technical memorandum tm2 - durham

Baseline Scenario

F in a l

Lake Ontario Model Calibration and Baseline Scenario (Revised)

Prepared for

Regions of York and Durham

March 2013 (1st draft: June 2012, 2nd

Prepared by

draft: January 2013)

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Contents

1. Background and Purpose .................................................................................................. 1-1

2. Overview of Lake-wide Processes ................................................................................... 2-1 2.1 Background ............................................................................................................. 2-1 2.2 Near-shore environment ....................................................................................... 2-2 2.3 Phosphorus Loadings from Tributaries .............................................................. 2-3 2.4 Phosphorus Loadings from the Duffin Creek WPCP ....................................... 2-3

3. Effluent and Mixing Zone Requirements ...................................................................... 3-1 3.1 Provincial Water Quality Objectives ................................................................... 3-1 3.2 Near Field Zone Requirements............................................................................. 3-2 3.3 Far Field Effluent and Dilution Requirements ................................................... 3-2

4. CORMIX Model and Near Field Analysis ..................................................................... 4-1 4.1 Key Input Parameters ............................................................................................ 4-1

4.1.1 Ambient Lake Currents ............................................................................ 4-1 4.1.2 Existing Outfall Diffuser .......................................................................... 4-3 4.1.3 Effluent flow and Port Opening Size ...................................................... 4-3 4.1.4 Summary of Input Parameters ................................................................ 4-3

4.2 Results ...................................................................................................................... 4-5

5. MIKE-3 Model Set-Up ....................................................................................................... 5-1 5.1 Model History and Data Use ................................................................................ 5-1 5.2 Model Parameters................................................................................................... 5-1 5.3 Model Set-Up under Lake Ontario Ambient Conditions ................................. 5-4

6. MIKE-3 Model Calibration ............................................................................................... 6-1

7. Model Correlation to TRCA Data ................................................................................... 7-1 7.1 Nearshore Water Quality Monitoring Data ........................................................ 7-1 7.2 Model Inputs ........................................................................................................... 7-2 7.3 Comparison of Results ........................................................................................... 7-1

8. Baseline Modelling – 520 ML/d ....................................................................................... 8-3 8.1 Existing Outfall ....................................................................................................... 8-3 8.2 Effluent Certificate of Approval Requirements ................................................. 8-3 8.3 Provincial Water Quality Objectives ................................................................... 8-4 8.4 Receiving Water Characterization ....................................................................... 8-4 8.5 Total Phosphorus in Lake Ontario under the 520 ML/d Baseline Scenario .. 8-8 8.6 Un-Ionized Ammonia Levels in Lake under 520 ML/d Baseline Scenario . 8-10 8.7 Impact of Pickering NGS ..................................................................................... 8-17

9. Summary and Conclusions ............................................................................................... 9-1 9.1 Summary of Results ............................................................................................... 9-1

9.1.1 CORMIX MODEL: Near-Field Analysis ................................................ 9-1 9.1.2 MIKE 3 MODEL: Far-Field Analysis ...................................................... 9-1

0BBACKGROUND AND PURPOSE

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10. References ......................................................................................................................... 10-2

Figures Figure 2-1 Yearly Total Phosphorous Loading from the Duffin Creek WPCP from 2004 to 2011 .................................................................................................................................. 2-4 Figure 4-1 ADCP locations ..................................................................................................... 4-2 Figure 4-2 Plan View 520 ML/d – Coordinate System Used By CORMIX ..................... 4-5 Figure 5-1 Bathymetry of Lake Ontario (2430 GRID) ......................................................... 5-5 Figure 5-2 Bathymetry of the Duffin Creek WPCP Study Area (90 m Fine resolution Grid) .................................................................................................................................. 5-6 Figure 6-1 Comparison of Modelled Lake Current SPEED with OPG – ADCP Measurements .................................................................................................................................. 6-3 Figure 6-2 Comparison of Modelled Lake Current Direction with OPG-ADCP Measurements .................................................................................................................................. 6-4 Figure 6-3 NWRI Current Speed Comparisons – 5 m Depth - 2007 ................................. 6-6 Figure 6-4 NWRI Current Direction Comparisons – 5 m Depth - 2007 ........................... 6-7 Figure 6-5 MOE Offshore ADCP Comparisons – 2007 ....................................................... 6-9 Figure 6-6 MOE Offshore ADCP Comparisons - 2007 ..................................................... 6-10 Figure 6-7 MOE Nearshore ADCP Current Speed Comparisons - 2007 ........................ 6-12 Figure 6-8 MOE Nearshore ADCP CurrentT Direction Comparisons - 2007................ 6-13 Figure 6-9 Comparison of Model Tempertaure Predictions vs OPG Temperature Data ... ................................................................................................................................ 6-15 Figure 6-10 Comparison of Model Temperature Predictions vs NWRI Temperature Data 6-16 Figure 6-11 Comparison of Model Temperature Predictions vs MOE Offshore Temperature Data .......................................................................................................................... 6-17 Figure 6-12 Comparison of Model Temperature Predictions vs MOE Nearshore Temperature Data .......................................................................................................................... 6-18 Figure 7-1 Transect Locations for Water Quality Survey - Station Identification Numbers Start at Shoreline and Increase Offshore ..................................................................... 7-3 Figure 7-2 Concentration isopleths - averages of TRCA transect data for 2008 ............. 7-2 Figure 7-3 Concentration isopleths – average of 2008 simulation results from MIKE3. 7-2 Figure 8-1 75th Percentile TP by Station ............................................................................... 8-6 Figure 8-2 Howell Presentation - TP Offshore Lake Ontario ............................................ 8-7 Figure 8-3 TP mixing zone as defined by the 90th 8-8 percentile ............................................. Figure 8-4 Average Surface TP Levels ................................................................................ 8-10 Figure 8-5 MOE Ammonia Survey ...................................................................................... 8-11 Figure 8-6 Mixing zone for UIA is non-existent as defined by the 90th

8-13 percentile –

Winter Period ................................................................................................................................ Figure 8-7 Mixing zone for UIA as defined by the 90th 8-13 percentile - Summer Period .. Figure 8-8 Average Surface UIA Levels – Winter Period ................................................. 8-14 Figure 8-9 Average Surface UIA Levels - Summer Period ............................................. 8-14 Figure 8-10 Ajax Intake Ammonia Time Series ................................................................. 8-16


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Figure 8-11 Compass Rose representation of Current Speeds (in m/s) and Directions – NWRI ADCP ................................................................................................................................. 8-17 Figure 8-12 Circulation patterns as predicted by the model with the Pickering NGS inputs ................................................................................................................................. 8-19 Figure 8-13 Circulation patterns as predicted by the model without the Pickering NGS inputs ................................................................................................................................. 8-19 Figure 8-14 Average concentration isopleths at 520 MLD with the Pickering NGS ....... 8-20 Figure 8-15 Average concentration isopleths at 520 MLD without the Pickering NGS . 8-20 Tables

Table 2-1 Change in Total Phosphorus Effluent Limits Before and After the Stage 3 Expansion ................................................................................................................................... 2-3 Table 3-1 Provincial Water Quality Objectives (PWQO) for key parameters ................ 3-1 Table 4-1 25th 4-3 Percentile Lake Current Speeds for OPG Station ...................................... Table 4-2 25th 4-3 Percentile Lake Current Speeds for additional Stations ........................... Table 4-3 Key CORMIX Model Input Variables ................................................................. 4-4 Table 4-4 Key CORMIX Model Input Parameters ............................................................. 4-4 Table 4-5 Dilution ratio and CORMIX predictions at different flow rates – Outfall EA ... ................................................................................................................................... 4-5 Table 5-1 Model input parameters used in MIKE-3 simulation software ...................... 5-2 Table 5-2 Lake levels used for MIKE-3 model simulation as compared to long term averages ................................................................................................................................... 5-3 Table 5-3 MIKE-3 Model Characteristics – 2006 and 2011 ............................................... 5-3 Table 6-1 Basis for evaluating model calibration using the variance between simulated and observed current velocities (F-norm) ..................................................................................... 6-2 Table 6-2 NWRI F-norm DATA – 2007 .......................................................................................... 6-8 Table 6-3 MOE Offshore F-norm Data – 2007 ..................................................................... 6-8 Table 6-4 MOE Nearshore F-norm DATA - 2007 ............................................................. 6-11 Table 7-1 Tributary Loadings Included in the MIKE-3 Model ......................................... 7-2 Table 8-1 Spatial and Temporal Extent of Surface TP Plume ........................................... 8-9 Table 8-2 Spatial and Temporal Extent of Surface UIA Plume ...................................... 8-15

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1. Background and Purpose

For effluent discharges, the Ministry of Environment (MOE) has guidelines for the near field effluent mixing and far field effluent dilution requirements. In 2006, computer modelling to assess near field effluent mixing and plume dispersion was completed as part of the Schedule C Class Environmental Assessment (Class EA) for the Duffin Creek WPCP Stage 3 expansion. The Expansion EA identified the preferred solution for expanding treatment capacity at the Duffin Creek WPCP to 630 ML/d. This expansion is referred to as the Stage 3 expansion, as it is the third phase of plant development. It includes expansion and enhancement of treatment processes at the Duffin Creek WPCP to provide 630 ML/d capacity, while also providing nitrification and phosphorus removal capacity. This additional capacity is key to the plant meeting its Certificate of Approval mass loading limit of 311 kg/d for TP at both current and future flows. The expansion also provides for expansion and upgrade of the sludge treatment facilities.

The CORMIX model was used to estimate the near field mixing ratio. The underlying model assumption was to use calm lake conditions. It showed that the Ministry of the Environment (MOE) mixing guideline of 20:1 for the near field zone will be met by the existing outfall until the flows reach an average day flow of 560 ML/d. However, as a condition of approval for the Stage 3 Expansion, MOE required that the flow from the outfall should not exceed 520 ML/d.

