Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant

Transcription

1 JLR No.: Revision: 0 April 16, 2018 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Final Version Value through service and commitment

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3 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Table of Contents INTRODUCTION... 1 BACKGROUND INFORMATION... 1 FUTURE CAPACITY OF WWTP Introduction Review of the WWTP Historic Flows Population Growth Proposed Future Capacity of the WWTP Timing of the Upgrades Definition of Plant Upgrades... 9 CLIMATE CHANGE ANALYSIS Introduction Predicted Changes in Precipitation Predicted Changes in Temperature Predicted Changes in Wind/Storms...14 DISCUSSION OF POTENTIAL IMPACTS TO THE WWTP Potential Impacts from Changing Precipitation Potential Impacts from Changing Temperatures Potential Impacts from Changing Winds/Storm Events...21 POTENTIAL RESILIENCEY PLANNING MEASURES Discussion of Findings Potential Resiliency Planning Measures...22 CONCLUSION/RECOMMENDATIONS...23 List of Figures Figure 1: WWTP Flows (m 3 /d) 1998 to Figure 2: WWTP Daily Flows for Period between 2012 and Figure 3: Historic WWTP Flows and Predicted Growth between 2008 and Figure 4: Precipitation for Year 2016 (mm)...13 Figure 5: Precipitation for Year 2017 (mm)...13 Figure 6: Minimum and Maximum Flows in the Mississippi River (1922 to 2017)...15 Figure 7: Daily Flows in the Mississippi River (2012 to 2016)...16 Figure 8: Predicted River Flows in m 3 /s Dry Weather (2011 to 2099)...16 Figure 9: Predicted River Flows in m 3 /s Average Weather (2011 to 2099)...17 Figure 10: Predicted River Flows in m 3 /s Wet Weather (2011 to 2099)...17 Figure 11: WWTP Flow versus River Flow Year Figure 12: WWTP Flow versus River Flow Year Figure 13: WWTP Flow versus River Flow Year Figure 14: Raw Influent Flow versus Precipitation Year Figure 15: Raw Influent Flow versus Precipitation Year JLR No.: i- Revision: 0

4 Resiliency Plan Wastewater Treatment Plant Final Version List of Tables Table 1: Average and Maximum Flows at the WWTP from Year 2008 to Table 2: 5 and 10 Year Averages for the Average and Maximum Day Flows... 5 Table 3: Average Unit Flows per Day per Household for Various Periods... 5 Table 4: Proposed Capacities for All Major Processes... 6 Table 5: Plant Expansion Phasing... 9 Table 6: Proposed Plant Upgrades for Capacity Expansion... 9 Table 7: Treated Effluent Limits...11 Table 8: Precipitation Change Predictions...12 Table 9: Temperature and Precipitation Change Predictions...14 Table 10: Climate Change Effects, Potential Impacts and Possible Resiliency Measures...22 JLR No.: ii- Revision: 0

5 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant INTRODUCTION The Town of Carleton Place (the Town) has identified a need to develop a Resiliency Plan for both their Wastewater Treatment Plant (WWTP) and Water Treatment Plant (WTP) based on previous observations of climatic related events. These events included a very wet 2017 spring season that stressed the WWTP and a very dry season in the summer of 2016 that stressed the WTP. J.L. Richards & Associates Limited (JLR) were retained by the Town in January 2018 to assist in undertaking a review of both of these facilities in order to assess their vulnerability to current and future projected climatic conditions and to identify measures that could be considered to ensure both facilities have sufficient resiliency to accommodate these conditions. This Report focuses specifically on the WWTP and a separate report has been prepared for the WTP. The objectives of this Report are as follows: Present a rationale for the projection of flows that the WWTP will need to accommodate in the future strictly based on the continued growth of the community and identify upgrades required to accommodate this growth; Present and analyze climatic and plant related data in order to assess potential future impacts to performance of the plant as a result of climate change; Identify possible resiliency measures and implementation timeframes that the Town could consider to mitigate the potential impacts due to climate change (i.e. separate from those required strictly for future capacity expansion due to growth). BACKGROUND INFORMATION Climate change has become a reality with impacts experienced across the globe and locally. Temperatures are warming everywhere causing hotter, drier periods of drought and water shortages. This is also creating conditions for more severe and frequent storm events leading to flooding. The Ontario Ministry in charge of managing and protecting our environment has fully recognized this reality as was made very evident by changing their organizational name in June 2014 to the Ministry of Environment and Climate Change (MOECC). New climate change related initiatives, including formal legislation, guidance documents and manuals and action plans have been developed within Ontario and Canada in recent years with the overarching goal of ensuring long-term sustainability of our way of life through protection of both the natural and manmade environments. A part of these initiatives includes reviewing existing manmade infrastructure (e.g. transportation, energy supplies, water supplies, etc.), assessing vulnerabilities, and then developing Resiliency Plans to ensure robustness, redundancy and to mitigate impacts from changing climatic conditions that will result in more reliable and uninterrupted services as well as long term economic benefits. As noted in Climate Ready - Ontario s Adaptation Strategy and Action Plan (2011 to 2014), Well targeted, early planning and meaningful investment to JLR No.: Revision: 0

