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HomeMy WebLinkAboutNC0089907_Fact Sheet_20200514MUNICIPAL FACILITY FACT SHEET NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM PERMIT TO DISCHARGE TREATED WASTEWATER TO WATERS OF THE UNITED STATES Permit No.: NCO089907 1. Summary of Permit Changes Not applicable since this is a new permit. 2. Facility Information A. Name and Address of Permittee: B. Facility Address: C. Type of Facility: Last Updated: May 6, 2020 Eastern Band of Cherokee Indians P.O. Box 455 Cherokee, North Carolina 28719 Jacob Cornsilk Complex 314 Cornsilk Branch Road Robbinsville, North Carolina 28771 Municipal Wastewater Treatment Plant Publicly -Owned Treatment Works (POTW) Standard Industrial Classification Code: 4952 D. Location and Description of the discharge (as reported by applicant): Outfall Latitude Longitude Receiving Watershed Waterbod 001 35018'13.0" N 83°52'24.1" W Snowbird Creek Lower Little Tennessee HUC 06010204 E. Permitted Capacity: 0.03 MGD F. Description of Wastewater Treatment Facility: Outfall Operation Description Treatment Description 1 Sanitary Wastewater Treatment consists of influent equalization, followed by attached -growth aerobic biological treatment, ultraviolet (UV) disinfection, and effluent flow monitoring. Estimated population served is 140. G. Type of Wastewater Discharge: ❑ Process Wastewater ❑ Stormwater ® Domestic Wastewater ❑ Combined (describe) ❑ Other (describe) H. Characterization of Effluent No data are available since this is a new facility. This data will be collected within 24 months of issuance in accordance with Item 1.2 in Application Form 2A (EPA Form 3510-2A). 3. Water Ouality Standards & Receiving Waterbody Information A. Receiving Waterbody Classification and Information — The discharge goes into Snowbird Creek, which is within the Cheoah River subwatershed. Based on the Eastern Band of Cherokee Indians' (EBCI) Water Quality Standards (WQS), Cherokee waters within the Cheoah River subwatershed are designated for Ceremonial, Recreation, and Cold -Water Aquatic Habitat uses (3.2). Downstream, the State of North Carolina WQS are applicable as well. The section of Snowbird Creek within the State of North Carolina downstream of the discharge has designated uses of Class C (Secondary Recreation, Fishing, Aquatic Life, and Wildlife) and Tr (Trout Waters). By developing this permit to comply with the Tribe's promulgated criteria, this permit is protective of downstream State -designated uses. B. Specific Water Quality Criteria for Classified Water Usage The following are the most protective of criteria within the following applicable use classifications: a. Nutrients: Except as due to natural conditions, nutrients shall not be allowed in concentrations that render the waters unsuitable for the existing or designated uses due to objectionable algal densities, nuisance aquatic vegetation, diurnal fluctuations in dissolved oxygen, or pH indicative of excessive photosynthetic activity, detrimental changes to the composition of aquatic ecosystems or other indicators of use impairment caused by nutrients. b. Flow: Natural daily, seasonal, annual, and inter -annual fluctuations of flow shall be maintained to support the naturally balanced indigenous biological community including those species most sensitive to alterations in flow, including trout and all life stages of trout. c. pH: The normal pH of the water shall be 6.0 to 9.0 and shall not vary more than 1.0 unit. d. Bacteria: Escherichia coli shall not exceed a geometric mean of 126 per 100 mL nor shall more than ten percent of the samples examined during any month exceed 410 per 100 mL. e. Dissolved Oxygen: A minimum concentration of 6.5 mg/L as a daily average and 5 mg/L as an instantaneous minimum shall be maintained at all times. f. Temperature: Water temperature shall not be increased by more than 0.5 °C as a result of discharge and in no case be increased to exceed 20 °C (68 °F), the required temperature necessary to support trout habitat. g. Solids: Neither total dissolved solids nor total suspended solids shall be changed to the extent that the indigenous aquatic community is adversely affected. No settleable solids shall be added that may adversely alter the stream bottom. h. Ammonia: Ammonia criteria shall be in accordance with EPA recommendations as expressed