Review of Final Report: Phosphorus Reduction Action Plan Study, Duffin Creek WPCP. Mr. Al Saikkonen, PE, BCEE, Senior Environmental Engineer

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1 Review of Final Report: Phosphorus Reduction Action Plan Study, Duffin Creek WPCP Mr. Al Saikkonen, PE, BCEE, Senior Environmental Engineer

2 Review of Final Report Phosphorus Reduction Action Plan Study, Duffin Creek WPCP OVERVIEW BACKGROUND The Regional Municipalities of Durham and York (Regions) jointly own and operate the Duffin Creek Water Pollution Control Plant (WPCP) located in Ajax, Ontario. The WPCP serves a service area that includes all of the Town of Ajax, the City of Pickering and approximately 80% of the Region of York, with a combined population of approximately 1.1 million people. The Town of Ajax is within Durham Region. The WPCP is classified as providing an advanced level of secondary treatment, as secondary treatment level pollutants (BOD, TSS and some Phosphorus) are removed. Some phosphorus is removed from effluent as a result of chemical addition to the primary and secondary clarifiers. 1 After secondary treatment, and currently operating at approximately half of its rated hydraulic capacity, the WPCP currently discharges approximately 4,000 kg/month ( average) of total phosphorus (TP) to the Ajax nearshore. When operating at full flow in the future, it is estimated to discharge approximately 11,300 kg/month of TP if current operational practices continue. The Town of Ajax s shoreline abuts the WPCP s effluent outfall into the lake. This shoreline is impacted by nuisance algae in the summer season. Algae growth is exacerbated by phosphorus concentrations in the lake water. As a result of a Part II Order Request to the Minister of the Environment and Climate Change (MOECC) made by the Town of Ajax in relation to the Region s Schedule C Municipal Class EA, the Minister of the Environment ordered the Regions to prepare and submit a Phosphorus Reduction Action Plan study report to the MOECC (PRAP Report). The PRAP Report provides data and information requested in the Minister s Order, evaluates alternative methods to reduce the historical amounts of phosphorus being discharged by the WPCP and makes recommendations for short, medium and long term corrective action. The PRAP Report was completed by the Regions in January, The chemicals added to WPCP s clarifiers convert soluble phosphorus into particulate form, which then settles in the primary and secondary clarifiers along with settleable biomass solids that result from the secondary biological treatment process. The secondary effluent is disinfected with sodium hypochlorite and discharged though a one km long outfall into Lake Ontario. Biosolids along with chemical solids are digested, dewatered and incinerated onsite. 1

3 ELEMENTS OF THE MOECC ORDER In accordance with the MOECC order dated April 14, 2016, the PRAP must include: a) Data from the past five years on phosphorus concentrations and loading (item 2a); b) A desktop study of optimization of plant operations to reduce phosphorus in the WPCP effluent (item 2b); c) A study of new methods that could be employed to reduce phosphorus in the WPCP effluent (item 2c); d) Based on a and c above, considerations of options to reduce TP in the WPCP effluent including an indication of how phosphorus and loadings would be impacted by each option (item 2d); e) A determination of an option that will result in the lowest achievable level of TP levels in the effluent, including an assessment of the operating implications of, and the modifications and costs required to achieve such reductions (item 2e); f) A strategy to reduce the amount of soluble reactive phosphorus (SRP) in the WPCP effluent in the short, medium and long term including a method for determining how to quantify SRP reductions, and a description of methods to be used to measure the reductions (item 2f); g) Identification of the seasonal window of nuisance Cladophora algae growth and how TP in effluent may be further reduced during this time (item 2g); and h) A determination of the feasibility of achieving a permanent (or ongoing) annual average concentration of 0.35 mg/l of TP in effluent, as well as a TP load of 190 kg/d based on an annual average (item 2h). A copy of the Minister s Order is attached as Appendix 1 to this report. REVIEW OF PRAP REPORT AND SUPPORTING TECHNICAL MEMOS EXECUTIVE SUMMARY The PRAP Report was prepared by the Regions for the purpose of evaluating alternatives, developing costs and recommending strategies for reducing the concentrations of phosphorus in the effluent of the WPCP. Phosphorus is a nutrient, that when discharged to a water body providing sufficient light and a hard substrate, results in algae growth. The Town of Ajax s shoreline abuts the discharge location for the WPCP s effluent and the nuisance algae growth observed on the Town s shoreline in summer can be attributed to the phosphorus discharged from the WPCP (Auer 2018). The PRAP Report was completed in early January 2018 and was reviewed by the Town and the Town s engineering and scientific consultants. The results of this review are summarized herein: The PRAP Report reviews the history of operation of the WPCP and notes the annual TP and SRP in the WPCP s discharge for It is noteworthy that these effluent concentrations have generally increased over the seven year timeframe. 2