6 Resiliency Plan Wastewater Treatment Plant Final Version improve the Province s climate resilience are likely to be more effective than complex disaster relief efforts after the event. Initiatives such as the Water Conservation Act (and Municipal Water Sustainability Plan), Clean Water Act, Source Water Protection, Ontario s Five Year Climate Change Action Plan ( ) and Optimization Guidance Manual for Sewage Works have all been undertaken with some of their focus (if not all) on the long term resiliency of water supply and wastewater management systems. The Town of Carleton Place owns, operates and maintains various assets that provide services to residents including a communal water supply system and a communal wastewater management system. In recent years, impacts to these facilities from both water shortages and flooding events have occurred. In the particular case of the WWTP, sustained rainfall in the spring of 2017 caused flooding throughout the area and resulted in two separate spring peak flow events at the WWTP. Inflow and infiltration into the sanitary sewer system caused sustained high flows at the WWTP putting pressure on the plant's ability to adequately treat all flows. Recognizing the importance of the WWTP to the community, the Town is taking this first planning step to ensure it will be able to perform under predicted conditions. This includes the identification of resiliency measures that may be required in the future to reduce overall vulnerability and ensure that the plant can continue to provide long term and sustainable performance. FUTURE CAPACITY OF WWTP 3.1 Introduction To assess potential impacts from climate change, it was first necessary to determine what the future requirements of the plant are in terms of additional treatment capacity due to future growth. Growth will result in the generation of more flows to the plant and this could compound climate change impacts. In some cases it could also be determined that the additional infrastructure needed to address growth may also assist in addressing resiliency. For example, expanding the capacity of the plant would include the ability to accept additional flow. It may also include additional and/or upgraded treatment processes that are more robust and able to be more resilient to climate change. This section of the Report provides a review of the historical WWTP flows; a projection of future capacity requirements that the plant will need to meet over certain times; an estimate of when the expansion will be required; and, the identification of the required WWTP infrastructure upgrades for this expansion. 3.2 Review of the WWTP Historic Flows The Town developed a database consisting of minimum, average and maximum daily flows as measured at the WWTP between 1998 and This represents a total of 20 years of data. Figure 1 at the next page illustrates the minimum, average and maximum flows received at the WWTP from 1998 to For each year, the minimum flow represents the minimum daily flow recorded during the year and the maximum flow represents the maximum daily flow recorded JLR No.: Revision: 0

7 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant during the year. The annual average daily flow represents the total volume of wastewater treated by the plant during the year divided by 365 days. It should be noted that the rated capacity of the WWTP (as per the C of A) is 7.9 MLD (average day flow) and 22 MLD (peak day flow). 35,000 Annual Wastewater Treatment Plant Flows (m 3 /day) 30,000 25,000 20,000 15,000 10,000 5,000 0 Min m³/day Max m³/day Mean m³/day/unit Figure 1: WWTP Flows (m 3 /d) 1998 to 2017 The following are some key observations from the analysis of the data: 1. The annual average daily flows for the 20 year period have remained relatively constant at approximately just above 5,000 m 3 /d, even though the Town has measurably grown over that period; 2. The annual maximum daily flows throughout the years are typically approximately 15,000 m 3 /d but are highly variable. For example, flows of over 27,000 m 3 /d were recorded in 2014 and 11,000 m 3 /d in As would be expected, all maximum flows were recorded during the spring season; 3. The annual minimum daily flows throughout the years are relatively constant. For year 2011 and 2012, the annual minimum daily flows were slightly lower and this could be explained by the fact that these were drier years. JLR No.: Revision: 0

8 Resiliency Plan Wastewater Treatment Plant Final Version 4. It is clear that flows (peak flows in particular) are highly influenced by past climatic conditions. Daily flows of wastewater for the period between 2012 and 2016 are shown in Figure 2 below. 25, Wastewater Treatment Plant Daily Flows (m 3 /d) 20, , , , Jan 1 Jan 11 Jan 21 Jan 31 Feb 10 Feb 20 Mar 2 Mar 12 Mar 22 Apr 1 Apr 11 Apr 21 May 1 May 11 May 21 May 31 June 10 June 20 June 30 July 10 July 20 July 30 Aug 9 Aug 19 Aug 29 Sept 8 Sept 18 Sept 28 Oct 8 Oct 18 Oct 28 Nov 7 Nov 17 Nov 27 Dec 7 Dec 17 Dec 27 Raw Influent Flow m3/d 2012 Raw Influent Flow m3/d 2013 Raw Influent Flow m3/d 2014 Raw Influent Flow m3/d 2015 Raw Influent Flow m3/d 2016 Figure 2: WWTP Daily Flows for Period between 2012 and 2016 Table 1 below provides a summary of the average and maximum flows at the WWTP for years 2008 to 2017 as well as the percentage of current WWTP capacities for dry and wet weather conditions. Year Table 1: Average and Maximum Flows at the WWTP from Year 2008 to 2017 Average Flow m³/day Maximum Flow m³/day % of Plant Capacity Dry Weather Conditions % of Plant Capacity - Wet Weather Conditions ,987 24, % 109.8% ,330 13, % 61.1% ,960 15, % 71.7% ,748 17, % 79.4% ,055 14, % 66.3% ,052 15, % 69.7% ,098 26, % 120.7% ,711 10, % 50.0% ,319 15, % 72.5% ,340 29, % 135.0% JLR No.: Revision: 0

