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Home My WebLink AboutCCB0031_DukeMarshall_South Stability Feature_Phase I Dewatering Wells_FID1814835_20230810(' DUKE ENERGY-. August 10, 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) 526 South Church St. Charlotte, NC 28202 Mailing Address P.O. Box 1006 Mail Code EC 13K. Charlotte, NC 28201-1006 Re: South 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, 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 southern 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: • Fifteen (15) deep dewatering wells, • Thirteen (13) shallow dewatering well points, • Three (3) deep observation wells, and • Three (3) 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 South Stability Feature Plan View and Cross Section — Phase I Dewatering Well Drawings - KI I-301, KI I-302, KI I-306, and KI I-307 (Keller, 2023) cc (via e-mail): Claire Osborn, 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 Strxtural Fill CCBOQ31Sourh StatdlityFealture Proposed Dewatering Well ConstruttioniDetails Appro.. Ground _ Plopoied az.rerter:,a 5urlrae Line Number '4P P��- Wet +tPProti Well Well Se" W"e een We�saleen Well Llile stee;}n Lenph aeptn SP i oeptf�ItanRe Sequence Method Elevatlon (it1 of Devkrs Ift hg5-1 [tf. on mMen tengfth'Rj @ft. bei.1 Lue•lien It[ r J.] —Ami De -Am i r DWA Weill Sto{ 834) 1550 :. 35 58 20 1%10 35 witee pW2 Oaffbi inq 20 Is. to15 A i't Wells t4'P7L Wellpel Ms S.W.R7, 130 ]I 75 ld 10 SS le 25 Ash pa. e W a*i Cwr P oaWlm 46dEf+ua,iJ li S.?-. 826 I;'a i 25 M1/3 -10 151025 +sn pole Ww_a WO Is witA Shafow _ Observation 7.:- 8L1 rra s 24 N� 1D 151025 SOW-6-6 xrlh Wade NOTES 1, DISCHARGE FROM THE DEWATERING SYSTEMS WILL HE KEPT WITHIN THE ASH BASIN AND PUMPED THROUGH THE ` TREATMENT SYSTEM PRIOR TO DISC ARGE THROUGH NPDES MFALL 002. 2. ALL WELLS WILL BE KE'T WITHIN ASH BOUNDARY. �er LEGEND 0 DEEP DEWATERING WELL — EXISTING MAJOR 7:77_ TOPOGRAPHIC CONTOUR • WELLPOINT EXISTING MINOR DRILLED DEEP OBSERVATION WELL TOPOGRAPHIC CONTOUR HAND JETTED SHALLOW — — — ASH BASIN BOUNDARY OBSERVATION WELL (APPROXIMATE) = DW HEADER PIPING .............. ILF PHASE LIMIT (APPROXIhAATE) WPT VACUUM HEADER PIPING EXISTING SITE FEATURE — DISCHARGE PIPING .............. (APPROXIMATE) l 4 ;t`, } � ti S►lt}j 1�l i l� ki�1 I � 17 • �,�y �xt�s15'�14` {t��ke QVLRALL SITE PLAN SCALE: 1' = 1 CO' TO DISCHARGE SYSTIM TO 3YSTEIA = 4210ft 424ft + 5DOft = 924k TOTAL DISCHARGE (SEE NOTE 1) :Z1, >StJ1i� i' a. ioC r o nor zao' F SHEET IS LESS TWA Vr x I I' WALE AICCVRUNGLY aC a 100STICKLE AVENUE ROCKAWAY, NJ 07866 973-627-21 OO WINW-KELLER-NA-COM a J M/ } — CL Q ❑ g LL LLJ L f Q �U y"t rn Engineer of Record: TH15 ITEM HAS BEEN ELECTRONICALLY SIGTQFD AND SEALED uSING A DIGITAL $IGfNATURE. PRINTED COPIES OF THIS DOCUMENT ARE NCT CONSIDERED SIGNEDAND $EALEE, AND THE SlQkATURE MUST BE VERIFIED ON ANY ELECTRONIC CORES. Drawn by. Checked by: RRC I AHC Project Number; Data: 17451031 0611912023 Sheet No- IIm01 saa 91� Il10 1i00 IAO B� SAO B78 IFM B00 790 7W 770 790 O}00 1+00 2+00 34W 4+00 5+00 d+00 7+00 C 40 G1 a E SECTION A —A Y PRE -PHASE PHASE a HORIZONTAL SCALE: 1' = 