on pages 40, 41, 42, 44, 45, 46, and 49 of Aquatic Life Ambient Water Quality for Ammonia — Freshwater 2013 (April 2013, EPA-822-R- 13 -00 1). Such information is hereby incorporated by reference. Where mussels in the order Unionoida are absent at a site, ammonia criteria may be calculated on a site -specific basis. Any such site -specific criteria shall be in accordance with the equations and tables expressed on pages 228, 229, 231, 235, 236, 239, and 240 in Appendix N of the document referenced above. i. Toxicants a. Narrative: 1. Aquatic Life Criteria: The concentration of toxic substances shall not result in chronic or acute toxicity or impairment of the uses of aquatic life and shall not exceed the chronic or acute criteria in Table 1, unless within a mixing zone or a site - specific criterion is developed consistent with the documented procedures. 2. Human Health Criteria: The concentration of toxic substances shall not exceed the level necessary to protect human health through exposure routes of fish tissue consumption, water consumption, or other routes identified as appropriate for the particular body of water, as presented in Table 2. "Water and Organisms" criteria assume the consumption of 2.4 liters of water and 22.0 grams of fish per day, while the "Organisms Only" criteria are based on the consumption of 22.0 grams of fish per day. b. Numerics: Eastern Band of Cherokee Indians Water Quality Standards: Administrative Rules Appendix A: Table 1 and Table 2 "Free-Froms": All surface waters, including those within the mixing zone, must be capable of supporting aquatic life and shall be free from: a. Substances that settle to form objectionable deposits or sediments, b. Floating debris, scum, oil, and other floating materials that form a nuisance or interfere with designated water uses, c. Material or practices that produce objectionable color, odor, taste, or turbidity, d. Substances which are acutely toxic or produce adverse physiological or behavioral responses in humans, animals, plants, fish and other aquatic life, e. Substances which produce undesirable aquatic life or result in the dominance of nuisance species, and f. Substances which cause fish flesh tainting. C. Critical Flows — Implementing ECBI water quality standards requires consideration of flow design criteria for effluent limitations. Due to minimal flow data in the receiving waterbody, conservative assumptions were made regarding critical flows, resulting in a 7Q10 flow consistent with the 7Q10 cited in the EBCI Environmental Information Document, August 20191. Snowbird Creek: 7Q 10 = 31 cubic feet per second (cfs) D. 303(d) Status — Snowbird Creek has not been assessed for water quality by the EBCI. Based on ' Environmental Information Document for a New Wastewater Treatment Plant, Jacob Comsilk Complex, Robbinsonville, North Carolina, Prepared for Eastern Band of Cherokee Indians by Civil & Environmental Consultants, Inc., CEC Project 191-994, August 2019. the State of North Carolina's 2018 Integrated Report, Snowbird Creek was assessed in 2014 and is meeting its designated aquatic life use. E. Total Maximum Daily Loads — A statewide mercury TMDL was finalized in 2012. 4. Effluent Limits and Permit Conditions A. Proposed Effluent Limitations for Outfall 001 DISCHARGE LIMITATIONS MONITORING REQUIREMENTS Daily Monthly Weekly Daily Sampling Measurement PARAMETERS Min AvgAvgMax Location FrequencySample Type Flow, MGD --- Report Report --- Effluent 2/Month Instantaneous Dissolved Oxygen (DO), 3.0 --- --- --- Effluent 2/Month Grab m /l Carbonaceous --- Report ___ --- Influent Biochemical Effluent Oxygen Demand --- 25.0 40.0 --- 2/Month Grab 5-Day (CBOD5), --- (6.26) (10.01) --- m /1 lbs/da Carbonaceous Biochemical Oxygen Demand 85%a Influent/ 2/Month Calculated 5-Day (CBOD5) Effluent Percent Removal, Total Suspended --- Report --- --- Influent Solids (TSS), --- 30.0 45.0 --- Effluent 2/Month Grab mg/l (lbs/day) --- 7.51(11.26)--- Total Suspended Solids (TSS) 85%a Influent/ 2/Month Calculated Percent Removal, Effluent pH, standard 6.0 --- --- 9.0 Effluent 2/Month Instantaneous units SU E. coli, #/100 mL --- 126b --- 4101 Effluent 2/Month Grab Temperature --- Report Report 1 Effluent 2/Month Grab Total Nitrogen (TN) as Nitrogen, --- Report Report --- Effluent Monthly Grab mg/1 DISCHARGE LIMITATIONS MONITORING REQUIREMENTS