Fiddler s Lake Treatment System Plan

Transcription

1 Fiddler s Lake Treatment System Plan Final Report September 15, 2014 Fiddler s Lake Treatment System Plan Final Report Public Works and Engineering, City of Yellowknife Gary Strong - Project Manager Submitted by Dillon Consulting Limited R:\PROJECTS\DRAFT\2011\ Fiddlers Lagoon\Reports\Fiddler s Lake Treatment System Plan\Fiddler s Lake Treatment System Plan Final Report.pdf

2 September 15, 2014 Public Works & Engineering City of Yellowknife P.O. Box 580 Yellowknife, NT X1A 2N4 Attention: Cc: Re: Wendy Alexander Manager, Engineering Mike Auge Municipal Works Engineer Fiddler s Lake Treatment System Plan Final Report Dear Ms. Alexander: Please find enclosed one (1) electronic copy of the Final Report entitled Fiddler s Lake Treatment System Plan for your review and comments. We hope this meets your requirements at this time. Should you have any questions or concerns regarding this submission, please feel free to contact me, by at gstrong@dillon.ca or by telephone at ext Yours sincerely, DILLON CONSULTING LIMITED Gary Strong, P. Eng. Project Manager R:\PROJECTS\DRAFT\2011\ Fiddlers Lagoon\Reports\Fiddler s Lake Treatment System Plan\Fiddler s Lake Treatment System Plan Final Report.pdf

3 TABLE OF CONTENTS Page No. 1 INTRODUCTION Objective of Study BACKGROUND INFORMATION Fiddler s Lake Wastewater Lagoon System CCME Strategy for Managing Municipal Wastewater Effluent in the North PROJECTION CRITERIA Population Growth Sewage Generation Rates Current Effluent Limits FIDDLER S LAKE TREATMENT SYSTEM BIOLOGICAL MODELING Wastewater Flow and Load Historical Performance of Treatment System Holding Capacity Projected Holding Capacity for Project Years 5, 10 and MODEL CONSTRUCTION AND CALIBRATION Calibration Dataset Model Configuration Calibration Results Estimating Future Treatment Conditions NUTRIENT REDUCTION IN COLD CLIMATES Current and Future outlook for Fiddler s Lagoon Phosphorus Reduction Ammonia Reduction Increase in Lagoon Retention Time CONCLUSIONS REFERENCES... 29

4 TABLE OF CONTENTS (Cont d) Page No. LIST OF FIGURES Figure 1: Overview of Fiddler's Lake Treatment System... 4 Figure 2: Historical and Future Population Growth Trends at 1.2% per Annum... 6 Figure 3: Fiddler s Lake Treatment System Lagoon Cell Biological Model Configuration LIST OF TABLES Table 1: Predicted Population for Project Design Horizons: Years 5, Year 10 and Year Table 2: Predicted Wastewater Production for Design Horizon Year 5, 10 and 20 based on L/c/d Resdential Wastewater Rate... 7 Table 3: CCME National Performance Standards... 8 Table 4: Water Licence Effluent Quality Requirements... 8 Table 5: Effluent Discharge Objectives for Ammonia and Phosphorus... 9 Table 6: Raw Wastewater Influent Characteristics (measured at Lift Station No. 5) Table 7: Re-characterization of Raw Wastewater Influent for Future Expansion Table 8: Annual Averages for Open Water Season(a) for Main Holding Lagoon Cell Sampling Locations Table 9: Anticipated Average Day Flow and HRT for 5, 10 and 20 Year Design Horizon Table 10: Main Lagoon Cell Holding Capacity and Storage Time for 5, 10 and 20 Design Horizons Table 11: Fiddler s Lake Treatment System Model Calibration Parameters Table 12: Fiddler s Lake Model Calibration Results Compared to Measured Historical Data for Table 13: Projected Population and Wastewater Production for 5, 10- and 20-Year Design Horizons Table 14: Projected Flow and Loads for Fiddler s Lake Treatment System Table 15: Projected Average Concentrations based on Historical Removal Rates for Lake F3 at APPENDICES Appendix A: Appendix B: Appendix C: Appendix D Appendix E Population Projections and Calculations Annual Water Balance Memo: Annual Runoff Field Measurement Data Phosphorous Study BOD 5 CBOD 5 Study

5 TABLE OF CONTENTS (Cont d) Page No. LIST OF ACRONYMS CCME MWWE NPS EDO BOD 5 CBOD 5 sbod 5 COD TSS NH 3 -N NO 3 -N + NO 2 -N TP TKN VSS TOC QA/QC Canadian Council of Ministers of the Environment Municipal Wastewater Effluent National Performance Standard Effluent Discharge Objective 5-day Biochemical Oxygen Demand 5-day Carbonaceous Biochemical Oxygen Demand 5-day Soluble Biochemical Oxygen Demand Chemical Oxygen Demand Total Suspended Solids Total Ammonia as Nitrogen Nitrate + Nitrite as Nitrogen Total Phosphorus Total Kjeldahl Nitrogen Volatile Suspended Solids Total Organic Carbon Quality Assurance/Quality Control

6 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Executive Summary EXECUTIVE SUMMARY Dillon Consulting Limited (Dillon) was retained by the City of Yellowknife (City) to complete a year long sampling program to respond to items D.15, D.19, and D.20 of the City s water licence issued by the Mackenzie Valley Land and Water Board (MVLWB). The report contained herein includes, but is not limited to the required information set out in Schedule 2, item 3 of the water licence, which states; The revised Fiddlers Lake Treatment System Plan shall include, but not be limited to the following: a) Discussion on the triggers and thresholds that will be employed to determine when an upgrade to the Fiddler's Lake treatment system is required, which shall include, but not be limited to: consideration to influent loadings (volume and concentration); effluent water quality; effluent loadings to receiving water bodies; treatment time within the system, and time requirements to complete any studies or design that supports the upgrade; b) Discussion of how ammonia and phosphorous treatment will be completed to meet the following discharge objectives: average concentration for ammonia of 5 mg/l (maximum of 10 mg/l), average concentration for phosphorous of 1 mg/l (maximum of 2 mg/l); c) Details, analysis of results, and recommendations from any wastewater treatment study, may include, but not limited to, a wetland performance study during cold weather and a lagoon pre-treatment study; and d) Details of a phosphorous study into the loadings into receiving water bodies and associated potential impacts. As in previously completed work, the Fiddler s Lake Treatment System performance was evaluated with a dynamic computational biological model using GPS-X software. Updated data sets collected from the year long sampling program were used to recalibrate this current model in order to predict process performance for future load conditions over the life of the facility (5, 10 and 20 year horizons), and to identify the triggers and thresholds indicating the need for upgrades to the treatment system (as required per Schedule 2, item 3a of the water licence). The triggers were assessed on the basis of projected treatment performance against the water license criteria for Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD 5 ) and effluent discharge objectives (EDOs) for ammonia and phosphorus, in accordance with the Canadian Council of Dillon Consulting Limited September Project Number: i

7 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Executive Summary Ministers of the Environment (CCME) Canada-Wide Strategy for the Management of Municipal Wastewater Effluent (MWWE). The results of the GPS-X modelling projected higher average contaminant concentrations for decant as the population and loading into the lagoon increases over the 20 year period. Accordingly, the predicted future TSS and BOD 5 concentrations in the effluent will be greater than those currently reported, however they will remain within the effluent quality requirements set forth in item D.2 of the water licence and well below national performance standards. The ammonia concentration will also be well below the EDO average concentration (5 mg/l) as stated in water licence Schedule 2, item 3b. Ammonia concentration at the compliance point F3 is expected to be below the CCME threshold for acute toxicity of ammonia-nitrogen over the 20 year period, however it may exceed the threshold if discharge occurs after spring break-up without some time for treatment. Ammonia concentrations will likely exceed the threshold EDO acute concentration (10 mg/l) during fall i.e. (mid-october). Currently, the Total Phosporus (TP) concentration exceeds EDOs and is anticipated remain greater than the water licence EDO maximum concentration (2 mg/l) over the 20 year period. The historical removal rate of TP in the lagoon system is estimated to be 22.6 %, hence a supplemental strategy should be considered to reduce total phosphorus concentrations, as recommended in Schedule 2, item 3b. At present, the Fiddler s lake lagoon system meets all the waste disposal requirements set forth in the City s water licence, and will continue to be in compliance for the duration of the current Water Licence term (expires May 30, 2022). The phosphorus and ammonia EDOs represent objectives to be achieved over time, and are not currently strict regulatory requirements. As a result, supplemental strategies for phosphorus and ammonia removal may be required in future Water Licences. A risk-assessment for downstream Phosphouslevels in Great Slave Lake could be used to determine the impact onteh environment, and whether or not there is a need for corrective measures. Contingent upon the results, batch chemical treatment for Phosphorus precipitation is identified as a potential solution for phosphorus reduction in the lagoon. For ammonia reduction, a year-round hybrid fixed-film biomass system could be implemented in order to reduce the load on the wetland. Dillon Consulting Limited September Project Number: ii

8 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 1 INTRODUCTION The City of Yellowknife operates a lagoon and wetland sewage treatment facility at Fiddler s Lake (commonly known as Fiddler s Lake Lagoon ) under the regulations of the water licence issued by the Mackenzie Valley Land and Water Board. This facility is currently operating under the water licence MV2009L issued on June 2, 2010 and expires on May 30, The renewed water licence contained a number of conditions that required additional information for the Fiddler s Lake Treatment System to be collected within the two years following the issuance for the water licence. During the course the sampling campaign, inconsistent values for the measured raw sewage volumes were observed at one of two pump stations feeding the treatment system. This challenge caused a significant delay in data collection, however, a solution was defined and all essential data was collected and compiled to fulfill the conditions of the water licence. These additional requirements are included the following studies as stated in items D.15, D.19 and D.20 of the water licence. The following sections of the licence provide a summary of the reporting requirements: D. 15 The Licensee shall by March 31, 2012, submit to the Board for approval, a revised Fiddler s Lake treatment system plan that shall include, but is not limited to, the information as set in Schedule 2, item 3, included in this License. Schedule 2, item 3 The revised Fiddlers Lake Treatment System Plan shall include, but not be limited to the following: a. Discussion on the triggers and thresholds that will be employed to determine when an upgrade to the Fiddler s Lake treatment system is required, which shall include, but not be limited to: consideration to influent loadings (volume and concentration); effluent water quality; effluent loadings to receiving water bodies; treatment time within the system, and time requirements to complete any studies or design that supports the upgrade; b. Discussion of how ammonia and phosphorous treatment will be completed to meet the following discharge objectives: average concentration for ammonia of 5 mg/l (maximum of 10 mg/l), average concentration for phosphorous of 1 mg/l (maximum of 2 mg/l); c. Details, analysis of results, and recommendations from any wastewater treatment study, may include, but not limited to, a wetland performance study during cold weather and a lagoon pre-treatment study; and d. Details of a phosphorous study into the loadings into receiving water bodies and associated potential impacts. Dillon Consulting Limited September 2014 Project Number:

9 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report D. 19 The Licensee shall within 18 months of issuance of this Licence, submit to the Board for approval, a report that includes, but is not limited to: a) Occurrence and generation of algal blooms within the Sewage Disposal Facilities; b) The associated impacts of seasonal changes in ph; c) Evaluation of mitigative measures to achieve water quality compliance at SNP station 0032-F3; and, d) An implementation plan and schedule for mitigative practices, if required. D. 20 The Licensee shall complete a one year long characterization study of sewage effluent in accordance with the Canadian Council of Ministers of Environment s 2009 Strategy for Treatment of Municipal Wastewater Effluent. The Licensee shall submit to the Board for approval a report of the Sewage effluent study by March 31, On September 27, 2010, the City issued a request for proposals (RFP) to provide professional engineering services to complete the tasks listed above under the project Fiddler s Lake Treatment System Studies and Management Plan. Dillon was awarded the contract to complete this work in January To date, both the year long sampling program and assessment report for the ph spike investigation at the compliance point have been completed. The current report describes the studies completed to provide options for future growth upgrades to the Fiddler s Lake Treatment System as per item D.15 of the water licence. 1.1 Objective of Study This report is intended to provide a revised treatment plan for the Fiddler s Lake treatment system in accordance with the effluent limits and discharge objectives for parameters of concern, set forth by the Canadian Council of Ministers of the Environment (CCME) Canada-Wide Strategy for the Management of Municipal Wastewater Effluent (MWWE). The revised plan will document the operational changes to be applied to the system in the event that observed effluent quality reaches critical threshold values. Alternative treatment options for ammonia and phosphorus will also be presented in order to achieve prescribed discharge objectives as stated in the City water licence. To ensure that the current and anticipated capacity of the lagoon system are met, the Fiddler s Lake treatment system will be evaluated using GPS-X software calibrated with operating data collected over the year-long performance survey. The recalibrated GPS-X model will estimate the future effluent quality at the compliance point downstream of the wetland over 5, 10 and 20 Dillon Consulting Limited September 2014 Project Number:

