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Home My WebLink AboutNC0005088_CSS Assessment Work Plan_Final_20140925 Cliffside Steam Station Ash Basin Proposed Groundwater Assessment Work Plan NPDES Permit NC0005088 September 25, 2014 Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin TABLE OF CONTENTS i Table of Contents Page Table of Contents ......................................................................................................................... i Executive Summary .............................................................................................................. ES-1 1.0 Introduction ..................................................................................................................... 1 2.0 Site History ...................................................................................................................... 2 2.1 Plant Description ...................................................................................................... 2 2.2 Ash Basin Description ............................................................................................... 2 2.3 Regulatory Requirements ......................................................................................... 3 3.0 Receptor Information ....................................................................................................... 5 4.0 Regional Geology and Hydrogeology .............................................................................. 7 5.0 Site Geology and Hydrogeology ...................................................................................... 8 6.0 Groundwater Monitoring Results ..................................................................................... 9 7.0 Assessment Work Plan ..................................................................................................10 7.1 Ash and Soil Sampling Plan .....................................................................................10 7.1.1 Boring and Sampling Methods .......................................................................10 7.1.2 Proposed Soil and Ash Sampling Locations and Depths ...............................11 7.2 Groundwater Sampling Plan ....................................................................................12 7.2.1 Well Installation and Development .................................................................13 7.2.2 Hydrogeologic Evaluation ..............................................................................14 7.2.3 Groundwater Sampling ..................................................................................14 7.3 Surface Water Sampling Plan ..................................................................................14 7.3.1 Ash Basin Surface Water Samples ................................................................14 7.3.2 Seep Samples ...............................................................................................14 7.3.2 Suck Creek Surface Water Samples ..............................................................15 7.4 Site Hydrogeologic Conceptual Model .....................................................................15 7.5 Site-Specific Background Concentrations ................................................................15 7.6 Groundwater Model .................................................................................................15 8.0 Proposed Schedule ........................................................................................................17 9.0 References .....................................................................................................................18 Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin TABLE OF CONTENTS ii Appendix A – Notice of Regulatory Requirements Letter from John E. Skvarla, III, Secretary, State of North Carolina, To Paul Newton, Duke Energy, dated August 13, 2014. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin TABLE OF CONTENTS iii List of Figures 1. Site Location Map 2. Site Layout Map 3. Proposed Well and Sample Locations List of Tables 1. Groundwater Monitoring Requirements 2. Exceedances of 2L Standards April 5, 2011 – August 4, 2014 3. Proposed Additional Exploration and Sampling Plan 4. Soil and Ash Parameters and Analytical Methods 5. Groundwater, Surface Water, and Seep Parameters and Analytical Methods Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin EXECUTIVE SUMMARY ES-1 Executive Summary Duke Energy Carolinas, LLC (Duke Energy), owns and operates the Cliffside Steam Station (CSS) which is located in Rutherford and Cleveland Counties at 573 Duke Power Road, Cliffside, North Carolina (Figure 1). CSS is a coal-fired, generating station that currently operates Units 5 and 6 only. The original Units 1 through 4 were retired in October 2011. Coal ash residue and other liquid discharges from CSS’s coal combustion process have been historically disposed in the station’s ash basins, which consist of the active ash basin, the Units 1-4 inactive ash basin, and the Unit 5 inactive ash basin (Figure 2). The discharge from the active ash basin is permitted by the North Carolina Department of Environment and Natural Resources (NCDENR) Division of Water Resources (DW R) under the National Pollutant Discharge Elimination System (NPDES) Permit NC0005088. On August 13, 2014, NCDENR issued a Notice of Regulatory Requirements (NORR) letter to Duke Energy, pursuant to Title 15A North Carolina Administrative Code (15A NCAC) Chapter 02L.0106. The NORR stipulates that for each coal-fueled plant owned, Duke Energy will complete a Groundwater Assessment Work Plan (Work Plan) for conducting a comprehensive site assessment (CSA) and complete a receptor survey. In accordance with the requirements of the NORR, HDR is in the process of completing a receptor survey to identify all receptors within a 0.5-mile radius (2,640 feet) of the CSS ash basin compliance boundary. This receptor survey will also address the requirements of the General Assembly of North Carolina Session 2013 Senate Bill 729 Ratified Bill (SB 729). Soil and groundwater sampling will be performed to provide information pertaining to the horizontal and vertical extent of potential soil and groundwater contamination. This will be performed by sampling existing wells, installing and sampling approximately 49 additional nested pairs of shallow and deep wells, and collecting soil and ash samples. This work will provide information on the chemical and physical characteristics of site soils and ash, as well as the geological and hydrogeological features of the site that influence groundwater flow and direction and transport of constituents from the ash basin and ash storage areas. Samples of ash basin water will be collected and used to evaluate potential impacts to groundwater and surface water. In addition, water samples will be collected from seep sample locations identified in July 2014 (as part of Duke Energy’s NPDES permit renewal application) to evaluate potential impacts to surface water. The information obtained through implementation of this W ork Plan will be utilized to prepare a CSA report in accordance with the requirements of the NORR. If it is determined that additional investigations are required during the review of existing data or data developed from this assessment, Duke Energy and HDR will notify the NCDENR regional office prior to initiating additional sampling or investigations. HDR will also perform an assessment of risks to human health or safety and to the environment. This assessment will include the preparation of a conceptual site model illustrating potential pathways from the source to possible receptors. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin INTRODUCTION 1 1.0 Introduction Duke Energy Carolinas, LLC (Duke Energy), owns and operates the Cliffside Steam Station (CSS), which is located in Rutherford and Cleveland Counties at 573 Duke Power Road, Cliffside, North Carolina (Figure 1). CSS is a coal-fired, generating station that currently operates Units 5 and 6 only. The original Units 1 through 4 were retired in October 2011. Coal ash residue and other liquid discharges from CSS’s coal combustion process have been historically disposed in the station’s ash basins, which consist of the active ash basin, the Units 1-4 inactive ash basin, and the Unit 5 inactive ash basin (Figure 2). The discharge from the active ash basin is permitted by the North Carolina Department of Environment and Natural Resources (NCDENR) Division of Water Resources (DW R) under the National Pollutant Discharge Elimination System (NPDES) Permit NC0005088. On August 13, 2014, NCDENR issued a Notice of Regulatory Requirements (NORR) letter to Duke Energy, pursuant to Title 15A North Carolina Administrative Code (15A NCAC) Chapter 02L.0106. The NORR stipulates that for each coal-fueled plant owned, Duke Energy will conduct a comprehensive site assessment (CSA) which includes a Groundwater Assessment Work Plan (Work Plan) and a receptor survey. In accordance with the requirements of the NORR, HDR is in the process of completing a receptor survey to identify all receptors within a 0.5-mile radius (2,640 feet) of the CSS ash basin compliance boundary. The NORR letter is included as Appendix A. On behalf of Duke Energy, HDR has prepared this proposed Work Plan for performing the groundwater assessment as prescribed in the NORR. If it is determined that additional investigations are required during the review of existing data or data developed from this assessment, Duke Energy and HDR will notify the NCDENR regional office prior to initiating additional sampling or investigations. HDR will also perform an assessment of risks to human health or safety and to the environment. This assessment will include the preparation of a conceptual site model illustrating potential pathways from the source to possible receptors. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin SITE HISTORY 2 2.0 Site History 2.1 Plant Description CSS is a coal-fired, electricity-generating facility located along the south bank of the Broad River in Rutherford and Cleveland Counties at 573 Duke Power Road, Cliffside, North Carolina (Figure 1). CSS currently operates Units 5 and 6 only. The original Units 1-4 were retired in October 2011. The site is located on the southern bank of the Broad River and lies in both Cleveland and Rutherford Counties. The site is located north of McCraw Road and the surrounding area generally consists of residential properties, undeveloped land, and the Broad River. McCraw Road runs from northwest to southeast in the vicinity of the site. 2.2 Ash Basin Description The station has one active ash basin and two inactive ash basins; the Units 1-4 inactive ash basin, and the Unit 5 inactive ash basin as shown on Figure 1. The active ash basin and the Units 1-4 inactive ash basin are located in Cleveland County to the east and southeast of the CSS. The Unit 5 inactive ash basin is located in Rutherford County west of the CSS. The active ash basin is located approximately 1,700 feet to the east-southeast of CSS adjacent to the Broad River as shown on Figure 2. The active ash basin is impounded by earthen dikes located between the west portion of the basin and Suck Creek and between the northeast portion of the basin and the Broad River. The waste boundary associated with the active ash basin is approximately 117 acres in area. The approximate maximum pond elevation of the active ash basin is 770 feet. The main section of the pond is operated below 765 feet to have extra storage capacity during a heavy flood event. The two ash storage areas are located adjacent to the active ash basin. The ash located in these storage areas was removed from the active ash basin. The Units 1-4 inactive ash basin is located approximately 400 feet to the southeast of the retired Units 1-4 and approximately 1,300 feet to the northeast of Unit 6, adjacent to the Broad River (Figure 2). The Units 1-4 inactive ash basin is impounded by an earthen dike located along the north and northeast side of the basin. The waste boundary associated with the Units 1-4 inactive ash basin is approximately 14.5 acres in area. The Unit 5 inactive ash basin is located approximately 1,000 feet to the southwest of Unit 5 and approximately 1,000 feet west of Unit 6, south of the Broad River (Figure 2). The Unit 5 inactive ash basin is impounded by two earthen dikes located along the north and northeast sides of the basin. The waste boundary associated with the Unit 5 inactive ash basin is approximately 58 acres in area. The ash basin system has been an integral part of the station’s wastewater treatment system which has received inflows from the ash removal system, station yard drain sump, stormwater flows, and station wastewater. Currently, the inflows from the ash removal system and the Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin SITE HISTORY 3 station yard drainage basin are discharged through High Density Polyethylene Pipe (HDPE) sluice lines into the active ash basin. The inflows are variable based on Unit 5 and Unit 6 operations. Effluent from the ash basin system is discharged from the active basin to the Broad River through a concrete discharge tower located in the northeast portion of the basin. The concrete discharge tower drains through a 42-inch reinforced concrete pipe (RCP) into a rip-rap lined channel that discharges to the Broad River. The ash basin pond elevation is controlled by the use of concrete stop logs. 2.3 Regulatory Requirements The NPDES program regulates wastewater discharges to surface waters, to ensure that surface water quality standards are maintained. CSS is permitted to discharge wastewater under NPDES Permit NC0005088, which authorizes discharge from the active ash basin (Outfall 002) to the Broad River in accordance with effluent limitations, monitoring requirements, and other conditions set forth in the permit. The Yard Drainage Basin has an emergency permitted outfall (Outfall 002A) in the event the pumps cannot pump the water from the Yard Drainage Basin to the active ash basin. Treated flue gas desulfurization (FGD) wastewater (Outfall 004) is routed through an internal outfall and