NC0021121_Instream Assessment_19900712

NPDBS DOCUMENT SCANNING COVER SHEET
NPDES Permit:
NC0021121
Mount Airy WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Speculative Limits
Staff Report
Instream Assessment (67B)
Environmental Assessment (EA)
Permit
History
Document Date:
July 12, 1990
This documesat is printed oa reuse paper - ignore any
content oa the reverae aide

DIVISION OF ENVIRONMENTAL MANAGEMENT
July 12, 1990
Memorandum
To: Larry Coble
From: Susan A—Wilsoni
Through: Trevor Clements
Carla Sanderson (�
Subject: Instream Assessment
City of Mt. Airy WWTP
NPDES Permit No. NC0021121
Surry County
SOC No. 89-67
Summary and Recommendations
Technical Support has received the request for an instream assessment for the City of Mount Airy
and has completed the review for the City's Wastewater Treatment Plant.
Mount Airy wishes to increase their flow by one million gallons per day, not to exceed a flow of 5
MGD. The flow increase will consist primarily of industrial discharge from Cross Creek Mills
(formerly Quality Mills). The City also requests that their BODS limit and their current toxicity
limit be modified.
A Level-B analysis was performed to assess the impact of the additional flow and relaxed BODS
limits. The modeling analysis for this assessment indicates that the additional wasteflow under the
proposed interim limits will not cause a violation of EMC 67 (b). Instream water quality standards
should be met at both the pre- and post-SOC conditions. The facility must be able to meet the
limits specified in their permit, for flow exceeding 4 MGD, at the end of the order.
Since the additional wastewater will consist of pretreated industrial process waste, Technical
Support suggests that the facility perform Scute toxicity testing on a monthly basis and show no
acute toxicity at their updated instream waste concentration of 34% (based on an SOC flow of 5
MGD and updated 7Q10 flow of 14.9 cfs). While a toxicity limit is often waived by DEM during
SOC periods, we feel that the City should be held to a minimum requirement of maintaining no
acute toxicity since industrial wastewater additions are being permitted rather than DEM's typical
exclusion of all but domestic strength wastewater. Technical Support also suggests that Mount
Airy perform chronic quarterly monitoring at the IWC (or preferably over a full range of dilutions)
during the life of the Order. This will allow the facility to track their progress toward achieving
final limits prior to expiration of the SOC. It maybe wise to increase the frequency toward the
end of the SOC if the target is not consistently being met.
The Draft Environmental Assessment study prepared and submitted to DEM in March, 1990,
indicated high levels of cadmium (average = 12 ug/l, maximum = 78 ug/1) and copper (average =
356 ug/l, maximum = 810 ug/1). In light of these results, Technical Support recommends weekly
monitoring for cadmium and copper during the Order. In addition to monitoring these metals, we
recommend that the City note the letter sent January 24, 1990, from the Winston-Salem Regional

Office requesting monitoring for banned surfactants. The requirement for monitoring surfactants
should be acknowledged or further detailed in the Order.
Substantial recommendations regarding pretreatment comments are attached with this instream
assessment. Technical Support recommends appropriate milestones be established for the attached
comments in the Order.
Backeround Information
The City of Mount Airy discharges into the Ararat River, which is a class "C" stream in the Yadkin
River Basin. The drainage area at the point of discharge is 75.2 square miles. The 1988 USGS
flows used in the most recent wasteload allocation are as follows: 7Q10 = 14.9 cfs (summer),
average stream flow = 90.0 cfs.
Except for wasteflow, Mount Airy WWTP is currently in compliance with their pre -expansion
permit limitations. However, whole effluent toxicity has been a problem for the facility in the past.
The City is required to conduct the chronic toxicity test at an IWC of 32% for the pre -expansion
flow of 4 MGD. Test results of "pass" have been reported by Mount Airy during each quarterly
reporting month for the past year. Because Mount Airy wishes to add primarily industrial flow
during their SOC to a plant which will be in the process of expansion, the Division stipulated that
certain conditions be met before the City could apply for the Special Order. Specifically in regard
to toxicity, the City had to show that their bench scale effluent could pass the chronic toxicity test at
an instream waste concentration corresponding to the expansion flow of 5 MGD. Also, the bench
scale effluent had to show no acute toxicity at the increased IWC for the interim treatment to be
provided during the SOC period. The City's May report met these conditions.
The May report by Mount Airy's consulting firm, Hazen and Sawyer, showed that the current
BOD5 limit could not be met while the facility was under expansion. Although the facility could
average 50 mg/l BOD5, the City requested 60 mg/l BOD5 during the life of the SOC.
Analysis and Discussion
The Level-B model was run with the region's requested effluent limit of 60 mg/l BOD5 and the
pre-SOC flow of 3.921 MGD. To accomodate the ammonia evident in the last year's effluent
monitoring data, the highest recorded monthly ammonia average, 8.91 mg/l NH3-N, was added to
the model. An effluent DO restriction of 5.0 mg/l was also used in the analyisis. The BOD5 and
NH3-N parapieters were input to the model as CBOD and NBOD using multipliers of 2.0 for
BOD5 and 4.5 for NH3-N (see Table 1). When these effluent characteristics were input to the
model with the pre-SOC flow, the predicted DO sag was 5.10 mg/1 at milepoint 0.26 (see Table
2)
The model was then run with the same inputs for BOD5 and NH3-N using the post-SOC flow of
5.0 MGD, so that the 67 (b) criteria could be evaluated. The Level-B modeling analysis predicted
that the requested flow and limits (5.0 MGD with 60.0 mg/1 BOD5, 5.0 mg/1 DO, and no NH3-N
limit) will meet the EMC 67 (b) criteria for the allowable degradation during an SOC. Specifically,
the DO sag drops to 5.00 mg/l, a decrease of 0.10 mg/l, which is within the criteria.
cc: Steve Tedder
Kent Wiggins
Doug Finan
Ken Eagleson

TABLE 1. INSTREAM ASSESSMENT MODEL INPUT SUMMARY FOR MOUNT AIRY
Wasteflow Assumptions
Design Capacity 4.000 MGD
Pre-SOC 3.921 MGD
Additional SOC Flow Requested 1.000 MGD
Maximum Allowable SOC Flow 5.000 MGD
Model Input Summary
Headwater Conditions (summer) :
7Q10 (cfs)
14.9
Qavg (cfs)
90.0
Design Temperature (°C)
25.0
CBOD (mg/1)
2.0
NBOD (mg/1)
1.0
DO (mg/1)
5.55
Waste Inputs:
Flows
Pre-SOC Flow (year avg) 3.9210 MGD
Post-SOC Flow 5.0000 MGD
CBOD (2.0 * 60 mg/l BOD5) 120.0 mg/l
NBOD (4.5 * 8.91 mg/l N113-N) 40.0 mg/l
TABLE 2. INSTREAM ASSESSMENT MODEL OUTPUT SUMMARY FOR MOUNT AIRY
SOC Evaluation Summer Model Results
Limits:
Pre-SOC SOC
Wasteflow = 3.921 MGD Wasteflow = 5.000 MGD
BOD5 = 60 mg/l = 60 mg/l
NH3-N = no limit = no limit
DO = 5.0 mg/1 = 5.0 mg/1
DO Minumum Net Change
(mid) (mg/1)
------------------
------------------
Pre-SOC 5.10 na
Post-SOC 5.00 0.10

8/89 I
Facility Name ( /� ,t Q Ot kl, A�Yq, I U uJTP Permit # IUC400 �a
ACUTE TOXICITY TESTING REQUIREMENT (MONTHLY)
Fathead Minnow 24hr - No Significant Mortality
The pemtittee shall conduct acute toxicity tests on a monthly basis using protocols defined in the
North Carolina Procedure Document entitled "Pass/Fail Methodology For Determining Acute
Toxicity In A Single Effluent Concentration'. The monitoring shall be performed as a Fathead
Minnow (Pimephales promelas) 24 hour static test, using effluent collected as a 24 hour
composite. The effluent concentration at which there may be at no time significant acute mortality
in any two consecutive toxicity tests is 34% (defined as treatment two in the North Carolina
procedure document). Effluent samples for self -monitoring purposes must be obtained during
representative effluent discharge below all waste treatment. The fast test will be performed within
thirty days from issuance of this permit.
All toxicity testing results required as part of this permit condition will be entered on the Effluent
Discharge Monitoring Form (MR-1) for the month in which it was performed, using the parameter
code TGE6C. Additionally, DEM Form AT-2 (original) is to be sent to the following address:
Attention: Environmental Sciences Branch
North Carolina Division of
Environmental Management
P.O. Box 27687
Raleigh, N.C. 27611
Test data shall be complete and accurate and include all supporting chemical/physical measurements
performed in association with the toxicity tests, as well as all dose/response data. Total residual
chlorine of the effluent toxicity sample must be measured and reported if chlorine is employed for
disinfection of.the waste stream.
Should any test data from either these monitoring requirements or tests performed by the North
Carolina Division of Environmental Management indicate potential impacts to the receiving stream,
this permit may be re -opened and modified to include alternate monitoring requirements or limits.
NOTE: Failure to achieve test conditions as specified in the cited document, such as minimum
control organism survival and appropriate environmental controls, shall constitute an invalid test
and will require immediate retesting(within 30 days of initial monitoring event). Failure to submit
suitable test results will constitute noncompliance with monitoring requirements.
7Q10 /J�. � cfs
Permitted Flow S MGD Recommended by:
IWC% .34
Basin & Sub -Basin ( 0 0
Receiving,Streamyo-m-t FiVgr Pho
County JUYYU. Date 13 0
"Acute Toxicity(Fathead Minnow 24 hr) No Significant Mortality at 34%,
See Part _, Condition .

DIVISION OF ENVIRONMENTAL MANAGEMENT
July 11, 1990
MEMORANDUM
To: Trevor Clements
From: Doug Finan5� A
Subject: Pretreatment Language for the Mt. Airy SOC
Asper -your request, the pretreatment staff has reviewed the
Town of Mt. Airy current status regarding their pretreatment
program and below is the pretreatment language recommended for
possible inclusion in Mt. Airy's SOC:.
:.
1. Submita planY:for.a long-term monitoring program for the
collection of site specific data needed to complete a headworks
analysis -(note: guidance on this was provided in the 1990
pretreatment coordinator's workshop notebook).
2,. Revise the monitoring program (based on DEM comments
received within 90.days of monitoring program submission).
3. upon completion of the upgrade, implement the long-term
monitoring programasrevised based on DEM comments.
4. Develop and submit to DEM for approval an enforcement
management strategy (EMS). '
5. Revise the EMS (based on DEM comments received within 45
days of EMS submission).
.6. Implement the EMS as revised based on DEM comments.
7. Modify the City's SUO as necessary to allow for
implementation of the EMS.
8. Require the City to establish plan for developing an
inventory of industrial chemicals which could reasonably be
expected to be discharged to the wastewater treatment plant.
This plan must include procedures for: obtaining an initial
inventory; determining the treatability of those chemicals
identified in the inventory; requiring the industries to
continually tracking chemical use; and, requiring industries to
provide prior notification to the City when new chemicals are
being added to the inventory.
I have included a few additional comments in red on the draft
SOC: If you have any questions on this matter or require any
further information, please let me know.

st Form for In -stream Assessment for 67B
NAME OF FACILITY �_���/�� /j/� _ 1'/D___ SUBBASZN�n D D%03
-
COUNTY SjaYZ- / REGION�Z .jam ILA DESIGN FLOW
RECEIVING STREAM
BACKGROUND DATA .:
A. Why is SOC needed? (Facility is out of complianc with which
effluent limits?) P �sli/ri%�is SuSic�iii/,QP/0�1S�ii�S�P�S� f0 Fi�f'an
f/o �D/Y6v. �P Prfs��� tt�rAl/iOr7 syslr'� t.",..{{Y/ S� �o��rov� slrvrYP
/:r
'9/- 9� .P�rivc4Yghorr� �iP �oc�/'/y �4
ro.��v/�/n.rtrs< i lusr�r< 3tJ,��
B. History of SOC requests- �'5' !!� ryr(r�'7i+re- 02 D.O.uM.,seFSAT >c�Myp
;I/O%
1. Monthly Average waste flow
prior to any SOC /n O mgd
Time period averaged X Y/ thru�
2. Previously approved SOC's�7����
Date: flow: mgd
Date: flow:- mgd
total of previously approved SOC flow: — mgd
3. Flows lost from plant
(facilities that have gone
off line)
4. Current SOC request
5. Total plant flow post-SOC
(sum of original flow and
SOC flow minus losses)
flow: —' mgd
x
flow: �Dmgd
ii�li^PosYs ��y o��vr
flow:0 mgd
'�Sanr t!5 Gl��
6. Is this an accurate flow balance for plant? Why/why not?
Y5', rrP arP Ile?
r4 �14Wl- 4Yo.J, a l� I'lle e�'

