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HomeMy WebLinkAboutMARSHALL - GW BTV MEMO_Final_20170905TECHNICAL MEMORANDUM Date: September 5, 2017 File: 1026.18 To: Tyler Hardin (Duke Energy) Cc: Kathy Webb (SynTerra) From: Todd Plating (SynTerra) Subject: Background Threshold Values for Groundwater Marshall Steam Station- Terrell, NC An updated background groundwater dataset was provided to the North Carolina Department of Environmental Quality (NCDEQ) for Marshall Steam Station (Marshall) on May 26, 2017. Additionally, the revised Statistical Methods for Developing Reference Background Concentrations for Groundwater and Soil at Coal Ash Facilities (statistical methods document) (HDR Engineering, Inc. and SynTerra Corporation, May 2017) was provided to NCDEQ. On July 7, 2017, NCDEQ provided a response letter (Zimmerman to Draovitch, July 7, 2017) for each Duke Energy coal ash facility that identified soil and groundwater data appropriate for inclusion in the statistical analysis to determine background threshold values (BTVs) for both media. As outlined in the NCDEQ July 7, 2017 letter, Duke Energy is required to provide BTVs for both media within 60 days from receipt of the NCDEQ letter for facilities submitting Comprehensive Site Assessments (CSAs) later than October 31, 2017. BTVs for soil are provided under separate cover. The revised background groundwater dataset provided to NCDEQ on May 26, 2017 addressed comments provided in a letter by NCDEQ (Zimmerman to Draovitch, April 28, 2017). NCDEQ requested Duke Energy collect at least 10, rather than the previously planned eight, valid samples from background monitoring wells prior to determination of BTVs for constituents within each flow system. For groundwater datasets with less than 10 valid samples available for determination of BTVs, no formal upper tolerance limit (UTL) statistics could run and the provisional BTV (PBTV) for a constituent and groundwater flow system was computed to be either: 0 The highest value, or ,07 If the highest value is above an order of magnitude greater than the geometric mean of all values, then the highest value should be considered an outlier and removed from further use and the PBTV is computed to be the second highest value. NCDEQ requested that the updated background groundwater dataset exclude data from the background data set due to one or more of the following conditions: P:\Duke Energy Carolinas\ Statistics_CAMA \Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO \ Marshall \ Groundwater \ MARSHALL - GW BTV MEMO.docx Background Threshold Values for Groundwater September 5, 2017 Marshall Steam Station Page 2 of 3 0 Sample pH is greater than or equal to 8.5 standard units (S.U.) unless the regional DEQ office has determined an alternate background threshold pH for the site; '07 Sample turbidity is greater than 10 Nephelometric Turbidity Units (NTUs); 0 Result is a statistical outlier identified for background sample data presented to NCDEQ on May 26, 2017; 0 Sample collection occurred less than a minimum 60 days between sampling events; and 0 Non -detect results are greater than 2L/IMAC. Additional site -specific requirements related to the background groundwater dataset for Marshall, such as exclusion of locations not approved by NCDEQ, as outlined in the July 7, 2017 NCDEQ letter have been incorporated This technical memorandum summarizes the revised background groundwater datasets and statistically determined BTVs. Statistical determinations of BTVs were performed in accordance with the revised Statistical Methods for Developing Reference Background Concentrations for Groundwater and Soil at Coal Ash