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Home My WebLink About_Revised_Allen CBE - Appendix A 1.29.20_20200129ESTIMATED VOLUME OF CCR MATERIAL IN IMPOUNDMENT AECOM Job Description Duke Energy —Allen Closure Estimated Volume of CCR Material in Impoundment Project No. 60572629 Computed by ANR Sheet 1 of 2 Date 9/27/19 Checked by JDM Date 1/20/20 The purpose of these calculations is to estimate the quantity of the coal combustion residual (CCR) material located within the Ash Basin at the Duke Energy Allen Steam Station (Allen), located in Gaston County, North Carolina. These calculations have been developed independent of past calculations/estimates prepared by others, and the actual volume of CCR within the Ash Basin will vary from that presented previously. This variability is primarily due to the differences in data sources/references used in the calculations. These volume estimates will be refined if more accurate data is collected throughout the design process. APPROACH CCR Quantity within the Ash Basin To illustrate the depth of impounded ash, the approximate pre -development topography (see Figure A-1), which is based on the Duke Energy drawing No. A3350-113 titled "Ash Storage Basin, General Plan, As Built Topography", dated 11/11/1975, was compared to existing topography, which is based on topographic survey performed in February 2015, and bathymetric contours from AMEC Foster Wheeler's Waste Strategy Analysis report, dated April 2015. This comparison was performed using AutoCAD Civil 3D version 2016 (AutoCAD). The quantity of CCR material within the AAB and RAB was subsequently calculated, using AutoCAD Civil 3D, as the volume differential between the pre -development topographic contours and the existing topographic contours (see Figure A-2) within the Ash Basin Waste Boundary, except in the RAB landfill and DORS 1 and DORS 2. In these areas, pre - development topography was compared to base grades underneath the fill areas. This comparison is shown in Figure A-3. The overall estimated volume of CCR material within the AAB and RAB was calculated using AutoCAD as discussed above; however, the data was supplemented with information from Duke's CCR Inventory Data (dated 4/30/19) and with scaled tonnage data through 7/31/19. The quantity of CCR material within the RAB and AAB waste boundaries was calculated to be approximately 16,327,200 cubic yards (CY) or 19,364,500 tons. This includes the unlined Distribution of Residual Solids (DORS) facilities that were constructed over the west portion of the RAB. A break -down of these quantities is presented in the attached Tables 1, 2A, 213 and 2C. CONCLUSION