C. Please attach DMR summary for past year for all permitted parame-
ters. If possible, include reports from previous years if
facility has been under SOC for morethana year.
lope
CURRENT SOC_REQUEST :
A. Request is for domestic or industrial waste? If it is a combin-
ation, please specify percentages.
B. What type of industry? Please attach any pertinent data.
;'� S1.7rr/nfr
�O/le�i iiYJi1S LJl/ � Avr'- Or I. 71"YKlMe
C. The region proposes the following SOC limits: J
BOD5 �p0. (� mg/1
NH3 mg/l
DO_ O mg/1
TSSO _mg/l
fecal coliform 0 #/100m1
pH ��7 SU
other parameters_
D. What is the basis for these Jimits? /
ao7' *-7
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I
---------- MODEL RESULTS
Discharger : CITY OF MOUNT AIRY
Receiving Stream : ARARAT RIVER
---------------------------------------------
The End D.O. is 6.67 mg/l.
The End CBOD is 8.57 mg/l.
The End NBOD is 2.58 mg/l.
---------------------------------------------
Segment 1
Reach 1
Reach 2
Reach 3
Reach 4
Reach 5
Reach 6
Reach 7
Reach 8
Segment 2
Reach 1
Segment 3
Reach 1
DO Min
(mg/1) Milepoint Reach #
5.10 0.26 1
5.34 0.00
6.46 0.00
SUMMER fORflEsr Man �`1
BOD5=60, NH3-N=8.91 h/G. ivKFASTVC.
FLOW=3.921 MGD
WLA
CBOD
(mg/1)
120.00
0.00
0.00
0.00
45.00
0.00
0.00
0.00
WLA
NBOD
(mg/1)
40.00
0.00
0.00
0.00
90.00
0.00
0.00
0.00
1
60.00 13.50
1
0.00 0.00
WLA
DO Waste Flow
(mg/1) (mgd)
5.00
3.92100
0.00
0.00000
0.00
0.00000
0.00
0.00000
0.00
0.01800
0.00
0.00000
0.00
0.00000
0.00
0.00000
0.00 1.50000
0.00 0.00000

*** MODEL SUMMARY DATA ***
Discharger
Receiving Stream
Summer 7Q10
Design Temperature
CITY OF MOUNT AIRY
ARARAT RIVER
14.9
25.0
Subbasin : 030703
Stream Class: C
Winter 7Q10 : 31.0
ILENGTHI
SLOPEI
VELOCITY
I DEPTHI Kd I
Kd
I Ka I
Ka I
KN I
--------------------------------------------------------------------------------
I mile I
ft/mil
fps
I ft
Idesignl
@201,�
Idesignl
@203,� Idesignl
Segment
1
I I
1 0.261
I
8.201
0.463
I
1 1.74
I I
1 0.32 1
0.25
I I
1 4.27 1
I
3.831
I
0.44 1
Reach
--------------------------------------------------------------------------------
1
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 0.721
I
8.201
0.527
I
1 1.95
I I
1 0.32 1
0.26
I I
1 3.85 1
I
3.451
I
0.44 1
Reach
--------------------------------------------------------------------------------
2
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 1.201
I
8.201
0.675
I
1 2.30
I I
1 0.33 1
0.26
I I
1 3.38 1
I
3.031
I
0.44 1
Reach
--------------------------------------------------------------------------------
3
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 2.201
I
8.201
0.679
I
1 2.33
I I
1 0.33 1
0.26
I I
1 3.33 1
I
2.981
I
0.44 1
Reach
--------------------------------------------------------------------------------
4
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 1.651
I
8.201
0.688
I
1 2.34
I I
1 0.33 1
0.26
I I
1 3.33 1
I
2.991
I
0.44 1
Reach
--------------------------------------------------------------------------------
5
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 2.101
I
10.501
0.744
I
1 2.28
I I
1 0.35 1
0.28
I I
1 3.61 1
I
3.241
I
0.44 1
Reach
--------------------------------------------------------------------------------
6
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 2.001
I
10.501
0.759
I
1 2.31
I I
1 0.35 1
0.28
I I
1 3.57 1
I
3.201
I
0.44 1
Reach
--------------------------------------------------------------------------------
7
1 1
1
1
1 1
1 1
1
1
Segment
1
I I
1 2.501
I
6.501
0.686
I
1 2.51
I I
1 0.31 1
0.25
I . I
1 4.37 1
I
3.921
I
0.44 1
Reach
--------------------------------------------------------------------------------
8
1 1
1
1
1 1
1 1
1
1
Segment
2
I I
1 3.601
I
11.831
0.343
I
1 1.30
I I
1 0.34 1
0.27
I I
1 8.15 1
I
7.311
I
0.44 1
Reach
--------------------------------------------------------------------------------
1
1 1
1
1
1 1
1 1
1
1
Segment
3
I I
1 2.301
I
6.501
0.740
I
1 2.65
I I
1 0.31 1
0.25
I I
1 4.72 1
I
4.231
I
0.44 1
Reach
--------------------------------------------------------------------------------
1
1 1
1
1
1 1
1 1
1
1
I Flow I CBOD I NBOD I D.O. I
I cfs I mg/l I mg/l I mg/l I
Segment 1 Reach 1

Waste
1 6.078
1120.000
1 40.000 1
5.000
Headwatersl 14.900
1 2.000
1 1.000 1
5.550
Tributary
1 0.000
1 2.000
1 1.000 1
7.440
* Runoff
1 0.080
I 2.000
1 1.000 1
7.440
Segment 1
Reach 2
Waste
I 0.000
I 0.000
1 0.000 1
0.000
Tributary
1 8.900
I 2.000
I 1.000 1
7.440
* Runoff
1. 0.080
I 2.000
I 1.000 I
7.440
Segment 1
Reach 3
Waste
I 0.000
1 0.000
1 0.000 1
0.000
Tributary
1 23.600
1 2.000
1 1.000 1
7.440
* Runoff
1 0.380
1 2.000
1 1.000 1
7.440
Segment 1
Reach 4
Waste
I 0.000
I 0.000
1 0.000 1
0.000
Tributary
1 0.800
1 2.000
1 1.000 1
7.440
* Runoff
I 0.580
I 2.000
I 1.000 I
7.440
Segment 1
Reach 5
Waste
1 0.028
145.000
190.000 1
0.000
Tributary
1 0.000
I 2.000
1 1.000 1
7.440
* Runoff
1 0.580
I 2.000
1 1.000 1
7.440
Segment 1
Reach 6
Waste
1 0.000
1 0.000
1 0.000 1
0.000
Tributary
1 0.380
1 2.000
1 1.000 1
7.440
* Runoff
1 0.380
I 2.000
I 1.000 1
7.440
Segment 1
Reach 7
Waste
I 0.000
1 0.000
I 0.000 I
0.000
Tributary
I 0.770
I 2.000
1 1.000 1
7.440
* Runoff
I 1.700
I 2.000
1 1.000 1
7.440
Segment 1
Reach 8
Waste
1 0.000
I 0.000
I 0.000 1
0.000
Tributary
1 0.000
1 2.000
1 1.000 1
0.000
* Runoff
1 1.700
1 2.000
1 1.000 1
7.440
Segment 2 Reach 1
Waste 1
2.325
160.000
113.500 1
0.000
Headwatersl
5.930
I 2.000
I 1.000 1
7.440
Tributary I
0.000
I 2.000
I 1.000 1
0.000
* Runoff I
0.260
1 2.000
1 1.000 1
7.440
Segment 3 Reach 1
Waste 1
0.000 1
0.000 1
0.000 1
0.000
Headwatersl
0.000 1
2.000 1
1.000 1
0.000
Tributary 1
0.000 1
2.000 1
1.000 1
0.000
* Runoff 1
1.700 1
2.000 1
1.000 1
7.440

SUMMER
BOD5=60,
NH3-N=8.91
FLOW=3.921 MGD
Seg #
I Reach #
I Seg Mi I
D.O. I
CBOD I
NBOD I
Flow I
1
1
0.00
5.39
36.19
12.30
20.98
1
1
0.02
5.37
36.15
12.28
20.98
1
1
0.04
5.34
36.12
12.27
20.98
1
1
0.06
5.32
36.09
12.25
20.98
1
1
0.08
5.29
36.05
12.24
20.98
1
1
0.10
5.27
36.02
12.22
20.99
1
1
0.12
5.25
35.99
12.21
20.99
1
1
0.14
5.23
35.96
12.19
20.99
1
1
0.16
5.20
35.92
12.18
20.99
1
1
0.18
5.18
35.89
12.16
20.99
1
1
0.20
5.16
35.86
12.15
20.99
1
1
0.22
5.14
35.82
12.13
21.00 '
1
1
0.24
5.12
35.79
12.12
21.00
1
1
0.26
5.10
35.76
12.10
21.00
1
2
0.26
5.79
25.71
8.80
29.90
1
2
0.30
5.76
25.67
8.78
29.90
1
2
0.34
5.73
25.63
8.76
29.90
1
2
0.38
5.70
25.59
8.74
29.91
1
2
0.42
5.67
25.55
8.72
29.91
1
2
0.46
5.65
25.51
8.70
29.91
1
2
0.50
5.62
25.47
8.69
29.92
1
2
0.54
5.59
25.43
8.67
29.92
1
2
0.58
5.56
25.38
8.65
29.92
1
2
0.62
5.54
25.34
8.63
29.93
1
2
0.66
5.51
25.30
8.61
29.93
1
2
0.70
5.49
25.26
8.59
29.93
1
2
0.74
5.46
25.22
8.58
29.94
1
2
0.78
5.44
25.18
8.56
29.94
1
2
0.82
5.41
25.14
8.54
29.94
1
2
0.86
5.39
25.10
8.52
29.95
1
2
0.90
5.37
25.06
8.50
29.95
1
2
0.94
5.35
25.02
8.48
29.95
1
2
0.98
5.33
24.99
8.47
29.96
1
3
0.98
6.26
14.86
5.18
53.56
1
3
1.18
6.19
14.75
5.13
53.63
1
3
1.38
6.13
14.65
5.08
53.71
1
3
1.58
6..07
14.54
5.04
53.78
1
3
1.78
6.02
14.44
4.99
53.86
1
3
1.98
5.97
14.34
4.95
53.94
1
3
2.18
5.93
14.23
4.90
54.01
1
4
2.18
5.95
14.06
4.84
54.81
1
4
2.38
5.91
13.95
4.80
54.93
1
4
2.58
5.88
13.84
4.75
55.04
1
4
2.78
5.84
13.74
4.71
55.16
1
4
2.98
5.81
13.63
4.66
55.28
1
4
3.18
5.78
13.53
4.62
55.39
1
4
3.38
5.76
13.42
4.57
55.51
1
4
3.58
5.73
13.32
4.53
55.62
1
4
3.78
5.71
13.22
4.49
55.74
1
4
3.98
5.69
13.12
4.44
55.86
1
4
4.18
5.68
13.02
4.40
55.97
1
4
4.38
5.66
12.92
4.36
56.09
1
5
4.38
5.66
12.94
4.40
56.12
1
5
4.43
5.66
12.91
4.39
56.14
1
5
4.48
5.65
12.89
4.38
56.17
1
5
4.53
5.65
12.86
4.37
56.20 .

