NC0031879_Report_19820601

Marion-Corpening Creek Study Plan
Catawba River Basin
June, 1982
Division of Environmental Management
Water Quality Section
Operations Branch
Monitoring and Technical Services 'Mit

I. Introduction
The City of Marion has requested that the Division of Environmental
Management review the effluent limits established for their Corpening
Creek WWTP. Of special concern is the phosphorus limitation placed on
this facility. Phosphorus limits were developed primarily as a product
of limited work by the U.S. Environmental Protection Agency in the head-
water lakes of the Catawba River. (Please see attached August 3, 1981
letter). This work was accomplished during 1973 and 1974. However,
major changes have occurred in the Lake Rhodhiss drainage area which
necessitates a re-evaluation of the impact of the Marion discharge.
Significant among these changes was the introduction of several new
domestic dischargers with design capacities greater than the Marion-
Corpening Creek WWTP. The Marion facility presently has a design capacity
of 3 MGD.
II. Lake Models
First, it would be of importance to ascertain the present loading of
phosphorus to Lake Rhodhiss and the percentage of this loading
contributed by Marion employing phosphorus removal. This would then be
compared to the projected loading to the lake assuming no phosphorus
removal by Marion. If a linear relationship is assumed between in -lake
phosphorus concentration and phosphorus loading then the effect on Lake
Rhodhiss of suspending Marion's phosphorus removal may be estimated.
The impact that the Marion-Corpening Creek WWTP has on eutrophication
in Lake Rhodhiss may also be analyzed by the use of several models. All
of these models involve the estimation of nutrient loadings into the
lake from both point sources and non -point source runoff.

One of these models is the loading model proposed by Vollenweider
(1975) where:
L (P) = 100 + 10Z
Tw
1000
L (P) = permissable phosphorus (P) loading rate (gmP/m2/yr)
Z = mean depth of the body water (m)
Tw = hydraulic residence time (yr)
The permissable P loading reate indicates the maximum P loading
level that a given water body can tolerate and still retain its
oligotrophic or mesotrophic status. Vollenweider based most of his
work on data from Canadian and Swiss lakes. In order to account for
conditions in southeastern lakes and reservoirs which differ greatly from
the lakes studied by Vollenweider, Marlar and Kutzman (1980) have proposed
a refinement of the Vollenweider model. Marlar and Kutzman suggest
computing the ratio of the actual P loading rate to the Vollenweider
predicted dangerous P loading rate for the lake in question and for all
lakes in the same region or area. The resulting dimensionless number
can then be used to define that breakpoint for all lakes in the region
at which higher values can be considered as predicting a eutrophic
condition. This technique was used by EPA Region IV in their analysis
of TVA reservoirs (EPA, 1980).
Vollenweider (1976) also developed an approach for predicting an
in -lake P concentration based on the actual P loading rate as follows:
CP lake] = L (P)/qs
1 + (Tw)1/2
Where: [P lake] = in lake P level (ug/1)
L (P) = actual P loading rate (mgP/m2/yr)
qs = aereal water load = Z/Tw (m/yr)
Tw = hydraulic residence time (yr)
Z = mean depth (m)

This approach was assessed and found to be satisfactory predictor of
actual in -lake phosphorus levels in five TVA reservoirs (EPA 1980).
Vollenweider's predicted in -lake phosphorus concentrations were adjusted
for actual in -lake phosphorus levels. By the use of a regression
equation the adjusted in -lake phosphorus concentration was then used to
predicte summer mean chlorophyll a concentrations.
Vollenweider's models have been developed using data taken largely
from natural lakes where completely mixed conditions are assumed. In
impoundments, which tend to have hydrologic and morphologic characteristics
which are
gradients
very different from natural lakes , significant longitudinal
often exist. The empirical constants developed for natural
lakes may not be applicable to impoundments.
Higgins and Kim (1981)
have presented a plug flow model for lakes and reservoirs which have
significant longitudinal variation in phosphorus
concentration at any point x along the reservoir
phosphorus concentration at the inlet as well as
between zero and x:
Cx = Ci e ( - a )
concentration. Phosphorus
is a function of the
the residence time
Where: Cx = phosphorus concentration at mile x
Ci = phosphorus concentration at mile 0
which corresponds to lake inlet
a = phosphorus sedimentation coefficient (an
empirical constant)
Tx = residence time between milepoint 0 and milepoint
x
Lake Rhodhiss is an impoundment which exhibits significant longitudinal
variation (Anne'Witzig, personal communication).
(1981) model should be applicable to this lake.
Thus Higgins and Kim' s
It should be noted that the above models all assume that the lake
is phosphorus limited. Previous algal assay work had indicated the lake
to be nitrogen limited; however in -lake data has shown that nutrient
limitation vascillates between nitrogen and phosphorus depending on
station and time of year (EPA, 1975).