PARAMETERS Daily Monthly Weekly Daily Sampling I Measurement Sample Type Min Avg Avg Max Location Frequency Total Phosphorus, (TP) --- Report Report --- Effluent Monthly Grab as Phosphorous, mg/1 Ammonia 10.0 15.0 Nitrogen, (NH3- --- --- Effluent 2/Month Grab N), m /l (2.50) (3.75) a Each month, the average effluent CBOD5 and TSS concentrations shall not exceed 15% of the average of their respective influent concentration values (85% removal). b The geometric mean of the E. coli values collected during any monthly period shall not exceed 126 colonies per 100 ml of effluent sample and shall be reported as the monthly average value. No more than ten percent of the E. coli samples examined during any month shall exceed 410 colonies per 100 ml. B. Reasonable Potential (RP) Title 40 of the Federal Code of Regulations, 40 CFR 122.44(d) requires NPDES permit issuing authorities to develop procedures for determining whether a discharge causes, has the reasonable potential to cause, or contributes to an instream excursion above a narrative or numeric criterion. If such reasonable potential is determined to exist, the NPDES permit must contain pollutant effluent limits and/or effluent limits for whole effluent toxicity. The EPA's reasonable potential analysis is based on guidelines provided in the "U.S. EPA NPDES Permit Writer's Manual (2010)" and its references. No effluent data were available, and reasonable potential was simulated or calculated using assumed values, as discussed below. C. Basis for Conventional Pollutants Limits Pollutant of Basis Concern pH, SU The effluent limitation range for pH was based on minimum level of effluent quality requirements of 40 CFR § 133.102 for discharges of wastewater from POTWs. 5-Day Effluent CBOD5 limits in the permit include a monthly average concentration of 25.0 mg/l Carbonaceous and a weekly average concentration of 40.0 mg/l, which are based on secondary treatment Biochemical standards. Effluent CBOD5 loading limits of 6.26 lbs/day monthly average and 10.01 Oxygen Demand lbs/day weekly average are also included in this permit; they are based on the design flow (CBOD5), mg/1 as reported on the application. The CB0D5 limits are based on meeting the EBCI's DO standard of 6.5mg/L at the point of discharge and are protective of the State of North Carolina's downstream water quality standard of 6.0 mg/L in Snowbird Creek down to Lake Santeetlah, as modeled through QUAL2K. The percent removal limitation for C130135 is based on the minimum level of effluent quality requirements of 40 CFR § 133.102 for discharge of waters from POTWs. For calculation of the percent removal, influent CBOD5 monitoring has been added. Total Suspended The effluent limitations for TSS are based on minimum level of effluent quality Solids (TSS), mg/1 requirements of 40 CFR § 133.102 for discharges of wastewater from POTWs. The permit includes monthly average limits of 30 mg/1 and 7.51 lbs/day and weekly average limits of 45 mg/1 and 11.26 lbs/da , as well as an 85% removal limitation and influent monitoring. E. coli, #/100m1 The effluent limitations for Escherichia coli are based on meeting the EBCI's water quality standards for ceremonial and recreational uses. The permit includes a monthly limit expressed as a geometric mean of 126 #/100 mL and a daily maximum limit that no more than ten percent of the samples examined during any month shall exceed of 410 #/100 ml. D. Basis for Nonconventional Pollutants Limits Pollutant of Basis Concern Ammonia, mg/l The permit includes monthly average ammonia limits of 10.0 mg/1 and 2.50 lbs/day and weekly average ammonia limits of 15.0 mg/1 and 3.75 lbs/day. Assuming rapid and instantaneous mixing at the point of discharge, model runs using QUAL2K show that the limits are protective of the EBCI's dissolved oxygen criteria at critical conditions. The basis for the ammonia limit was not water -quality based given that the instream waste concentration is 0.15% (see discussion below). Instead, the monthly and weekly average limits were selected based on BPJ and meeting the DO criteria. The potential for any near - field effects will be revisited. Dissolved Oxygen, The permit includes a daily minimum dissolved oxygen limit of 3.0 mg/l. Assuming rapid DO, mg/l and instantaneous mixing at the point of discharge, model runs using QUAL2K show that the