5
5
5
5
5
5
5
5
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
6
7
7
7
7
7
7
4.58,
5.65
12.84
4.36
56.23
4.63
5.65
12.82
4.35
56.26
4.68
5.64
12.79
4.34
56.29
4.73
5.64
12.77
4.33
56.32
4.78
5.64
12.74
4.32
56.35
4.83
5.63
12.72
4.31
56.38
4.88
5.63
12.70
4.30
56.41
4.93
5.63
12.67
4.29
56.43
4.98
5.63
12.65
4.28
56.46
5.03
5.63
12.62
4.27
56.49
5.08
5.62
12.60
4.26
56.52
5.13
5.62
12.58
4.25
56.55
5.18
5.62
12.55
4.24
56.58
5.23
5.62
12.53
4.23
56.61
5.28
5.62
12.51
4.22
56.64
5.33
5.61
12.48
4.21
56.67
5.38
5.61
12.46
4.20
56.70
5.43
5.61
12.44
4.19
56.72
5.48
5.61
12.41
4.18
56.75
5.53
5.61
12.39
4.17
56.78
5.58
5.61
12.37
4.16
56.81
5.63
5.61
12.34
4.15
56.84
5.68
5.60
12.32
4.14
56.87
5.73
5.60
12.30
4.13
56.90
5.78
5.60
12.27
4.12
56.93
5.83
5.60
12.25
4.11
56.96
5.88
5.60
12.23
4.10
56.99
5.93
5.60
12.20
4.09
57.01
5.98
5.60
12.18
4.08
57.04
6.03
5.60
12.16
4.07
57.07
6.03
5.61
12.09
4.05
57.45
6.13
5.61
12.05
4.04
57.49
6.23
5.61
12.01
4.02
57.53
6.33
5.62
11.97
4.00
57.57
6.43
5.62
11.93
3.99
57.60
6.53
5.62
11.89
3.97
57.64
6.63
5.62
11.85
3.95
57.68
6.73
5.62
11.81
3.94
57.72
6.83
5.63
11.77
3.92
57.76
6.93
5.63
11.73
3.91
57.79
7.03
5.63
11.69
3.89
57.83
7.13
5.63
11.65
3.87
57.87
7.23
5.64
11.61
3.86
57.91
7.33
5.64
11.57
3.84
57.95
7.43
5.64
11.53
3.83
57.98
7.53
5.64
11.49
3.81
58.02
7.63
5.65
11.45
3.80
58.06
7.73
5.65
11.41
3.78
58.10
7.83
5.65
11.37
3.76
58.14
7.93
5.66
11.33
3.75
58.17
8.03
5.66
11.29
3.73
58.21
8.13
5.66
11.26
3.72
58.25
8.13
5.69
11.14
3.68
59.02
8.23
5.69
11.08
3.66
59.19
8.33
5.70
11.02
3.64
59.36
8.43
5.71
10.96
3.62
59.53
8.53
5.71
10.91
3.60
59.70
8.63
5.72
10.85
3.58
59.87
8.73
5.72
10.80
3.56
60.04
8.83
5.73
10.74
3.54
60.21

1
7
8.93
5.74
10.69
3.52
60.38
1
7
9.03
5.74
10.63
3.50
60.55
1
7
9.13
5.75
10.58
3.48
60.72
1
7
9.23
5.76
10.53
3.46
60.89
1
7
9.33
5.76
10.47
3.44
61.06
1
7
9.43
5.77
10.42
3.43
61.23
1
7
9.53
5.78
10.37
3.41
61.40
1
7
9.63
5.78
10.31
3.39
61.57
1
7
9.73
5.79
10.26
3.37
61.74
1
7
9.83
5.80
10.21
3.35
61.91
1
7
9.93
5.80
10.16
3.33
62.08
1
7
10.03
5.81
10.11
3.31
62.25
1
7
10.13
5.82
10.06
3.30
62.42
1
8
10.13
5.82
10.06
3.30
62.42
1
8
10.38
5.89
9.94
3.25
62.85
1
8
10.63
5.95
9.81
3.20
63.27
1
8
10.88
6.01
9.69
3.16
63.70
1
8
11.13
6.07
9.58
3.11
64.12
1
8
11.38
6.12
9.46
3.07
64.55
1
8
11.63
6.17
9.35
3.02
64.97
1
8
11.88
6.21
9.23
2.98
65.40
1
8
12.13
6.25
9.12
2.94
65.82
1
8
12.38
6.29
9.01
2.90
66.25
1
8
12.63
6.32
8.91
2.86
66.67
2
1
0.00
5.34
18.34
4.52
8.25
2
1
0.30
6.04
17.86
4.38
8.33
2
1
0.60
6.49
17.40
4.25
8.41
2
1
0.90
6.80
16.95
4.12
8.49
2
1
1.20
7.00
16.52
4.00
8.57
2
1
1.50
7.13
16.09
3.88
8.64
2
1
1.80
7.23
15.68
3.76
8.72
2
1
2.10
7.30
15.29
3.65
8.80
2
1
2.40
7.35
14.90
3.54
8.88
2
1
2.70
7.39
14.52
3.44
8.96
2
1
3.00
7.43
14.16
3.34
9.03
2
1
3.30
7.46
13.81
3.24
9.11
2
1
3.60
7.48
13.46
3.15
9.19
3
1
0.00
6.46
9.46
2.89
75.86
3
1
0.23
6.49
9.36
2.86
76.25
3
1
0.46
6.52
9.27
2.83
76.64
3
1
0.69
6.54
9.18
2.79
77.03
3
1
0.92
6.56
9.09
2.76
77.43
3
1
1.15
6.58
9.00
2.73
77.82
3
1
1.38
6.60
8.91
2.70
78.21
3
1
1.61
6.62
8.82
2.67
78.60
3
1
1.84
6.64
8.74
2.64
78.99
3
1
2.07
6.65
8.65
2.61
79.38
3
1
2.30
6.67
8.57
2.58
79.77
I Seg #
I Reach #
I Seg Mi I
D.O. I
CBOD I
NBOD I
Flow

MODEL RESULTS
Discharger : CITY OF MOUNT AIRY
Receiving Stream : ARARAT RIVER
---------------------------------------------
The End D.O. is 6.53 mg/l.
The End CBOD is 10.06 mg/l.
The End NBOD is 3.02 mg/l.
---------------------------------------------
Segment 1
Reach 1
Reach 2
Reach 3
Reach 4
Reach 5
Reach 6
Reach 7
Reach 8
Segment 2
Reach 1
Segment 3
Reach 1
DO Min
(mg/1) Milepoint Reach #
----------------------
5.00 0.26 1
5.34 0.00
6.28 0.00
SUMMER
BOD5=60, NH3-N 8. 91J "'41Esr MONI L4
FLOW=5 . 0 MGD AW' FOR �/Kt 'f�•
WLA
CBOD
(mg/1)
120.00
0.00
0.00
0.00
45.00
0.00
0.00
0.00
WLA
NBOD
(mg/1)
40.00
0.00
0.00
0.00
90.00
0.00
0.00
0.00
1
60.00 13.50
1
0.00 0.00
WLA
DO Waste Flow
(mg/1) (mgd)
5.00
5.00000
0.00
0.00000
0.00
0.00000
0.00
0.00000
0.00
0.01800
0.00
0.00000
0.00
0.00000
0.00
0.00000
0.00 1.50000
0.00 0.00000

*** MODEL SUMMARY DATA ***
Discharger : CITY OF MOUNT AIRY
Receiving Stream : ARARAT RIVER
Summer 7Q10 : 14.9
Design Temperature: 25.0
Subbasin : 030703
Stream Class: C
Winter 7Q10 : 31.0
ILENGTHI
SLOPEI
VELOCITY
I DEPTHI Kd I
Kd
I Ka I
Ka I
KN I
--------------------------------------------------------------------------------
I mile I
ft/mil
fps
I ft
Idesignl
@2014
Idesignl
@201h Idesignl
Segment
1
I I
1 0.26I
I
8.20I
0.491
I
1 1.75
I I
1 0.32 1
0.26
I I
1 4.33 1
I
3.891
I
0.44 1
Reach
--------------------------------------------------------------------------------
1
1 1
I
I
I I
I I
I
1
Segment
1
I I
1 0.72I
I
8.201
0.549
I
1 1.96
I I
10.32 1
0.26
I I
1 3.89 I
I
3.481
I
0.44 1
Reach
--------------------------------------------------------------------------------
2
I 1
I
1
1 I
I I
1
1
Segment
1
I I
I 1.201
I
8.201
0.691
I
1 2.31
I I
10.33 10.26
I I
13.40 I
I
3.051
I
0.44 1
Reach
--------------------------------------------------------------------------------
3
I I
I
1
I I
I I
I
1
Segment
1
I I
1 2.20I
I
8.201
0.695
I
1 2.34
I I
1 0.33 1
0.26
I I
1 3.35 1
I
3.001
I
0.44 1
Reach
--------------------------------------------------------------------------------
4
I I
I
I
I I
I I
1
1
Segment
1
I I
1 1.651
I
8.201
0.704
I
1 2.35
I I
10.33 10.26
I I
13.35 I
I
3.00I
I
0.44 1
Reach
--------------------------------------------------------------------------------
5
I I
I
1
I 1
I I
I
I
Segment
1
I I
I 2.101
I
10.501
0.761
I
1 2.28
I I
10.35 1
0.28
I I
1 3.63 I
I
3.261
I
0.44 1
Reach
--------------------------------------------------------------------------------
6
I I
I
I
I I
I I
I
1
Segment
1
I I
1 2.001
I
10.501
0.775
I
12.32
I I
1 0.35 10.28
I I
1 3.59 I
I
3.221
I
0.44 1
Reach
--------------------------------------------------------------------------------
7
I 1
1
1
1 1
1 1
1
1
Segment
1
I I
I 2.501
I
6.501
0.699
I
1 2.51
I I
1 0.31 10.25
I I
1 4.46 1
I
4.001
I
0.44 1
Reach
--------------------------------------------------------------------------------
8
I I
I
I
I I
I I
I
1
Segment
2
I I
1 3.601
I
11.831
0.343
I
1 1.30
I I
10.34 1
0.27
I I
1 8.15 1
I
7.311
I
0.44 1
Reach
--------------------------------------------------------------------------------
1
1 I
1
1
1 1
1 1
1
1
Segment
3
I I
1 2.301
I
6.501
0.752
I
1 2.66
I I
10.31 1
0.25
I I
14.79 1
I
4.301
I
0.44 1
Reach
--------------------------------------------------------------------------------
1
1 I
I
I
1 1
I I
I
1
I Flow I CBOD I NBOD I D.O. I
I 'cfs I mg/l I mg/l I mg/1 I
Segment 1 Reach 1

Waste
1 7.750
1120.000 1
40.000 1
5.000
Headwatersl 14.900
1 2.000
1 1.000 1
5.550
Tributary
I 0.000
I 2.000 I
1.000 I
7.440
* Runoff
I 0.080
I 2.000
I 1.000 I
7.440
Segment 1
Reach 2
Waste
1 0.000
1 0.000
1 0.000 1
0.000
Tributary
I 8.900
I 2.000
1 1.000 I
7.440
* Runoff
1 0.080
I 2.000 I
1.000 I
7.440
Segment 1
Reach 3
Waste
I 0.000
I 0.000 I
0.000 I
0.000
Tributary
1 23.600
I 2.000 I
1.000 I
7.440
* Runoff
1 0.380
I 2.000 I
1.000 1
7.440
Segment 1
Reach 4
Waste
I 0.000
I 0.000 1
0.000 1
0.000
Tributary
I 0.800
I 2.000 1
1.000 1
7.440
* Runoff
I 0.580
1 2.000 1
1.000 1
7.440
Segment 1
Reach 5
Waste
I 0.028
145.000 1
90.000 I
0.000
Tributary
I 0.000
1 2.000 1
1.000 I
7.440
* Runoff
I 0.580
1 2.000 1
1.000 1
7.440
Segment 1
Reach 6
Waste
I 0.000
I 0.000 I
0.000 I
0.000
Tributary
I 0.380
I 2.000 I
1.000 1
7.440
* Runoff
I 0.380
I 2.000 I
1.000 1
7.440
Segment 1
Reach 7
Waste
I 0.000
I 0.000 1
0.000 1
0.000
Tributary
I 0.770
I 2.000 I
1.000 1
7.440
* Runoff
I 1.700
I 2.000 I
1.000 I
7.440
Segment 1
Reach 8
Waste
I 0.000
I 0.000
I 0.000 I
0.000
Tributary
1 0.000
I 2.000
I 1.000 1
0.000
* Runoff
I 1.700
I 2.000
I 1.000 I
7.440
Segment 2 Reach 1
Waste 1
2.325 1
60.000
1 13.500 1
0.000
Headwatersl
5.930
1 2.000
1 1.000 1
7.440
Tributary I
0.000
1 2.000
1 1.000 1
0.000
* Runoff I
0.260
1 2.000
1 1.000 1
7.440
Segment 3 Reach 1
Waste 1
0.000 1
0.000 1
0.000 1
0.000
Headwatersl
0.000 1
2.000 1
1.000 1
0.000
Tributary l
0.000 I
2.000 I
1.000 1
0.000
* Runoff 1
1.700 I
2.000 I
1.000 1
7.440

