Memorandum
Date: November 29,2022
To: Administrative Record - Sac and Fox Meskwaki Nation WWTF and PWTF
Cc: Project File
From: Gerald H. Memming
RE: Waste Load Allocations - Sac and Fox Meskwaki Mechanical WWTF Outfall 00 land Public Water Treatment Facility Outfall 003
Waste load allocations (WLAs) and permit limits were calculated for ammonia for the above referenced WWTF and for total residual
chlorine (TRC) for the Public Water Treatment Facility (PWTF). Below are the assumptions used in the calculations and the
resulting limits.
Receiving Stream Flows
Outfall 001: Mechanical Treatment Facility - Treated Effluent
Flow data from Richland Creek, USGS gage 05451900 located near Haven, was used to estimate the flow of the unnamed tributary
(locally known as Onion Creek), which the facility discharges to. The area for the Richland Creek watershed is 56.1 square miles.
USGS gage 05451900 lias 73-year flow record collected from 1949 to the present. The Onion Creek watershed is 5.51 square miles.
Therefore, their watershed ration is 0.0982 (5.51/56.1). For the calculated acute and chronic low flow values for Onion Creek, refer
to the table below.
Season
Onion Creek
30Q10 (cfs)
7Q10 (cfs)
1Q10 (cfs)
Spring
0.3949
0.1882
0.1304
Summer
0.0895
0.0386
0.0230
Winter
0.0527
0.0326
0.0186
There is potential recreational use and/or fishing in Onion Creek.
Outfall 003: Public Water Treatment Facility - Backwash Wastewater
Flow data from the Iowa River at Marshalltown, USGS gage 05451500, and Timber Creek near Marshalltown, USGS gage
05451700, were added together and then multiplied the flow with an area ration (1880/1650). The drainage area of the Iowa River
above Outfall 003 is 1880 square miles and above USGS gage 05451500 is 1532 square miles. The drainage area above USGS gage
005451700 on Timber Creek is 118 square miles. For the calculated acute and chronic low flow values for the Iowa River, refer to
the table below. To be protective of downstream users, a mixing zone equivalent to IDNR's was used to develop the WLAs for total
residual chlorine (TRC). Based on a November 11,2020 of Iowa Wasteload Allocation (WLA) Procedure, the zone of initial dilution
(ZID) is limited to 2.5% of the 1Q10, and the chronic mixing zone is limited to 25% of the 7Q10.
Season
Iowa River
30Q10 (cfs)
7Q10 (cfs)
1Q10 (cfs)
Early Life Stages Present
(March 1 - September 30)
89.57
64.56
56.19
Early Life Stages Absent
(October 1 - Februaiy 28 [29]
53.72
42.31
39.54
Water Quality Standards
Outfall 001: Mechanical Treatment Facility - Treated Effluent
The facility located within tribal boundaries discharges to Onion Creek that does not have a designated use classification. To be
protective of the Clean Water Act 101(a) goals acute and chronic water quality criteria will apply. EPA used its 1999 Update of
Ambient Water Quality Criteria for Ammonia to evaluate protection of aquatic life. An evaluation of downstream state water quality
standards, namely the Iowa Department of Natural Resources (IDNR) Water Quality Standards, Chapter 61, of the Iowa
Administrative Code, was also conducted to ensure discharges from the Facility would not cause an exceedance of those state criteria.
Early Life Stages present criteria apply March through September, and Early Life Stages absent criteria apply October through
Februaiy. Because the effluent flow is greater than the stream flow during the critical time, rapid and complete mix is assumed. All
stream flow at the point of discharge will be considered for dilution. Water quality criteria is based on pH and temperature values of
the receiving stream flow. -1 -
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Outfall 003: Drinking Water Treatment Facility - Backwash Wastewater
In order to protect downstream users, EPA used IDNR's Total Residual Chlorine (TRC) criteria to determine the need for Water
Quality-based Effluent Limits (WQBEL) for TRC. The TRC criteria are 19 |ig/L acute and 11 |ig/L chronic. Raw well water is
currently being used to backflush the dual media filters. If the facility uses potable finished water containing chlorine to backflush the
filters, monitoring for TRC with limitations will be required. The PWTF is required to maintain a chlorine residual of 1.3 mg/L in the
finished water.