drains to the Yard Drainage Basin, which then pumps to the active ash basin. The NPDES permitting program requires that permits be renewed every five years. The most recent NPDES permit renewal at CSS became effective on March 1, 2011, and expires on July 31, 2015. In addition to surface water monitoring, the NPDES permit requires groundwater monitoring. Groundwater monitoring has been performed in accordance with the permit conditions beginning in April 2011. NPDES Permit Condition A (11), Version 1.1, dated June 15, 2011, lists the groundwater monitoring wells to be sampled, the parameters and constituents to be measured and analyzed, and the requirements for sampling frequency and reporting results. These requirements are provided in Table 1. The compliance boundary for groundwater quality at the CSS ash basin site is defined in accordance with Title 15A NCAC 02L .0107(a) as being established at either 500 feet from the waste boundary or at the property boundary, whichever is closer to the waste. The location of the ash basin compliance monitoring wells, the ash basin waste boundary, and the compliance boundary are shown on Figure 2. The locations for the compliance groundwater monitoring wells were approved by the NCDENR DWR Aquifer Protection Section (APS). All compliance monitoring wells included in Table 1 are sampled three times per year (in April, August, and December). Analytical results are submitted to the DWR before the last day of the month following the date of sampling for all compliance monitoring wells. The compliance groundwater monitoring system for the CSS ash basin consists of the following monitoring wells: MW -20D, MW -20DR, MW -21D, MW -22DR, MW-23D, MW-23DR, MW -24D, Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin SITE HISTORY 4 MW -24DR, and MW -25DR (shown on Figures 2 and 3). The compliance monitoring wells were installed by Duke Energy in 2010 and 2011. One or more groundwater quality standards (2L Standards) have been exceeded in groundwater samples collected at monitoring wells MW -20D, MW -20DR, MW-21D, MW -22DR, MW -23D, MW -23DR, MW-24D, MW -24DR, and MW-25DR. Exceedances have occurred for chromium, iron, manganese, pH, sulfate, and total dissolved solids (TDS). Table 2 presents exceedances measured at each of these groundwater monitoring wells from April 2011 through August 2014. Monitoring wells MW-24D and MW -24DR are considered by Duke Energy to represent background water quality as both wells are located south of the active ash basin (i.e., upgradient). Monitoring wells MW -21D and MW-22DR are located to the east of the active ash basin. Monitoring wells MW -20D and MW-20DR are located to the north of the ash basin main dam. MW -23D and MW -23DR are located west of the active ash basin and MW -25DR is located to the north of the ash basin across the Broad River. The locations of these compliance monitoring wells are shown on Figure 2. Monitoring wells MW -20D, MW -21D, MW -23D, and MW -24D were installed by rotary drilling methods using hollow stem augers with the well screen placed at the zone where saprolite transitions to competent bedrock (i.e., the transition zone). Upon auger refusal, the transition zone well borings were extended approximately 10 feet into competent bedrock using HQ-sized rock coring techniques. The well screens were placed to extend both above and below the top of the saprolite/competent bedrock interface. Total depths for the transition wells ranged from 21.5 feet below ground surface (bgs) in MW -20D and MW -21D to 53.4 feet bgs in MW -24D. The screen lengths ranged from 5 feet to 20 feet.1 With the exception of monitoring wells MW -24D and MW-24DR, the ash basin monitoring wells were installed at or within the CSS ash basin compliance boundary. Monitoring wells MW -24D and MW24DR are located approximately 150 feet outside of the most southern portion of the compliance boundary. Several monitoring wells were installed by Duke Energy in 1995/1996, 2005, and 2007 as part of the voluntary monitoring system for groundwater near the ash basin. Monitoring wells CLMW -1, CLMW -2, CLMW -3S, CLMW -3D, CLMW-4, CLMW-5S, and CLMW-6 were installed in 1995 and 1996. Monitoring wells MW -8S, MW-10S, and MW -11S were installed in 2005. Monitoring wells MW -2D, MW -4D, MW -8D, MW -10D, and MW-11D were installed in 2007. In addition, MW -2D-A was installed in 2011 to replace MW -2D. No groundwater samples are currently collected from these wells under the compliance monitoring program. The locations of the existing voluntary monitoring wells are shown on Figure 3. 1 Ash Basin Monitoring Well Installation Report, Cliffside Steam Station, MACTEC Project No. 6228-10- 5371, May 6, 2011. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin RECEPTOR INFORMATION 5 3.0 Receptor Information The August 13, 2014, NORR states: No later than October 14th, 2014 as authorized pursuant to 15A NCAC 02L .0106(g), the DWR is requesting that Duke perform a receptor survey at each of the subject facilities and submitted to the DWR. The receptor survey is required by 15A NCAC 02L .0106(g) and shall include identification of all receptors within a radius of 2,640 feet (one-half mile) from the established compliance boundary identified in the respective National Pollutant Discharge Elimination System (NPDES) permits. Receptors shall include, but shall not be limited to, public and private water supply wells (including irrigation wells and unused or abandoned wells) and surface water features within one-half mile of the facility compliance boundary. For those facilities for which Duke has already submitted a receptor survey, please update your submittals to ensure they meet the requirements stated in this letter and referenced attachments and submit them with the others. If they do not meet these requirements, you must modify and resubmit the plans. The results of the receptor survey shall be presented on a sufficiently scaled map. The map shall show the coal ash facility location, the facility property boundary, the waste and compliance boundaries, and all monitoring wells listed in the respective NPDES permits. Any identified water supply wells shall be located on the map and shall have the well owner's name and location address listed on a separate table that can be matched to its location on the map. In accordance with the requirements of the NORR, HDR is in the process of completing a receptor survey for CSS to identify all receptors within a 0.5-mile radius (2,640 feet) of the CSS ash basin compliance boundary to be submitted to NCDENR no later than October 1, 2014. This receptor survey will also address the requirements of SB 729. The receptors include, but are not limited to, public and private water supply wells (including irrigation wells and unused or abandoned wells) and surface water features within a 0.5-mile radius of the CSS ash basin compliance boundary. The compliance boundary for groundwater quality, in relation to the ash basin, is defined in accordance with Title 15A NCAC 02L .0107(a) as being established at either 500 feet from the waste boundary or at the property boundary, whichever is closer to the source. The receptor survey will include a map showing the coal ash facility location, the facility property boundary, the waste and compliance boundaries, and all monitoring wells listed in the NPDES permit. The identified water supply wells will be located on the map and the well owner's name and location address are listed on a separate table that can be matched to its location on the map. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin RECEPTOR INFORMATION 6 During completion of the CSA, HDR will update the receptor information as necessary, in general accordance with the CSA receptor survey requirements. If necessary, an updated receptor survey will be submitted with the CSA report. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin REGIONAL GEOLOGY AND HYDROGEOLOGY 7 4.0 Regional Geology and Hydrogeology North Carolina is divided into distinct regions by portions of three physiographic provinces: the Atlantic Coastal Plain, Piedmont, and Blue Ridge (Fenneman, 1938). CSS is located within the Piedmont zone, one of several northeast-trending geologic belts of the southern crystalline Appalachians. The zone lies between the Charlotte Terrane of the Carolina zone to the east and the Blue Ridge Terrane to the west. Rocks in the Piedmont zone have undergone intense metamorphism, folding, faulting, and igneous intrusion. The Piedmont zone is a fault-bounded composite stack of thrust sheets containing a variety of gneisses, schists, amphibolites, sparse ultramafic bodies, and intrusive granitoids (Horton and McConnell, 1991; Nelson and others, 1998). The general structure within the zone is characterized by irregular foliation of low dip and folds transverse to the northeast regional trend. The stratified rocks consist of thinly layered mica schist and biotite gneiss that are interlayered with lesser amounts of amphibolite, calc-silicate rocks, hornblende gneiss, and quartzite. Protoliths of these rocks were largely sedimentary and in part volcanic. Large and small masses of granite and granodiorite are present throughout the belt and form concordant to semi-concordant bodies in the country rock. Some of these granitoid bodies are gneissic and are probably older than the poorly foliated to non-foliated facies. Small, ultramafic masses are present along the eastern and western edges of the belt. The rocks of the central core of the Western Piedmont zone are in the sillimanite zone of amphibolite metamorphism with the flanks primarily in the staurolite-kyanite zone (Butler, 1991). In the Piedmont zone, a variable thickness and degree of soil, saprolite, and weathered rock, referred to as regolith, typically overlie crystalline bedrock. The degree of weathering typically decreases with depth with a thoroughly weathered and structureless material at the surface termed residuum. The residuum grades into a relatively coarse-grained material that retains the structure of the parent bedrock and is termed saprolite (can extend to greater than 150 feet in depth below the ground surface). Beneath the saprolite, partially weathered bedrock occurs with depth until sound bedrock is encountered. A transition zone may occur at the base of the regolith between the soil-saprolite and the unweathered bedrock. This transition zone of partially weathered rock is a zone of relatively high permeability compared to the overlying soil-saprolite and the underlying bedrock (LeGrand 2004). Groundwater flow paths in the Piedmont are almost invariably restricted to the zone underlying the topographic slope extending from a topographic divide to an adjacent stream. LeGrand describes this as the local slope aquifer system. Under natural conditions, the general direction of groundwater flow can be approximated from the surface topography (LeGrand 2004). Groundwater recharge in the Piedmont is derived entirely from infiltration of local precipitation. Groundwater recharge occurs in areas of higher topography (i.e., hilltops) and groundwater discharge occurs in lowland areas bordering surface water bodies, marshes, and floodplains (LeGrand 2004). Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin SITE GEOLOGY AND HYDROGEOLOGY 8 5.0 Site Geology and Hydrogeology Based on a review of soil boring and monitoring well installation logs provided by Duke Energy, subsurface stratigraphy consists of the following material types: fill, alluvium, residuum, saprolite, partially weathered rock (PWR), and bedrock. In general, residuum, PWR and bedrock were encountered beneath most areas of the site. Alluvium was encountered in borings advanced east of Suck Creek and north of the Broad River. Bedrock was consistently encountered at varying depths across the site. The general stratigraphic units, in sequence from the ground surface down to boring termination, are defined as follows:  Fill – Fill material generally consisted of re-worked sands and silts that were borrowed from one area of the site and re-distributed to other areas. Fill was used in the construction of dikes and presumably as cover for the ash storage area.  Ash – Although previous exploration activities, for which Duke Energy provided boring logs, did not evaluate ash management areas of the site, ash is expected to be present within the ash management areas (i.e., active ash basin, two inactive ash basins, and the ash storage areas).  Alluvium – Alluvium is unconsolidated soil and sediment that has been eroded and re- deposited by streams and rivers. Alluvium may consist of a variety of materials ranging from silts and clays to sands and gravels. Alluvium was encountered in two boring locations east of Suck Creek and north of the Broad River. Alluvium in these borings was described as orange, tan, or brown fine- to coarse-grained sand.  Residuum – Residuum is in-place weathered soil that was encountered at varying thickness (5 feet to 58 feet) across the site. Residuum was described as gray, orange, tan, red, or brown micaceous fine-grained to coarse-grained sand or fine-grained sandy silt.  Saprolite – Saprolite is soil developed by in-place weathering of rock. The primary distinction from residuum is that saprolite typically retains some structure (e.g., mineral banding) from the parent rock. Saprolite was encountered as a relatively thick layer (25 feet) in borings completed along the southern and western property boundaries. Saprolite was described as reddish yellow to brown micaceous, stiff silty fine-grained to medium-grained sand, silty clay and clayey silt with relict rock structure. Partially Weathered Rock (PWR) – PW R occurs between the saprolite and bedrock consisting of saprolite and rock remnants. This unit was encountered in most boring locations and was described as orange, tan, gold, brown, maroon, or black micaceous fine to coarse sand with rock fragments. Bedrock – Bedrock was encountered across the site. Bedrock was encountered as shallow as 18 feet below ground surface (bgs) in borings on the eastern extent of the site and as deep as 58 feet bgs in a boring located on the southern extent of the site. Bedrock was described as gray to bluish gray garnetiferous biotite gneiss with white to gray quartzite seams. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin GROUNDWATER MONITORING RESULTS 9 6.0 Groundwater Monitoring Results From April 2011 through August 2014, the compliance groundwater monitoring wells at CSS have been sampled a total of 11 times. During this period, these monitoring wells were sampled in:  April 2011  August 2011  December 2011  April 2012  August 2012  December 2012  April 2013  August 2013  December 2013  April 2014  August 2014 With the exception of chromium, iron, manganese, pH, sulfate, and total dissolved solids (TDS) the results for all monitored parameters and constituents were less than the 2L Standards. Table 2 lists the range of 2L Standard exceedances for chromium, iron, manganese, pH, sulfate, and TDS for the sampling events listed above. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 10 7.0 Assessment Work Plan Soil and groundwater sampling will be performed to provide information pertaining to the horizontal and vertical extent of potential soil and groundwater contamination. Based on readily available site background information, and dependent upon accessibility, HDR anticipates collecting soil and/or ash samples during installation of approximately 49 nested monitoring well pairs (shallow and deep). Groundwater samples will be collected from the proposed monitoring wells. The proposed well and boring locations are listed in Table 3 and shown on Figure 3. HDR may also resample select existing monitoring wells to supplement groundwater quality data. This work will provide additional information on the chemical and physical characteristics of site soils and ash, as well as the geological and hydrogeological features of the site that may influence groundwater flow and transport of constituents from the ash basin. Samples of ash basin water will also be collected and used to evaluate potential impacts to groundwater and surface water. Surface water samples will also be collected from Suck Creek at the approximate locations shown on Figure 3. If conditions allow for representative sampling, water samples will be collected from seep sample locations (S-1 through S-11) identified in July 2014 (as part of Duke Energy’s NPDES permit renewal application) to evaluate potential impacts to surface water. The seep sample locations identified as part of the NPDES permit renewal were a combination of seeps and surface water sample locations. For consistency and comparison of historical analytical data, the nomenclature for these samples will remain the same. A summary of the proposed exploration plan, including estimated sample quantities and soil boring and monitoring well depths, is presented in Table 3. If it is determined that additional investigations are required during the review of existing data or data developed from this assessment, Duke Energy and HDR will notify the NCDENR regional office prior to initiating additional sampling or investigations. 7.1 Ash and Soil Sampling Plan 7.1.1 Boring and Sampling Methods Prior to drilling each boring, all down-hole equipment and tools will be cleaned by washing with high-pressure hot water. A designated remote cleaning area will be established in the field. Water for cleaning will be obtained from a tap or hydrant (to be designated) at CSS, or supplied by the drilling contractor from an off-site source. Cleaning water will not require collection, treatment, or disposal. Borings will be advanced using hollow stem auger or roller cone drilling techniques to facilitate collection of down-hole data. Standard Penetration Testing (SPT) (ASTM D 1586) and split- spoon sampling will be performed at 2.5-foot to 5-foot increments using an 18-inch split-spoon sampler. The sampler will be decontaminated with a non-phosphate detergent wash between sampling depths. Ash and soil samples will be collected by the Project Scientist/Engineer. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 11 Borings will be logged by the Project Scientist/Engineer and ash/soil samples will be observed, visually classified, and photographed in the field for origin, consistency/relative density, color, and soil type in accordance with the Unified Soil Classification System (ASTM D2487/D2488). Samples will be identified with a unique boring number and approximate collection depth (e.g., AB-1 (20-25’)). Sample containers will be provided by HDR’s contracted laboratory prior to commencement of the on-site investigation. Samples will be delivered to the analytical laboratory in time to extract the samples within their specified hold times (to be provided by the laboratory). HDR will provide the name, phone number, and email address of the laboratory project manager to facilitate sample analysis coordination. Laboratory constituents and methods for analysis of environmental ash and soil samples are presented in Table 5. Boring locations will be surveyed for horizontal and vertical control upon completion of the field exploration program. 7.1.2 Proposed Soil and Ash Sampling Locations and Depths HDR anticipates collection of soil and ash samples for laboratory analysis at 8 locations within the Unit 5 inactive ash basin waste boundary (i.e., from monitoring well borings designated as U5-1 through U5-8), 4 locations within the Units 1-4 inactive ash basin waste boundary (designated as IB-1 through IB-4), 5 locations within the active ash basin waste boundary (designated as AB-1 through AB-5), and 4 locations within and immediately down gradient of the ash storage areas (designated as AS-1 through AS-4). The borings located within these ash management areas will extend approximately 20 feet below the ash/native soil interface or to refusal, whichever is encountered first. In addition, HDR anticipates collection of soil samples at four background locations (designated as BG-1, BG-2, MW -30, and MW-32). Soil samples will not be collected for laboratory analysis during installation of monitoring wells located outside the Unit 5 inactive ash basin, Units 1-4 inactive ash basin, and active ash basin waste boundaries (designated as GWA-series wells) and during installation of the Unit 5 inactive ash basin compliance groundwater monitoring wells (except for MW -30S/D and MW -32S/D). Proposed boring locations are shown on Figure 3. CONSTITUENT SAMPLING AND ANALYSES In general, ash is expected to be encountered in U5-series, IB-series, AB-series, and AS-series borings. Where present, ash samples will be collected from shallow and deeper vertical intervals to evaluate variations in type (e.g., fly ash or bottom ash) and chemical profile of the ash. In locations where ash thickness is expected to be greater than 30 feet, a third ash sample may be collected from a depth mid-way between the shallow and deeper intervals in a particular boring. Shallow ash samples will be collected from the 4-foot to 5-foot intervals and deeper ash samples will be collected from the 1-foot to 2-foot intervals overlying the ash/native soil interface. The depth of deeper ash samples is expected to vary based on ash thickness at each specific boring location. Ash samples will be