9 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Table 2 below presents the most recent 5 year and 10 year averages for the average and maximum flows recorded at the WWTP. Table 2: 5 and 10 Year Averages for the Average and Maximum Day Flows Period Average Flow (m 3 /d) Maximum Flow (m 3 /d) Average for period between 2013 and 2017 (5 year-period) 5,904 19,705 Average for period between 2008 and 2017 (10 year-period) 5,760 18,396 Table 3 below summarizes the average unit flow per day per household for the minimum, average and maximum flows recorded over different periods of time. Period Table 3: Average Unit Flows per Day per Household for Various Periods Minimum (m³/d/unit) Maximum (m³/d/unit) Average (m³/d/unit) (20 years) (10 years) (5 years) Table 3 shows that the average flows per household have remained relatively constant or have slightly decreased over the years. From 2013 to 2017 (recent 5 years), the average flow per household is m 3 /d/unit. This value has been utilized to calculate future average flows at the WWTP. Table 3 also shows that maximum day flows per household have been relatively constant over the years, confirming that growth is not the largest factor impacting maximum day flows. Other factors (i.e. weather and spring melt) have the largest impact on maximum day flows. 3.3 Population Growth Since the 1980s, the Town has experienced strong growth and this growth can be tracked several ways. The Municipal Property Assessment Corporation (MPAC) produces the tax roll for the Town annually which identifies the number of households within the Town. The MPAC data shows that the number of households in 1990 was 2,833 and that this increased an average of 63 households each year to a total of 4,462 households in The Town s growth can also be tracked by building permits. The building permit records show that the permits issued for new households each year varied from 23 in 1991 to 142 in 2008 with an average of 76 households per year. Lanark County has also been studying growth within the County and produced draft population projections for Carleton Place. For the next 25 years, the County s study predicts the Town will grow by 310 people (135 households) per year with a low growth scenario and 414 people (180 households) per year with a high growth scenario. JLR No.: Revision: 0

10 Resiliency Plan Wastewater Treatment Plant Final Version Based on all the information available, a growth rate of 150 households per year was assumed to predict future flows. It is important to note that the timing for an actual expansion at the WWTP will be triggered by flows which are determined by growth rather than a fixed calendar year. If growth occurs faster or slower than the anticipated 150 households per year, then the timing for the expansion can be adjusted accordingly. 3.4 Proposed Future Capacity of the WWTP Based upon the assumption that the average dry weather flow will increase every year by 197 m 3 /d (i.e., 150 households x m 3 /day per household), the capacity of the WWTP will need to be increased from its current capacity of 7.9 MLD to 11.8 MLD in order to accommodate a future 20 year period from the time that the current capacity is reached. This will require various upgrades to certain components within the plant in order to accommodate the total required future treatment capacity of the plant. As indicated earlier, the analysis of the historical data has shown that even though the Town has grown in population and the collection system has expanded in the previous years, the highest maximum day flows have remained approximately the same. This indicates that the continuously expanding collection system does not contribute significantly to the maximum day flows and other factors such as weather have a much larger impact. The Town regularly undertakes sewer lining and other measures to reduce Inflow and Infiltration (I/I) flows in the collection system and is also planning the installation of new permanent flow monitoring stations at key locations along main trunk sewers. This will provide valuable data to the Town in its ongoing efforts to monitor and reduce I/I flow over the coming years. The major processes that make up the WWTP and their associated sub-systems and components are generally divided into two (2) categories: those designed for the dry weather flows (DWF) and those designed for wet weather flows (WWF). Table 4 below summarizes the current and new proposed capacities for these major processes. Table 4: Proposed Capacities for All Major Processes System Design Basis Current Capacity (MLD) Fine screening DWF and WWF 56 MLD 56 MLD Sewage pumping 26 MLD DWF and WWF (n+1 configuration) Degritting DWF and WWF 20 MLD 30 MLD Primary clarifiers DWF 10.4 MLD 15.6 MLD Physical-chemical Proposed Capacity (MLD) 30 MLD (n+1 configuration) WWF 11.6 MLD 11.6 MLD clarifiers Aeration tanks DWF 7.9 MLD 11.8 MLD Secondary clarifiers DWF 10.4 MLD 15.6 MLD Tertiary filtration DWF and WWF Not applicable 27.2 MLD UV disinfection DWF and WWF 11.0 MLD 27.2 MLD JLR No.: Revision: 0