4 The nuisance algae observed on the Town s shoreline has been observed every year, however the degree of nuisance varies every summer. The WPCP has a design rated capacity of 630 million litres per day (MLD) annual average flow. Currently, the WPCP is operating at slightly more than 50% capacity. The Regions estimate that flows will increase annually until the rated capacity of 630 MLD is reached in As the flows increase, the quantity of phosphorus discharged to the lake also increases unless concentration of effluent phosphorus decreases. The PRAP Report evaluated three alternatives: o Continue to operate the WPCP as it is currently operating, wherein influent phosphorus is reduced in the WPCP via chemical addition. As the flows increase, the effectiveness of phosphorus removal is expected to decrease such that the current effluent phosphorus concentration would increase from the current TP = mg/l to a concentration of TP = mg/l in o Improve the current operation, referred to as secondary optimization, by modifying the chemical feed and adding a coagulant chemical. A computer model was prepared to predict the results of this along with testing at the WPCP which are currently on-going. The PRAP Report finds that effluent TP in the range of mg/l and SRP in the range of mg/l could be achieved by secondary optimization without adversely impacting other WPCP processes. o Construct a tertiary treatment process downstream of the existing secondary treatment process. Four technologies were evaluated for cost, phosphorus removal effectiveness and constructability. Although the PRAP made no final recommendation for tertiary technologies, the information presented shows most cost effective and best performing phosphorus removal effective technology is ballasted flocculation (trade name Actiflo ). This technology is successfully operating in 25 WPCPs in the U.S. and Canada. The ballasted flocculation process is estimated to produce an effluent in the range of TP = mg/l, SRP = 0.01 mg/l. Although the PRAP evaluated four tertiary technologies on a more or less equal basis, the overall capital costs are felt to be unnecessarily high. The higher than necessary costs primarily result from overly conservative conceptual designs for capacity and redundancy. The PRAP compares secondary optimization and tertiary treatment and acknowledges that tertiary treatment will result in vastly less phosphorus in the WPCP s effluent but concentrates on the higher cost both in capital and operating costs of tertiary treatment. The PRAP Report fails in its most important objective that was described in the MOEE s direction to the Regions. The MOEE s Direction had several elements, the most important of which is stated as include a strategy to reduce the amount of SRP in the WPCP effluent in the short, medium and long term 3

5 Figure 1 presents a timeline from 2012 through Actual annual average effluent SRP (kg/d) is shown for For the future, , the effluent SRP loads to the lake are shown for the three alternatives, i.e. current operating practice, secondary optimization and tertiary treatment. Clearly, current operational practice of secondary optimization does not reduce the amount of SRP over the planning period. In section 9 of the PRAP Report, the Regions recommend a short, medium and long-term plan that implements secondary optimization. The Town of Ajax asks that the MOEE issue effluent TP and SRP limits to the Regions such that the WPCP s effluent TP and SRP reduces over time. Clearly, secondary optimization will not do that, thus tertiary level treatment will be necessary. A commonly available and widely used tertiary technology, ballasted flocculation, is demonstrated, practical and constructible at the WPCP. The Town asks that effluent limits be placed on the Regions that will result in construction of ballasted flocculation based tertiary treatment facilities. PRAP REVIEW COMMENTS The PRAP Report includes an Executive Summary and eight Sections. Four of the PRAP report sections are supported by more detailed information included in appended technical memos. This review provides comments in the order in which information is presented in the PRAP. During the course of the preparation of the PRAP, the Town of Ajax and the Town s consultants attended several workshops with the Regions and their engineering consultant. Additionally, the Town reviewed technical memos and drafts of the PRAP Report. The Town s review comments and the Region s responses are appended to the PRAP Report and associated technical memos. 4

6 TECHNICAL MEMO 1 AND PRAP SECTION 5: PERFORMANCE EVALUATION AND CAPACITY POTENTIAL The Regions first technical memo, TM1, is summarized in Section 5 of the PRAP (collectively referred to here as TM1). TM1 presents the WPCP s design capacity for treating raw wastewater (the influent loading basis of design ), and its history of performance related to effluent phosphorus concentrations and annual average phosphorus concentrations for TM1 also sets out the results of a desktop computer modelling exercise. The modeling exercise was conducted as the WPCP s current annual average flow is projected to approximately double over the next 20 years The input parameters to the model were described in TM1, and the model output was correlated to the actual plant operating data for effluent TP and SRP. The model was then used by the Regions to predict future phosphorus concentrations for both TP and SRP at future flows (630 MLD estimated to occur in year 2041). Tables 1 summarizes the WPCP s historical data ( ) which includes annual average flow, TP, SRP and total suspended solids (TSS) concentrations in the WPCP effluent. Table 2 summarizes the historical effluent total TP and SRP loadings to the lake (kg/d) during the cladophora growth season of April through August At 50% of its rated hydraulic capacity, TM1 makes clear that the WPCP is currently using 73% of its BOD5 treatment capacity and 67 % of TSS treatment capacity. BOD5 is a measure of the organic strength of the influent wastewater. In other words, while the WPCP is currently operating at just half of its maximum rated hydraulic capacity, it is currently using 67-73% of the WPCP s secondary treatment capacity. Year Table 1: Duffin Creek WPCP Historical Annual Average Effluent Performance Flow (ML/d) Effluent TP (mg/l) Effluent TP (kg/d) Effluent SRP (mg/l) Not available Effluent TSS (mg/l) WPCP % Capacity a a 2017 data does not include December and is, therefore, not final or official. Source: PRAP Report Table 5-1 5

7 Table 2: Historical Monthly Average Effluent TP and SRP Loads (kg/d) Month (1) TP SRP TP SRP TP SRP TP SRP TP SRP April May June July August TP Average SRP Average (1) Months indicate Cladophora growth window Source: PRAP Technical Memorandum No. 1, Table 2 In relation to phosphorus, the historical data presented in Table 1 shows that the annual average effluent TP varied between 0.35 and 0.52 over the time frame. It is worth noting that 0.35 mg/l TP, an interim effluent limit proposed for comment by the Minister, was achieved in 2013, but has not been achieved since. Tables 1 and 2 show a general upward trend in WPCP effluent TP and SRP concentrations and loadings to the lake over the timeframe. Technical Memo 4, Table 30 shows the projected annual average WPCP influent flow increasing from present (343 million liters per day (MLD in 2017) to 630 MLD in The WPCP s design rated capacity is 630 MLD annual average flow. As flows increase, a notable decrease in phosphorus removal efficiency can be expected. This relationship is a function of solids removal efficiency, especially the chemical precipitate ferric phosphate, of the final clarifiers. The solids removal efficiency of the WPCP s secondary clarifiers is inversely proportional to the flow. The phosphorus removal efficiency also is inversely proportional to flow as significant portion of the effluent phosphorus is in particulate form. Table 2 presents a compelling volume of data, during the cladophora growth months (April through August ). The table shows monthly average kg/d lake loadings for TP and SRP with an upward trend over that time period. For example, TP loading in 2012 averaged 97 kg/d during the cladophora growth window, which had increased by 2016 to an average of 176 kg/d, on average, for the April August period. For SRP, the April August average was 48 kg/d in 2012 but had increased to 126 kg/d by It should be noted that both the 2012 and 2016 data was based on flow through all three stages of the WPCP, as the Stage 3 tankage was placed into service in

