NC0039578_SPECULATIVE LIMITS_20020729

NPDES DOCUWENT SCANNINO COVER SHEET
NPDES Permit:
NC0039578
TWSA WWTP #1
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Speculative Limits
Instream Assessment (67b)
Environmental Assessment (EA)
Permit
History
Document Date:
July 29, 2002
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State of North Carolina
Department of Environment
and Natural Resources
Division of Water Quality
Michael F. Easley, Governor
William G. Ross, Jr., Secretary
Alan W. Klimek, P.E., Director
July 29, 2002
Mr. Stan Bryson
Tuckaseigee Water and Sewer Authority
32 Asheville H ghway
P.O. Box•1051
Sylva, North Carolina 28779
1
NCDENR
Subject: Speculative Effluent Limits
TWSA Plant #1
Jackson County
Dear Mr. Bryson:
This letter is in response to your request for speculative eftluenrfimits for expanded discharges at.the
Tuckaseigee Water and Sewer Authority's Jackson County WWTP (NC0039578). The Division of Water Quality
(Division) has prepared a response to your request for speculative limits at 3.0 MGD at this plant.
The speculative limits were developed based on our understanding of the proposal, in addition to out
understanding of present environmental conditions at the proposed discharge location. The Division can not
guarantee that an NPDES permit will be issued at the proposed location. Final decisions can only be made after the
Division receives and evaluates a formal permit application for the proposed discharge.
In accordance with the North Carolina General Statues, the practicable waste treatment and disposal
alternative with the least adverse impact on the environment is required to be implemented. Therefore, prior to
submittal of an NPDES application, a detailed alternatives analysis must be prepared to assure that the
environmentally sound alternative was selected from the reasonable cost effective options. Attached is a guidance
document that will assist you or your consultant in preparing an engineering alternatives analysis. Please be certain
that sufficient documentation demonstrating the need for the additional flow is provided. In addition, if the
proposed expansion will use public monies, such an upgrade would have to undergo the State Environmental Policy
Act (SEPA) process. You are encouraged to contact the Division's SEPA contact, J. Todd Kennedy at (919) 733-
5083 ext. 555 prior to beginning plans for expansion.
Based on the available information, tentative limits for the proposed discharge to the Tuckasegee River 3.0
MGD for the Jackson County WWTP are attached. The limits are based on streamflows calculated based upon
regional equations fisted in the USGS document Low Flow Characienrticr of Streams in North Carolina. The following
flow calculations were made:
Receiving Stream
Tuckase ee River
Average Flow
635 cfs
Summer 7 to
149.6 cfs
Winter 7 io
184.1 cfs
The above flow information is somewhat lower than the previous flow estimates for the receiving stream
on which your current permit limits are based. You may wish to contact the USGS to obtain a new flow estimate
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 50 % recycled / 10 % post -consumer paper

for the Tuckasegee River. Please call Mr. Curtis Weaver of USGS at [phone] if you would like to pursue this
option.
This information was used in conjunction with the proposed effluent characteristics to develop tentative
limits. Please be advised that the limits and monitoring frequencies below were based on the information presented
in the speculative limits request. A complete evaluation of these limits and monitoring frequencies in addition to
monitoring requirements for metals and other toxicants will be addressed upon receipt of a formal NPDES permit
application.
A water quality model of the proposed discharge indicated that it would not cause a violation of the
instream dissolved oxygen standard of 6 mg/L given the effluent limits below. Please note that the following are
monthly average Htnits for the effluent characteristics fisted:
TWSA Plant #1
(Jackson
Flow
3.0 MGD
BODe
30 mg/L
Total Suspended Residue
30 mg/L
Dissolved Oxygen
Monitor only
NH3-N
Monitor only
Total Residual Chlorine
17 µg/L
Fecal Coliform
200/ 100 mL
Should you have any questions or if you need any additional information, please feel free to contact Natalie
Sierra at [phone], extension 551.
Sincer ly,
David A. Goodeicl��
Supervisor, NPDES Unit
cc: Asheville Regional Office
Central Files
CNPDES Unit Files:
Callie Dobson, Planning Branch
Kurt Wright, PE: W.K. Dickson & Company, Inc.
1200 Ridgefield Road
Suite 180
Asheville, North Carolina 28806