In 2006, outfall discharge modelling was also completed to assess far field dilution and to see whether the treated discharge, after initial dilution and dispersion, meets Provincial Water Quality Objectives (PWQOs) for total phosphorus (TP) and un-ionized ammonia (UIA).

The MIKE-3 hydrodynamic and water quality model, a three-dimensional model, was used to delineate the outfall plume and identify the mixing zones for TP and UIA. The modelling results helped to identify the preferred expansion alternative; in particular the need to provide additional phosphorus and ammonia removal as part of the plant expansion and establish stricter TP and ammonia limits for the expanded plant. These stricter TP and ammonia limits are now part of the existing CofA requirements for the plant.

Since the modelling work carried out in 2006, MOE has approved a new operating limit of 520 ML/d for the existing outfall and additional background lake data has become available. As a result the MIKE-3 model has been updated and re-calibrated, and a new baseline scenario of 520 ML/d flow has been run.

The purpose of this report is to describe the CORMIX and MIKE-3 models. In particular, the report details the results of re-calibration of the MIKE-3 model using updated water quality and Acoustic Doppler Current Profiler (ADCP) data. In addition to updating and calibrating the models, results from the baseline scenario run (520 ML/d) are also presented to provide a basis for future comparisons.

Finally, it should be noted that plant flows at 520 and 630 ML/d referred to in this report refer to average dry weather flows (ADWF). Only ADWF have been modeled in either


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CORMIX or MIKE-3 (i.e. wet weather flows are not considered in these analyses). However, peak wet weather flows (PWWF) have been considered in determining the hydraulic capacity of the diffuser.


2. Overview of Lake-wide Processes

2.1 Background During the period of the 1960s to the early 1980s, eutrophication as a result of growing populations in the Great Lakes watershed was significantly deteriorating the water quality in Lake Ontario. Phosphorus concentrations, generally accepted to be the limiting nutrient for algal growth in Lake Ontario, were measured as high as 30 ug/L in the offshore in the 1970s (Stevens and Neilson, 1987). Growth of phytoplankton in the offshore and Cladophora in the near-shore were creating problems such as zones of oxygen depletion (due to algal decay), toxins associated with cyanobacteria blooms and fouling of beaches and clogging of cooling water intakes. In response to this problem, the Great Lakes Water Quality Agreement was signed in 1972 which led to specific nutrient loading targets being identified in 1978 and again in 1987. The implementation of this agreement resulted in spending on the order of $9B, primarily for the construction and upgrade of wastewater treatment plants. Improvements in lake water quality as a result of these measures were almost immediately noticed and TP concentrations in the offshore dramatically declined in the 1970s and 80s to less than 20 ug/L. Reductions in Cladophora growth in the lower Lake Ontario were documented and P-management strategies implemented through the GLWQA were deemed successful (Painter and Kamaitis, 1987).

Today concentrations of TP in the offshore of Lake Ontario are below the water quality objective of 10 ug/L and, as of 2010, continue to decline (Environment Canada, no date). While this decline is positive from the point of view of controlling eutrophication, it is seen as having negative consequences for the ecosystem and fisheries. Phosphorus concentrations are necessary to sustain growth of algae and zooplankton and there is concern that continuing decreases in levels may result in collapse of the fishery (Thornburn, 2011; Holleck, no date).

Despite achieving the reduced phosphorus targets in the offshore waters of Lake Ontario, a resurgence of Cladophora growth has attracted attention, particularly in the last decade. This resurgence coincided with the introduction to Lake Ontario of Zebra and Quagga mussels (Dreissenids), invasive species which are thought to play a critical role in promoting Cladophora growth by:

• reducing turbidity in the water thereby allowing light to penetrate to greater depths,

• increasing the supply of bioavailable phosphorus by converting particulate phosphorus to soluble reactive phosphorus, and

• colonizing sandy areas thereby providing hard surfaces for Cladophora attachment in areas that were previously unsuitable.

It is difficult to understate the role of the dreissenids infestation in “re-engineering” the ecosystem of Lake Ontario since the 1990s. Mussel beds now cover the entire lake bottom in many areas of the lake and light penetration depths have increased from around 5 meters to

1BOVERVIEW OF LAKE-WIDE PROCESSES


as much as 20 meters (Howell, 2012). As a result, the near-shore environment has dramatically changed since the years when the original Great Lakes Water Quality Agreement was developed and the Cladophora problem has become worse despite exceeding reduced phosphorus targets in the offshore environment. Recent and ongoing research is therefore focusing on the dynamics and phosphorus in the nearshore environment (Howell, 2012, Auer, 2011, Thorburn, 2001).

2.2 Near-shore environment The near-shore environment typically corresponds to offshore depths in the range of 10 to 20 m and is loosely defined as the zone in which the lake interacts strongly with the lakebed, shoreline, tributaries and people (Howell, 2012). In Lake Ontario, colonization by dreissenid mussel beds is widespread throughout the near-shore environment and growth of Cladophora seems to only be limited by the availability of light, hard substrate for attachment and phosphorus. Given the relationship between phosphorus loadings and human activity, greater production of Cladophora might be expected to occur in areas of high population density in the vicinity of point source loadings. Cladophora appears to be a lake-wide problem, however, and there is no indication that growth is more abundant in these areas. A possible reason for this is that near-shore phosphorus concentrations are influenced by an array of factors including:

• exchanges with the offshore environment,

• local discharges including tributary and point source loads (e.g. stormwater, wastewater treatment plants),

• interactions with the lakebed including wave-induced re-suspension of sediments (Howell, 2012) and release of soluble reactive phosphorus from Zebra mussel beds (Martin, 2010), and

• along-shore currents which transport phosphorus along the predominant west-east current that exists on the north shore of Lake Ontario (Leon, 2009).

Cladophora growth in the near-shore environment has been shown to be sensitive to soluble reactive phosphorus concentrations in the range of 1 to 2 ug/L (Tomlinson et al., 2011). As a result, a leading management strategy for controlling Cladophora growth might center on minimizing soluble reactive phosphorus loading to the near-shore zone. However, measurements in the offshore environment have been reported in the range of 1.4 to 2.5 ug/L with higher concentrations measured closer to shore (Auer, 2011). As a consequence, there is debate as to whether the ambient concentrations of soluble reactive phosphorus (both offshore and alongshore) lie within a range that is sensitive to load management. In addition, the role that Dreissenids play in converting particulate to soluble phosphorus must be taken in account. For example, higher concentrations of soluble reactive phosphorus have been measured above mussel-beds relative to other non-colonized substrate. This suggests that soluble reactive phosphorus released by Dreissenids could be more important than external inputs (Martin, 2010). Ambient conditions, exchanges with the mussel beds and transport of phosphorus alongshore are key areas of ongoing research into the causes for Cladophora growth.



2.3 Phosphorus Loadings from Tributaries Phosphorus loading to Lake Ontario comes from many sources with the Niagara River being the largest single contributor (more than 50%) and is typically considered to be the main driver of phosphorus concentrations in the offshore. Tributaries such as streams and rivers around the lake contribute around 30% of the total lake load and wastewater treatment plants around 10% (Makarewicz et al., 2012). These loads are considered important drivers of phosphorus concentrations in the near-shore environment. Tributary loads, in particular, have the potential to influence the near-shore environment as they tend to discharge right at the shoreline. Moreover, modelling studies have shown that along-shore currents are more significant than cross-shore currents so that phosphorus from tributaries is likely to have a higher retention time in the near-shore environment, thereby creating more impacts on water quality.

It should be noted, however, that there can be significant uncertainty related to the calculation of tributary loadings. While flow rates from streams and rivers can be recorded on a continuous basis, concentration data from tributaries tend to be sparse and often omit periods of high flow due to snowmelt or rainfall events. This creates biases in the data sets which could lead to an underestimation of phosphorus loading calculation (Bowen and Booty, 2012). More work is currently underway by TRCA and others to further assess a more accurate prediction of phosphorous loading due to surface runoff from streams and local storm sewer systems.

2.4 Phosphorus Loadings from the Duffin Creek WPCP During the Stage 3 Expansion, new effluent limits were established through consultation with MOE and other stakeholders based on the receiving water impact assessment. With the commissioning of the Stage 3 Expansion in the fall of 2009, the new effluent limits came into effect. The new effluent limits for total phosphorus are detailed in Table 2-1. These effluent limits are in place for average day flows up to and 630MLD at which time a separate Class EA will be conducted for flows above 630MLD.

TABLE 2-1 Change in Total Phosphorus Effluent Limits Before and After the Stage 3 Expansion

Parameter Effluent Limit before Stage 3 Expansion

Effluent Limit after Stage 3 Expansion

Total Phosphorus Concentration

1.0 mg/L 0.8 mg/L

Total Phosphorus Loading 420 kg/day 311 kg/day

The new effluent limits have resulted in improved effluent water quality being discharged to the receiving water. Figure 2-1 illustrates the actual phosphorous loading to the receiving



water from 2004 to 2011. The total phosphorus loadings decreased with the commissioning of the Stage 3 Expansion in 2009.

FIGURE 2-1 Yearly Total Phosphorous Loading from the Duffin Creek WPCP from 2004 to 2011


3. Effluent and Mixing Zone Requirements

The Ministry of Environment (MOE) requires that lake ambient conditions and effluent discharges be evaluated through lake modelling to meet surface water quality objectives and for deriving effluent requirements. The water quality objectives are referred to as Provincial Water Quality Objectives (PWQO) and are discussed below.

