NC0024406_Waste Load Allocation_19820203

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Facility Name:
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NPDES WASTE LOAD ALLOCATION3�D%
-_\� LUS I C _ S+P_� rn 5 �• Date: 81. :-:-
Existing L91 Permit No.: AC6O 2-Y4)-0 �C Pipe No.: ounty: ;:2
Proposed E iTnictsi relbc,#,*F" a-�-
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Design Capacity (MGD): /,a2 Industrial (% of Flow): Domestic (% of Flow): t
Receiving Stream -ba % "• Jer Class: Sub -Basin:
Reference USGS Quad: (Please attach) Requestor: :1&1l[ MITS Regional Office Ee
==� (Guideline limitations, if applicable, are to be listed on the back of this form.)
Design Temp.: Drainage Area: `?'.C� I f" Avg. Streamflow:
7Q10: 4s Winter 7Q10: 30Q2: - 1'37� 02
PS
Location of D.O.minimum (miles below outfall):
Slope:
E Velocity (fps): Kl (base e, per day, 200C): K2 (base e, per day, 200C):
R
V
V
Effluent -
Characteristics-
Monthly N -x
.Average ptf14r
Comments
Comments
N:Characteristics
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Original Allocation For `%bus 10C4' 1ft
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luent
Monthly
Average
Comments
N:Characteristics
'qty_...
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Revised Allocation Date(s) of Revision(s)
(Please attach previous allocation)
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For Appropriate- Dischargers, List Complete Guideline Limitations , Below, '
Effluent
Characteristics
Monthly
Average
Maximum Daily
Average
Cokm'ents
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Effluent Guideline
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Form #001.
#369
WASTE LOAD ALLOCATION APPROVAL FORM
Facility Name: Duke Power Co. - Belews. Cr. Steam Station
County: Stokes Sub -basin: 03=02-01
Regional Office: Winston-Salem Requestor: Bill Mills
Type of Wastewater: Industrial
Domestic 100
If industrial, specify type(s) of industry: Ash Pond Discharge
Receiving stream:' Dan River Class: A -II
Other stream(s) affected: Class:'
7Q10 flow at point of discharge: 96 cfs
30Q2 flow at point of discharge: 187.2 cfs
Natural stream drainage area at discharge point: 501 mi2
Recommended Effluent Limitations
Monthly Average
Qw = 12 MGD
TSS = 30 mg/l
Settleable solids
= 0.1 ml/l
Max. Daily Average
100 mg/l (note: - daily avg. of - BPT
50 mg/l if due to source
body)
0.1 ml/l - BPT
Oil & grease = 20 mg/1 - BPT
15 mg/l
pH = 6-9 S.U.
Selenium = 0.1 mg/1
Arsenic - 0.47 mg/l
This is for a proposed relocation of an existing discharge.
- BPT
- WQ
This allocation is: /-X/ for a proposed facility, see attached description for
for a new (existing) facility the selenium limitations
F/ a revision of existing limitations
a confirmation of existing limitations
Recommended and reviewed by:
• Date: 3 a
Head, Techncial Service Brah Date: 13 / �--
Reviewed by:
Regional SupervisorDate: 3
Permits Manager •�•J Date:
Approved by:
Dater
Division Director

Development of Selenium Limit for Proposed Duke Power Co. Belews Creek Steam
Station Ash Pond Effluent Discharge into the Dan River.
The Selenium limit of 0.1 mg/1 for the Belews Creek Ash Basin effluent
was calcualted from a mass balance equation. The limit is based on an ambient
water quality standard of 10 ug/l, and 30 -day 2 -year low flow conditions.
Selenium sources considered in the mass balance equation are upstream,
ash pond, and Belews Creek. The upstream concentration of Se was assumed to
be 1 ug/l. Duke Power also used this value in their calculations, stating that
"Natural Se concentrations in surface waters of non -seleniferous areas are
variously reported to be in the range of 1 ug/1 or less.... USGS data indicate
that Se concentrations average less than 1 ug/l in North and South Carolina
streams ...." (Draft - "Environmental Impact Assessment: Discharge of Belews
Creek Ash Basin Effluent to Dan River"; Duke Power; April, 1981; pg.6). The
upstream flow at 30Q2 was estimated to be 187.2 cfs. For station 02.0690.0000
on the Dan River, the USGS has estimated a 30Q2 of 208 cfs, + 20%. To be
conservative, the figure of 187.2 cfs was calculated from 208 cfs - 10%.
Belews Creek was also considered to be a source of selenium. Although
the selenium level in Belews Lake should eventually return to the natural
background concentration, there should be, for some time, a discharge to
Belews Creek of selenium at the current in -lake level. This concentration was
calculated from Duke Power monthly average data for the past 2 years. The
Belews Creek flow was assumed to be 10 cfs, which is the minimum required
release for the for the dam. Se loading from Belews Creek could at times
exceed that assumed. However, stream flows during these periods will likely
be greater than 30Q2 levels.
The mass balance equation methodology and the ash pond effluent limit
of 0.1 mg/1 Se assume that the most critical point of selenium concentration
would occur below the mouth of Belews Creek, just slightly downstream of the
proposed discharge point. The underlying belief is that the selenium levels
in the discharge would be increasingly diluted going downstream. However,
there exists the potential that the most critical point for selenium would

occur, after a period of time, in Kerr Lake. Detention time in Kerr Lake,
and accumulation of selenium in the waters and sediments have not been explored.
In addition, the contributions of selenium from the CP&L Hyco Lake facility,
and the proposed CP&L Mayo Lake facility have not been considered. These
power -generating facilities also have selenium in their ash pond effluent,
and are located even closer to the Kerr Reservoir. In the future, the
question of Se levels in Kerr Lake needs to be further reviewed, with
consideration of all the upstream Se sources. .

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DIVISION OF ENVIRONMENTAL MANAGEMENT
l:: .f • : ,ily
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T0: Russell Radford �L,
FROM: Forrest Westall Z'ev i�7 &VL
SUBJECT: Wasteload Allocation for the Proposed Duke Power Ash Pond
Discharge to Dan River
Attached is the subject approval form for this discharge. Please note that
there is a description of how selenium limits were developed for the discharge.
We believe that the limits will adequately protect the .01 mg/l standard for
selenium in the Dan River. As the report indicates, however, the impacts of
selenium discharge to the Dan River on Kerr Reservoir have not been extensively
examined. In addition, the implications of this discharge on the CP&L Roxboro
(Nyco) and Mayo facilities have not been fully examined.
Under existing State rules, the discharge of selenium to the Dan River in
amounts capable of meeting the standards cannot be excluded from consideration.
My purpose in pointing out selenium impacts on Kerr Reservoir is to provide
an impetus to closely monitor selenium in the upper reaches of the lake. As
you know, Duke Power, in their studies of Belews Reservoir, has shown
significant impact from selenium at levels well below the .01 mg/l standard.
Therefore, it is appropriate to factor this consideration into our program.
As a point of information, I am sending a copy of this memo and attached
material to the Raleigh Regional Office.
Per your suggestion, a limit for arsenic has also been included in the
allocation. This limit will protect the Class A -II water quality standard
of 0.05 mg/l in the Dan River. Since arsenic is not as biocumulative as
selenium, we do not feel that it poses the same potential problem for Kerr
Lake that selenium does.
If you have any questions concerning this, please let me know.
FRW:cs
Attachments
cc: R. W. VanTilburg - w/attachments
Jennifer Buzun
Steve Tedder
L. P. Benton, Jr.
Bill Hills