analyzed by HDR’s subcontract laboratory for total and leachable inorganic compounds, as presented in Table 4. Soil samples will be collected below the ash/native soil interface and from the terminus of each boring to characterize soil quality beneath the ash management areas. Soil samples will be Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 12 analyzed by HDR’s subcontract laboratory for total inorganics using the same constituents list proposed for the ash samples. INDEX PROPERTY SAMPLING AND ANALYSES Physical characteristics of ash and soil will be tested both in the field and in the laboratory to provide data for use in groundwater modeling. The location and depth of the index property samples will be based on site-specific geology and decided upon in the field. Based on HDR’s current understanding of site-specific geology, five hydrostratigraphic units are present on-site. In general, a minimum of five in-situ permeability tests, either falling or constant head tests, will be performed in each of the hydrostratigraphic units. In addition, a minimum of five packer tests will be performed in bedrock. Laboratory testing of soil and ash collected from SPT samples will include tests for grain size (with hydrometer), specific gravity, and porosity (calculation). 7.2 Groundwater Sampling Plan Groundwater samples will be collected from the proposed 49 nested well pairs shown on Figure 3. Groundwater quality data may be supplemented through evaluation of historical data or re-sampling of select existing monitoring wells. The purpose and anticipated construction details of the proposed monitoring wells are as follows:  U5-series Wells – One shallow well screened across the water table (10-foot to 15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. The U5-series well locations were selected to provide water quality data in and beneath the Unit 5 inactive ash basin.  IB-series Wells – One shallow well screened across the water table (15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. The IB-series well locations were selected to provide water quality data in and beneath the Units 1-4 inactive ash basin.  AB-series Wells – One shallow well screened across the water table (10-foot to 15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. The AB-series well locations were selected to provide water quality data in and beneath the active ash basin.  AS-series Wells – One shallow well screened across the water table (10-foot to 15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. The AS-series well locations were selected to provide water quality data in, beneath, and immediately down gradient of the ash storage areas.  GWA-series Wells – One shallow well screened across the water table (15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. The GWA-series well locations were selected to provide water quality data beyond the waste boundary for Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 13 use in groundwater modeling (i.e., to evaluate the horizontal and vertical extent of potentially impacted groundwater around the ash basins).  MW -30S/D, MW -32S/D, MW -34S/D, MW-36S/D, MW -38S/D, MW-40S/D, and MW - 42S/D Wells – One shallow well screened across the water table (15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. These wells were proposed in the station’s July 2014 NPDES permit renewal application and will be installed as part of this assessment work.  BG-series Wells – One shallow well screened across the water table (15-foot well screen) and one deep well screened in the transition zone (5-foot well screen in weathered rock below auger refusal) will be installed at each location. Note that Unit 5 inactive ash basin compliance wells MW -30S/D and MW -32S/D are considered to be background wells at this time. The background well locations were selected to provide additional physical separation from possible influence of the ash basin on groundwater. These wells will also be useful in the statistical analysis to determine the site-specific background water quality concentrations (SSBCs). 7.2.1 Well Installation and Development SHALLOW MONITORING WELLS At each monitoring well location specified on Figure 3 with an “S” qualifier in the well name (e.g., AB-1S), a shallow well will be constructed with a 2-inch-diameter, schedule 40 PVC screen and casing. Each of these wells will have a 10-foot to 15-foot well screen (0.010-slot) set to bracket the water table at the time of installation. DEEP MONITORING WELLS At each monitoring well location specified on Figure 3 with a “D” qualifier in the well name (e.g., AB-1D), a double-cased deep well will be constructed with a 6-inch-diameter PVC outer casing and a 2-inch-diameter PVC inner casing and well screen. The purpose of installing cased wells at the site is to restrict vertical mixing within the shallow and deeper portions of the unconfined aquifer during well installation. Outer well casings (6-inch casing) will be advanced to auger refusal and set approximately 1 foot into PWR. Note that location-specific subsurface geology will dictate actual casing depths on a per-well basis. Air rotary drilling will be used to advance the borehole a minimum of 10 feet into PWR or bedrock with the intent of setting a 5-foot well screen at least 10 feet below the bottom of the outer casing. All newly installed monitoring wells will be developed using appropriate measures (e.g., agitation, surging, pumping, etc.). Water quality parameters (specific conductance, pH, temperature, and turbidity) will be measured and recorded during development and should stabilize before development is considered complete. Development will continue until development water is visually clear (target < 50 Nephelometric Turbidity Units (NTU) Turbidity) and sediment free. Following development, sounding the bottom of the well with a water level meter should indicate a “hard” (sediment free) bottom. Development records will be prepared under the direction of the Project Scientist/Engineer and will include development method(s), water volume removed, and field measurements of temperature, pH, conductivity, and turbidity. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 14 7.2.2 Hydrogeologic Evaluation Hydraulic conductivity (slug) tests will be completed in select monitoring wells under the direction of the Project Scientist/Engineer. Slug tests will be performed to meet the requirements of the NCDENR Memorandum titled, “Performance and Analysis of Aquifer Slug Tests and Pumping Tests Policy, dated May 31, 2007.” Water level change during the slug tests will be recorded by a data logger. In addition, approximately 5 to 10 packer tests will be conducted during installation of the Type III wells to facilitate permeability testing of the upper five feet of rock. 7.2.3 Groundwater Sampling Subsequent to monitoring well installation and development, each newly installed well will be sampled using low-flow sampling techniques. During low-flow purging and sampling, groundwater is pumped into a flow-through chamber at flow rates that minimize or stabilize water level drawdown within the well. Indicator parameters are measured over time (usually at 5-minute intervals). When parameters have stabilized within ±0.2 pH units and ±10 percent for temperature, conductivity, and dissolved oxygen (DO), and ±10 millivolts (mV) for oxidation reduction potential (ORP) over three consecutive readings, representative groundwater has been achieved for sampling. Turbidity levels of 10 NTU or less will be targeted prior to sample collection. Groundwater samples will be analyzed by a North Carolina certified laboratory for the constituents included in Table 5. Select constituents may be analyzed for total and dissolved concentrations. 