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HomeMy WebLinkAboutMulti ID#'s_Accelerated Remediation Summaries_20160217,DUKE �. , ENERGY® Harry K. Sideris Senior Vice -President Environmental, Health & Safety 526 South Church Street: Mail Code EC3XP Charlotte, North Carolina 28202 704382-4303 February 17, 2016 Mr. Donald R. van der Vaart, Secretary North Carolina Department of Environmental Quality 1601 Mail Service Center Raleigh, North Carolina 27699-1601 Subject: Accelerated Remediation Summaries Dear Mr. van der Vaart: Attached are summary documents describing accelerated remediation activities at the following Duke Energy facilities: Asheville Steam Electric Plant Belews Creek Steam Station H.F. Lee Electric Plant L.V. Sutton electric Plant If you have comments and/or questions, please direct them to me at 704-382-4303. Sincerely, Harry K. Sideris Senior Vice -President Environmental, Health & Safety L. V. Sutton Electric Plant Proposed Accelerated Remediation for Offsite Groundwater Impacts 1.0 Background A Notice of Regulatory Requirement (NORR) was issued by NCDENR on June 9, 2015 requiring Duke Energy to take action to control and prevent further migration of coal ash contaminants along the east side of the L.V. Sutton Plant (Sutton Plant). A Groundwater Mitigation and Monitoring Plan was submitted to NCDENR on July 9, 2015 outlining the proposed plan to address the NORR. A Settlement Agreement (Agreement) dated September 29, 2015 between NCDEQ (formerly known as NCDENR) and Duke Energy requires Duke Energy to implement accelerated remediation along the eastern Sutton Plant property boundary where data indicates ash basin related constituent concentrations above 2L Standards have migrated off-site. As part of the Agreement, the NORR dated June 9, 2015 was withdrawn. The Agreement requires Duke Energy to implement accelerated remediation at the Sutton Plant on the following terms and conditions specifically related to the off-site groundwater impacts: • Extraction wells will be used to pump groundwater to arrest the off-site extent of the migration. • Groundwater will be pumped and treated as needed to meet regulatory standards and the treated groundwater will be routed to the ash basin or the discharge canal. • The extraction and treatment system will be installed as soon as practicable following receipt of all permits and approvals from NCDEQ and is in addition to other Coal Ash Management Act (CAMA) obligations. • Extraction wells shall remain operational until it is demonstrated, subject to NCDEQ's written concurrence that off-site groundwater impacts have been remediated to 2L Standards and there is no reasonable potential for future off-site migration. 2.0 Scope The following steps are recommended: • Conduct an aquifer/pump test to evaluate site-specific physical properties of the aquifer and obtain data for the extraction well system design. (Status — The 3 -day pump test is scheduled to be completed in March 2016 pending receipt of permits.) • Provide extraction and treatment system design to NCDEQ for review and approval. • Due to NPDES Permit limits the construction of an ash basin dewatering treatment system is required. (Status — Construction of the ash basin dewatering treatment system is currently underway and expected to be completed later in 2016.) • Potentially 1.3 MGD of groundwater could be generated from the proposed extraction system. Treatment through the dewatering system is the most practical approach to handling extracted groundwater. In addition to the groundwater modeling required by CAMA, additional groundwater modeling simulations using supplemental extraction wells may be performed to improve recovery of impacted groundwater near the ash basins. These supplemental extraction wells would be located between the ash basin and the east property boundary. 3.0 Challenges Challenges include obtaining permits or modifications to existing permits and working in coordination with other ongoing Site construction/remediation activities. February 17, 2016 1 of 3 L. V. Sutton Electric Plant Proposed Accelerated Remediation for Offsite Groundwater Impacts Permits required • Schedule is dependent on ash basin dewatering treatment system • Approval of action from NCDEQ DWR • NCDEQ recovery well permits • Erosion & Sediment Control permit • Modification to the State Stormwater Permit (applies to coastal counties) • Potential New Hanover County building/electrical permits (remediation compound) Construction/Remediation System Challenges • Working around landfill construction activities • Working around ash loading activities • Working around construction of dredging water treatment system • Power to pumping system area • Long term discharge location (Discharge canal, cooling pond or Cape Fear River) 4.0 Figure Figure 1: Sutton Plant February 17, 2016 2 of 3 L. V. Sutton Electric Plant Proposed Accelerated Remediation for Offsite Groundwater Impacts 5.0 Conceptual Schedule Task Description Estimated Length of Time Estimated Completion Date Aquifer Pump Test System Installation 1 week 3/14/16 Aquifer Test and Reporting 4 weeks 4/15/2016 Extraction System Engineering Design 6 weeks 5/27/2016 Extraction System NCDEQ Approval 6 weeks 7/8/2016 Extraction System Bidding/Contractor Selection 4 weeks 8/5/2016 Extraction System Installation 16 weeks 11/25/2016 Completion of Ash Basin Dewatering Treatment System (currently underway) 48 weeks 12/4/2016 Extraction System Start Up and Testing 4 weeks 