NC0004979_COMMENTS_19950117

DIVISION OF ENVIRONMENT MANAGEMENT
January ' 17, 1995
k 1 10 IlTi
M.
THRU: Donald L. Safrit
Ruth Swanek
Carla Sanderson
FROM: Jacquelyn M. Nowell
SUBJECT: Response to Comments for Duke Power- Plant Allen Station
NPDES Permit No. NC0004979
Gaston County
The Instream Assessment Unit (IAU) has reviewed the comments in the November
23rd letter from the subject facility and have the following recommendations.
Part 1.A. Outfall 002 - Request for removal of Flow limit. - A review of the
effluent pages from previously issued permits does show that flow from Outfall 002has
not been limited in the past. Flow was sampled weekly but no numerical limit was given.
Ina memorandum from P&E, the rationale for using 11.6 MGD as the design flow was
given. Instream Assessment would not oppose the deletion of the numerical limit for flow
but for the purposes of calculating effluent limits and determining instream waste
concentrations the flow of 11.6 MGD will be used.
Revision of monitoring freauencies for Oil & Grease. TSS. Arsenic. and Selenium
- IAU' concurs with the request for reduction in monitoring frequency for these
parameters. Oil & Grease will be reduced from weekly to the previous frequency of
2/month. Arsenic and Selenium will be reduced from 2/month to monthly. Because these
parameters are limited is not recommended to sample them less than monthly.
Revision of Benzene Limit - The benzene limit was determined using mass balance .
equation and the water quality standard of 1.19 µg/1 for Class WS waters. The receiving
stream (South Fork Catawba River) is classified as WS -V. The stream flow previously -
used was 95 cfs based on 80 cfs minimum release from Mountain Island Lake plus 15 cfs
runoff. This streamflow has been used historically in the determination. of limits for the
Plant Allen Station. The design flow of 11.6 MGD (18 cfs) was used as the flow
discharge as reported in the renewal application.
Based on new flow information, the minimum average daily flow of 314 cfs from
the Mountain Island Dam will be used to calculate the benzene limit that should be placed in
the permit. Since the benzene standard is based on the human health criteria, the average
flow should be used to calculate the limit. Contact with Ms. Rudisill of Duke Power has
not generated a more appropiate average flow value and she concurs with the use of 314 cfs
for the benzene limit.
Allowable Benzene = (18 cfs + 314 cfs)(1.19110) = 395 = 21.9 = 22 µg/1
18 cfs 18 cfs

J
The monitoring frequency for this limit should be determined by ME based on State
regulations for this type of discharge. However, for the initial year of this groundwater
Memo to Sean Goris
page 2
remediation project, the sampling of twice per month for benzene does not seem to be
extensive.
Part III, Other Requirements. E. Chronic Toxicity limit. The limit was
calculated by determining the Instream Waste Concentration (IWC). The design flow used
was 11.6 MGD:
IWC = Qw (in cfs) -L8-= 118 = 0.159 * 100 = 15.9 = 16%
Qw + 7Q10 18+95 113
The additional sentence requested to be added at the end of the chronic toxicity form
concerning subjection to civil penalty should be reviewed by the Aquatic Toxicology Unit
before placing it in the permit.
If there any additional questions concerning this permit, please contact me.
cc: Rex Gleason
WLA File

