Regulators authorize repairs to dam structure at Duke Energy coal ash impoundment

From press release:

RALEIGH — State environmental regulators have given Duke Energy permission to lower the level of a coal ash storage pond to make repairs to a dam structure at the Marshall Steam Station in Catawba County.

The N.C. Department of Environment and Natural Resources on Thursday granted the utility authorization to lower the level of the ash impoundment only after state and Environmental Protection Agency officials consulted on Duke Energy’s request. The utility requested it be allowed to lower the level of the coal ash impoundment to make necessary repairs to a corrugated metal pipe that is part of the decant system that filters wastewater in the ash pond. The Division of Energy, Mineral and Land Resources has approved repairs to the pipe.

The EPA and state regulators determined the repairs are authorized under a provision of the utility’s National Pollutant Discharge Elimination System permit that allows lowering pond levels for essential maintenance to a dam as long as the utility does not exceed permitted wastewater discharge limits during maintenance.

DENR sent a letter Thursday to Duke Energy giving permission to proceed with the project but directed the utility to collect and test wastewater discharges during the maintenance project to ensure that the permitted effluent discharges are not exceeded. Duke Energy is allowed to discharge wastewater from the coal ash impoundment at Marshall Steam Station to Lake Norman, which flows to the Catawba River.

“Though notification of activities or approval is not explicitly required by regulation, DWR (Division of Water Resources) may review other submitted dam repair projects to convey to Duke Energy a better understanding of our interpretation of essential maintenance activities,” Jeff Poupart, the state water quality permitting section chief, stated in the letter sent to Duke Energy Thursday.

Copies of the letters DENR sent to Duke Energy approving the lowering of the storage pond and repairs to the pipe can be found on DENR’s coal ash website under the heading “Correspondence with Duke Energy” at: http://portal.ncdenr.org/web/guest/dan-river-documents.

The Marshall Steam Station is one of many Duke Energy coal ash facilities that will require state approvals to remove coal ash water to allow for repairs to dam structures or prepare for ash pond closure. Plans submitted by Duke Energy for those activities are being reviewed by the state divisions of Water Resources and Energy, Mineral and Land Resources.