a Greene County chemical firm assuring its continued operation for two more years.
The permits were issued late Friday to US Nitrogen LLC by the Tennessee Department of Environment and Conservation. The agency largely refuted or ignored more than a dozen suggested changes to the permits submitted by an environmental consultant and the Sierra Club.
Calling one of the changes neither necessary or required the state agency also issued a 23-page summary of the proposed changes and the agency response.
TDEC did agree to a handful of small changes including requiring US Nitrogen to submit photographs demonstrating that a boiler at the Midway plant actually had been disconnected.
The permits were the subject of sparsely attended June public hearings at which the Sierra Club, Park Overall and her consultant, D. Howard Gebhart, testified. Gebhart also submitted written comments.
The permits cover US Nitrogen's plant, an ammonia nitrate plant, cooling towers, flares and a steam generating boiler. They are categorized as conditional major permits and they replace a series of construction permits issued when the ammonium nitrate manufacturer first went into operation.
By agreeing to the limits the company avoided stricter regulations under a major source operating permit.
A key element in the new permit scheme is that US Nitrogen is now operating under its own permits and two other firms on the same site, Praxair Inc and Yara North America, are operating under their own separate permits. The initial construction permits covered all three operations.
The Sierra Club had argued against the permit separation, but TDEC, citing the fact that the three firms are under separate control, rejected that argument.
Under the permits US Nitrogen agrees to operate within certain set limits on annual emissions.
For instance nitrous oxide emissions cannot exceed 3.4 tons per year and carbon monoxide emissions are capped at 2.54 tons per year. The annual emissions limit for volatile organic compounds is set at 1 ton.
Gebhart, who submitted written comments, argued that the proposed permits did not include adequate requirements to ensure the company was complying with the agreed emission limits. He also argued for monitoring of air quality in the community.
TDEC did agree to include a requirement that US Nitrogen certify on an annual basis that it was operating within the prescribed limits.
The agency also added a provision "to make it clear" that emissions of nitrous oxide and carbon monoxide are less than five tons per year each.
TDEC acknowledged that under the new permit US Nitrogen will be allowed to increase its natural gas use in the steam boiler by 18 percent. The company recently disclosed that it had exceeded the current limit in four successive months.
TDEC said that under the new limits the annual limit on particulate matters is 16.35 tons per year, .56 tons for sulfur dioxide, 90.82 tons of nitrous oxide and 69.2 tons of carbon monoxide.
"Thus even with the slight increase in allowable emissions, the facility is still a non-major source for all pollutants," the TDEC document states.
Though Gebhart had argued that further modeling was required before allowing any increases, TDEC said modeling done before the initial permit, which also included the Praxair and Yara operations, was more than adequate.
TDEC said it did add a requirement that US Nitrogen conduct "performance testing" to assure compliance with carbon monoxide limits.
As for ambient air monitoring, TDEC asserted it was "neither required or necesary."
Also rejected was the proposal that additional monitoring be required during the start-ups of the nitric acid plant, which have been the source of community complaints.
In rejecting the request for community monitoring, TDEC cited US Nitrogen's recent disclosure of a "process change that significantly improved the startup opacity levels."