8 Although the TM makes statements of reduced concentrations of effluent TP and SRP over the timeframe, the opposite seems to be the case. Historical data show that both TP and SRP have increased by factors of 1.8 and 2.6 for TP and SRP respectively. Looking ahead, the PRAP relied upon a computer model to project future phosphorus discharges to the lake, for both TP and SRP, based upon data from past performance. To check the accuracy of the model s results, computer model outputs were compared against actual operating data for previous years. As the correlation between the model and historical data appears to be very close, we can assume that the model can accurately predict TP/SRP effluent concentrations when flows are in the range of current flows (i.e. 318 MLD). Next, the computer model was used to predict effluent TP/SRP concentrations under future flow conditions, when the WPCP is operating at its full rated hydraulic capacity (i.e.: 2041 average daily flows of 630 MLD). The model prediction concludes that the effluent TP/SRP concentrations would rise to a future monthly average 0.78 mg/l TP and 0.36 mg/l SRP. At 630 MLD, this is estimated to be 491 kg/d TP and 227 kg/d SRP. The impact on lake loadings is shown on Table 3. Table 3: Historical and Model Predicted Effluent TP and SRP loadings (kg/d) at full build out (630 MLD) (2) Model Predicted Month (1) TP SRP TP SRP TP SRP TP SRP TP SRP TP SRP April May June July August TP Average SRP Average (1) Months indicate Cladophora growth window Source: PRAP Technical Memorandum No. 1, Tab 62 (2) 2041 annual average flow = 630 MLD, computer model estimates TP = 0.78 mg/l and SRP = 0.36 mg/l assumes current WPCP operational practices (i.e. un-optimized operation) Based on both the trend that is clear in the record of historical performance, and the predictions of the Regions desktop computer model, it can be expected that clarifier performance will be negatively impacted as flows increase, leading to less phosphorus removal capacity. The WPCP has already seen phosphorus removal fall from 0.36 mg/l to 0.52 mg/l and this trend is predicted to continue until monthly average TP 0.78 mg/l in

9 When model predicted effluent TP and SRP concentrations are applied to 2041 flows, if the WPCP operates with current practices, the lake loading is predicted to increase approximately by a factor of 4 for TP and 3.6 for SRP during the cladophora growth season from the loads discharged in 2014 (computer model validation year). PRAP SECTION 6 (AND TM 2A AND 2B): ENHANCED PHOSPHORUS REMOVAL THROUGH OPTIMIZED SECONDARY TREATMENT The second technical memo (TM2A and 2B) is summarized in section 6 of the PRAP. Collectively, the results of TM2A, TM2B and the summary presented in Section 6 of the PRAP are referred to below as TM2. TM2A is a requirement of the Minister s Order, and presents the results of a desk top modelling exercise that predicts the ability of the WPCP to improve phosphorus removal by adjusting existing equipment and processes. This evaluation is referred to as secondary optimization as it would modify the operation of the current operation of the existing secondary treatment process at the WPCP. It considers findings from WWTPs of a similar size, that employ chemical feeds for phosphorus removal, and options for optimized secondary treatment which include modifying the current chemical feed practice at the WPCP and the addition of polymer to enhance the chemically based phosphorus removal process. TM2A then examines the relationship between effluent TSS and effluent TP, as TP is typically about 2.5% (by weight) of TSS, and presents the results of a predictive computer model for phosphorus removal when flow through the WPCP is at full hydraulic capacity in 2041 (630 MLD, full WPCP build-out). TM2B reports the findings of field tests that the Regions elected to undertake on a voluntary basis; it was not a requirement of the Minister s Order. The Field Test involved testing each of the four options for secondary optimization, using one of the trains of liquid treatment tankage at the WPCP. The options included: (a) ferrous chloride addition to the primary clarifiers and secondary clarifiers; (b) ferric chloride addition to primary and secondary clarifiers; (c) ferric chloride addition + polymer addition to the primary clarifiers only; and (d) ferric chloride addition + poly addition to primary and secondary clarifiers. The results of Field Testing through November 2017 are reported in Section 6 of the PRAP, although one option remains to be tested. Field Testing is planned to continue through mid-2018, at which time TM 2B will be updated. Additionally, the computer model will be validated against the field testing results and TM 2A will also be updated. The Field Testing identified a problem inherent in attempting to remove phosphorus through secondary treatment, rather than implementing tertiary treatment to remove phosphorus. In particular, phosphorus removal via chemical addition to the primary and secondary clarifiers, can have an adverse effect on the activated sludge based biological (secondary) treatment process. The biological treatment process, referred to as the activated sludge process, removes the organic pollutants in the wastewater when microorganisms use the organic pollutants as food. The growing biomass then settles in the secondary clarifiers with some portion of the settled biomass recycled back the aeration tank such that a stable population of micro-organisms is maintained. The micro-organisms need nutrients to grow. If too much phosphorus is removed by chemical addition, the biomass is starved or undesirable micro-organisms predominate. This can then negatively impact the entire secondary treatment process. The field studies found that the secondary treatment process was negatively impacted if the TP and SRP concentrations in the secondary effluent drops below mg/l and 0.10 and 0.20 mg/l respectively. 8