Ammonia
Outfall 001: Mechanical Treatment Facility - Treated Effluent
There is reasonable potential for the facility to exceed water quality criteria for ammonia. Below are the assumptions and equations
used in the calculation of reasonable potential. It was assumed there was no in-stream ammonia decay and the facility average daily
discharge flows for each season was used in the calculations. Current background ammonia concentrations were obtained from the
Iowa Department of Natural Resources, Water Quality Monitoring and Assessment Section, on October 31, 2022.
The following equation was used in the calculation of the Waste Load Allocations (WLAs) for this facility:
WLA = WOS * (stream flow + discharge flow) - (background concentration * stream flow)
discharge flow
The calculated permit limits are based on the chronic waste load allocation for the periods March through May and June through
September and the acute waste load allocation for the period October through February.
Since pH and temperature are the "drivers" that determine acute and chronic water quality criteria, EPA has decided to split the Early
Life Stage present period into a spring period (March - May) and a summer period (June - September).
Proposed Calculated Permit Limits
Spring Season (Early Life Stages Present) March through May
Daily Maximum Limit - 4.07 mg/L
Monthly Average Limit -1.71 mg/L
Summer Season (Early Life Stages Present) - June through September
Daily Maximum Limit - 3.25 mg/L
Monthly Average Limit -1.62 mg/L
Winter Season (Early Life Stages Absent) - October through February
Daily Maximum Limit - 6.09 mg/L
Monthly Average Limit - 3.04 mg/L
Existing Permit Limits
Spring Season (Early Life Stages Present) March through May
Daily Maximum Limit - 5.85 mg/L
Monthly Average Limit - 2.71 mg/L
Summer Season (Early Life Stages Present) - June through September
Daily Maximum Limit -4.13 mg/L
Monthly Average Limit -1.80 mg/L
Winter Season (Early Life Stages Absent) - October through February
Daily Maximum Limit - 5.92 mg/L
Monthly Average Limit - 2.26 mg/L
See Ammonia Waste load Allocation Setup Sheet below for further detail.
See Wasteload Allocation Development Sheets below for further detail.
See Reasonable Potential Development Sheet below for further detail.
Methods based on Technical Support Document for Water Quality-based Toxics Control (EPA/505/2-90-001 PB91 127415, March
1991).
-2-
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AMMONIA WASTELOAD ALLOCATION SETUP SHEET
Prepared by Gerald H. Memming on November 23.2022
Facility Name
Sac and Fox Meskwaki Nation - Outfall 001
Permit Number
LA.0073750
Pollutant
Ammonia
Seasons in Permit Limits
Spring
Summer
Winter
Months in Season
Mar-May
June-Sept
Oct-Febr
Stream Flovr (cfs) Acute - Onion Creek
0.1304
0.0230
0.0186
Used area ratio between USGS gage stations and EPA s DFLOW Model
Stream Flow (cfs) Chronic - Onion Creek
0.3949
0.0895
0.0527
Used area ratio between USGS gage
stations and EPA's DFLOW Model
Effluent Discharge (MGD)
0.28985
0.2342
0.1839
Used Average Monthly Discharge Flow of Facility
Background concentration (mg/L) Acute
0.06
0.02
0.034
Data provided by IDNR. Iowa WLA Procedure. November 11.
2020
Background concentration (mgL) Chronic
0.06
0.02
0.034
Data provided by IDNR. Iowa WLA Procedure. November 11,
2020
Stream pH
8.2
8.225
8.2
Data provided by IDNR. Iowa WLA Procedure. November 11.
2020
Stream Temperature :C
8.6
21.85
4.68
Data provided by IDNR. Iowa WLA Procedure. November 11.
