NC0025534_Wasteload Allocation_19820111

NPDES DOC /WENT SCANNING COVER SHEET
NC0025534
Hendersonville
WWTP
NPDES Permit:
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File
-Historical
Report
Speculative
Limits
Instream Assessment
(67b)
Environmental Assessment (EA)
Permit
History
Document Date:
January 11, 1982
Thus document in prizited on remise paper - ignore any
content on the reYerse side

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Facility Name:
Existing
Proposed
/I
NPDES WASTE LOAD ALLOCATION
, by/AfiTe, I vti X
Permit No • uc'90Z5534 Pipe No.:
Design Capacity (MGD):
Receiving Stream:
Reference USGS Quad.
. s
Industrial (% of Flow):
/ Cud Cre,t
00 1
"%4'
Date. Ill l f t'2
County • 1-4ftUY`
Domestic (% of Flow):
Class: Sub -Basin:
F c�z
(Please attach) Requestor• `S• Amu(-
H;
(Guideline limitations, if applicable, are to be listed on the back of this form.)
Regional Office n
Design Temp • a
7Q10:• Ye) C_
Location of D.O.minimum (miles
Velocity (fps): d • G
Drainage Area:
Avg. Streamflow: • /80 rt'S
Winter 7Q10: — 30Q2•
below outfall): S & Slope. 3, C
K1 (base e, per day, 200C) : 0►3 E K2 (base e, per day, 20°C) • 1, 7-0
Effluent
Characteristics
Monthly
Average
Comments
e01?
Sow 4-
Ts5
30"11,-
F Cal Ce�'
irn.
IOoo//ootJ.
n
f e
6-9set
Original Allocation
Revised Allocation
Effluent '
Characteristics
Monthly
Average
Comments
Date(s) of Revision(s)
(Please attach previous allocation)
repared By: YY161.4-1- ,
Reviewed By: Date:

Confirmation Only
REQUEST
*********************
FACILITY NAME
TYPE OF WASTE
COUNTY
REGIONAL OFFICE
RECEIVING STREAM
7010 : 40 CFS
DRAINAGE AREA
WASTELOAD ALLOCATION APPROVAL FORM
HENDERSONVILLE WWTP
HENDERSON
ASHEVILLE
MUD CREEK
W7010 :
98.00 SQ.MI.
CFS
*********************
REQUESTOR : S.ABDUL-HAOO
SUBBASIN : 04-03-02
3002 :-
STREAM CLASS :C
CFS
************************ RECOMMENDED EFFLUENT LIMITS ************************
WASTEFLOW(S)
BOD-5
NH3-N
D.O.
PH
FECAL COLIFORM
TSS
(MGD)
(MG/L) :
(MG/L)
(MG/L)
(SU) :
(/100ML):
(MG/L)
2.3
30
NR
NR
6-9
1000
30
o L'Pl/
********************************************************************************
FACILITY IS : PROPOSED ( ) EXISTING (V) NE ( )
LIMITS ARE : REVISION ( ) CONFIRMATION (.../) OF THOSE PREVIOUSLY ISSUED
REVIEWED AND RECOMMENDED BY:
MODELER
HEAD,TECHNICAL SERVICESttBRANCH
REGIONAL SUPERVIS0R'1M
PERMITS MANAGER
APPROVED BY :
DIVISION DIRECTOR
'ATE
_!DATE :_ F)-
DATE : _3
_tL
DATE : 41-1/1-2--

N.
Jospeh W. Grimsley, Secretary
Division of Environmental Management
September 17, 1981
MEMORANDUM
TO: Roy Davis, Regional Supervisor
Asheville Regional Office
FROM: Forrest Westall, Head
Monitoring & Technical
vices Branch
SUBJECT: Model Results: City of Hendersonville -
Mud Creek July 31, 1981
With the data you provided to our office in your August 6th memo, a
"Level B" analysis on the City of Hendersonville's discharge to Mud
Creek has been completed. Enclosed is a copy of the results of the model;
the results have also been forwarded to Robert Helms.
Enclosure
cc: ark Lewis

