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Home My WebLink AboutCCB0031_1804_DukeMarshallSF_NorthStabilityFeature_Phase1Dewatering_observationwellinstall_Request_FID1810470_20230707(' DUKE ENERGY-. July 7, 2023 North Carolina Department of Environmental Quality Division of Waste Management Solid Waste Section 2090 U.S. Highway 70 Swannanoa, NC 28778 Attn: Ms. Sarah Moutos (submitted electronically) Re: North Stability Feature — Phase I Dewatering and Observation Well Install Request Permit Numbers: Structural Fill (CCB0031) Marshall Steam Station Terrell, North Carolina 28682 Dear Ms. Moutos, 526 South Church St. Charlotte, NC 28202 Mailing Address P.O. Box 1006 Mail Code EC 13K. Charlotte, NC 28201-1006 Duke Energy Carolinas, LLC (Duke Energy) requests approval to install dewatering and observation wells within the vicinity of the Structural Fill (CCB0031) at the Marshall Steam Station in Catawba County, North Carolina. Dewatering and excavation to construct the stability features will be conducted in phases. A combination of deep dewatering wells and shallow well points will be installed as a system to lower the water table to support initial excavation and construction of the Structural Fill northern stability feature. Observation wells will be installed to monitor water levels during each phase of dewatering and excavation. The first phase of dewatering and observation wells to be installed with this request include: • Forty (40) deep dewatering wells, • Ninety-six (96) shallow dewatering well points, • Six (6) deep observation wells, and • Two (2) shallow observation wells. Attached to this letter is a plan view figure and cross section depicting the approximate location of each dewatering and observation well. A well construction summary table is included on the attached plan view figure, and well schematics for each type of well are included in the attached details. All wells will be installed and screened in ash. The dewatering wells are expected to be operational throughout the duration of the northern stability feature construction, estimated to be at least 6 months from the start of dewatering. Water extracted with the system will be routed within the ash basin for treatment at the onsite water treatment system prior to discharge through an NPDES outfall. As necessary, dewatering and observation wells may be preserved to continue dewatering during installation of the geosynthetic cap over the stability feature. Those wells would be amended with a vertical penetration boot similar to those detailed in the Stability Feature Engineering Design Report (Rev 2; AECOM, 2023) drawing MAR _C999.003.044. Wells will be abandoned, and geomembrane patched as necessary, at each location once the dewatering system is decommissioned. Note, subsequent requests will be submitted as the need to build out the dewatering system develops to support the following phases of construction for the stability feature. www.duke-energy.com Page 1 of 2 If you have any questions or need additional information regarding this request, please contact me at Ashley.Healy(a�duke-enerqv.com or (717) 982-0986. Respectfully submitted, j4VAi Ashley Healy, P.G. Environmental Services Attachments: Structural Fill North Stability Feature Plan View and Cross Section — Phase I Dewatering Drawings - KII-101, KII-102, KII-08, and KII-109 (Keller, 2023) cc (via e-mail): Claire Osborn, NCDEQ Jordan Russ, NCDEQ Ed