2020
% mixing (0-1) Acute
1
1
1
Used complete mixing zone value
% mixing (0-1) Chronic
1
1
1
Used complete mixing zone value
Ammonia WQS Acute
5.72
5.47
5.72
Table 3a. IDNR Chapter 61. Water Quality Standards
Ammonia WQS Chronic
0.92
1.078
2.91
Tables 3b and3c. IDNR Chapter 61. Water Quality Standards
Is this a Controlled Discharge Lagoon? (y/n]
n
n
n
Salmonic Present? (y/n)
n
n
n
Early Life Stages Present? (y/n)
y
y
n
Ammonia Wasteload Allocation Development Sheets
1. Spring Season (March - May)
Facility Name- Sac and Fox Meskwaki Nation - Outfall 001
Permit Number- IA0073750 Pollutant:
11/18/2022
Ammonia
Multipliers
3.11
MDL
1 31
AML
0.32
LTAa
078
LTAc
monitoring samples
CV
Design flow MGD=
rt Used
12
0.6
0.42
12
WLA = WQSVstream flow + discharge flow) - (background cc
discharge flow
LTAa = WLA acute " LTAa multiplier
LTAc = WLA chronic * LTAc multiplier
AML mg/L = the smaller LTA (LTAa or LTAc) * AML multiplier
DML mg/L = the smaller LTA (LTAa or LTAc) * DML multiplier
AML lbs/day = AML mg/L ' discharge flow * 8 34
DML lbs/day = DML mg/L * discharge flow * 8 34
Acute WLA Chronic WLA LTAa LTAc
Concentration limits
Mass limits
AML mg/L
MDL mg/L
AML #/d
DML m
Spring (March-May)
7.363
1.678
2 364
1 308
1.710
4.073
5 989
14 266
Input data for Limits calculator
Seasons in Permit Limits Spring
Months in Season March-May
Stream Flow (cfs) Acute 0 1304
Stream Flow (cfs) Chronic 0.3949
Effluent Discharge (MGD) 0 28985
Background concentration (mg/L) Acute 0.06
Background concentration (mg/L) Chronic 0 06
Stream pH 8 2
Stream Temperature °C 8 6
% mixing (0-1) Acute 1
% mixing (0-1) Chronic 1
WQS Acute* 5 72
was Chronic* 0 92
Salmonid Present? (yM) n
Early Life Stages Present? (y/n) y
'* Calculated Ammonia Water Quality Criteria are based on EPA's 1999 Ammonia Criteria Update
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2. Summer Season 0une - September)
Facility Name- Sac and Fox Meskwaki Nation - Outfall 001
Permit Number- IAQ073750 Pollutant
11/18/2022
Ammonia
Multipliers
3.11
MDL
1 55
AML
0 32
LTAa
078
LTAc
monitoring samples
12
CV
0.6
Design flow MGD-
0.42
n Used
4
WLA = WQS'istream flow + discharge flow) - (background cc
discharge flow
LTAa = Wl-A acute * LTAa multiplier
LTAc = WLA chronic * LTAc multiplier
AML mg^L = the smaller LTA (LTAa or LTAc) * AML multiplier
DML mg/L = the smaller LTA (LTAa or LTAc) * DML multiplier
AML lbs/day = AML mg/L' discharge flow * 8 34
DML lbs/day = DML mg/L' discharge flow' 8 34
Acute WLA Chronic WLA LTAa LTAc
Concentration limits
Mass limits
AML mg/L
MDL mg/L
AMLWd
DML #/d
Summef (June-Sept)
5815
1 339
1 887
1 045
1 622
3 254
5.681
11 397
Input data for Limits calculator
Seasons In Permit Limits Summer
Months in Season June-Sept
Stream Flow (cfs) Acute 0 0230
Stream Flow (cfs) Chronic 0 0895
Effluent Discharge (MGD) 0 23420
Background concentration (mg/L) Acute 0 02
Background concentration (mg/L) Chronic 0 02
Stream pH 8 2