Based on the calculations described above, the total quantity of CCR material within the Ash Basin at Allen is estimated to be approximately 16,327,200 CY, or 19,364,500 tons. AECOM Job Duke Energy —Allen Closure Project No. 60572629 Sheet 2 of 2 Description Estimated Volume of CCR Material Computed by ANR Date 9/27/19 in Impoundment Checked by JDM Date 1/20/20 III. ATTACHMENTS Attachment A: Figures - Figure A-1— Pre -Development Topography - Figure A-2 — Existing Topography - Figure A-3 — In -Place CCR Material Isopach Map Attachment B: Tables - Table 1— Estimated Volume of CCR Material in Impoundment Subject to Closure Plan - Table 2A — Inventory of CCR for North Carolina Coal Ash Impoundments - Table 213 — Inventory of CCR for Other North Carolina CCR Facilities - Table 2C—Additional Breakdown of CCR Quantities ATTACHMENT A Figures ALLEN STEAM STATION REV. INCHES TENTHS 1 30 1 PLANT ALLEN RD -------- - __---'' --''\\ COT I I I ACTIVE ASH BASIN 575 RETIRED ASH BASIN DIKE tiOonl C-0 LAKE WYLIE/ CATAWBA RIVER LAKE WYLIE/ CATAWBA RIVER 0 300 600 900 GRAPHIC SCALE (IN FEET) LEGEND: HISTORIC MAJOR CONTOUR (25 FOOT) HISTORIC MINOR CONTOUR (5 FOOT) LIMITS OF IMPOUNDED ASH NOTES 1) LIMITS OF IMPOUNDED ASH ARE APPROXIMATE. 2) (5 FT) CONTOURS WERE DIGITIZED FROM HISTORICAL TOPO BY AMEC AS PART OF THE WASTE STRATEGY ANALYSIS REPORT DATED APRIL 2015. (FIGURE 2.2). 3) A DATUM SHIFT OF -0.75 FT WAS APPLIED TO CONVERT ELEVATIONS FROM NCVD29 TO NAVD88. REFERENCES 1) DRAWING NO. A3350-1 B ENTITLED "ASH STORAGE BASIN, GENERAL PLAN, AS BUILT TOPOGRAPHY", PREPARED BY DUKE POWER COMPANY, DATED 11/11/75 TITLE PRE -DEVELOPMENT TOPOGRAPHY RETIRED AND ACTIVE ASH BASINS AAECOM -\LLLIN 5 1 rzrlivi 5 1 A 1 lUIN 4v18 CLOSURE PLAN UPDATES GASTON COUNTY, NORTH CAROLI N.C. ENGINEERING LICENSE NO. FOR F-0342 ISSUED r- REVIEW SEAL SCALE: DES: DUKE DWG TYPE :. DWG DFTR : ENEJOB NO: CHKD: RGY® DATE: ENGR: FILENAME: Figure A-l.dW APPD: DWG SIZE DRAWING NO. REVISION ANSID 22.0"x34.0" FIGURE - A-1 V 9 10 1 1 REV. Au I /rill t\ I / / 1 - \\ 119� 311a— 3 �3 _ 3 / 3Ne— 3 3 3HB� 3HB� �}— �- M&— 3�1� 311�� - �._ \ -/ �3XC--�/ 3 311�— 3Fi� 311�� __ • / li \ i i - -N --- _i PLANT ALLEN R \♦ 1 , I I ` j`��/ III / �\ /�{// i 3\\ \, ; — ASH i 'W iil�;v.--k,,� 3V�-�- 31i0-- 311�- 3i1B---i- 311�-�` -{{' / , \ __\ I , III ��\' °� STORAGE 1fill, 1111�1 - \ /_�_ INACTIVE ! m m I i�li� 1 \ /^ %'%I' / / /` W m 1 r 1 I 1! IIIII 1 ALLEN STEAM f E/ STATION •\ \ ('i�. \ �- _ j `r ��i! jam' /��/ 7lf l —1 \ \\I •"11 j``\.