NC0000396_Request for Concurrence Release of Interstitial Water_20180418

etDUKE
., ENERGY. RECEIS
VED EHS CCP
PROGRES NR/DWR626 S Church St
APR 2 0 2018 Charlotte,NC 28202
April 18,2018 Water
Resources
Mi.Jeff Poupart, Section Chief Permittmg Section
NCDEQ,Division of Watei Resources
1617 Mail Service Center
Raleigh,NC 27699-1617
Subjects Duke Energy Progress, LLC
Asheville Steam Electric Generating Plant NC0000396
Request for Concurience.Release of Interstitial Water to Allow for Continued Ash Basin
Excavation
Buncombe County
Dear Mi.Poupart:
Duke Eneigy Progress, LLC (Duke Energy) is required by North Carolina General Statute to fully
excavate the ash basins at the subject facility Duke Energy has made steady progress-the 1982 basin has
been fully excavated the 1964 basin is on schedule to meet with the timelines required by law However,
Duke Energy is quickly reaching a point where continued excavation will requii e the removal of
interstitial water It has been determined that Duke Energy will t each the end of dry ash excavation by
June 2018
In order to continue ash basin excavation and meet statutory deadlines, Duke Energy pioposes to dewater
the 1964 ash basin via an ari ay of 10 deep wells This system is expected to generate flows of
approximately 250 gpm (0 36 MGD) This additional wastewater would be a nominal increase (6.9%) in
the average wastewater discharge of 5 18 MGD from the site. Characteristics of the extracted water are
largely comparable to historic and current ash basin wastewater flows. Sampling iesults are attached to
this letter for your reference Based on the relatively small flow contribution and similar wastewater
quality, Duke Energy does not believe that the addition of this waste stream poses a significant change to
the character of wastewaters currently authorized to be discharged under the NPDES permit for the
Asheville plant(pending renewal since 2010)
If upon review of this data, the Division believes that the addition of this wastestream poses a significant
change to the quality of wastewaters having the potential to be discharged, Duke Energy would propose
to pretreat extracted water to ensure that the interstitial water being released from the permitted ash basin
system is similar in character to current operational flows.
Duke Energy requests the Division concurrence and guidance concerning this important issue Should
you have any questions regarding this letter or require additional information, please contact Ms. Tina
Woodward at(704)382-4585 or at Tina Woodward@Duke-Energy coin.
Sincer y,
Richard Baker,Director
EHS CCP Environmental Programs

Duke Energy Pi ogress, LLC
Asheville Steam Electric Generating Plant
Request for Concurrence of release of Interstitial Water under existing permit
April 18,2018
cc: Sergei Cheriiikov
Complex NPDES Permit Supervisor
1617 Mail Service Center
Raleigh,NC 27699-1617
Landon Davidson
Asheville Regional Office Supervisor
2090 U S Highway 70
Swannanoa,NC 28778

L;TypicaOufa0q1?Aj .,ti , - " ` ' 6413:asin lnoi;stial. _s „ "a =PoectedOu Fa .v1 4,
*':y ,,Percent;
edCn,, 1Non , ` - ,Existin ,,,Conc0ntratios' Concentrations . '46Okim - oricetatis .1% Change
Flow 2,800 gpm Flow 250 gpm Flow 3,050 gpm 8 9%
Arsenic 100 ppb Arsenic 360 ppb Arsenic 121 3 ppb 21%
Oil and Grease 9 3 ppm Oil and Grease 0 ppm Oil and Grease 7 7 ppm -18%
Nitrate/Nitrite 108 ppm Nitrate/Nitrite 0 ppm Nitrate/Nitrite 1.0 ppm -8%
Chloride 182 44 ppm Chloride 10 6 ppm Chloride 168.4 ppm -8%
Fluoride 0 97 ppm Fluoride 0 8 ppm Fluoride 1.0 ppm _1%
Sulfate 234 33 ppm Sulfate 175 4 ppm Sulfate 229.5 ppm -2%
Aluminum 1480 ppb Aluminum 165 3 ppb Aluminum 1372 2 ppb -7%
Barium 350 ppb Barium 156 9 ppb Barium 334 2 ppb -5%
Boron 4350 ppb Boron 987 4 ppb Boron 4074.4 ppb -6%
Calcium 113500 ppb Calcium 81860 ppb Calcium 110906.6 ppb -2%
Iron 420 ppb Iron 7670 ppb Iron 1014 3 ppb 141%
Magnesium 35450 ppb Magnesium 19216 ppb Magnesium 34119.3 ppb -4%
Manganese 210 ppb Manganese 3387 ppb Manganese 470 4 ppb 124%
Zinc 30 ppb Zinc 0 01 ppm Zinc 27.5 ppm -8%
Anitmony 10 ppb Anitmony 9 1 ppb Anitmony 9.9 ppb -1%
Cadmium 0 ppb Cadmium 0 2 ppb Cadmium 0.0 ppb No Change
Chromium 10 ppb Chromium 16 ppb Chromium 9.3 ppb -7%
Copper 20 ppb Copper 1 4 ppb Copper 18 5 ppb -8%
Molybdenum 160 ppb Molybdenum 1815 ppb Molybdenum 161.8 ppb 1%
Nickel 20 ppb Nickel 16 7 ppb Nickel 19 7 ppb -1%
thallium 10 ppb thallium 2 8 ppb thallium 9.4 ppb -6%
TSS (Sample Oct 17) 7 04 ppm TSS 33024 ppm TSS 2713.3 ppm 38442%
TSS (Sample Mar 18 ) 7 04 ppm TSS 106 ppm TSS 15.2 ppm 115%
TDS 640 ppm TDS 488 ppm TDS 627.5 ppm -2%
Total Hardness 429 5 ppb Total Hardness 698 4 ppb Total Hardness 451 5 ppb 5%
Mercury 0 002 ppb Mercury 0 0005 ppb Mercury 0.002 ppb -6%
Selenium 50 ppb Selenium 10 ppb Selenium 46.721 ppb -7%

Current
French Broad Make-Up Consumptive
RiverWater Intake Loss Stormwater >1-942-Ash-Rand
_
IStormwater flow has
vX Flue Gas been redirected T >Dam Seepage
DSettling ' Desulfurization V > Clarifier ____,
Zone — Ultra-Filtration
System (future)
> Units 1 &2 S ' Lake ,l,Julian
Condensers Outfall 002 Public
Lake N s Intake 1
B Sewer
Julian Structure > Circulating Water F > Ash Sump System
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i
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teat
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iL
R Chemical Metal
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A water treatment gt = £°� o G
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(Alt)
Turbine Site M v__, > Duck v < ,r Z
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> Low Volume ' Rim Ditch & F--
> Waste Sources Ash Pond 1964 > Polishing Filter Secondary French Broad
A A A --- --> River
Basin A Outfall 001
Storm Water K J H
Groundwater Groundwater Extraction
Extraction (Option B) W Coal Pile Dam (Option A)
Public Potable andC Public Runoff Seepage
Water > Sanitary > Sewer
Supply System System
V
MSD Evaporation