100' m VERTICAL SCALE: I' = 50' Y SF SOUTH: INITIAL PRE —PHASE (PHASE 1) CROSS SECTION A —A 3TACKE6 EYISTINC OiE�4OE � � O 4 I ` TARGET REk-IC SURFAiM DNI S -1 DUN-2 ESTIMATE] BOTTOUC F ASH 815 FT -- D4N-3 901F16 EL_ Bun FT 93.0 220 910 900 $90 870 8so Wo 840 8Z4 810 800 790 780 7n M d440 S+00 10+00 11+00 LIZUawa ' — DOTTOM Or AS" ------- FY�fiT.atcc�rAaE PROPOSED CRAVE TARGET P74REATIG CAM aC a 100STICKLE AVENUE ROCKAWAY, NJ 07866 973-627-2100 W1NW_KELLER-NA_COM a w — 3 < M cm = � �o C LL E L) GlfC _ � CD } 1__I o g L Q L m f LU L) Engineer of Record: TH15 ITEM HAS BEEN ELECTRONICALLY SIGTQED 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 vUCTcu SC E, r - 5v RRC AHC o So' 1W Project Number; Data: iiiia 17451031 0611912023 HORIZONTAL SCALE- 1• - 18O' Sheei No- 1 _ Kllm302 MEN" IFSHEET IS LE SE THAN r X 1 1' SCALE ACCORONGLY INSTALL GRADE WPT-1 +815 WPT-2 +815 WFT-3 +823 JP TO 25' BGS OR T4 PRACTICAL REFUSAL. WHICHEVER 15 ENCOUNTERED FIRST 1 _5' 0 VAL VF TEMPORARY SCH40 PVC VACUUM HEADER 2"0 SCH40 PVC WELL SCREEN 0.020" SLOT SIZE #1A FILTER PACK (DSI) 1.25" 0 SCH40 PVC DRAWDOWN TUBE APPROXIMATE 6-0BOREHOLE TYPICAL WFLLPOINT DETAIL SCALE: N/A UP TO 25' BG5 OR TO PRACTICAL R15EFUSAL WHICHCVER EINcbLJNTERED 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 (SOW-1 to SOW— 5� SCALE: N/A 100 STICKLE AVENUE ROCKAWAY, VJ D7866 975-627-2100 WVVW.KELLER-NA.COM J r� �0 Z -W 0 0 M C a:=� �r (D E_ w J CD __ CL � M � 0 �_ CIO 2 cts 06 w IL CL W LCn Engireer of Record: c 2 C.] t: 4 z t a LL i17 - PRELIMINARY - NQT FOR CONSTRUCTION THIS DOCUMENT IS RELEASED FOR THE PURPOSE OF INTERIM REVIEW_ IT IS NOT TO BE USED FOR CONSTRUCTION THIS ITEM HAS BEEN ELECTRONICALLY SIGNED AND SEALED USING ADIGITAL SIGw41uRE_ IPRINTED COPIES OF T-IIS DOCUMENT I ARE NOT CONSI❑ERED 51GNEDANQ SEALED AND THE SIGHATuRE MUST SE VERIFIED ON ANY E L E �,TRONIC COPIES. RR(: Drawn by:I AHC Checked by: I Project Number: Date: 17451031 0611912023 5hee: No. Kllm306 INSTALL GWE DW-1 +830 DW-2 +823 Pt1MP CONTROL PANEL SURTACE ARIESj UP TC 35 FEET, BOTTOM OF ASH, OR TO PRACTICAL DRILL REFUSAL, WHICHEVER IS ENCOUNTERED FIRST 1/4- 0 BRASS BALL VALVE 20' 2` PVC BALL VALVE PVC CHECK VALVE r,H 2' PVC BALL VALVE 5 if .1a V 4' 0 PVC SCH40 WELL CASING (SOLVENT WELDED) rr J I A FILTER PACK (OSI) 4' 0 SCH40 WELL SCREEN •: p 0.020' SLOT SIZE (SOLVENT WELDED) 2- 0 SCH40 PVC ' DISCHARGE PIPE .•'+.' (SOLVENT WELDED) GRUNDFOS 25SD7-5 ' ,•' ' SUBMERSIBLE PUMP r «• 0.75' 0 SCH40 ' _ PVC STILLING TUBE (SOLVENT WELDED) ' •, .. •r' 4- 0 SCH40 PVC CAP _ APPROX. 8" 0 ®OREHOLE DEWATERING WELL DETAIL SCALE: N/A 2" PVC BALL VALVE 6' 0 HDPE DISCHARGE MANIFOLD UP TO 30' BG5 OR TO PRACTICAL REFUSAL WHICHE-VER IS ENCbUNTERED FIRST PAD 2'0 SCH40 PVC WELL SCREEN 0.020' SLOT SIZE 0 1 A FILTER PACK (DSI) 'VC CAP :I HATE v-unl v- TYPICAL DEEP OBSERVATION WELL DETAIL (DOWN-1 to DQW-3� SCALE: N/A 100 STICKLE AVENUE ROCKAWAY, VJ D7866 975-627-2100 WVVW.KELLER-NA.00M C] J Z < F- r J Q � LU J � c 2 L : LL. W r37 00 L rLLLl L W F_ LU Cn 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: Checked by: RR(: I AH0 Project Number: Lake: 17451031 06119/2023 5hee: No. Kllm307