FA-8008_43227_M_DENR_20221115_Extension Approval

From:Currie, Ken
To:Mike Hays
Subject:RE: [External] RE: Duke Energy Blewett Falls_Incident No. 42237_Update
Date:Tuesday, November 15, 2022 12:00:00 PM
Attachments:image002.png
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Mike,

Extension approved for 12/31/22 on the IAA report.

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From: Mike Hays <[e-mail]>
Sent: Tuesday, November 15, 2022 9:53 AM
To: Currie, Ken <[e-mail]>
Subject: [External] RE: Duke Energy Blewett Falls_Incident No. 42237_Update

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Good Morning Ken, In the last update I provided for Duke Energy Blewett Falls (see below) I said we’d get you theInitial Abatement Action (IAA) Report today (11/15/22). Preparation of the report is progressingwell, however it’s not ready for submittal. I respectfully request an extension until 12/31/22 tosubmit the IAA Report. I apologize for the delay. Best Regards, Mike
Mike Hays
Mobile [phone]
From: Mike Hays
Sent: Monday, October 17, 2022 10:30 AM
To: Currie, Ken <[e-mail]>
Cc: Gilbert, Christopher <[e-mail]>; Young, Emily
<[e-mail]>; Parish, Ty C <[e-mail]>; Blair Burgess
<[e-mail]>
Subject: Duke Energy Blewett Falls_Incident No. 42237_Update
Hello Ken, On behalf of Duke Energy, I wanted to provide you with an update on the progress of theBlewett Falls Development Project since the submittal of the last update in July, 2022. DukeEnergy and ERM have conducted the following activities associated with release Incident 42237since July 2022: Excavation for the fish passage construction resumed July 7, 2022, which includesconcurrent Support of Excavation (SOE) Wall construction activities. The attached recentaerial photo illustrates the current excavation footprint of the Blewett Falls DevelopmentProject.Excavation of the fish passage footprint is on-going and has reached an approximateelevation of 120’ (surface elevation near the powerhouse in the vicinity of the former USTsis approximately 153’). The target depth for the excavation is 100’ elevation. The maximumdepth of soil impact related to the UST Incident is 135’ elevation.During excavation activities within the impacted soil zone, removed soils were fieldscreened in real time by ERM for evidence of impact using PID headspace, visual, andolfactory observations. Excavated soils that exhibited signs of impact were segregated andtransported to a landfill for proper disposal. A total of 457.80 tons of impacted soil hasbeen disposed at the Waste Connections Anson Landfill in Polkton, NC since October2021.Groundwater dewatering for the fish passage construction activities was initiated in April2022.The system has run continuously since start up with the exception of minordowntime for maintenance.NCDEQ DWR has conducted site visits to inspect the groundwater dewateringsystem on May 3, 2022 and July 21, 2022 and found no discrepancies.As of October 3, 2022, since startup 5,952,008 gallons of groundwater have beenextracted and discharged. The water table elevation in the construction area hasbeen lowered approximately 30’-35’ to date, and is currently below the zone ofpetroleum impacted soil.Dewatering system influent/effluent sampling for Turbidity, Total Suspended Solids, andTPH DRO in accordance with the dewatering and discharge plan has occurred periodicallystarting April 22, 2022 (influent/effluent sampling bi-weekly until July 2022, followed byeffluent sampling monthly to date).TPH DRO was detected in the influent sample above the laboratory reporting limitin the initial sample collected April 22, 2022.Subsequent sampling events have not detected TPH DRO above laboratoryreporting limits in either the influent or effluent samples.Turbidity and TSS concentrations have been below laboratory reporting limits orregulatory reporting limits for all sampling events.In consideration of the influent/effluent sampling data, Duke requested that theNCDEQ DWR approve modification of the Dewatering and Discharge Plan to
reduce the components of the water treatment system. NCDEQ DWR approved thisrequest in July 2022. As referenced above, the overall excavation for the fish passage construction activities is currentlyon-going with completion projected 1Q 2023. A portion of the original proposed remedialexcavation area is included within this larger excavation. Upon substantial completion of the fishpassage construction (or sooner if practical) replacement monitoring wells will be installed withinthe USTs release area and subsequently sampled. ERM is preparing a report for submittal to the NCDEQ documenting the USTs removal, soilsampling, and soil analytical data related to the fish passage construction excavation activities. The report will be submitted on or before November 15, 2022. A subsequent report will be prepared and submitted to the NCDEQ at a later date documentingthe replacement monitoring wells installation and groundwater analytical data. If you have any questions or need further information please feel free to contact either ChrisGilbert of Duke Energy or myself. Best Regards, Mike
Mike Hays, P.G.
Principal Consultant, Geologist
ERM NC, Inc.
300 West Summit Avenue, Suite 330 | Charlotte, NC 28203
Mobile [phone]
[e-mail] │www.erm.com
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