PCS Phosphate: Air quality permit sees light of day, stinks

We’re continuing to dig through the permits and background pertaining to the recent revelation the PCS Phosphate has nearly completed the permitting process for a new sulfur processing plant at the Morehead City Port. The most apparent environmental and health impact of sulfur processing is noxious chemical emission and a pervasive rotten egg smell from hydrogen sulfide. According to PCS Phosphate’s Environmental Assessment:

“Based on assessments of the preliminary design of the project, there will be no adverse air quality impacts associated with the project.”

The company is still required by the state to apply for a minor new source permit, so the plans must indicate the plant will be emitting something. As local residents, we have a right to know what the plant will emit, not just the company’s bottom line.

The Department of Air Quality issued the permit to PCS Phosphate on June 2, though their website still lists it (#1600145.11B) as an active application. Neither the Environmental Assessement nor the DAQ website have information about the quantity and type of emissions, nor has either process included public comment. Two complaints here: we should have had a chance to comment on the permit before it was released and we should now have easy access to the permit documentation.

The good folks over at the NC Coastal Federation fortunately located the permit documentation for me: both the permit and the state’s review. First, here’s the basics of what they’re emitting and how they propose to take care of those emissions:

  • hydrogen sulfide removed by 2 caustic scrubbers in the proposed smokestacks
  • particulate matter to be kept below 0.34 lbs per million Btu used
  • sulfur dioxide should not exceed 2.3 lbs per million Btu used, controlled by only using fuel sources (oil and natural gas) with less than 0.5% sulfur by weight
  • odor beyond the facility’s borders are prohibited

I believe the particulate matter and sulfur dioxide prescriptions because these are common industry problems that have developed relatively easy solutions. However, I’m more curious about the hydrogen sulfide.

The permit goes into more detail for hydrogen sulfide, which is perhaps the most direct threat to human health. The permit states that formed solid sulfur that is melted will contain less than 50 ppm hydrogen sulfide and that molten sulfur will flow through the bottom of the tank to minimize release. Two scrubbers will be placed on gas outflows from both the melter and storage facilities that are expected to capture 98% of the hydrogen sulfide. That leaves 2%, or 4.536kg per day, to be emitted as air pollution, which is about what they received the permit for (13 lbs).

The permit also includes an ‘operating scenario 2’ in which molten sulfur will be shipped in from elsewhere and stored at the Port. In this case, the stored sulfur is permitted to emit 216 lbs (98 kg) per day.

Wondering what the toxicological profile of hydrogen sulfide is? The Occupational Safety and Health Administration limits exposure to 20 ppm in ambient air and 50 ppm in an acute exposure. These are at or below the limits in what is permitted for the formed solid sulfur. Not all of the hydrogen sulfide will be released at once, but those limits are likely within reach of full production capacity. Hydrogen sulfide can cause respiratory, brain and nerve paralysis. And how does this amount affect local ecosystem service provision and fit in with community goals for the area? Let’s re-think the permitting.

July 24, 2011 • 8:46 pm