Facilities (statistical methods document) (HDR Engineering, Inc. and SynTerra Corporation, May 2017). GROUNDWATER BACKGROUND DATA The current background monitoring well network consists of wells installed within three flow zones - shallow, deep flow zone, and bedrock. Well locations are presented on Figure 1. Background datasets provided to NCDEQ on May 26, 2017 were revised based on input from NCDEQ in the July 7, 2017 letter. The revised background datasets for each flow system used to statistically determine naturally occurring concentrations of inorganic constituents in groundwater are provided in Table 1. The following sections summarize the refined background datasets along with the results of the statistical evaluations for determining BTVs. SHALLOW Seven wells -GWA-4S, GWA-5S, GWA-6S, GWA-8S, GWA-12S, MS-10, and MW-4 - monitor background groundwater quality within the surficial flow zone. In the July 7, 2017 letter, NCDEQ concurred with the data proposed for the shallow flow zone background dataset. Samples collected less than 60 days between sampling events, statistical outliers, and invalid data have been omitted from use in statistical determinations. The revised shallow background dataset is presented in Table 1. The shallow background groundwater dataset meets the minimum requirement of 10 samples for all constituents. BTVs were calculated for constituents monitored within the shallow flow system using formal UTL statistics and are presented in Table 2. P:\Duke Energy Carolinas\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO \ Marshall \ Groundwater \ MARSHALL - GW BTV MEMO.docx Background Threshold Values for Groundwater September 5, 2017 Marshall Steam Station Page 3 of 3 DEEP FLOW ZONE Four wells -GWA-41), GWA-51), GWA-61), and GWA-81) - monitor background groundwater quality within the deep flow zone. In the July 7, 2017 letter, NCDEQ identified GWA-12D as not appropriate for use in determining BTVs. Recent attempts to redevelop well GWA-12D have been made due to water quality issues; re-evaluation as a background location is warranted. The deep flow zone background groundwater dataset meets the minimum requirement of 10 samples for all constituents after excluding GWA-121). Prior to statistical determinations, the revised background dataset was re -screened for outliers to adjust for the removal of samples. Table 1 presents the revised background dataset for the deep flow zone. BTVs were calculated for constituents monitored within the deep flow zone using formal UTL statistics. BTVs for the deep flow zone are presented in Table 2. BEDROCK Three wells-BG-3BR, GWA-12BR, and MW-41) -monitor background groundwater quality within the fractured bedrock. In the July 7, 2017 letter, NCDEQ identified BG-1BR as not appropriate for use in determining BTVs. Well BG-1BR was recentally reinstalled due to water quality issues and requires re-evaluation as a background location for bedrock. The bedrock dataset meets the minimum requirement of 10 samples for all constituents. Prior to statistical determinations, the revised background dataset was re -screened for outliers to adjust for the removal of samples. The revised background dataset is presented in Table 1. BTVs were calculated for constituents monitored within fractured bedrock using formal UTL statistics. BTVs for fractured bedrock are presented in Table 2. LIST OF FIGURES: Figure 1 Well Location Map LIST OF TABLES: Table 1 Background Groundwater Results through March 2017 Table 2 Background Threshold Values for Groundwater P:\Duke Energy Carolinas\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO \ Marshall \ Groundwater \ MARSHALL - GW BTV