11 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant This information about the current capacity was obtained from the current amended Certificate of Approval (C of A) Municipal and Private Sewage Works Number FZT4A October 3, The following conditions are included as part of the C of A: 1. Operate the works within the rated capacity of the works (7,900 m 3 /d during dry weather conditions) and within the Peak Flow rate of the works (22,000 m 3 /d during wet weather conditions). 2. Operate the works such that the physical/chemical clarifiers are brought on line and operated only when raw sewage flow to the works exceeds 10,400 m 3 /d (i.e., during wet weather conditions). 3.5 Timing of the Upgrades As indicated earlier, the average flow at the WWTP over the period from 2013 to 2017 was 5,904 m 3 /d. Based upon the assumption that the average flow will increase every year by 197 m 3 /d corresponding to 150 households x m 3 /d/unit, it was possible to develop the curve illustrated in Figure 3. The following assumptions were also made: 1. The Town will initiate a Class Environmental Assessment (Class EA) process (and any other required planning steps) for an expansion of the WWTP once approximately 90% of the current rated capacity is attained. 2. A period of approximately 5-years will be required from the start of the Class EA process to the time of commissioning of the expanded WWTP (this includes all study, design and construction activities required to expand the plant). 3. A future expanded plant will be able to service the Town for 20 years thereafter consistent with Class EA guidelines for these types of facilities. JLR No.: Revision: 0

12 Resiliency Plan Wastewater Treatment Plant Final Version Figure 3: Historic WWTP Flows and Predicted Growth between 2008 and 2050 JLR No.: Revision: 0

13 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Based on Figure 3, it is possible to identify key dates for the Class EA process initiation and plant upgrades completion. These are summarized in Table 5 below: Category of Works Headworks (raw sewage pumping, degritting system and primary clarifiers) Secondary treatment (aeration tanks and secondary clarifiers) Tertiary treatment UV disinfection Tertiary treatment Cloth filtration or other technology Table 5: Plant Expansion Phasing Recommended Start Date for Class EA Process Plant Expansion Completion Year Next Expansion Biosolids management Definition of Plant Upgrades A summary of proposed plant upgrades for a future capacity expansion is presented in Table 6 below: Table 6: Proposed Plant Upgrades for Capacity Expansion Process/System Proposed Capacity Proposed Upgrades Inlet sewer n/a Integration of the two (2) 350 mm diameter force mains from the Highway 7 Pumping Station Fine screening 30 MLD No work proposed. Sewage lift pumps 30 MLD (n+1 configuration) Replace all existing pumps with new dry pit submersible pumps, complete with associated mechanical process, electrical, I&C and SCADA. Degritting 30 MLD Install a third TeaCup degritter in the headworks building extension identical to the two (2) existing ones complete with associated mechanical process, electrical, I&C and SCADA work. Primary clarifiers 15.6 MLD Build a third primary clarifier identical to the two (2) existing ones complete with associated civil, structural, mechanical process, electrical, I&C and SCADA work. Physicalchemical clarifiers 11.6 MLD No work proposed. Aeration tanks 11.8 MLD Build a fourth aeration tank slightly bigger than tanks Nos. 2 and 3 complete with associated civil, structural, mechanical process, electrical, I&C and SCADA work. JLR No.: Revision: 0

14 Resiliency Plan Wastewater Treatment Plant Final Version Process/System Secondary clarifiers Tertiary treatment (UV disinfection) Tertiary treatment (Filtration) Proposed Capacity Proposed Upgrades 15.6 MLD Build a fourth secondary clarifier identical to the three (3) existing ones complete with associated civil, structural, mechanical process, electrical, I&C and SCADA work MLD Build a new building (adjacent to the existing building) which will house a new UV disinfection system complete with associated civil, structural, architectural, mechanical process, electrical, HVAC, I&C and SCADA work MLD Build a new building which will house a new filtration system complete with associated civil, structural, architectural, mechanical process, electrical, HVAC, I&C and SCADA work. Primary digester 880 m 3 Modify the primary digester piping system so that digested sludge can be transferred to the existing storage tank or to the proposed storage tank. Secondary digester 826 m 3 Transform the secondary digester into a primary digester complete with associated structural, mechanical process, electrical, I&C and SCADA work. Storage tank 1,900 m 3 Build a new bio-solids storage tank complete with associated civil, structural, mechanical process, electrical, I&C and SCADA work. DAF unit n/a Install a new DAF in the headworks building extension complete with associated mechanical process, electrical, I&C and SCADA work to manage the WTP residuals. Headworks building Chemical storage building n/a n/a Build an extension to the existing building to house the new degritter and the new DAF unit complete with associated civil, structural, architectural, mechanical process, electrical, HVAC, I&C and SCADA work. Build an extension to the existing building complete with associated civil, structural, architectural, mechanical process, electrical, HVAC, I&C and SCADA work. Electrical n/a Modify main electrical entrance and MCCs and replace the existing backup generator and transfer switch to reflect additional loads. JLR No.: Revision: 0