Stream Temperature °C 21 85
% mixing (0-1) Acute 1
% mixing (0-1) Chronic 1
WQS Acute* 5.47
WQS Chronic' 1.078
Salmonid Present? (y/n)
Early Life Stages Present? (y/n)
' Calculated Ammonia Water Quality Criteria are based on EPA's 1999 Ammonia Criteria Update
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3. Winter Season (October - February)
Facility Name- Sac and Fox Meskwaki Nation - Outfall 001
Permit Number- IA0073750 Pollutant
11/18/2022
Ammonia
Multipliers
3 11
MDL
1 55
AML
0 32
LTAa
0.78
LTAc
monitoring samples
12
CV
0.6
Design Row MGD=
042
n Used
4
WLA- WQS'(stream flow + discharge flow! • (background <
discharge flow
LTAa = WLA acute * LTAa multiplier
LTAc = WLA chronic * LTAc multiplier
AML mg/L - the smaller LTA (LTAa or LTAc) * AML multiplier
~ML mg/L = the smaller LTA (LTAa or LTAc) * DML multiplier
AML lbs/day = AML mg/L * discharge flow * 8 34
DML lbs/day = DML mg/L * discharge flow * 8.34
Acute WLA Chronic WLA LTAa LTAc
Concentration limits
Mass limits
AML mg/L
MDL mg/L
AML #/d
dml m
Winter (Oct-F«br)
6 091
3442
1 956
2 686
3 036
6091
10 635
21 336
Input data for Limits calculator
Seasons In Permit Limits Winter
Months in Season Oct-Febr
Stream Flow (cfs) Acute 0 0186
Stream Flow (cfs) Chronic 0 0527
Effluent Discharge (MGD) 0 1839
Background concentration (mg/L) Acute 0 034
Background concentration (mg/L) Chronic 0 034
Stream pH 8 2
Stream Temperature °C 4 68
% mixing (0-1) Acute 1
% mixing (0-1) Chronic 1
WQS Acute- 5 72
WQS Chronic* 2 91
Salmonid Present? (y/n)
Early Life Stages Present? (y/n)
'* Calculated Ammonia Water Quality Criteria are based on EPA's 1999 Ammonia Criteria Update.
Ammonia Reasonable Potential Development Sheet
Reasonable Potential Development for Water Quality Based Effluent Limitations
Facility Name-
Sac and Fox Meskwaki Nation WWTF - Outfall 001
Date:
11/28/2022
NPDES Permit Number-
IA0073750
Outfall 001
Undesignated Tributary to Iowa River (Onion Creek)
Pollutant: Ammonia
Spring
Summer
Winter
Acute
Chronic
Acute
Chronic
Acute
Chronic
Stream Flow (cfs)
Effluent Discharge (MGD)
0.1304
0.28985
0.3949
0.28985
0.0230
0.2342
0.0895
0.2342
0.0186
0.1839
0.0527
0.1839
Reasonable Potential Multiplying Factors (@ 99% & 99%)
Number of
Observations
CV
Background concentration (mg/L)
0.06
0.060
0.020
0.020
0.034
0.034
0.2
0.4
0.6
0.8
1
Water Quality Standard
5.72
0.92
5.47
1.078
5.72
2.91
1
2.5
6
13.2
26.5
48.3
% mixing (0-1)
1.0
1.0
1.0
1.0
1.0
1.0
2
2
4
7.4
12.7
20.2
CV (0.6 is recommended)
0.6
0.6
0.6
0.6
0.6
0.6
3
1.9
3.3
5.6
8.9
13.4
Number of monitored data
5
5
9
9
8
8
4
1.7
2.9
4.7
7.2
10.3
Maximum Observed value
1.83
1.83
1.50
1.50
6.90
6.90
5
1.7
2.7
4.2
6.2
8.6
Multiplier from table
4.2
4.2
3.2
3.2
3.3
3.3
6
1.6
2.5
3.8
5.5
7.5
Predicted max effluent concentration
7.686
7686
4.800
4.800
22.770
22.770
7
1.6
2.4
3.6
5
6.7
Down Stream Concentration
5.970
4.119
4.515
3.855
21.377
19.222
8
1.5
2.3
3.3
4.6
6.1
Reasonable Potential?