MEMO.docx Background Threshold Values for Groundwater September 5, 2017 Marshall Steam Station FIGURE P:\Duke Energy Carolinas\ Statistics_CAMA \Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO \ Marshall \ Groundwater \ MARSHALL - GW BTV MEMO.docx Background Threshold Values for Groundwater September 5, 2017 Marshall Steam Station TABLES P:\Duke Energy Carolinas\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO \ Marshall \ Groundwater \ MARSHALL - GW BTV MEMO.docx TABLE 1 BACKGROUND GROUNDWATER RESULTS THROUGH MARCH2O17 MARSHALL STEAM STATION DUKE ENERGY CAROLINAS, LLC, TERRELL, NC Analytical Parameter pH Turbidity Alkalinity Aluminum Antimony Arsenic Barium Beryllium Bicarbonate Alkalinity Boron Cadmium Calcium Carbonate Alkalinity Chloride Chromium (VI) r Chromium Cobalt Copper Iron Lead Magnesium Reporting Units S.U. NTU mg/L ug/L ug/L ug/L ug/L ug/L mg/L ug/L ug/L mg/L mg/L mg/L ug/L ug/L ug/L ug/L ug/L ug/L mg/L SSA NCAC 02L Standard 6.5-8.5 NE NE NE 1* 10 700 4* NE 700 2 NE NE 250,000 10 10 1* 1000 300 IS NE Sample ID Sample Collection Date Field Parameters Analytical Results Shallow GWA-45 9/30/2015 5.34 8.89 15.6 150 0.5 U 0.5 U 39 0.2 U 15.6 50 UJ 0.0523 3.57 5 U 4 1" --- 2 1.1 480 0.0551 0.958 GWA-45 6/23/2016 5.5 7.9 16.8 165 0.5 U 0.0613 34.2 0.0513 16.8 35.43 0.08 U 3.23 5 U 2.8 3.5 0.52 0.37 0.83 350 0.1 U 0.868 GWA-4S 9/16/2016 5.5 7.5 13.4 135 0.5 U 0.1 U 37.7 0.055 J 13.4 26.4 J 0.08 U 3.42 5 U 3.7 1.1 J+ 0.79 0.15 0.73 248 0.1 U 0.936 GWA-45 12/2/2016 5.8 5.7 11.8 277 0.5 U 0.0431 42.6 0.063 11.8 50 U 0.08 U 3.03 5 U 3.8 1.6 1.1 G.18 1.1 548 0.12 0.899 GWA-4S 3/15/2017 5.9 9.6 13. 198 0.50 U 0.086 J 36.7 0.10 J 13 50.0 U 0.080 U 3.23 5 U 3.7 1.83 0.84 0.16 1.0 J 315 0.1 0.917 GWA-55 6/23/2016 5.8 9.1 13.5 154 0.11 0.21 23.4 0.0221 13.5 50 U 0.08 U 1.47 5 U 1.2 1.5 0.054 0.21 0.283 216 0.12 0.396 GWA-6S 7/17/2015 5.9 2.4 20.6 170 0.79 0.12 J 72 0.153 20.6 50 U 0,08 U 3.36 5 U 3.1 2 --- 0.78 1.9 190 0.4 0.712 GWA-65 9/30/2015 5.87 6.68 19.4 560 0.5 U 0.133 76 0.2 19.4 50 UJ 0.08 U 249 5 U 3.5 1 - - 0.54 1.1 780 0.98 GWA-6S 4/12/2016 5.8 9.3 18.6 156 0.87 0.086 J+ 64.7 0.61 186 50 U 0.08 U 2.93 5 U 2.8 3--3-5 0.35 0.6 76-8 291 1.1 0.668 GWA-65 6/23/2016 5.5 2.7 19.8 9G.5 J 0.5 U G.G66 J 62.4 G.082 J 19.8 50 U 0.08 U 2.82 5 U 2.5 44 S 0.13 0.37 1.7 224 0.15 0.602 GWA-6S 9/16/2016 5.7 9.2 18.3 173 0.5 U 0.0563 66.8 0.1 18.3 50 U 0.08 U 2.86 5 U 2.8 1.5 3+ 0.22 0.11 0.473 267 0.16 0.646 GWA-65 12/6/2016 5.8 7.4 18.7 121 0.261 0.0683 62.4 0.123 18.7 50 U D.08 U 2.57 5 U 2.9 2.5 0.18 0.12 0.44 J 176 0.21 0.579 GWA-65 3/14/2017 5.5 4.8 18.9 83.43 0.50 U 0.18 63.4 0.1 18.9 50.0 U 0.080 U 2.59 5 U 3 3.4 0,173 0.0943 1.4 131 0.15 0.591 GWA-SS 7/21/2015 6 9.6 28.3 1200 0.5 U 0.23 33 0.2 U 28.3 50 U 0.08 U 6.94 5 U 4.3 2.8 - - 0.77 13 i-500 0.38 1.65 GWA-8S 10/1/2015 5.78 9.12 30.8 560 0.5 U 0.5 U 24 0.2 U 30.8 50 U 0.08 U 5.97 5 U 4.6 3.3 --- 0.4 J 4.1 830 0.24 1.5 GWA-85 4/12/2016 5.0 9 30.8 459 0.5 U 0.093 25.8 0.074 J+ 30.8 50 U 0.08 U 6.34 5 U 3.9 2.1 J+ 1.2 0.21 a." J 550 0.22 1.48 GWA-8S 6/22/2016 5.7 9.7 29.7 452 0.5 U 0.061 23.9 0.033 J 29.7 50 U 0.08 U 6.3 5 U 3.6 1.6 0.87 0.1 0.25) 478 0.1 1.41 GWA-SS 12/6/2016 6.1 8.5 32.2 418 0.151 0.11 26.8 0.05 J 32.2 50 U 0.08 U 6.05 5 U 4.4 5.5 1.2 0.42 1.71 517 0.4 1.34 GWA-85 3/14/2017 6.1 8.1 32.1 408 0.50 U 0.24 25.1 0.039 J 32.1 50.0 U 0.080 U 6.13 5 U 4.3 3G-9 0.71 0.27 1.8 561 0.17 1.4 GWA-125 6/1/2016 5.2 1.5 2.93 100 U 0.5 U 0.1 U 66.6 0.0731 2.91 5G U 0.08 U 0.616 5 U 1.5 0.343 --- 4.8 0.423 29.41 0.1 U G.567 GWA-12S 9/16/2016 5.5 2 4.33 100 U 0.5 U 0,0713 40.8 0.031 J+ 4.33 50 U 0.08 U 0.859 5 U 2.1 0.1 J+ 0.076 J+ 5.2 0.323 25.93 