SUMMER
BOD5=60,
NH3-N=8.91
FLOW=5.0
MGD
I Seg #
I Reach #
I Seg Mi I
D.O. I
CBOD I
NBOD I
Flow I
1
1
0.00
5.36
42.38
14.34
22.65
1
1
0.02
5.33
42.34
14.33
22.65
1
1
0.04
5.30
42.30
14.31
22.65
1
1
0.06
5.27
42.26
14.29
22.65
1
1
0.08
5.25
42.23
14.28
22.66
1
1
0.10
5.22
42.19
14.26
22.66
1
1
0.12
5.19
42.15
14.24
22.66
1
1
0.14
5.16
42.12
14.23
22.66
1
1
0.16
5.13
42.08
14.21
22.66
1
1
0.18
5.11
42.04
14.19
22.66
1
1
0.20
5.08
42.01
14.18
22.67
1
1
0.22
5.05
41.97
14.16
22.67
1
1
0.24
5.03
41.93
14.15
22.67
1
1
0.26
5.00
41.90
14.13
22.67
1
2
0.26
5.69
30.65
10.43
31.57
1
2
0.30
5.65
30.60
10.41
31.57
1
2
0.34
5.61
30.56
10.39
31.58
1
2
0.38
5.58
30.51
10.36
31.58
1
2
0.42
5.54
30.46
10.34
31.58
1
2
0.46
5.51
30.42
10.32
31.59
1
2
0.50
5.47
30.37
10.30
31.59
1
2
0..54
5.44
30.32
10.28
31.59
1
2
0.58
5.41
30.28
10.26
31.60
1
2
0.62
5.37
30.23
10.24
31.60
1
2
0.66
5.34
30.18
10.22
31.60
1
2
0.70
5.31
30.14
10.19
31.61
1
2
0.74
5.28
30.09
10.17
31.61
1
2
0.78
5.25
30.04
10.15
31.61
1
2
0.82
5.22
30.00
10.13
31.62
1
2
0.86
5.19
29.95
10.11
31.62
1
2
0.90
5.17
29.91
10.09
31.62
1
2
0.94
5.14
29.86
10.07
31.63
1
2
0.98
5.11
29.81
10.05
31.63
1
3
0.98
6.11
17.93
6.18
55.23
1
3
1.18
6.03
17.80
6.13
55.30
1
3
1.38
5.95
17.68
6.07
55.38
1
3
1.58
5.89
17.56
6.02
55.46
1
3
1.78
5.82
17.43
5.97
55.53
1
3
1.98
5.76
17.31
5.91
55.61
1
3
2.18
5.71
17.19
5.86
55.68
1
4
2.18
5.73
16.97
5.79
56.48
1
4
2.38
5.68
16.85
5.74
56.60
1
4
2.58
5.64
16.72
5.68
56.72
1
4
2.78
5.60
16.59
5.63
56.83
1
4
2.98
5.56
16.47
5.58
56.95
1
4
3.18
5.53
16.34
5.52
57.06
1
4
3.38
5.49
16.22
5.47
57.18
1
4
3.58
5.47
16.10
5.42
57.30
1
4
3.78
5.44
15.98
5.37
57.41
1
4
3.98
5.42
15.86
5.32
57.53
1
4
4.18
5.40
15.74
5.27
57.64
1
4
4.38
5.38
15.62
5.22
57.76
1
5
4.38
5.37
15.64
5.26
57.79
1
5
4.43
5.37
15.61
5.25
57.82
1
5
4.48
5.37
15.58
5.24
57.85
1
5
4.53
5.36
15.55
5.23
57.88

1
1
1
1
1
1
4.58
5.36
15.52
5.21
57.90
4.63
5.35
15.49
5.20
57.93
4.68
5.35
15.46
5.19
57.96
4.73
5.35
15.43
5.18
57.99
4.78
5.34
15.41
5.16
58.02
4.83
5.34
15.38
5.15
58.05
4.88
5.34
15.35
5.14
58.08
4.93
5.33
15.32
5.13
58.11
4.98
5.33
15.29
5.12
58.14
5.03
5.33
15.26
5.11
58.17
5.08
5.33
15.23
5.09
58.19
5.13
5.32
15.21
5.08
58.22
5.18
5.32
15.18
5.07
58.25
5.23
5.32
15.15
5.06
58.28
5.28
5.32
15.12
5.05
58.31
5.33
5.31
15.09
5.04
58.34
5.38
5.31
15.07
5.02
58.37
5.43
5.31
15.04
5.01
58.40
5.48
5.31
15.01
5.00
58.43
5.53
5.31
14.98
4.99
58.46
5.58
5.30
14.95
4.98
58.48
5.63
5.30
14.93
4.97
58.51
5.68
5.30
14.90
4.95
58.54
5.73
5.30
14.87
4.94
58.57
5.78
5.30
14.84
4.93
58.60
5.83
5.30
14.82
4.92
58.63
5.88
5.29
14.79
4.91
58.66
5.93
5.29
14.76
4.90
58.69
5.98
5.29
14.73
4.89
58.72
6.03
5.29
14.71
4.87
58.75
6.03
5.31
14.63
4.85
59.13
6.13
5.31
14.58
4.83
59.16
6.23
5.31
14.53
4.81
59.20
6.33
5.31
14.48
4.79
59.24
6.43
5.31
14.43
4.77
59.28
6.53
5.31
14.38
4.75
59.32
6.63
5.31
14.33
4.73
59.35
6.73
5.32
14.28
4.71
59.39
6.83
5.32
14.24
4.70
59.43
6.93
5.32
14.19
4.68
59.47
7.03
5.32
14.14
4.66
59.51
7.13
5.32
14.09
4.64
59.54
7.23
5.33
14.05
4.62
59.58
7.33
5.33
14.00
4.60
59.62
7.43
5.33
13.95
4.58
59.66
7.53
5.33
13.91
4.56
59.70
7.63
5.34
13.86
4.55
59.73
7.73
5.34
13.81
4.53
59.77
7.83
5.34
13.77
4.51
59.81
7.93
5.35
13.72
4.49
59.85
8.03
5.35
13.67
4.47
59.89
8.13
5.35
13.63
4.46
59.92
8.13
5.38
13.48
4.41
60.69
8.23
5.39
13.41
4.39
60.86
8.33
5.40
13.34
4.36
61.03
8.43
5.40
13.27
4.34
61.20
8.53
5.41
13.21
4.31
61.37
8.63
5.42
13.14
4.29
61.54
8.73
5.42
13.07
4.27
61.71
8.83
5.43
13.01
4.24
61.88

1
1
1
1
2
2
2
2
2
2
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
3
3
I Seg #
7
8..93
5.44
12.94
4.22
62.05
7
9.03
5.45
12.87
4.19
62.22
7
9.13
5.45
12.81
4.17
62.39
7
9.23
5.46
12.74
4.15
62.56
7
9.33
5.47
12.68
4.13
62.73
7
9.43
5.48
12.62
4.10
62.90
7
9.53
5.48
12.55
4.08
63.07
7
9.63
5.49
12.49
4.06
63.24
7
9.73
5.50
12.43
4.04
63.41
7
9.83
5.50
12.36
4.01
63.58
7
9.93
5.51
12.30
3.99
63.75
7
10.03
5.52
12.24
3.97
63.92
7
10.13
5.53
12.18
3.95
64.09
8
10.13
5.53
12.18
3.95
64.09
8
10.38
5.61
12.03
3.89
64.52
8
10.63
5.69
11.88
3.83
64.94
8
10.88
5.76
11.74
3.78
65.37
8
11.13
5.82
11.60
3.73
65.79
8
11.38
5.88
11.46
3.67
66.22
8
11.63
5.94
11.32
3.62
66.64
8
11.88
5.99
11.18
3.57
67.07
8
12.13
6.04
11.05
3.52
67.49
8
12.38
6.08
10.92
3.47
67.92
8
12.63
6.12
10.79
3.42
68.34
1
0.00
5.34
18.34
4.52
8.25
1
0.30
6.04
17.86
4.38
8.33
1
0.60
6.49
17.40
4.25
8.41
1
0.90
6.80
16.95
4.12
8.49
1
1.20
7.00
16.52
4.00
8.57
1
1.50
7.13
16.09
3.88
8.64
1
1.80
7.23
15.68
3.76
8.72
1
2.10
7.30
15.29
3.65
8.80
1
2.40
7.35
14.90
3.54
8.88
1
2.70
7.39
14.52
3.44
8.96
1
3.00
7.43
14.16
3.34
9.03
1
3.30
7.46
13.81
3.24
9.11
1
3.60
7.48
13.46
3.15
9.19
1
0.00
6.28
11.10
3.39
77.53
1
0.23
6.31
10.99
3.35
77.93
1
0.46
6.34
10.88
3.31
78.32
1
0:69
6.37
10.78
3.27
78.71
1
0.92
6.40
10.67
3.23
79.10
1
1.15
6.42
10.56
3.20
79.49
1
1.38
6.45
10.46
3.16
79.88
1
1.61
6.47
10.36
3.12
80.27
1
1.84
6.49
10.26
3.09
80.66
1
2.07
6.51
10.16
3.05
81.05
1
2.30
6.53
10.06
3.02
81.44
I Reach #
I Seg Mi I
D.O. I
CBOD I
NBOD I
Flow

INSTREAM SELF -MONITORING DATA
MONTHLY AVERAGES
Discharger: /bt;, ji2y Permit No.: NC00
Receiving Stream: A"AizA-r P-v,2. Sub -basin:
Upstream Location: u5 uw4 52 Fx_xe Downstream Location S2 1,77,a DrAo Fvy
DATE
DEC-90
NOV- 90
OCT-90
SEP-90
AUG-90
JUL-90
JUN-90
MAY-90
APR-90
MAR- 90
FEB-90
JAN-90
DEC-89
NOV- 89
OCT-89
SEP-89
AUG-89
JUL-89
JUN-89
MAY-89
APR-89
MAR-89
FEB-89
JAN-89
DEC-88
NOV- 88
OCT-88
SEP-88
AUG-88
JUL-88
JUN-88
MAY-88
APR-88
MAR- 88
FEB-88
JAN-88
DEC-87
NOV-87
OCT-87
SEP-87
AUG-87
JUL-87
JUN-87
MAY-87
APR-87
MAR-87
FEB-87
JAN-87
Upstream Downstream
TEMP D.O. BOD5 COND TEMP D.O. zon
FFIA I- p6CAL
Zo•Ig
�Z/ys� 242
/9.`I
267&0
300
l6. 1
0, (6,5) Zd7
JG• Z
Z¢7(G.9)
Zs 6
9 22
0, (9.Q-) ZZfi
q.d%a).344
b.72(1)
it, 5 94R
17,17
n, ss
/ 3 ,
i3.3
9,W7
13.4¢
8.%1'7,4)
Z96
i7. Z
00-7.0) 7-35-
17.7
R-'3
� 07(:StJ 316.4
/q.7
�•iS/S>?
/2�
2z.7_
a
r>.*(-3)
90�
7. Z
•0) 213
/10
7. 2 (6.0)
2� ��
COND