A mixing zone around the diffuser is necessary to ensure adequate dilution. According to Policy 5 of the MOE’s Water Management1

A mixing zone is defined as an area of water contiguous to a point source or definable non-point source where the water quality does not comply with one

or more of the Provincial Water Quality Objectives.

, a mixing zone should be designed to be as small as possible and not interfere with beneficial uses such as water supply intakes, other effluent discharges, bathing beaches, fish spawning areas, or fish migration routes. Water Management provides the following definition of a mixing zone:

The basic mixing zone elements are divided into “near field” modelling and “far field” modelling. Each modelling element is discussed below.

3.1 Provincial Water Quality Objectives The PWQO are criteria which serve as chemical and physical surrogates of healthy populations of aquatic biota. They represent a satisfactory level of quality for surface waters. The PWQO for Total phosphorous (TP), un-ionized ammonia (UIA), and E. coli are presented in Table 3-1.

TABLE 3-1 Provincial Water Quality Objectives (PWQO) for key parameters Parameter Concentration Limit Un-ionized ammonia (UIA) 20 ug/L 1 Total ammonia nitrogen (TAN) 500 ug/L 2 Total phosphorus (TP) 20 ug/L 1 E. coli 100 E. coli per 100 mL 1 1Provincial Water Quality Objective (PWQO) 2Great Lakes Water Quality Agreement

Total Phosphorus

To avoid nuisance concentrations of algae in lakes, average total phosphorus concentrations for the ice-free period should not exceed 20 ug/L1. The PWQO for TP is intended to reduce the occurrence of algal blooms in Lake Ontario for which phosphorous is assumed to be the limiting nutrient. This can be explained in terms of the Redfield ratio for Lake Ontario which, based on measured ambient concentrations of soluble reactive phosphorus SRP less than 0.01

1 Water Management Policies, Guidelines, Provincial Water Quality Objectives, Ministry of Environment and Energy, July 1994.


mg P/L and nitrite+nitrate of around 0.4 mg N/L, is greater than 40:1. Generally, it is assumed that phosphorus limited environments are characterized by Redfield ratios of greater than 16:1. It should be noted, however, that the occurrence of algal blooms is very complex and involves other factors such as the bio-availability of the phosphorous, relative concentrations of other nutrients (e.g. dissolved inorganic nitrogen, DIN), water clarity and water temperature.

E. coli

The PWQO for bacterial quality maintains suitable conditions for recreational purposes and for the protection of human health, and is based on maintaining less than 100 E. coli per 100 mL sample. Disinfection of all flows from the Duffin Creek WPCP ensures that discharged effluent is well below the PWQO for E. coli: the geometric mean for 2011 was 7 E. coli per 100 mL. For this reason, simulation results for E. coli in the effluent plume are not presented in this report.

Ammonia

The UIA PWQO is for the protection of aquatic life and has been set at 20 ug/L to avoid chronic effects and 100 ug/L for acute toxicity. The 20:1 initial mixing ratio provides sufficient dilution to meet PWQO for UIA at the edge of the near field mixing. A limit for Total Ammonia Nitrogen at drinking water intakes has been set at 500 ug/L by the International Joint Commission.

3.2 Near Field Zone Requirements The “near field” mixing zone refers to the portion of the effluent plume that extends from the diffuser outlets (ports) to the location where the discharged plume has effectively completed its initial mixing with the ambient lake water, as caused by buoyancy and momentum differences.

The CORMIX model has been used to estimate the dilution ratio in the near field mixing zone. This model is specifically designed to assist in the prediction of plume mixing behavior from various types of outfall configurations, under various lake and effluent conditions.

In the event that PWQO cannot be met in the near field mixing zone, a far field model is used to delineate the mixing zone required to meet PWQO and evaluate whether this zone interferes with “beneficial uses”.

3.3 Far Field Effluent and Dilution Requirements After dilution due to initial mixing is established, the next procedure is to determine dilution of the effluent plume in the far-field zone. Dilution beyond the initial near-field zone is usually associated with ambient lake processes (offshore currents, dispersion, etc.) and tends to occur at a greatly reduced rate in comparison to the initial mixing within the near field. Modelling the far-field effluent plume and associated dilution is accomplished using a whole lake model, such as MIKE- 3, wherein the main purpose is to determine the size of the mixing zone. In particular, the plumes’ potential effects on Lake water quality and surrounding water uses (e.g. drinking water intakes, near shore recreation, etc) are identified. The MIKE -3 model was calibrated to represent realistic simulations of the lake conditions. It was then used to simulate the plume with respect to PWQO for TP and UIA over the critical April to November period. The extent of the plume was then defined based on both average concentrations and the 90th percentile isopleths. A 90th percentile criterion was chosen because it is conservative and screens out


extreme events which have no impact on the environment. For example, nuisance species such as Cladophora have a doubling time on the order of two days. As a result, spikes in TP levels that take place over a shorter time period do not provide the conditions for growth.

Although under most conditions this is not an issue, a further concern that could be raised is meeting the total ammonia drinking water standard of 500 ug/L at the location of the Ajax WSP intake. To address this, the MIKE-3 model was also used to simulate total ammonia concentrations at the Ajax WSP intake.


4. CORMIX Model and Near Field Analysis

CORMIX is a mixing zone model for assessment of near field dilution and mixing zones resulting from continuous point source discharges such as the Duffin WPCP outfall. Diffuser performance is assessed using the average annual daily flow by reporting the initial dilution at the edge of the near field region where momentum associated with the effluent jet has fully dissipated. The User’s Guide for CORMIX states that predictions of dilutions and concentrations in the effluent plume are accurate to within +/- 50%. However, comparisons with field data suggest higher levels of accuracy are achieved with the CORMIX model (Abdel-Gawad, 1985; McCorquodale, 2007). The CORMIX model is a standard tool approved by the MOE for calculating initial dilution in the near-field region and, as such, gives a good basis of comparison for performance of different outfall alternatives. The subsection below describes the selection of key input parameters.

4.1 Key Input Parameters The basic characteristics used in the CORMIX model relate to the location and configuration of the outfall diffuser, effluent flow, and the ambient lake conditions. New data collected since the Expansion EA in 2006 was used to update and calibrate the CORMIX model. A description of those changes is summarized below.

4.1.1 Ambient Lake Currents Lake currents are measured with Acoustic Doppler Current Profilers (ADCP). A number of ADCPs are located in the vicinity of the outfall as depicted in Figure 4-1.

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FIGURE 4-1 ADCP locations

The OPG ADCP operates year round and has been functional since 2001. Current speed data for the OPG station is in Table 4-1. The other meters were deployed in 2007 but only for portions of the year. Current speed data for the other stations is in Table 4-2. The OPG location is considered to characterize the required bottom currents most accurately, due to its proximity to and similar depth as outfall diffuser. Accordingly, OPG ADCP data from 2001-2010 was used in the CORMIX model. For lake currents, the MOE specifies the use of the 25th percentile for quantifying ambient conditions i.e. the lake current below which 25 percent of the measured current data may be found. In accordance, the OPG ADCP data were partitioned by season and the yearly data were enumerated to determine the 25th percentile. For current speeds, using the 25th percentile results in more conservative predictions of dilution rates than would be obtained using average speeds (the 50th percentile). This follows the general principle established in Procedure B-1-5 in which the 75th percentile is specified for ambient water quality constituents such as temperature and pH3

.

It is well known that during the late fall to early spring period, higher current speeds are observed due to higher energy storms passing through the lake. Recorded lake current speeds from 2001- 2010 are presented in Table 4.1 according to season. The current speed used for the CORMIX model was the average for the spring – summer season which was 0.044 m/s. The spring – summer season is considered the critical period for calculating mixing in the near field zone because lower current speeds contribute to less mixing energy.

3 Deriving Receiving-Water Based, Point-Source Effluent Requirements for Ontario Waters, Ministry of Environment and Energy, July 1994.


TABLE 4-1 25th

Year/Season Percentile Lake Current Speeds for OPG Station

Jan – Mar (m/s)

Apr- Jun (m/s)

Jul – Sep (m/s)

Oct – Dec (m/s)

2001 0.081 0.034 0.041 0.068 2002 0.109 0.05 0.0407 0.075 2003 0.071 0.045 0.044 n/a 2004 n/a n/a 0.055 0.058 2005 0.051 0.039 0.067 n/a 2006 0.057 0.058 0.057 n/a 2007 n/a n/a n/a 0.072 2008 0.092 0.057 0.011 0.107 2009 0.06 0.031 0.039 0.05 2010 0.047 0.038 0.048 0.06 Average 0.065 0.044 0.044 0.07

TABLE 4-2 25th

Year Percentile Lake Current Speeds for additional Stations

Location 25th Start Time

Percentile (m/s)

End Time

2007 MOE Offshore 0.036 Apr 3 Nov 26

2007 Moe Nearshore 0.023 Apr 3 Nov 26

2007 NWRI 0.041 Apr 10 Jul 9

2007 NWRI 0.124 Jul 12 Oct 23

4.1.2 Existing Outfall Diffuser The existing outfall extends 1.1 kilometers into the lake with a 183m diffuser that has 63 evenly spaced ports. The ports are arranged in a staged diffuser configuration, staggered at an angle of 22.5˚ to the centre line to allow for maximum dispersion of the effluent. The existing configuration is consistent with the 2006 configuration and has not changed.

4.1.3 Effluent flow and Port Opening Size The diffuser port diameter and opening schedule is established based on the available head loss in the outfall at peak flow conditions. The CORMIX model was run using the port diameter to determine the initial dilution ratio at average day flow. In the Expansion EA, the port opening of 0.225m was used for an average day flow of 520MLD. In the Outfall EA, the baseline scenario is using the same port opening of 0.225m at 520MLD.