yes
yes
no
yes
yes
yes
9
1.5
2.2
3.2
4.3
5.7
10
1.4
2.2
3
4.1
5.3
11
1.4
2.1
2.9
3.9
5
12
1.4
2
2.8
3.7
4.7
13
1.4
2
2.7
3.6
4.5
Effluent concentration = Max Observed * Multiplier
14
1.4
2
2.6
3.4
4.3
15
1.4
1.9
2.5
3.3
4.1
Down Stream Concentration =
16
1.4
1.9
2.5
3.2
4
(Effluent Discharae * Effluent concentration) + (Background concentration * Stream Flow)
17
1.4
1.9
2.5
3.1
3.8
(Effluent Discharge + Stream Flow)
18
1.4
1.9
2.4
3
3.7
19
1.4
1.8
2.4
3
3.6
NOTE: Data entree from April 2018 through June 2022
20
1.3
1.8
2.3
2.9
3.5
>20
Use HighestValue
-5-
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Total Residual Chlorine (TRC)
Outfall 003: Public Water Treatment Facility - Backwash Wastewater Effluent
See Total Residual Chlorine (TRC) Wasteload Allocation Setup Sheet below for further detail.
See Wasteload Allocation Development Sheet below for further detail.
Methods based on Technical Support Document for Water Quality-based Toxics Control (EPA/505/2-90-001 PB91 127415,
March 1991).
TOTAL RESIDUAL CHLORINE WLA SETUP SHEET
Prepared by Memtraiif cnXroofcer Zis 1121
Fz:ilitv
i2z z.r.6 Ten I
Irik" -ak: I'atior. - C strati C
u *
Permit
:acc~5~5C
?s'\hzznt
Total Chlcrins l.TFvC'
SeatQE.1 in Permit Liruif:
Pfi;=nt
Atifctt?
Month; jti
Mar-:~pt
Cct-Febr
Mrs am Fie-- - I"-a
55. :s
i> 5-
Unz arsa iziic s*r..V'S*n fagrs sratscm aid E?A 5 DFLO'.V Icd* i
^i'42U"51 Fie"' Ufz' Chi'Cili; - FLj'--ci"
6-.56
¦i2 51
Usid aria ia:ic U:G:i ?a?i stations and EPA ; DFLO'-V Modit
E::r.iiiit Dlsikarf- :)-IGD.
C.1555
C-L.555
Ussd A'-'srafs Mcntb-y Diiiharf- flc— c-f Fa_ui:y
Backn-c^rtd tcncs-ntrancn [tv.z L. Ar:;i
C
Difaul: Ea:k=rrr^nd
Background iznc^r.traticu: nil L . Cnrcni;
c
Default Barkirs^ni
5'rimi rH
8.21
S.2
Background "ibsi prc-'idid by ID>7R. lo-va. *.VLA Prcisd-jirs. 2C2C
iWizsii :C
16-1"
-iS
Barkit'C'snd ~'ab~ yrevji-d by ID1CF.. ?rcc~chi'i. 2C2C
:rviL'iinz 'C-l;
C.025
C.E25
ID".-TF. rnbiin? rcn* vahii. Ic"-a v.lA Pre ir-d^ri. Nov. 2C'22
:: rnt-ntr:? Clii'Cf.:;
C
C.25
ID"-?. n;i>;inf r;r.i vak>~. Io-"a vTLA Pro:* isr-. 2-cv. 2C2C
Xcri itrar-cnia WQI- A:u:i
c.c;s
c.c;s
IDIvF. Qualify arars intrTia
sjiin'-cnii Chrcni:
c-c;:
" c*'
ID Is?.IVarii Quality rhtoni:
Zi this, i L crtEicUri Disdiarp Liiccr." ;y n
tt
n
Prii-sf.!:? fyn'
V
n
Early Lif= ikapi Pi-iisrj" :.y r.'