Impact Evaluation of the City of Hendersonville July 31, 1971 Discharge to Mud Creek
Background
A "Level B" analysis was performed on the City of Hendersonville's discharge
to Mud Creek. The water quality and flow parameters used as inputs for the model
were obtained from the City of Hendersonville by the Asheville Regional Office.
The data is from July 31, 1981. The only exception to this is the effluent NH3-N
data, measured on July 30. Also, no effluent D.O. value was available. As there
was no significant change in D.O. between the upstream and downstream stations,
the effluent D.O. was assumed to have the same value as the upstream stations.
Listed below are the water quality and flow values used in the model:
Wastewater Flow = 2.5 MGD
Effluent BOD5 = 31 mg/1
Effluent NH3-N = 5.88 mg/1
Effluent BODultimate* = 54.5 mg/1
Effluent D.O. = 6.9 mg/1
Upstream Flow = 30 cfs
D.O. Upstream = 6.9 mg/1
BODultimate Upstream = 2 mg/1
Temp. of Stream = 21°C
The Hendersonville WWTP discharges into Mud Creek just below its confluence
with Clear Creek. The drainage area at this point is 98 mi2 yielding an average
flow of 180 cfs and a 7Q10 flow of 40 cfs. The average velocity in Mud Creek for
an upstream flow of 30 cfs is estimated to be 0.47 ft/sec.
The attached graph shows the BODultimate decay and dissolved oxygen (D.0.)
profiles for Mud Creek below the Hendersonville discharge. As can be seen,
because of dilution, the wasteflow has little impact upon the D.O. resources of
the stream. The D.O. depression is less than 0.1 mg/1 below background and is
predicted to occur 1.4 miles below the outfall.
*BODultimate = BOD5 + 4 (NH3-N)

-2-
Approximately 2.2 miles below Hendersonville, Old Virginia, an industrial
discharger is permitted to release 0.04 MGD of industrial waste with a BODultimate
of 276 mg/1. This was included in the model and its effect can be seen in the
slight rise of the BODultimate profile. Old Virginia had no effect on the
projected D.O. profile of Mud Creek. The slight D.O. sag in Mud Creek, due to
the dischargers, returns to background levels approximately 4.4 miles below the
Hendersonville WWTP and remains at background as Mud Creek enters the Broad River,
6.1 miles below Hendersonville.
Discussion
Though the model predicts the Hendersonville discharge to have an insignificant
effect on water quality, it has been stated that the effluent on July 31 visually
appeared to be of poor quality. This would likely be due to suspended solids in
the effluent. Samples taken that day indicated suspended solids to be 28 mg/1
which is within limits prescribed by secondary treatment. However, it is possible
that, at times during the day, there were larger pulses of wasteflow that might
have caused sloughing off of bacterial film on the trickling filter media. This
material would be composed of biological solids. Much of these solids tend to
settle out slowly and thus might have not been removed in the final clarifier.
They would have ended up in the final effluent giving the effluent a poor visual
appearance.
It is important to note that we do not have a water quality limit for total
suspended solids. Limits for this parameter are based upon effluent guidelines
only. Also, there is really no effective way of modeling suspended solids. This
parameter does not directly affect the dissolved oxygen in the water column.
However, the solids will settle out along the stream bed below the discharge.
This deposition will affect the stream in two ways. First, the solids are
likely composed of organic matter and will start to decay in the stream bottom.
This decomposition will exert an oxygen demand on the dissolved oxygen resources
in the water column. This benthic demand is incorporated into our advanced
models when we cannot account for the oxygen demand from the organic material in

-3-
the water column alone. In a very slow moving shallow stream, the benthic demand
can be quite significant.
Secondly, deposition
the insect larvae that live
organisms rely on access to
and oxygen requirements. A
organisms and disrupt their
great reduction in both the
of suspended solids can have an adverse effect upon
on the stream bottom. Many of these benthic
the water column where they obtain both their nutritive
heavy solids deposition will cover the benthic
access to the overlying water. This can lead to a
population and diversity of the benthic community.
These organisms are important in that they serve as a food source for fish and
are thus a key element in the food chain of larger organisms.
Conclusions
In summary, from the data supplied by the City of Hendersonville, the
WWTP discharge did not have a significant effect upon the oxygen resources of
Mud Creek. However, there may have been episodes of high solids loadings from
the outfail. These solids can adversely affect Mud Creek by both contributing
to the benthic oxygen demand and by disrupting the availability of the water
column to the organisms living on the stream bottom.

HENDERSONVILLE WWTP-MUD CREEK
QW=2.5 MGD QS=30 CFS
Discharge Point
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0.3 0.9
r i i T 1 1 1 r .
1.5 2.1
Miles Below Discharge
r r 1 ..
2.7 3.3
DISSOLVED OXYGEN=DASHED LINE
BOD ULTIMATE=SOLID LINE
3.9 4.5

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