12/23/2016 Extraction System Certification Report (Final Submittal to NCDEQ) 8 weeks 2/17/2017 February 17, 2016 3 of 3 Asheville Steam Electric Plant Proposed Accelerated Remediation for Offsite Groundwater Impacts 1.0 Background On September 29, 2015, Duke Energy entered into a Settlement Agreement with North Carolina Division of Environmental Quality (NCDEQ) to resolve issues relating to alleged exceedances of state groundwater standards associated with coal ash facilities operated by Duke Energy (Duke) and its predecessors. This agreement requires Duke to implement accelerated remediation at the Asheville Steam Electric Plant for offsite groundwater impacts. Groundwater sampling performed for the Asheville Steam Electric Plant Comprehensive Site Assessment found exceedances of 2L Standards or IMACs for boron, cadmium, chloride, cobalt, iron, manganese, selenium, sulfate, thallium, total dissolved solids (TDS), and vanadium in monitoring wells located west of Interstate 26. The monitoring wells of note are located on Duke Energy property and the receptor survey (included in the CSA) indicates there are no public or private water supply wells located in the area with groundwater impacts mentioned above. Five private water supply wells are located adjacent to Duke Energy properly along Bear Leah Trail. Sampling of these wells has been conducted numerous times since 2013. Results indicate iron and manganese are present above the 2L Standard. Additional assessment activities including groundwater sampling, boron isotope analysis, additional monitoring well installation, and down hole camera work has been conducted to further evaluate the area near Bear Leah Trail. 2.0 Scope The following steps are in process. • Installation of a water line along Bear Leah Trail. This activity was completed during the week of February 1, 2016. Currently all residences along Bear Leah Trail are serviced by a public water supply. • Conduct borehole geophysics to further refine the Site Conceptual Model (SCM). Borehole geophysics is being conducted during the week of February 16, 2016. • Permanently abandon private water supply wells along Bear Leah Trail to eliminate potential receptors. This work is currently scheduled for the week of February 22, 2016. • Discontinue use and remove the FGD wastewater treatment wetlands. (Status - Removal of the wetlands is nearing completion. All flow to the wetlands has been diverted to the municipal sewer with complete removal of the wetlands anticipated early in 2016.) • Dewater the settling pond resulting in lower hydraulic heads within the 1964 basin. The Mountain Energy Act of 2015 requires closure of the coal combustion residual surface impoundments no later than August 1, 2022. Predictive numerical groundwater modeling indicates modest improvement to groundwater quality in response to ash removal. (Status - A November 13, 2015 update to the Coal Ash Excavation Plan indicates excavation of the 1964 basin is currently planned to begin in 2020 (hftps://www.duke- energy.com/pdfs/asheville-excavation-plan.pd ). February 17, 2016 1 of 2 Asheville Steam Electric Plant Proposed Accelerated Remediation for Offsite Groundwater Impacts 3.0 Challenges • Ongoing projects — limited space 4.0 Figure Figure 1: Asheville Plant Ash Basins and Bear Leah Trail February 17, 2016 2 of 2 H.F. Lee Energy Complex Proposed Accelerated Remediation for Offsite Groundwater Impacts 1.0 Background On September 29, 2015, Duke Energy (Duke) entered into a Settlement Agreement with North Carolina Division of Environmental Quality (NCDEQ) to resolve alleged exceedances of state groundwater standards associated with coal ash facilities operated by Duke and its predecessors. This agreement requires Duke to implement accelerated remediation at the H.F. Lee Energy Complex for offsite groundwater impacts. Results of the Comprehensive Site Assessment (CSA) indicated that exceedances of 2L Standards, primarily for arsenic and boron, were present in monitoring wells north and east of the H. F. Lee active ash basin. The monitoring wells are located near the property lines in these areas. The CSA also included sampling of groundwater seep locations along the perimeter ditch north and east of the active ash basin. Samples collected at these locations showed exceedances of 2L Standards or IMACs for arsenic, boron, iron, manganese, thallium and vanadium, and elevated concentrations of total dissolved solids. The primary groundwater flow direction from the active ash basin is to the south, towards the Neuse River. Historic use and standing water within the ash basin produced a radial distribution of arsenic and boron in groundwater in the immediate vicinity of the ash basin to the east and to a lesser extent to the north. The receptor survey (included in the CSA) indicates: 1) there are no private water supply wells located to the east of the active ash basin, and 2) there are no private water supply wells located between the ash basins and the river, 3) public water lines service the area. Additional groundwater assessment to refine the assessment around the active ash basin is planned. 