10 As such, it is concluded that secondary treatment optimization is limited to no less than mg/l TP and mg/l SRP in the effluent to the lake. Applying these TP and SRP concentrations, from optimized secondary treatment to the 2041 average annual flow results future loadings to the lake as shown in Table 4. Table 4: Historic and Field Study Identified TP and SRP Loadings at Full Build Out (630 MLD) with Secondary Optimization (kg/d) (2) Month (1) TP SRP TP SRP TP SRP TP SRP TP SRP TP SRP April May June July August TP Average SRP Average (1) Months indicate Cladophora growth window Source: PRAP Technical Memorandum No. 1, Table 2 (2) 2041 annual average flow = 630 MLD, field testing (secondary optimization) demonstrated effluent TP = mg/l, SRP = Table 4 based on TP = 0.45/mg/l and SRP = 0.20 mg/l When results of secondary optimization field testing predicted effluent TP and SRP concentrations are applied to future 2041 flows, the effluent TP and SRP discharged to the lake is predicted to increase by a factor of 2.3 for TP and 2.0 for SRP during the cladophora growth season when compared to loadings discharged in 2014 (computer model validation year). This assumes that the upper range (TP = 0.45 mg/l and SRP= 0.2mg/l) concentrations are achieved via secondary treatment optimization. Three factors are important to understand in relation to TM2. First, tertiary treatment to remove phosphorus does not have the negative impact on bio-organisms that optimization has been demonstrated to have. The reason for this is simple. Tertiary treatment to remove phosphorus takes place after secondary treatment, and after the micro-organisms have been provided with sufficient phosphorus to grow and maintain a stable population. The location and timing of tertiary treatment mean that it can remove almost all of the phosphorus in WPCP effluent without causing any negative impact on the micro-organisms used in secondary treatment. Second, the Field Testing has made clear that the Regions cannot achieve the interim effluent limit of.35 mg/l that the Minister proposed for comment, using optimization. At best, they can achieve a range of effluent phosphorus concentrations of mg/l for TP. 9

11 The only way to achieve the effluent limit of.35 mg/l is to implement tertiary treatment. Third, the relationship between effluent TSS concentration and effluent SRP that is described in TM2 fails to account for a key component of TP, namely dissolved organic carbon (DOP). ACHIEVABILITY OF AN EFFLUENT TP OF 0.35 mgp/l WITH 2 OPTIMIZATION The WPCP performed field testing of plant operations to validate model predictions of effluent TP levels for five optimization scenarios. The analysis also provided an opportunity to determine required TSS removal for a specified effluent SRP concentration (Figure 1). Figure 1. Relationship between Effluent TSS and Maximum Allowable Effluent SRP (Reprinted from Figure 5-1 of the PRAP Final Report (CH2M 2017). The scenario presented above as Figure 1, and reproduced subsequently as Figure 2a, is based on contributions to TP from the soluble reactive (SRP) and particulate (PP) components of the TP analyte; the dissolved organic phosphorus (DOP) component, a potentially significant contributor to the TP analyte, is not included. The effluent SRP is set at 0.1 mgp/l to avoid nutrient deficiency in the secondary treatment microbial population and attendant disruption of plant operation. Under this scenario, an effluent PP concentration of 0.25 mgp/l and a TSS of 10 mg/l is required in order to achieve an effluent SRP of 0.1 mgp/l. Michigan Tech (MTU) measured DOP in 6 samples collected prior to and during the PRAP field test, reporting a mean concentration of ± mgp/l. Measurements made by the plant yielded a lower result (0.044 ± mgp/l). Proceeding based on the basis of the MTU measurements, for a scenario with an effluent SRP concentration of 0.1 mgp/l and taking DOP into account, the effluent PP must be reduced to 0.15 mgp/l with an effluent TSS of 6 mg/l (Figure 2b). 10

12 Figure 2. Determination of TSS removal efficiency required to achieve an effluent TP of 0.35 mgp/l: (a) as presented in the PRAP Final Report, (b) including MTU DOP in the calculation and (c) including MTU DOP in the calculation and limiting SRP reduction to 0.2 mgp/l to avoid nutrient deficiency in the secondary treatment microbial population. 11

13 Results of field testing demonstrated that nutrient deficiency in the secondary treatment unit s microbial population occurred as SRP approached 0.1 mgp/l and plant performance could not be assured. The PRAP Report concluded that the effluent SRP concentration under optimized secondary treatment would range from mgp/l. Under a scenario where the DOP component is included and an effluent SRP concentration of 0.2 mgp/l is maintained, the required effluent PP and TSS concentrations would be 0.05 mgp/l and 2 mgtss/l, respectively. Effluent TSS concentrations measured during field tests averaged 4.8 ± 2.69 mgtss/l for the three ferric options and 4.6 ± 4.0 mgtss/l for the option yielding the lowest TP concentration (Option 5). Presented here based on DOP measurements made by both MTU and the WPCP (dashed lines in Figure 3), it is demonstrated that the plant would be challenged to achieve the levels of TSS removal required to produce an effluent with a TP of 0.35 mg/l (Figure 3). Figure 3. Mean ± SD effluent TSS concentrations for the options tested in the Duffin Creek WPCP field testing. Option 5 yielded the best effluent TP among the four optimization approaches tested TSS (mg/l) 6 4 Based on WPCP DOP Option 1 Dual point ferrous 3 Dual point ferric 4 Dual point ferric, 1 polymer 5 Dual point ferric, 1 and 2 polymer Based on MTU DOP 12