WK
OICKSON
Engineers . Planners . Surveyors
LandscapeArchitects
May 13, 2002
Mr. Dave Goodrich, Supervisor
NPDES Unit
NCDENR/DWQ
1617 Mail Service Center
Raleigh, NC 27699-1617
RE: Waste -Load Allocation Request for the
Tuckaseigee Water and Sewer Authority
Wastewater Treatment Plant Expansion
WKD #20071.00.AV
Jackson County, North Carolina
Dear Mr. Goodrich:
0�[�7�j n
MAY 16 2002 I �1
Po—. lia Stj.%E Eiioii+^,R I
We are working with the Tuckaseigee Water and Sewer Authority to expand their
existing wastewater treatment plant capacity from 1.5 MGD to 3.0 MGD. The
effluent is discharged into the Tuckaseigee River, approximately 1.5 miles south
of Dillsboro, as shown in the attached figure. The facility operates under the
NPDES permit number NC0039578.
We are requesting speculative limits and monitoring requirements for the
expansion so that we may complete the alternatives analysis for this project.
If you have any questions, or require additional information, do not hesitate to
call.
Sincerely,
W. K. Dickson & Comp/any, Inc.
�� `l�V
Kurt Wright, PE
�
Enclosures
cc: File, Jerry King
1200 Ridgefield Blvd.
Suite 180
Asheville, NC 28806
828.667.3925
Fax [phone]
wwvwkdickson.com
Other Offices
Atlanta. GA
Charlotte. NC
Columbia, SC
Hickory, NC
Raleigh, NC
Wilmington, NC

MODELING NOTES FOR SPECULATIVE LIMITS REQUEST
TWSA PLANT #1-JACKSON COUNTY WWTP
The Tuckaseigee Water and Sewer Authority (TWSA) has requested speculative limits for its
Jackson County WWTP, currently permitted at 1.5 MGD. The spec request is for 3.0 MGD.
Jackie Nowell last modeled this facility in 1987. Estimated summer 7Q10 at that time was 165
cfs and winter 7Q 10 was 199 cfs.
Using data from USGS Station Number 351050000 (Tuckasegee River at Dillsboro), which is
downstream of the discharge, and a mean annual runoff of 2.22, 1 obtained the following flow
estimates:
Summer 7Q10: 149.55 cfs
Winter 7Q10: 184.08 cfs
30Q2: 273.94 cfs
Qaverage: 635 cfs
The drainage area used was 286.00 square miles.
The above flow values are slightly lower than the flows currently on record (used in the
determination of the active permit's limits), so it may be appropriate to include a request that the
Permittee obtain updated flows from USGS for the discharge point.
The Level B model inputs were very similar to those used by Jackie Nowell in 1987, as follows:
Qd = 3.0 MGD
Drainage Area = 286 mil
Slope = 3 feet per mile
Length = 1.4 mi.
Qa r = 635 cfs
S7Q10= 149.6 cfs
W7Q10= 184.1 cfs
30Q2 = 273.9 cfs
Qarunoff = 0
S7Q 10runoff =0,= W7Q l0runoff
1 Reach
CBOD = 45 mg/L
NBOD = 90 mg/L
No DO limit
D.O. stream standard = 6.0 mg/L (trout waters)
The minimum D.O.-was 7.49 mg/L at the outfall. The D.O. recovered to 7.51 mg/L by the end of
the model run. The end CBOD was 3.21 mg/L and the end NBOD was 3.53 mg/L. Since a
tributary comes in just downstream of where the model ends, it is assumed that this will provide
sufficient dilution to return the CBOD and NBOD to ambient levels (i.e. secondary limits are
sufficiently protective).

SUMMER
---------- MODEL RESULTS -
Discharger : TWSA - JACKSON COUNTY WWTP
Receiving Stream : TUCKASEGEE RIVER
--------------- --
The End D.O. is 7.51 mg/l.
The End CBOD is 3.21 mg/l.
The End NBOD is 3.53 mg/l.
----------------------------------------------------------------------
WLA WLA
DO Min CBOD NBOD
(mg/1) Milepoint Reach # (mg/1) (mg/1)
---------------------- ---- ----
Segment 1 7.49 0.00 1
Reach 1 45.00 90.00
WLA
DO Waste Flow
(mg/1) (mgd)
0.00 3.00000

*** MODEL SUMMARY DATA ***
Discharger TWSA - JACKSON COUNTY WWTPSubbasin : 040402
Receiving Stream TUCKASEGEE RIVER Stream Class: C - TROUT
Summer 7Q10 149.55 Winter 7Q10 : 184.08
Design Temperature: 23.0
LENGTHI SLOPEI VELOCITY DEPTH Kd Kd Ka Ka KN
mile I ft/mij fps ft design 020° design @20° design
----------------- --------------------------------------------------------------
Segment 1 1.40 3.00 0.780 3.63 0.26 0.22 2.20 1 2.06 0.38
Reach 1
--------------------------------------------------------------------------------
Flow
CBOD
NBOD
D.O.
cfs
mg/l
mg/l
mg/l
Segment 1
Reach 1
Waste
4.650
45.000
90.000
0.000
Headwaters
149.550
2.000
1.000
7.720
Tributary
0.000
2.000
1.000
7.720
* Runoff
0.000
2.000
1.000
7.720
* Runoff flow is in cfs/mile