15 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant The current discharge effluent limits identified in the current Certificate of Approval (C of A) are presented in Table 7 below. Table 7: Treated Effluent Limits Average Concentration Treated Effluent Parameter Effluent Limit (mg/l) CBOD5 25 Total Suspended Solids 25 Total Phosphorus 1 Total Ammonia (Ammonia + Ammonium) 4 (May 15 to September 30) Nitrogen Based upon information obtained from the Water Pollution Control Plant-Capacity Expansion Master Plan prepared in 2011 (Stantec, 2011), discussions with the MOECC at that time indicated that potential changes to the current effluent limits would be put in place as part of the next WWTP expansion. The changes identified in that document are summarized below: 1. Total Phosphorus: 0.2 mg/l for the months of June, July, and August; 0.3 mg/l for the rest of the year; 2. Total Ammonia: 3.63 mg/l for the months of June, July, and August; 15 mg/l for the rest of the year; 3. Acute Lethality: year-round testing to show effluent is non-acutely lethal. It had been determined at that time that the more stringent requirement for Total Phosphorus would necessitate the implementation of tertiary treatment. Based on an analysis of the historic data for Total Ammonia and Total Phosphorous, these two (2) parameters have always met the current effluent limits. The above-mentioned limit for Total Ammonia is not expected to be a problem after the plant expansion. As for the Total Phosphorous, the WWTP currently produces an effluent with a Total Phosphorous concentration which varies between 0.2 and 0.3 mg/l. It should be noted that as per MOECC Guidelines, Policy 2 would apply to the Mississippi River. As per Policy 2: "Water quality which presently does not meet the Provincial Water Quality Objectives shall not be degraded further and all practical measures shall be taken to upgrade the water quality to the Objectives. When new or expanded discharges are proposed, no further degradation will be permitted and all practical measures shall be undertaken to upgrade water quality. As per Policy 2, it might become necessary to incorporate additional treatment measures during the design of the WWTP expansion so as to not increase the Total Phosphorous daily loading discharge to the river. In general, since the current TP limit is 1 mg/l it is conceivable that this would be changed to 0.67 mg/l in order to maintain the allowable loading as per Policy 2 (i.e., 7,900 m 3 /day current flow divided by 11,800 m 3 /day future flow x 1 mg/l). The MOECC, however, may actually impose even lower limits simply based on how the plant is currently performing. It would be prudent to assume that, based on the receiving stream and experiences at other similar plants JLR No.: Revision: 0

16 Resiliency Plan Wastewater Treatment Plant Final Version (e.g. Mississippi Mills located downstream) that tertiary treatment will be required as part of a future expansion. CLIMATE CHANGE ANALYSIS 4.1 Introduction Climate change has the potential to alter weather patterns that in turn can have an effect on the ability of the WWTP to maintain its current performance. For example, one of the biggest impacts in the case of the WWTP could be on the plant flows whereby the frequency and severity of storms could produce larger I/I flows in the collection system. Another example could be on the receiving stream. Changing precipitation patterns, temperatures and other climatic conditions could affect the flow and possibly the quality in the Mississippi River. For the purposes of this Report, climate change impacts associated with the following specific conditions have been analyzed: 1. Changes in Precipitation 2. Changes in Temperatures 3. Changes in Frequency and Severity of Wind/Storms Each of these possible changes could impact the WWTP in different ways. The following subsections presents an analysis of predicted changes associated with the climate in Eastern Ontario. Section 5 discusses the potential impacts and Section 6 discusses potential mitigation measures presented with consideration of future plant expansion (as previously outlined in Section 3.0 of this Report). 4.2 Predicted Changes in Precipitation A provincial report Climate change projections for Ontario: An updated synthesis for policymakers and planners 2015 by Jenni McDermid, Shannon Fera, and Adam Hogg provides the following precipitation change prediction for eastern Ontario. Table 8: Precipitation Change Predictions Year Precipitation (1) to +100 mm to +100 mm to +100 mm (1) Average annual precipitation of 920 mm could decrease by 50 mm or increase by 100 mm. Generally, this could mean that winters will be wetter and summers dryer. Note that that the above are not cumulative figures. The Mississippi Valley Conservation Authority (MVCA) also recently began recording precipitation data. Precipitation for the area for year 2016 and year 2017 is presented at Figure 4 and 5. Figure 4 shows precipitation in 2016 (a relatively dry summer) and Figure 5 shows precipitation in 2017 (a relatively wet summer). JLR No.: Revision: 0

17 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Precipitation (mm) Jan 1 Jan 12 Jan 23 Feb 3 Feb 14 Feb 26 Mar 8 Mar 19 Mar 30 Apr 10 Apr 21 May 2 May 13 May 24 June 4 June 15 June 26 July 7 July 18 July 29 Aug 9 Aug 20 Aug 31 Sept 11 Sept 22 Oct 3 Oct 14 Oct 25 Nov 5 Nov 16 Nov 27 Dec 8 Dec 19 Dec 30 Figure 4: Precipitation for Year 2016 (mm) 120 Precipitation (mm) Jan 1 Jan 9 Jan 17 Jan 25 Feb 2 Feb 10 Feb 18 Feb 27 Mar 6 Mar 14 Mar 22 Mar 30 Arp 7 Apr 15 Apr 23 May 1 May 9 May 17 May 25 June 2 June 10 June 18 June 26 July 4 July 12 July 20 July 28 Aug 5 Aug 13 Aug 21 Aug Predicted Changes in Temperature Figure 5: Precipitation for Year 2017 (mm) A provincial report Climate change projections for Ontario: An updated synthesis for policymakers and planners 2015 by Jenni McDermid, Shannon Fera, and Adam Hogg provides the following climate change predictions for eastern Ontario. JLR No.: Revision: 0

