Press release from N.C. Department of Environment and Natural Resources about a “discharge” from the Cliffside Steam Station:
RALEIGH – Staff members from the Department of Environment and Natural Resources responded Thursday afternoon to notification of a discharge from an emergency yard drainage overflow pipe at Duke Energy’s Cliffside Steam Station in Rutherford County.
On Thursday afternoon, during a routine inspection of the plant site, Duke Energy officials informed the department that they discovered the discharge of approximately 0.8 gallons per minute coming from the permitted outfall of an emergency pond. Discharge from this pond is expected only during extreme storm events. Duke Energy found that a corrugated steel outfall pipe was perforated due to corrosion thereby allowing groundwater to infiltrate the pipe. Water infiltrating the pipe was reported to have discharged to the ground at a riprap area and never reached the Broad River, the waterbody closest to the plant.
“Fortunately, we observe no environmental impacts from this discharge,” said Tom Reeder, director of the N.C. Division of Water Resources. “However, we need to emphasize increased attention to all aspects of the infrastructure at Duke Energy’s facilities across the state.”
Attempts to repair the pipe on Thursday were unsuccessful. Friday morning, Duke Energy personnel began containing and collecting the discharging water into collection tanks. The company plans to pump and haul the collected water from the collection tanks to a treatment pond on site twice a day until a permanent remedy has been implemented.
In compliance with permit conditions, Duke Energy personnel on Thursday collected flow data and took samples of discharge water to be tested for total suspended solids, oil, grease and pH. Friday morning, Duke Energy staff also gathered discharge water samples to be tested for total metals, total dissolved solids, nutrients, total suspended solids, turbidity and sulfates.
The basin where the pipe is located is designed to hold co-mingled stormwater and wastewater overflow from an adjacent basin during extreme storm events. The last time the basin was used for emergency storage was in 2005 when a heavy storm brought 9 inches of rain to the area.
In this case, corroded areas of the pipe allowed groundwater to enter and move up through the pipe to the discharge point, where water was discharged and infiltrated the soil.
Representatives from DENR’s Dam Safety Program plan to be on site early next week for a scheduled dam safety inspection and will also have an opportunity to examine the structure.