Based on preliminary findings, the hydraulic capacity of the outfall is approximately 2,000 ML/d, assuming a Hazen William C factor of 90, and all 63 ports fully open with a discharge diameter of 0.45m. Further hydraulic analysis will be performed during Phase 2 of the EA.

4.1.4 Summary of Input Parameters A number of key input variables and parameters for the CORMIX model have changed since the Expansion EA. These are detailed in Table 4-3 and 4-4.


TABLE 4-3 Key CORMIX Model Input Variables Model Input Variable 2006 (Expansion EA) 2011 (Outfall EA)

Source of Current Speed Data OPG ADCP station 2001 OPG ADCP station 2001-2010 Current Speed 4 cm/s (25th 4.4 cm/s (25 percentile of OPG

data from 2001) th

Average depth of diffuser

percentile of OPG data from 2001-2010)

9 m (based on low lake level) 10.2 m (based on average lake level which the best practice used on other outfall studies in Lake Ontario)

The parameters used in CORMIX are listed below.

TABLE 4-4 Key CORMIX Model Input Parameters Model parameter Value Description

Average depth of diffuser 10.2 m Based on average lake level and depth at mid point of the diffuser.

Diffuser distance offshore 914 m Physical characteristic of outfall

Port diameter 0.225 m @ 520 MLD Physical characteristic of outfall diffuser

Riser height 1.0 m Physical characteristic of outfall diffuser

Staged diffuser configuration perpendicular to current

Gamma = 90, Theta = 0, beta = 0, Sigma = 270

Physical orientation of diffuser ports

Number of ports 63 Physical characteristic of outfall diffuser

Port spacing 2.9 m (183 m length / 63)

Physical characteristic of outfall diffuser

Receiving water environment

Unbounded Physical characteristic of outfall environment

Density current Uniform Default assumption non-stratified conditions

Ambient Current Speed 0.044 m/s 25th

Wind Speed

percentiles for the spring – summer season

5 m/s Based on recommended CORMIX method

Bottom friction 0.035 Manning’s N Default assumption – relatively smooth bottom

Ambient water temperature 15 °C Average for spring / summer season

Effluent temperature as difference from ambient

+2 , +5, -2 °C The temperature difference was found to have no impact on the dilutions and initial plume behavior.

Effluent Flow 520 ML/d Effluent flow through diffuser


4.2 Results With the above input variables and parameters, the CORMIX model was run and the results are detailed in Table 4-5. At the baseline flow of 520 MLD, the CORMIX model predicted the dilution within the near field mixing zone (the mixing ratio) to be 22.8:1. As shown in Fig. 4-2, the distance offshore and downstream (east) for the near-field mixing zone was 413m and 45m respectively.

With a 22.8:1 mixing ratio calculated using the CORMIX software, the mixing zone for TP extends outside the near-field mixing zone. As such, a far-field analysis is required to further delineate the edge of the mixing zone. The MIKE-3 model is used for this purpose.

TABLE 4-5 Dilution ratio and CORMIX predictions at different flow rates – Outfall EA

Flow (MLD)

Mixing Ratio

X downstream (m)

Y Offshore (m)

Half-Width (m)

520 22.8 : 1 51 366 153

Figure 4-2 shows the coordinate system used by CORMIX.

FIGURE 4-2 Plan View 520 ML/d – Coordinate System Used By CORMIX

Edge of the Near Field Mixing Zone


5. MIKE-3 Model Set-Up

The DHI Software MIKE-3 platforms, a three-dimensional hydrodynamic and water quality model, was used to delineate the effluent plume as it extends outside of the near field mixing zone. This tool is used to assess whether the treated discharge, after initial mixing and subsequent dispersion, meets the PWQOs. The use of a three-dimensional model is critical to this task because Lake Ontario is thermally stratified during the summer months. This stratification should be accounted for in three dimensions to accurately model the currents in the near shore environment.

5.1 Model History and Data Use Historically this model has been use for last 15-20 years and is approved for use by the Ministry of Environment (MOE). It uses baseline data from the whole lake. Most recently, the model was calibrated during the preparation of the Schedule C Class Environmental Assessment for “Provision of Additional Capacity at the Duffin Creek Water Pollution Control Plant” (September 2006). The model calibration and the associated results were used were relied upon by the MOE to make project and approval related decisions.

The model has since been improved upon. It now uses a new refined grid of Lake Ontario with 90 m resolution, which allows the existing diffuser to be spread over two grids. This has resulted in an improved simulation of the effluent plume momentum and the advection-dispersion process in the far-field.

In addition to other data, the Region and TRCA and MOE monitoring results were also used to establish ambient water quality conditions. Newly available water quality and current data were used to refine the model input parameters. The calibration with new water quality data and the current data was successful; though, some locations had better model agreement than others. Generally, the model has better current predictions in the weakly stratified or non-stratified periods of the year. The temperature response of the model was good for the entire period of simulation.

5.2 Model Parameters The MIKE-3 model is based on the fully non-linear three dimensional representation of mass, momentum and energy fluid motion. The model has the additional capacity of nesting fine grid models inside coarse grids to allow detailed modelling of areas of interest. The non-hydrostatic (and non steady-state) version of the model was used as it provides the most accurate simulations for Lake Ontario.

Key model parameters used in the MIKE-3 model are presented in Table 5-1.

4BMIKE-3 MODEL SET-UP


TABLE 5-1 Model input parameters used in MIKE-3 simulation software Model input parameter

Value Description

Simulation engine

Non-hydrostatic Allows dynamic simulation of water quality over time including buoyancy forcing in vertical direction

Time step 30 s Maximum allowable time step that maintains Max Courant # below 6.5

Transport scheme

Quickest-Sharp Standard modelling practice in MIKE-3 for high correlations with observed data

Smagorinsky coefficient

0.4 (mixed k/e) Turbulence scheme used to determine dispersion rates. Default parameter in MIKE-3

Dispersion factors

0.1 horizontal, 0.001 vertical Default horizontal parameter in MIKE-3, vertical value from calibration trials

Wind stress coefficient

Variable function to account for lower coefficients at low wind speeds and higher coefficients at high wind speeds

Function calibrated to fit model to measured current speeds as per standard MIKE-3 modelling practice

Heat exchange coefficients

0.5, 0.9, 0.395, 0.571, -1, -75, 0.1, 1, as ordered

Default model parameters - solar A and B from calibration, daylight savings time and standard longitude for solar timing

Vertical resolution

40 layers at 2 m thickness Provides coverage to 80 m depth, assumes a single layer beneath

Bed roughness 0.05 Default value, sensitivity is low for this parameter

Advection-Dispersion factors

Default values using eddy viscosity relationship

Used in calculation of mixing

Since the completion of Class EA, the model was updated based on the following new information:

• A new refined grid of Lake Ontario of 90 m resolution.

• New current information used for model calibration: In 2007 three new Acoustic Doppler Current Profiler (ADCP) current meters were installed in the area; two by MOE and one by National Water Research Institution (NWRI). In the earlier modelling, current information was obtained from only one current meter installed by Ontario Power Generation (OPG).


• New Wind Field from the National Oceanic and Atmospheric Administration (NOAA) Mesascale Atmospheric model – other studies with City and CCIW have found that wind fields provide better accuracy than a single airport station.

• Higher vertical resolution – Other studies have shown better accuracy resulting from it.

• Used a more accurate transport-advection scheme in the model.

• New 90m grid allowed existing diffuser to be spread over two grid elements.

• Water quality results based on testing undertaken by the Regions and the TRCA for the years 2007, 2008 and 2009.

• Stricter effluent limits with respect to total phosphorus.

• Lake levels for the simulation were based on measured 2007 levels as shown in Table 4-2. (Lake levels for 2007 started out the year higher than the long term mean but by May the levels dropped to normal and then through the summer the levels dropped between 14 to 18 cm below average.)”

TABLE 5-2 Lake levels used for MIKE-3 model simulation as compared to long term averages Month J F M A M J J A S O N D

2007 74.98 74.97 74.85 75.01 75.05 74.98 74.86 74.71 74.56 74.42 74.31 74.32

Long Term Average 74.56 74.6 74.68 74.88 75.01 75.05 75 74.88 74.74 74.61 74.54 74.53

A summary of the changes in the modelling parameters since the 2006 Expansion EA are summarized in Table 5-3.

TABLE 5-3 MIKE-3 Model Characteristics – 2006 and 2011 Parameter/Assumption 2006 (Expansion EA) 2011 (Outfall EA)

Resolution for Nested Grid

135 m 90 m

Modelling Period April – Sep 2001 (6 months) April – November 2007 (8 months)

Current Data Based on data from 1 station Based on data from 4 stations

Ambient TP 0.01 mg/L 0.01 mg/L in the nearshore

0.007 mg/L in the offshore

Ambient Ammonia 0.0 mg/L 0.008 mg/L

Average flows

Effluent TP

560 ML/d

1 mg/L

520 ML/d

0.6 mg/L



Effluent Ammonia 10 mg/L Nov- Apr, 6 mg/L May-Oct

10 mg/L Nov- Apr, 6 mg/L May-Oct

Vertical resolution X layers at 4 m per layer. 40 layers at 2 m per layer

The updates made to the model as outlined in Table 5-2 have led to improved calibration to measured temperature and current velocity data.

5.3 Model Set-Up under Lake Ontario Ambient Conditions Bathymetry, the lake bottom elevations that exist across an area of interest, influences a lake’s assimilation capacity. The MIKE-3 Lake Ontario model is based on a 2,430 m coarse grid that extends across the whole lake. Within this coarse grid, nested grids of 810, 270 and 90 m are used to focus in on the area around the Duffin Creek outfall/diffuser. The bathymetry of the lake was obtained from the National Oceans and Atmospheric Administration (NOAA) project for Great Lakes Bathymetry, available on CD, Volume G2 (www.ngdc.noaa.gov/mgg/greatlakes/).