limits are protective of EBCI's dissolved oxygen criteria for its cold -water aquatic habitat use. This limit is also protective of North Carolina's water quality standard for dissolved oxygen based on model results of downstream waters. The basis for the DO limit was not water -quality based given that the instream waste concentration is 0.15% (see discussion below). Instead, the daily minimum limit was selected based on BPJ. The potential for any near -field effects will be revisited. Total Nitrogen, Monitoring for Total Nitrogen is being required so that sufficient information will be mg/1 available from this point source should it be necessary at some later time to impose limits on this discharge. Total Phosphorus, Monitoring for Total Phosphorus is being required so that sufficient information will be mg/1 available from this point source should it be necessary at some later time to impose limits on this discharge. E. Calculations for Water Quality -Based Effluent Limits (WQBELs) a. Instream Waste Concentration (IWC) IWC (%) = Design Flow (gpd) X 100% Design Flow (gpd)+7Q10(gpd) IWC (%) = 30,000 gpd X 100% 30,000 gpd + 20,035,823.38 gpd IWC (%) = 0.15% in the Unnamed Tributary to Snowbird Creek b. Dissolved Oxygen (DO) i. Minimum DO Analysis The EBCI's DO criteria for its cold -water aquatic habitat use is a minimum concentration of 6.5 mg/L as a daily average and 5 mg/L as an instantaneous minimum. Given the small discharge flow relative to the receiving water, rapid and instantaneous mixing of the effluent is assumed at the point of discharge. Best professional judgement was used to select a daily minimum DO limit of 3.0 mg/L. The analysis below was done to show how a DO limit of 3.0 mg/L has negligible impacts to the receiving water. Rearranging a mass balance equation, CSQS + CdQd = GQ, results in the equation: C,- _ [(C,)(Q,) + (Cd)(Qd)] (Qr) Where: Cr = Receiving water concentration CS = Upstream receiving water concentration Q, = Upstream receiving water flow Cd = Effluent concentration Qd = Effluent flow Qr = Downstream receiving water flow Using the DO criteria for C, and 7Q10 flow for QS results in the equation: C,. _ [(6.5 mg/L)(20.04 MGD) + (3 mg/L)(0.03 MGD)] (20.04 + 0.03 MGD) Cr = 6.495 mg/L Selection of a minimum DO limit of 3.0 mg/L for the discharge results in a DO concentration of 6.495 mg/L in the receiving water. The difference between the resulting receiving water concentration compared to EBCI's DO criteria of 6.5 mg/L is immeasurable. These calculations account for multiple conservative assumptions, including the use of a 7Q10 flow for the receiving water and the facility's design flow. Additionally, the facility is predicted to routinely achieve higher DO concentrations in the effluent. Modeling using QUAL2K was run to meet a minimum target DO concentration of 6.5 mg/L in the receiving water. The model was used to analyze the effect of the facility's effluent on the receiving waterbody and determine CBOD5, ammonia, and DO limits that are protective of these criteria. See Appendix 1 for a description of the model. c. Ammonia i. Ammonia Toxicity Analysis The EBCI's WQS for ammonia references EPA's Aquatic Life Ambient Water Quality Criteria for Ammonia — Freshwater 2013 (EPA-822-R- 13-00 1). The below analyses were done to determine whether there is a reasonable potential for ammonia toxicity upon discharge. Criterion Maximum Concentration (CMC) - Oncorhynchus spp. Present CMC = MIN (24.10,(0.7249 x 23.12 (100.036x(20—T)))) Where: T = Temperature CMC = acute criterion magnitude for total ammonia Using average measured instream pH and temperature values of 7.1 SU and 18 °C correlates to an instream CMC of 18 mg/L, according to Table 5a of EPA's ammonia criteria document. _ [CMC x(Design Flow+7Q10)] — (7Q10 xCg) CE Design Flow _ [18 mg/L x(0.03+20.04 MGD)] — (20.04 x0) CE 0.03 Where: CB = Upstream ammonia concentration = 0 mg/L CE = Allowable ammonia effluent concentration, mg/L CE = 12,042 mg/L Criterion Continuous Concentration (CCC) 0.0278 1.1994 0 028 x(20—MAX(T,7)) CCC = 0.8876 x 1+10(7•688 - pH) + 1+10(pH - 7.688) x (2.126 x 10 ) CCC = Instream criterion continuous concentration for total ammonia Using average measured instream pH and temperature values of 7.1 SU and 18 °C correlates to an instream CCC of 2.1 mg/L, according to Table 6 of EPA's ammonia criteria