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 - ------- 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- ------- 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 3- ------- 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 ------- 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- ------- 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 ------- 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 ------- |