7.3 Surface Water Sampling Plan 7.3.1 Ash Basin Surface Water Samples Surface water samples will be collected from the approximate open water locations in the Unit 5 inactive ash basin and the active ash basin shown on Figure 3. At each open water location, two water samples will be collected – one sample close to the surface (i.e., 0 to 1 foot from surface) and one sample at the approximate middle depth of the water body. The middle depth sample will vary based on the water level in the water body. In areas where the water body is less than 5 feet deep, one water sample will be collected from the location at the approximate middle depth of the water body. Ash basin surface water samples and surface water samples will be analyzed for the same constituents as groundwater samples listed in Table 5. Select constituents may be analyzed for total and dissolved concentrations. 7.3.2 Seep Samples Water samples will be collected from the seep sample locations shown on Figure 3 (S-1 through S-11). The seep samples will be collected for laboratory analysis of the constituents listed in Table 5. Select constituents may be analyzed for total and dissolved concentrations. Duke Energy collects surface water samples from the Broad River at upstream and downstream locations for their existing NPDES permit requirements. If seep analytical results indicate potential for impacts to the Broad River, then surface water quality data collected in the river will be reviewed. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 15 7.3.3 Suck Creek Surface Water Samples Water samples will be collected from Suck Creek upstream and downstream of the active ash basin from the locations shown on Figure 3. The creek samples will be collected for laboratory analysis of the constituents listed in Table 5. Select constituents may be analyzed for total and dissolved concentrations. 7.4 Site Hydrogeologic Conceptual Model The data obtained during the proposed assessment will be supplemented by available reports and data on site geotechnical, geologic, and hydrologic conditions to develop a site hydrogeologic conceptual model (SCM). The NCDENR document, “Hydrogeologic Investigation and Reporting Policy Memorandum,” dated May 31, 2007 (Reference 6), will be used as general guidance. In general, the SCM will utilize site information to characterize the geologic and hydrogeologic characteristics of the area of interest, and, where appropriate, lead directly to the proper construction of a groundwater flow and transport model. 7.5 Site-Specific Background Concentrations Statistical analysis will be performed to determine the SSBCs to assess whether or not exceedances can be attributed to naturally occurring background concentrations or attributed to potential contamination. Specifically, the relationship between exceedances and turbidity will be explored to determine whether or not there is a possible correlation due to naturally occurring conditions and/or well construction. 7.6 Groundwater Model Groundwater flow and chemical constituent fate and transport at the site will be modeled in three dimensions using the MODFLOW -2005 groundwater flow numeric engine and the MT3D transport model with linear isotherm sorption to predict chemical constituent concentrations over time at the compliance boundary. The groundwater model layers will be developed based on hydrogeologic properties and other data obtained during the site investigation and the SCM. The model will include the effects of recharge from precipitation. Site soil samples will be collected and used to develop site-specific distribution coefficient, Kd, terms using batch methods (US EPA Batch-type procedures for estimating soil adsorption of chemicals Technical Resource Document 530/SW-87/006-F). The selection of the initial concentrations and the predictions of the concentrations for constituents with respect to time are to be developed with consideration of the following data:  Site-specific analytical results from leach tests and from total digestion of ash samples taken at varying locations and depths within the ash basin and ash storage piles (if present).  Analytical results from appropriate groundwater monitoring wells or surface water sample locations outside of the ash basin. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin ASSESSMENT WORK PLAN 16  Analytical results from monitoring wells installed in the ash basin pore-water (screened in ash).  Published or other data on sequential leaching tests performed on similar ash. The groundwater modeling will be conducted in general conformance with the requirements of the May 31, 2007, NCDENR Memorandum titled, “Groundwater Modeling Policy.” The groundwater model and the report on the results of the groundwater modeling will be prepared by Dr. William Langley, P.E., Department of Civil and Environmental Engineering, University of North Carolina at Charlotte. Dr. Langley will perform the work under contract with HDR, and the groundwater model report will be included as an attachment to the CSA. The groundwater model will be used, as required, to evaluate options for potential corrective action in the subsequent phase of work. Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin PROPOSED SCHEDULE 17 8.0 Proposed Schedule Duke Energy will submit the CSA Report within 180 days of NCDENR approval of this Work Plan. The anticipated schedule for implementation of field work, evaluation of data, and preparation of the Work Plan is presented in the table below. Activity Start Date Duration to Complete Field Exploration Program 10 days following Work Plan approval 75 days Receive Laboratory Data 14 days following end of Exploration Program 15 days Evaluate Lab/Field Data, Develop SCM 5 days following receipt of Lab Data 30 days Prepare and Submit CSA 10 days following Work Plan approval 170 days Duke Energy Carolinas, LLC | Proposed Groundwater Assessment Work Plan Cliffside Steam Station Ash Basin REFERENCES 18 9.0 References 1. Butler, J. R., 1991, Metamorphism, p. 127-141, in Horton, J. W., Jr. and Zullo, V. A., eds., The Geology of the Carolinas: The University of Tennessee Press, Knoxville, TN, 406p. 2. Fenneman, Nevin Melancthon. “Physiography of eastern United States.” McGraw-Hill. 1938. 3. Horton, J. W., Jr. and McConnell, K. I., 1991, The western Piedmont, p. 36-58, in Horton, J. W., Jr. and Zullo, V. A., eds., The Geology of the Carolinas: The University of Tennessee Press, Knoxville, TN, 406p. 4. LeGrand, Harry E. 2004. A Master Conceptual Model for Hydrogeological Site Characterization in the Piedmont and Mountain Region of North Carolina, A Guidance Manual, North Carolina Department of Environment and Natural Resources Division of Water Quality, Groundwater Section. 