DUKE POWER -ALLEN PLANT 9/27/94
SOUTH FORK CATAWBA RIVER/CATAWBA RIVER JMN
030834 & 030836
WLA#S 7990,7991,7992,7993,7994
Update 1/4/95
Facility has submitted letter requesting modification of some limits and monitoring
requirements in finalized WLA. Main concern was for benzene limit wanted the limit.
changed to same limit in the general permit. Based on the state standard for benzene into
WS Class waters of 1.19 µg/1 and using the minimum average daily flow release of 314 cfs
from Mountain Island Lake Dam with no runoff included (instead of the minimum
instantaneous release plus runoff of 95 cfs), the new benzene allowable is 22 cfs. Had
talked w/ J. Rudisill of Duke Power about an average flow release from Mountain Island
Lake. She had been unable to come up with an average flow release. She had gotten
information from the operating center that Duke Power has an agreement with WWTPs
downstream and public water supply to release enough water to produce 33 megawatt/day
or 5940 cfs/over an hour or 248 cfs/day (?) . She said that she felt comfortable with us
using 248 cfs or 314 cfs for calculation of the benzene limit.. Would send us the data on
the MW/day info. Called back to verify flow info. and she recommended that we use the
minimum average flow value, since she was having some trouble getting flow info in cfs.
Decided to use the 314 cfs flow value for benzene. JMN
9/27/94
The facility is requesting renewal of existing NPDES permit. Power plant has five outfalls,
but has previously only had limits for outfalls 001 & 002. Outfalls 003, 004 &005 have
not had permit limits before.
001 & 003 discharge to the South Fork Catawba River (030836).
002, 004 & 005 discharge to the Catawba River approximately 5 miles above Lake Wylie
(030834).
Outfall descriptions
QU - Condenser Cooling Water is once through, non contact cooling water that removes
heat rejected from the condensers and other selected heat exchangers. Avg flow 428.5
MGD. Max. flow 784.8 MGD.
AU - Ash basin discharge with sanitary waste and stormwater flows. Accomodates flows
from the yard drainage sump,coal yard sump, ash removal lines and rainfall runoff from
the basin watershed area. Avg. flow 11.6 MGD.
M3_- Once -through non contact cooling water withdrawn from the service water system.
the discharge consists of cooling water from Units 4&5 mill oil coolers, boiler feedpump
hydraulic coolers and other miscellaneous equipment cooling .
004 -- Equipment Cooling Water The discharge consists of cooling water from Units 1&2
mill oil coolers, boiler feedpump hydraulic coolers and other miscellaneous equipment.
Once -through non contact cooling water withdrawn from the service water system. In
addition water from a vehicle rinse -down area is directed to this outfall. The rinse water
contains no soaps or other additives.
005 - Water for the Unit 5 Condenser Cooling Water is filtered for Asiatic clams. These
clams, common in Lake Wylie can clog the condenser tubes. Max. flow of 3000 GPD. No
other additives are in the backwash water.

1,
1

Outfall 001- In new WLA, effluent guidelines recommend free available chlorine at. 0.2
mg/1 Mo. avg. and 0.5 mg/1 Da. Max. 40 CFR 423.13. Previous Limits include flow and
temperature w/ a monthly average of 35C (95F). During the period from June 1 to
September 30, 38.9 C (102 F) is allowed. No chlorination of the once -through cooling
water is allowed under this permit. Will recommend that free available chlorine limit be
added to renewed permit.
Outfall 002 -Ash Basin discharge
Effluent guidelines recommended include:
Mo. Avg. Da. Max.
TSS 30 mg/1 100 mg/1
O & G 15 mg/1 20.0 mg/1
Total Copper 1.0 mg/l 1.0 mg/1
Total Iron 1.0 mg/l 1.0 mg/1\
Previous permit had these limits and additional limits of 450 µg/1 of arsenic and 45 µg/1 of
selenium. Tox limit of 11 %. in JAMAPR,JUL, OCT.
DUKE POWER -ALLEN PLANT Page 2
In May 1994, IAU responded to Duke Power request to add GW remediation discharge to
the ash basin. Indicated that oil/water separator would be installed for treatment. We
recommended that limits and monitoring requirements for benzene, toluene and MTBE
would have to be added to the permit. A review of the current system does not show a
oil/water separator added as a treatment system. Staff report indicates that upon reissuance
of Permit, action will be taken on ATC for construction of oil/water separator.
New Allowable concentrations for 002
Arsenic= old limit = 450 µg/1. After new wasteflow, from 7.6 MGD to 11.6 MGD,
allowable concentration = 314 µg/1

Division of Environmental Management
MEMORANDUM
TO: Jackie Nowell-�
Rapid Assessment Group
TO: Mike Parker
Mooresville Regional Office
FROM: Sean D. Goris��
Permits and Engineering
SUBJECT: Duke PowerA ee Steam Plant (NCO004979) comment's on draft permit
DATE: 12/5/94
Please provide comments and recommendations regarding Duke's letter of November 23,
1994. In this letter Duke has raised a number of concerns regarding their draft permit.
In particular: (Please provide any comments you feel appropriate)
Mike: Please comment on the various measurement frequency requests and the
chlorination clauses. They claim that they do not chlorinate at the outfalls
mentioned. Also please comment on the BMP issue. I am not familiar with the
demonstration they site and would like any info. regarding this you can provide.
Jackie: Please comment on the measurement frequency requests and the benzene limit
request.