0.1 U 0.417 GWA-125 12/6/2016 5.4 1.7 5.2 100 U 0.5 U 0.0591 42.3 G.G21 J 5.2 50 U 0.08 U 0.739 5 U 1.9 0.233 0.36 5.2 13 34.13 0.1 U 0.44 GWA-125 3/14/2017 5.3 0.02 3.33 100 U 0.50 U 0.045 J 48 0,0623 3.33 50.0 U 0.080 U 0.619 5 U 1.6 0.443 0.22 3.7 0.58 50.0 U 0.10 U 0.523 MS-10 9/17/2012 4.97 6.88 3.29 - - -- 1 U 155 --- -- 50 U 1 U 0.29 -- 1.23 0.6693 - - -- 5 U 98.23 1 U 0.471 MS-10 3/19/2013 4.77 6.24 -1-b --- --- I U 134 --- --- 50 U 1 U 0.238 --- 1.25 1 U --- --- 5 U 75.23 1 U 0.412 MS-10 9/12/2013 4.93 4.84 1.53 - - -- 1 U 146 --- -- 50 U 1 U 0.275 -- 1.32 0.959J - - -- 5 U 1141 1 U 0.44 MS-10 3/31/2014 4.94 2.23 20 U --- --- 1 U 150 --- --- 8.833 1 U 0.261 --- 1.31 1.943 --- --- 1.55 J 82.53 0.123 0.462 MS-10 9/22/2014 4.91 3.62 5 U - - -- i U 148 --- -- 50 U 1 U 0.285 --- 1.26 0.7151 - - --- 5 U 1181 1 U 0.454 MS-10 9/14/2015 5.03 9.31 5 U --- --- 0.144) 131 --- --- 4.033 1 U 0.297 --- 1.26 0.9351 --- --- 5 U 382 0.321) 0.433 MS-10 12/21/2015 4.8 8.4 1.21 320 0.5 U 0.16) 150 0.21 1.2 J 50 U 0.08 U 0.246 5 U 1.2 1.2 J+ 0.62 0.76 0.5 J 420 0.33 G.426 MS-10 3/15/2016 4.6 7 33 89.23 0.5 U 0.0561 132 0.14 J+ 33 50 U 0.08 U 0.236 5 U 1.1 0.82 J+ 0.51 0.6 0.22) 107 0.11 0.377 MS-10 6/23/2016 5 4.7 3.23 122 0.5 U 0.074) 129 0.22 3.21 50 U 0.2 0.212 5 U 1 0.99 0.5 0.62 0.43) 139 0.14 0.385 MS-10 9/15/2016 4.8 4.9 2.43 176 0.5 U 0.07) 153 0.18 2.43 50 U 0.08 U 0.258 5 U 1.1 1 J+ 0.81 0.59 0.361+ 193 0.12 0.443 MS-10 12/1/2016 5 8.5 2.11 223 0.5 U 0.08) 130 0.18 2.11 50 U 0.08 U 0.222 5 U G.98 J 0.95 0.73 0.71 0.373 241 0.2,4 G.366 MS-10 3/29/2017 5.09 3.41 3.34 --- 0.106 0.088 119 0.2 --- 3.3 0.101 0.233 --- 1.25 0.864 --- 0.524 1 225 0.293 0.392 MW-4 2/7/2011 6.G3 7.45 --- - - 1 U 1 U 48 --- -- 50 U 1 U --- -- --- 5 U - - --- 5 U 128 1 U --- MW-4 10/5/2011 5.86 5.32 --- --- 1 U 1 U 53 --- --- 50 U 1 U --- --- --- 5 U --- --- 5 U 109 1 U --- MW-4 2/8/2012 5.52 1.57 - - - - 1 U 1 U 49 - - -- 50 U 1 U - - -- - - 5 U - - -- 5 U 70 1 U -- MW-4 6/6/2012 5.73 3.83 --- --- 1 U I U 50 --- --- 50 U 1 U --- --- --- 5 U --- --- 5 U 180 1 u --- MW-4 10/4/2012 5.63 4.38 -- - - 1 U 1 U 46 - - -- 50 U 1 U --- -- - - 5 U - - --- 5 U 38 1 U --- MW-4 2/6/2013 5.89 7.6 21 --- 1 U 1 U 45 --- --- 50 U I U 3.46 --- --- 5 U --- --- 5 U 77 1 U 0.718 MW-4 6/5/2013 5.84 5.92 20 - - 1 U 1 U 48 - - -- 5G U 1 U 3.51 -- - - 5 U - - --- 5 U 164 I U 0.728 MW-4 10/1/2013 5.86 5.16 13 --- 1 U 1 U 46 --- --- 50 U I U 3.44 --- --- 5 U --- --- 5 U 137 1 U 0.707 MW-4 2/6/2014 5.65 2.54 15 - - 1 U 1 U 48 - - -- 50 U 1 U 3.6 --- --- 5 U - - --- 5 66 1 U 0.731 MW-4 10/8/2014 5.73 7.94 16 --- 1 U 1 U 53 --- --- 50 U 1 U 3.31 --- --- 5 U --- --- 5 U 782 1 U 0.822 MW-4 6/8/2015 5.73 0.99 18.3 33 1 U I U 47 1 U 18.3 50 U 1 U 3.49 5 U --- 5 U -- 1 U 5 U 33 1 U 0.725 MVJ-4 2/i0f2Bi-S 5.7 1.9 1S4 450 - -25+i 48 -t4 +5-4 -50U 0:4H 398 3-U 3:9 2i-3 ___ - 6E ii9 0.�8 0-642 MW-4 10/6/2015 5.91 2.72 18.8 175 1.12 1 U 49 1 U 18.8 50 U 1 U 3.46 5 U 1.9 5 U 1 U 5 U 148 1 U 0.761 MW-4 12/11/2015 5.91 1.37 22.4 180 0.5 U 0.5 U 50 0.2 U 22.4 50 U 0.08 U 4.16 5 U 2.000 J- 2.7 2 0.5 U 0,343 250 0.12 0.755 PIW-4 21M2016 5.84 3-k8 4 .5 264 -1-U -1L 51 -1+) Its -0 a MW-4 3/15/2016 5.3 0.5 19.3 50.33 0.5 U 0.0533 41.7 0.1 J+ 19.3 50 U 0.08 U 3.45 5 U 1.7 2 J+ 1.3 J- 0.0283 0.161 78.5 0.1 U 0.69 MW-4 6/1/2016 5.72 0.78 18.6 57 1 U 1 U 48 1 U 18.6 50 U 1 U 3.32 B2 5 U 1.8 5 U --- I U 5 U 49 B2 1 U 0.722 NW-4 6/'22/-20k6 - 4 i4.b 2020 85-U 0.13 71 0:0464 i46 -5&U $:080 3-13 - K 2-1 k< 0-29 0-344 2230 0-32 0-82 MW-4 10/5/2016 5.69 1.93 19.5 62 1 U 1 U 48 1 U 19.5 50 U 1 U 3.65 5 U 1 2 5 U --- 1 U 1 U 76 1 U 0.772 H14-4 _ 5.9 2 8 2&.fi 99i3 4-544 9-019 4 48-3 0.A3S3 206 i&U -R-98-6 4$2 a-U 4-8 2 0.99 0-9523 0-244 i45 b-1-H 0,802 MW-4 2/8/2017 5.76 3.68 21.2 205 1 U 1 U 49 1 U 21.2 5G U 1 U 3.76 5 U 2 5 U -- 1 U 5 U 227 1 U 0.79 P:\Duke Energy Carolinas\Statistics_C AMA\Background Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Marshall\Groundwater\Tables\Table 1 - Marshall SG GW Data_for TM.Asx Page 1 of 4 TABLE 1 BACKGROUND GROUNDWATER RESULTS THROUGH MARCH2O17 MARSHALL STEAM STATION DUKE ENERGY CAROLINAS, LLC, TERRELL, NC Analytical Parameter Manganese Mercury Methane Molybdenum Nickel Nitrate+Nitrite Potassium Selenium Sodium Strontium Sulfate Sulfide Thallium Total Dissolved Solids Total Organic Carbon Vanadium Zinc Radium (Total) Uranium (Total) RepoHing Units ug/L ug/L ug/L ug/L ug/L mg-N/L mg/L ug/L mg/L ug/L mg/L mg/L ug/L mg/L mg/L ug/L ug/L PCi/L mg/L 15A NCAC 02L Standard 50 1 NE NE 100 NE NE 20 NE NE 250,000 NE 0.2- 500,000 NE 0..- 5000 NE NE Sample ID Sample Collection Data y ica Anal [ I Res ul[s Shallow GWA-45 9/30/2015 0.2 U 10 U) 0.68 10.6 1.6 5 U 0.5 U 5.25 40 0.5703 0.10 UJ 0.1 U 53 1 U 0.823 2.93 --- --- GWA-4S 6/23/2016 99. 0.2 U 10 U 0.273 1.9 1.2 5 U 0.5 U 5.16 38.7 0.7603 0.10 U 0.1 U 68 --- 1.1 4.93 -- -- GWA-4S 9/16/2016 41.6 0.2 U 10 U 0.123 0.5 U 1.6 5 U 0.5 U 5.4 38.3 1. U 0.10 U 0.1 U 483, --- 0.64 ]+ 3.53 --- --- GWA-4S 12/2/2016 38.6 0.2 U 10 U 0.143 0.62 1.8 5 U 0.5 U 5.43 40.4 1. U 0.10 U 0.1 U 48 --- 0.74 2.63 -- --- GWA-4S 3/15/2017 15.9 0.20 U 10.0 U 0.183 0.52 1.4 5 U 0.50 U 5.43 39.6 1. U 0.10 U 0.0463 40 1 U 0.95 2.83 --- --- GWA-SS 6/23/2016 16.1 0.2 U 10 U 0.223 1.8 0.099 5 U 0.5 U 4.703 67.6 1.1 0.10 U 0.1 U 45 --- 1.4 34i> -- 0.0005 GWA-6S 7/17/2015 82 0.2 U 1.83 0.343 1 0.120 )- 5 U 0.5 U 5.82 74 0.54) 0.10 U 0.1 U 50 1 U 0.92) 31 --- --- GWA-6S 9/30/2015 77 0.2 U 1.23+ 0.5 U 0.68 0.13 6.94 0.5 U 14.3 64 0.54) 0.10 U 0.1 U 58 1 U 1.2 11 -- --- GWA-6S 4/12/2016 101 0.2 U 30 U 1.4 9.9 0.078 5 U 0.5 U 5.58 73.3 0.8) 0.10 U 0.018) 41 --- 0.6 -5 --- --- GWA-6S 6/23/2016 60 0.2 U 10 U 0.41) 8.9 0.11 5 U 0.5 U 5.37 59.4 0.74) 0.10 U 0.1 U 66 --- 0.65 12.2 -- --- GWA-6S 9/16/2016 30.6 0.2 U 10 U 0.5 U 1.2 0.11 5 U 0.5 U 5.44 59.1 1 U 0.10 U 0.1 U 463+ --- 0.653+ 11.53+ --- --- GWA-65 12/6/2016 16.4 0.2 U 10 U 0.133 1.9 0.12 5 U 0.5 U 4.65 J 58.1 1 U 0.10 U 0.1 U 37 --- 0.68 12.5 -- -- GWA-6S 3/14/2017 13.8 0.20 U 10.0 U 0.193 1.9 0.11 ) 5 U 0.50 U 5.56 60.2 1 U 0.10 U 0.0273 57 1 U 0.603 5.83 --- --- GWA-8S 7/21/2015 +30 0.2 U 1.4) 0.23 1.7 0.02 U 5 U 0.5 U 7.26 190 1.6 0.10 U 0.1 U 72 1 U 3.5 7.13 -- -- GWA-SS 10/1/2015 15 0.2 U 1 l+ 0.173 1.4 0.02 U 5 U 0.5 U 7.62 170 1 U 0.10 U 0.0231 72 1 U 5.5 23 --- --- GWA-SS 4/12/2016 9.2 0.2 U 10 U 0.141 0.72 0.02 U 5 U 0.5 U 7.46 184 4.2 0.10 U 0.025) 64 --- 3.9 14.5 -- -- GWA-8S 6/22/2016 7.4 0.2 U 10 U 0.14) 0.483 0.02 U 5 U 0.5 U 7.19 178 2 0.10 U 0.0163 69 --- 3.3 6.63 --- --- GWA-85 12/6/2016 13.6 0.2 U 10 U 0.191 2.7 0.015) 5 U 0.5 U 6.47 180 1 U 0.10 U 0.1 U 79 --- 5.6 31.8 --- --- GWA-SS 3/14/2017 10 0.20 U 10.0 U 0.40) 5.2 0.02 U 5 U 0.50 U 7.7 185 1 U 0.10 U 0.0203 71 1 U 4.5 6.5 ] --- --- GWA-125 6/1/2016 96.9 0.2 U 10 U 0.5 U 1 0.92 5 U 0.5 U 3.08) 14.2 1.9 0.0001 U 0.046) 25 U --- 0.3 U 4.21 --- 0.0005 GWA-12S 9/16/2016 366 0.2 U 10 U 0.5 U 1.8 0.9 5 U 0.5 U 3.773 12.3 2 0.10 U 0.036 J 19 --- 0.341+ 7.1 J+ 0.331 0.0005 GWA-12S 12/6/2016 -KS 0.2 U 10 U 0.5 U 2.1 0.87 5 U 0.5 U 3.041 11.5 3 0.10 U 0.03 J 29 --- 0.163 9.8) 0.368 0.0005 GWA-12S 3/14/2017 96.7 0.20 U 11.4 0.50 U 1.7 0.79 5 U 0.383 3.06) 11.7 1.8 0.10 U 0.0543 26 1 U 0,113 6.23 0.396 0.0005 MS-10 9/17/2012 30.61 0.05 U -- -- 5 U - - 0.988 1 U 2.2 - - 0.0589) --- - - 24 -- -- 7.31) -- --- MS-10 3/19/2013 25.93 0.05 U --- --- 5 