document. _ [CCC x(Design Flow+7Q10)] — (7Q10 xCg) CE Design Flow CE _ [2.1 x (0.03 + 20.04 MGD)] — (20.04 x 0) 0.03 Where: CB = Upstream ammonia concentration = 0 mg/L CE = 1405 mg/L The allowable acute and chronic ammonia effluent concentrations are 12,042 mg/L and 1405 mg/L, given the small discharge flow relative to the receiving water. As such, the ammonia limits in the permit were not based on the allowable water -quality based ammonia effluent concentrations. Best professional judgement was used to select more reasonable ammonia limits of 10 mg/L (monthly average) and 15 mg/L (weekly average) that would result in compliance with a minimum, simulated instream DO concentration. The selected ammonia permit limits should not result in ammonia toxicity when compared to the allowable acute and chronic values calculated above. F. Applicable Technology -Based Effluent Limits (TBELs) Technology -based effluent limitations aim to prevent pollution by requiring a minimum level of effluent quality that is attainable using demonstrated technologies for reducing discharges of pollutants or pollution into the waters of the United States. Secondary Treatment Standards Parameter Secondary Treatment Standard CBOD5 25 mg/L Monthly Average 40 mg/L eekly Average TSS 30 mg/L Monthly Average 45 mg/L Weekly Average Removal 85% CBOD5 and TSS pH Maintained within the limits of 6.0-9.0 standard units G. Comparison & Summary of Water Quality -Based vs. Technology -Based Effluent Limits For each parameter, applicable technology -based limits (TBELs) were compared to the applicable water -quality based limits (WQBELs), and the most stringent limits were selected for the permit. The selected limits, indicated by bold text, were compared to the limits in the current permit, and all are at least as stringent as the current permit limits. Parameter Proposed Permit Limits WQBELs TBELs Daily Monthly Weekly Daily Daily Monthly Weekly Daily Min Avg Avg Max Min Avg Avg Max Flow, MGD --- Report Report --- --- --- --- --- Dissolved 3.0 --- --- Oxygen, m /l C130135, m /l 25.0 40.0 -- --- 25 37.5 --- lb/d (6.26) (10.01) CBOD5 % __ 85% Removal TSS, mg/l 30.0 45.0 lb/d 7.51 11,26 TSS % Removal --- 85% pH, S.U. 6.0 9.0 Ei.O --- 9.0 E. coli, #/100 --- 126 --- 410 --- ml Temperature --- Report Report --- --- TN, mg/1 --- Report Report --- --- TP, mg/1 --- Report Report --- --- Total Ammonia as 10.0 15.0 Nitrogen, (2.50) (3.75) mg/1 lb/d 5. 401 Certification The Clean Water Act (CWA) §401 statute and regulations stipulate that no federal permit or license can be issued that may result in a discharge to waters of the United States unless the state or authorized tribe certifies that the discharge is consistent with water quality standards and other water quality goals, or waives its certification authority. The CWA §401 regulations direct certifying agencies to conclude that the permitted activity will be consistent with effluent limitations for conventional and non -conventional pollutants, water quality standards, new source performance standards, and toxic pollutant limitations, and any other appropriate state and/or tribal requirements. A second component of the scope of the CWA §401 review is determining whether an activity requiring certification in one state or tribe (i.e., in the location where the discharge originates) may potentially impact the water quality of a neighboring state or tribe. In those instances, the EPA is directed to notify the state or tribe whose water quality may be affected, and other review processes may be triggered. The Eastern Band of Cherokee Indians has promulgated water quality standards. The permit was developed to be consistent with the EBCI's Water Quality Standards. It is protective of designated uses of tribal waters and with the other applicable provisions of the CWA (i.e., §§ 301, 302, 303, 306, and 307). The Tribe has been granted §401 certification authority, and this authority covers the issuance of this Permit. In addition, North Carolina has promulgated Water Quality Standards, and the permit is protective of the designated uses of North Carolina's waters. North Carolina has been granted §401 certification authority, and this authority covers the issuance of this Permit. 