5. Nelson, A. E., Horton, J. W., Jr., and Clarke, J. W., 1998, Geologic map of the Greenville 1o x 2o quadrangle, Georgia, South Carolina, and North Carolina: United States Geological Survey, Miscellaneous Investigations Series Map I-2175, Scale 1:250,000. 6. NCDENR Memorandum “Performance and Analysis of Aquifer Slug Tests and Pumping Tests Policy,” May 31, 2007. 7. NCDENR document, “Hydrogeologic Investigation and Reporting Policy Memorandum”, dated May 31, 2007. 8. US EPA Batch-type procedures for estimating soil adsorption of chemicals TechnicalResource Document 530/SW -87/006-F. Figures TAFFTJULY 31, 2014 SEPT. 19, 2014 Tables TABLE 1 – GROUNDWATER MONITORING REQUIREMENTS Well Nomenclature Constituents and Parameters Frequency Monitoring Wells: MW-20D, MW-20DR, MW-21D, MW-22DR, MW-23D, MW-23DR, MW-24D, MW-24DR, MW-25DR Antimony Chromium Nickel Thallium April, August, December Arsenic Copper Nitrate Water Level Barium Iron pH Zinc Boron Lead Selenium Cadmium Manganese Sulfate Chloride Mercury TDS TABLE 2 – EXCEEDANCES OF 2L STANDARDS APRIL 5, 2011 – AUGUST 4, 2014 Parameter Chromium Iron Manganese pH Sulfate TDS Units µg/L µg/L µg/L SU mg/L mg/L 2L Standard 10 300 50 6.5 - 8.5 250 500 Well ID Range of Exceedances MW-20D No Exceedances 3,470 – 8,620 459 – 649 No Exceedances No Exceedances No Exceedances MW-20DR No Exceedances 330 600 – 704 No Exceedances No Exceedances No Exceedances MW-21D No Exceedances No Exceedances 57 – 84 4.6 – 5.2 No Exceedances No Exceedances MW-22DR No Exceedances 3,220 – 9,890 82 – 148 5.4 – 6.4 No Exceedances No Exceedances MW-23D 14 349 – 1,130 410 – 759 No Exceedances 280 – 430 590 – 820 MW-23DR No Exceedances 828 – 1,240 51 – 54 No Exceedances No Exceedances No Exceedances MW-24D No Exceedances 382 – 2,170 87 5.1 – 5.4 No Exceedances No Exceedances MW-24DR No Exceedances 934 – 1,710 54 – 61 No Exceedances No Exceedances No Exceedances MW-25DR 45 347 – 6,610 213 5.9 – 6.5 8.7 – 9.5 No Exceedances No Exceedances TABLE 3 – ENVIRONMENTAL EXPLORATION AND SAMPLING PLAN CLIFFSIDE STEAM STATION Exploration Area Soil Borings Shallow Monitoring Wells Deep Monitoring Wells Surface Water Boring IDs Quantity Estimated Boring Depth (ft bgs) Well IDs Quantity Estimated Well Depth (ft bgs) Screen Length (ft) Well IDs Quantity Estimated Casing Depth (ft bgs) Estimated Well Depth (ft bgs) Screen Length (ft) Quantity of Locations Quantity of Samples Unit 5 Inactive Ash Basin U5-1 through U5-8 8 40-90 U5-1S through U5-8S 8 15-50 10-15 U5-1D through U5-8D 8 25-75 40-90 5 1 2 Units 1-4 Inactive Ash Basin IB-1 through IB-4 4 55-105 IB-1S through IB-4S 4 30-60 10-15 IB-1D through IB-4D 4 40-90 55-105 5 N/A N/A Active Ash Basin AB-1 through AB-5 5 65-115 AB-1S through AB-5S 5 40-80 15 AB-1D through AB-5D 5 50-100 65-115 5 3 6 Ash Storage Areas AS-1 through AS-4 4 55-105 AS-1S through AS-4S 4 30-60 10-15 AS-1D through AS-4D 4 40-90 55-105 5 N/A N/A Beyond Waste Boundary N/A 0 N/A GWA-1S through GWA-6S, GWA-10S through GWA-14S, GWA-20S through GWA-27S 19 20-50 15 GWA-1D through GWA-6D, GWA-10D through GWA-14D, GWA-20D through GWA-27D 19 30-80 45-95 5 N/A N/A Unit 5 Inactive Ash Basin Compliance Boundary 6 MW -30, MW -32, MW -34, MW -36, MW -38, MW -40, MW -42 7 45-95 MW -30S, MW -32S, MW -34S, MW -36S, MW -38S, MW -40S, MW -42S 7 20-50 15 MW -30D, MW -32D, MW -34D, MW -36D, MW -38D, MW -40D, MW -42D 7 30-80 45-95 7 N/A N/A Background BG-1 and BG-2 2 55-105 BG-1S and BG-2S 2 30-50 15 BG-1D and BG-2D 2 40-90 55-105 5 N/A N/A Notes: 1. Estimated boring and well depths based on data available at the time of work plan preparation and subject to change based on site-specific conditions in the field. 2. Laboratory analyses of soil, ash, groundwater, and surface water samples will be performed in accordance with the constituents and methods identified in Tables 4 and 5. 3. Additionally, soils will be tested in the laboratory to determine grain size (with hydrometer), specific gravity, and perm eability. 4. During drilling operations, downhole testing will be conducted to determine in-situ soil properties such as horizontal and vertical hydraulic conductivity. 5. Actual number of field and laboratory tests will be determined in field by Field Engineer o r Geologist in accordance with project specifications. 6. Unit 5 Inactive Ash Basin Compliance Boundary monitoring wells MW -30S/D and MW -32S/D are considered to be background locations. TABLE 4 – SOIL AND ASH PARAMETERS AND ANALYTICAL METHODS INORGANIC COMPOUNDS UNITS METHOD Antimony mg/kg EPA 6020 Arsenic mg/kg EPA 6020 Barium mg/kg EPA 6010 Boron mg/kg EPA 6010 Cadmium mg/kg EPA 6020 Chloride mg/kg SM4500-Cl-E Chromium mg/kg EPA 6010 Copper mg/kg EPA 6010 Iron mg/kg EPA 6010 Lead mg/kg EPA 6020 Manganese mg/kg EPA 6010 Mercury mg/kg EPA Method 7470A/7471 Nickel mg/kg EPA 6010 pH SU EPA 9045 Selenium mg/kg EPA 6020 Thallium (low level) mg/kg EPA 6020 Zinc mg/kg EPA 6010 Notes: 1. Soil samples to be analyzed for Total Inorganics using U.S. Environmental Protection Agency (USEPA) Methods 6010/6020 and pH using USEPA Method 9045, as noted above. 2. Ash samples to be analyzed for Total Inorganics using USEPA Methods 6010/6020 and pH using USEPA Method 9045; select ash samples will also be analyzed for leaching potential using Synthetic Precipitation Leaching Procedure (SPLP) Extraction Method 1312 in conjunction with USEPA Methods 6010/6020. SPLP results to be reported in units of mg/L for comparison to 2L Standards. TABLE 5 – GROUNDWATER, SURFACE WATER, AND SEEP PARAMETERS AND ANALYTICAL METHODS PARAMETER UNITS METHOD FIELD PARAMETERS pH SU Field Water Quality Meter Specific Conductance mmho/cm Field Water Quality Meter Temperature ºC Field Water Quality Meter Dissolved Oxygen mg/L Field Water Quality Meter Oxidation Reduction Potential mV Field Water Quality Meter NPDES CONSTITUENTS Antimony µg/L EPA 200.8 or 6020 Arsenic µg/L EPA 200.8 or 6020 Barium µg/L EPA 200.7 or 6010 Boron µg/L EPA 200.7 or 6010 Cadmium µg/L EPA 200.8 or 6020 Chloride mg/L EPA 300.0 Chromium µg/L EPA 200.7 or 6010 Copper mg/L EPA 200.7 or 6010 Iron µg/L EPA 200.7 or 6010 Lead µg/L EPA 200.8 or 6020 Manganese µg/L EPA 200.7 or 6010 Mercury µg/L EPA 245.1 Nickel µg/L EPA 200.7 or 6010 Nitrate as Nitrogen mg-N/L EPA 300.0 Selenium µg/L EPA 200.8 or 6020 Sulfate mg/L EPA 300.0 Thallium (low level) µg/L EPA 200.8 or 6020 Total Dissolved Solids mg/L EPA 160.1 or SM 2540C Zinc mg/L EPA 200.7 or 6010 ADDITIONAL GROUNDWATER CONSTITUENTS Alkalinity (as CaCO3) mg/L SM2320B Calcium mg/L EPA 200.7 Ferrous Iron mg/L SM4500-Fe Magnesium mg/L EPA 200.7 Potassium mg/L EPA 200.7 Sodium mg/L EPA 200.7 Sulfide mg/L SM4500S-F Total Organic Carbon mg/L SM5310 Notes: 1. Select constituents may be analyzed for total and dissolved concentrations. Appendix A Notice of Regulatory Requirements Letter from John E. Skvarla, III, Secretary, State of North Carolina, to Paul Newton, Duke Energy, dated August 13, 2014.