By Walter F. Roche Jr.
For the second year in a row officials of US Nitrogen are reporting that storm water running off from its 500 acre Midway site has magnesium levels far in excess of national cutoff limitations.
In a letter and report to the Tennessee Department of Environment and Conservation, US Nitrogen Plant Manager Andrew Velo said the excessive levels were found at the same two monitoring sites as last year, but at slightly lower levels.
According to the report 5.54 milligrams per liter were recorded at one site while 10.6 milligrams per liter were recorded at the other. A year ago the levels at the same two sites were 6.44 milligrams per liter and 12.3 milligrams per liter respectively.
The national cutoff is .0636 milligrams per liter.
"We suspect the source of the magnesium detected in the storm water samples is from background concentrations, potential fertilizer application and from water flowing across rock," Velo wrote in the Aug. 26 letter to TDEC.
The data was included in an annual storm water monitoring report US Nitrogen has to file as a condition of its TDEC permits.
Velo's letter states that while the plant had begun operating, it does not use magnesium in any of its production operations.
The plant has shutdown temporarily following two incidents in which air pollution limits were apparently exceeded. The two incidents are under investigation by state and federal regulators.
As they did a year ago, US Nitrogen officials noted that excess magnesium levels have been detected in the Nolichucky River.
Velo stated that the company has made efforts to reduce the use of fertilizers as that may be a source of magnesium.