10 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report year periods in the life of the facility. The projected performance will be evaluated with respect to the water licence criteria in order to identify the triggers and thresholds that may indicate the need for upgrades to the Fiddler s Lake treatment system. The 5, 10, and 20 year design horizons will be estimated on the basis of per-capita hydraulic and mass loadings and population projections. Additional hydraulic and/or mass loading sources will be considered where possible, such as the impact of surface water inflow, algal activity and decay, or sediment disruption. For each of these time periods, the Fiddler s Lagoon system will be evaluated within the GPS-X model to identify lagoon treatment capacity, decanting period and flow rate, and wetland performance during the discharge period. Seasonal factors such as temperature will also be considered as they relate to biological activity and final effluent quantity and quality. Dillon Consulting Limited September 2014 Project Number:

11 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 2 BACKGROUND INFORMATION 2.1 Fiddler s Lake Wastewater Lagoon System The City currently uses an enhanced natural lagoon system (Fiddler's Lake) followed by a series of biofiltering wetlands to treat the municipality's wastewater (Figure 1). The lagoon is situated off Highway 3, approximately 6 km west of the Yellowknife airport and consists of three main ponds which act as a holding and pre-treatment area for the wastewater. The main lagoon cell (labeled F8, F7 and F6 east to west, collectively Fiddler s Lagoon ) is approximately 3.2 km long, and has an estimated total liquid volume capacity of 2.5 ML. Lift Station No. 5 and No. 6 receive wastewater from the collection system and discharge to the wastewater treatment system. Therefore, all inflow to the lagoon from the collection system is monitored by the flow meters in these two lift stations. Figure 1: Overview of Fiddler's Lake Treatment System The lagoon contents are seasonally discharged into a polishing wetland (lakes F5, F4 and F3, as shown in Figure 1). The decant period for 2011 was from September 6 to December 2, Sampling is performed at the decant structure during the entire decant period, and compliance requirements are met at the end of Lake F3 at SNP station 0032-F3. The treated water travels a further 13 km through the wetland before entering Great Slave Lake. Dillon Consulting Limited September 2014 Project Number:

12 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 2.2 CCME Strategy for Managing Municipal Wastewater Effluent in the North The Canadian Council of Ministers of the Environment (CCME) has developed a Canada-wide Strategy for Managing Municipal Wastewater Effluent (MWWE) in an attempt to manage water quality and quantity more sustainably (CCME, 2009). The Strategy aims to provide a harmonized national framework for managing wastewater by addressing issues related to governance, wastewater facility performance, effluent quality and quantity, and infrastructure needs. However, due to the extreme climatic conditions and remoteness of the Far North, it was determined that exceptional consideration was necessary in order to produce viable guidelines reflective of the issues faced in the Northern communities. The Far North was therefore given a 5-year window to conduct research in order to develop feasible standards aimed at protecting human and environmental health. The MWWE is currently being formed into the Wastewater Systems Effluent Regulations (WSER) by Environment Canada, and the following interim measures currently apply to northern wastewater facilities: Effluent quality requirements in existing authorizations will continue to apply; For compliance, monitoring and reporting requirements referenced in current authorizations will be retained; A risk-based approach will continue to be used to manage municipal wastewater effluent; The standards in use in current permits in the North will be retained; Further research will be conducted within the next five years to identify the factors that affect performance of lagoons and wetlands in the North and how lagoons and wetlands can be improved; and Once adequate information is available within the five year period, National Performance Standards for northern conditions will be developed. All new and upgraded wastewater facilities are required to meet the National Performance Standards immediately. Existing facilities will be required to meet the standards within a number of years, depending on the level of risk. Implementation of the National Performance Standards will be based on risk, available funding and financial sustainability. Additionally, jurisdictions may establish more stringent limits than the National Performance Standards. Where needed, site-specific Effluent Discharge Objectives will address specific substances that are of concern to a particular discharge or environment. Implementation of these standards and objectives will be based on risk over a maximum time period of 30 years. Hence, for the purpose of this study, the National Performance Standards are presented in the context of guideline objectives to be met rather than strict regulatory requirements. Dillon Consulting Limited September 2014 Project Number:

13 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 3 PROJECTION CRITERIA Yellowknife has experienced a steady growth in its population during the start of the 21 st century until a slight decline during 2005 and For the purpose of this report, the 5, 10 and 20 design horizon population projections for Yellowknife were extrapolated from the records obtained from the Northwest Territories Bureau of Statistics. 3.1 Population Growth The Northwest Territories Bureau of Statistics census data included recorded populations for the city from 2001 to Population values were predicted up to the year 2031 using a linear growth rate that was determined from the population values recorded by the Bureau (Refer to Appendix A for additional calculations and data). The calculated growth rate for this period was 0.75 % per year, versus a national average growth rate of 1.2% reported by Statistics Canada in Long term population forcasts anticipate significant growth in future years, hence all calculations have been done assuming a growth rate of 1.2% in order to increase the sensitivity of this analysis. Figure 2Error! Reference source not found. below illustrates the trend in population over the lifetime of the facility. The calculated population predictions for 2016, 2021 and 2031 are shown in Table 1 and are based on a linear annual growth rate of 1.2%. Population Year Figure 2: Historical and Future Population Growth Trends at 1.2% per Annum Dillon Consulting Limited September 2014 Project Number:

14 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Table 1: Predicted Population for Project Design Horizons: Years 5, Year 10 and Year 20 Project Year Year Population Predicted , , , Sewage Generation Rates The amount of sewage generated can be assumed to be proportional to the amount of water consumed. Generally, the following formula (Department of Municipal and Community Affairs, Government of the Northwest Territories) is used to predict water consumption in Northern communities greater than 10,000 people that have a piped distribution network: ( ) Based on the consumption model, the sewage production would be 450 l/cap/d; however, a bestfit linear regression against measured sewage production for the years 2001 to 2012 produced a consumption rate of L/cap/d. For an even more conservative estimate, a consumption rate was determined using the highest wastewater generation rate observed over the past 5 years to predict the wastewater flow rates for the future conditions. This rate was determined to be L/cap/d as observed in In comparison, during the year of monitoring (2012), a generation rate of 409 L/cap/d was observed. From this, the annual sewage production for the estimated population in 2016, 2021 and 2031 (Table 1) were calculated and are tabulated below. Table 2: Predicted Wastewater Production for Design Horizon Year 5, 10 and 20 based on L/c/d Resdential Wastewater Rate Project Year Year Sewage Produced (m 3 /a) Sewage Production Rate (m 3 /d) ,129,986 8, ,322,347 9, ,743,261 10,254.8 For each year, the lagoon system will be required to treat this volume of sewage. In addition to the sewage volume, annual water balance (runoff, precipitation and evaporation) contribute water to the holding lagoon which further reduces the holding capacity; however, as the Dillon Consulting Limited September 2014 Project Number:

15 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report catchment area is fixed, the net contribution due to runoff is not expected to change from historical averages for the period considered in this study. The annual runoff collected by the holding lagoon was reported in a Monthly Water Budget in 2012 using drainage area mapping determined in a previous study (Dillon, 2007) and information provided by the City of Yellowknife. The average annual calculated runoff volume was approximately 404,000 m 3, ranging from 0 (during winter months) to 80, ,000 m 3 (July September). (Refer to Appendix B for details). 3.3 Current Effluent Limits The CCME strategy requires that all facilities achieve the National Performance Standards for effluent quality and develop and manage site-specific effluent discharge objectives (EDOs). In particular, the NPSs address pollutants common to most wastewater discharges such as BOD 5 and TSS. These NPSs are listed in Table 3 below, and represent the minimum effluent quality requirements for all wastewater systems that discharge to surface water. The Fiddler s Lagoon system does not accept other deleterious substances (e.g., industrial discharges) and, with regard to contaminants of concern, is not expected to deviate significantly from typical municipal wastewater. Table 3: CCME National Performance Standards Parameter Concentration (mg/l) Total Suspended Solids, TSS 25 5-day CBOD 5 25 Total Chlorine Residual, TRC 0.02 Accordingly, Part D of the City s current water licence issued by the Mackenzie Land and Water Board on June 2, 2010 sets forth conditions applying to waste disposal with which the Fiddler s Lake Treatment System must comply. These conditions include specific wastewater effluent limits and effluent discharge objectives (EDOs) at the compliance point (labelled 0032-F3) located at the outlet of Lake F3. The current effluent quality requirements as stated in Part D.2 of the water licence are listed in Table 4 below. The EDOs outlined in the water licence (Schedule 2, item 3b) for ammonia and phosphorus are listed in Table 4. Table 4: Water Licence Effluent Quality Requirements Parameter (units) Maximum Average Concentration (a) Maximum Grab Sample Fecal Coliform (FC per 100 ml) day Biochemical Oxygen Demand, BOD (b) 5 (mg/l) Dillon Consulting Limited September 2014 Project Number:

16 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Parameter (units) Maximum Average Concentration (a) Maximum Grab Sample Total Suspended Solids, TSS (mg/l) ph (ph units) 6 to 9 6 to 9 Oil and Grease No visible sheen Static pass/fail bioassay test for Acute Toxicity Rainbow Trout and Daphnia Magna whereby 70% survival is considered a pass. Notes: (a) Average concentration is the discrete average of four (4) consecutive analytical results, or if less than four analytical results, the discrete average of the analytical results collected during a batch decant. (b) The CCME Strategy uses carbonaceous biochemical oxygen demand (CBOD 5 ) as an effluent parameter rather than the traditional total BOD 5 due to concerns surrounding the effect of nitrogenous oxygen demand included in the BOD 5 measurement. Table 5: Effluent Discharge Objectives for Ammonia and Phosphorus Parameter (units) Average Concentration (a) Maximum Concentration Total Ammonia as Nitrogen, NH 3 -N (mg/l) 5 10 Total Phosphorus, TP (mg/l) Notes: (a) Average concentration is the discrete average of four (4) consecutive analytical results.or if less than four analytical results, the discrete average of the analytical results collected during a batch decant. It should be noted that the CCME MWWE guideline limits for TSS and CBOD 5 are slightly less stringent than those stated in the water licence for the facilty. However, the water licence requires the measurement of BOD 5 rather than the more sensitive CBOD 5 measurement required by the CCME MWWE guideline document. It should also be noted that the NPS for TSS can exceed 25 mg/l if the exceedance is caused by algae. The water licence TSS discharge limit (20 mg/l) does not take into account the potential impact of algae. The following sections of this report will illustrate where the Fiddler s Lake Treatment System is meeting the guideline limits for expected effluent over the life of the facility. However, it is important to note that the CCME guidelines for discharge objectives represent values to be attained over time, rather than static regulatory limits. Dillon Consulting Limited September 2014 Project Number:

17 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 4 FIDDLER S LAKE TREATMENT SYSTEM BIOLOGICAL MODELING The City of Yellowknife discharges municipal sewage to a holding lagoon that is seasonally decanted into a wetland system prior to discharge to Great Slave Lake. Sewage treatment performance of the Fiddler s Lagoon system, as it is collectively known, was modeled with a computational software package (GPS-X). The purpose of modeling the system was to provide estimates of future treatment performance based on historical data. The process of modeling the system consisted of historical data gathering, model calibration using historical data, and treatment estimation under projected future conditions using the calibrated model. 4.1 Wastewater Flow and Load The raw wastewater was sampled at Lift Station No. 5, the larger of the two final lift stations that deliver wastewater directly to Fiddler s Lake Treatment System, a total of 12 times throughout the 2011 sampling program. The quality of the grab samples were compared to the standard literature values for municipal raw wastewater (Metcalf and Eddy, 4 th ed., 2003). The mass loading and unit loading per capita were calculated from the measured average concentrations using the following additional data: Population: 20,248 (2011, Northwest Territories Bureau of Statistics, 2011) Raw Stored Wastewater Volume: 2,291,638 m 3 (measured from the end of decant, December 2, 2010 to start of decant, September 6, 2011) Average Raw Wastewater Flow: 8,213.8 m 3 /d (based on 279 days for holding capacity of the main holding lagoon from the end and start of the 2010 and 2011 decant period). Average Annual Raw Wastewater Flow: 8,381.4 m 3 /d (based on the 2011 annual wastewater generation of 3,059,084 m 3 per year excluding runoff). Lagoon Inflow: Including runoff, and using the more conservative annual flow of 8,381.4 m 3 /d using meter estimates, the flow increases to 9,488.3 m 3 /d (including 404,000 m 3 of annual runoff). Table 6 on the next page provides the average measured concentrations and calculated mass loadings and unit loadings based on the 2011 population (20,248) and average raw wastewater volume and flow as listed above. Dillon Consulting Limited September 2014 Project Number:

18 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Table 6: Raw Wastewater Influent Characteristics (measured at Lift Station No. 5) Parameter Measured Average Conc. (a) [mg/l] Mass Loading (b) [kg/d] Unit Loading (b) [g/cap d] Typical Unit Loading (c) [g/cap d] Range Average Total Suspended Solids, TSS 291 2, Day Biological Oxygen Demand, BOD , Chemical Oxygen Demand, COD 431 3, Ammonia as Nitrogen, NH 3 -N Total Kjeldahl Nitrogen, TKN Total Phosphorus, TP Soluble Orthophosphate as P NA (d) NA (d) Notes: (a) Average concentrations were calculated based on 12 samples collected from Lift Station No. 5, once in February 2011 and 11 times between early June and early November (b) Average mass loads and unit loadings were based on the daily measured parameter concentration and total influent flow rate from both LS5 and LS6. (c) Obtained from Metcalf & Eddy, 4 th ed, (d) Not reported in Metcalf & Eddy, 4 th ed., With the exception of total phosphorus, the calculated unit loadings for the parameters of concern were within the typical ranges for piped raw wastewater. The TP unit loading was slightly lower than the typical range, with unit loading rate of 2.31 g/capita d. The calculated unit loading for ammonia as nitrogen (NH 3 -N) unit was slightly above the higher end of the typical range with TKN falling within the normal range. The higher ammonia fraction in the TKN may be due to a large fraction of wastewater originating as septic system collection. The unit loading for TP was adjusted upward from that actually recorded for the purpose of modeling and for estimating future lagoon requirements to more conservative and typical unit loading values. The TP unit loading for future loading scenarios was increased from the measured 2.31 g/capita d to the typical literature value of 3.28 g/capita d (Metcalf and Eddy, 4 th ed. 2003) 1. Table 7 on the next page lists the resulting mass loadings and concentrations projected for the 5, 10 and 20 year design horizons based on the following population and wastewater flow estimates. 1 Consequently, as current TP values exceed EDO thresholds, increasing the unit loading to the more conservative typical literature value does not change the outcome of this report. Rather, it is intended to reflect anticipated growth rates for future planning purposes. Dillon Consulting Limited September 2014 Project Number:

19 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Parameter Table 7: Re-characterization of Raw Wastewater Influent for Future Expansion Unit Loading [g/capita d] 5 Year Design Horizon Year Design Horizon Year Design Horizon 2031 Population = 20,717 Population = 21,990 Population = 24,776 Mass Load [kg/d] Conc. [mg/l] Mass Load [kg/d] Conc. [mg/l] Mass Load [kg/d] Conc. [mg/l] TSS , , , BOD , , , COD , , , NH 3 -N TKN TP Soluble Orthophosphate as P Historical Performance of Treatment System Historical operating and performance data for the main holding lagoon and wetland was collected for the 2011 year based on the sampling program. The historical operating and performance data included contaminant concentrations as measured at five sampling locations located within the main holding lagoon cell (FID01 FID05), at the control structure (F6), along the wetland lakes (Lake F5, Lake F4 and Lake F3 middle) and at the compliance point immediately downstream of the wetland lake, Lake F3 (Lake F F3). Samples were taken along the direction of flow in the main holding lagoon cell to develop an understanding of the treatment performance within the main holding lagoon cell. The measured sampling results are shown in Table 8 on the next page. Dillon Consulting Limited September 2014 Project Number:

20 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Table 8: Annual Averages for Open Water Season(a) for Main Holding Lagoon Cell Sampling Locations ph, Lab Parameter Units Sampling Location ph, Field (b) (Surface) Temperature (b) (Surface) DO (b) (Surface) ph units ph units FID01 FID02 FID03 FID04 FID05 Decant (7.16) ºC 13.5 (13.8) mg/l 0.58 (0.91) 7.25 (7.30) 12.6 (14.2) 1.02 (1.36) 7.30 (7.35) 13.8 (14.1) 1.87 (2.09) 7.32 (7.40) 14.1 (14.2) 2.00 (2.41) 7.31 (7.43) 13.5 (14.4) 2.09 (2.32) Total Alkalinity mg/l TSS mg/l VSS mg/l BOD 5 mg/l sbod 5 mg/l COD mg/l NH 3 -N mg/l TKN mg/l NO 3 + NO 2 as N mg/l TP mg/l Soluble Orthophosphate as P mg/l Notes: (a) Open water season includes the water quality data and measurements from the June 7, 2011 to October 13, 2011 sampling campaigns. (b) Average for the entire depth of the lagoon. The average for the first 2 m below surface are shown in brackets. Averages shown for the decant are only for the surface. 4.3 Holding Capacity The holding capacity of the lagoon and the resulting flow rate during decant determine the hydraulic retention time (HRT) in both the holding lagoon and the wetland system, respectively. Bathymetric surveys for the Fiddler s Lagoon System completed in 2011 estimated the holding lagoon capacity to be 2,294,126 m 3 of working volume, based on pre-decant levels. In comparison, the reported wastewater inflow during the holding period of December 2, 2010 to the beginning of the 2011 decant on September 6, 2011 was determined to be 2,291,638 m 3 as flows measured at the two lift stations. This represents an average flow rate of 8,213.8 m 3 /d over Dillon Consulting Limited September 2014 Project Number:

21 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 279 days. The average runoff and evapotranspiration results in additional net volume added to the holding lagoon each year. (Refer to Appendix B for details.) It is assumed that the runoff is held by the lagoon prior to the decant season as the spring thaw and most of the non-freezing precipitation occur prior to the decanting season. Hence, using the recorded sewage volume, and conservatively adding the average net inflow due to runoff, the resulting total volume is 2,695,638 m 3 in the F8, F7, F6 sewage lagoon. Based on the two volumes presented, there is a difference of 15% from the bathymetric estimate versus the sum of inflow and raw wastewater estimate. These values appear to be in agreement, given the potential errors on bathymetric survey granularity. Therefore, 2,695,638 m 3 will be assumed to be correct, as it is subject to less measurement error. During the decanting season, the wetland system receives the volume held between decant periods plus inflow due to raw sewage displacement in the holding lagoon. This results in the total decant flow rate. The estimated decant flow rate into the wetland for 2011 was 26,342 m 3 /day based on the following: Total volume of the lagoon is 2.69 million m 3 (including runoff), working volume is 2,29 million m 3 ; Decanting period is from September 6 to December 2, 2011 (approximately 87 days); Raw sewage inflow during decant displaces 8,213.8 m 3 /d on average. The volume of the wetland is estimated from the results of the pre-decant bathymetric surveys (taken on July 13, 2011) and interpolated elevations. The bathymetric information is based on GPS locations and depth measurements, as well as interpolated depths based on shore slope. Accordingly, the total volume of the wetland prior to the 2011 decant was determined to be 1,373,458 m 3, with a total surface area of 1,583,719 m 2. Based on this information for the 2011 conditions, the estimated hydraulic retention time in the wetland lakes is approximately 52 days at a decant flow rate of 26,341 m 3 /d. The resulting decant flow rate to the wetland for each project year, assuming average net runoff collected by the lagoon, is shown in Table 9 on the next page, along with the projected wetland hydraulic retention time (HRT). For the 2021 and 2031 scenarios, the effective HRT of the wetland is increased. This is due to the longer decant commencing earlier in the year, likely during or immediately after the spring thaw. Dillon Consulting Limited September 2014 Project Number:

22 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Table 9: Anticipated Average Day Flow and HRT for 5, 10 and 20 Year Design Horizon Project Year Year Decant Flow Rate (m 3 /day ) Wetland HRT (days) , , , It can be observed that the wetland HRT for the 2011 season (52 days) was over half that of the lagoon decant duration (87 days). As sewage production and flow rate increases, the hydraulic retention time of the lagoon is reduced (volumetric capacity is met sooner), requiring an earlier decant start date and longer decant times. Further, the decant rate into the wetland is progressively decreased, resulting in longer HRTs in the wetland. 4.4 Projected Holding Capacity for Project Years 5, 10 and 20 The actual recorded 2011 holding duration of the lagoon is shown in Table 10 below, compared to estimated holding durations for future wastewater generation rates in years 2016, 2021, and Average net runoff to the holding lagoon is assumed to be constant as noted earlier, and as such in not included in the decant flow rate calculation. Project Year Table 10: Main Lagoon Cell Holding Capacity and Storage Time for 5, 10 and 20 Design Horizons Year Wastewater Produced excluding Runoff (m 3 ) Anticipated Decant Start Date Assumed Decant Finish Date Holding Time (days) Decant Time (days) Average Decant Flow Rate (m 3 /d) ,059,084 Sept 6 Dec , ,129,986 Aug 26 Dec , ,322,347 Aug 10 Dec , ,743,261 July 13 Dec ,190 Dillon Consulting Limited September 2014 Project Number:

23 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 5 MODEL CONSTRUCTION AND CALIBRATION The Fiddler s Lake Treatment System was simulated with a steady state computational model to estimate future treatment performance under the projected population-based volume and loading scenarios. The model was calibrated using performance data collected from the year long sampling program. The calibration process provided model parameters to fit the simulation to the historic performance of the lagoon system as measured. Future treatment conditions were projected on the basis of population growth and the impact on the holding lagoon residence time and decanting period. These projected loadings were simulated using the kinetic parameters obtained through calibration. 5.1 Calibration Dataset The historical operating data from the yearlong sampling program indicates that some nitrification may occur in the holding lagoon. The average ammonia concentration for the raw wastewater entering the lagoon was 28.4 mg/l whereas the average ammonia concentration for the open water season at the decant structure was 10.6 mg/l. However, most of the nitrification occurs in the wetland (average concentration at the Lake F3 compliance point was 1.2 mg/l). Dissolved oxygen concentrations, ph and temperature within the main holding lagoon cell were measured at the five equidistant locations along the entire length of the lagoon and at 0.5 m depths at each sampling location. Appendix C summarizes the collected field measurement data for ph, temperature, DO, TSS and BOD 5. For the purpose of the model calibration, a depthweighted average DO concentration of 0.91 mg/l was used for the active zone (the first 2 m from liquid surface for sampling location FID01). The remaining four sampling locations along the lagoon used the following annual average DO concentrations for the entire liquid depth of the lagoon: 1.02 mg/l, 1.87 mg/l mg/l and 2.09 mg/l, respectively. 5.2 Model Configuration Two approaches were considered for the purpose of constructing a steady state computational biological model. An empirical lagoon model was considered for the computational biological model; however, the empirical model available in GPS-X does not provide a means to simulate nitrification, nor does it simulate the effects of dissolved oxygen on the biomass. It was decided to use a calibrated activated sludge model for both the holding lagoon to enable more detailed modeling of the biological process, including nitrification. The activated sludge model represented by the system of equations collectively described in literature as ASM2d, and as implemented in the GPS-X simulation software, was used for the lagoon computational model. Dillon Consulting Limited September 2014 Project Number:

24 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report The holding lagoon was modeled as a series of plug-flow reactors followed by solids removal steps. This allowed the software to model the biomass treatment as well as the settling due to residence time within the lagoon. The sampling program identified an active zone up to FID01 that provided most of the BOD 5 reduction. The average hydraulic volume of the lagoon active zone (defined as the lagoon volume between the raw wastewater influent location and the sampling point FID 01) was estimated to be 173,552 m 3 from topographical data and average depth measurements (average of pre-decant at highest liquid level and post decant under ice conditions). At an average 2011 wastewater influent flow rate 8,213.8 m 3 /d, this active zone volume is equivalent to 21 days of retention time. Some dilution within the holding lagoon occurs as a result of collected runoff, precipitation, and evapotranspiration processes. The net average contributes 404,000 m 3 annually to the holding lagoon (Appendix B). The runoff is added to the biological model after the active zone and into the main holding lagoon volume to simulate the effect of dilution and reduced hydraulic residence time (HRT) within the primary portion of the lagoon. The holding lagoon biological model configuration is shown schematically in Figure 3. Figure 3: Fiddler s Lake Treatment System Lagoon Cell Biological Model Configuration The holding lagoon active zone is split into three plug-flow reactors followed by solids settling steps. The three reactors have physical volumes that correspond to 1-day, 10-day, and 10-day HRT respectively for a total of 21 days HRT as estimated earlier. The overall HRT of the holding lagoon was 279 days during the sampling program as measured between end of decant and start of the next decant. The model kinetic parameters were identified through calibration to match the measurement results observed during the sampling program.the biomass within the active zone is expected to work as a single-sludge system, that is, with the same rate of treatment. Each plug flow reactor within the active zone was configured identical model kinetic parameters to achieve a concentration profile similar to the analysis at sampling point FID01. The rest of the holding lagoon is represented by the final plug flow reactor and operates under Dillon Consulting Limited September 2014 Project Number:

