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Home My WebLink AboutPresentation - MarshallCOAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS March 2016 Collaboration between: Division of Water Resources Division of Waste Management Division of Energy, Mineral and Land Resources Department of Environmental Quality COAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS Background: • Under the Coal Ash Management Act (CAMA) of 2014, all coal ash impoundments in North Carolina are required to be closed. • The deadlines for closure depend on the classification of each impoundment as either low, intermediate, or high. • A high or intermediate risk classification for an impoundment requires excavation. A low risk classification for an impoundment allows options for placing an engineered cap in place or excavation for closure. Excavation may be the remedial action for a low risk impoundment. Department of Environmental Quality 2 COAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS Background continued: • CAMA required the Department of Environmental Quality (DEQ) to make available to the public a summary of the initial draft proposed classifications in December 2015, and a full report in January 2016. • These draft proposed classifications are based on the information available to the Department as of January 2016 and are posted on the Department's website, local library, and health department. • The draft proposed risk classification for the Marshall Steam Station is Low to Intermediate for the Active Basin 1. • Following completion of the public meetings and the submission of comments, the Department will consider the comments and develop final proposed classifications. Department of Environmental Quality 3 COAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS After the release of the summary of the initial draft proposed classifications, CAMA requires the following process: • DEQ must make available a written declaration that is a detailed report explaining the technical and scientific background data and analyses behind the draft proposed classifications. • Publish a summary of the detailed report in the local newspapers. • Make the report available to the local health director and accessible at the local library. • A public meeting in each county with a coal ash facility. • Consider all public comments and develop final proposed classifications. Department of Environmental Quality 4 COAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS Closure Deadlines • High risk impoundments: Dec. 31, 2019 • Closure plan due by Dec.31, 2016 • Intermediate risk impoundments: Dec. 31, 2024 • Closure plan due by Dec. 31, 2017 • Low risk impoundments: Dec. 31, 2029 • Closure plan due by Dec. 31, 2018 COAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS Four of Duke's 14 facilities are designated as high-risk by the coal ash law. Under CAMA, the department is required to consider the following factors, at a minimum, in proposing classifications for the remaining 10 facilities: 1 2 3 4 5 6 9 Any hazards to public health, safety, or welfare resulting from the impoundment Structural condition and hazard potential of the impoundment Consideration of the proximity of surface waters and whether surface waters are contaminated or threatened by contamination Consideration of the extent of soil and groundwater contamination The location and nature of all receptors and significant exposure pathways All factors influencing the movement and the chemical/physical characteristics of contaminants Consideration of coal combustion residuals in the impoundment with respect to volume and position to the water table Consideration of coal combustion residuals in the impoundment with respect to the 100 -year floodplain Any other factor the Department deems relevant to the establishment of risk COAL COMBUSTION RESIDUAL IMPOUNDMENT RISK CLASSIFICATIONS The epartment incorporated all of the preceding criteria into three primary categories that were used to evaluate each impoundment: • Structural Integrity • Impact to Surface Water • Impact to Groundwater The draft classification process was iterative and occurred over a series of months. Recommendations regarding the impoundments were amended and updated as additional scientific and technical information was received, reviewed and verified. Department ofEnvironmental Quality 7 MARSHALL STEAM STATION RISK CLASSIFICATION Department of Environmental Quality MARSHALL STEAM STATION RISK CLASSIFICATION Overall Draft Risk Classification Marshall Steam Station Overall Draft Risk Classification DEQ has proposed the risk classification for the Ash Basin as Low to Intermediate. Groundwater Key Factor: • Based on the information received to date, there appears to be no downgradient receptors located within 1,500 feet downgradient of the impoundment compliance boundary Other Factors and Considerations: • There are data gaps and uncertainty concerning site conditions at the facility related to groundwater • These data gaps are currently being addressed by Duke Energy and their findings will be provided to DEQ as supplemental reports Department of Environmental Quality I MARSHALL STEAM STATION RISK CLASSIFICATION Surface Water Key Factor: 100 -year floodplain. The impoundments are not located within the Department of Environmental Quality 10 Ash Basin. LOW RISK. The CCR impoundment is sited in a natural drainage way of Holdsclaw Creek. The NC floodplain map depicts a 100 -year flood elevation within the footprint of the ash impoundment but it is contained within the 37 foot tall embankment. MARSHALL STEAM STATION RISK CLASSIFICATION Dam Safety Key Factor: The impoundment received a high risk ranking before any repairs are made, an intermediate risk ranking after the repairs are made, and a low risk ranking once repairs are made and the impoundment has been dewatered. • Ash Basin (CATAW-054). High Risk before repairs are made. Intermediate Risk after repairs are made. Low Risk once repairs are made and impoundment has been dewatered. (3 repair plans have been approved and 2 repair plans are under review by DEQ and of those 2 repair plans have been completed by Duke) Department of Environmental Quality MARSHALL STEAM STATION RISK CLASSIFICATION We will now receive public comments To view additional information please visit www.deg.nc.gov The public comment period will close on April 18, 2016 You may submit comments three ways, all weighted equally: • Here orally and/or in writing • Email to marshalIcomments@ncdenr.gov • Postal mail to: N.C. Division of Water Resources, Groundwater Protection Section, N.C. Department of Environmental Quality, Attn: Debra Watts, 1636 Mail Service Center, Raleigh, NC 27699-1611 Department of Environmental Quality 12