Mercury Minimization: Public Outreach in Tabor City
As a result of a state-wide Total Maximum Daily Load (TMDL) approved by the US EPA on October 12, 2012, the Town’s new NPDES permit for its wastewater treatment plant included the requirement for a mercury minimization plan. This plan includes targeting potential sources of mercury from commercial/industrial customers as well as public education about household sources of mercury.
What is a TMDL? Simply, a TMDL is a calculated maximum limit of a pollutant that can enter a body of water and still allow it to meet water quality standards. A TMDL strategy targets specific reductions of that pollutant that are necessary and identifies ways to reduce the amount of that pollutant that enters a water body.
What is an NPDES permit? A National Pollutant Discharge Elimination System (NPDES) permit is required by the Clean Water Act and controls the amounts of pollutants in treated wastewater that can be discharged in a body of water. The limits in these permits are set to protect water quality, aquatic life and human health.
Where does mercury in water come from? Based on data from the US EPA and the NC Department of Environmental Quality, the majority of the mercury found in the waters of NC are from air sources. Mercury is a naturally-occurring metal; however, human activities have increased its presence. Wastewater discharges may contain some mercury but are very minor compared to the amounts of mercury found in the air.
Why was a Mercury TMDL put in place in North Carolina? In very simple terms, the inorganic mercury deposited from air sources into the water and soils is converted by microorganisms to a more harmful form of mercury, methylmercury, which then can be taken up by aquatic life. It then builds up in the tissue of aquatic organisms, such as fish. Fish tissue testing across the state had been showing elevated levels of mercury resulting in a fish consumption advisory. This Mercury TMDL is a regulatory strategy to reduce the amount mercury entering the environment and thus being able to accumulate in aquatic and terrestrial plants and animals. Additional information on the NC Mercury TMDL can be found here: https://deq.nc.gov/about/divisions/water-resources/planning/modeling-assessment/special-studies/mercury-tmdl
What can you do to reduce the amount of mercury released into the environment? The simplest way is to become an educated consumer. Proper disposal and handling of household items that may contain mercury can help immensely. In fact, did you know that mercury can be found in everything from appliances, batteries and light bulbs to pharmaceuticals, jewelry and skin cream? Find out more about household sources of mercury and what you can do to help reduce mercury in the environment here: https://www.epa.gov/mercury
What is Tabor City doing at its wastewater treatment plant to ensure that mercury is not being released through its wastewater discharge? A Mercury Minimization Plan (MMP) has been prepared and the Town continues to monitor for mercury at various points within the treatment train at the plant, including the wastewater coming into the plant and the treated water leaving the plant. In addition, the Town has surveyed all potential commercial and industrial customers to ensure that their activities are not generating/using mercury that enter the wastewater system. If new a new industry plans to locate in Tabor City, they are required to submit data that provides a representative profile of the type of wastewater, including pollutants and their levels, that would be discharged. If there is any concern about the types and levels of pollutants, these customers would be required to pre-treat their wastewater or would not be allowed to discharge into the Town’s system. Finally, the Town is monitoring its influent for mercury and can detect quickly if mercury is found. This would trigger inspections of likely sources and require immediate action by any responsible customers.