Algal nitrogen requirements are related to phosphorus requirements
by a ratio of 15:1 by weight (Vollenweider, 1977). Therefore the
phosphorus loading rates distinguishing the various trophic states
(oligotrophic, mesotrophic, eutrophic) may be multiplied by a factor of
15 to obtain the corresponding nitrogen loading rates in a nitrogen
limited environment.
III. Trophic State
In order to determine the necessity of requiring phosphorus removal
for Lake Rhodhiss, a comparison of trophic state with and without phosphorus
removal should be made. Using Marlar and Kutzman's (1980) refinement
of the Vollenweider loading model, it can be determined whether or not
a change in trophic state can be expected from allowing Marion to
discontinue phosphorus removal.
Using both Vollenweider's (1976) and Higgins and Kim's (1981) models
average phosphorus concentrations may be estimated for Lake Rhodhiss both
with and without phosphorus removal at the Marion Plant. These concentrations
may then be used in the total phosphorus trophic state index (TSI)
developed by Carlson (1977) whereby:
TSI(TP) = 14.42 In TP + 4.15
The resulting dimensionless numbers may then be compared.
Furthermore, it may be possible, using previous lake data, to develop
a regression equation relating chlorophyll a concentrations to in -lake
phosphorus concentrations. If this can be done, calculated phosphorus
concentrations can then also be used to predict chlorophyll a concentrations.
These chlorophyll a values can then also be inputted to another of Carlson's
(1977) TSI equations.whereby:
TSI (chlorophyll) = 9.81 In chla + 30.6
The resulting TSI values under the different phosphorus removal regimes
may then be compared.

IV. Existing Data Base
The North Carolina ambient water quality network has stations which
will help in the estimation of nutrient loadings entering Lake Rhodhiss
from the Catawba River and major tributaries. In December, 1982, in order
to facilitate the Lake Rhodhiss study the nutrient sampling frequency was
increased on two existing ambient monitoring sites while three old
secondary sites were reactivated. Sampling frequency was increased to
monthly on these ambient stations. Table 1 lists the available data
from these five stations as well as three other major ambient stations.
The study area and the locations of these stations are indicated in Figure
1. Additional ambient monitoring data exists as well.
USGS has estimates for average flow on all major tributaries entering
Lake Rhodhiss. Daily flow records are available for the Catawba River
near Marion and Lower Creek near Lenoir. It may thus be possible to
extrapolate these records to the points where these tributaries enter Lake
Rhodhiss and obtain flow weighted averages of nutrient concentrations.
Where water quality data is lacking loading estimates may be made from
existing land use patterns using literature values.
Inputs from point sources may be estimated using monthly self -monitoring
data. The monthly self -monitoring reports provide accurate data of daily
flow. However, except for the Marion WWTP, no other dischargers monitor
for phosphorus. In December 1981
Regional Office collect a 24-hour
for all dischargers with a design
Rhodhiss drainage area. This was
V. Field Work
it was requested that the Mooresville
composite sample for nutrient analysis
flow above 0:5 MGD entering the Lake
to be taken by March 31, 1982.
The Technical Services Unit is proposing to do additional field
work on Lake Rhodhiss as well as on point and non -point sources entering
its drainage area. This work is tentatively scheduled for late July 1982.