�-
No Mq, —nl a2D/Z
-p", CorL, .L S 3 — -7r 5 Z

......u..r .•. iuu Il, IYYV
REQUIREMENT
...
...i..
rc'
MDESN:
PERMITCHRONIC LIMR:94%FEB
MAR
A 'R
MAY
..
AN
NPDFSA: N�6'/28
OD040M
&9in:4A/89 Q P/P a
P1Moo�
'86
.
y
Coonry: IREDE1L
Ragim:MRO
:
MmW: FEB MAY AUG NOV
•g8
(PASS)
-
(FAIL)
-
PP:310
SOCpOC Rcq:
QrgR,)
_
-
<-)
FAIL
-
_
p'AR)"
7Q1P.03
IWC(A):94.15
F
FAIL
-
PASS
PASS
NR
-
PASS
NR
PASS
M00.pANR$RG
PERMAi CHRONICLIMR;99%
90
PASS
-
_
_
PASS
-
fiRDESX: NC006W4]
&gum 10'1/88 Q
.1
'61
Cowry: HARNE3T
Regim: FRO
M. o: N
MmW: lAN APR lUL OCT
'89
PP:0.026
SOCnOC Rom:
7Q10: 0.00
IWC{%):I0000
NR
NR
FAIL
U7H
PASS
90 NR
PASS
-
NR
-
M
FAIL
FAIL
MO W
PERMIT CHRONIC LIMIT9AA
ESN: NCN
NI'DESA: NC0026573
73
Begm 12/1/87 Preq'rny, Q P/P
16
Cuvnry: BURR
Regim; MRO
JAN APR JUL OCT
illFAIL
-
-
-
_
_
PP: amMmW:
SOCDOC Req:
'H9 PASS
-
(-)
-;
PASS
(-)
PASS
-
-
PASS
-
_
(hR)
7Q10:126.00
IWC(%):8.96
-
-
PASS
-
PASS
-
_
90 PASS
-
-
PASS
-
PASS
-
_
MORR W WIP
ERROR FOUND W/SAMPLE COILEC170N
'86
h-PDPSN: A: N0]CNCDO d0938
Bcgm OQW/D0 P1O n D
.
Cncvry: WAKE
Region: PRO
Manm011
8J
'88
PP:0.15
:
SOp10C Rio,:
'89
7Q10: 0.00
RVC(%)100.00
,90
MORRISVd1E WWIP-CRABTREE
LLTTERCHRONICTARGEP:38%
'86
NPDESA: U41
Reg6c3/l/88 R-R"Y M P/F
87
Cowry: WAKE
AKE W
Rceim:RRO
MmW:
PP:0.20
SOCJIOC Req:
'89
PASS
NR "
NR
HE
NR
NR
7Q10: o.30
IWC(%):78.27
NR
NR
NR
NR
HE
NR
NR
NR
NR
NR
NR
90 NR
PASS
NR
NR
NR
NR
NR
W. AIRY WWTP
PERMITCHRLIMMJ2%,42%@d MGD&COMPLIANT
NPDPSA: Nm021121
&gW 5/1E189 Q P/P d
V'8615.S
•87 NR
M
26.2
13.19
39.i-
21.47
NONE
P30
NONE
NO NE/)'
P151F
Cowry: SORRY
Regim: WSRO
MmW: JUL OCPIAN APR
'88
J],P
NONHP
P40
89.99
(PASS)
-
-
(PASS)
NONE/P
PP;
SOC/IOC Rcq:
-
'89
(PAIL)
PASS
-
'PASS
-
(PASS)
7Q10: 13.0
13.
RVC(%):3L2
FAIL
-
-
PAR.
FAIL
PAd
FAIL
PASS
PASS
-
FAR,
90 PASS
_
_
P,P
PASS
b�
_
q'R.HOILYWWIE
PERMIT CHRONIC LIMlr:6.1%
WDRSA: NC0021156
BegW a/I/g8 F" q^,r Q 9/F
'86
.1
Cowry: GASTON
Regim: MRO
MmW: MAY AUG NOV FEB
188
PF: 4.00
SOCROC Req;
-
'89 -
PASS
(NR)
-
NONE
(-)
NONE
PASS
-
PASS
7QI0: 93.00
IWC(%):6.10
-
-
PASS
-
-
PASS
90 -
PASS
-
-
PASS
-
-
PASS
-
dDESP:NPIGKLE
PERMITCHItONIC LIMIT:99A
'86-
1PDESA: N(A0010]4
Begin I/I/88 Regm¢y- Q PIP
'87 19
_
_
-
-
-
-
-
-
-
Cavmy: WAYNE
Regim: WARD
MmW: FEB MAYAUO NOV
.88 (16)
10
27
NR
23
RP
18
14
15
13
NR
<5.0
10.5
PF:0.40
SOC130C Re,
32
-
(Igo
-
-
(-)
-
NR
NR
7QI0.0.00
BVC(%):100.00
89 _
NR
_
21.9
NR
-
37.6
NR
_
.49
90 58.7
47.2
-
_
_
fr. OLIVE WVF-
PERMIT CHRONIC LI.MrE:99%
'96
fPDESX: NN0203]5
PDESN:NOD0=
BcgW 2/1/88 Prague Q P/F
'8]
Canty: WAYN'E
Region: WARD
MmW:MAR IIIN SEP DEC
-88-
(PASS)
PP: 1.0
7Q10:0.000
IWC(%):I00.00
SOGJOC Pcq:
SOC:1027.7/88 NO TO%REQ
189 -
-
PASS
-
-
(PASS)
-
_
PASS
-
-
-
-
Na
PASS
-
-
PASS
90 -
-
M
PAIL
LATE
_
_
PASS
NRN(Y MEDICAL CF_v7PR
RESCNUED II/89
PDESA: NCDM8857
&girt I/1I88 H'^9 D
'86
Cowry: (}BROKFP
ftcgim:ARO
M-do: mW:FEB MAY AUG NOV
'98 '88 (NIT)
NONE-
PP:0.05
SOCAOC Req:
'89 -
NODE
(_)
-
(-)
Z3•
_
-
NR
NONE
7QI0:62.0
BVC(%):0.12
-
-
NONE
-
-
39.6
90
-
-
NR
0 2cmxm6vchd.x..,Wr mt nmmnpUwm Y 19836u.vd.bl.
LEGEND:
PPwPemdmd flow (MOD). 7Q10=Remiving room low now ai m(c[.),BVC%.Wae.mwun m00000'oim,Begin-F1m mmN xquixd. FmquorcyKMmlmrmg fxgrcrry): IQ.Qu. ,,,M-Min r,BM-BWaWdr, SA-semi.rmu,vy; A-gnvWly;
OWWD Ywl�n P gin Nohow 'eCeriode to,iPB mY oo oIo. I.C.M, V�Urmm l�cvo '1-.NuWi P..ncdc ookb 1.y, Aw ., Chr-Coo ic.A-qv ymmiwayk .x.mn ,upm ooy, SA-
(Repoti gNm6m): I._wD.n mt required, NR.Nm xpo d,( )wBag"e 9 of Qvurerl. IF.cdiry Aaivi�y5 n.); I I.Wniw, NwNewlyl ucd(Taccorve a).HrActi,�� Wt.0DRMd q &, p, bo-B.d xrtJ.
28
E

HAZEN AND SAWYER, P.c.
CONSULTING ENGINEERS
May 22, 1990
Mr. M. Steven Mauney
Water Quality Supervisor
N.0 Division of Environmental Management
8025 North Point, Suite 100
Winston-Salem Regional Office
Winston Salem, NC 27106
Re: Confirmation of Discussion on SOC for Mount Airy
Wastewater Treatment Plant Expansion
H&S No. 3975
Dear Steve:
This letter is to confirm our conversations with yourself and Trevor Clements
concerning the items to be incorporated into the SOC under discussion relative to
expansion of the Mount Airy wastewater treatment plant. We discussed the following
points relative to the SOC:
1. We are continuing to pursue data collection from the Bench Scale Pilot Plant to
model plant performance with increased flow from Cross Creek (Quality Mills).
Results to date suggest no difficulty in satisfying the acute toxicity limit.
However, we have not yet been successful in meeting the proposed chronic
toxicity requirement. At this point, we are inclined to believe that our problem
with the chronic toxicity test is more than likely related to the instability of the
bench scale plant and not necessarily an indication of effluent toxicity. We are
in the process of completing a third laboratory analysis scheduled for completion
on May 23rd. The stability of the bench scale plant was much improved prior
to taking this sample, and we are hopeful that we can demonstrate satisfactory
compliance with the proposed chronic limit. We understand that we must
demonstrate the capability to comply with the chronic limit as a precondition to
the SOC. We further understand that a single passing test will be acceptable to
DEM.
2. We discussed the period to be covered by the SOC and agreed that the SOC
would cover that period required for construction of the proposed plant
expansion. We anticipate an acute toxicity limit for the period of the SOC, and
we understand that DEM will also propose monthly chronic toxicity monitoring
for the period of the SOC. This monitoring will serve as an indicator of
possible plant performance after the expansion is complete and would allow for
preparation on the part of the City should it become clear that the completed
plant might have an ongoing chronic toxicity problem.
4= W/ESTCHASE SCULEVARD . SUrrE 550 . RAIEIGH, NC 27607 . [phone] FAX [phone]
R4.6GH. NC CHNLOTTE. NC NEWPORT NEWS. VA HOLLYWOOD, R NEW YOR, NY

Mr. M. Steven Mauney
May 22, 1990
Page Two
3. We have previously discussed the desirability of temporarily discontinuing
service to the existing aeration basin during the plant expansion. The current
bench scale work will produce data on anticipated plant performance without the
benefit of the aeration system. Your previous letter of January 24, 1990
suggested a seven -month allowable window from September 1, 1990 to April 1,
1991 for that portion of the construction that must be completed with the
aeration basin off-line. We have discussed this proposal both internally and with
the City and offer the following comments and suggestions:
a. A 7-month construction period is tight for the work required but should be
attainable if normal weather conditions prevail. The specifications would
require that the contractor restore service to one cell of the proposed two -cell
aeration basin during the stipulated time frame. Half of the proposed
aeration tank volume will be adequate for the initial flows expected at the
treatment plant.
b. Given the present status of the plans and specifications (submitted for
Division approval on May 4, 1990), it is doubtful if not unlikely that we can
have a contractor in place and prepared to undertake construction of a major
structure by September 1 of this year. Even assuming the most optimistic of
schedules, September 1 would be at the very beginning of the construction
process, and we are reluctant to require that such a major effort be forced
into the start-up of the project. Given the desirability and the Division's
preference for shutting down the aeration system during the cooler months of
the year, we suggest that the allowable window be moved into the second
winter season of construction or September 1, 1991 to April 1, 1992. Such
a time frame should be much more amenable to the anticipated pace of the
construction.
c. Relative to the above comment on schedule, there is also a need to consider
the effort required for sludge removal from the existing aeration basin.
Based on limited field sampling by the operating staff, we estimate that as
much as 2.5 million gallons of sludge exist within the existing basin and
must be removed prior to construction of the new aeration system. Given
our previous comment on the length of time required to construct the new
aeration system, we do not believe it is practical to remove the sludge within
the same 7-month window allowed for the new construction. We have
identified two alternatives that provide for sludge removal. These
alternatives are as follows:
(i) Alternative 1 - Increase the allowable window for decommissioning of
the aeration basin to 9 months (September 1, 1991 to June 1, 1992)
to allow additional time for sludge removal.
HAZEN AND SAWYER PC

Mr. M. Steven Mauney
May 22, 1990
Page Three
(ii) Alternative 2 - Allow the aeration basin to be taken off-line for up to
60 days during the initial 7-month window (September 1, 1990 to
April 1, 1991) to allow for sludge removal. The existing aeration
basin would be returned to service no later than April 1, 1991.
Decommission the basin a second time beginning on September 1,
1991 to allow for new basin construction. Since some additional
sludge would be expected to accumulate in the basin, we recommend
that the window be increased to 8 months, or May 1, 1992 to allow
for removal of any additional accumulated sludge as well as the
necessary construction. Under this alternative, the basin would be out
of service for a total of 10 months.
Since Alternative 1 minimizes the length of time that the aeration basin would
be out of service and only requires that the basin be dewatered on a single
occasion, we would prefer to handle the sludge in this fashion. We require
comment from the Division before we can make final provision for sludge
removal.
In addition to the above items, the City would also request that the SOC provide for
an interim flow increase up to 5.0 mgd as opposed to the 4.8 mgd previously discussed
The increase in permitted flow is desired to assure continued economic growth in Mount
Airy -
We will provide additional information on the results from the bench scale plant and
toxicity sampling as it becomes available. We would appreciate any comments from the
Division relative to our suggestions for items to be addressed in the SOC.
Very truly yours,
HAZEN AND ,� YER, P.C.
Oe(Donald L. Cordell, P.E.
Vice President
DLC:er
cc: Mr. Jerry E. Cox
Mr. Steve Tedder
Mr. Trevor Clements
HAZEN AND SAWYER, a.c.