SUMMER
Seg #
Reach #
Seg Mi
D.O.
CBOD
NBOD
Flow
1
1
0.00
7.49
3.30
3.68
154.20
1
1
0.10
7.49
3.29
3.67
154.20
1
1
0.20
7.49
3.28
3.66
154.20
1
1
0.30
7.49
3.28
3.65
154.20
1
1
0.40
7.49
3.27
3.64
154.20
1
1
0.50
7.49
3.26
3.63
154.20
1
1
0.60
7.50
3.26
3.62
154.20
1
1
0.70
7.50
3.25
3.61
154.20
1
1
0.80
7.50
3.24
3.60
154.20
1
1
0.90
7.50
3.24
3.59
154.20
1
1
1.00
7.50
3.23
3.58
154.20
1
1
1.10
7.50
3.22
3.57
154.20
1
1
1.20
7.50
3.22
3.56
154.20
1
1
1.30
7.51
3.21
3.54
154.20
1
1
1.40
7.51
3.21
3.53
154.20
Seg #
Reach #
Seg Mi
D.O.
CBOD
NBOD
Flow

Facility: TWSA #1
NPDES#: NC0034268
Receiving Stream: tuckasegee river
Comment(s):
Low Flow Record Station Number:
Hydrologic Area Number:
Drainage Area Low Flow Record Station:
Qave Low Flow Record Station:
s7Q10 Low Flow Record Station:
w7Q10 Low Flow Record Station:
30Q2 Low Flow Record Station:
yayc
03.5105.0000
HA10
347
763.40 cfs
198.00 cfs
236.00 cfs
353.00 cfs
must be < 400 sq. miles
Drainage Area New Site: 286.00 sq. miles
MAR New Site: 2.22
Cave per Report Equation: 635 cfs
s7Q10 per Report Equation: (/104.97 cfs /
w7Q10 per Report Equation: \-150.00 cfs'
30Q2 per Report Equation: 218.41 cfs
Continue
Drainage Area Ratio:
0.82 : 1
[ new DA / Da at gage
Continue
Weighted Ratio:
0.77: 1
Over -ride Inappropriate Site ( y ):
Drainage Area New Site: 286.00 miles squared
11
MAR
New Site:
2.22
Weighted Qave per Report
Equation:
635 cfs
Weighted s7Q10 per Report
Equation:
w7Q10 per Report
Equation:
[=149.55Weighted
Weighted 3002 per Report
Equation:
273.94 cfs

Level B Model -- Data Input Record
NPDES Unit -- Date: 6/26/02 N. Sierra
GENERAL INFORMATION
Facility Name
TSWA #1
NPDES No.
NC0039578
Type of Waste
Domestic
Facility Status
Renewal
Receiving Stream
Tuckase ee River
Subbasin
4/4/02
County
Jackson
Regional Office
JARO
To o Quad
I F6SW/S Iva South
FLOW INFORMATION':
USGS Station Number
351050000 Tuckase ee River at Dillsboro downstream of disch
Date of Flow Estimate / Record
1935-1981
Drainage, Sq Mi
286
s7Q10 cfs
149.6
w7Q10 cfs
184.1
Ave Flow cfs
635
30Q2 (cfs)
274
MODEL INPUT INFORMATION
WASTE PARAMETERS
Speculative Flow (MGD)
3 MGD
MGD
Season
Summer
Winter
Summer
Winter
Summer
Winter
CBOD m /L
45.0
NBOD m /L
90.0
D.O. m /L
SEGMENTS AND REACHES R1 R2
Reach Length (mi)
1.35
Incremental Length mi
0.1
RUNOFF CHARCTERISTICS R1 R2
7010 cfs/mi
0
QA cfs/mi
0.0
CBOD m /L
2.0
NBOD m /L
1.0
D.O. m /L
TRIBUTRY CHARAT.ERISTICS R1 R2
7Q10 cfs)
CA cfs
CBOD m /L
NBOD m /L
D.O. m /L
Slope (ft/mi)
Comments: Level B Model File Names -- twsa

IWC Calculations
TWSA Plant #1 Proposed Expansion
Prepared By: Natalie Sierra, NPDES Unit
Enter Design Flow (MGD): 3
Enter s7Q10(cfs): 149.6
Enter w7010 cfs : 184.1
Residual Chlorine
Ammonia (NH3 as N)
(summer)
7Q10 (CFS)
0.05
7Q10 (CFS)
149.6
DESIGN FLOW (MGD)
0.011
DESIGN FLOW (MGD)
3
DESIGN FLOW (CFS)
0.01705
DESIGN FLOW (CFS)
4.65
STREAM STD (UG/L)
17.0
STREAM STD (MG/L)
1.0
UPS BACKGROUND LEVEL (1
0
UPS BACKGROUND LEVEL
0.22
IWC (%)
25.43
IWC (%)
3.01
Allowable Conc. (ug/1)
67
Allowable Conc. (mg/1)
26.1
Ammonia (NH3 as N)
(winter)
7Q10 (CFS)
184.1
Fecal Limit
200/100ml
DESIGN FLOW (MGD)
3
(If DF >331; Monitor)
DESIGN FLOW (CFS)
4.65
(If DF <331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF)
3.93
UPS BACKGROUND LEVEL
0.22
IWC (%)
2.46
Allowable Conc. (mg/1)
64.4
NPDES Servor/Current Versions/IWC
7/3/02

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