The field work will include an accurate depth profile of the lake.
Depth soundings will be taken on numerous cross -sections as well
as in the center channel along the entire length of the lake.
A reliable estimate of depth is essential for all lake models.
Significant sedimentation has likely occurred since the lake was filled.
In order to obtain additional information on loading. nutrient grab
samples will be taken on all the major tributaries to Lake Rhodhiss. The
tributary stations are listed in Table 2. The locations of these stations
are shown in Figure 2.
It is also desired to see how nutrients and chlorophyll a change
longitudinally along the lake. Seven stations were chosen along the
length of the lake in the center of the channel. Two sets of nutrient
series will be taken at each station; one set will be an integrated sample
from the euphotic zone, while the other will be taken from the hypolimnion.
An integrated sample for chlorophyll a will be taken from the euphotic zone
as well. D.O. and secchi disk depth will also be taken at each station.
These stations are listed in Table 3 and their locations are indicated in
Figure 3.
Limited nutrient data is available for the dischargers entering the
Lake Rhodhiss draiange area. As discussed previously. twenty-four hour
composite samples for nutrients are being taken by the Regional Office on
the eight dischargers with a design flow equal to or greater than 0.5 MGD.
During the field survey, personnel from the Division will
take grab samples for nutrient analysis from the same eight dischargers
as well. These dischargers with their respective design flows are listed
in Table 4. Their locations are shown in Figure 4. While still a limited
data base, the grab samples will assist in giving a range of variability
for effluent values. If the required monitoring equipment is available,
24-hour composite samples will be taken from the larger dischargers.
In order to determine the limiting nutrient. it is also desired that
algal assays be done on Lake Rhodhiss. The format for this work will be
established in conjunction with Ron Raschke at EPA in Athens, Georgia.

VI. Completion of Modeling Work
It is expected that a preliminary analysis of the data utilizing
the previously described lake models will be completed by mid October,
1982.

Table 1
Major Ambient Monitoring Stations
Storet # Location
CTB028A Catawba R. @ SR 1147
Glen Alpine
CTB029 Silver Cr. @ 70W
C1250000
Catawba R. @ Morganton
CTB031-01 Johns R. @ SR 1438
Oak Hill
CTB032 Lower Cr. @ Hwy 321
CTB034 lA Lower Cr. @ SR 1501 nr
Morganton
Data
Available Period of Record
N + P, D.O. 740521-790828
811207-present*
811207-present*
750513-770126
770126-810225
750521-761129
770126-771027
771027-820405*
750529-770126
770126-810211
750521-770126
770126-820405*
CTB034A L. Rhodhiss @ SR 1501 nr N + P, D.O. 740604-820330
Drexel Secchi
CTB040A
Lake Rhodhiss @ SR 1001
near Baton
*active
730329-810803
8112.07-present*
Sampling
Frequency
"every 3 mo
monthly
monthly
every 3-4 mo
every 1-2 mo
"'every 4 mo
every 2 mo
almost monthly
"'every 4 mo
every 1-2 mo
"'every 4 mo
every 1-2 mo
yearly
occasionally
more often
yearly or more
often
monthly

r
,.I
•
ti
C
ua
—J
v
•, I
›-
CD
':.
l
r
•
•
Figure I
Major_Ambient Monitoring
Stations
M��aw4lt

Stream
Table 2. Stream Stations
Location Station #
Muddy Creek Hwy. 70 S1
Silver Creek (CTB029) Hwy 70W S2
Warrior Fork SR 1440 S3
Johns River (CTB031-D1) SR 1438 S4
Lower Creek (CTB034-1A) SR 1501 S5
Catawba River (CTB028 A) SR 1147 S6
Catawba River NC 18 S7
Parametric Coverage: Nitrogen and Phosphorus series should be
taken at the above stations.