U --- 0.888 1 U 2.09 --- .04473 --- --- 21 --- --- 6.673 --- --- MS-10 9/12/2013 25.21 0.05 U --- --- 0.7771 -- 0.965 0.2921 2.26 --- 0.06531 --- --- 39 --- -- 4.983 -- --- MS-10 3/31/2014 263 0.05 U --- --- 2,753 --- 0.96 1 U 2.38 --- 0,06171 --- --- 193 --- --- 6.953 --- --- MS-10 9/22/2014 27.21 0.05 U --- --- 3.191 - - 0.969 1 U 2.14 -- 0.05913 --- -- 26 --- -- 6.93 J -- --- MS-10 9/14/2015 25.83 0.05 U --- --- 1.453 --- 0.912 1 U 1.97 --- 0.113) --- --- 223 --- --- 5.63 --- --- MS-10 12/21/2015 34 0.2 U 1.5 J+ 0.5 U 1.6 0.95 5 U 0.5 U 5 U 22 1 U 0.10 U 0.1 U 25 U 1 U 1.5 J+ 11 -- --- MS-10 3/15/2016 21.9 0.2 U 1.4 J+ 0.5 U 1.4 0.71 5 U 0.5 U 5 U 20.1 .63 0.10 U 0.1 U 25 U 1 U 0.53 J+ 11.2 --- 0.0005 MS-30 6/23/2016 24.6 0.2 U 10 U 0.5 U 1.4 0.6 5 U 0.5 U 2.093 19.1 0.640) 0.10 U 0.1 U 18 -- 0.77 14.2 -- 0.0005 MS-10 9/15/2016 26.3 0.2 U 10 U 0.5 U 1.6 0.71 5 U 0.5 U 2.083 21.9 1 U 0.10 U 0.0173 25 U --- 0.661+ 7.53 --- 0.0005 MS-10 12/1/2016 25.2 0.13 10 U 0.5 U 1.5 0.73 5 U 0.5 U 1.821 20.4 1 U 0.10 U 0.1 U 25 U --- 0.92 5.51 D.47 0.0005 MS-10 3/29/2017 24.3 0.0334 --- --- 1.19 --- 0.919 0.092 1.83 --- 0.0967 --- 0.024 18 --- 1.02 6.46 --- --- MW-4 2/7/2011 8 0.05 U -- --- 5 U - - --- 1 U --- - - 0.14 --- -- 54 --- --- 5 U -- --- MW-4 10/5/2011 5 0.05 U --- --- 5 U --- --- I U --- --- 0.25 --- --- 63 --- --- 5 U --- --- MW-4 2/8/2012 7 0.05 U -- --- 5 U -- --- 1 U - - -- 0.2 -- -- 63 -- -- 5 U -- -- MW-4 6/6/2012 11 0.05 U --- --- 5 U --- --- 1 U --- --- 0.16 --- --- 55 --- --- 5 U --- --- MW-4 10/4/2012 5 0.05 U -- --- 5 U - - --- 1 U --- - - 0.2 -- -- 46 -- -- 5 U -- -- MW-4 2/6/2013 5 U 0.05 U --- --- 5 U --- 1.92 1 U 3.82 --- 0.12 --- --- 48 --- --- 5 U --- --- MW-4 6/5/2G13 5 U 0.05 U -- --- 5 U -- 2.01 1 U 3.94 -- 0.23 --- -- 46 --- -- 5 U -- -- MW-4 10/1/2013 5 U 0.05 U --- --- 5 U --- 1.99 1 U 3.91 --- 0.13 --- --- 55 --- --- 5 U --- --- MW-4 2/6/2014 5 U 0.05 U -- --- 5 U -- 2.05 1 U 4.23 -- 0.13 -- -- 43 -- -- 5 U -- --- MW-4 30/8/2014 24 0.05 U --- --- 5 U --- 2.12 1 U 4.1 --- 0.12 --- --- 50 --- --- 5 U --- --- MW-4 6/8/2015 5 U 0.05 U --- 1 U 5 U --- 1.97 1 U 4.14 --- 0.11 --- -- 53 --- --- 5 U -- --- MW-9 39 1+{ t.4}F -1-543 -2:54 g-B2-U3 -5-k/ -2iU 44P7 78 -1-U -.4014 MW-4 10/6/2015 6 0.05 U --- 1 U 5 U 2.02 1 U 4.24 93 0.11 --- 0.2 U 53 --- 1.09 5 U -- -- MW-4 12/11/2015 4.73 0.2 U 1.43+ 0.14) 0.66 0.015) 5 U 0.5 U 4,253 100 1 U 0.10 U 0.1 U 41 10.6 1.7 10 U --- --- MW--4 2/4i2016 6 - - -1-4 i-U - 2-44 -1-4 44i 93 0�1k - -0 U 62 - 1-:52 MW-4 3/15/2016 5 U 0.2 U 1.51+ 0.12) 0.5 0.026 5 U 0.5 U 4.321 78.7 0.651 0.10 U 0.1 U 36 1 U 0.96 ]+ 10 U 0.1784 0.0005 MW-4 6/1/2016 5 U 0.05 U -- 1 U 5 U - - 1.96 1 U 4.1 88 0.14 --- 0.2 U 56 --- 0.824 5 U --- -- MWi b{12/2016 37-.5 GAI%4 -1bU bSU 0..6 g.82s ) -5-0 bSU 43243 923 -.70� 04-0 U 4i, U 35-U - 4-.8 6b4 0.444 0.000061 MW-4 10/5/2016 5 U 0.05 U --- 1 U 5 U - - 2.03 1 U 4.29 91 0.13 --- 0.2 U 55 --- 0.801 5 U --- --- MW< 12Jaf2 3,99 b-1U U 0-114 -&.SU 0-:044 -S-U b�U 4s I 956 3-U bi6H Ai-U 49 - i:2 3&U 05697 8�005 MW-4 2/8/2017 5 0.05 U --- 1 U 5 U -- 2.08 1 U 4.39 95 0.12 --- 0.2 U 43 --- 1.47 5 U --- --- WW-4 2f9f2024 i-4F3 ^v8a4 - - i-U 429 - - - Se P:\Duke Energy Carolinas\Statistics_C AMA\Background Determinations for NCDEQ July 7 2017\BW TECH MEMO\Marshall\Groundwater\Tables\Table 1 - Marshall BG GW Data_for TM.Asx Page 2 of 4 Sample ID GWA-4D GWA-4D GWA-4D GWA-4D GWA-4D GWA-4D GWA-5D GWA-5D GWA-5D GWA-5D GWA-5D GWA-6D GWA-6D GWA-6D GWA-6D GWA-6D GWA-6D GWA-8D GWA-8D GWA-8D GWA-8D GWA-8D k MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4D MW-4B MW-4D MW-4D MW-4B MW-4D MW-4D MW-4B MW-4D MW-4D MW-4B MW-4D BG-3BR BG-3BR BG-3BR BG-3BR