® North Carolina Wildlife Resources Commission
512 N. Salisbury Street, Raleigh, North Carolina 27611, 919-733-3391
Charles R. Fullwood, Executive Director
MEMORANDUM
TO: Melba McGee, Planning and Assessment
Dept. of Environment, Health & Natural Resources
Resources
FROM: W. Don Baker, Program Manager a/'9 �
Division of Boating and Inland Fisheries
DATE: April 18, 1990
SUBJECT: Renewal and Modification of NPDES Permit and
Finding of No Significant Impact (FONSI) for City
of Mount Airy Wastewater Treatment Plant Expansion
to 7 MGD, Surry County, North Carolina.
We have reviewed the subject Environmental Assessment
(EA) and Finding of No Significant Impact (FONSI) regarding
the proposed improvements and permit renewal for the City of
Mount Airy wastewater treatment plant facility. Proposed
upgrading of the wastewater treatment plant includes the
following: 1) influent pump station modifications, 2)
screening and preliminary treatment facilities, 3) upgrade
of trickling filters, 4) intermediate pump station
modifications, 5) aeration basins, 6) new final clarifiers
with distribution box, 7) an additional chlorine contact
chamber and dechlorination and 8) post aeration facilities.
Sludge treatment facilities include a gravity belt
thickener, anaerobic digester modifications and a belt
filter press for sludge dewatering. Proposed treated
wastewater discharges will increase from approximately 4 MGo
to 7 MGD by the year 2000. Our comments are provided in
accordance with the State Environmental Policy Act (G.S.
113-A through 10). An onsite inspection was not conducted
for this report.
The Ararat River below the treated wastewater discharge
is a Class C stream containing both cool and warmwater fish
species. The FONSI notes that the receiving waters below
the current and proposed discharge at the confluence of
Lovills Creek and the Ararat River have a high assimilative
capacity which could handle the proposed 7 MGD discharge.
Due to the degraded water quality of Lovills Creek from
permitted wastewater discharges, storm water runoff,

Memo Page 2 April 18, 1990
nonpoint source discharges and improper land use practices,
it is doubtful that the Ararat River can assimilate as much
treated wastewater as proposed under the NPDES permit
without further degradation of downstream aquatic resources.
The high proportion of industrial waste versus residential
and commercial flows has the potential to increase the
presence of toxic materials, especially metals, in the.
Ararat River. The FONSI notes that concentrations for
cadmium, chromium, and copper, the metals considered most
significant in terms of potential impact on the treatment
plant and receiving waters are all within the range
considered acceptable for biological systems. This may be
true for this one facility, however, the cumulative effects
of toxic material discharges from additional point and
nonpoint sources needs to be addressed before allowing an
increase in wastewater discharges from this plant.
Nutrient input from treated sewage discharges on
benthic producer communities can alter their composition.
Algae populations, the base of the food chain, can be
changed from beneficial to harmful forms below nutrient
loading discharges, impacting consumer organisms. Ammonia
nitrogen and phosphates increase dramatically below treated
sewage discharges. These effluents reduce benthic algae
communities, often resulting in a shift away from diatoms,
the preferred food of many invertebrate grazers. Biological
changes at the base of the food chain which occur below
effluent discharges often lead to corresponding changes
(reductions) in the populations of consumer organisms
(invertebrates and fish). These changes in aquatic habitats
are often subtle and can go unnoticed to the casual
observer. Additional nutrient loading on an already
degraded aquatic resource, the Ararat River, needs to be
addressed. The. Division of Environmental Management should
seriously consider the impacts of this facility on the
aquatic community downstream and strive to improve the water
quality of the river and aquatic resources. The Ararat
River, if its water quality were to improve, could once
again become a high quality smallmouth bass stream.
The Ararat River is considered a cool water stream in
the vicinity of the treatment plant capable of supporting
smallmouth bass. The issue of temperature increases on
receiving waters and aquatic resources below the effluent
discharge has not been addressed.
The FONSI does not address the color of the permitted
wastewater discharge. Due to numerous textile mills in the
area, effluent from this plant is usually a dark dye color.
This color discharge can interfere with light penetration
through water, thereby reducing natural biological processes
and aquatic resources even further.

Memo Page 3 April 18, 1990
The FONSI (Figure 1) alludes to the proposed
construction of a gravity outfall transmission line,
regional sewage lift station, and forcemain transmission
line paralleling Stewarts Creek and the Ararat River. No
plans were given for their construction or mention made on
their impacts on wildlife, fishery resources, or wetlands.
The construction of these items will impact wetlands,
floodplain areas, stream riparian zones, and possibly
bottomland hardwood forests. This phase of the project has
the potential to impact species considered endangered,
threatened, or of special concern under the State Endangered
Species Act (G.S. 113 Article 25). Species found in the
area include the mole salamander, four -toed salamander and
bog turtle.
Based on review of the plans submitted and WRC concerns
listed above, we approve of the plans with the following
modifications:
1. Further study be given to cumulative effects on
NPDES discharges and nonpoint discharges on the
Ararat River and Lovills Creek water quality. The
proposed treatment plant nearly doubles (4 MGD to
7 MGD) the permitted wastewater discharge. Just
how much waste can the Ararat River assimilate
before irreversible damage to aquatic resources
occurs needs to be addressed.
2. The issue of water temperature increases from this
plant on cool water habitats needs to be
addressed.
3. The color of the effluent discharge should not
alter the water color of the receiving stream
(Ararat River).
4. WRC approval of the enclosed plan does not
constitute endorsement of construction of the
gravity outfall transmission line, regional sewage
lift station, or forcemain transmission line. We
will need to review these plans upon their
completion.
5. Plans submitted for item four above should address
mitigation to off -set impacts to wildlife and
fishery resources, note wetlands to be impacted,
and address the issue of endangered species.
Thank you for the opportunity to review and comment on
this project. If we can provide further assistance, please
call on us.
DB/lp
cc: Don Hayes, District 7 Wildlife Biologist
Joe Mickey, District 7 Fisheries Biologist
John Fridell, USFWS, Asheville

C;
HAZEN AND SAWYER, P.c.
NIAR 3 0 199r, 0 CONSULTING ENGINEERS
• ltt:t ,:ti .j: s 'u",;
1 March 2r; 1990
MAR' 0s
Mr. Steve Tedder_" e ¢a��^ Qa 199r
Chief of Water Quality Section � 1! i_ � �;��,_•,; ;�
Division of Environmental.Management
Department of Environment, Health MAR 3 0 i990 '^
and Natural Resources
P.O. Box 27687 Iti,i,lpvgl;li fU�( iS�hP,CH
Raleigh, NC 27611-7687
n
Dear Mr. Tedder: I
We have been corresponding with Steve Mauney in the Water Quality
Section of the DEM Winston-Salem office regarding a schedule for compliance
for the City of Mount Airy Wastewater Treatment Plant Expansion. A specific
area which we are trying to resolve in the near future is_a proposed
requirement for a treatability study to evaluate conditions of future
operation. We have discussed these conditions and proposed testing approaches
with Steve Mauney and, at his suggestion, have summarized our recommendations
in this letter as follows.
Condition during construction for interim increase in flow from
Cross Creek Mills (formerly Quality Mills) when aeration -basin is
removed from service for modification to an activated sludge
configuration. During this period, secondary treatment will be
provided by existing trickling filters which will remain in
service. It is anticipated that polymer feed can be provided
during this period in order to improve settleability and offset
the loss of the aeration basin. An interim limit for acute
toxicity has been proposed for an In -stream Waste Concentration of
36 percent at a plant flow of 4.8 mgd.
General Testing Approach: The existing plant has capability for
varying flow split between trickling filters and has even
successfully operated at higher loadings that occur with one
filter out of service. This capability will be used to increase
loading on one of the trickling filters to simulate the interim
loading condition. Bench -scale evaluations of polymers will then
be performed on the effluent from this trickling filter to
evaluate the need for supplemental treatment.
Future condition when Cross Creek Mills has completed its
expansion, thereby increasing its percentage of wastewater input.
This will be the most critical condition that should cover the
full range of incremental changes anticipated for Cross Creek
Mills.
4000 WESTCHASE BOULEVARD . SURE 550 . RAL.EIGH, NC 276D7 . [phone] FAX [phone]
RALErK NC CKVXDTrF NC NEWPORT NEWVA HOLLYWOOD. FL NEW YORK NY

Mr. Steve Tedder
March 22, 1990
Page Two
General Testing Approach: Because of difficulties in satisfactory
pilot testing and logistical problems in obtaining the large
volume of feed flow from Cross Creek Mills as would be needed for
simulating an adequately sized trickling filter pilot plant, we
have recommended an approximation of the future condition using
effluent from the existing trickling filters to simulate the
background flow to which additional Cross Creek Mills effluent
will be added. The added increment of Cross Creek Mills effluent
will be collected and fed to the pilot plant as a supplemental
feed stream without the benefit of prior treatment by trickling
filters. Therefore, a somewhat conservative condition will be
represented in these tests and actual plant performance should be
better than this simulation. However, significant variation is
not anticipated since most of the pilot plant influent will be
comprised of base flow that has received trickling filter
treatment. The pilot —scale unit is a basic activated sludge
system that simulates future operating conditions, particularly
with respect to detention time and sludge age.
Testing will be performed to determine the effects of future treatment
conditions. In the case of the interim condition during construction, acute
toxicity will be evaluated. Chronic toxicity will be evaluated for the future
condition with increased Cross Creek Mills effluent. Both sets of toxicity
tests will be performed for a range of dilutions so that the effects of
treatment can be more clearly delineated than with pass/fail tests at fixed
dilutions. Other parameters to be evaluated at the influent and effluent of
testing include:
BOD5
SS
pH
Temperature
Ammonia
Dissolved oxygen.
We will contact you in the near future to see if there are any
additional comments. In the meantime, if we can answer any questions, please
let us know.
Very truly yours,
HAZEN AND SAWYER, P.C.
George C. Budd, Ph.D., P.E.
Associate
GCB:er
cc: Mr. Steve Mauney
HAZEN AND SAWYER, P.c

a
State of North Carolina
Department of Natural Resources and Community Development
Winston-Salem Reg onal Office
James G. Martin, Governor William W Cobev Jr, Secretary
DIVISION OF ENVIRONMENTAL MANAGEMENT
January 24, 1990
030­103
Suva+�vev
Mr. Jerry E. Cox, City Manager
City of Mount Airy
P. O. Box 70
Mount Airy, NC 27030
`J2N ', i 1990
SUBJECT: Preliminary Schedule of
Compliance Outline TEGPti ,;,
City of Mount Airy WWTP Expansion", -n1
NPDES No. NCO021121 i
Surry County �?
L
Dear Mr. Cox:
As you are aware, the Water Quality Section of the
Winston-Salem Regional Office was directed to provide the
City with certain conditions which are expected to be
contained in any formal Schedule of Compliance which mav be
submitted to the Environmental Management Commission for
approval. The majority of the conditions were discussed in
Raleigh at the meetings on December 6, 1989 between agents
of the City and D.E.M. The specific issues which are likely
to be incorporated into the Order are as follows:
1) Toxicity -
During the period within which the S.O.C. is in
effect, an interim limit for acute toxicity will
be established.
This limit will be set at the projected In -stream
Waste Concentration, which is 36% at 4.8 million
gallons per day, The effluent must exhibit no
acute effect at the I.W.C. The tests must be done
monthly, such that any failing trend can be
quickly identified, and appropriate steps to
address the problem can be initiated.
8025 North Point Boulevard, Suite 100, Winston-Salem, N.C. 2710G3295 • Telephone [phone]
An Equal Opportunity Affirmative Action Employer

Jerry E. Cox
Page �,2
January 24, 1990
Additionally, influent sampling for the presence
of previously banned surfactants should be
initiated immediately. The sample ,should be of
the composite type, and should be collected
weekly. Reduction of this frequency:will be
considered upon confirmation of the absence of
banned surfactants. Should the sampling confirm
the presence of surfactants, steps listed as
"Phase I" on page 2 of the October 3, 1989 Hazen
and Sawyer letter should be initiated in order to
pin -point the offending Industrial User.
It is also relevant to note that construction of
dechlorination facilities may favorably impact the
toxicity problem.
2) Treatability Study
Because the projected (and in fact, current)
volume of industrial flow contributed to the plant
is substantial in comparison to the sanitary waste
flow, and because textile waste has been shown to
have contributed to past effluent toxicity at the
plant, treatability studies should be submitted
with each request for incremental flow increases,
including the initial request. The treatability
studies should reflect the conditions anticipated
during the interim period of plant expansion,
such as decreased oxygen values when the aeration
basin is taken out of service.
The management of Quality Mills should be required
to furnish precise information as to the quantity
of waste -water flow including anticipated flow
patterns both daily and weekly, waste -water
characteristics with anticipated hourly and daily
variations from the norm, and any proposed
pretreatment facilities.
When the treatability studies during interim
conditions have been completed, simulating
anticipated circumstances as closely as possible, a
study can then be performed which simulates
as -built conditions.