14 PRAP SECTION 4 (AND TM3): ASSESSMENT METHODOLOGY Technical Memo 3, which is summarized in section 4 of the PRAP (together, TM3) outlines the options that are to be developed for secondary treatment optimization (i.e.: chemical feed alternatives for the precipitation of soluble phosphorus and polymer addition to enhance settleability of the precipitant in the clarifiers), and the alternatives for tertiary treatment that would be capable of further reduction of phosphorus in the effluent. Four alterative tertiary treatment technologies were selected for detailed alternative evaluations, as follow: 1) Ballasted flocculation/clarification (trade name Actiflo ): This technology involves construction of an enhanced clarification process downstream of the existing secondary clarifiers. This process has been commonly used worldwide for this application. It has been successfully applied for the purpose of tertiary level phosphorus removal in over 25 installations if the US and Canada including the installation in Syracuse (Onondaga County), NY in operation since It can be noted that the installation in Syracuse was constructed for the very same purpose, i.e.: tertiary phosphorus removal as secondary effluent phosphorus was severely impacting lake water quality and creating public nuisances resulting from algae growth. 2) Cloth Media Filtration: This technology involves construction of cloth media disc filters downstream of the existing secondary clarifiers. This process has also been commonly used for tertiary filtration that includes phosphorus removal as TSS removal via filtration results in removal of particulate phosphorus; 3) Deep Bed Filtration: This technology is also a filtration process that uses a media bed of granular materials to filter the secondary effluent; 4) Membrane Filtration: This technology is also a filtration process that uses very fine pore media for removal of solid particles. This technology is substantially more complex and expensive to construct but was initially thought to have the highest overall phosphorus removal efficiency. Further evaluations in TM 4 and Section 7 of the Final report found the performance to be equivalent to ballasted flocculation. TM3 next identified the factors that would be considered in the evaluation of the options selected for study. These factors included capital cost, operations and maintenance costs, phosphorus removal effectiveness, reliability, constructability, and carbon footprint. Missing from TM3 was any transparent and replicable process for ranking and weighting the criteria listed. For example, the PRAP was specifically designed pursuant to a Minister s Order to identify methods for better removing phosphorus from effluent. Yet the Regions evaluation appears to place equal weight on carbon footprint as it does on phosphorus removal efficiency, when selecting options to carry forward. These review comments were offered on behalf of the Town but were not accepted by the Regions. This is noted as a point of disagreement in the PRAP. PRAP Report Table 2-1 denotes key areas of consensus and key areas of differences of opinion between the Regions and the Town that were raised during the workshops. 13

15 The results of the assessment process are discussed in section 4 of the PRAP, and the next section below. PRAP SECTION 7 (AND TM4): CONCEPTUAL DESIGN AND ASSESSMENT OF TERTIARY OPTIONS Technical Memorandum 4 is summarized in section 7 of the PRAP (together referred to below as TM4). TM4 develops concept level designs of four tertiary treatment alternatives, from which capital and operating and maintenance cost estimates are then estimated. TM4 undertakes a summary benchmarking exercise, by considering the phosphorus removal effectiveness of certain other WPCPs. TM4 then compares the four tertiary treatment options selected for study (Actiflo/ ballasted flocculation, cloth media, deep bed and membrane filtration) based on the assessment criteria outlined in PRAP section 4. The development of cost estimates for tertiary treatment options includes four major elements as follows: 1) The development of engineering and technical aspects of the tertiary options necessary for preparation of a concept level design for each option. These aspects include siting, hydraulics, interconnections with the existing WPCP structures and the WPCP s outfall pipeline, and power requirements. These aspects appear to be well developed to a level necessary for procurement of equipment vendor quotes, concept level site layouts, major structure sizes etc. 2) Capital cost estimates (Total project costs for planning, design, construction, permitting, commissioning and the Regions staff costs) are summarized as follows in Table 5. Associated O and M costs and extensions to NPV costs are also summarized in Table 5. 3) Operations and maintenance (O and M) costs consider labor, power, chemicals, repair parts etc. using estimating values based on the WPCP s actual costs. Extraordinary costs are also captured for cloth media replacements and membrane media replacements. Utilizing the flow projections over the planning period, costs related to flow are also captured. 4) Using estimated capital costs and annual O and M costs over the planning period, coupled with an escalation rate and cost of borrowed money, the Net Present Worth Values (NPV) for each alternative and sub-alternative (phased or full build construction, seasonal or year around operation) is calculated. Review comments will be provided below on each of these sections of TM4: the development of cost estimates, the selection of WPCPs against which to benchmark, and the evaluation of the four tertiary treatment options. Review Comments on Benchmarking The results of a 2011 Water Environment Research Foundation (WERF) study are reviewed in this section. The WERF study obtained operating data from 9 WPCPs in the US and Canada that had tertiary treatment facilities and relatively low effluent operating permit limits for TP. The study reported the plants operating results for monthly and annual average effluent TP concentrations. Of the 9 plants, 7 had tertiary filters, one had membranes and one had enhanced clarification. None of the plants reviewed in the WERF study utilized ballasted flocculation. Reported monthly average effluent TP concentrations ranged from 0.03 to 0.22 mg/l. 14

