RALEIGH -- North Carolina soon will resume issuing air-quality permits for asphalt plants, with a stronger review process that could deny some permit applications and require tougher controls for large plants located on small sites in mountainous areas, state environmental officials said today.
The N.C. Division of Air Quality (DAQ) is lifting its 8-month moratorium on permits for new or expanded asphalt plants based on a study which found that asphalt plant emissions generally should not pose health hazards for people living nearby, DAQ Director Alan Klimek told a meeting of the General Assembly’s Environmental Review Commission.
The division will review new permits for asphalt plants on a case-by-case basis using computer models, Klimek said. The agency may deny permits or require additional controls if modeling shows emissions could exceed the state’s health-based standards for toxic air pollutants. Such controls, which are most likely for large plants located on small sites surrounded by mountains, could include taller stacks, enclosures around truck loading areas and air-quality monitoring devices.
“We have developed a workable process for permitting asphalt plants, while ensuring the protection of public health,” Klimek said. “With this process, the public can have both clean air to breathe and safe roads to drive on.”
The Division of Air Quality has had a moratorium on new permits for asphalt plants since last July, when it denied a permit for a proposed Maymead Materials plant near Boone. The division denied that permit based on concerns about the plant’s potential “fugitive emissions,” or fumes that escape from asphalt storage and truck-loading areas.
At the time, the division planned to continue the moratorium until the U.S. Environmental Protection Agency completed a national study of fugitive emissions from asphalt plants. The EPA initially planned to complete its study in the fall of 1997, but it now is not expected until at least September 1998. As a result, the DAQ conducted its own study of fugitive emissions because of the need to start considering permits again.
The DAQ study looked at 17 compounds, but focused on benzene because it is the air pollutant most likely to exceed state standards and pose hazards to public health. The study modeled the dispersion of benzene downwind from asphalt plants, showing the relative levels coming from stacks, loading areas, storage silos, and total emissions. The division ran separate models for plants located in flat and hilly terrain, with all the tests assuming worst-case weather conditions.
“In flat areas, typically we wouldn’t have a problem,” Klimek told the ERC. “In hilly areas, sometimes we could have a problem.”
The division’s study found that more than 99 percent of a typical asphalt plant’s benzene emissions come from its stacks, which have been considered under existing regulations. But fugitive emissions, although accounting for only a fraction of the total air pollution, could cause benzene levels to exceed state air quality standards -- particularly on nearby mountains that could intercept plumes drifting downwind from a plant.
In cases where needed, the controls proposed by the division would contain fugitive emissions from loading areas and vent those fumes out the stack so they could diffuse more widely into the air. Installing enclosures around loading areas would cost about $200,000 per plant, according the DAQ estimates, and monitoring benzene levels around a plant could cost about $100,000 a year.
Currently, the division has about five permit applications on hold because of the moratorium on new asphalt plants. The division plans to review each application separately, running computer models showing potential emissions of 17 toxic air pollutants.
“We will look at each one on a case-by-case basis,” Klimek told the ERC. “For controversial cases, we will hold public hearings.”
Any permits issued by the state will include a “re-open” clause, allowing the state to re-evaluate the permit if the EPA study shows other potential problems from fugitive emissions, Klimek said.
For more information, contact: Tom Mather at (919) 715-7408
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