Mr. Jerry E. Cox
Page #3
January 24, 1990
3) Construction phasing
As you are aware, the Division would prefer that
any activity resulting in a temporary decrease in
oxygen transfer to the waste -water (such as
circumventing the aeration basin) be carried out
in cold -weather months, due to increased flows and
higher ambient D.O. levels in the receiving
stream. The basin should not be taken out of
service prior to September 1, 1990, thus delaying
this period of potential plant upset beyond the
critical stream flows of the summer season. It
must be back on line no later than April 1, 1991,
so that the modifications will be accomplished
prior to the addition of a majority of the
inndustrial flow. Regardless of the timing of
construction, certain steps can, and
and should, be taken to minimize the effects of
loss of the aeration basin.
These steps should include construction of an
effluent aeration unit at the outfall, or an
alternative means of providing supplemental oxygen
to the waste -water. If the City does not choose
to construct the post aeration facilities in the
initial phases of construction ,then data should
be provided to support any short-term alternatives
which may be considered, such as placement of a
mechanical aerator or aerators in existing units.
Additionally, due to anticipated regulatory
changes relative to disinfection, it would likely
be economically favorable for the City to initiate
construction of the dechlorination units while
modifications to the chlorination units are
underway.
4) Interim (S.O.C.) Limits and Schedules
Until data is produced from the treatability
study, any limits proposed for Biochemical Oxygen
Demand would be arbitrary, since the critical
problem involves the ability to provide oxygen
transfer while the existing aeration basin is out
of service.

Mr. Jerry E. Cox
Page #4
January 24, 1990
Other limits which can be anticipated in the
S.O.C. are as follows:
A. Dissolved Oxygen - 5 mg/l
B. Fecal Coliform - 1000 colonies/100 ml
C. Toxicity - No acute effect at 360
D. Total Suspended Solids - limit will be
established based on data from treatability
studies.
Likewise, the dates in the Schedule can be better
arrived at following finalization of construction
plans. Please provide the treatability and
construction information as soon as possible, so
details of the S.O.C. can be arrived at with
minimum impact on construction start-up.
Should you have questions on this matter, please
contact me at [phone].
Sincerely,
M. Steven Mauney
Water Quality Supervisor
MSM/vm
CC: Hazen and Sawyer
Steve Tedder
%Trevor;Clem'erits
Central Files
WSRO

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DIVISION OF ENVIRONMENTAL MANAGEMENT
December 7, 1989
MEMORANDUM
To: Mount Airy WLA File
From: Trevor Clements
Subject: December 6 Meeting with Mount Airy Representatives
DEM Water Quality staff from the Winston-Salem Regional Office
and Central Headquarters met with representatives of the City of
Mount Airy (see attached attendance list) to discuss issues
surrounding the expansion of the City's existing wastewater
treatment plant (WWTP). Discussion centered around the steps
that Mount Airy must take in order to receive approval from DEM
for the addition of industrial sources of wastewater during the
expansion process while under a Consent Order. The Division is
concerned with numerous toxicity test failures that have
occurred at the Mount Airy facility within the past year, and
the additional effect that increased wasteflow from Quality
Mills (a Significant Industrial User within the City's sewer
system) may have on the facility's Pffluent toxicity.
During the meeting, the City and their consultant (Hazen &
Sawyer) were asked to explain what actions were being taken to
address the toxicity problem. The City replied that increased
testing had been performed, including split sampling with
independent certified toxicity laboratories. However, no
toxicity reduction efforts had taken place since the City had
passed its last 3 tests. Regional DEM staff presented Mount
Airy with data collected by DEM showing test failures for two
samples collected in late October and November of this year.
Staff from each party agreed to share data for further
examination of whether a problem continues to exist with regard
to effluent toxicity.
The City's consultant indicated they hoped to begin construction
of their new facility in July of 1990. During construction, the
City plans to take their aeration basin out of service for about
six months while plant renovations occur. At this time,
treatment will consist only of trickling filters. DEM expressed
a preference to delay this action until September to avoid the
warmest summer months, as plant BODS is expected to be between
50 and 60 mgil during this interim phase. Also, DEM recommended
that measures be implemented to obtain an effluent DO of at
least 5.0 mgil prior to decommissioning of the aeration basin.
Mount Airy will likely construct a stepped, cascading outfall to
fulfill this requirement.

{
Other items discussed included performance of a treatability
study on Quality Mills' existing effluent, and the
implementation of dechlorination. The Section chief also
mentioned that the City of Mount Airy should seriously consider
providing sewer service to nearby residential areas that are
experiencing subsurface system failures. DEM staff generally
concurred that the additional domestic waste source may benefit
plant operation given that the influent is dominated by
industrial sources. The Winston-Salem Regional Office agreed to
follow up the meeting with a letter to Mount Airy detailing the
Division's position and outlining the necessary components of
the warranted Consent Order. Technical Support will assist the
region by performing an instream assessment as soon as the
appropriate information is submitted.
TCiam
CC: Steve Tedder
Steve Mauney
Ken Eagleson

^nun� n
SUBJECT PROJECT: ¢" I.J
PROJECT NO.
CONFERENCE DATE: 12./(o 69
—I I
BRIEF PURPOSE OF CONFERENCE:
ATTENDEES:
REPRESENTING
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Nate : `TGAC-1f, (Z� P by 5� � � -7-Year- Cla .
State of North Carolina
Department of Natural Resources and Community Development
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Governor R. Paul Wilms
William W. Cobey, Jr., Secretary October 24, 1989 Director
Mr. Gordon C. Ruggles, P.E.
Senior Vice President
Hazen & Sawyer, Consulting Engineers
4000 West Chase Blvd. Suite 550
Raleigh, NC 27607
SUBJECT: City of Mount Airy WWTP
NPDES Permit NCO021121
Surry County
Dear Mr. Ruggles:
This correspondence is in regard to your letter of
October 3, 1989.
As you are aware, the City of Mount Airy failed its
toxicity tests for January, April, May and June 1989. The
toxicity tests passed in July, August and October, but the
July test was apparently conducted during a shut down period
for some of the indirect sources, and would therefore not be
representative.
A review of the capacity of the treatment units
indicates that the existing facility should have the
capability to meet secondary limits at 4.8 MGD with a
domestic strength influent. However, for the period
beginning September '88 until August 189 the effluent BOD of
21 mg/l and TSS of 20 mg/l were achieved while the flows
only averaged 3.3 MGD. Admittedly, the plant performed
slightly better than this during June and July '89 when the
flow was 4.1.MGD, but the data shows this plant does not
operate as well during the colder months of the year. Also
the addition of 0.5 MGD or more of industrial wastewater
could change the strength of your influent waste and degrade
the effluent quality.
It appears that portions of the first phase upgrading
identified on page 17 of the "Supplemental Report, Water and
Wastewater Systems Evaluations" dated November 1988, would
Pollution Prevention Pays
P.O. Box 27687, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

Gordon C. Ruggles
Page #2
October 24, 1989
be necessary to insure compliance at 4.8 MGD. An item that
certainly will be important at this higher flow is the
upgrading of the aeration basin. It is suggested that Mt.
Airy authorize your firm to proceed to finalize plans for
this first phase upgrading and submit them in the near
future. This should be done quickly so that, upon approval
of plans, this portion of the project can proceed. Any
other portions of the first phase upgrading that you feel
are essential to achieving compliance at 4.8 MGD should be
included in the plans.
The request for Special Order dated October 11, 1989,
from Mr. Jerry Cox, City Manager, Mount Airy has been
received. We plan to direct our Winston-Salem Regional
Office to proceed in developing a short term Special Order
by Consent. The Order will not allow any industrial waste
increase unless it is shown to be equivalent to domestic
wastewater. Mt. Airy must provide a schedule to renovate
the aeration basin initially. While the SOC is being
processed, Mt. Airy should submit a NPDES modification
request for an interim flow of 4.8 MGD or that flow which
will be needed until the upgrading to 7.0 MGD is completed.
We can verify what limits will apply at that flow and
reissue the permit with the revised limits which will be
slightly less stringent than at the permitted flow of 7.0
MGD. When renovation of the aeration basin is completed and
the City achieves final limits that apply at the interim
flow, the SOC could be voided. At that point, Mount Airy
can accept additional industrial flows that are compatible.
The toxicity limit will be in effect and enforced except for
the life of the SOC.
It is suggested that the City begin immediately to
conduct a toxicity treatability study on the type of
additional wastewater flow expected from Quality Mills.
You indicated that Mount Airy would need about 6 months to
conduct a phase 1 data compilation of a toxicity reduction
evaluation. It is felt that four (4) toxicity failures in
1989 are enough reason to proceed with that study now. With
regard to the permit condition on expansion to 7.0 MGD and
compliance with whole effluent toxicity limitations, I must
add to my comments in the letter dated August 28, 1989, to
Mr. Jerry Cox. My decision to withdraw the permit clause
will be based on the city's commitment to submit a treat -
ability study on Quality Mills additional waste data
compilation for toxicity reduction. The SOC will have a
schedule for these item.

Gordon C. Ruggles
Page #2
October 24, 1989
Your suggestions for an SOC schedule
appreciated. If you have any questions on
not hesitate to contact Trevor Clements at
Steve Mauney at [phone].
Sincerely,
will be
this matter, do
[phone] or
R. Paul Wilms
Director
cc: Mr. Jerry Cox
Mr. Trevor Clements
Mr. Dale Overcash
Mr. Steve Mauney
Central Files

HAZEN AND SAWYER, P.c.
O CONSULTING ENGINEERS
t
October 3, 1989 �.
RU„ 4 L
Mr. R. Paul Wilms OU 13A989,
Director
North Carolina Division of TECHNICAL SUPPORT BRANCH
Environmental Management
P.0_ Box 27687
Raleigh, NC 27611-7687�
Re: City of Mount Airy WWTP ttt
NPDES Permit No. NCO021121
Whole Effluent Toxicity Limits
Dear Mr. Wilms:
We have been authorized by the City of Mount Airy to present technical
approaches for resolving whole effluent toxicity and other issues related to
expansion of the Mount Airy Wastewater Treatment Plant. The City has an
interest in working with the Division of Environmental Management in resolving
these issues under an alternative that does not pre —condition a permit for
plant expansion on achieving compliance with whole effluent toxicity.
Although it is concerned about the potential for whole effluent toxicity at
its wastewater treatment plant, the City will need time for further study to
allow it to deal with the problem. In the meantime, decisions must be made
relative to commitments for substantial industrial expansion within the City.
Given the circumstances, the City feels that a Special Order of Consent
approach would be a more suitable alternative for dealing with this issue.
In the past, the Mount Airy Wastewater Treatment Plant has experienced
several distinct trends in effluent toxicity as indicated by the Ceriodaphnia
chronic effluent bioassay procedure. From February, 1987 through July 1988,
the effluent passed 6 of 7 quarterly tests. The single failed test occurred
in March, 1988. Three quarterly tests in a row were then failed for a period
from October, 1988 through April, 1989 when monthly testing was initiated.
Monthly tests for May and June also failed. However, the most recent tests in
July and August suggest that a passing trend may have been re—established.
Reasons for the variations in trends have not been determined and will
require monitoring before assessments can be made. Additionally, proposed
plant modifications will improve treatment and may alter these trends. To
address these two aspects of effluent toxicity, the following steps can be
taken by the City under the Special Order of Consent:
400D WESTCHASE BOULEVARD . SURE 550 . RALEIGH, NC 27607 . )919) 833-7152 FAX )919) B33-1828
RALBGK NC CHAiLOTTE NC NEWPORT NEWS VA HOLLYWOOD, FL NEW YONK NY