18 Resiliency Plan Wastewater Treatment Plant Final Version Table 9: Temperature and Precipitation Change Predictions Year Temperature (1) Increase of 1-2 deg Increase of deg Increase of deg. (1) Temperature predicted to increase 1-2 degrees above the baseline by Beyond 2040, temperature could increase up to 7 degrees depending upon GHG emissions and other factors. Generally, winters will be milder while summers are impacted less. 4.4 Predicted Changes in Wind/Storms Although there is no quantitative information related to predicted changes to wind and storm patterns in Eastern Ontario available at this time, it would be logical to account for the impacts that even current storms today could have on the WWTP and what measures should be put into place to mitigate these events. If the severity and/or frequency of these storm events increases in the future, these measures should still be at least partially effective and can also be updated to account for these changing conditions, if and when needed. DISCUSSION OF POTENTIAL IMPACTS TO THE WWTP 5.1 Potential Impacts from Changing Precipitation As noted in Section 4.1, precipitation amounts could vary from an overall decrease of 50 mm per year to an overall increase of 100 mm per year. In terms of specific impacts to the WWTP, these changes could affect the flow quantity in the Mississippi River either in terms of low flows (impact on assimilative capacity) or high flows (impact on flooding potential). The following discussion focuses on impacts on the WWTP receiving stream flows. The Mississippi Valley Conservation Authority (MVCA) records flows in the Mississippi River at a gauging station located just downstream in the community of Appleton. Figure 6 shows the recorded maximum and minimum river flows from 1922 to JLR No.: Revision: 0

19 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Maximum and Minimum Flows (m 3 /s) Low High Figure 6: Minimum and Maximum Flows in the Mississippi River (1922 to 2017) The maximum flow in the river for each year varies considerably over the years from 280 m 3 /s in 1999 to 50 m 3 /s in Maximum peak flows greater than 220 m 3 /s have been recorded in 1928, 1937, 1961, 1977, 1999 and Minimum flows vary throughout the years. In 2016, the hot dry summer increased water demand and the river reached Level 3 drought conditions with a flow of only 1.6 m³/s. Low flow conditions have occurred in the past (2.2 m 3 /s in 1999 and 2.3 m³/s in 1929) but the 2016 flows are the lowest ever recorded. Daily flows in the Mississippi River for five (5) recent years ( ) are plotted below in Figure 7. This figure illustrates the changes to flows in the river throughout the year for typical, wet and dry years. Year 2013 and 2014 were considered wet years, year 2016 was considered a dry year and year 2012 and 2015 were considered typical years. JLR No.: Revision: 0

20 Resiliency Plan Wastewater Treatment Plant Final Version River Flows (m 3 /s) Jan 1 Jan 11 Jan 21 Jan 31 Feb 10 Feb 20 Mar 2 Mar 12 Mar 22 Apr 1 Apr 11 Apr 21 May 1 May 11 May 21 May 31 June 10 June 20 June 30 July 10 July 20 July 30 Aug 9 Aug 19 Aug 29 Sept 8 Sept 18 Sept 28 Oct 8 Oct 18 Oct 28 Nov 7 Nov 17 Nov 27 Dec 7 Dec 17 Dec 27 Flow(cms) 2012 Flow(cms) 2013 Flow(cms) 2014 Flow(cms) 2015 Flow(cms) 2016 Figure 7: Daily Flows in the Mississippi River (2012 to 2016) The Mississippi Valley Conservation Authority (MVCA) has developed a model that incorporates climate change impacts to precipitation and predicts flows in the Mississippi River. Figures 8, 9 and 10 below show predicted river flows throughout the years based on a dry weather assumption, wet weather assumption and the average weather assumption Dry Weather Jan 1 Jan 11 Jan 21 Jan 31 Feb 10 Feb 20 Mar 2 Mar 12 Mar 22 Apr1 Apr 11 Apr 21 May 1 May 11 May 21 May 31 June 10 June 20 June 30 July 10 July 20 July 30 Aug 9 Aug 19 Aug 29 Sept 8 Sept 18 Sept 28 Oct 8 Oct 18 Oct 28 Nov 7 Nov 17 Nov 27 Dec 7 Dec 17 Dec Figure 8: Predicted River Flows in m 3 /s Dry Weather (2011 to 2099) JLR No.: Revision: 0