6. Services Consultation In accordance with 40 CFR § 122.49(c) the EPA is required to ensure, in consultation with the U.S. Fish and Wildlife Service (Service), that "any action authorized by the EPA is not likely to jeopardize the continued existence of any endangered or threatened species or adversely affect its critical habitat." In a letter dated February 19, 2020, the Service concurred with the EPA's determination that the project, as proposed, will not adversely affect federally listed species. According to a review of their records and of the information provided, no federally listed species or their habitat occur in Snowbird Creek. 7. National Environmental Policy Act (NEPA) This facility is not considered a "new source" according to the definitions at 40 CFR § 122.2 and therefore does not require an environmental assessment, environmental impact statement, or other information specified under 40 CFR § 124.9(b)(6). 8. National Historic Preservation Act Section 106 of the National Historic Preservation Act requires federal agencies to consider the effect of their undertakings on historic properties that are either listed on, or eligible for listing on, the National Register of Historic Places. As described in the EBCI Environmental Information Document, August 2019, EBCI consulted the Tribal Historic Preservation Office (THPO) to evaluate the potential for any historic and archeological preservation issues. THPO considers the probability for finding significant archaeological resources at the site of the Cornsilk Complex to be low and requested that EBCI monitor for artifacts during the initial phase of demolition and grading. 9. Public Participation The public notice for this draft permit will be published in The Cherokee One Feather with the permit documents available on the EPA Region 4 website. The public comment period will be open for 30 days after publication of the public notice. A response to comment document will be drafted and included with the final permit should any significant comments be received. DATE: May 6, 2020 AMENDMENT TO THE FACT SHEET AT TIME OF ISSUANCE PERMIT NO: NC0089907 NAME OF APPLICANT: Jacob Cornsilk Complex A. 401 Certification The Clean Water Act (CWA) §401 statute and regulations stipulate that no federal permit or license can be issued that may result in a discharge to waters of the United States unless the state or authorized tribe certifies that the discharge is consistent with water quality standards and other water quality goals, or waives its certification authority. The CWA §401 regulations direct certifying agencies to conclude that the permitted activity will be consistent with effluent limitations for conventional and non -conventional pollutants, water quality standards, new source performance standards, and toxic pollutant limitations, and any other appropriate state and/or tribal requirements. A second component of the scope of the CWA §401 review is determining whether an activity requiring certification in one state or tribe (i.e., in the location where the discharge originates) may potentially impact the water quality of a neighboring state or tribe. In those instances, the EPA is directed to notify the state or tribe whose water quality may be affected, and other review processes may be triggered. The Eastern Band of Cherokee Indians has promulgated water quality standards. The permit was developed to be consistent with the EBCI's Water Quality Standards. It is protective of designated uses of tribal waters and with the other applicable provisions of the CWA (i.e., §§ 301, 302, 303, 306, and 307). The Tribe has been granted §401 certification authority, and this authority covers the issuance of this Permit. In addition, North Carolina has promulgated Water Quality Standards, and the permit is protective of the designated uses of North Carolina's waters. As a courtesy to the downstream state, the draft permit and fact sheet were sent to North Carolina, with an opportunity to comment. B. Public Participation In accordance with 40 CFR § 124.10(d)(1), the Public Notice announcing the proposed issuance of the EPA Region 4's Individual NPDES Permit for Jacob Cornsilk Complex, No. NC0089907, was published on the EPA Region 4's website on March 18, 2020, along with the draft permit documents. The comment period was open for 30 days until April 18, 2020, and the EPA Region 4 received no comments during this time. Appendix 1— Description of QUAL2K2 QUAL2K (or Q2K) is a river and stream water quality model that is intended to represent a modernized version of the QUAL2E (or Q2E) model (Brown and Barnwell 1987). Q2K is similar to Q2E in the following respects: • One dimensional. The channel is well -mixed vertically and laterally. • Branching. The system can consist of a mainstem river with branched tributaries. • Steady state hydraulics. Non -uniform, steady flow is simulated. • Diel heat budget. The heat budget and temperature are simulated as a function of meteorology on a diel time scale. • Diel water -quality kinetics. All water quality variables are simulated on a diel time scale. • Heat and mass inputs. Point and non -point loads and withdrawals are simulated. The QUAL2K framework includes the following new elements: • Software Environment and Interface. Q2K is implemented within the Microsoft Windows environment. Numerical computations are programmed in Fortran 90. Excel is used as the graphical user interface. All interface operations are programmed in the Microsoft Office macro language: Visual Basic for Applications (VBA). • Model segmentation. Q2E segments the system into river reaches comprised of equally spaced elements. Q2K also divides the system into reaches and elements. However, in contrast to Q2E, the element size for Q2K can vary from reach to reach. In addition, multiple loadings and withdrawals can be input to any element. • Carbonaceous BOD speciation. Q2K uses two forms of carbonaceous BOD to represent organic carbon. These forms are a slowly oxidizing form (slow CBOD) and a rapidly oxidizing form (fast CBOD). • Anoxia. Q2K accommodates anoxia by reducing oxidation reactions to zero at low oxygen levels. In addition, denitrification is modeled as a first -order reaction that becomes pronounced at low oxygen concentrations. • Sediment -water interactions. Sediment -water fluxes of dissolved oxygen and nutrients can be simulated internally rather than being prescribed. That is, oxygen (SOD) and nutrient fluxes are simulated as a function of settling particulate organic matter, reactions within the sediments, and the concentrations of soluble forms in the overlying waters. • Bottom algae. The model explicitly simulates attached bottom algae. These algae have variable stoichiometry. • Light extinction. Light extinction is calculated as a function of algae, detritus and inorganic solids. • pH. Both alkalinity and total inorganic carbon are simulated. The river's pH is then computed based on these two quantities. • Pathogens. A generic pathogen is simulated. Pathogen removal is determined as a function of temperature, light, and settling. • Reach specific kinetic parameters. Q2K allows you to specify many of the kinetic parameters on a reach - specific basis. • Weirs and waterfalls. The hydraulics of weirs as well as the effect of weirs and waterfalls on gas transfer are explicitly included. 2 Chapra, S.C., Pelletier, G.J. and Tao, H. 2008. QUAL2K: A Modeling Framework for Simulating River and Stream Water Quality, Version 2.11: Documentation and Users Manual. Civil and Environmental Engineering Dept., Tufts University, Medford, MA. Appendix 2 — Summary of Instream Monitoring EBCI conducted a baseline sampling study in Snowbird Creek prior to submitting an NPDES permit application since there were no available water quality data. The sampling study consisted of samples collected from four locations in the creek - one site upstream and three downstream of the proposed facility. Sampling was conducted every other week from May 22, 2019 to August 14, 2019 for the following parameters: • Dissolved Oxygen • Temperature • pH • Conductivity • Total Kjeldahl Nitrogen • Total Nitrogen • Nitrate • Nitrite • Ammonia -Nitrogen • Total Phosphorus • Phosphate • 5-day Carbonaceous Biochemical Demand • Total Suspended Solids • Turbidity Water quality samples were collected by personnel from EBCI Natural Resources and measured or analyzed using approved methods. The sampling results are presented in Tables 1-3 of the EBCI Environmental Information Document, August 2019. Based on the monitoring results, paired with historical flow data, the ECBI document concludes that "the effluent from a well operated and properly designed WWTP should have virtually no measurable effect on the water quality in Snowbird Creek, even at low -flow conditions."