The location of the nested grids areas within the whole lake environment is presented in Figure 5-1. The 90 m fine grid around the outfall diffuser is presented in Figure 5-2. It should be noted that the model grid has been rotated so that a horizontal east-west shoreline is produced for the 90 m grid; this is a standard technique for modelling shoreline features.

http://www.ngdc.noaa.gov/mgg/greatlakes/�



FIGURE 5-1 Bathymetry of Lake Ontario (2430 GRID)



FIGURE 5-2 Bathymetry of the Duffin Creek WPCP Study Area (90 m Fine resolution Grid)



Other data used in the model included water quality, temperature, pH and currents. The use of this data is as follows:

• The existing background (or ambient) water quality is used to model the area of the plume in which PWQO are exceeded. The existing nearshore ambient water quality for Lake Ontario was determined using the Regions, TRCA and MOE monitoring data.

• Ambient temperature in the lake, and more specifically the difference with respect to the effluent temperature, impacts the buoyancy of the effluent plume and dispersion of the effluent plume once it is discharged.

• Lake currents speed and direction, will affect the rate of dispersion and direction of the effluent plume.

• Temperature, together with pH, determines the speciation of total ammonia nitrogen between the ionized (NH4+) and the toxic un-ionized forms (NH3

The model was initially simulated based on hourly wind speed and direction from Pearson Airport and then subsequently using data for the wind field across Lake Ontario as provided by NOAA, which proved more accurate. Additional meteorological data consisting of air temperature, relative humidity and cloudiness were also used to provide the thermodynamic forces responsible for heating and cooling of the lake water.

).

Daily water surface elevation data at Kingston were provided to the model to maintain observed water depths. Hydraulic flow (daily) from the Niagara River was applied at the mouth of the river. As such, the stage at Kingston and the flow from the Niagara River established the boundary conditions for the lake. In addition, to capture the effect of local inflows on the mixing zone, flows from Duffins Creek were accounted for in the model. Water temperatures from the Environment Canada buoy in Lake Erie augment the Niagara River flow data. The cooling water flow from the Pickering NGS was not included in the model because this cooling water discharge is confined to the very near-shore area and does not influence the area of interest around the Duffin Creek effluent outfall. Model calibrations results presented in section 6, which do not include the hydraulic and thermal impact from the NGS, show good calibration to data from the OPG ADCP and thus confirm that the Pickering NGS cooling water does not significantly impact the mixing behaviour in this region. Moreover, it is our opinion that the current operation and potential future decommissioning of the Pickering NGS would not impact the mixing behaviour of the effluent plume.

The model was setup to provide continuous simulations from April to November. This period is the most sensitive time for taste and odour problems at water treatment plants and is also the most productive period for aquatic growth. In addition, the continuous simulations cover the periods when low dilutions would occur due to slower currents. (Cool weather periods are associated with the higher energy events in the Great Lakes when current speeds are higher.) Integrating the hourly predictions was used to determine the plume delineation thereby providing the spatial extent of the regions where the PWQOs are achieved or exceeded.


6. MIKE-3 Model Calibration

Calibration involves testing the model to see how closely it simulates existing conditions. Once it is calibrated, the model can be used to determine the effluent plume behaviour and assess the water quality impacts due to the effluent discharge. The model was calibrated based on the existing data described above, including bathymetry, water quality, pH, currents and temperature.

Extensive testing was performed on the model to ensure the accuracy of the predictions. Many simulations have been made with different airports around the lake and, of these, Pearson has consistently provided the best agreement with observed data. NOAA has made available the hourly wind field covering Lake Ontario at a 5 km resolution. The wind field is more reliable than Pearson as it does not have any missing data or zero values. In addition, the wind field more accurately represents the effects of pressure cells over the lake surface. Wind based on one station is uni-directional over the lake, while the NOAA data is variable and more realistic. An Acoustic Doppler Current Profilers (ADCP) has been deployed by Ontario Power Generation at Pickering NGS for many years. The data collected has been used to calibrate the hydrodynamic currents predicted by the MIKE-3 model.

The accuracy of the model predictions are based on the Fourier Norm, or F-norm, which calculates the variance between observed and modeled current velocities. Assessing model calibration based on the variance between observed and modeled results is a standard statistical technique that is used in many scientific disciplines. In practical terms, the velocity is computed as a V component in the onshore-offshore (north-south) direction and the U component in the alongshore (east-west) direction. Equation (1) describes the Fourier Norm as:

0,

,

o

co

N

v

vvF

= where 21

2

1

1, ∑∆

=

−=tN

tcoco vv

Nvv [1]

and vo = observed data and vc

[(U

= computed data. A sample calculation would be:

o-Uc)2 + (Vo-Vc)2] / ( Uo2 + Vo2

A value of 0 means the model prediction is identical to the ADCP data. A value of 1 or more means the difference between the predicted vector component and observed vector component is larger than the amplitude of the vector. The F-norm score is a standard test of the model predictions and experience indicates that the good scores are usually in the range of 0.9, lower scores say 0.8 are very good and rare. The data are based on either 60 or 30 minute samples depending on how often the ADCP stores data. Our results for current velocity show F-norm values ranging from 0.6 to 0.9. Therefore, the model fit is considered to be in the range of very good to good. The basis for evaluating model calibration using F-norm is the modeller’s experience and expert opinion and is outlined in Table 6-1.

)


TABLE 6-1 Basis for evaluating model calibration using the variance between simulated and observed current velocities (F-norm) F-norm Qualitative assessment

0 Perfect model calibration

Less than 0.9 Very good

0.9 to 1 Good

Greater than 1 Poor

The model run was initiated in the spring time when the lake is thermally well-mixed at 4°C. This is a standard technique for model initiation because it allows a uniform temperature to be assigned throughout the lake. The model can then simulate the currents and heating/cooling through the summer and fall period. The temperatures and velocities predicted by the model are stored at hourly/half-hourly intervals, depending on the ADCP sampling frequencies. The F-norm is then calculated from the observations and model predictions.

The vertical resolution (Z-Coordinate system) was 2 m with 40 layers, sufficient depth for thermal stratification events to be well reproduced. Below a depth of 80 m, the lake bottom was assumed to exist as a single well mixed layer.

The wind stress was initially set constant at 0.0026, however predicted speeds were often greater than the observations, so the stress was reduced and set to vary depending on wind strength. The predicted speeds reduced to levels in better agreement with the observations.

Figures 6-1 and 6-2 show the predicted current speeds and directions for the OPG ADCP data from 2007 at the 1m depth layer. However, the ADCP only recorded data from October to December. From a modelling perspective, the trends are predicted correctly and results are acceptable.

5BMIKE-3 MODEL CALIBRATION


FIGURE 6-1 Comparison of Modelled Lake Current SPEED with OPG – ADCP Measurements



FIGURE 6-2 Comparison of Modelled Lake Current Direction with OPG-ADCP Measurements


The overall F-norm for the OPG ADCP was 0.67, a very good score meaning the model was able to accurately simulate the currents late in the year even after starting in May.

The NWRI ADCP data was partitioned into two periods as the meter was pulled for servicing from the water for several days at the start of July, the missing data were replaced with zero speed and direction to provide a complete data set. Figures 6-3 and 6-4 show the current speed and direction results at the 5 m depth layer.


FIGURE 6-3 NWRI Current Speed Comparisons – 5 m Depth - 2007


FIGURE 6-4 NWRI Current Direction Comparisons – 5 m Depth - 2007



The 5 m layer F-norm for this period was 0.84; a very good result. By comparison, the results using Pearson Airport wind data indicated a poor calibration with F-norm value of 1.32. Table 6-2 provides a breakdown of the F-norm scores for the three depths.

TABLE 6-2 NWRI F-norm DATA – 2007

Month 5m depth 10m depth 18m Depth

April - November 0.84 0.89 1.06

April-May 0.89 0.94 0.91

May 1 – June 1 0.98 0.97 0.93

June 1 – July 1 0.99 1.07 1.09

July-August 0.75 0.80 1.11

August- September 0.82 0.93 1.24

September-October 0.72 0.77 1.06

October November 0.57 0.62 0.99

The MOE Offshore ADCP had continuous records from April to October. The overall F-norm score was 0.854 at the 1 m depth, which is very good. Figures 6-5 and 6-6 show the current speed and direction time series. As with the NWRI data, the directional agreement is very good but the current speed variance is what reduces the correlation. Table 6-3 provides more details of the F-norm analysis.

TABLE 6-3 MOE Offshore F-norm Data – 2007

Month 1 m depth 6 m depth 12 m depth

Apr - Nov 0.85 0.88 1.01

May – Jun 0.83 0.91 1.15

Jun – Jul 0.98 0.95 1.22

Jul – Aug 0.95 0.92 1.04

Aug – Sep 0.81 0.95 0.94

Sep – Oct 0.82 0.86 0.93

Oct - Nov 0.66 0.63 0.67



FIGURE 6-5 MOE Offshore ADCP Comparisons – 2007



FIGURE 6-6 MOE Offshore ADCP Comparisons - 2007



The MOE nearshore ADCP also had a long term record and the overall score was 0.90 at the 1 m depth. The meter depth was only 6 m. The data from July onwards had many small data gaps which made analysis difficult as data replacement was required. The missing data was at depth as it appears the lake elevation may have fluctuated and the bottom bin was often missing. Figures 6-7 and 6-8 show the comparisons. Table 6-4 provides more details of the F-norm analysis. The nearshore zone has much higher frequency current reversals and is dominated by an easterly current direction.