0
W
J
•J
•
y
1 •
,;f _ \l
•
.yy
j) ii_ i_J• h
t.
\
•
173.
�• ,J
g
CC
-
L
•
ac 1 ' ; r
1 i .� /, Figure 2
Li l
z \; Stream Stations
\\
it
'.. .
•'rill/
•
)
\,\
) • ' ▪ •'>•)
l

Table 3. Lake Stations - Lake Rhodhiss
Station # Location
L1 (CTB034A) at SR 1501
L2 near mouth of Smoky Creek
L3 by island just below mouth of Howard Creek
L4 (CTB040A) SR 1001
LS by boat ramp just beyond mouth of Freemason Creek
L6 where lake turns sharply to right below mouth of
Hayes Mill Creek.
L7 just above Rhodhiss Dam
Parametric Coverage: Sampling will be performed at the center
of the channel. Secchi disk depth and D.O. will be taken at each
station such that the euphotic zone and hypolimnion may be determined.
An integrated sample will be taken from the euphotic zone for analysis
of N and P series and chlorophyll a. A sample for N + P series will
also be taken from the hypolimnion.

tf?l`!UP: •'
ccoz
G1yJ``,\ ` 0J .v \t\
? ,,.I- :% l;1�•
Figure 3
1 ' ' �' .�... •_ r ;� i ` Lake Stations
Y.), \\\.)
t) - �/ St'_---',- -< J
ii.mf //tr,/t• + ��,� ,ter-J � / - oJ
;f �� l��YJ Q i�y°
N....`'.ter
•
~I�
1 a /�•.,
--
�� !",✓mil I. .`
_ t i ,,f i
l
-L`
F—
s. '.. LW 1f
CC
,�� .�� � -
0� _,
•
• • 1
J
O `
Z
1
U.) C't
II H..11'11 a
it
Free m a 'II
r) //0 . � �1 tit
1 ,
: 1
('
/
i
r

Table 4. Major* Dischargers in Lake Rhodhiss Drainage Area
Discharger Design Flow
1. Morganton -Catawba River WWTP NC0026573 8.0 MGD
2. Valdese -Lake Rhodhiss WWTP NC0041696 7.5 MGD
3. Lenoir -Lower Creek WWTP NC0023981 6.0 MGD
4. Valdese-McGalliard Creek WWTP NC0020753 3.2 MGD
5. Marion-Corpening Creek WWTP NC0031879 3.0 MGD
6. Great Lakes Carbon -Silver Creek NC0005258 2.6 MGD
7. Valdese -Hoyle Creek WWTP NC0021199 1.0 MGD
8. Drexel WWTP-Howard Creek NC0021296 0.5 MGD
*This list includes all dischargers.with a design flow
equal to or greater than 0.5 MGD.
Parametric Coverage: Grab samples for N and P series will be taken
from the above dischargers. If required monitoring equipment is available,
composite samples will be taken at the larger dischargers.

\
r=
CSS
t�Irlit') �U"
.11
Y
1 �r
Figure 4
Major Dischargers in Lake Rhodhiss
Drainage Area
•1,94
. -Jo
\LaJ
Q \,11i, .....
fir ] ly
\CC `J 1,Q
rt
•
c9

.CC
)
`
Figure 4 Cont'd
•
• `
0
Li
I.11lit'
•
nut 1.
1k
03 il2.704.31
�_
(•►
/r// )/
l•
Cr—IC:2 a
dim
tot I`v
/? /
( )J
`8104, 011 _
03 113 G1,--3-_
Q� I
NC
fro i
CU
•,J \
/tlair (/ r-1
ra
tl-
r('('1%ii�.\Ilii
r
•
1 `
•
Ifi
t3
r3
l,cr'
—t.1
1 it/(l1•'r, 14t:
1►
i + ;�/•
•
a
•

REFERENCE CITED
Carlson, R.E., "A Trophic State Index for Lakes", Limnol. Oceanogr. Vol.
22:361-369, 1977.
EPA, "Report on Rhodhiss Lake, Burke and Caldwell Counties, North Carolina",
EPA Region IV, National Eutrophication Survey, Working Paper No.
388, June, 1975.
EPA, "Eutrophication Analysis of the Proposed Columbia Reservoir - Duck
River Basin, Tennessee", Water Qaulity Standards Section, Water
Quality Management Branch, Water Division, EPA -Region IV, July
30, 1980.
Higgins, J.M. and Kim, B.R., "Phosphorus Retention Models for Tennessee
Valley Authority Reservoirs", Water Resources Research, Vol. 17,
No. 3: 571-576, 1981.
Marler, J. and Kutzman, J'., "A Holistic Lake System Assessment", A Paper
presented at the National Water Quality Management Conference,
Atlanta, Georgia, June 4-6, 1980.
Vollenweider, R., "Input - Output Models, with Special Reference to the
Phosphorus Loading Concept in Limnology", Schweiz. Z. Hydrol.,
Vol. 33:53-83, 1976.
Vollenweider, R., Personal Communication found in Rast, W. and Lee, G.,
"Summary Analysis of the North American (US Portion) OECD
Eutrophication Project: Nutrient Loading - Lake Response
Relationships and Trophic State Indices", U.S. EPS Ecological
Research Series, January, 1978, EPA-600/3-78-008, communication
transmitted January 20, 1977.