Mr. R. Paul Wilms
October 3, 1989
Page 2
Perform a follow—up monitoring program as a continuation of
toxicity evaluations originally performed by Burlington Research,
Inc. in May, 1986.
Perform pilot plant testing to assess the effect of proposed plant
modifications on effluent toxicity.
If a failing trend becomes re—established, additional steps can be taken
under a phased toxicity reduction evaluation that could be initiated upon
notification of the City by the Division of Environmental Management of a need
to proceed with this program. Phase 1, the initial data compilation phase of
the program, could proceed immediately upon notification and could be
completed within 6 months of the notification date. This phase would consist
of data collection of chemical usage by industries with assessment of
potential toxicological properties and detailed review of possible
relationships between operating/performance characteristics at the WWTP and
effluent toxicity. Based on the results of Phase 1, tasks and schedules for
any subsequent phases of evaluation will be developed for review and approval
by the Division of Environmental Management.
If the proposed pilot testing program indicates a potential for
substantial improvement in effluent toxicity upon completion of the proposed
plant upgrade, toxicity reduction evaluations would be deferred until the
upgrade has been completed. Under this condition, there would be limited
value to performing toxicity evaluations for the interim conditions that would
occur prior to upgrade.
Under the Special Order of Consent, the City of Mount Airy would also
need variances from the existing permit limitation of 4.0 mgd on a maximum
monthly basis to a revised interim limit of 4.8 mgd until the plant can be
fully upgraded. These increases are needed to accommodate ongoing industrial
expansion that is vital to economic growth both within the City and this
region of North Carolina. To date, the plant has treated maximum monthly
flows up to 4.1 mgd in conformance with effluent requirements of the existing
permit. It was originally designed for a much higher organic loading
(375 mg/l BOD5 for design vs. existing BOD5 of 224 mg/1) than is presently
being experienced and evaluations of unit hydraulic loadings indicate they can
also be maintained within desirable ranges as indicated by the following:
Unit Process Hydraulic Loading at 4.8 mqd
Primary Clarifiers 600 gpd/sq.ft. (with 3 mgd recycle)
Aeration Basin 2.1 days detention
Secondary Clarifiers 630 gpd/sq.ft.
Chlorine Contact Basins 41 min. detention
HAAZENN AND SAWYER P.c

Mr. R. Paul Wilms
October 3, 1989
Page 3
If necessary, polymer feed can be added to the aeration basin effluent
to improve settleability in the secondary clarifiers. Hydraulic improvements,
primarily in the form of increased capacity for the raw sewage and
intermediate pump stations, would be required to accommodate the increased
flow for this interim time period.
Also, as a part of the Special Order of the Consent, planned
modifications for upgrade of the aeration basin can proceed most efficiently
if the existing basin can be removed from service for an interim construction
period (perhaps 4-6 months). During this period effluent would still receive
secondary treatment on the trickling filters and settleability could be
enhanced by polymer addition. However, some excursion in effluent quality
beyond permit limits may occur under this interim construction condition.
Interim limits based on the treatment levels obtainable with trickling filters
would be appropriate.
Please let us know if we can answer any questions.
Sincerely,
HAZEN AND SAWYE P.C.
d
G rdon Cice— resiRu es, P.E.
Senior Vdent
GCB:er
cc: Mr. Jerry Cox
Mr. Trevor Clements
Mr. Dale Overcash
Mr. Steve Mauney
HAZEN AND SAWYER PC

J
DIVISION OF ENVIRONMENTAL MANAGEMENT
September 26, 1989
MEMORANDUM
TO:
Steve
Tedder
FROM:
Trevor
Clements S
SUBJECT: Meeting with City of Mount Airy
A meeting was conducted on September 20th with representatives of the City
of Mount Airy and their consultant, Hazen & Sawyer, to discuss the City's con-
cern over the condition in their NPDES permit that requires compliance with the
whole -effluent toxicity requirement prior to expansion of their wasteflow. The
City of Mount Airy plans to expand from 4.0 to 7.0 MGD, with the major source of
additional wasteflow expected to come from Quality Mills, a textile corporation.
Mount Airy officials would like to have the toxics condition deleted from their
NPDES permit. The City would also like to have DEM increase the design capacity
rating to handle first phase expansions of Quality Mills (approx. 0.5 MGD) using
the existing treatment facility. DEM staff want assurances that appropriate
steps are being taken by Mount Airy to address their current toxicity problem
(testing record attached) before potentially adding to this problem with
expanded sources of industrial wasteflow.
Available options to Mount Airy were discussed. DEM staff recommended that
Mount Airy perform a treatability study on the additional wastestream to be
added by Quality Mills. It was also recommended that the City begin testing at
their future instream waste concentration (IWC) to determine whether the City
can expect to be in compliance upon expansion. Mount Airy was advised to submit
the necessary information for DEM to evaluate a change in the design flow
capacity rating as soon as possible. Alternatively, the City was told it could
pursue a Special Order for this interim flow increase to provide legal relief
from the toxicity permit requirement. However, DEM staff pointed out the poten-
tial for the State to withhold approval of a flow increase for industrial type
waste during the effective period of the Order unless it could be demonstrated
that the toxic substance concentrations of the additional industrial wastewater
were not significantly different from those associated with domestic wastewater.
It was made clear that Mount Airy would like an administrative answer to
this latter issue. If industrial source flow increases would not be allowed
under an Order, then the City will probably not want to pursue this avenue.
You, Dennis Ramsey, Steve Mauney, and myself should discuss this matter at your
earliest convenience.
Please let me know if further information is required.
cc: Tom-Stockton-1
Ken Eagleson
Dennis Ramsey
Steve Mauney

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State of North Carolina
Department of Natural Resources and Community Development
Division of Environmental Management
512 North Salisbury Street • Raleigh, North Carolina 27611
James G. Martin, Governor R. Paul Wilms
William W. Cobey, Jr., Secretary Director
August 28, 1984
Mr. Jerry Cox, City Manager
City of Mt. Airy
P.O. Box 70
Mt. Airy, North Carolina 27030
Subject: City of Mt. Airy WWTP
NPDES Permit No. NCO021121
Whole Effluent Toxicity Limits
I am writing in response to your letter sent June 7, 1,989, concerning the NPDES
permit conditions regarding design capacity expansion and compliance with whole -
effluent toxicity limitations. Efforts.i.n resolving your facilities effluent
toxicity are evident.
The qualifying condition in Limitation Chart A was not intended to preclude
expansion of the facility, but rather, states that upon expansion of the facil-
ity, the City must demonstrate progress in toxicity reduction prior to accepting
increased flow. The Division will consider deleting the qualifying phrase on
the permit if the City agrees to enter into a Consent Order with a schedule for
compliance with the whole -effluent toxicity limits. Under the order, flow addi-
tions will be restricted to domestic wastewater until compliance with whole -
effluent toxicity limit is consistently achieved. For the purpose of evalua-
tion, this will mean achieving a "pass" result on 3 consecutive toxicity tests
taken not less than one month apart.
I hope that this letter adequately addresses your concerns. However, if the
above decisions are unacceptable to you, you have the right to an adjudicatory
hearing upon written request within thirty (30) days following receipt of this
letter. This request must be in the form of a written petition, conforming to
Chapter 150B of the North Carolina General Statues, and filed with the Office of
Administrative Hearings, Post Office Drawer 11666, Raleigh, North Carolina
27604. Unless such a request is made, this decision is final and binding.
Pollution Prevention Pays
P.O. Box 27697, Raleigh, North Carolina 27611-7687 Telephone [phone]
An Equal Opportunity Affirmative Action Employer

If.you have any questions or comments regarding this matter please contact
Mr.Trevor Clements or Mr. Dale Overcash from my staff at [phone].
inc e ,
R. Paul Wilms
cc: r-Trevor--Clements
Dale Overcash
Steve Mauney
Central Files

NORTH CAROLINA DEPARTMENT OF NATURAL RESOURCES bFI5
COMMUNITY DEVELOPMENT'
DIVISION OF ENVIRONMENTAL MANAGEMENT �ECEI Dt-j¢
Winston-Salem Regional Office 04
JUL 1989
July 10, 1989
PERMITS &EN�,RINL=,_RI
M E M O R A N D U M
TO: Arthur Mouberry, Permits & Engineering
THROUGH: Steve Mauney, WSRO Water-Quality.Supervisor
FROM: Abner Braddy, Environmental Technician
SUBJECT: City of Mt. Airy 89/06/07
Letter to Paul Wilms
Draft NPDES #NC0021121 (Expansion)
Mt . , Airy WWTP
Su.rry County
We have reviewed the subject letter and offer the
following comments:.
1. The subject permit application requested
modification to the existing permit for upgrading
and expansion of the facility from its•present"4.0
MGD capacity to an eventual capacity of 7.0 MGD.
It is our understanding that the bulk of any
permitted flow increase would be -to accommodate a
local textile manufacturer, Quality Mills, Inc.,
with expansion plans which would result in an
additional 2.0 MGD of influent"to the P.O.T.W: It
is also our.understanding that Quality Mills, Inc.
is at present the largest Industrial User
tributary to the facility, supplying.approximately
1.1 MGD of the 3.1 MGD average daily flow
currently treated by the facility
2. The facility failed the last three (3) chronic
toxicity tests, in January, April, and May of
1989. Since the proposed increase in flow would
raise the facility's In -Stream Waste Concentration
from 32% to 420, any existing impact to the
receiving waters would be magnified, given a
static percentile of plant efficiency. The Region
feels that it would be imprudent to allow a major
increase of industrial flow to become tributary to
the plant prior to resolving the current toxicity
problem.

a f d
f'
`a Arthur Mouberry
Page _# 2
July 10, 1989
3. We do not dispute the city's contention that past
actions on their part have resulted in apparent
toxicity reductions. As noted previously,
however,,the problem, has begun to recur. The past
successes achieved"do`arot have a direct bearing on
the current problem..
4. The wording in Limitation Chart A does not state
that the "proposed expansion project is hinged
upon'resolution of the chronic toxic situation.'
Nothing in the wording precludes expansion of the
facility, but rather�,.-states that upon expansion
of the facility,"the City must demonstrate
progress in't�oxicity reduction,rprior, to accepting
increased. flow.. As "ther-,life of the project is
estimated` by the City' sv, engineers" to be. thirty to
t*hi rty`''six:months, we see`no reason that 'a
thorough T.R'E: cannot proceed jointly>w th the
plant expansion.,- During the expansion,.when
components 'of the .plarit become functional,
incremental flow increases 'could be considered if'
toxicity;. -reduction.: is. demonstrated.,,_
5. As,toxicity monitoring requirements are contained
in s the ' facility' s current.. NPDES­:tpermit ( reopened
June 1, 1987), and as the facility'is not meeting
conditions which constitute a successful test, the
facility is technically in non-compliance with its
existing permit. Issuance of the draft permit.
as is, therefore, would not impact the facility's
compliance status:

CITY OF MOUNT AIRY
o. &. 70
Cnrolint( 27030
Mr. R. Paul Wilms, Director
Water Quality Section
NC Department of NRCD, DEM
512 North Salisbury Street
Raleigh, NC 27611
Dear Mr. Wilms:
June 7, 1989
I am in receipt of NPDES Permit NNCO021121 and after reviewing it with
nw staff, I respectfully make comment on the following:
Limitation Chart A: It appears that our proposed expansion project is
hinged upon reso ution of the chronic toxic situation at our facility.
Mount Airy has been involved for some time with toxic reduction evaluations.
We were one of the first municipalities to have substantial reduction in
static toxicity due to the deletion of certain compounds from our waste
system (LC50 21.43% on June 26, 1986 to LC50 90% on July 31, 1986.) Volun-
tary chronic toxicity testing was started on October 29, 1986 and continued
through June 17, 1987 with five (5) evaluations passing and two (2) evalua-
tions failing. In July 1987, quarterly testing was added to our permit.
Since that time, nine evaluations have been conducted with four (4) passing
and five (5) failing.
Given the above information, I think that .the City's stance on the toxics
issue is clearly defined. We intend to exercise every option available, as
before, to clear up any problem that we may encounter in the future. In
light of these facts and after consulting with plant personnel, our consulting
engineering firm, and the commercial laboratories involved.with chronic
toxicity TRE's, we7�:rerpectfullly-request--that the: word ing>with, :regard.,_to:,:the-
toxicityjss&e_be'structured:'in`a:.way.,:that will not::require-it'to be=resolved
prior to plant expansion ---nor 'placethe=City 1 ninon -compliance as="long'as'
efforts=are'berng`made to-resolve`th'is issue;.
Thank you for your assistance and consideration in this matter.
JEC/db
xc: Mr'. Arthur Mouberry
Mr. Steve Mauney, Regional
Mr. Abner Braddy, Regional
Mr. Gordon Ruggles, Hazen
Sincerely,
ry E .
'ty Mana
Office RECEIVED
Office
Sawyer JUIV 16 1989
PERMITS & ENGINEERING

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