16 It is noteworthy that this review is based on out-of-date data and does not include plants that would be similar to the WPCP. In particular, the review does not include any data from Onondaga County (Syracuse), NY, nor any of the 25 other plants in the US and Canada that have ballasted flocculation clarification built for the purpose of tertiary phosphorus removal. Review Comments on the Development of Cost Estimates In our opinion, the Regions have made a series of assumptions in TM4 that result in a significant and unnecessary over-estimation for the cost of tertiary treatment facilities. The Regions have selected an unnecessarily high hydraulic flow (in particular, the peak day in 2041) for which to design tertiary treatment. This choice is not supported by any assessment of the environmental impact of various design flow options. As a result, costs are overestimated. The WPCP s historical database was used to develop flow peaking factors (annual average daily flow (ADF), maximum month flow, peak day flow and peak hour flow). These factors were then applied to the WPCP s design rated ADF of 630 MLD. The Regions selected a conservative future peak day flow as the design basis of the tertiary treatment facilities. This selected hydraulic capacity is 1,070 MLD, the estimated peak flow day in 2041: the wettest day of the wettest month in 2041, with the WPCP running at full capacity. Flow projections, over time, estimate that this peak day flow will occur in year In contrast, the 2041 peak day flow is estimated to be 1070 MLD whereas the 2041 maximum month (wettest month) flow is estimated to be 760 MLD. The capital cost impact would be closely associated with the hydraulic capacity. The peak day hydraulic capacity is 40% higher than the maximum month hydraulic capacity. Thus, the capital cost for the recommended design is expected to be significantly higher. The capital costs for the tertiary facilities would be needlessly high if the peak hydraulic capacity is based on future peak day flow vs a more conservative maximum month flow. A sensitivity analysis (TM 4 table 3) shows the estimated TP lake loadings based on tertiary facilities with capacities for maximum month or peak day flows. This issue can be summarized as follows: - Year 2041 tertiary effluent TP if tertiary facilities are sized for peak day flow = 32 kg/day - Year 2041 tertiary effluent TP if tertiary facilities are sized for peak month flow = 31.5 kg/d - Year 2041 secondary effluent TP if current WPCP operations is not optimized = 491 kg/d - Year 2041 secondary effluent TP if current WPCP operations are optimized = 284 kg/d This indicates that a negligible overall phosphorus removal improvement from tertiary facilities sized for peak day flow does not likely warrant the significant increase in capital cost. It is noteworthy that the Regions themselves, in the Environmental Study Report dated November 2013, section 9, page 9-12 used 630 MLD, not 1,070 MLD. In summary, the Regions should at most assess the cost of tertiary facility design based on year 2041 peak month flow (760 MLD) vs peak day flow (1071 MLD), unless an assessment of the environmental impact of the various design flow options indicates that a higher design flow is required in order to address environmental impact. 15

17 2) Building Redundancy for the peak flow day in the year The Regions have assumed the tertiary facilities need to be designed to treat the peak day flow with one train of tankage or filter out of service on the peak flow day in the year As such, the tertiary facilities capital costs are based on redundant ballasted flocculation clarifiers or filter units. THIS APPROACH IS OVERLY CONSERVATIVE AND COSTLY WHEN APPLIED TO TERTIARY FACILITIES. The need for standby tertiary trains of tankage or filter units during peak day flow is not essential as the secondary effluent receives partial phosphorus removal upstream of the tertiary facilities. As such, occasional wet weather related, or equipment out of service bypasses of tertiary treatment likely have little or no environmental impact on lake water quality. Additionally, if seasonal operation of the tertiary facilities is practiced, major equipment repairs can easily be conducted during the off season, which is 7.5 months annually. 3) Choosing a decentralized design magnifies the over-estimation of costs. As noted above, the Regions have assumed they must treat the peak day flow in 2041 with one unit out of service. When this choice is combined with the Regions preference for decentralized treatment, this means an inordinate number of redundant treatment trains. For example, for ballasted flocculation (Actiflo), the centralized ballasted flocculation system would include 6 duty + 1 standby = 7 total trains of tankage and equipment whereas the decentralized system would include 8 duty + 5 standby = 13 total trains. This are shown in TM 4 figures 10 and 21. The cost implications of these choices do not appear to have been fairly reflected in the cost estimates, when centralized and decentralized alternatives are compared. As an example, the decentralized cost estimate for Actiflo does not seem to reflect the additional cost of building five separate structures, to house 13 treatment trains, as compared to the cost of building just one structure to house 7 centralized Actiflo treatment trains. 4) Phased construction unnecessarily inflates cost. The evaluations consider phased construction of the tertiary facilities. In order to evaluate this, the Regions estimated WPCP annual average flows over the planning period ( ). If construction were to be phased, a second phase would need to be initiated where the flows approach 85% of full rated flow (i.e. 85% of 630 MLD = 535 MLD). 535 MLD is estimated to occur in year Thus, it is recommended that phased construction will result in higher costs and should be eliminated from further consideration. 5) Annual treatment for a year around operation unnecessarily inflates cost. At the request of the Town of Ajax, the Minister s Order directed the Regions to consider the option of seasonal treatment, during the months that phosphorus discharges can cause algae to grow, as an alternative to year round treatment. Technical Memorandum 5 ( TM5 ) identifies the cladophora growth season as mid-april through the end of August. TM5 concludes that growth occurs from May through late August. A clearing time of two weeks is added prior to May 1 to allow for phosphorus within the nearshore to be cleared out of the nearshore, leading to a treatment period of 4.5 months. The PRAP section 10.2 develops the seasonal tertiary treatment O and M costs for ballasted flocculation and cloth media filters based on 4.5 month of operation for power 16

18 and chemicals and 6.5 months for operating and maintenance labor. The longer period for labor was used to allow for system start-up and shut down time. Outside of this growth window, treatment to remove phosphorus will do nothing to reduce algae growth. As such, the cost of treatment outside of the growth window is not supported. The Regions were asked to confirm a point of consensus that treatment need only occur during the algae growth season (4.5 months annually). The Regions declined, noting that Environmental Compliance Approval limits have historically been annual. The MOECC should be asked to impose two different effluent limits for phosphorus, a more stringent limit during the algae growth window, requiring tertiary treatment, and a less stringent limit for the balance of the year. This would ensure environmental protection objectives are met during the months when phosphorus is causing adverse impacts, and avoid the need to spend money unnecessarily, treating effluent during months when it has no environmental benefit. Therefore, it is believed that only seasonal operation of tertiary treatment facilities is necessary, during the 4.5 month period from April 15 August 30, and that little or no environmental benefit would result from year around operation. The MOECC should be asked to revise ECA for the WPCP to require tertiary treatment on a seasonal basis, from April 15 August 30 th, and to permit optimized operation outside of the seasonal window. 6) Summary of Estimated Costs Table 5 summarizes the cost estimated for capital, O and M and Net Present Worth for the combination of alternatives and sub-alternatives that is believed to be the best fit. The best fit combination includes centralized full build out versus building the decentralized tertiary facilities in two phases wherein the second phase would need to begin at year 15 in the 20 year planning period. The best fit also includes seasonal operation as little environmental benefit would result from year around operation of tertiary facilities and at substantial additional cost. Table 5: Summary of Tertiary Treatment Alternative Costs Total Capital Cost Total Design Year O&M Cost Net Product Value of O&M Cost Net Product Value of Lifecycle Cost Ballasted Flocculation Decentralized Full Build Out Seasonal Operation Cloth Media Filter Deep Bed Filter Membrane Filter Centralized Full Build Out Seasonal Operation Ballasted Flocculation Cloth Media Filtration $171,006,000 $202,538,000 $269,871,000 $463,981,000 $160,361,000 $208,699,000 3,497,000 1,416,000 3,447,000 1,350,000 47, ,569,000 45,767,000 21,496,000 $218,452,000 $226,107,000 $206,068,000 $230,145,000 17