Duke Power Company
Generation Services Department
13339 Hagers Ferry Road
Huntersville, NC28078.7929
DUKEPOWER
4 ,,ENS o
OUI�POWHI
November 23, 1994
Ms. Coleen Sullins
Permits and Engineering
North Carolina Department of Environment,
Health and Natural Resources
P.O. Box 29535
Raleigh, North Carolina 27626-0535
Subject: Allen Steam Station
NPDES Permit Renewal NC0004979
Certified Z 309 002 146
Dear Ms. Sullins:
We have reviewed the draft Allen Steam Station NPDES Permit No. NC0004979
and submit for your consideration the attached comments. The effluent sheets
for outfall 002-004 are included to provide additional clarification for our
comments.
We appreciate this opportunity to provide comments. If you have questions or
need additional information, please contact me at the above address or (704)
875-5966 or John Carter [phone].
Sincerely:
Jennifer A. Rudisill
Assistant Scientist
Environmental Division, Water Protection
aft
cc: Mr. David A.Goodrich, DEHNR - Raleigh
Mr. Mike Parker, DEHNR - Mooresville Regional Office
Printed on recycled paper

COMMENTS AND RECOMMENDATIONS FOR DRAFT NPDES
PERMIT NO. NC0004979 FOR PLANT ALLEN
1. PART 1.A. OUTFALL 002:
We request that the flow limit of 11.6 MGD for the discharge be removed. After
conversations with the DEHNR staff, we believe that limiting this flow was an oversight.
Flow from this outfall varies greatly with unit demand as well as meteorological
conditions.
We request that the measurement frequency for Oil and Grease and TSS be reduced
from weekly to twice monthly as in the current permit. As Plant Allen has neither
exceeded nor approached its limits for these parameters during the previous 3 years,
we feel that the increased cost for the sampling and analyses is not justified.
We request that the measurement frequency for Arsenic and Selenium be reduced from
twice monthly to the previous permit requirements of quarterly. Once again, as Allen
has neither exceeded nor approached either limit, we feel that there is no justification
for the substantial increase in expense due to additional sampling and analyses. If this
is infeasible, we recommend that a clause stating that after 6 months of monthly
monitoring and meeting the limits for As and Se, the frequency be dropped back to °
quarterly.
We request that the Daily Limit for Benzene be increased from 7.5 ug/L to 142.8 ug/L
and that the measurement frequency be reduced from twice monthly to once a month.
This is consistent with the benzene monitoring requirements of the NC General Permit
for the discharge of petroleum contaminated groundwater (NCG510000). In addition,
we request a clause stating that monitoring for Benzene, Toluene and MTBE will not be
implemented until discharge of treated groundwater into the ash basin is initiated and
that monitoring for these three parameters be discontinued once the remediation effort
is ended.
2. PART I.A, OUTFALL 003:
We request that the discharge limit for Free Available Chlorine be replaced with the
clause:
Chlorination of the once through cooling water, discharged through outfall
003 is not allowed under this permit. Should Duke Power wish to
chlorinate its once through cooling water, a permit modification must be
requested and received prior to commencing chlorination.
3. PART I.A. OUTFALL 004:
We request that the discharge limit for Free Available Chlorine be replaced with the
clause:
Chlorination of the once through cooling water, discharged through outfall
004 is not allowed under this permit. Should Duke Power wish to

` chlorinate its once through cooling water. a permit modification must be
requested and received prior to commencing chlorination.
PART III, OTHER REQUIREMENTS:
E. Chronic Toxicity Pass/Fail Permit Limit: We request a copy of the calculations used
to determine the effluent concentration for the toxicity test.
We request that the following be added to the last paragraph of the test requirements:
, but will not subject the permittee to civil penalty if the permittee has
demonstrated a diligent attempt to conduct a suitable retest and has
engaaed the services of a laboratory with valid certification under North
Carolina's laboratory certification program.
We request that the following clauses be added:
H It has-been determined from information submitted that the plans and procedures in
place at Allen Steam Station are equivalent to that of a BMP.
I The applicant is permitted to discharge chemical metal cleaning wastes to the ash
basin under the conditions outlined in the 1976 Riverbend Ash Basin Equivalency
Demonstration and the 1994 Allen Steam Station permit application.
The above additions to Part III are consistent with permits issued by your office for
other facilities of this kind.

