As a follow-up to our previous update, we want to provide new information about the steps we’re taking to minimize the odor near the Kings Mountain Mine pit.
We have installed 10 new air monitoring systems surrounding the pit – more than twice as many as we had before. All readings of hydrogen sulfide remain more than 10 times lower than regulatory health and safety guidelines. In addition, we have been in close contact with local, state and federal officials, and we welcome further engagement from regulatory authorities to perform additional independent air monitoring as necessary.
As a reminder, seasonal changes in temperature and wind can cause the deeper, odor-causing water in the mine pit to rise to the surface. This water contains hydrogen sulfide created from the natural decomposition of organic material, which can cause the odor. This is a natural occurrence, commonly referred to as “turning over,” that can happen in lakes and ponds in our region and throughout the world.
Until the mine pit can be fully dewatered, intermittent odors are possible, especially when persistent cold temperatures are expected to continue. Here’s some of the steps we’re taking:
- We are temporarily relocating a water intake that is being used as part of our dewatering operations to draw water from the lower levels of the mine pit where sulfide levels are higher. The water is then transferred to a water treatment facility, where sulfide is removed. As necessary, water can be returned to the mine pit to increase the amount of low-sulfide water in the top layer.
- We are considering installing buoy-like objects on the surface of the water. The objects are designed to disrupt wind-caused movement of water and further prevent the continued mixing of the upper and lower levels of the water.
- We’re studying the use of a “batch treatment.” That’s a process where a reactant would be added to the mine pit water to help neutralize the odor-causing sulfide.
As members of the Kings Mountain community, we are committed to sharing updates on our continued efforts, but if you have any questions or concerns, we encourage you to reach out to our Community Relations staff by phone (704-734-2775) or email ([email protected]).