21 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Average Weather Jan 1 Jan 12 Jan 23 Feb 3 Feb 14 Feb 25 Mar 8 Mar 19 Mar 30 Apr 10 Apr 21 May 2 May 13 May 24 June 4 June 15 June 26 July 7 July 18 July 29 Aug 9 Aug 20 Aug 31 Sept 11 Sept 22 Oct 3 Oct 14 Oct 25 Nov 5 Nov 16 Nov 27 Dec 8 Dec 19 Dec Figure 9: Predicted River Flows in m 3 /s Average Weather (2011 to 2099) Wet Weather Jan 1 Jan 13 Jan 25 Feb 6 Feb 18 Mar 2 Mar 14 Mar 26 Apr 7 Apr 19 May 1 May 13 May 25 June 6 June 18 June 30 July 12 July 24 Aug 5 Aug 17 Aug 29 Sept 10 Sept 22 Oct 4 Oct 16 Oct 28 Nov 9 Nov 21 Dec 3 Dec 15 Dec Figure 10: Predicted River Flows in m 3 /s Wet Weather (2011 to 2099) As illustrated in Figure 10, some years have two (2) spring peak flow events (such as in 2017) and other years have multiple smaller peak events during the spring and fall. In the future, the JLR No.: Revision: 0

22 Resiliency Plan Wastewater Treatment Plant Final Version peak flows in the river under wet weather conditions are predicted to never exceed 250 m 3 /s. Since its construction, the WWTP has experienced two (2) occurrences of very high flows in the river. The maximum flow in the river was recorded at 282 m 3 /d in 1998 and 244 m 3 /d in During these two (2) events, the WWTP did not experience any operational challenges with high flows in the river. In the future, the peak flow in the river is not predicted to exceed 250 m 3 /d. High river flows are not a direct threat to the operation of the WWTP. In summary, based on a review of historical high flows versus predicted high flows, flooding of the WWTP does not appear to be a concern and special flood protection measures would not likely be deemed necessary due to climate change. MVCA s model predicts that river flows in the future (dry weather scenario) could be as low as 1.35 m³/s. In 2016, the hot dry summer increased water usage and the river reached Level 3 drought conditions with a flow of only 1.6 m³/s. Lower flows in the River would result in lower assimilative capacity for the treated effluent from the WWTP. Since tertiary treatment is already a consideration in a plant expansion, it would be a resiliency measure that could address this climate change impact. An increase in precipitation could result in additional flows (both average and peak) to the WWTP. Each spring, both the flows in the river and those received at the WWTP increase and then both decrease after the spring runoff. Figures 11, 12 and 13 illustrate that wastewater flows can significantly increase for short periods with corresponding increase to flows in the river. Flows in the river and wastewater flows to the WWTP are related as they are both directly impacted by precipitation and groundwater levels. The relationship between WWTP flows and river flows is more direct during the spring season as the groundwater level is high and as the soil in saturated. WWTP Flow vs River Flow , , , , , Raw Influent Flow m3/d Flow(cms) Figure 11: WWTP Flow versus River Flow Year 2012 JLR No.: Revision: 0

23 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant WWTP Flow vs River Flow , , , , , Raw Influent Flow m3/d Flow(cms) Figure 12: WWTP Flow versus River Flow Year 2014 WWTP Flow vs River Flow , , , , , Raw Influent Flow m3/d Flow(cms) Figure 13: WWTP Flow versus River Flow Year 2016 Managing peak flows at the WWTP is an already a normal and routine circumstance for operations staff. Provisions at the plant to accommodate flows on a day to day basis will need to be maintained and emergency by-pass facilities will need to be appropriate sized to accommodate future flows including those from growth and those that might result from climate change. It is critical to ensure the plant will continue to be protected from these peak flow events in order to stay operational. JLR No.: Revision: 0

24 Resiliency Plan Wastewater Treatment Plant Final Version 5.2 Potential Impacts from Changing Temperatures Temperatures are predicted to increase in the future with climate change. The warmer temperatures could result in earlier spring melts or more rain during the winter months. Peak flows might actually be lessened as a result but could also have to be managed on a more frequent basis (e.g. more melt events in the winter). Warmer temperatures might also coincide with less precipitation and lower flows in the river which were previously discussed in Section 5.1. Figures 14 and 15 demonstrate that precipitation directly impacts wastewater flows to the WWTP. In 2016, a very dry summer, small rain events are absorbed by the ground and have little impact on the WWTP. However, in 2017, a very wet summer, the larger rain events show a direct impact (increase) to the wastewater flows to the WWTP. Raw Influent Flow vs Precipitation , , , , , , , Raw Influent Flow m3/d Precipitation(mm) Figure 14: Raw Influent Flow versus Precipitation Year 2016 JLR No.: Revision: 0

25 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant Raw Influent Flow vs Precipitation , , , , , , , Raw Influent Flow m3/d Precipitation(mm) Figure 15: Raw Influent Flow versus Precipitation Year Potential Impacts from Changing Winds/Storm Events Wind and storm events could impact the WWTP operation regardless of whether they increase in severity and frequency in the future (e.g. ice storms in the past have impacted many facilities in the area). It is logical to expect that with changing conditions (such as increased temperatures) that these types of events could become more prevalent and additional resiliency measures could be put in place by the Town to protect against these types of events. These events could impact the infrastructure at the WWTP such as the main electrical service, the delivery of services, communications and transportation. Similar to increased precipitation, these events could also impact the amount of I/I flows in the collection system and the raw influent flows at the WWTP. POTENTIAL RESILIENCEY PLANNING MEASURES 6.1 Discussion of Findings Available information relating to climate change within the vicinity of Carleton Place suggests that temperatures will increase and the total precipitation in the region could marginally increase or decrease over the next 50 years. Storm events may also become more severe and/or more frequent. Generally, the winters will be wetter (and with the increasing winter temperature more of the precipitation will be rain instead of snow) and the summers will be dryer. These conditions have the potential to affect the flows in the collection system and ultimately the flows received by the WWTP and the flows in the receiving stream. Based on a review of the available climate change information and a review of the current WWTP configuration, the predicted effects are not considered to be severe to say an extent JLR No.: Revision: 0