25 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report different kinetic parameters to provide a concentration profile similar to the 2011 average decant concentrations at the control structure at the end of Lake F Calibration Results Model calibration consists of combining a complete set of data inputs (e.g., 2011 wastewater influent flow and load, dissolved oxygen, decanting flow, hydraulic volume, surface area and depth) and adjusting the biological kinetic parameters until the model generates output consistent with the historical effluent during seasonal decanting. It is assumed that discharge to Great Slave Lake outside of the decanting season would be due to runoff and therefore represent a small proportion of the annual mass load. The operating data for the 2011 decant period, as provided by the City of Yellowknife for locations F6 and F3, was used to calibrate the sewage treatment model for current conditions. Kinetic parameters that were adjusted from default model values in order to achieve the calibrated results are summarized in Table 11. Table 11: Fiddler s Lake Treatment System Model Calibration Parameters Model Kinetic Parameters Units Calibration Value Lagoon Active Zone (Inlet to Sampling Point FID01) Heterotrophic Growth Rate 1/d Oxygen Half Saturation Coefficient go 2 /m Autotrophic Growth Rate 1/d Autotrophic Half Saturation Coefficient go 2 /m Holding Lagoon (Sampling Point FID01 to Decant Structure F6) Heterotrophic Growth Rate 1/d 0.25 Oxygen Half Saturation Coefficient go 2 /m Heterotrophic Lysis and Decay Rate Constant 1/d 0.4 Autotrophic Growth Rate 1/d Autotrophic Half Saturation Coefficient go 2 /m Autotrophic Decay Rate 1/d 0.15 Table 12 on the next page summarizes the calibration results for the steady state simulation as compared to measured average target data values. The computational model provides good results (within 10% of measured average) for all parameters at the decant location except for TSS and TKN. The deviation associated with total suspended solids is theorized to be due to the potential re-entrainment of solids at the final lagoon location due to the upflow current during decanting. This might be mitigated by de-sludging the lagoon in an area around the decant location which is constricted. The disagreement in TKN is more complex and is expected to be due to the limitation of the model in predicting the effect of organic nitrogen release from the lagoon sludge. It is important to note that TKN is not a regulated parameter. Dillon Consulting Limited September 2014 Project Number:

26 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report Table 12: Fiddler s Lake Model Calibration Results Compared to Measured Historical Data for Open Water Season Stream/ Parameter Measured Average Historical Value [mg/l] Calibrated Model [mg/l] Relative Error [%] Lagoon Active Zone (Inlet to Sampling Point FID01) BOD TSS TKN NH 3 -N TP Holding Lagoon (Sampling Point FID01 to Decant Structure F6) BOD TSS TKN NH 3 -N TP Estimating Future Treatment Conditions The calibrated model was used to estimate wastewater treatment performance of the main holding lagoon and wetland under projected 5, 10 and 20-year design horizon conditions for wastewater influent flow and mass loadings as identified in Table 7. Table 13 lists the projected population and wastewater production for the 5, 10 and 20-year design horizons. Table 13: Projected Population and Wastewater Production for 5, 10- and 20-Year Design Horizons Design Horizon Population Annual Wastewater Production Rate (a) [m 3 /d] 5-Year (2016) 20,717 8, Year (2021) 21,990 9, Year (2031) 24,776 10,254.8 Notes: (a) Based on a wastewater generation rate of L/capita/d calculated based on the 2011 annual average. Concentration results from the main holding lagoon model were used as inputs for the wetland model. The 5, 10- and 20-year holding lagoon retention period and decant flow rate were estimated. The decant flow rate estimate was used as the 5, 10 and 20-year flow input to the wetland steady state model. Dillon Consulting Limited September 2014 Project Number:

27 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report The model results for calibration and 5, 10 and 20-year projected lagoon system effluent are summarized in Table 14. Parameter Table 14: Projected Flow and Loads for Fiddler s Lake Treatment System Units Calibration (2011) 5-Year Projection (2016) 10-Year Projection (2021) 20-Year Projection (2031) Water Licence Limit (0032-F3) a Lagoon Effluent at Control Structure (F6) TSS mg/l (- 17.2) BOD 5 mg/l 43.1 (+ 10.2) NH 3 -N mg/l (- 0.3) TP mg/l 3.4 (- 1.4)* 3.6* 3.7* 3.7* 1 BOD 5 :N - 1:4 1:3.6 1:3.9 1:3.2 - Lagoon Volume m 3 2,291,638 2,291,638 2,291,638 2,291,638 Wastewater Inflow m 3 /d 8, , , ,254.8 Runoff m 3 404, , , ,000 HRT D Decant Period D Decant Start - Sept 6, 2011 Aug 26, 2016 Aug 10, 2021 Jul 13, 2031 Decant Stop - Dec 2, 2011 Dec 2, 2016 Dec 2, 2021 Dec 2, 2031 Decant Rate Flow m 3 /d 26,341 23,441 20,238 16,190 Notes: a Note: The water licence limits reflect criteria for the compliance point (0032-F3), not at the decant structure location (0032-F6). Values are shown here for comparison only. *Plant uptake of TP in the lagoon is not adequately modeled with the activated sludge process model, ASM2d. The holding lagoon residence time will be reduced from 279 days to 267, 252 and 223 days, respectively, as a result of the fixed holding lagoon capacity, annual runoff volume and the increase in raw wastewater flow. The decanting season is forced to start approximately 11, 26 and 55 days earlier, respectively, and last for 98, 113 and 142 days, respectively, resulting in less lagoon treatment and more dependence on the wetland polishing. The future decanting season is estimated to start as early July for the 20 year design horizon, depending on the amount of precipitation accumulated within the specific year. Increased precipitation could require the holding lagoon to start decanting shortly after the spring thaw. Table 15 lists the projected average concentrations for Lake F3 at compliance point (0032-F3) based on the historical measured removal rates. For earlier decant start times, it is anticipated that the wetland system Dillon Consulting Limited September 2014 Project Number:

28 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report may be fully active during the start period and be required to operate under lower decant flow rates. Therefore, the historic percent removal rates are expected to be conservative. Table 15: Projected Average Concentrations based on Historical Removal Rates for Lake F3 at Compliance Point (0032-F3) Parameter Units Historical Average Percent Removal 5-Year Projection (2016) Decant Lake F F3 10-Year Projection (2021) Decant Lake F F3 20-Year Projection (2031) Decant Lake F F3 Water Licence Limits (mg/l) TSS mg/l 89.9 (95.7) BOD 5 mg/l 89.1 (96.1) NH 3 -N mg/l 97.3 (96.9) TP mg/l 22.6 (22.0) 3.6* * * Notes: *Plant uptake of TP in the lagoon is not adequately modeled with the activated sludge process model, ASM2d. The value in parenthesis are the historical average percent removal for the open water season, June 7 October 13, Higher average contaminant concentrations are projected for decanting as population and loading into the lagoon system increases. Although the predicted TSS and BOD 5 will be greater than current levels, they will remain well below the NPSs of 25 mg/l and 25 mg/l, respectively, and below the water licence criteria at the compliance point 0032-F3. The ammonia concentration will also be well below the maximum average concentration (5 mg/l) EDO as stated in the water licence. The effluent concentration of ammonia at the compliance point is expected to be below the CCME threshold for acute toxicity of 180 mg/l for a ph of 7.02 and 10 mg/l for a ph of 8.5 for (Canada-wide Strategy for the Management of Municipal Wastewater Effluent, CCME). However, the ammonia concentration may exceed the threshold acute concentrations if discharge occurs after spring break-up without some time for treatment. Ammonia concentrations will likely exceed the threshold acute concentration during fall i.e. (mid-october). The TP concentrations are anticipated to be greater than the water licence EDO maximum average concentration (1 mg/l) and maximum grab sample concentration (2 mg/l) throughout the 20 year period. Albeit, it is worthy to note that the EDOs for TP and NH 3 are not strict regulatory requirements and as a result do not compromise compliance with the City s water licence. In summary, the Fiddler s lake lagoon system currently meets all the waste disposal requirements set forth in the City s water licence, and will continue to be in compliance for the duration of this licencing period (expires May 30, 2022). Threshold limits for TSS, BOD 5 and average NH 3 are not likely to be met over the 20-year period in consideration, however, a supplemental strategy Dillon Consulting Limited September 2014 Project Number:

29 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report for the reduction of TP concentrations in the system and NH 3 load on the wetland (as a function of earlier decant) may be required in the future. Dillon Consulting Limited September 2014 Project Number:

30 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 6 NUTRIENT REDUCTION IN COLD CLIMATES It is commonly understood that far northern ecosystems are nutrient limited (Yates, 2012) and in particular many aquatic systems are oligotrophic as a result of the limited natural nutrient and organic inputs. However, as previous study by Dillon (2012) have shown, the Fiddler's Lake Sewage Lagoon and wetland system processes large quantities of anthropogenic nutrient and organic inputs, with complex nutrient cycling processes that result in the release of ammonia and phosphorus under anaerobic conditions; and anaerobic mineralisation of organic material by sulphur bacteria. In temperate climates, these biochemical processes can occur year round with only relatively small fluctuations in seasonal metabolic activity. Conversely, in the Far North, the large seasonal variation in temperature, long periods of ice cover and availability of sunlight for photosynthetic activity tend to slow down these processes resulting in a large temporal and spatial variation in nutrient concentrations (Landers, 2012), as evidenced in the Fiddler's Lake Sewage Lagoon system. The projections presented in this study demonstrate the possible scenarios for regulatory (non-) compliance over the next 20 years, particularly regarding nitrogen and phosphorus levels. Not surprisingly, with population growth and increased load on the existing facility, this fate is inevitable and efforts must be made to reduce the overall nutrient load on receiving water bodies, or at least keep it constant in areas where compliance has already been achieved. To do so, nutrient reduction technologies must be considered on a case-by-case basis in order to optimize effluent quality. An overview of the technologies employed for cold region nutrient reduction is provided below. Nitrogen removal is often required before discharging treated wastewater to receiving water bodies. Commonly, reducing the concentration of nitrogen in wastewaters can be achieved through some variation of the two-step biological process known as nitrification and denitrification. Typically, this involves the conversion of ammonia into nitrite and nitrate (nitrification), and then its subsequent release into the atmosphere as harmless nitrogen gas (denitrification). In colder climates, this process is limited by varying cover, air and soil temperature, composition of vegetation and microbial communities, the presence of surface water and treatment area. Conventional methods for phosphorus reduction include the activated sludge process, which can be configured in some cases to optimize phosphorus removal to up to 0.1 mg/l (Landers, 2012), when followed by filtration. Another option for phosphorus removal involves the addition of ferric and magnesium salts, or alum to induce precipitation. Biological methods for phosphorus removal are also commonly used, which involve alternating anaerobic-aerobic cycles resulting in Dillon Consulting Limited September 2014 Project Number:

31 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report the accumulation of phosphates which can be removed from the system with excess sludge (Zeng, 2004). Andersson et al. (2005) offered a study of the the nitrogen and phosphorus removal performance of four large (20 28 ha) cold climate wetlands in Sweden, receiving effluent from conventional WWTP with varying degree of mechanical pre-treatment. Pre-treatment strategies consisted of biological and chemical treatment, settling and combinations of each. Interestingly, it was found that mean effluent concentrations for BOD 5 in all cases were very low, with no significant temperature dependency. Nitrogen removal was in the 23 39% range (for ammonia), but experienced clear seasonal variations in efficiency. Phosphorus removal was generally around 30%, with 90% removal efficiency observed in one particular wetland (Andersson et al., 2002). The aforementioned wetland was subjected to a tracer study for phosphorus which showed that a substantial fraction of the influent phosphorus in suspended solids settled close to the inlet of the wetland (Gunnarsson, 1997), (Andersson, 2002). In this particular case, chemical treatment was used to induce precipitation, and it is likely that the precipitation would have continued throughout the wetland with residues of the chemicals used in pre-treatment resulting in the exceptionally high removal efficiency. The study concludes by stating that the use of aluminumbased precipitation chemicals is preferable since the risk of phosphorus being re-released from the sediments is reduced. In the northern United States, the Houghton Lake, Michigan wetland system has been studied extensively since the 1970s and was one of the first natural wetlands to receive pre-treated wastewater in North America (Kadlec, Cuvellier, & Stober, 2010). This system has also successfully met treatment objectives in a cold climate setting. The natural system was shown to effectively treat the secondary wastewater entering the system. Another example from a treatment wetland in Minot, North Dakota, demonstrates excellent treatment following extended periods of freezing temperatures as low as 45 C (Hammer, 2002). This system experienced extensive pre-treatment through facultative ponds and averaged a BOD 5 removal rate of 27.2%, an ammonia removal rate of 46.8% for temperatures below 5 C. Although the Minot wetland system is a constructed surface flow wetland, it can provide some comparison in that it functions at an average yearly temperature of approximately 10 C, which reflects average summer temperatures at Fiddler s Lagoon. This system serves to highlight the importance of sustaining removals through extreme temperature fluctuations, and may be important for future considerations in more northern locations. Far northern treatment systems must also address the problem of shorter treatment periods due to long periods of ice cover and low availability of sunlight for photosynthetic activity. As a result, Dillon Consulting Limited September 2014 Project Number:

32 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report alterations to lagoon structure have been implemented at some treatment sites with the goal of increasing the useful contact time with nutrient reducing microorganisms. For example, in treatment wetlands throughout the Canadian far north, namely Arviat and Cambridge Bay, the use of berms and other structures have successfully been adopted to minimize wastewater preferential flow and increase residency time to allow for microbial uptake/transformation of nutrients in the wastewater (Kadlec, 2008). In the case of wastewater systems faced with compliance to low nutrient limits, a key consideration involves whether such limits are short- or long-term in nature. Often, regulations impose daily or short-term limits for nutrients; however, unlike acutely toxic substances, nutrients tent to have a latent impact on the ecosystem. Because of variation in daily influent nutrient loads, meeting stringent objectives may become problematic. Hence, it may be more realistic to consider compliance with nutrient limits over a longer term, i.e. annual objectives for compliance. 6.1 Current and Future outlook for Fiddler s Lagoon At present, the Fiddler s lake lagoon system meets all the effluent quality critera set forth in the City s water licence, and will continue to be in compliance for the duration of this current licencing period (expires May 30, 2022). The threshold limits for TSS, BOD 5 and average NH 3 are not likely to be exceeded over the 20 year period considered in this study. Although the current and predicted TP concentrations at the 0032-F3 compliance point exceed the water licence EDOs, no corrective action is presently required for the lagoon system to remain in compliance with the current water licence criteria. Supplemental strategies for the reduction of TP concentrations in the system and NH 3 load on the wetland (as a function of earlier decant) may be required to comply with future water licencing requirements. A risk-assessment for downstreamphosphouslevels in Great Slave Lake (at sampling point 0032-F1, Figure 1) would reveal whether or not there is a need for corrective measures. Alternative treatments and system upgrades could therefore be considered contingent upon the results of the risk-assessment. The following sections discuss treatment strategies to this end Phosphorus Reduction In order to achieve a reduction of TPconcentration, the precipitation of Phosphousthrough batch chemical treatment of wastewater by ferric chloride, aluminum sulfate or lime is commonly used. Precipitation could possibly be followed by annual dredging for the removal of local sludge accumulation. The overall effect would be a reduction of downstream TP load on the wetland. Such systems have been implemented with great success throughout North America for Dillon Consulting Limited September 2014 Project Number:

33 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report the control of municipal wastewater TP. Results have shown effluent quality from batch treated lagoons is comparable to or better than that achieved by conventional secondary treatment. Finally, the addition of chemicals to an existing lagoon via motorboat or mixing structure requires a relatively low capital investment and operates quite well within many existing lagoon configurations. Hence with the proper implementation, this strategy would provide a costeffective method of TP treatment for the Fiddlers Lake Treatment System. Accordingly, benchscale testing of phosphorus precipitation of the lagoon decant effluent is recommended to assess its feasibility. A summary report of a previous phosphorus study at the Fiddlers Lake Treatment System is given in Appendix D. Details into TP concentrations at various points throughout the treatment system are given along with associated potential impacts Ammonia Reduction The historical operating data from the yearlong sampling program indicates that some nitrification may occur in the holding lagoon, however, most of the nitrification occurs in the wetland. As demonstrated in Table 9, the holding lagoon is expected to provide fewer days of retention prior to decant as population and sewage production increase. As a result, the lagoon may begin decanting during spring thaw or early June. Currently, the wetland provides BOD, TSS polishing, nitrifies most of the ammonia, and consumes phosphorous load. A longer decant period may result in overloading the wetland which could compromise treatment in the future for nitrogen and phosphorous. In order to reduce the ammonia load entering the wetland, a year-round nitrification system could be implemented within the active zone of the holding lagoon. Hybrid fixed-film biomass systems have gained widespread acceptance in the engineering community as an economical new was to expand wastewater plant capacity and treatment levels without the need for new infrastructure. By simply adding a high surface area attached growth media directly into the lagoon to increase the amount of biomass available in the system, treatment levels for ammonia and total nitrogen can be greatly improved. There are several different kinds of synthetic media available for integrated fixed-film biomass systems, and even more different manufacturers of these media. Accordingly, a pilot-study is recommended to determine the optimal media and implementation of this technology for use at the Fiddlers Lake Treatment System Increase in Lagoon Retention Time In order to maintain the current level of treatment, both the holding lagoon and wetland would require a volume expansion equal to the population growth rate in order to ensure that the decanting season does not start earlier than September. However, in order to meet future effluent limits, particularly for ammonia and phosphorous, the level of treatment in the lagoon system Dillon Consulting Limited September 2014 Project Number:

34 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report must be improved. In the previous report to the City, it was indicated that the available expansion options (raising berm height or downstream expansion) were not practical and required land outside of the municipal boundary. These options were therefore discarded (Jacques Whitford, 2003). The analysis of this report finds nothing to contradict these conclusions and therefore excludes lagoon expansion as a viable option. Dillon Consulting Limited September 2014 Project Number:

35 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 7 CONCLUSIONS The GPS-X model provided insight into the treatment and performance capabilities of the Fidder s Lake Treatment System by projecting the effluent quality for the 5, 10 and 20 year horizons. The model results were used to identify the triggers and thresholds of the treatment system and to indicate when the need for upgrades to the Fiddler s Lake Treatment System was required. The triggers were assessed on the basis of projected treatment performance against the water license criteria for BOD 5, ammonia and phosphorus, in accordance with the Canadian Council of Ministers of the Environment (CCME) Canada-Wide Strategy for the Management of Municipal Wastewater Effluent (MWWE). Currently, the Fiddler s lake lagoon system meets all the waste disposal requirements set forth in the City s water licence, and will continue to be in compliance for the duration of this licencing period (expires May 30, 2022). The threshold limits for TSS, BOD 5 and average NH 3 are not likely to be met over the 20 year period considered in this study. Although the current and predicted TP concentrations at the 0032-F3 compliance point exceed the water licence EDOs, no corrective action is presently required for the lagoon system to remain in compliance with the current water licence criteria. Supplemental strategies for the reduction of TP concentrations in the system and NH 3 load on the wetland (as a function of earlier decant) may be required to comply with future water licencing requirements. To this end, a risk-assessment for downstream Phosphouslevels in Great Slave Lake would reveal whether or not there is a need for corrective measures. Contingent upon the results, batch chemical treatment for Phosphousprecipitation is recommended as a potential solution for phosphorus reduction in the lagoon. For ammonia reduction, a year-round hybrid fixed-film biomass system could be implemented in order to reduce the load on the wetland. Dillon Consulting Limited September 2014 Project Number:

36 Public Works and Engineering, City of Yellowknife Fiddler s Lake Treatment System Plan Final Report 8 REFERENCES Andersson, J. K. (2002). Four Large Wetlands - a comparison of treatment capacity in Swedish wastewater treatment wetlands. Uppsala, Sweden: VA-Forsk Report. Dillon. (2007). Expansion of Fiddler's Lagoon Treatment System Plant. Yellowknife, NWT: Dillon Consulting Limited. Dillon. (2009). Expansion of Fiddler's Lagoon Treatment System Plan. Yellowknife, NWT: Dillon Consulting Limited. Dillon. (2012). Fiddler's Lake Treatment System Studies and Management Plan: ph Compliance Point Assessment. Yellowknife, NWT: Dillon Consulting Limited. Dillon. (2014). Fiddler's Lake Treatment System Studies and Management Plan: Effluent Characterization Study. Yellowknife, NWT: Dillon Consulting Limited. Eddy & Metcalf. (2003). Wastewater Engineering: Treatment and Reuse. Toronto, ON: McGraw Hill. Gunnarsson, S. (1997). Accumulation of phosphorus in sediments in a wetland loaded with pretreated wastewater. Uppsala, Sweden: Department of Water Quality Management, Swedish University of Agricultural Sciences. Hammer, D. A. (2002). Low temperature effects on pollutant removals at Minot's wetland. In U. J. Mander (Ed.), Natural Wetlands for Wastewater Treatment in Cold Climates. (pp. 1-7). Boston: WIT Press. Kadlec, R. H. (2008). Wetland planning study, Cambridge Bay, Nunavut. Northern Territories Water Waste Association, Kadlec, R. H., Cuvellier, C., & Stober, T. (2010). Performance of the Columbia, Missouri treatment wetland. Ecological Engineering, Landers, J. (2012, January). How low can treatment plants go? Water Environment & Technology Magazine, Water Environment Federation, pp Yates, C. N. (2012). Performance assessment of arctic tundra municipal wastewater treatment welands through an arctic summer. Ecological Engineering, Zeng, R. J. (2004). Improved understanding of the interactions and complixities of biological nitrogen and phosphorus removal processes. Reviews in Environmental Science and Biotechnology, 3, Dillon Consulting Limited September 2014 Project Number:

37 APPENDIX A POPULATION PROJECTIONS and CALCULATIONS

38 Appendix A: Population Estimates % 0.75 % (historical) 1.00 % 1.20 % (National Average, 2011) 1.50 % 2.00 % Population Year Project Year Growth Rate Calendar Year 0.5 % 0.75 % 1.0 % 1.2 % 1.5 % 2.0 % Population records were obtained for the city from the Northwest Territories Bureau of Statistics. This census data from the Bureau included recorded populations for the city from 1996 to For the purpose of this study, population values were predicted up to the year 2031 using a linear growth rate that was determined from the population data recorded by the Bureau. Despite a slight decline in the population noted in 2005 and 2006, the growth rate for this period was determined to be 0.75 %. Due to variations between recorded population data between Statistics NWT and Statistics Canada, a sensitivity analysis was carried out making adjustments for predicted growth rate. The national average growth rate for 2011 was 1.2%.Comparing the above values to growth rates of 0.5 %, 1.0 %, 1.5 % and 2.0% illustrates the possible trends in population growth for the City of Yellowknife over the lifetime of the facility.

39 APPENDIX B ANNUAL WATER BALANCE MEMO: ANNUAL RUNOFF

40 MEMO TO: FROM: Matt Murdock, Corina Peach Igor Iskra, Roy Johnson DATE: February 3, 2012 SUBJECT: Fiddler s Lagoon Monthly Water Budget OUR FILE: This memo briefly describes the methodology and the results of the assessment of the monthly water budget for the watershed where the Fiddler s Lagoon is located. BACKGROUND DATA The following information was obtained for estimation the monthly water balance for the Fiddler s Lagoon. Precipitation Data for Yellowknife (# ) for ; Daily Temperature Data for Yellowknife (# ) for ; Runoff Data recorded at the Water Survey of Canada Baker Creek at outlet of Lower Martin Lake (#07SB013) ( ); and Evaporation Data by Pocket Lake Daily Evaporation Rates in mm, Penman Combination Method ( ). These data was provided by the Aboriginal Affairs and Northern Development Canada (AANDC) Water Resources Section and by Environment Canada. Based on discussions with the AANDC, it was recommended that runoff data obtained from Lower Martin Lake and evaporation data from Pocket Lake would be most representative of the subject area. However, evaporation data was typically collected from May to October each year with gaps in the record. Flow data also has many missing data that make them unreliable to use for continuous water balance calculations. Their use can be limited to model validation purposes only. The most reliable and available data for the study area is the continuous daily precipitation and air temperature. These data together with site latitude and soil characteristics and slopes were used in the water balance model. The drainage area to Fiddler s Lagoon was determined in our previous study (Dillon, 2007) with the use of 1:50,000 National Topographic System (NTS) mapping in conjunction with information provided by the City of Yellowknife. Contours and visual inspection information on the area shows that the terrain is undulating with small depressions and low lying areas that collect and store runoff. The drainage area was previously delineated and calculated to be 7.23 km 2. This area was used in the subsequent annual runoff calculations. 235 Yorkland Boulevard, Suite 800, Toronto, Ontario, M2J 4Y8 Phone (416) Fax (416)

41 Memo Re: Fiddler s Lagoon Monthly Water Budget February 3, 2012 /2 METHODOLOGY The Thornthwaite monthly water balance model (McCabe and Markstrom, 2007), developed by US Geological Survey, was used in this study. The model calculates the allocation of water among various components of the hydrological system based on methodology originally described by Thornthwaite (Thornthwaite, 1948; Mather, 1979; Wolock and McCabe, 1999). Inputs to the model are mean monthly temperature, monthly total precipitation and the latitude. The latitude of the location is used for the computation of day length, which is needed for the computation of potential evapotranspiration (ET). Several calibration parameters such as runoff factor, direct runoff factor, soil moisture storage capacity and maximum melt factor were adjusted in order to represent the local conditions. RESULTS All results of monthly model simulation are shown in tabular format in Appendix A. The graphical results of monthly potential ET, actual ET and runoff for Fiddler s Lagoon are presented on the Figure below. The summary of the water balance for is shown in the Table below. PET Precip AET Snow Storage Runoff Runoff Coef. Runoff Volume mm mm mm mm mm m 3 Jan ,338 Feb ,594 Mar ,574 Apr ,721 May ,175 Jun ,858 Jul ,401 Aug , Yorkland Boulevard, Suite 800, Toronto, Ontario, M2J 4Y8 Phone (416) Fax (416)

