NC0038377_Memorandum_19970114

DIVISION OF WATER QUALITY
January 14, 1997
MEMORANDUM
TO:
FROM:
Modelers
Jeff Myhra9M
DATE:
January 14, 1997
SUBJECT:
CP&L Mayo outfall descriptions
There are currently two permitted discharge points at the facility (outfall 001 and outfall
002). In addition, four outfalls (outfalls 004, 005, 006a, b,c,d,e, and 007a, b) were established to
monitor facility stormwater flow. The following is a description of each outfall at the CP&L Mayo
facility (See the attached map for outfall locations:
Outfall 001: Cooling tower blowdown. This water is usually directly
mixed with the ash sluice water. Occasionally (once per year maximum (if ever))
it is not mixed with bottom and fly ash and is discharged directly into the ash
pond. Heat exchanger water (low volume waste) is almost continuously
discharged out 001. Approximately once every two years the cooling towers are
drained completely for maintenance. This discharge goes directly to the Mayo
Reservoir. The established permit limits still have to be met with this discharge
(see attached flow chart for further clarification).
Outfall 002: The ash pond receives ash transport water, coal pile runoff,
stormwater runoff, cooling tower blowdown, and various low-volume wastes
such as boiler blowdown, oily waste treatment, wastes/backwash from the water
treatment processes, plant area wash down water, and equipment heat exchanger
water. The sewage treatment plant effluent is also routed to the ash pond.
Outfall 003: Domestic sewage use to discharge here. It now discharges
into the ash pond.
Outfall 004: Drainage from outside storage area.
Outfall 005: Drainage from the industrial area and oil/gas storage area.
Outfall 006a,b,c.d,e: Drainage from chemical feed building and cooling
tower area.
Outfall 007a.b:
Drainage from railroad area.
The facility currently has a daily maximum limit of 3.8 lbs/day for selenium. Apparently
during the last renewal, CP&L questioned Se as a daily maximum limit. The old model run
for Se in Mayo used the 5 µg/1 criteria under design conditions. Therefore, the daily
maximum limit is appropriate. This information is just a FYI .... I think CP&L will closely
scrutinize the Se limit during this renewal.
Special condition, Part III, Condition H - Condition to properly maintain domestic plant to
secondary standards was included in last renewal.

16 Outfall 002
Evaporation 11 Coo'lingTow'ersoutfall oo1 Mayo Reservoir
14
14
Misc. Equipment
Heat Exchangers
alternate
.........................
1
Ash Sluice Water Condensers
/ -'Y-'Y-
12
Fo
er & Turbine
9
Cumd Oo 1
/ x Ash Pond
-'t, Once p -lea,- (:-Feu
iS cli3'cGe c- e c✓ ally �
15
Coal Pile Runoff
6" T1 ask
J
7y -,;J d iCk.j c1
9 Intake Structure 3 s
Raw Water
Treatment
4
Potable &
Sanitary Syste
Fire ProtectionI I I Water Storage I Sewage
Treatment
Condensate I I I I Oily Waste
Storage j�� Ion Exchange Treatment
Misc. Low
Volume
Carolina Power & Light Company
Mayo Steam Electric Plant
Person County, N. C.
Schematic of Water Flow
Page 1 of 2 November 1996
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