�-\= �-'_\ \ \J r� SI, COAL YARD I I / \\v / rr 1 1 . /// t / _ ASH 1 1 i i Iilii i �� \� — — — `mot—$,' �I %jf BASIN ,1 _RETIRED ASH BASIN DIKE \ o I 1 I off�p 1• _ W �1 //l 0 6, r I \ i 1 ,/ I t I / 1 , ,n / / % 1 11 1 w`r♦ \ \ 6� I W m[tw / 1 I 1 ''� t't/� 1 c�-�" /' CO cs cNo /- coco cu co`I� F \ // f/ `� �� M i I W � .� � 1 / I IIIII , 1 II // / ��_ \Nbyp �� r.. , 630\ ty625 I �%- N 01 ASH F I L L 2 j1111 I j / 635 c 6��= t =f '� \ �\ ASH FILL 1 \-------\\ \ i \ , \\ ` _ — — 625 � \-\\ I 1��Iill � 11, l r, � _ —'—_� _ I r--___. _- i'-------- ' j % �- , +\, 1111 I IIIII 1 1 11 I ,11 I Mill l 1 �___ J-J +-`�� — _ _ — 650 1 L I, 1, 1 (I I 1 1 I I i 1 I r•---------_- _r ' ASH I► 11 ''/'I w I RETIRED ASH BASIN /^\ .1 ,,i ICJ 1l01, 1, I 1, �nllj 1 ,II STORAGE IoI II�,II 'm!I ; I,�°III•, 1'I i f�1f ii;i; I ' I l RETIRED ASH BASIN '', I I „I W I I 'll� ASH LANDFILL I / 1 \ I 1 1 Ili 11 I I INACTIVE , 11111 11 I I lII �\ ''' ' W' IIIII 111 i Ill, 111i1 PERMIT NO. 3612 �I r-\ ` `\\`\ : '\ ��_ / �--. ASH ,11 ► m ,1 a I I� I I I 1�1, Illll 1 I l ` \ \ ..\ \ \ .r t l,1 I II I l l l „ I I I, I I I I I BASIN IIII 11 — — — _ 1 I Ill\lilt I'll Z� I I I I I III II (I 1 %'/l ♦� - \ '\ roIIIII 1p I (I ti�� -_- _ --�Jll l \� �o �675 --__—_ �\\ \``----- -�\ ` :� /I ' 11 I I \\ /-^\ \�__'-` ✓'�\ \ \� \-----'---\ \\ /_--/ �- 1 1< 645 620 ---- --- __� — — /- 1 I- 1, \\\ \ \ \ �� -i/ \\------tz _ /- ---/ 1 ' I `\\ \ \ / r— �\ I (� \\\ \ , '� / i',//..� 1 t �, ____''— _________________-620 = — ^ -w /, / `— ' — �ss`5--� \ \ / ^---------- 1 1� �%J i ` s `- � � _= DIKE ----- ��'� Il�li Il1ll / ' \ \ , / I 640 \ \ �r /, \ 1__---- __= NORTH �- 19 , l 1 I I I 635 r i 1 i i I I \` /m � CELL 2 c CELL 3 -- CELL 1 r 630 l \ - �r--••-_-� i / W � / ,orI /`-\�•\l coI II'l.-Illp It l If 16 m 1 N I I o 11I tY� $0� { �� ',,, �/ + 6'ca ,I co II to III \\\ _i------r-__\ W 1 61 L I/! % 6w 's I s� I , ��I•I ��Il�jj� It --- _�` W 1'♦ tJ 11 C 30`�\ Lo r _ r� 1�r /� IIIII II IIIII �n I i I \ t; i ,1?to L0 I Ili ll� 11 �1 \ 1 \ W m h / ' �- ` ♦ \ � \ �` 11 s60 / , •�.-sia.��i��--•_.i�a�+.ii i 1 1 ACTIVE ASH BASIN I � / 10 �/ mho ' /!' It ` co / � J M. 1 i - _ / / \ _ / / \ \\ \ \ \\ \\ \`\''' J Ile A le If / i 1'J / ` i 1 .010 \ \ \ t 1 \ i IIcNo It It ex J� i _� 1 ♦\ I I�, I �I�II�� III �.�r Y �. t� Il Milli Ijll ' I• Ij1ljl j11\ �� oit1\ 63p^h Q I In o - Lu I II1 , ♦ N ,I II s C ��POLISHING I1l'jt �� POND IIII \\\\ n , IlJill 04 ll I co Lop 00, \ ♦` 626 .00 f000 / / // If 01 jll I �l I I I1 II I II 1 II 1 II 1 I I 1 II I I 1 1 1 1! 0 300 600 900 GRAPHIC SCALE (IN FEET) LEGEND: LAKE WYLIE/ CATAWBA EXISTING MAJOR CONTOUR (25 FOOT) RIVER EXISTING MINOR CONTOUR (5 FOOT) LIMITS OF IMPOUNDED ASH BATHYMETRIC MAJOR CONTOUR (25 FOOT) BATHYMETRIC MINOR CONTOUR (5 FOOT) LIMITS OF BATHYMETRIC SURVEY EXISTING TRANSMISSION LINES ,J�, pd ® TRANSMISSION TOWERS / POLES NOTES 1) LIMITS OF IMPOUNDED ASH ARE APPROXIMATE. 