BG-3BR GWA-12BR GWA-12BR GWA-12BR GWA-12BR i .a -indicates data removed from dataset. --- - Parameter not sampled/analyzed for or value was a non -detected concentration greater than 2L/IMAC. - Indicates data removed/identified as an outlier. • - Interim Maximum Allowable Concentrations (IMACs) of the 15A NCAC 02L Standard, Appendix 1, April, 1, 2013. ' - Hexavalent chromium does not have a NC 2UIMAC standard; therefore, the NC 21 standard for total chromium is relied upon as a surrogate. j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit. I- - Estimated concentration, biased low. j+ - Estimated concentration, biased high. mg - N/L - Micrograms nitrogen per liter mg - N/L - Milligrams nitrogen per liter mg/L - Milligrams per liter NE - Not established NTU - Nephelcmetric turbidity unit pCi/L - picocuries per liter S.U. - Standard Unit U - Results not detected at concentrations which equal the laboratory's method reportinq limit. ug/L - Micrograms per liter TABLE 1 BACKGROUND GROUNDWATER RESULTS THROUGH MARCH 2O17 MARSHALL STEAM STATION DUKE ENERGY CAROLINAS, LLC, TERRELL, NC Chloride Chromium (VI) Chromium Cobalt Copper Iron Lead Magnesium mg/L ug/L ug/L ug/L ug/L ug/L ug/L mg/L 250,000 10 10 1* 1000 300 is NE 4.1 2.1 J+ --- 0.131 60-t 90 0.0811 5.17 4.2 1.8 J+ 0.03 U 0.33 }^ 147 0.45 5.01 3.5 i46 0.054 0.28 3.6 243 0.19 4.4 3.6 0.4 J+ 0.013 0.0611 0.383 60 0.1 U 5.45 3.9 0.4 J 0.013 0.0541 0.5 U 34.51 0.1 U 4.93 3.6 0.381 0.028 J 0.0813 0.241 71.2 0.10 U 5.19 1.9 1.5 --- 0.211 1.9 190 0.13 0.858 1.8 1.41+ --- 0.5 U 0.561 55 0.0461U 1.3 0.63 l+ 0.42 0.0291 0.5 U 50 U 0.1 U 0.778 1.2 2 0.42 0.11 0.69 170 0.093 J 0.776 1.4 1.31 0.8 0.0331 &9 50 U 23 0.808 4 0.85 --- 0.321 0.74 J 67 0.0641 0.84 4 0.961+ 0.0281 2.4 1 166 0.14 2.79 3 1.6 0.16 2.1 1.5 215 0.24 2.32 3.2 0.5 J+ 0.2 1.9 0.82 128 0.12 2.48 3.1 31 0.21 2.6 2 371 0.12 2.34 3.4 6A 0.37 2 1.5 192 0.19 2.42 3.3 1.3 --- 0.291 1.8 J+ 21G 0.0881 1.98 2.4 1.1 J+ 0.28 0.0481 0.323 43.51 0.1 U 1.54 2.3 1.2 0.33 0.18 0.64 173 0.1 U 1.62 3.1 1.7 0.251 0.15 0.623 195 0.1 U 1.68 2.6 42 i-:5 0.i6 0.78 179 0.10 U 1.68 -- 5U -- -- 5U 268 lU --- 5 U -- -- 5U 21 1U -- -- 5 U -- -- 5 U 26 1 U -- -- 5U -- -- 5U 376 lU -- -- 5U -- -- 5U 88 lU --- 5 U -- -- 5U 41 lU --- 5 U -- -- 5U 17 1U 1.28 -- 5U -- -- 5U 18 lU 1.35 -- 5U -- -- 5U 17 lU 1.33 -- 5U -- -- 5U 16 lU 1.3 -- 5U -- -- 5U 25 1U 1.32 -- 5 U -- --- 5 U 37 1 U 1.26 -- 5 U -- --- 5 U 10 U 1 U 1.28 -- 5U -- lU 5U 24 1U 1.37 1.2 1.2 J+ - - 0.5 U 0.383 77 0.0783 1.31 441 - 03-4 2O 2-10 0:0; 39 1-.35 1.4 5 U --- 1 U 5 U 405 1 U 1.41 1.7 1.2 l+ 0.8 0.5 U 0.813 88 0.0653 1.32 %5 3H -1-H 3-U i3 i-U i-.38 1.3 0.62 J+ 0.34 0.1 0.31 110 0.1 U 1.37 1.4 5U lU 5U 17 32 1U 1.37 i-k 0.79 033 &36 8�6 1120 0i9 t.33 1.5 5 U --- 1 U 1 U 28 1 U 1.38 1.3 0.5 0.38 0.0431 0.393 92.9 0.1 U 1.48 1500 si-U i-U 3il 38 i-U i-330 1.2 0.533 0.37 l 0.10 U 0.221 50.0 U 0.10 U 1.37 2.4 7.3 0.03 U 2.1 0.361+ 464 0.1 U 12.9 2.3 4.3 1.7 0.81 1 210 0.1 U 13 2.7 4.1 l+ 3.7 0.29 2 J+ 299 0.1 U 14.3 2.6 4.8 3.31 0.36 5.5 173 0.1 U 13.6 2.5 6.7 3 0.46 3.3 184 0.10 U 12.5 2.7 0.62 --- 0.48 0.4 ] i-530 1 1.77 2.3 0.261+ 0.03 U 1.8 0.21 l 788 0.19 1.93 1.4 0.313 0.18 3.3 0.193 578 0.11 1.64 1.3 0.621 0.053 2.3 0.82 i-220 0.29 1.62 Prepared bv: LWD Checked bv: P:\Duke Energy Carolinas\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Marshall\Groundwater\Tables\Table 1 - Marshall SG GW Data for TM.xlsx Page 3 of 4 TABLE 1 BACKGROUND GROUNDWATER RESULTS THROUGH MARCH 2O17 MARSHALL STEAM STATION DUKE ENERGY CAROLINAS, LLC, TERRELL, NC Analytical personal.] Mang ..... M—.'y Main— 14.1yind.... Nickel Nit,.t. Nit'it. P.t.a.i.on Selenium Sodium Strontium Sulfate