19 Review Comments on Assessment of Tertiary Treatment Options The evaluation includes as overall assessment of the tertiary treatment options (Actiflo / ballasted flocculation clarification, cloth media, deep bed and membrane filtration). Eight assessment criteria are discussed (phosphorus removal effectiveness, reliability, O&M requirements, future proofing, carbon footprint, costs (capital, O&M and lifecycle) and $/kg TP removed. No objective or traceable ranking or weighting is offered by the Regions and the Regions seem to rely heavily, without rationale, on carbon footprint rather than any other criteria, including phosphorus footprint, phosphorus removal efficacy, technical performance or cost. All four tertiary treatment options are found to be equivalent, in relation to four of the eight assessment criteria: reliability, constructability, O&M requirements and future proofing. The important criteria from the perspective of improving conditions in the nearshore is the how well each technology does at reducing phosphorus discharges: the phosphorus removal efficiency of each option. In this respect, Actiflo or ballasted flocculation clearly performs the best, achieving the Ability to remove phosphorus to the lowest achievable level. From the data and the information related to tertiary technologies presented in the PRAP. Ballasted flocculation technology provides the ability to achieve the lowest level of phosphorus removal. The Minister s Order also requested that costs be considered. Actiflo is also the most cost effective, considered both from a capital cost perspective, even with the factors set out above that, in my view, unnecessarily inflate the capital cost of all options. Actiflo is also the most cost effective from a lifecycle perspective, when operated seasonally. The evaluation of costs and phosphorus removal effectiveness is summarized in Tables 6 and 7. The PRAP Report offers two other assessment criteria that merit discussion, carbon footprint, and $/ kg of phosphorus removed. Carbon Footprint is not a criteria that the Minister asked to be considered, but it is one that the Regions felt important to include. The PRAP Report indicates that Carbon Footprint is essentially equivalent for all but membrane filtration, which shows a higher energy use than the other three options. Overall, the energy use required to operate any of the four options at a tertiary level is a very small percentage estimated at 3-7% - of the overall power use, and carbon footprint, of the WPCP itself. This very small 3-7% increase in energy use must be weighed against the environmental benefit of reducing the WPCP s effluent phosphorus by % if tertiary facilities are constructed. SUMMARY OF TERTIARY TREATMENT EVALUATIONS A summary of the most important tertiary evaluation criteria is included in Tables 6 and 7. Other evaluation criteria is believed to be secondary in nature. 18

20 Table 6: Assessment of Tertiary Treatment Options based a Primary Evaluation Criteria Factor Ballasted Flocculation Cloth Media Filtration Phosphorus Removal Effectiveness (concentrations are representative of typical tertiary effluent quality only) SRP: ~0.01 mg/l TP: mg/l Lowest effluent SRP option Lowest effluent TP option (with membranes) SRP: mg/l TP: mg/l Deep Bed Filtration SRP: mg/l TP: mg/l Membrane Filtration SRP: mg/l TP: ~0.05 mg/l Lowest effluent TP option (with ballasted flocculation) NPV Lifecycle Costs $289 M (yearround operation) $218 M (seasonal operation) Lowest NPV lifecycle cost option if operated seasonally $252 M (yearround operation) $226 M (seasonal operation) Lowest NPV lifecycle cost option if operated annually $320 M (yearround operation) $599 M (yearround operation) Source: Final PRAP Report, Table 7-13 (partial) Table 7: Summary of Potential annual Average Effluent Loadings with Tertiary Treatment Parameter Ballasted Flocculation Cloth Media Filtration Deep Bed Filtration Membrane Filtration TP mg/l 0.04 to to to 0.1 ~ 0.05 TP kg/d 25 to to to to 35 SRP mg/l to to to 0.04 SRP kg/d 7 to 8 20 to to to 25 Source: Final PRAP Report, Table

21 The information presented in tables 6 and 7 shows that ballasted flocculation technology, operated on a seasonal basis provides the least cost and lowest effluent TP and SRP concentrations. PRAP SECTION 8: COMPARISON OF SECONDARY AND TERTIARY TREATMENT OPTIONS Section 8 of the PRAP Report treats secondary treatment optimization as an alternative to tertiary treatment. This is not responsive to the Minister s Order. The Minister s Order was very clear. The Regions were asked to identify an option that will result in the lowest achievable level of total phosphorus in the effluent. That option is Actiflo (ballasted flocculation). Amongst those options that will result in the lowest achievable level, it is reasonable to then compare costs and operating implications. Section 7 of the PRAP Report made clear that in technical terms, all four technologies studied were options were reliable, constructible, and equivalent in terms of future proofing and operating and maintenance requirements. (In fact on the latter point, Actiflo had the unique benefit of not requiring a change in filter media). It is not reasonable to compare the costs of secondary optimization, which does not result in the lowest achievable level of total phosphorus in effluent, with tertiary treatment. To do so is to compare an option that does not achieve the stated goal, with one that does. Secondary optimization costs less because it does not achieve the stated goal of resulting in the lowest achievable level of total phosphorus in effluent. The magnitude of the difference is instructive. Tertiary treatment will result in SRP that is 5-10% of the SRP that would be provided by secondary optimization summarized as follows: Secondary treatment optimization is expected to result in effluent TP = mg/l and effluent SRP = mg/l. Tertiary treatment with Actiflo (ballasted flocculation) is expected to result in effluent TP = mg/l and effluent SRP = 0.01 mg/l. Section 8 of the PRAP Report fails to provide a true picture of the results of the PRAP to the Minister. The Minister s Order asked, very simply, for information about effluent phosphorus loadings to the lake under three conditions: historical phosphorus loadings based on past 5 years, MOECC directive item 2a phosphorus loadings that are estimated based on optimization of plant operations (i.e. secondary optimization), MOECC item 2b Phosphorus loadings that would result in the lowest achievable level of total phosphorus (i.e.: ballasted flocculation based tertiary treatment), MOECC item 2e. This information is presented in a concise form in table 8. 20