2) AERIAL TOPOGRAPHIC SURVEY WAS PERFORMED BY WSP IN FEBRUARY 2015. 3) BASIS OF BEARINGS: NC GRID NAD83. 4) ELEVATIONS ARE BASED ON NAVD88. 5) UNDERGROUND UTILITIES ARE NOT SHOWN IN THIS FIGURE. 6) VOLUME OF FREE WATER, WITHIN THE LIMITS OF BATHYMETRIC SURVEY SHOWN, IS APPROXIMATELY 92 MILLION GALLONS. 7) THE VOLUME OF FREE WATER WAS OBTAINED BY COMPARING THE EXISTING TOPOGRAPHY SURVEY AND THE BATHYMETRY SURVEY SURFACES, IN AUTOCAD CIVIL 3D. REFERENCES 1) BATHYMETRIC SURVEY SHOWN WAS OBTAINED FROM AMEC'S WASTE STRATEGY ANALYSIS REPORT DATED APRIL 2015. TITLE EXISTING TOPOGRAPHY RETIRED AND ACTIVE ASH BASINS P"=com -\LLLIN 5 I LAM 5 I A I WIN 4v18 CLOSURE PLAN UPDATES GASTON COUNTY, NORTH CAROLINA LAKE WYLIE/ CATAWBA N.C. ENGINEERING LICENSE NO. FOR F-0342 r r w RIVER ISSUE REVIEW SEAL SCALE: DES: UKE DWG TYPE:.DWG DFTR: JOB NO: CHKD: ENERGY® [DATE. ENGR: FILENAME: Figure A-2.dwg APPD: DWG SIZE DRAWING NO. REVISION ANSID 22.0"x34.0" FIGURE - A-2 V INCHES TENTHS 10 20 30 10 1 REV. C ALLEN STEAM n I� la \ \� �� 1 l \ \ -• V STATION �\ d ILI- —/ �—'. -- ' ( ► '\ \tip Nz PLANT ALLEN RD 0 300 600 900 I✓ GRAPHIC SCALE(IN FEET) 1 II �I 2S\� Lo RETIRED ASH BASIN DIKE LEGEND: co I - ---_ �� EXISTING MAJOR CONTOUR (25 FOOT) �✓'\ _- `— �1 / l� I I I I I �^ 1 I LAKE WYLIE/ CATAWBA RIVER EXISTING MINOR CONTOUR (5 FOOT) �I l II L� U� I IIII ✓� ��\�__� tl IIII I LIMITS OF IMPOUNDED ASH if H BASIN RETIRED AS — _ — -_ I I III II I IMPOUNDED ASH , , �� I I I NUMBER DEPTH (FT.) COLOR l -� I I III I, I II II I II I ,I�I� IIII I I I �I II Ill II II III I ✓I II II II III 1 10.00 I� I I I � o � I I � III I � 2 20.00 III I I N I II I 3 30.00 1 � I I �� I � I �� III I I _ _ __�� — .� ooJ I � I I 4 40.00 �l �- \�I��f�ll IIIII { II ��{- _ ----_— _--� Iillll / I \� \ II ►��/� I — _ — _ _ _ — _ I I 5 50.00 NOTES i -- \ \ \ _ — J �� I I✓ _ _ _ ,� �_ _ II I) 6 60.00 1) LIMITS OF IMPOUNDED ASH ARE APPROXIMATE. 7 70.00 2) IMPOUNDED ASH VOLUME WAS CALCULATED USING 8 80.00 AUTOCAD CIVIL 3D SOFTWARE. IKE NORTH D 9 90.00 3) SURFACES SHOWN ON FIGURES 01 AND 02 (EXISTING II 10 100.00 TOPOGRAPHY AND PRE -DEVELOPMENT TOPOGRAPHY RESPECTIVELY) WERE COMPARED TO GET THE 11 110.00 VOLUME AND THICKNESS OF IMPOUNDED ASH. 12 120.00 I l r II / III II II III � II0Is , r I II I� �. � -65 i — ; IIII\ ACTIVE ASH BASIN � fr �IIII I�� II II Q � � �. j1 1 I II III III TITLE IMPOUNDED ASH THICKNESS III I o r�t ll i RETIRED AND ACTIVE ASH BASINS ALLEN STEAM STATION 2018 CLOSURE PLAN UPDATES GASTON COUNTY, NORTH CAROLINA LAKE WYLIE/ CATAWBA FOR ISSUED FOR REVIEW — — \\\ \ �� \\ 11 RIVER SCALE: DES: ANR DWG TYPE:. DWG DFTR: ANR JOB NO: 60572629 CHKD: JDM DATE: 1-30-19 ENGR: JDM FILENAME: Figure A3.dw APPD: JDM DWG SIZE DRAWING NO. REVISION ANSI D 22.0"x34.0" FIGURE - A3 C INCHES 1 2 3 TENTHS 10 20 30 1 5 6 ; 8 1 10 ATTACHMENT B Tables Table 1: Estimated Volume of CCR Material in Impoundment Subject to Closure Plan Allen Station CCR Inventory CCR unit tons CY Retired Ash Basin (RAB)1 8,884,500 7,593,900 - RAB Area Outside RAB LF Footprint 4,760,300 3,966,917 - RAB Ash under landfill including subgrade 1,992,000 1,660,000 - RAB Ash above liner in landfill 2 1,141,000 1,141,000 - DORS 1 428,400 357,000 - DORS 2 562,800 469,000 Active Ash Basin (AAB) 3 10,480,000 8,733,300 GRAND TOTAL 19,364,500 16,327,200 1 Future ash production to be placed within the lined RAB Landfill beyond 7/31/19 is excluded. 2 CCR material tonnage provided is based on CCR Inventory Data provided by Duke as of 7/31/19. A conversion factor of 1.2 tons/cy of CCR was assumed, with the exception of ash contained within the RAB Landfill above the liner, in which case a factor of 1.0 tons/cy was used. 3 Sluicing of CCRs to the AAB ceased on February 9, 2019. Table 213: Inventory of CCR for Other North Carolina CCR Facilities CCR Inventory Data Valid As of July 31st, 2019 State Site Facility Type Facility Name Current CCR Inventory (tons) NC Allen Landfill RAB Landfill (includes CCR above liner) 1,141,000 NC Buck Dry Ash Stack Additional Primary Basin Dry Stack 235,000 NC Cliffside Dry Ash Stack Ash Storage Area 1 204,000 NC Mayo Pond FGD Settling Pond 29,232 NC Mayo Pond FGD Forward Flush Pond 2,664 NC Roxboro Landfill East Ash Basin Landfill (includes Subgrade Fill, Unlined Monofill, and Lined Monofill) 14,455,000 Table 2C: Additional Breakdown of CCR Quantities CCR Inventory Data Valid As of July 31st, 2019 State Site Facility Type Facility Name Current CCR Inventory (tons) NC Allen Pond Retired Ash Basin ash outside of landfill footprint (excludes DORS No. 1 and DORS No. 2) 4,760,300 NC Allen Pond Retired Ash Basin ash under the landfill footprint (excludes 600,000 tons of Subgrade Fill) 11392,000 NC Allen Fill Landfill Subgrade Fill (below liner) 600,000 NC Allen Fill DORS No. 1 (within RAB footprint) 562,800 NC Allen Fill DORS No. 2 (within RAB footprint) 428,400 NC Roxboro Pond East Ash Basin ash outside landfill footprint (excludes Eastern Extension Impoundment) 3,770,400 NC Roxboro Pond East Ash Basin impoundment ash under the landfill footprint 3,186,000 NC Roxboro Pond East Ash Basin Eastern Extension Impoundment 117,500 NC Roxboro Pond West Ash Basin Southern Extension Impoundment 241,000 Sheet 2 of 2