Mussler, NCDEQ Sherri Stanley, NCDEQ Scott Saunders, Duke Energy Chris Varner, Duke Energy Dan Zakary, Duke Energy Tyler Hardin, Duke Energy Kim Witt, Duke Energy Ed Sullivan, Duke Energy www.duke-energy.com Page 2 of 2 Stn,rt,,,al Fill CrRMAi Mn.th Stahili V Feature Prnnated Oewaterina Well Cnnitrurtinn Detab is Ap;NI Ground Proposed Dewatering Surface line Number Approx_ Well Approx. Well Well Screen well screen 'WellScreen Well Litie Station Length Depth Spain' Depth Rattle Depth SeQuenor Method rctevatiw, 'h) of Devices Ih. I(ft. on renters) length (IT) (h.Ili h. rnsl. DevateWL4t1ng I 2t55 833 500 26 455 19-5 20 25.5 to 45S shhaPoorre D ing Ash Pore DW-2 Wd Wells 3440 834 445 14 465 325 20 25.5 to 465 Ash Parents WPT-] Wellpoi 5.05 927 450 4s 30 ?0 10 20to30 Water Ash Pore WPT-2 WNlpaints S-W 926 520 51 30 ?0 10 20 to 30 Water 1 Deep DOW-1 tc OW-1DOW- Observation 3.00 834 nfz 3 45.5 n1i 20 2S.S to 4S5 Ash Pore Water wells Deep DOw•4 tc Observation 3.74 934 a/a 3 4S.5 Na 20 25.5ta4SS Ash Pore DOWN Wells w ater Shallow SOW-1 & Obsembon 4485 826 m1a 2 30 44 20 20 to Ash Pore SOW-2 wells Z1Ill�� . 0 1. DISCHARGE FROM THE DEWATERING SYSTEMS WILL B KEPT WITHIN THE ASH BASIN AND PUMPED THROUGH THE ti TREATMENT SYST EM PRIOR TO DISCHARGE THROUGH NPDES ;/ OUTFALL 002.E P 2. EXISTING STORM WATER PIPES TO BE EXPOSED PRIOR TO WELL DRILLING. 3. ALL WELLS WILL BE INSTALLED WITHIN THE ASH BOUNDARY. NI Q / b EXISTING STORMWATER PIPES J] (SEE NOT 2) LEGEND • DEEP DEWATERING WELL • WELLPOINT DRILLED DEEP OBSERVATION WELL HAND JETTED SHALLOW OBSERVATION WELL DW HEADER PIPING WPT VACUUM HEADER PIPING DISCHARGE PIPING EXISTING MAJOR TOPOGRAPHIC CONTOUR EXISTING MINOR TOPOGRAPHIC CONTOUR _ ASH EASIN BOUNDARY (APPROXIMATE) - _ - ILF PHASE LIMIT - (APPROXIMATE) EXISTING SITE FEATURE (APPROXIMATE) A 11 t;►t r, It I it I LIVE STA. 2+55 j t I APPROX. EL+833 Will" t 1' , Water 1 t 1 �! 1 t `1J l+1 'L 1 41 tr ,1 it l I Jill I10'1+`t,1li=tl` �t ` t DW UNE 1 � 1 p , STA. 3+40 .(✓j1 APPROX. EL-+834 r II 1 t'li 1' 11 t 111, t, t 1 � 1 1 = 1 it;•l�;lt,��tl1lt�tl� 1 r--- r f '' i�,tlttl,is 11��t1 IN I. OVERALL SITE PLAN SCALE: 1' = 1CO' a 0 M Q, e a KELLE a 100 STICKLE AVENUE ROCKAWAY, NJ 07866 973-627-2100 WNW.KELLER-NA.COM Q ` ,y.e., A C L KNA O O I Z ~~ z > ca OT-�--, ', ♦"`tom ("'1 � LLI � � U o N LL ..ti3►�' g�l-tt x� ` ,•°° `� t LLI m L TOTAL DISCHARGE = 300ft (SYST'EW TO SYSTEM) + 2,000ft = TOTAL 2,300ft TO FIMIZE PFASES AREA/EASIN (SEE NOTE 1) WPT-2 LINE---�_�--------- "' STA 5+80 --- ��ti "APPROX. EL.+826 ---------------- I" 1 �; Engineer of Record: 1 _WPT-1 LINE STA. 5+05 r �`�♦ \, t 1 1 APPROX. EL+827 ` ♦� \ �! ;�+� ` ( �: " , �r �♦ \� \\r 1HIS ITEM FIAS BEEN ELECTRONICALLY \ ( \ \ r \ SIGNEC AND SEALED USING A DIGITAL ` I rr ��`~\� �� ♦♦\\� \ SIGNATURE. /f / J L \ \� I PRINTED COPIES OF THIS DOCUMENT ( � / / t* ih ` \ : \ ,yt + ' \�: ARE NCT CONSIDERED SIGNED AND + j r♦ \ \ 11 ti ; ; t< SEALED AND THE SIGNATURE MUST BE VERIFIED ON ANY ELECTRONIC COPIES. r l i q-� ti •� �� ♦ ! i 1� t� �� Drawn by: Checked by: jIll I All Project Number: Date: r rN �� -= - � boo• 17451031 04/24/2023 0 100, 200' Sheel No. IF SHEET IS LESS THAN f 7' X 11 • SCALE A[:LLq*CLY K11mill 01 Rio KQ 400 an aw -040 a.a aaa aaa am 7W 780 770 Q-W I+w EXCAVATED STACKED ASH I STRUCTURAL FILL (PV) NORTH,- PHASE II CROSS SEC1lON A —A T COMPLETEE IN MAY 2023 r o: •" T� a0tl � 4 -..E. AI N E�0 r- -1 N, pM1 ST MYYATER BENCH 1 4w 1 2 ��k aaa 