2.0 Scope To address the requirement for accelerated remediation in the recent NCDEQ and Duke Energy agreement, the following steps are recommended. East of active basin • Acquire private property east of the active basin. • Develop conceptual design and modeling for groundwater extraction via recovery wells or a collection trench along the east side of the active basin • Develop 401 permit to access wetlands for additional assessment and potential corrective action recovery wells or trench • Model effects of potential groundwater extraction system on the wetlands hydrology • Install french drain system to minimize the connection between the active basin and adjacent surface water drainages. (Status — The installation of a french drain system is being reviewed with EPA and DEQ.) • Conduct groundwater monitoring to assess beneficial impact of french drain system on groundwater quality. • Following acquisition of property, conduct wetlands survey and install additional data gap wells to further define the extent of boron and other constituents. North of active basin • Acquire private property north of the active basin. • Discontinue discharge to basin to prevent mounding in the area February 17, 2016 1 of 2 H.F. Lee Energy Complex Proposed Accelerated Remediation for Offsite Groundwater Impacts • The dominant groundwater flow direction is to the south. The groundwater data on the north side of the basin suggesting an area of arsenic and boron impact is limited to one on-site monitoring well and a limited recent data set. (Status — Initial review of third and fourth round sampling data indicates a reduction in boron and arsenic concentrations in MW -1 on the north side of the active basin.) • Following acquisition of property, install additional assessment wells to further define the extent of boron and other constituents. • Analysis of groundwater monitoring will determine the need for additional remediation. 3.0 Challenges Additional Permits/Challenges Should Active Remediation Be Necessary • Implementing groundwater withdrawal east of the active basin could degrade wetlands • Long lead time required to develop treatment system and discharge location • Substantial wetlands permitting • Approval of action from NCDEQ DWR • NCDEQ recovery well permits • Erosion & Sediment Control permit • Modification to the NPDES permit • Potential Wayne County building permit 4.0 Figure Figure 1 — H.F. Lee Active Ash Basin February 17, 2016 2 of 2 Belews Creek Steam Station Proposed Accelerated Remediation for Offsite Groundwater Impacts 1.0 Background The Winston Salem (WS) Regional office recently expressed concern in regards to groundwater near the Belews Creek Steam Station, west and southwest of the Pine Hall Landfilll (south/southwest of the ash basin). The WS regional staff requested additional bedrock wells to better define bedrock conductivity. The WS regional staff and Duke agreed to install four additional bedrock wells on the western side of the ash basin and west/southwest of the Pine Hall Landfill in addition to one shallow and deep well southwest of the Pine Hall Landfill (see Figure 1). The shallow and deep well pair will be utilized to refine groundwater flow direction in the area of installation. The six wells are in addition to the previously defined data gap wells. The WS regional staff requested additional reporting for the onsite lined landfill facilities as well as construction logs to be provided in the Corrective Action Plan for wells determined to be background (onsite and as apart of the Duke 2-10 program). Duke explained that well construction logs might not exist for 2-10 wells. 2.0 Scope The following steps are recommended: • Compare Round 2 analyses of groundwater monitoring with Round 1. • Accelerate installation, sampling, and analyses of additional assessment wells planned for this facility. [Status - E&SC permit received on Feb 11, 2016 (dated February 4, 2016). Drilling is anticipated to begin February 23, 2016] A permit modification will be required for the additional wells requested by the WS regional office. • Research will be completed to determine if construction documentation is available for wells in the Duke 2-10 background program • Background wells for Belews Creek FGD and Craig Rd Landfills will be reviewed to determine if the background wells at these landfills are in the same geologic formation as the ash basin. A summary of review with boring and construction logs will be prepared for submittal to the WS regional office. 3.0 Challenges • Erosion & Sediment Control permit • Fluctuation of water levels in the ash basin may affect groundwater flow direction February 17, 2016 1 of 3 p`mW �{iryl�l p,L � � `A4 �RF50 f� 404E sV'uf �-' � wMV11W3 ��'R.4j V / 'RB HAIL XOA3 ,Z ASH U NOPLL VFNMIFNO. ` Blatta ': TJU uk r< oa i as ca ! MUCTJRAc "41, : u�,rn wN Q' Qa4iEi / SwA.Lt� Belews Creek Steam Station Proposed Accelerated Remediation for Offsite Groundwater Impacts 5.0 Conceptual Schedule Task Description Estimated Length of Time Estimated Completion Date Real Estate pursue property purchase Ongoing Data gap and additional well engineering design Complete Data gap and additional well NCDEQ permit review and receipt Data Gap Wells Additional Wells Complete Ongoing Data gap and additional well installation 4 weeks 3/25/2016 Data gap and additional well sampling 1 week 4/1/2016 Analysis of data gap and additional wells 3 weeks 4/22/2016 Research availability of 2-10 well construction records ongoing Review of onsite lined landfill facilities and report compilation (begin February 22) 4 weeks 3/25/2016 Update Regional Office on 2-10 construction records and onsite landfill research 3/15/2016 Meet with Regional Office to review data findings associated with 2-10 and onsite landfill research and additional well sampling results 5/6,2016 February 17, 2016 3 of 3