42 Memo Re: Fiddler s Lagoon Monthly Water Budget February 3, 2012 /3 Sep ,242 Oct ,391 Nov Dec TOTAL ,072 Our results on an annual scale are consistent with previous water budget studies in Northwest Territories and specifically in Yellowknife (Reid and Faria, 2004; Tyhee, 2011; Quinton and Hayashi, 2004). These studies suggest that average annual runoff ratio (annual runoff expressed as a percentage of the annual precipitation) ranges between 20% and 35 %, indicating that evapotranspiration is the dominant water loss factor in the area. Contours and visual inspection information of the area show that the Fiddler s Lagoon terrain is undulating with small depressions and low lying areas that collect and store runoff. That is why the low runoff ratio (19%) simulated by the water balance model is reasonable. As can be seen in the results presented in the Table, estimated runoff volume discharging from Fiddler s lagoon ranged from 0 (winter months) to 80, ,000 m 3 (July September). The average annual calculated runoff volume was approximately 404,000 m 3 and the average annual calculated runoff coefficient was These results are consistent with our previous results (Dillon, 2007). REFERENCES Dillon (2007) Expansion on Fiddler s Lagoon Treatment System Plan Assessment of Drainage Area and Annual Runoff Volumes, Memo prepared by Bill Dwyer. Mather J.R. (1979) Use of the climatic water budget to estimate streamflow, in Mather, J.R., ed., Use of the climatic water budget in selected environmental water problems: Elmer, N.J., C.W. Thornthwaite Associates, Laboratory of Climatology, Publications in Climatology, v. 32, no. 1, p McCabe G.J. and Markstrom S.L. (2007) A Monthly Water-Balance Model Driven By a Graphical User Interface, U.S. Geological Survey. Reid B. and Faria D. (2004) Evaporation studies in small NWT watersheds, Proceedings of a workshop Northern Research Basins Water Balance, IAHS Publ Quinton W.L. and M. Hayashi M (2004) The Flow and Storage of Water in the Wetland-Dominated Central Mackenzie River Basin: Recent Advances and Future Directions. CWRA Journal on Predicting Ungauged Streamflow in the Mackenzie Valley. Yellowknife, Northwest Territories, Canada, March 8-9, pp Thornthwaite C.W. (1948) An approach toward a rational classification of climate: Geographical Review, v. 38, p Tyhee NWT Corp (2011) Water Balance Climate and Hydrological Analysis. Wolock D.M. and McCabe G.J. (1999) Effects of potential climatic change on annual runoff in the conterminous United States: Journal of the American Water Resources Association, v. 35, p. 1,341 1, Yorkland Boulevard, Suite 800, Toronto, Ontario, M2J 4Y8 Phone (416) Fax (416)

43 Memo Re: Fiddler s Lagoon Monthly Water Budget February 3, 2012 /4 Appendix A. Modeling Results. Date PET Precip Soil AET Snow Runoff mm mm Moisture mm Storage mm Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun * Jul Aug Sep Oct Yorkland Boulevard, Suite 800, Toronto, Ontario, M2J 4Y8 Phone (416) Fax (416)

44 Memo Re: Fiddler s Lagoon Monthly Water Budget February 3, 2012 /5 Nov * Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Yorkland Boulevard, Suite 800, Toronto, Ontario, M2J 4Y8 Phone (416) Fax (416)

45 Memo Re: Fiddler s Lagoon Monthly Water Budget February 3, 2012 /6 Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec * estimated values 235 Yorkland Boulevard, Suite 800, Toronto, Ontario, M2J 4Y8 Phone (416) Fax (416)

46 APPENDIX C FIELD MEASUREMENT DATA

47 ph FID01 FID02 FID03 FID04 FID Jan Feb Apr-11 6-Jun Jul Sep-11 3-Nov-11 Date

48 Temperature ( C) FID01 FID02 FID03 FID04 FID Jan Feb Apr-11 6-Jun Jul Sep-11 3-Nov-11 Date

49 LDO (mg/l) 4 3 FID01 FID02 FID03 FID04 FID Jan Feb Apr-11 6-Jun Jul Sep-11 3-Nov-11 Date

50 Concentration (mg/l) FID01 FID02 FID03 FID04 FID Jan Feb Apr-11 6-Jun Jul Sep-11 3-Nov Dec Feb-12 1-Apr-12 Date

51 Concentration (mg/l) FID01 FID02 FID03 FID04 FID Jan Feb Apr-11 6-Jun Jul Sep-11 3-Nov Dec Feb-12 1-Apr-12 Date

52 APPENDIX D PHOSPHOROUS STUDY

53 Fiddler s Lake Treatment System Plan Final Report Sewage Effluent Characterization Phosphorous Study September 17 th, 2014 Public Works & Engineering City of Yellowknife Gary Strong Project Manager Submitted by Dillon Consulting Limited

54 TABLE OF CONTENTS 1 INTRODUCTION Wastewater Treatment Facility Description Current Effluent Limits METHODS Sampling Program Overview Schedule and Sample Collection INTERPRETATION AND DISCUSSION OF RESULTS Influent TP in the Lagoon TP in the Wetland TP in Effluent CONCLUSIONS TP loading at compliance point and Lake F1 sampling station Associated potential impacts of increased TP REFERENCES... 15

55 TABLES Table 1: CCME National Performance Standards... 2 Table 2: Water Licence Effluent Quality Requirements... 3 Table 3: Effluent Discharge Objectives for Ammonia and Phosphorus... 3 Table 4: Influent Contaminant Loadings... 5 Table 5: Average Concentrations for FID01 to FID05 from June 7, 2011 to October 13, Table 6: Average Concentrations for Supernatant for Parameters of Concern at Lake F Table 7: Average Concentrations for Supernatant for Parameters of Concern at Lake F Table 8: Average Concentrations for Supernatant for Parameters of Concern at Lake F Table 9: Average, 95th Percentile, Minimum, and Maximum Concentrations for Parameters of Concern for Lake F3 Compliance Point (0032-F3)... 9 Table 10: Average, 95th Percentile, Minimum and Maximum Concentrations for Parameters of Concern for Lake F1 (0032-F1) FIGURES Figure 1: Overview of Fiddler s Lake Treatment System... 2 Figure 2: Trends in TP Concentrations for Main Lagoon Cell: FID01 to FID Figure 3: Trends in TP Concentration at Lake F3 Compliance Point (0032-F3) Figure 4: Trends in TP Concentrations at Lake F1 (0032-F1)... 12

56 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study Executive Summary EXECUTIVE SUMMARY Dillon Consulting Limited (Dillon) was retained by the City of Yellowknife (City) to complete a yearlong sampling program to assist with the characterization of the effluent in the Fiddler s Lake Lagoon system as per the D.20 of the water licence. This report presents part of a larger study on the characterization of the effluent quality at the Fiddler s Lake Lagoon system. Results of the sampling program with regard to phosphorus are discussed, including a summary and a comparison of the current effluent quality in accordance with the Canadian Council of Ministers of the Environment (CCME) Canada-Wide Strategy for the Management of Municipal Wastewater Effluent (MWWE) as per D.20 of the water licence. Fiddler s Lake Treatment System is currently meeting all guideline limits for all parameters of concern with the exception of total phosphorus, as stated in the water licence and National Performance Standards (NPSs) for total suspended solids (TSS) and biological oxygen demand (CBOD 5 ) as stated in the CCME Canada-Wide Strategy for the Management MWWE. There are potential opportunities to reduce the total phosphorus mass loading within the main lagoon holding cell, which will further lead to the reduction of total phosphorus to the wetlands. Treatment options for the reduction of total phosphorus include chemical precipitation through the use of alum or ferric nitrate. Dillon Consulting Limited September 2014 i Project

57 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study 1 INTRODUCTION The objective of this study was to characterize the wastewater effluent of Fiddler s Lake Treatment System in accordance with the Canadian Council of Ministers of the Environment (CCME) Canada-Wide Strategy for the Management of Municipal Wastewater Effluent (MWWE) following a yearlong sampling program. In addition to the characterization of the effluent quality, the influent was characterized in terms of typical influent for piped services. The yearlong sampling program was established to collect analytical data for a number of parameters, including total phosphorus (TP) that would assist with the characterization process. The wastewater effluent quality was compared to water licence effluent limits, the National Performance Standards (CCME, Management of MWWE) and Canadian Water Quality Guidelines (CWQG) for Freshwater Aquatic Life (FAL). Influent quality data was also monitored and compared to literature values typical for the type of wastewater. This summary report will provide a brief description of the methodology and rationale for the sampling program, the assessment of the sample program results for TP, and the characterization of the TP concentration in the effluent in accordance to the CCME Management of MWWE guideline limits and effluent limits stated in the water licence. 1.1 Wastewater Treatment Facility Description The wastewater treatment facility employs a natural holding lagoon and wetland system, known collectively as Fiddler s Lake. The lagoon is situated off Highway 3, approximately 6 km west from the Yellowknife airport. The lagoon consists of three main ponds, labeled F8, F7 and F6 (east to west), which act as a holding and pre-treatment area for the wastewater prior to decanting into the wetland area, consisting of natural lakes containing various types of vegetation, organic and sandy material, until the ultimate discharge to Great Slave Lake. Flow channels between the natural lakes allow for natural filtration through the wetlands from east to west. The wastewater lagoon functions as a facultative lagoon, allowing both aerobic and anaerobic digestion to take place. Three berms were installed at various points along the lagoon to provide additional capacity by increasing the depth and combining ponds F8, F7, and F6. With the addition of these three berms, the level increased to the current depth of approximately 4.5 m to 5.0 m. A trench was built at the southeast end of Trapper s Lake, which would divert runoff water to the so-called Unnamed Lake, further draining into the Kam Lake Drainage system. Dillon Consulting Limited September Project

58 The contents of the main holding lagoon cell are seasonally discharged through the wetland area once a year, typically starting between mid- to late September. Discharge into the wetland is controlled through a weir at the west end of main holding lagoon (Lake F6 at control point ). The weir is a stop log structure and a drain pipe with discharge valve. Decanting usually lasts until mid-november to early December depending on the start of the decant. The treated water travels approximately 13 km through the wetland lakes F5, F4, and F3. The compliance point is at the downstream end of wetland Lake F3. The ultimate receiver is Great Slave Lake which is separated from Lake F3 by a series of additional wetland lakes. 1.2 Current Effluent Limits Figure 1: Overview of Fiddler s Lake Treatment System The CCME strategy requires that all facilities achieve the National Performance Standards for effluent quality and develop and manage site-specific effluent discharge objectives (EDOs). In particular, the NPSs address pollutants common to most wastewater discharges such as BOD 5 and TSS. These NPSs are listed in Table 1 below, and represent the minimum effluent quality requirements for all wastewater systems that discharge to surface water. Table 1: CCME National Performance Standards Parameter Concentration (mg/l) Total Suspended Solids, TSS 25 5-day CBOD 5 25 Total Chlorine Residual, TRC September 2014 Dillon Consulting Limited Project

59 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study Accordingly, Part D of the City s current water licence issued by the Mackenzie Land and Water Board on June 2, 2010 sets forth conditions applying to waste disposal with which the Fiddler s Lake Treatment System must comply. These conditions include specific wastewater effluent limits and effluent discharge objectives (EDOs) at the compliance point (labeled 0032-F3) located at the outlet of Lake F3. The current effluent quality requirements as stated in Part D.2 of the water licence are listed in Table 2 below. The EDO outlined in the water licence (Schedule 2, item 3b) for phosphorus is listed in Table 3. Table 2: Water Licence Effluent Quality Requirements Parameter (units) Maximum Average Concentration (a) Maximum Grab Sample Fecal Coliform (FC per 100 ml) day Biochemical Oxygen Demand, BOD 5 (b) (mg/l) Total Suspended Solids, TSS (mg/l) ph (ph units) 6 to 9 6 to 9 Oil and Grease Acute Toxicity Notes: No visible sheen Static pass/fail bioassay test for Rainbow Trout and Daphnia Magna whereby 70% survival is considered a pass. (a) Average concentration is the discrete average of four (4) consecutive analytical results, or if less than four analytical results, the discrete average of the analytical results collected during a batch decant. (b) The CCME Strategy uses carbonaceous biochemical oxygen demand (CBOD 5 ) as an effluent parameter rather than the traditional total BOD 5 due to concerns surrounding the effect of nitrogenous oxygen demand included in the BOD 5 measurement. Table 3: Effluent Discharge Objectives for Ammonia and Phosphorus Parameter (units) Average Concentration (a) Maximum Concentration Total Ammonia as Nitrogen, NH 3 -N (mg/l) 5 10 Total Phosphorus, TP (mg/l) Notes: (a) Average concentration is the discrete average of four (4) consecutive analytical results.or if less than four analytical results, the discrete average of the analytical results collected during a batch decant. It is important to note that the CCME guidelines for discharge objectives represent values to be attained over time, rather than static regulatory limits. Dillon Consulting Limited September Project