TABLE 6-4 MOE Nearshore F-norm DATA - 2007

Month Surface 6 m depth 10 m depth

Apr - Nov 0.90 1.01 NA

May – Jun 0.94 1.04 NA

Jun – Jul 0.86 1.00 NA

Jul – Aug 0.95 1.00 NA

Aug – Sep 0.81 NA NA

Sep – Oct 0.93 NA NA

Oct - Nov 0.82 NA NA



FIGURE 6-7 MOE Nearshore ADCP Current Speed Comparisons - 2007



FIGURE 6-8 MOE Nearshore ADCP CurrentT Direction Comparisons - 2007



Overall the model has accurate prediction in the spring and fall period. The stratified period is more challenging and the accuracy drops off, but still has good directional response while the current speeds do not. The MOE nearshore location is shallow and may be affected by longshore wave action, a behaviour not accounted for in the MIKE-3 model. The offshore meters generally underestimate peak events, which may be due to insufficient vertical resolution or not large enough wind stress.

The temperature predictions for each ADCP are shown in Figures 6-9 to 6-12.



FIGURE 6-9 Comparison of Model Tempertaure Predictions vs OPG Temperature Data



FIGURE 6-10 Comparison of Model Temperature Predictions vs NWRI Temperature Data



FIGURE 6-11 Comparison of Model Temperature Predictions vs MOE Offshore Temperature Data



FIGURE 6-12 Comparison of Model Temperature Predictions vs MOE Nearshore Temperature Data


The ADCP only measures temperature at the meter depth. The model reproduces the spring and summer period quite well. There are upwelling/downwelling events that are simulated, although the temperature dips are not as large as observed. The correlation between the MOE offshore temperature and the predicted temperature at the ADCP depth is 0.918, which is a good score.


7. Model Correlation to TRCA Data

The following section presents MIKE-3 simulation results for the 2008 April to November period under actual plant effluent loads and including tributary loads that impact the Ajax-Pickering waterfront. These simulation results are compared with transect data from TRCA with the purpose of identifying similarities and differences between simulated and measured results.

7.1 Nearshore Water Quality Monitoring Data Ambient Lake Levels for TP An extensive water quality survey program was performed for the period 2007 to 2009 by the Regions and Toronto Region Conservation Authority. Seven transects were sampled several times each year for TP, soluble reactive phosphorus, total suspended solids, conductivity and E.coli for a total of 24 data points. Figure 7-1 shows the locations of each transect. The figure also presents the concentrations of TP measured on 10 Sep 2012 in terms of the size of the marker as described in the legend. Plots of the complete data set for the transects can be accessed at the site http://theskua.com/wqapp/wqapp.html. Overall these results reveal a trend in which the highest TP concentrations occur immediately at the shoreline and then decrease moving in the offshore direction.

The transect data is a valuable source of information on water quality in the near-shore environment around the Ajax-Pickering waterfront. In particular, the gradient of decreasing phosphorus concentrations in the offshore direction and the absence of “hotspots” surrounding the outfall diffuser point to the importance of other sources influencing near-shore phosphorus concentrations. Among these sources include local tributaries (including the Duffins Creek and Rouge River) and near-shore sediment deposits which are subject to “wave induced re-suspension”4

• Wave induced re-suspension of sediments, which has been suggested to be a key factor influencing near-shore TP concentrations, is not accounted for in the MIKE-3 model;

. The monitoring data also provides an opportunity for comparison with MIKE-3 simulation results. The following sections describe comparisons between MIKE-3 simulations with data from the transects. In attempts to correlate these results, however, certain limitations should be noted:

• The role of sedimentation in attenuating phosphorus plumes from tributary loads and the Duffin Creek WPCP outfall is not accounted for in the MIKE-3 model;

• Water quality monitoring samples from over 50 transect points were obtained over the course of a day and thus, unlike MIKE-3 simulation results, do not capture TP concentrations at a single point in time nor represent an average over a day.

4 Martin Auer (2011) “Monitoring, Modeling and Management of Nearshore Water Quality in the Ajax-Pickering Region of Lake Ontario”

http://theskua.com/wqapp/wqapp.html�

7-2 COPYRIGHT 2013 BY CH2M HILL CANADA LIMITED • ALL RIGHTS RESERVED • COMPANY CONFIDENTIAL

7.2 Model Inputs The MIKE-3 model as calibrated to the baseline condition was supplemented with time-series data to represent the Duffin Creek WPCP flows for 2008, flows from two other treatment plants including Highland Creek and Ashbridges Bay, and significant tributary loadings in the vicinity of the Ajax-Pickering waterfront. TP loadings from the plants have been calculated from daily measurements of average flow and effluent TP concentrations. Loadings from tributaries were provided by TRCA between Highland Creek and Harmony Creek and were calculated based on measured flows and monthly Event Mean Concentrations (Table 7-1). In cases where no measured data was available, tributary loadings were estimated based on the size of the watershed.

TABLE 7-1 Tributary Loadings Included in the MIKE-3 Model

TP Loading, kg/d

Loading Source Average 2008

Point Sources

Duffin Creek WPCP 238

Highland Creek WWTP 121

Ashbridges Bay TP 722

Tributaries

Rouge River 78

Highland Creek 22

Duffins Creek 52

Lynde Creek 24

Pringle Creek 5

Corbett Creek 2

Oshawa Creek 22

Harmony Creek/Black/Farewell 20


FIGURE 7-1 Transect Locations for Water Quality Survey - Station Identification Numbers Start at Shoreline and Increase Offshore

80

70

60

40

20

10

30

50


7.3 Comparison of Results Nearshore water quality monitoring data was translated to the MIKE-3 simulation grid in the region surrounding the Duffin Creek outfall diffuser using UTM coordinates. TP concentration isopleths were then developed based on linear interpolation of data with the assumption that TP concentrations measured at the shoreline could be extrapolated to all proximate shoreline gridpoints. For comparison to MIKE-3 simulation results from 2008, the average concentration for 2008 were selected. MIKE-3 results represent the average concentrations for the April to November simulation period whereas water quality monitoring data results represent isopleths developed based on the averages of ten sampling periods between 29-Apr and 17-Nov 2008. See results presented in Figures 7-2 and 7-3.

TP concentration isopleths developed using the water quality monitoring data show that TP concentrations tend to be highest along the shoreline and at the location of Duffins Creek. The source of the elevated shoreline TP concentrations, with the absence of a logical pathway from the diffuser, indicates that these concentrations are not directly from the diffuser. The most probable explanation for these concentrations is that they are derived from a combination of shore based loads (Duffins Creek and stormwater) and wave induced re-suspension of historic depositions of particulate phosphorous in storm runoff from tributaries like Duffins Creek. As discussed, the MIKE-3 model has not accounted for either sedimentation or re-suspension of sediments and so this behaviour is not captured in the model. Interestingly, the TP “hot-spot” simulated around the Duffin Creek diffuser using the MIKE-3 model is not detected by the water quality monitoring transect data. This suggests that MIKE-3 simulation results tend to over-predict the impacts of the outfall diffuser on local water quality. Possible reasons for this may relate to model calibration to ambient current speeds, simulation of the rapid mixing in the near-field zone, or the fact that the model simulates TP as a conservative substance that is not subject to removal by sedimentation or biological uptake.


Figure 7-2 Concentration isopleths for TP - averages of TRCA transect data for 2008

Figure 7-3 Concentration isopleths for TP – average of 2008 simulation results from MIKE3

> 0.025 mg/L (Red)

< 0.025 mg/L (yellow)

< 0.02 mg/L (Green)

< 0.015 mg/L (light blue)

< 0.01 mg/L (Dark blue)

> 0.025 mg/L (Red)




< 0.02 mg/L (Green)

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake


8. Baseline Modelling – 520 ML/d

One of the conditions of the approval of the Schedule C Class Environmental Assessment for the “Provision of Additional Capacity at the Duffin Creek Water Pollution Control Plant” (September 2006) was that the outfall limitations be addressed before flows reached 520 ML/d. This is the minimum flow at which the MOE assumed that dilution requirements of 20:1 would not be met. Consequently, a constant flow of 520 ML/d is the flow considered as the baseline for modelling, which future flows and outfall configurations will be modeled against. Water quality variables simulated in the model were total phosphorus and un-ionized ammonia.

8.1 Existing Outfall The existing outfall is approximately 1 km offshore with a 183m long diffuser. The diffuser was represented in the model as two sources adjacent to each other but aligned offshore. The total flow rate of 520 ML/d was apportioned into 260 ML/d for each grid cell with the exit velocity set to 2.4 m/s as calculated based in the number of ports and their dimensioning. The exit direction was offshore and the vertical angle was set to 10° above vertical. This representation allows the momentum produced by the diffuser to be captured in the model over two grid cells and one single depth layer, the bottom layer, in which flow is assumed to be released. There are no methods in the MIKE-3 software to allow variable depth i.e. spatial releases based on ambient buoyant conditions such as those predicted by near-field models like CORMIX.

8.2 Effluent Certificate of Approval Requirements The Certificate of Approval was revised in 2007 to reflect the expansion requirements identified in the Schedule C Class EA for “Provision of Additional Capacity at the Duffin Creek Water Pollution Control Plant” and the Minister’s conditions of approval. The CofA compliance limits that were taken into consideration for use in the baseline model scenario are:

• Total Phosphorus: 0.6 mg/L (equates to the 311kg/d mass loading limit at 520MLD) • Total Ammonia Nitrogen: 6 mg/L and 10mg/L during summer/fall (May 1 to Oct 31)

and winter months (Nov 1 to Apr 30) respectively

The above concentrations were used in modelling effluent levels.

Since the Stage 3 expansion has come on-line in the fall of 2010, the plant has been performing well below the effluent compliance limits. The 2011monthly average concentrations for total phosphorous, total ammonia nitrogen, and unionized ammonia is 0.4mg/L, 1.5 mg/L, and 0.001 mg/L respectively. The end-of-pipe unionized ammonia level is below the acute toxicity level for fish.