22 Table 8: Summary of Historical, Estimated Secondary Optimization and Tertiary Effluent Phosphorus Loadings (Kg/d) Based on Secondary Optimization (2) 2041 Based on Tertiary Treatment (3) Month (1) TP SRP TP SRP TP SRP TP SRP TP SRP TP SRP TP SRP April May June July August TP Average SRP Average (1) Months indicate Cladophora growth window Source: PRAP Technical Memorandum No. 1, Tab 62 (2) Based on secondary optimization effluent TP = 0.45 mg/l and SRP = 0.20 mg/l (3) Based on ballasted flocculation effluent TP = 0.05 mg/l and SRP = 0.01 mg/l PRAP SECTION 9: STUDY CONCLUSIONS This section presents study conclusions and discussed them in the order presented in the MOECC directive. The Town s review of each element is described herein: Data from the past five years on phosphorus concentrations and loading (item 2a). The PRAP Report adequately addresses this issue. A desktop study of optimization of plant operations to reduce phosphorus in the WPCP effluent (item 2b). The PRAP Report partially answers this item as a computer model was prepared to predict results of secondary optimization. The model was subsequently found to be invalid as field testing identified negative impacts on the secondary biological treatment process had phosphorus been removed via chemical addition to levels predicted by the computer model. It is clear based on the results of field testing that the WPCP cannot hit.35 mg/l without tertiary treatment. A study of new methods that could be employed to reduce phosphorus in the WPCP effluent (item 2c). 21

23 The PRAP Report adequately addresses this issue. Based on a and c above, considerations of options to reduce total phosphorus in the WPCP effluent including an indication of how phosphorus and loadings would be impacted by each option (item 2d). The PRAP Report adequately addresses this issue A determination of an option that will result in the lowest achievable level of total phosphorus levels in the effluent, including an assessment of the operating implications of, and the modifications and costs required to achieve such reductions (item 2e). The PRAP does present an evaluation of four technical options for tertiary treatment. However, the PRAP Report provides comparative costs for options that do not result in the lowest achievable level of total phosphorus levels in the effluent, in particular secondary optimization, which is not responsive to the Minister s Order. Ultimately, the PRAP Report does not select an option that results in the lowest achievable level of total phosphorus levels in the effluent, as the Minister directed. On this basis, the PRAP Report is non-compliant with item 2(e) of the Minister s Order. Table 8 shows that effluent TP and SRP loads discharged during the cladaphora window. As the WPCP s effluent flow is estimate to nearly double by 2041, the effluent TP and SRP loads are shown to increase from by a factor of 2.3 for TP and 2.0 for SRP when compared to 2014 (computer model validation year) if secondary optimization is implemented. Comparatively, if tertiary treatment is implemented, TP and SRP effluent loads are estimated to decrease by 75% for TP and 90% for SRP when compared to A strategy to reduce the amount of SRP in the WPCP effluent in the short, medium and long term including a method for determining how to quantify SRP reductions, and a description of methods to be used to measure the reductions (item 2f). The PRAP Report presents a short term strategy of secondary optimization that will help control the increase of phosphorus discharges in the short term (0-5 years), but will not decrease phosphorus discharges when compared to the baseline year of The PRAP Report does not offer any strategy for phosphorus reduction when compared to the baseline year of 2014, and therefore fails to comply with item 2(f) of the Minister s Order. If the Regions rely on nothing more than secondary optimization over the short, medium and long term, SRP will not be reduced over the planning period. Table 8 and Figures 1 and 2 show that effluent TP and SRP loads discharged during the cladaphora window. As the WPCP s effluent flow is estimate to nearly double by 2041, Table 8 and figures 1 and 2 also shows the estimated TP and SRP loads to the lake (kg/d) based on secondary optimization and tertiary treatment. Figures 1 and 2 shows a timeline for estimated effluent TP and SRP loads to the lake as flows increase over the planning period. The figures show the impact of three alternatives that were 22

24 evaluated in the PRAP (continued operation with current phosphorus removal practices, secondary optimization and tertiary treatment). It is clear that only tertiary treatment will result in a reduction in SRP loadings to the lake. Identification of the seasonal window of nuisance Cladophora algae growth and how total phosphorus in effluent may be further reduced during this time (item 2g). The PRAP Report adequately addresses this issue. Tertiary treatment can be limited to the Cladophora growth window and carried out for 4.5 months during the year, with less stringent secondary optimization limits applicable for the balance of the year. The Environmental Compliance Approval for the WPCP would have to be modified accordingly. A determination of the feasibility of achieving a permanent (or ongoing) annual average concentration of 0.35 mg/l of total phosphorus in effluent, as well as a total phosphorus load of 190 kg/d based on an annual average (item 2h). The PRAP Report makes clear, based on the results of the field study, that the WPCP cannot achieve.35 mg/l without tertiary treatment. 23

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