Sulfide Thaillu. Di.s.N.d Solid. O'g—ic C-bm, V .. di.m zinc R.di.m (Total) U—i.m (Total) action D 0 oaaoo�®000�a�©e�oee o ®0000�o��o���oe�o 0 o�aooa®o®o�a�©a®oaa Prepared bv: LWD Checked bv: TDP Indicates data removed from dataset. --- - Parameter not sampled/analyzed for or value was a non -detected concentration greater than 21L/IMAC. - Indicates data removed/identified as an outlier. - Interim Maximum Allowable Concentrations (IMACs) of the 15A NCAC 02L Standard, Appendix 1, April, 1, 2013. ' - Hexavalent chromium does not have a NC 2L/IMAC standard; therefore, the NC 21 standard for total chromium is relied upon as a surrogate. j - Estimated concentration above the adjusted method detection limit and below the adjusted reporting limit. 1- - Estimated concentration, biased low. j+ - Estimated concentration, biased high. mg - N/L - Micrograms nitrogen per liter mg - N/L - Milligrams nitrogen per liter mg/L - Milligrams per liter NE - Not established NTU - Nephelometric turbidity unit pCi/L - picocuries per liter S.U. - Standard Unit U - Results not detected at concentrations which equal the laboratory's method reporting limit. ug/L - Micrograms per liter P:\Duke Energy Carolinas\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\13TV TECH MEMO\Marshall\Groundwater\Tables\Table 1 - Marshall EG GW Data for TM.xlsx Page 4 of 4 TABLE 2 GROUNDWATER BACKGROUND THRESHOLD VALUES MARSHALL STEAM STATION DUKE ENERGY CAROLINAS, LLC, TERRELL, NC Parameter Reporting Unit NCAC 02L Standard Background Threshold Values Shallow Deep Bedrock pH* S.U. 6.5-8.5 4.8 - 6.1 5.8 - 7.9 5.9 - 7.1 Alkalinity mg/L NE 29.7 238 108 Aluminum pg/L NE 926 190 463 Antimony pg/L 1° 1 0.5 1 Arsenic pg/L 10 0.219 1.5 1 Barium pg/L 700 148 45.5 66.9 Beryllium pg/L 4° 0.374 0.0759 1 Bicarbonate mg/L NE 30.8 238 108 Boron pg/L 700 50 50 50 Cadmium pg/L 2 0.08 0.08 1 Calcium mg/L NE 6.05 88 13.7 Carbonate mg/L NE 5 5 5 Chloride mg/L 250 4.3 5.19 2.7 Chromium (VI) 1 pg/L 10 1.74 1.48 4.82 Chromium pg/L 10 4.82 2.55 5 Cobalt pg/L 1° 3.7 2.4 3.80 Copper pg/L 1000 3.13 3.78 5 Iron pg/L 300 818 337 676 Lead pg/L 15 0.738 0.348 1 Magnesium mg/L NE 1.52 8.72 13.6 Manganese pg/L 50 82 187 310 Mercury pg/L 1 0.05 0.2 0.05 Methane pg/L NE 10 10 16.4 Molybdenum pg/L NE 0.684 9 4.26 Nickel pg/L 100 5.94 7.33 5 Nitrate + Nitrite mg-N/L NE 1.6 0.895 0.381 Potassium mg/L NE 5 4.45 8.19 Selenium pg/L 20 0.5 0.5 1 Sodium mg/L NE 9.75 39.9 14 Strontium pg/L NE 197 548 195 Sulfate mg/L 250 1.9 50.3 14.4 Sulfide mg/L NE 0.1 0.1 0.1 TDS mg/L 500 79.8 257 177 Thallium pg/L 0.2° 0.2 0.1 0.2 TOC mg/L NE 1 4t It Vanadium pg/L 0.3° 6.88 4.37 22.9 Zinc pg/L 1000 15.9 31.1 10 Radium (Total) pCi/L NE 0.47t NA 1.9 Uranium (Total) pg/mL NE 0.0005 NA 0.0005 Prepared by: JHG Checked by: MCM Notes: * - Upper and lower tolerance limits calculated for parameter A - Interim Maximum Allowable Concentrations (IMACs) of 15A NCAC .02L Standard, Appendix 1, April 1, 2013 pg/L - micrograms per liter pg/mL - micrograms per milliliter t - Provisional; dataset contains less than 10 valid samples - Hexavalent chromium does not have a NC 2t11MAC standard; therefore, the NC 2L standard for total chromium is relied upon as a surrogate. mg - N/L - Milligrams nitrogen per liter mg/L - milligrams per liter NA - Not available; dataset contains zero valid samples NE - Not Established pCi/L - picocuries per liter Radium (Total) - Radium-226 and Radium-228 combined S.U. - Standard Unit TDS - Total Dissolved Solids P:\Duke Energy Carolinas\Statistics_CAMA\Background Determinations for NCDEQ July 7 2017\BTV TECH MEMO\Marshall\Groundwater\Tables\ TABLE 2 - Marshall GW BG Threshold Values.xlsx Page 1 of 1