NC0003417_Wastewater Decent Authorization & Provisions_20170908

DUKE
ENERGY.
September 8, 2017
Jeff Poupart, Section Chief
Wastewater Permitting Section
NC Division of Water Resources
1617 Mail Service Center
Raleigh, NC 27699-1617
RECEIVEDUDEWWR
SEP 13 2017
Water Quality
Permitting Section
Subject: Wastewater decant authorization and provisions
H.F. Lee Energy Complex
Permit 4: NC0003417
Wayne County
Dear Mr. Poupart,
As we work to safely close ash basins across our state, Duke Energy requests additional clarity
on the physical/chemical (P/C) treatment detailed in your July 20, 2016 letter regarding the
decanting of coal ash basins. Our company shares the state's commitment to perform this work
in an expeditious manner and in a way that protects people and the environment, while also
managing costs.
As background, the initial characterization of the ash basin free water was submitted to your
office in March 2015. We closely manage the dewatering process through continuous
monitoring, routine water testing and automatic pump controls. The latest water sample was
taken August 16, 2017. When compared to constituent limits in the current permit and proposed
limits derived by your staff in the station's DRAFT NPDES permit, it is clear that release of this
water at a controlled rate is in compliance and does not require additional advanced treatment in
order to assure that water quality in the receiving water body continues to be well protected.
We are asking you to confirm that compliance with permits is the measure that should be used to
determine if further discharge water treatment is required. This is consistent with well-
established historic guidance that effectively protects the environment.
Duke Energy also requests the Department include clarification in a modified decant
authorization that allows for ash basin levels to be lowered in excess of one foot per week, if
approved by the Department's Dam Safety personnel. This is consistent with authorizations for
other sites.
In doing so, we can safely and more expeditiously dewater basins and avoid the expense and
time required to build an unnecessary water treatment system. While dewatering is essential to
preparing for basin closure, it also brings other benefits to the environment by reducing seeps
and improving groundwater, goals shared by Duke Energy and the state.

Mr. Jeff Poupart
September 8, 2017
Wastewater decant authorization and provisions
Duke Energy will continue to maintain the system in which in line TSS and pH monitoring is
employed while decanting is ongoing if requested by the Department. Duke Energy will also
assure that any needed permit authorizations are in place and complied with prior to discharge of
interstitial water.
If there are any questions about this matter please feel free to contact me at [phone] or
shannon.Ian gley a,duke-energy.com.
Sincerely,
E. Shannon Langley
Lead Environmental Specialist
Attachment — HY Lee ash basin free water Sampling data
Cc: Sergei Chernikov —DWR w/attachments via email
Steve Cahoon/Filenet — Duke Energy w/attachments via email
Mike Graham — Environmental Field support, HF Lee

HF Lee Ash Basin Free Water Chractenzation
Date pH TSS P 0&G As Se TKN NO2/NO3 Total N Cd Cr Cu Pb Zn Hg TDS
std units mg/L mg/L mg/L ug/L ug/L mg/L mg/L mg/L ug/L ug/L ug/L ug/L ug/L ng/L ug/L
21 -Apr -16
29 -Apr -16
5 -May -16
11 -May -16
20 -May -16
26 -May -16
2 -Jun -16
9 -Jun -16
16 -Jun -16
23 -Jun -16
30 -Jun -16
7 -Jul -16
16 -Jul -16
16 -Aug -17
71
76
0 015
<5
595
149
024
<01
024
<1
<1
307
<1
906
1 64
120
87
<5
<5
128
154
034
<01
035
<1
<1
1 72
<1
<5
1 06
140
85
<5
0 012
<5
152
150
029
002
031
<1
<1
1 73
<1
<5
082
140
85
165
145
027
<01
027
<1
<1
158
<1
<5
0 969
150
87
<5
1
<5
184
14
025
< 01
025
<1
<1
137
<1
<1
074
150
76
103
125
023
< 01
023
<1
<1
<1
<1
<5
0 528
150
76
5
001
<5
104
125
020
< 01
018
<1
<1
<1
<1
<5
ND
150
79
117
107
019
< 01
017
<1
<1
<1
<1
<5
0 557
170
75
<5
<5
892
112
019
< 01
020
<1
<1
<1
<1
<5
ND
180
73
1
137
116
024
< 01
025
<1
<1
<1
<1
<5
-RD
160
72
181
107
032
002
034
<1
<1
<1
<1
<5
075
150
71
<5
0 017
<5
228
928
035
< 01
035
<1
<1
131
<1
<5
11
150
70
256
868
037
< 01
037 1
<1
I <1
<1 I
<1
<5
164
170
<5
0 014
207
486
069
<0 01
069
<1
<1
<1
<1
<5
0 787
130
Current NPDES Permit Limits for Outfall 001
60to90 1 30 1 15
Draft NPDES Permit Limits Outfall 001
6 0 to 9 0 30 15 1 3295 1 398 469 234