60 2 METHODS 2.1 Sampling Program Overview An extensive sampling program was organized to study and understand the level of treatment at each stage of the treatment process along the wastewater s discharge pathway to the final receiving water body. The initial characterization of the effluent consisted of sampling the following locations along the wastewater discharge pathway: Raw sewage/influent at Lift Station No. 5; Fiddler s Lake main holding cell at five locations: FID01 through FID05; Decant structure prior to the discharge weir; Outlet of wetland Lake F5; Middle of wetland Lake F4; Middle of wetland Lake F3; Compliance Point/Outlet of wetland Lake F3; and Middle of wetland Lake F1. Samples were analyzed by Taiga Environmental Laboratories in Yellowknife, NT for all parameter analysis with the exception of TSS, VSS and TKN, which were analyzed by Exova in Edmonton, AB Schedule and Sample Collection Sample collection for the characterization of the wastewater effluent was typically completed on a two week cycle from early June 2011 to early November In some cases, sampling locations along the wastewater discharge pathway were sampled weekly to meet the sampling requirements as stated in the water licence. The weekly sampling was only completed during the decant period. Raw wastewater samples were collected at Lift Station No. 5 a total of 12 times, once in February 2011 and 11 times from early June to early November Three samples were collected during the winter months over the year, in February 2011, January 2012, and February Sludge samples were taken at all locations, with the exception of the FID01, Lake F3 at Compliance Point (0032-F3) and Lake F1 (0032-F1) sampling locations. All wastewater and sludge samples were sent to Taiga Environmental Laboratory for analysis within 24 hours of the sampling time. The full results from the wastewater sampling analysis and historical operating data provided by the City of Yellowknife can be seen in the original report, Fiddler s Lake Treatment System Studies and Management Plan: Sewage Effluent Characterization by Dillon Consulting Limited. 4 September 2014 Dillon Consulting Limited Project

61 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study 3 INTERPRETATION AND DISCUSSION OF RESULTS 3.1 Influent A profile of the contaminant average concentrations of the influent were generated and compared to standard literature values for raw wastewater (Metcalf & Eddy, 4 th ed, 2003). The influent unit loading was based on the average grab sample concentrations and the total flow rate measurements of Lift Station No. 5 and No. 6. The unit loadings were based on a population of 20,248 for the year 2011 (Northwest Territories Bureau of Statistics, 2011), which included the population for the populated areas outside of the city limits that are serviced by truck. Table 4 provides the influent loadings for the wastewater leaving the LS No. 5. Parameter Table 4: Influent Contaminant Loadings Average (a) Measured Grab Sample Conc. (mg/l) Average (b) Mass Load (kg/d) Average (b) Unit Loading (g/cap d) Typical Unit Loading (c) (g/cap d) TSS 291 2, BOD , COD 431 3, NH 3 -N TKN TP Soluble Orthophosphate as P NA (d) Notes: (a) Average concentrations were calculated based on 12 samples collected from Lift Station No. 5, once in February 2011 and 11 times between early June and early November (b) Average mass loads and unit loadings were based on the daily measured parameter concentration and influent flow rate. (c) Obtained from Metcalf & Eddy, 4 th ed, (d) Not reported in Metcalf & Eddy, 4 th ed., With the exception of total phosphorus, the calculated unit loadings for the parameters of concern were within the typical ranges for piped raw wastewater. The ammonia as N unit loading was observed near the higher end of the typical range. The TP unit loading was slightly lower than the typical range, with unit loading rate of 2.31 g/capita d. 3.2 TP in the Lagoon Samples from the main holding cell were collected every two weeks during the open water season. Table 5 provides the average concentrations for the parameters of concern during that time period. Dillon Consulting Limited September Project

62 Table 5: Average Concentrations for FID01 to FID05 from June 7, 2011 to October 13, 2011 Parameter (units) FID01 FID02 FID03 FID04 FID05 ph, Lab (ph units) ph, Field (ph units) TSS (mg/l) BOD 5 (mg/l) NH 3 -N (mg/l) TKN (mg/l) NO 3 + NO 2 N (mg/l) TP (mg/l) Chlorophyll-A There were fluctuations in all of the parameter concentrations from the five sampling stations within the main lagoon holding cell for the open water season as noted in the table above. Figure 2 illustrates the trends in the TP concentrations for the five sampling locations along the main lagoon holding cell. The dashed vertical lines represent the decant period. Figure 2: Trends in TP Concentrations for Main Lagoon Cell: FID01 to FID05 For all sampling locations along the main lagoon cell, the highest TP concentration was observed in early September at the FID05 sampling location and the lowest TP concentration was observed in late July at 6 September 2014 Dillon Consulting Limited Project

63 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study the FID01 sampling location. The average TP concentrations remained relatively constant from the lagoon inlet (FID01) to the lagoon outlet (FID05). 3.3 TP in the Wetland The average concentration of TP in the supernatant for Lake F5, Lake F4 and Lake F3 for the decant period and full year is shown along with other parameters of concern in Table 6 to Table 8 on the subsequent pages. Table 6: Average Concentrations for Supernatant for Parameters of Concern at Lake F5 Parameter (units) Year (a) Decant Period (b) Average 95 th Percentile Min Max Average 95 th Percentile Min Max Lab ph (ph units) Field ph (ph units) TSS (mg/l) CBOD 5 (mg/l) BOD 5 (mg/l) NH 3 -N (mg/l) TKN (mg/l) NO 3 + NO 2 N (mg/l) TP (mg/l) Notes: (a) The yearly averages were calculated based on the values from February 16, 2011 to February 15, This is based on twelve samples. (b) Decant period was from September 6 to December 2, The averages calculated for the decant period were based on the values taken from September 14 to November 30, This is based on three samples. Dillon Consulting Limited September Project

64 Table 7: Average Concentrations for Supernatant for Parameters of Concern at Lake F4 Parameter (units) Year (a) Decant Period (b) Average Min Max Sept 26, 2011 Lab ph (ph units) Field ph (ph units) TSS (mg/l) CBOD 5 (mg/l) BOD 5 (mg/l) NH 3 -N (mg/l) TKN (mg/l) NO 3 + NO 2 N (mg/l) TP (mg/l) Notes: (a) The yearly averages were calculated based on the values from February 16, 2011 to February 15, This is based on four samples. (b) Decant period was from September 6 to December 2, The averages calculated for the decant period were based on the values taken from September 14 to November 30, 2011, which equates to one sample. Table 8: Average Concentrations for Supernatant for Parameters of Concern at Lake F3 Parameter (units) Year (a) Decant Period (a) Average 95 th Percentile Min Max Average 95 th Percentile Min Max ph. Lab (ph units) ph, Field (ph units) TSS (mg/l) CBOD 5 (mg/l) BOD 5 (mg/l) NH 3 -N (mg/l) TKN (mg/l) NO 3 + NO 2 N (mg/l) TP (mg/l) Chloropyll-a Notes: (a) The yearly averages were calculated based on the values from February 16, 2011 to February 15, (b) Decant period was from September 6 to December 2, The averages calculated for the decant period were based on the values taken from September 14 to November 30, September 2014 Dillon Consulting Limited Project

65 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study 3.4 TP in Effluent With the exception of TP, all parameters of concern for wastewater treatment were below the specified limits at both the Lake F3 compliance point (0032-F3) and the Lake F1 (0032-F1) station, as stated in the water licence as well as CCME MWWE NPS guidelines (Table 9 and Table 10, respectively). Note that exceedances have been bolded and highlighted red. For the decant period, only the TP concentration exceeded the water licence discharge objective. The TP concentration for the decant period was approximately double that of the specified maximum average EDO concentration, and the annual concentration of TP was also above the water licence EDO. Table 9: Average, 95th Percentile, Minimum, and Maximum Concentrations for Parameters of Concern for Lake F3 Compliance Point (0032-F3) Parameter (units) Year (a) Decant (b) Water Average 95 th Min Max Average 95 th Min Max Licence (c) Percentile Percentile Lab ph (ph units) Field ph (ph units) CCME Guideline Limit TSS (mg/l) (d) CBOD 5 (mg/l) (d) BOD 5 (mg/l) COD (mg/l) NH 3 -N (mg/l) (e) TKN (mg/l) NO 3 + NO 2 N (mg/l) TP (mg/l) DP (mg/l) FC (CFU/100 ml) Notes: (a) The yearly averages were calculated based on the values from February 16th, 2011 to February 15th, (b) Decant period was from September 6 th to December 2 nd, The averages calculated for the decant period were based on the values taken from September 14 th to November 30 th, (c) Maximum average concentration. (d) CCME Management of MWWE, National Performance Standards. (e) CCME Water Quality Guidelines for the Protection of Freshwater Aquatic Life. Dillon Consulting Limited September Project

66 Table 10 lists the average, minimum and maximum concentrations for the parameters of concern for Lake F1 (0032-F1) station for the decant period and complete year. Table 10: Average, 95th Percentile, Minimum and Maximum Concentrations for Parameters of Concern for Lake F1 (0032-F1) Parameter (units) Year (a) Decant Period (b) Water Average 95 th Min Max Average 95 th Min Max Licence (c) Percentile Percentile CCME Guideline Lab ph (ph units) Field ph (ph units) TSS (mg/l) (d) CBOD 5 (mg/l) (d) BOD 5 (mg/l) COD (mg/l) NH 3 N (mg/l) (e) TKN (mg/l) NO 3 N + NO 2 N (mg/l) TP (mg/l) DP (mg/l) FC (CFU/100 ml) Notes: (a) The yearly averages were calculated based on the values from February 16th, 2011 to February 15th, (b) Decant period was from September 6 th to December 2 nd, The averages calculated for the decant period were based on the values taken from September 14 th to November 30 th, (c) Maximum average concentration. (d) CCME Management of MWWE, National Performance Standards. (e) CCME Water Quality Guidelines for the Protection of Freshwater Aquatic Life. 10 September 2014 Dillon Consulting Limited Project

67 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study TP concentration at the compliance point (0032-F3) station exceeded the water licence maximum grab concentration 50% of the time, generally in the winter and fall (Figure 3), whereas the 0032-F1 station only exceeded the water licence maximum grab concentration limit 10% during the year. Both sampling locations did not meet the water licence maximum average concentration of 1.0 mg/l. TP concentrations were generally the lowest between the months of June and August, when natural treatment conditions (such as plant uptake) were optimal. Figure 3: Trends in TP Concentration at Lake F3 Compliance Point (0032-F3) Dillon Consulting Limited September Project

68 Figure 4 illustrates the trends in the TP concentrations for the Lake F1 sampling location (0032-F1). The TP concentration exceeded the water licence maximum grab sample concentration of 2 mg/l twice over the sampling period. The exceedances occurred in early April, prior to the spring breakup and again in early February, under ice conditions. The TP running average concentrations were all below the maximum grab sample concentration for the entire sampling period but above the water licence maximum average concentration for the most of the year, with the exception of the period between early June and early September. Figure 4: Trends in TP Concentrations at Lake F1 (0032-F1) 12 September 2014 Dillon Consulting Limited Project

69 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study 4 CONCLUSIONS 4.1 TP loading at compliance point and Lake F1 sampling station Based on the Environmental Risk-Based Approach flow diagram, the effluent quality from Fiddler s Lake Lagoon meets the National Performance Standards but it does not meet the EDOs as set out in the water licence issued by the Mackenzie Valley Land and Water Board. With the exception of total phosphorus, the moving average concentrations at the Lake F3 compliance point (0032-F3) sampling location were all below the water licence effluent limits and the NPS limits. The total phosphorus moving average concentrations at the Lake F3 compliance point (0032-F3) sampling station exceeded the maximum average concentration of 1.0 mg/l approximately 96% throughout the sampling period and exceeded the maximum grab concentration of 2.0 mg/l approximately 54% over the sampling period. Annual percent removal of the parameters of concern from the raw influent to the decant structure of the main lagoon cell, to Lake F3 at the compliance point (0032-F3) sampling station and to Lake F1 (0032- F1) sampling station are listed in Table 5 below. Notes: Table 5: Annual Average Percent Removal for Parameters of Concern Parameter Year Open Water (a) From Raw to Decant Structure of Main Lagoon Cell From Raw to Lake F3 at Compliance Point (0032- F3) From Raw to Lake F1 (0032-F1) From Raw to Decant Structure of Main Lagoon Cell From Raw to Lake F3 at Compliance Point (0032- F3) From Raw to Lake F1 (0032-F1) TSS BOD NH 3 -N TP (a) Sampling data from June 1, 2011 to October 13, The majority of TP was removed in the wetlands but some minor removal of TP in occurred in the main lagoon cell. Similar to the TSS and BOD 5 removal rates, there was very little variance between the open water season removal percentages versus the annual average removal percentages. There may be opportunities for reduction at the source or within the wastewater treatment process to reduce the TP concentrations below the water licence limits. The Fiddler s Lake Treatment System, specifically the wetland, may work as a sponge accumulating sediment with phosphorus in addition to algae and aquatic vegetation growth which takes up TP. Once the sediment is mobilized (i.e. during discharge period or when vegetation and algae decay) which usually occurs in September through November, phosphorus could be released. If the total phosphorus load to the treatment system could be reduced through the use of chemical precipitation, the TP loading to the wetland could also be reduced, which may result in a low enough concentration despite that the above uptake/release process would still Dillon Consulting Limited September Project