y
n
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TRC Wasteload Allocation Development Sheets
1. Early Life Stages Present (March - September)
Facility Name-
Sac and Fox Meskwaki - Outfall 003
11/21/2022
Permit Number-
IA0073750
Pollutant:
Total Residual Chlorine (TRC)
Multipliers
WLA = WQS'fstream flow + discharoe flow) - fbackaround concentration * stream flow)
3.114
MDL
discharge flow
1.552
AML
LTAa = WLA acute * LTAa multiplier
0 321
LTAa
LTAc = WLA chronic * LTAc multiplier
0.527
LTAc
AML mg/L = the smaller LTA (LTAa or LTAc) * AML multiplier
monitoring samples
0
DML mg/L = the smarter LTA (LTAa or LTAc) * DML multiplier
CV
0,6
AML lbs/day = AML mg/L * discharge flow * 8.34
Design flow MGD=
28
DML lbs/day = DML mg/L ' discharge flow * 8.34
n Used
4
Acute WLA Chronic WLA LTAa LTAc
Concentration limits
Mass limits
AML mg/L
MDL mg/L
AML #/d
DML m
Present (March-Sept)
0.130
0 748
0.042
0.394
0.065
0.130
1.510
3.030
Input data for Limits calculator
Seasons in Permit Limits Present
Months in Season March-Sept
Stream Flow (cfs) Acute 56.19
Stream Flow (cfs) Chronic 64.56
Effluent Discharge (MGD) 0.1555
Background concentration (mg/L) Acute 0
Background concentration {mg/L) Chronto 0
Stream pH 8.21
Stream T emperature °C 16.17
% mixing (0-1) Acute 0.025
% mixing (0-1) Chronic 0.25
WQS Acute* 0.019
WQS Chronic* 0.011
Satmonid Present? (y/n) y
Early Life Stages Present? (y/n) y
2. Early Life Stages Absent (October - February)
Facility Name- Sac and Fox Meskwaki - Outfall 003
Permit Number- IA0073750 Pollutant:
11/21/2022
Total Residual Chlorine (TRC)
Multipliers
3.114
MDL
1.552
AML
0.321
LTAa
0.527
LTAc
monitoring samples
0
CV
0.6
Design flow MGD=
28
n Used
4
WLA = WQS*(stream flow + discharge flow) - (background concentration * stream flow)
discharge flow
LTAa = WLA acute * LTAa multiplier
LTAc = WLA chronic * LTAc multiplier
AML mg/L = the smaller LTA (LTAa or LTAc)" AML multiplier
DML mg/L = the smaller LTA (LTAa or LTAc) * DML multiplier
AML lbs/day = AML mg/L * discharge flow * 8.34
DML lbs/day = DML mg/L * discharge flow * 8.34
Acute WLA Chronic WLA LTAa LTAc
Concentration limits
Mass limits
AML mg/L
MDL mg/L
AML #/d
DML m
Absent (Oct-Sept)
0.097
0.494
0.031
0.260
0.048
0.097
1 128
2.263
Input data for Limits calculator
Seasons in Permit Limits Absent
Months in Season Oct-Sept
Stream Flow (cfs) Acute 39.54
Stream Flow (cfs) Chronic 42.31
Effluent Discharge (MGD) 0.1555
Background concentration (mg/L) Acute 0
Background concentration (mg/L) Chronic 0
Stream pH 8.20
Stream Temperature °C 4.68
% mixing (0-1) Acute 0.025
% mixing (0-1) Chronic 0.25
WQS Acute* 0.019
WQS Chronic* 0.011
Salmonid Present? (y/n) n
Early Life Stages Present? (y/n) n
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