8.3 Provincial Water Quality Objectives As described in Section 3, Phosphorous is considered a nuisance nutrient that may affect the surrounding aquatic environment. In particular, Total Phosphorus (TP) has been shown to contribute to increased algal formation at concentrations greater that the interim Provincial Water Quality Objective (PWQO) of 0.02 mg/L in lakes.

Un-ionized ammonia (UIA) is an important measure of the level of effluent toxicity to aquatic organisms. The PWQO for UIA is 0.02 mg/L. Un-ionized ammonia is calculated from the measured value of total ammonia based on both temperature and pH data from the measured location.

8.4 Receiving Water Characterization Loading from Duffins Creek Duffins Creek is a contributor to pollutant loading to the Lake. Consequently, the model was run with and without the influence of Duffins Creek for comparison purposes.

The Toronto & Region Conservation Authority (TRCA) provided time series of flow from Duffins Creek for 2007 on an hourly basis. Monthly Event Mean Concentrations (EMC) for TP was provided as well. The EMC were used as input of concentration of TP in the Creek flow. It was assumed that the ammonia levels were zero as there should be no sources along the Creek.

Ambient Lake Levels for TP The TRCA transect data discussed in section 7 provides a valuable source of data for evaluating the ambient TP concentrations in the region surrounding the Ajax-Pickering waterfront. Figure 8-2 shows the locations of each transect, the shoreline station would be labeled 10 and then each offshore station would be 110, 140, 1,100 m offshore and 1,500 m offshore. The MOE uses the 75th percentile to define the ambient water quality. Figure 8-1 summarizes the 75th percentile for each station showing the highest TP concentrations occur immediately at the shoreline and then decrease as one moves offshore. At the location of the existing Duffin Creek WPCP outfall, the results indicated that the water quality is better than the PWQO. The ambient TP level would most likely be found at the furthest offshore stations, away from shoreline discharges and the diffuser. The average of the 75th percentile of the offshore stations is 0.01 mg/L. Regarding the TP concentrations measured at the shoreline, it is concluded that shoreline discharges and non-point loadings are responsible for these higher concentrations. This is confirmed by the fact that concentrations at sampling points surrounding the outfall diffuser are lower than concentrations measured at the shoreline. Although these shoreline loadings are not explicitly included in the MIKE-3 model, their influence is accounted for insomuch as they contribute to the offshore ambient TP concentration of 0.01 mg/L. Plots of the complete data set for the TRCA transects can be accessed at site http://theskua.com/wqapp/wqapp.html.

Dr. Howell, of the MOE, presented results of his survey of the TP levels in Lake Ontario at the 2010 Lake Erie Millenium Network – April 2010, “Patterns in Nutrients over Dressena-Cladophora Impacted Shoreline” Slide 7 is presented, which show the TP levels offshore of Port Hope in Figure 8-2. The offshore levels of TP range from 0.004 mg/L to 0.007 mg/L.

http://theskua.com/wqapp/wqapp.html�


Based on the results of surveys conducted by TRCA and Dr. Howell of the MOE, it is proposed that the ambient levels of the Lake Ontario grid (2,430 m and 810 m) resolution be set at 0.007 mg/L and the nested grids in the nearshore area of Duffins Creek ambient level set at 0.01 mg/L.

7BBASELINE MODELLING – 520 ML/D


FIGURE 8-1 75th Percentile TP by Station

00.005

0.010.015

0.020.025

0.030.035

0.040.045

10 110014001100011500120001300020 210024002100021500220002300030 310034003100031500320003300040 410044004100041500420004300050 510054005100051500520005300060 6100640061000615006200063000710074007100071500720007300080 8100840081000815008200083000

TP

ug.

L

Station Name

75th Percentile Phosphorusby Station



FIGURE 8-2 Howell Presentation - TP Offshore Lake Ontario



8.5 Total Phosphorus in Lake Ontario under the 520 ML/d Baseline Scenario TP was modelled as a conservative parameter meaning no assimilation was assumed in the model. In reality, there would be some assimilation in the actual plume as biological processes convert the TP into biomass and this would lead to lower measured concentrations. The results presented herein are therefore conservative, and impacts under existing conditions are expected to be less.

The model was run to simulate lake conditions from April 1 to November 27 for a total of 5,750 hours. The hourly average TP levels were enumerated for the surface layer and the total number of hours the TP level was above the PWQO of 0.02 mg/L were determined with just the effluent discharge and with the added input from Duffins Creek, showing no significant difference. Figure 8-3 shows the mixing of TP as defined by the 90th percentile.

FIGURE 8-3 TP mixing zone as defined by the 90th

percentile

Outfall

Ajax Water Intake



A summary of the spatial and temporal extent of the TP surface plume is presented in Table 8-1 for results simulated with and without inputs from Duffins Creek. The results indicate that Duffins Creek has minor impact on TP levels in the effluent plume, but does influence TP concentrations in the near shore. As presented in Figures 8-4, the mixing zone for the 90th

Using the 90th percentile criteria, the mixing zone is found to not impinge on the shoreline or the Ajax WSP intake. It should be noted that the peak levels will not occur simultaneously; rather each grid point will experience a peak at different times during the simulation period.

percentile isopleths has an outside envelope of the most extreme movement in an area 2.5 km to the west, 2.5 km to the east, 0.2 km to the north, and 0.6 km to the south of the diffuser.

TABLE 8-1 Spatial and Temporal Extent of Surface TP Plume

Hours above PWQO (0.02mg/L)

Number of grids without Duffins

Creek (90m x 90m)

Number of grids (90m x 90m) with

Duffins Creek

Area (ha) without Duffins

Creek

Area (ha) with flows from

Duffins Creek

4,000 to 5,000 1 1 0.81 0.81

3,000 to 4,000 6 6 4.8 4.8

2,000 to 3,000 30 32 24.3 25.9

1,000 to 2,000 129 132 104 107

100 to 1,000 1281 1319 1037 1068

The results presented in Figure 8-5 present average concentrations for each of the grid points for the April to November simulation period. The highest peak instantaneous level is 0.119 mg/L and is located at the discharge points, as expected. These results indicate that, on average, the mixing zone in which PWQO for TP is exceeded does not impinge on the shoreline or surrounding features such as the Ajax WSP intake.

The areas of the lake impacted by elevated TP levels due to the discharge are mainly toward the west and extend offshore as well as onshore. These simulations do not account for any assimilation of TP to the environment. If the surface plume is transported beyond the 90 m grid boundaries, it is likely that the plume will return at a highly diminished level since some the TP would be assimilated in the environment. The areas shown are more likely the result of slow currents and short term current reversals rather than long term buildup of TP. Observations in the past several years show this to be the case as seen in the TRCA and MOE sampling survey, the plume is not readily apparent.



FIGURE 8-4 Average Surface TP Levels

8.6 Un-Ionized Ammonia Levels in Lake under 520 ML/d Baseline Scenario Ambient Ammonia levels were surveyed in 2008 by the MOE. Figure 6-6 show the ammonia levels on survey date July 29, 2008. The entire data set can be found at http://theskua.com/ajax. The 75th percentile of all data from the five surveys is 0.008 mg/L. The ambient levels in the lake were set to this value.

> 0.025 mg/L (Red)


< 0.02 mg/L (Green)



Outfall

Ajax Water Intake

http://theskua.com/ajax�



FIGURE 8-5 MOE Ammonia Survey

The Un-Ionized Ammonia (UIA) was calculated using the predicted surface layer concentration of ammonia and the corresponding temperature in the grid, along with the pH measured at the Ajax WSP intake. Ammonia was also modelled as a conservative parameter. The Ajax data, summarized in Table 8-2, were measured daily whereas the model data were simulated hourly. It was assumed that the pH was constant over the grid for the day of record. The synoptic data were used to determine the UIA, and then the hours above the PWQO of 0.02 mg/L were enumerated. The simulation results were partitioned into a winter and summer period, as required by MOE, since the ammonia levels in the effluent vary in these periods.



TABLE 8-2 Summary of Temperature and pH Data for the Ajax WSP intake Month Average 75th percentile

Temp pH Temp pH

January 4.33 8.15 5.00 8.18

February 2.66 8.17 3.00 8.21

March 2.98 8.17 3.10 8.21

April 4.37 8.18 5.00 8.25

May 7.15 8.20 7.95 8.27

June 7.43 8.10 8.15 8.18

July 10.19 8.17 14.10 8.27

August 15.30 8.15 17.50 8.34

September 14.69 8.09 17.75 8.23

October 12.46 8.09 16.75 8.25

November 7.39 8.08 8.15 8.14

Figures 8-6 and 8-7 (90th percentile) and Figures 8-8 and 8-9 (average concentrations) present the simulation results for UIA. The area impacted is not dominated by a particular direction, as was found with the TP results. The instantaneous winter peak level is 0.067 mg/L and the summer peak level is 0.142 mg/L. Averaging the simulated UIA levels, presented in Figures 8-8 and 8-9, gives maximum average levels of 0.019 mg/L (winter) and 0.032 mg/L (summer). The UIA levels are lower in the winter, even with the effluent ammonia level higher than summer, primarily because of the effect of colder water temperatures on the UIA factor. Figures with Duffins Creek are not included as the contribution of ammonia in the Creek discharge was assumed to be negligible and the Creek’s influence would therefore be limited to providing dilution water at its discharge point.



FIGURE 8-6 Mixing zone for UIA is non-existent as defined by the 90th

percentile – Winter Period

FIGURE 8-7 Mixing zone for UIA as defined by the 90th

percentile - Summer Period

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake



FIGURE 8-8 Average Surface UIA Levels – Winter Period

FIGURE 8-9 Average Surface UIA Levels - Summer Period

Table 8-3 presents a summary of the spatial and temporal extent of the UIA surface plume. The effect of Duffins Creek is to impact dilution and shoreline distribution of the ammonia effluent plume.

