NC0038377_Comments to Draft Permit_20051108

�J Progress Energy
NOV 0 8 200
Mr. Sergei Chermkov, Ph.D
North Carolina Department Environment and Natural Resources
NPDES Unit
1617 Mail Services Center
Raleigh, NC 27699
File. 12520 B-1
RE Mayo Electric Generating Plant
National Pollutant Discharge Elimination System Permit No NCO038377
Comments to Draft NPDES Permit
Dear Mr. Chernikov-
Attached are our comments on the subject draft NPDES permit. We appreciate the opportunity
to comment. If you have any questions concerning this matter, please contact Mr Steve Cahoon
at [phone] or Ms. Dulcie Phillips [phone]
I certify, under penalty of law, that this document and all attachments were prepared
under my direction or supervision in accordance with a system designed to assure that
qualified personnel properly gather and evaluate the information submitted. Based on
my inquiry of the person or persons who manage the system, or those persons directly
responsible for gathering the information, the information I submitted is, to the best of my
knowledge and belief, true, accurate, and complete I am aware that there are significant
penalties for submitting false information, including the possibility of fines and
imprisonment for knowing violations
Progress Energy Carolinas, Inc
Mayo Steam Plant
10660 Boston Road
Roxboro NC 27574
Sincerely,
Robert E. Beasley - Manager
Mayo Electric Generating Plant
NOV 1 0 2005
f t1 S��

MAYO ELECTRIC GENERATING PLANT
DRAFT NPDES PERMIT COMMENTS
Cover Letter of Permit, the draft permit contains the following significant changes from
your current permit:
The first bullet states the following. "The following statement has been added to the
effluent limitations page for Outfall 001: Monitoring for total residual chlorine is
required only if chlorine based compound is added to the system". The plant request
clarification of the statement because free available chlorine is the limited parameter on
the effluent limitations page for Outfall 001.
• The plant would like to identify the newly created Internal Outfall 007 as either Internal
Outfall lA or Internal Outfall 008, to eliminate any possible confusion with storm water
Outfall 007, previously removed from the NPDES permit.
Cover Page of Permit
The Company should be identified as: Carolina Power and Light d/b/a Progress Energy
Carolinas, Inc instead of Progress Energy.
Supplement to Permit Cover Sheet
The Supplement to Permit Cover sheet should read ": Carolina Power and Light d/b/a
Progress Energy Carolinas, Inc." is hereby authorized to:
Item 1. on the Supplement to Permit Cover Sheet Cooling Tower System (Outfall 001)
should include only the sentence, Less than once per year the cooling towers and
circulating water system are drained by gravity and discharged directly to Mayo
Reservoir.
• Item 1. on the Supplement to Cover Sheet, Cooling Tower System (Outfall 001), states
the following, "Cooling Tower blowdown water is usually mixed with ash sluice water
prior to discharge to the ash pond." This sentence should be deleted, with the creation of
an internal outfall for cooling tower blowdown to the ash pond the cooling tower system
(Outfall 001) will not mix with ash sluice water prior to discharge.
Item 1 on the Supplement to Permit Cover Sheet should include a description of the
Internal outfall which should read, Cooling tower blowdown is directly discharged to the
ash pond via the ash pond treatment system Cooling tower blowdown is usually mixed
with ash sluice water prior to discharge to the ash pond. Cooling tower blowdown is
indirectly discharged to Mayo Reservoir via the ash pond treatment system (Outfall 002).

