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Home My WebLink AboutPresentation - RoxboroCOAL 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 historic 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 low, intermediate, or high. • 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 December 2015 and are posted on the departments website, local library, and health department. Department of Environmental Quality 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 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. Any hazards to public health, safety, or welfare. 2. Structural condition and hazard potential. 3. Consideration of surface 4. Consideration of groundwater. 5. The location and nature of all receptors. 6. All factors influencing the movement of contaminants. 7. Consideration of coal combustion residuals in the impoundment. 8. Position in 100 -year flood plain 9. Any other factor the department deems relevant to the establishment of risk. COAL COMB USTION RESID UAL IMPO UNDMENT RISK CLASSIFICATIONS The department 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 of Environmental Quality MAYO STEAM ELECTRIC PLANT RISK CLASSIFICATION Department of Environmental Quality MAYO STEAM ELECTRIC PLANT RISK CLASSIFICATION Overall Risk Classification DEQ has proposed the risk classification for the Ash Pond as low. Groundwater Key Factor: Based on the information received to date, there appears to be no downgradient receptors located 1,500 feet downgradient of the impoundment compliance boundary Department of Environmental Quality MAYO STEAM ELECTRIC PLANT RISK CLASSIFICATION Surface Water Key Factor: The impoundment is not located within the 100 -year floodplain. Department of Environmental Quality • Ash Pond. Low risk. The footprint of the CCR impoundment is sited in Crutchfield Branch, a natural drainage way, and it is not located within a 100 -year floodplain. • This figure depicts landscape positions in regards to the 100 - year flood level and river valley floodplain for the Ash Pond at Mayo Steam Electric Plant. MAYO STEAM ELECTRIC PLANT RISK CLASSIFICATION Dam Safety Key Factor: The impoundment received a high risk ranking before any repairs are made, intermediate risk rating after repairs are made, and a low risk rating once repairs are made and the impoundments have been dewatered. • Ash Pond (PERSO-035). High risk before repairs are made. Low risk after repairs are made. (5 repair plans have been approved by DEQ and 2 repair plans have been completed by Duke) Department of Environmental Quality R OXB OR O STEAM ELECTRIC PLANT RISK CLASSIFICATION Department of Environmental Quality ROXBORO STEAM ELECTRIC PLANT RISK CLASSIFICATION Overall Risk Classification DEQ has proposed the risk classification for the East Ash Pond as Low -to - Intermediate. Groundwater Key Factor: Based on the information received to date, there appears to be no downgradient receptors located 1,500 feet downgradient of the impoundment compliance boundary. The following data gaps related to groundwater uncertainty include: • Additional areas adjacent to the current impoundment may contain CCR and would therefore require additional assessment • Incomplete capture zone modeling • Incomplete geochemical modeling • Incomplete background concentration determination (Data gaps are currently being addressed by Duke Energy and their findings will be presented to the DEQ in supplemental reports.) Department of Environmental Quality ROXBORO STEAM ELECTRIC PLANT RISK CLASSIFICATION DEQ has proposed the risk classification for the Unnamed Eastern Extension Impoundment as Intermediate. • This impoundment was just recently identified by Duke Energy and assessment is currently underway • The location of the impoundment is in close proximity to potential receptors (Data gaps are currently being addressed by Duke Energy and their findings will be presented to the DEQ in supplemental reports.) ROXBORO STEAM ELECTRIC PLANT RISK CLASSIFICATION Surface Water Key Factor: 100 -year floodplain. The impoundment is not located within the • East Ash Pond. Low risk. The CCR impoundment is not located within a 100 year floodplain. • West Ash Pond. Low risk. The footprint of the CCR impoundment a natural drainage way. • Unnamed Eastern Extension Impoundment. Low risk. The CCR impoundment is sited in a natural drainage way, it is sited along a reservoir and it is not located within a 100 year floodplain. *The NC floodplain map depicts a 100 -year flood elevations within the west CCR impoundment. The west CCR impoundment and Hyco Lake flood elevations are predicted to be 462 and 413 feet above sea level, respectively. However, this ash basin is contained by a stream valley embankment (dam) with a discharge canal that conveys wastewater from the ash basin to Hyco Lake. Department of Environmental Quality ROXBORO STEAM ELECTRIC PLANT RISK CLASSIFICATION Dam Safety Key Factor: The impoundment received a low -to -high risk ranking before any repairs are made, low -to -intermediate risk rating after repairs are made, and a low risk rating once repairs are made and the impoundments have been dewatered. • EastAsh Pond (PERSO-033) - Low risk. (2 repair plans have been approved and 1 repair plan is under review by DEQ) • West Ash Pond (PERSO-038 & PERSO-039) - High risk before repairs are made. Intermediate risk after repairs are made. Low risk after repairs are made and the impoundments have been dewatered. (3 repair plans have been approved and 2 repair plans are under review by DEQ) • Unnamed Eastern Extension Impoundment - N/A. does not have a dam and was therefore not given dam safety. Department of Environmental Quality This impoundment a rank with respect to MAYO & ROXBORO STEAM ELECTRIC PLANT 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 mayocomments@ncdenr.gov • Postal mail to: N.C. Division of Waste Management, Solid Waste Section, N.C. Department of Environmental Quality, Attn: Ed Mussler, 1646 Mail Service Center, Raleigh, NC 27699-1611 Department of Environmental Quality