26 Resiliency Plan Wastewater Treatment Plant Final Version that would require investment significantly beyond what would be planned for a future expansion. There are, however, some resiliency measures that would be prudent for the Town to plan for in the future either as a separate undertaking and/or as part of the planning of a future plant expansion. 6.2 Potential Resiliency Planning Measures Table 10 summarizes potential climate change effects, potential resulting impacts to the WWTP and some possible resiliency measures that the Town could consider putting into place to counteract these impacts. Table 10: Climate Change Effects, Potential Impacts and Possible Resiliency Measures CLIMATE CHANGE EFFECT POTENTIAL IMPACTS TO WWTP POSSIBLE RESILIENCY MEASURES Changes to Precipitation (both increases and decreases) Higher overall precipitation amounts throughout the year Lower precipitation amounts in the summer Higher precipitation in the spring causing higher flows in the River Increases to Temperatures Increase in the air temperature Increase in the air temperature Increases in the air temperature causing early spring melts and/or more melts in the winter More Severe Winds/Storms Severe storms in the region during the Increase to inflow and infiltration increasing peak flows received at the plant Lower river flows resulting in lower assimilative capacity which could trigger the need for more stringent treated effluent limits Predicted high flows are not anticipated to be a problem in terms of plant flooding Could impact the plant s aeration system. Additional odour generation from the plant Increased need to bring wet weather treatment system into service throughout the year Interruption of access to the WTP such as chemical - Implement plant expansion. - Ensure sufficient emergency by-pass capacity. - Continue efforts to reduce Inflows and Infiltration in the collection system. - Implement tertiary treatment as part of a plant expansion project. - No action required. - Ensure sufficient aeration system capacity as part of a future plant upgrade. - Provide additional odour control systems as part of a future plant expansion. - Develop appropriate contingency plans JLR No.: Revision: 0

27 Corporation of the Town of Carleton Place Resiliency Plan Wastewater Treatment Plant CLIMATE CHANGE EFFECT summer and/or ice storms during the winter Larger storms causing larger precipitation and inflow in the collection system POTENTIAL IMPACTS TO WWTP deliveries and/or interruption of electrical grid for extended periods of time Larger wet weather flows received at the plant POSSIBLE RESILIENCY MEASURES - Provide enough storage for each chemical and secure an alternative chemical supplier for each chemical utilized. - Review backup power system capacity and flexibility and upgrade as required. - Implement plant expansion. - Ensure sufficient emergency by-pass capacity. - Continue efforts to reduce Inflows and Infiltration in the collection system with program such as sewer lining and continuous flow monitoring for example. CONCLUSION/RECOMMENDATIONS The following are some of the conclusions and recommendations resulting from a review of the Town of Carleton Place WWTP in terms of potential impacts from future climate change: The WWTP capacity will need to increase in the future to accommodate population growth. This growth needs consideration when evaluating the effects of climate change as both will impact the facility in a similar manner. It has been determined that some of the infrastructure required to accommodate growth could assist in establishing a facility that is more resilient to climate change; The predicted effects of climate change alone on the operation of the Town s WWTP are not considered to be overly severe (particularly compared to the impacts from growth) and should not result in investment significantly beyond what may be planned for growth in the future; There are some measures that could be undertaken by the Town to improve the WWTP s resiliency to climate change these have been outlined in Section 6.2. It is recommended that the Town consider implementation of these measures at the appropriate time; The Class EA process that will need to be undertaken prior to the next expansion will offer an opportunity to study and identify potential additional resiliency measures based on additional data that will be available at the time. JLR No.: Revision: 0

28 Resiliency Plan Wastewater Treatment Plant Final Version This report has been prepared for the exclusive use of Corporation of the Town of Carleton Place, for the stated purpose, for the named facility. Its discussions and conclusions are summary in nature and cannot be properly used, interpreted or extended to other purposes without a detailed understanding and discussions with the client as to its mandated purpose, scope and limitations. This report was prepared for the sole benefit and use of Corporation of the Town of Carleton Place and may not be used or relied on by any other party without the express written consent of J.L. Richards & Associates Limited. This report is copyright protected and may not be reproduced or used, other than by Corporation of the Town of Carleton Place for the stated purpose, without the express written consent of J.L. Richards & Associates Limited. J.L. RICHARDS & ASSOCIATES LIMITED Prepared by: Reviewed by: Christian Thibault, P.Eng., ing. Senior Environmental Engineer Brian Hein, P.Eng. Executive Director Chief Environmental Engineer JLR No.: Revision: 0

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