70 take place. It may take time to flush out some of the TP that was stored in the lagoon and wetland lakes before significant changes could be observed. The other option would be to treat the effluent flow at the outfall to the wetland. Based on the high flows and location, the flushing of precipitate into wetland would likely not be feasible. 4.2 Associated potential impacts of increased TP Generally the Arctic is a nutrient limited environment (Chapin and Bledsoe, 1992; Nadelhoffer et al., 1992; Gordon et al., 2001) and in particular many aquatic systems are oligotrophic as a result of the limited natural nutrient and organic inputs. The Fiddler's Lake Sewage Lagoon and wetland system processes large quantities of anthropogenic nutrient and organic inputs. The main processes responsible for nutrient cycling within the wetland treatment system are complex and not fully understood, but include nitrification, methanogenesis and anaerobic mineralisation of organic material by sulphur bacteria. In temperate climates these biochemical processes can occur year round with only relatively small fluctuations in seasonal metabolic activity. Within the Arctic the main constrainsts on this metabolic activity and asscociated microbial decomposition, include: large seasonal variation in temperature, long periods of ice cover and availability of sunlight for photosynthetic activity. The ecological effects of eutrophication in the Arctic remain uncertain, but there is concern that enhanced nitrogen and phosphorus enrichment in particular could force ecological change in otherwise oligotrophic nitrogen and phosphorus -limited ecosystems (Chapin and Bledsoe, 1992; Nadelhoffer et al., 1992). The most pronounced impacts of eutrophication have been seen closer to populated regions where there have been many documented examples of environmental damage due to eutrophication (Jónsdóttir et al., 1995; Woodin, 1997; Gordon et al., 2001). Increases in nitrogen and phosphorus inputs in the Arctic may be particularly critical because there may be changes in species composition and biodiversity over time (Walker et al., 2001). 14 September 2014 Dillon Consulting Limited Project

71 Fiddler s Lake Treatment System Plan Sewage Effluent Characterization Phosphorous Study 5 REFERENCES Metcalf and Eddy Wastewater Engineering: Treatment and Reuse, 4 th ed. McGraw Hill, Toronto, ON. Canadian Council of Ministers of the Environment (CCME) Canada-wide Strategy for the Management of Municipal Wastewater Effluent. February 17, 2009, Whitehorse. CCME. Technical Supplement 1. Canada-wide Strategy for the Management of Municipal Wastewater Effluent. Environmental Risk Management: Framework and Guidance. April CCME. Technical Supplement 2. Canada-wide Strategy for the Management of Municipal Wastewater Effluent. Environmental Risk Management: Framework and Guidance. June CCME. Technical Supplement 3. Canada-wide Strategy for the Management of Municipal Wastewater Effluent. Environmental Risk Management: Framework and Guidance. June Dillon Consulting Limited. May ph Compliance Point Assessment. Final Report. Dillon Consulting Limited Expansion of Fiddler s Lagoon Treatment System. Final Report. Dillon Consulting Limited Synopsis of Muncipal Wastewater Treatment and Discharge in the NWT. Final Report. Dillon Consulting Limited Fiddler s Lake Lagoon Treatment System Studies and Management Plan: Sewage Effluent Characterization. Final Report. Heinke, G.W., Smith, D.W., Finch, G.R Guidelines for the planning and design of wastewater lagoon systems in cold climates. Canadian Journal of Civil Engineering Volume 18: NWT Water Board Guidelines for the Discharge of Treated Municipal Wastewater in the Northwest Territories. Dillon Consulting Limited September Project

72 APPENDIX E BOD 5 CBOD 5 STUDY

73 MEMO TO: City of Yellowknife cc: FROM: DATE: July 14, 2014 SUBJECT: OUR FILE: Fiddler s Lake Treatment System BOD 5 /CBOD 5 This memo summarizes the results of a three-year study on the characterization of wastewater effluent quality, specifically for carbonaceous biological oxygen demand (CBOD). The summary is in response to item D.21 in the City water licence, as follows: D. 21 The Licensee shall complete monitoring of wastewater effluent quality for carbonaceous biological oxygen demand (CBOD) and biological oxygen demand (BOD) for a minimum of three years. The study findings, including a trend analysis, shall be submitted to the Board for approval August 31, Currently, the Fiddler s Lake Treatment System is meeting all guideline limits and National Performance Standards (NPSs) for all parameters of concern including biological oxygen demand (CBOD 5 ) (with the exception of total phosphorus), as stated in the water licence and the CCME Canada-Wide Strategy for the Management MWWE, respectively. The water licence maximum average and maximum grab sample effluent quality requirements are outlined in Table 1, with values for BOD 5 highlighted in bold, and the CCME National Performance Standards are shown in Table 2.

74 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 2 Table 1: Water Licence Effluent Quality Requirements Parameter (units) Maximum Average Concentration (a) Maximum Grab Sample Fecal Coliform (FC per 100 ml) day Biochemical Oxygen Demand, BOD 5 (mg/l) Total Suspended Solids, TSS (mg/l) Total Ammonia as Nitrogen, NH 3 -N (mg/l) 5 10 Total Phosphorus, TP (mg/l) ph (ph units) 6 to 9 6 to 9 Oil and Grease Acute Toxicity No visible sheen Static pass/fail bioassay test for Rainbow Trout and Daphnia Magna whereby 70% survival is considered a pass. Notes: (a) Average concentration is the discrete average of four (4) consecutive analytical results.or if less than four analytical results, the discrete average of the analytical results collected during a batch decant. Table 2: CCME National Performance Standards Parameter Concentration (mg/l) Total Suspended Solids, TSS 25 5-day CBOD 5 25 Total Chlorine Residual, TRC 0.02 It should be noted that the CCME MWWE guideline limits for CBOD 5 is slightly less stringent than those stated in the water licence for the facilty. However, the water licence requires the measurement of BOD 5 rather than the more sensitive CBOD 5 measurement required by the CCME MWWE guideline document. The Strategy uses carbonaceous biochemical oxygen demand (CBOD 5 ) as an effluent parameter rather than the traditional total BOD 5 because of concerns about the effect of nitrogenous oxygen demand. As the duration of the Fiddler s Lake main holding lagoon cell discharge was greater than one month, samples were collected every two weeks. The compliance with the NPS CBOD 5 limit was based on the annual average of the biweekly results obtained during the discharge period. Table 3 shows a list of the sampling stations for supernatant where BOD 5 /CBOD 5 was analyzed along the wastewater discharge pathway. All wastewater samples were sent to Taiga Environmental Laboratory for analysis within 24 hours of the sampling time.

75 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 3 Table 3: BOD 5 /CBOD 5 Analysis Sampling Stations Parameter Supernatant Sludge Raw FID01 FID05 FID01-05 Middle FID01-05 Bottom Decant Lake F5 Lake F4 Lake F3 - Middle Lake F3 (0032-F3) Lake F1 (0032-F1) FID01 FID05 Lake F5 Lake F4 Lake F3 - Middle BOD 5 CBOD 5 sbod5 The full and detailed results of the wastewater sampling analysis and historical operating data provided by the City of Yellowknife can be found in the Effluent Characterization Report by Dillon Consulting Limited (2014). BOD 5 in Influent A profile of the contaminant average concentrations of the influent was generated and compared to standard literature values for raw wastewater (Metcalf & Eddy, 4 th ed, 2003). It was determined that the average mass load for the 2011 study period was 1,836 kg/d of BOD 5, resulting in an average unit loading of 91 g/cap d (based on a population of 20,248 for the year 2011, Northwest Territories Bureau of Statistics, 2011). This value is in agreement with reported literature values, with typical unit loading ranging from g/cap d for similar sized wastewater systems. BOD 5 in the Lagoon Samples from the main holding cell were collected every two weeks during the open water season from five sampling stations down the holding cell. The average concentrations for BOD 5 during that time period are shown in Table 4. Table 4: Average BOD 5 Concentrations for FID01 to FID05 from June 7, 2011 to October 13, 2011 Parameter (units) FID01 FID02 FID03 FID04 FID05 BOD 5 (mg/l) BOD 5 concentrations for all sampling locations within the main holding cell over the sampling season are shown in Figure 1. The dashed vertical lines represent the decant period. Seasonal variations are noted, with the highest values recorded in February, and lowest values recorded mid-summer and in mid-september.

76 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 4 Figure 1: Trends in BOD5 Concentrations for Main Lagoon Cell: FID01 to FID05 BOD 5 /CBOD 5 in Wetland The average BOD 5 concentrations in the supernatant were measured for Lake F5, Lake F4 and Lake F3 for the decant period and full year. Observations are listed in Table 5. Sampling point Table 5: Average BOD 5 /CBOD 5 Concentration for Supernatant at Lakes F5, F4 and F3 Parameter (units) Year (a) Decant Period (b) Average Min Max Sept 26, 2011 Lake F5 Lake F4 Lake F3 CBOD 5 (mg/l) BOD 5 (mg/l) CBOD 5 (mg/l) BOD 5 (mg/l) CBOD 5 (mg/l) BOD 5 (mg/l) Notes: (a) The yearly averages were calculated based on the values from February 16, 2011 to February 15, This is based on four samples.

77 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 5 (b) Decant period was from September 6 to December 2, The averages calculated for the decant period were based on the values taken from September 14 to November 30, 2011, which equates to one sample. BOD 5 /CBOD 5 at Compliance Point at Lake F3 and Lake F1 station The quality of the effluent at Lake F3 at compliance point (0032-F3) and Lake F1 (0032-F1) stations were relatively similar in terms of average concentrations and grab sample concentrations over the observed sampling period. However, there were periods the BOD 5 /CBOD 5 was higher at one sampling station than the other. This is likely due to higher than normal visible solids and organic material in the water body at the time of sampling. The higher than normal visible solids were from the natural occurring plants within the wetland lakes. However, at the compliance point, the BOD 5 /CBOD 5 parameter for wastewater treatment was consistently below the specified limits as stated in the water licence as well as CCME MWWE guideline for both the decant and holding periods, as shown in Table 6. Table 6: Average, 95th Percentile, Minimum, and Maximum Concentrations for BOD 5 /CBOD 5 at Lake F3 Compliance Point (0032-F3) Parameter (units) Year (a) Decant (b) Water Average 95 th Min Max Average 95 th Min Max Licence (c) Percentile Percentile CCME Guideline Limit CBOD 5 (mg/l) (d) BOD 5 (mg/l) Notes: (a) The yearly averages were calculated based on the values from February 16th, 2011 to February 15th, (b) Decant period was from September 6 th to December 2 nd, The averages calculated for the decant period were based on the values taken from September 14 th to November 30 th, (c) Maximum average concentration. (d) CCME Management of MWWE, National Performance Standards. (e) CCME Water Quality Guidelines for the Protection of Freshwater Aquatic Life. Additionally, all BOD 5 concentrations for the 0032-F3 and 0032-F1 stations, as illustrated in Figure 2 and Figure 3, were below the water licence maximum grab sample concentration of 30 mg/l.

78 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 6 Figure 2: Trends in BOD5 Concentrations at Lake F3 Compliance Point (0032-F3)

79 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 7 Figure 3: Trends in BOD5 Concentrations at Lake F1 (0032-F1) Similarly to BOD 5, CBOD 5 concentrations for both stations were well below the CCME MWWE NPS limit of 25 mg/l, ranging from below laboratory detection limits up to 18 mg/l as illustrated in Figure 4 and Figure 5. The correlation between TSS and BOD 5 concentrations (TSS:BOD 5 ) was not stable over the entire sampling period. Therefore, the observed higher BOD 5 concentrations were not the result of washout of the organic solids.

80 MEMO TO: City of Yellowknife DATE: July 14, 2014 Page 8 Figure 4: Trends in CBOD5 Concentration at Lake F3 Compliance Point (0032-F3)