A. (). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS FINAL Permit No. NC0004979
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from
outfall(s) serial number 002. Such discharges shall be limited and monitored by the permittee as specified below:
Effluent Characterlstics
Flow
Oil and Grease
TSS
Total Copper
Total Iron
Arsenic
Selenium
Total Phosphorus
Total Nitrogen (NO2+NO3+TKN).
Toluene -'-A-E"
Discharge l.lmltatlons
Lbs/day units (speclfy)
Monitoring Reaulrements
Measurement
sample
Mon. AM Dally 'Max Mon. "AM Dally Max.
Frequency
Type
1111.6 NSB-
Weekly
Pump Logs or
15.0 mg/I 20.0 mg/I
—"WeeeW7-/mon`4h
Grab
30.0 mg/I" 100.0 mg/I
—Weekly--2IrYoa"h
Grab
1.0 mg/I
2/Month
Grab*
1.0 mg/I
2/Month
e A
Grab
314.0 g g / 1
--£im"tfr•Q LOLA
Grab
31.0 µ g / I
Quarterly "`rev ly
Grab
Grab
Quarterly
Grab
---5-rgf"I-14Z.q 1hr-,+h (y
Grab
Monthly
Grab
* Sample Locations: E - Effluent
** Chronic Toxicity (Ceriodaphnia) P/F @ 16.0%; January, April, July, October, See Part III, Section E.
E
E
E
E
E
E
E
E
E
E
E
The pH shall not be less than 6.0 standard units.nor greater than 9.0 standard units and shall be monitored weekly at the effluent by grab
samples.
There. shall be no discharge of floating solids or visible foam in other than trace amounts.
(Continued)
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A. (). EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS FINAL Permit No. NC0004979
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from
outfall(s) serial number 002. (Continued)
Effluent Characteristics Lbs/day Discharge Uniltations Monitoring Requirements
Other Units (specify) Measurement Sam IZe *Sample
Mon. AVa. Daily .Max Mon. Ava, Dally Max. Frequency IY" Location
MTBE ' Monthly Grab E.
Chronic Toxicity" Quarterly Grab E

A. O. EFFLUENT LIMITATIONS AND MONITORING REQUIREMENTS FINAL, Permit No. NC0004979
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from
outfall(s) serial number 003. Such discharges shall be limited and monitored by the permittee as specified below:
Effluent Characterlstics Lbs/day Discharge Limitations
Units (speclfv)
Mon. AVa. Dally 'Max Mon. Aya. Dally Max.
Flow
* Sample location: E Effluent.
Monitoring Reaulrements
Measurement Sample 'Sample
Frequency Type Location
-Weekly -Qrabr - - E—
Weekly Estimate E

A. (). EFFLUENT LIlVIITATIONS AND MONITORING REQUIREMENTS FINAL Permit No. NC0004979
During the period beginning on the effective date of the permit and lasting until expiration, the Permittee is authorized to discharge from
outfall(s) serial number 004. Such discharges shall be limited and monitored by the permittee as specified below:
Effluent Characteristics Discharge Wraltations Monitoring Requirements
Lba/day Units (s eq_cif0 Measurement Sample *$ample
Mon. AVq. Dally .Max Mon,.Am Daily Max. Frequency Type Locatlon
-Fret-�4yatta�te�orh�
Oil and Grease .15.0 mg/I 24.0 mg/I 2/Month Grab E
Flow Weekly Estimate E
* Sample location: E - Effluent.
(see oof{d 06

Division of Environmental Management
MEMORANDUM
TO: Permit File NC0004707, Duke Power, Plant Allen
Gaston County (Sub -basin 03-08-34)
FROM: Sean D. Goris SdC
Permits and Engineering
SUBJECT: Use of 11.6 MGD as the design flow rate for outfall 002
In previous permits, this outfall was rated at 7.6 MGD. This equated to an instream waste
concentration of 11%. Duke Power in their renewal application, received by the Division
June 2, 1994, reported the flow at this outfall to be 11.6 MGD. A review of monitoring
data over the past three years indicated this was a reasonable estimate of average flow from
the outfall. Therefore, this flow was recommended by Permits and Engineering in the
wasteload allocation request.
cc: Rapid Assesment Group

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