DIVISION OF EMMENTAL MANAGEMENT
August 3e 1981
Mr. Howard Ze1 lery Acting Director
Enforcement Division
U. S. Environmental Protection icy
Region Iv
345 Cot rtland Strut, N.E.
At1 an to s Georgia 35365
Subject: 'i•: i uesi-fer...Nedi fication
�„,, 44. �� Dischar Permit'
Carpeting Creek Wastewater Treatment
•' Plant
City of Marlon 1
licDwell CotaiQy s North Cat i na
Dear Mr. . Zeller:
The City of Marion has rutted that -Division of Envi ron:r tal
t review the effittent limits contained as a part of tones mi-
t:harp Permit Colo. PIC0031879 to determine if the . lintitations placed upon
phosphons and oxygen consuming waste are valid in -11 girt of present day
standards and allocation methodology.
Limitations for oxygen consv1ng taste were the result of a modified
Level it evaluation waning limited field work specific to C rpening Cry
was utilized for purposes of developing constants for use in the modified
Streeter -Phelps Equation. P osphor= l imi is were ,,', velopad pri sari ly a
a pr 3dtct of limited work by the!:o S. Envi ron ental Protection Agency
t n the headwater lakes of the Catawba River. The City of itsrion ha$ ex-
pound interest in gaining sow relief from pint final effluent limns
for the reason that tva experience City might thereby experiensavil ;, in opera-
tional
costs at its Coriling Creek Wastarater Treatment Plant.
The Division of En vi tal Manegemant is i h 1 n g to inert time in
saking the doter nation as to whether conditions as they exist today in
Lake Rhodi ss or as they exist in the near future raight al l aw nods fi ca-
tion of the phosphors limits for the C orrpening Comic Wastewater Treatment
Plante Addltlonallya the Division of Environmental f nt is willing
to invest its mammas in the conduct of a Laval C sty of Corpen1ng C:,s f `�
Creek which would include In intensive spy with slug sapling tor �.
mina if the present permit limits for o,ypn consuming avast .are in ...,:_ ,S
i.; .
of modification. Obvilys the inmost of time and ray in
effort by the Division Of FAVimmental itnagacesst mold not be 3. , fib'- ",, �.
if the U. S. Environmental Protection Agency would not allow role
certain 1irdts should the above scribed star demonstrate that
Quality Standards would be protected in Corpon1ng Creek by the disci` r y 6.„ „ •
wastewater of a lesser -quality then presently described .in the City -11P ES

. Ord Zeller
Page 2
August 31, 1981
Permit. Cbviauslyo effluent lints could be no less stringent the quh d
by applicable effluent guidelines. The State of North Carolina would be in-
terested in giving this relief to the City of Harlon if justified so that
the City 10 turn et ght be in a position to experience cost savings as a
re-
sult of Tess stringent effluent requirements.
I would appraciate your giving this
Should 1t be helpful to you 1n arriving
pose' further0 please contact Kr. L. P.
Section at 919-7. 3 c 5083.
cc: Vit. L. P. Banton 0 Jr. a Chief
Water Quality Secct1 cat
Mr. J. Earl Daniels:, Manager
C1 Qy of fir! ae
matter your careful consideration.
at a decision to discuss this pro -
Benton:, Chief of the war Qual 1 ty
Sincerely yourss9
Original Signed By
POB€RT F. HELMS
Robert F. Wel =
81 rear
Kr. Heath P. Dobsa 9 Regional Engineer
Water Quality Section a Asheville
\iv)