1 MEASU D EXISTING ex pQMI-1 D4M-4 I sOhl-2 HISTORICAL DE! )UP-2 DUM-5 EST TED BOTOM OF kSH W ® — SECTION A —A PHASE II HORIZONTAL SCALE: 1" = 100' VERTICAL SCALE: 1" = 50' LEGEND WON W 4H DEW MN "Mm ow TWO Inc ORIo- aC a 100STICKLE AVENUE ROCKAWAY, NJ 07866 973-627-2100 W1NW_KELLER-NA_COM a 0 0 ■ I6 ' E L M 0 LLI OCl) � (3) °� z U W m LL LL _m m }i C�7? M V � Engineer of Record TH15 ITEM HAS BEEN ELECTRONICALLY SIGTQFD AND SEALED uSING A DIGITAL $IGNATURE. PRINTED COPIES OF THIS DOCUMENT ARE NCT CONSIDERED SIGNEDAND $EALEE AND THE SIGnATURE MUST BE VERIFIED ON ANY ELECTRONIC COPIES. Drawn by: Checked by: I YUC>cAL SCNS- r - 5V RRC AHC o so 1W Project Number; Date iiiia 17451031 04I241202't HORI2OMUL SCALE I • — 1 W Sheei No - 1r _ KIM 02 IF SHEET rS LESS TFUNX 11' SCALE ACCORO114CLY 1.5' 0 VALVE INSTALL GRADE WI T-1 +827 1.5" 0 SWING HOSE WPT-2 +826 FERNCO COUPLINGS JP TO OR THE WHICF ENCQII INSTALL GRADE (VARIES) TEMPORARY SCH40 PVC VACUUM HEADER .,I Al ' 2" 0 SCH40 PVC WELL CASING 2"0 SCH40 PVC NELL SCREEN 3.020" SLOT SIZE #1A FILTER PACK (DSI) .25" 0 SCH40 PVC )RAWDOWN TUBE `VC CAP I MATE r"ni F TYPICAL WFLLPOINT DETAIL SCALE: N/A UP TO 3D' BG5 OR TO PRACTICAL R15EFUSAL WHICHEVER EINqbUNTERED FIRST rnD 2" 0 SCH40 PVC WELL SCREEN 0.020" SLOT 512E #1A FILTER PACK {DSI) APPROXIMATE 6'0 BOREHOLE TYPICAL SHALLOW OBSERVATION WELL DETAIL SCALE: N/A 100 STICKLE AVENUE ROCKAWAY, VJ D7866 975-627-2100 WVVW.KELLER-NA.COM J 0 4 od Z z w Vol c DJ ■#5 2 a LIJ C Cam] L1J L 43 0 Z 0 #' CZ z U) LL LL ZZ LL 4f co IZ m Q I Engireer of Record THIS ITEM HAS BEEN ELEC7RONICALLY SIGNED AND SEALED USING ADIGITAIL SIGw41uRE_ PRINTED COPIES OF T-IIS DOCUMENT ARE NOT CONSIDERED 5IGNEOAND SEALED AND THE SIGm7uRE MUST SE VERIFIED ON ANY E L E �,TRONIC COPIES. Drawn by: FAHC ed by: RRG Project Number: Date: 17451031 0412412023 5hee: No. K11=1 07 a KELLER a 100 STICKLE AVENUE ROCKAWAY, VJ D7866 975-627-2100 1f4" • BRASS 2" PVC BALL PVC CHECK BALL VALVE VALVE VALVE PUMP CQNIRpL WVVW.KELLER-NA.COM PANEL — V N. INSTALL GRADE � EXISTING GRADE Dw—1 +a33 ® Y DW-2 +834 �_ 0 4 7BALL BALL W W c� VALVE VALVE JCO GROUND SURFACE J 2 (VARIES) EdL E] r .., • '' 2' 0 PVC SCH40 W 0 • WELL CASING W � �..I � � 6 0 HDPE 0 4 r. DISCHARGE MANIFOLD a� 4: •. • L F , 4" 0 PVC SCH40 CL WELL CASING . (SOLVENT WELDED) UP TO 50 FEET,Cn . 1A PACK FILTER I BOTTOM OF ASH O C (D5) OR TO PRACTICAL ' DRILL REFUSAL, WHICHEVER ANNULAR SEAL #r IS ENCOUNTERED FIRST UP TO �7 FEET, 4" 0 SCH40 WELL SCREEN Engireer of Record: BOTTOM OF ASH, . OR TO PRACTICAL 0.020" SLOT SIZE " DRILL REFUSAL, WHICHEVER — (SOLVENT WELDED)• :' L:.' IS ENCOUNTERED FIRST 1A FILTER PACK (D51) 2 0 SCH40 PVC 7.4_L• _ DISCHARGE PIPE t (SOLVENT WELDED) GRUNDFOS ZSS07-5 r. 2' 0 SCH40 PVC SUBMERSIBLE PUMP s 0.020' SLOT SIZE ,. i': WELL SCREEN M ❑ .� 0.75" 0 SCH40 U _ PVC STILLING TUBE �'r, °:• (SOLVENT WELDED) . • r t --' THIS ITEM FINS BEEN ELEC7RONICALLY tz ¢+ SCH40 t� .k' SIGNED AND SEALED USING ADIGITAIL rt. 4* CAP -f:rr {` PVC CAP SIGNATuRE_ 4 , y +• + ti' Y PRINTED COPIES OF T-IIS DOCUMENT ARE N47 CONSI❑ERED SIGNEDAND 0 APPROX. 6"0 SEALED AND THE SIGNATURE MUST SE APPROX_ 8 BOREHOLE BOREHOLE BOREHOLE ON ANY ELECTRONIC C4PIE5. Drawn by: Checked by: RRG AHC CL Project Number: Date: DEEP WELL DETAIL OBSERVATION VNEL-L- DETAIL 17451031 04124f2023 SCALE: N/A SCALE: N/A 5hee: Na. f� K11-1 08 .., . �� .. ,'w_� _ _ ,.. � _ � , .. 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