Item 1 on the Supplement to Permit Cover Sheet, Stormwater Discharge System
references Outfall 006, 006a, 006b, 006c, 006d, and 006e. It should read 006a, 006b,
006c, 006d, and 006e. There is not an outfall 006.
• Item 2. on the Supplement to permit cover sheet incorrectly classifies Mayo Reservoir as
a class C water. The correct classification is WS -V.
A. (1) Effluent Limitations and Monitoring Requirements
• Under effluent characteristics flow is to be sampled by pump logs, the plant requests that
be changes to pump logs or similar readings to be consistent with the Outfall 002
requirement.
A. (1) Note 1. Sample Locations: E — Effluent. States the following, "Samples taken in
compliance with the monitoring requirements listed above shall consist of cooling tower
blowdown after mixing with fly and bottom ash, but prior to discharging to the lake."
The plant requests the description read, "Samples taken in compliance with the
monitoring requirements listed above shall consist of cooling tower effluent prior to its
discharge to Mayo Reservoir."
A. (2) Effluent Limitations and Monitoring Requirements
Under effluent characteristics flow is to be sampled by pump logs, the plant requests that
be changes to pump logs or similar readings to be consistent with the Outfall 002
requirement
The last sentence on the page sates, the following: "This permit does not authorize a
discharge directly to the Mayo Reservoir." The plant requests the sentence be changed to
read the following: "This outfall is not authorized to discharge directly to the Mayo
Reservoir."
Section A.M. — Stormwater Monitoring Requirements / Qualitative Monitoring
• Because the permit does not require analytical monitoring, the first sentence in Notel
should be omitted and the second sentence in Note 1 changed to "Qualitative monitoring
will be performed twice per year, once in the spring (April — June) and once in the fall
(September — November)."
Section A.(10). — Stormwater Minimum Monitoring and Reporting Requirements
• The last sentence in b. States the following: "The initial visual monitoring event shall be
performed and simultaneously with the first analytical monitoring event and
documentation of only this initial visual monitoring event shall be submitted along with
the required analytical monitoring submittal." The plant request clarification of a

schedule to perform visual monitoring, since no requirement for analytical monitoring
exists in the permit.
• Because this permit does not require analytical monitoring and Section A. (10) c., d, and
e., reference analytical monitoring, the plant requests a sentence at the end of the section
stating the following: "No analytical monitoring is required by the permit."
• F. (2) states the following: "Foundation drains, air conditioner condensate without added
chemicals, springs, waterline and fire hydrant, water from footing drains, flows from
riparian habitat and wetlands, fire training and fire system testing." The plant requests
that wash down water be added to the list of discharges associated with industrial
activity.
Section A.(11). — Fish Tissue Sampling
• A. (11) states the following, "Progress Energy shall conduct fish tissue sampling for
Arsenic on an annual basis. The fish tissue sampling plan shall be approved by the
Division's Environmental Sciences Section prior to commencement of sampling. The
plant requests the Division review the requirement based on the following modeling
study conducted at the Mayo Plant by Progress Energy. A description of the study
follows:
Progress Energy performed a steady-state complete mix analysis for the volume of the Mayo
Plant ash pond discharge compared to the Mayo Reservoir volume available for dilution.
The analysis procedures are detailed in the EPA Technical Support Document for Water
Quality -based Toxics Control, Section 4.5 -Completely Mixed Discharge Receiving Water
Situations (USEPA 1991). The most conservative approach for the analysis was taken by
assuming there was no inflow from Mayo Creek and that the ash pond water could only mix
into the top 5 meters (i. e., epilimmon) of the reservoir. In reality, the reservoir is only
strongly stratified from during the summer months and the entire volume would be available
for dilution during the cooler months (following turnover and prior to stratification).
Additionally, the equations call for a first -order decay constant which assumes a decreasing
concentration of a substance of interest. In this case, we calculated the volume proportions
assuming constant volume proportions (K = 1). The analysis was performed using the
equations as follows:
T — V/Q � �,�... r� � � N j I �°`- i cam- �
A_
Com= C,,, /(1+ TwK) � t`J
Where: T,,, = mean hydraulic residence time
V = lake volume available at design conditions
Q = mean total inflow at design conditions
C = steady—state lake concentration (% IWC)
C,,, = steady—state inflow concentration (100% ash pond effluent)
K = first -order decay rate.

Completing the equations resulted in the following dilution factor (IWC):
and
TW =12,686 million gallons/8.14 million gallons/day
T,,, = 1558 days
C =100/(1+ 1558)
C = 0.06.
Thus the maximum steady-state complete mix ash pond proportion of the Mayo Plant ash
pond effluent in Mayo Reservoir is 0.06% IWC.