< 0.010 mg/L (light blue) < 0.005 mg/L

(Dark blue)

< 0.001 mg/L (purple)

< 0.020 mg/L (yellow) < 0.015 mg/L

(Green)

< 0.010 mg/L (Light blue)


Outfall

Ajax Water Intake

Outfall

Ajax Water Intake



TABLE 8-3 Spatial and Temporal Extent of Surface UIA Plume

Winter Period November 1 to April 30

Hours above PWQO (0.02mg/L)

Number of grids (90m x 90m) without

Duffins Creek

Number of grids (90m x 90m) with

Duffins Creek

Area (ha) without Duffins Creek

Area (ha) with Duffins Creek

400 to 500 0 0 0 0

300 to 400 0 0 0 0

200 to 300 1 1 .81 .81

100 to 200 2 2 1.62 1.62

1 to 100 31 30 25.1 24.3

Summer Period May 1 to October 31

400 to 500 2 2 1.62 1.62

300 to 400 6 6 4.86 4.86

200 to 300 15 15 12.15 12.15

100 to 200 60 60 48.6 48.6

1 to 100 2,531 2,523 2,050 2,043

Using the 90th

• Winter—no area

percentile isopleths, the extent of the plume in which PWQO for UIA are exceeded is:

• Summer—90 m west, 90 m south, and 270 m east of the diffuser.

As in the TP results, the size of this plume zone is influenced by the zone of initial mixing as generated by the outfall diffuser. Beyond this zone, changing current speeds and direction influence the migration of the plume. The variable nature of current speeds and directions can be observed from the Compass Rose of current speeds at the nearby NRWI ADCP, presented in Figure 8-11.

Relevant to water quality, the predicted total ammonia nitrogen time series at the depth layer (7) representative of the Ajax Intake is shown in Figure 8-10. The peak ammonia level of 0.134mg/L occurs in mid May and is well below the drinking water guideline of 0.5 mg/L.


FIGURE 8-10 Ajax Intake Ammonia Time Series


The Pickering NGS discharge will pull in some of the lake water with diluted effluent and then discharge it back to the lake with a small temperature increase. The increase in temperature has the potential to raise the level of UIA in that water – however the discharge is not included in this model.

FIGURE 8-11 Compass Rose representation of Current Speeds (in m/s) and Directions – NWRI ADCP

8.7 Impact of Pickering NGS To assess the impact of the Pickering NGS and its potential decommissioning in the future, the baseline model was rerun with inflows and outflows to the nuclear generation facility. Inflows were simulated from a single grid point at the Pickering NGS headland and outflows were simulated from opposite points of the same headland using a time-series based on recorded flows and assuming a temperature differential of 10 ˚

C relative to the lake temperature at the discharge point.

Simulation results presented in Figures 8-12 and 8-13 compare flow vectors with and without the Pickering NGS. These results show a significant induced current in the offshore direction with the NGS outflows (Figure 8-12) that is not present in the model results


without NGS outflows (Figure 8-13). Simulation results indicate that the impact of this induced current is to cut off and reduce current speeds in the along-shore direction. This is consistent with the results of Leon et al. that show that the NGS outflows create “thermal bars” that “drive some of the small scale circulation”5

.

Average TP concentrations are presented in Figure 8-14 and 8-15, respectively, based on simulations with and without the Pickering NGS outflows. These results are very similar with notable differences only occurring in areas with concentrations below 0.015 mg/L. In contrast, the simulated zone in which TP exceeds 0.02 mg/L is almost identical in size and shape. These simulation results indicate that, while the NGS outflows do impact the local circulation patterns and currents at the shoreline, overall impacts on the performance of the outfall diffuser are insignificant. Consequently, decommissioning of the Pickering NGS would not be expected to have a significant impact on the performance of the outfall diffuser.

5 Leon et al. (2012) “Nested 3D modeling of the spatial dynamics of nutrients and phytoplankton in a Lake Ontario nearshore zone” Journal of Great Lakes Research.


Figure 8-12 Circulation patterns as predicted by the model with the Pickering NGS inputs

Figure 8-13 Circulation patterns as predicted by the model without the Pickering NGS inputs



Figure 8-14 Average concentration isopleths at 520 MLD with the Pickering NGS

Figure 8-15 Average concentration isopleths at 520 MLD without the Pickering NGS


9. Summary and Conclusions

9.1 Summary of Results 9.1.1 CORMIX MODEL: Near-Field Analysis The CORMIX near field analysis indicates that the initial mixing ratio of the existing diffuser is 22.8:1 at the baseline flow of 520 MLD. Based on this 22.8:1 initial mixing ratio calculated using the CORMIX software, the mixing zone extends into the far-field zone. As such, a far-field analysis was required to further delineate the mixing zone. The MIKE-3 model was used for this purpose.

9.1.2 MIKE 3 MODEL: Far-Field Analysis The calibration with ADCP currents was successful; some locations had better model agreement than others. Generally the model has better predictions in the weakly to non-stratified periods. The temperature response of the model was very good for the entire period of simulation. The existing discharge, modelled over two grid points, simulated the momentum of the plume and the advection-dispersion process in the far-field.

The model predicted the spatial and temporal extent of the effluent plume for both TP and ammonia. UIA was subsequently determined from synoptic temperature and pH data. Integration of the hourly results and using the PWQO limits, the model results were used to define the extent of the zone in which UIA and TP PWQO were exceeded.

The results indicate that, on average, the mixing zone does not impinge on the shoreline or Ajax WSP intake. Based on the mixing zone as defined by the 90th

The results indicate that the UIA effluent plume is much smaller than that for TP. Out of 5,750 hours of simulation (April to November) the areas ranged from: 2,110 Ha between 1 and 100 hours over the PWQO and less than 30 Ha had between 400 and 500 hours. Using the same 10% above the PWQO isopleths as in the TP method, the mixing zone for UIA is:

percentile isopleth, the mixing zone extends approximately 2.5 km to the west, 2.5 km to the east, 0.2 km to the north, 0.6 km to the south of the outfall diffuser. The highest instantaneous (1 hour) level is 0.119 mg/L and is located, as expected, at the discharge points.

− Winter—no area − Summer—90 m west, 90 m south, and 270 m east of the diffuser.

While, the peak UIA was found to be above the PWQO, the spatial and temporal extents of these exceedances are very limited; again much less than that for TP. The UIA levels at the Ajax Intake were reviewed from a drinking water quality perspective and were noted to be well below the guidelines.

The model results that included the flow from Duffins Creek showed there is some shoreline impact from the Creek with TP, while the UIA results showed the Creek flow provides some relief due to dilution, as the Creek is assumed to be free of ammonia.

REFERENCES


10. References

Abdel-Gawad, S.T. (1985) “Mixing and Decay of Pollutants from Shore-based Outfalls Discharging into Cross-flowing Streams”. Ph.D. Thesis, Department of Civil Engineering, University of Windsor, Windsor, ON, Canada.

Auer, M.T. (2011) “Monitoring, Modeling and Management of Nearshore Water Quality in the Ajax-Pickering Region of Lake Ontario”. Peer review report accessed on 18 Jan 2013 from http://www.trca.on.ca/dotAsset/119784.pdf

Bowen and Booty (2012) “Tributary Loads To Nearshore Lake Ontario”. Presentation from the Lake Ontario Collaborative Workshop. Black Creek Pioneer Village, 20 Nov 2012. Accessed on 21 January 2013 from http://www.ctcswp.ca/files/LOC_20121122_Bowen.pdf

Environment Canada “Phosphorus Levels in the Great Lakes”. Environment Canada web page accessed on 18 Jan 2013 from http://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=A5EDAE56-1

Holleck, K. “Ecological Indicators and Sustainability of the Lake Ontario Ecosystem”. Cornell Biological Field Station report accessed on 18 Jan 2013 from http://www.seagrant.sunysb.edu/glsportfish/pdfs/LOnt-EcoIndicators-Fall08.pdf

Howell, T. (2012) “Water Quality of Nearshore Lake Ontario” Ontario Ministry of Environment presentation accessed on 18 Jan 2013 from http://www.ctcswp.ca/files/THowell-LO_WaterQuality.pdf

Leon, L.F., Smith, R., Mailkin, S., Depew, D., Hecky, R.E. (2009) “Modelling and analysis of Cladophora dynamics and their relationship to local nutrient sources in a nearshore segment of Lake Ontario”. University of Waterloo report accessed on 18 Jan 2013 from http://www.ajax.ca/en/doingbusinessinajax/resources/PDENG_D_UWReportOct2009-final.pdf

Leu, S-Y, Chan, L, Stenstrom, M.K. (2010) “Toward Long SRT of Activated Sludge Processes: Benefits in Energy Saving, Effluent Quality, and Stability” Proceedings of the Water Environment Federation, WEFTEC 2010. New Orleans, U.S.A.

Makarewicz, J.C., Booty, W.G., Bowen, G.S. (2012) “ Tributary Phosphorus Loads to Lake Ontario”. Journal of Great Lakes Research, 2012, 38:14-20.

Martin, G. (2010) “Nutrient sources for excessive growth of benthic algae in Lake Ontario as inferred by the distribution of SRP” University of Waterloo Master’s Thesis, Waterloo, Canada.

McCorquodale, J.A. (2007) “Storm-water jets and plumes in rivers and estuaries”. Canadian Journal for Civil Engineering, CSCE, 34(6):691-702.

http://www.trca.on.ca/dotAsset/119784.pdf�

http://www.ctcswp.ca/files/LOC_20121122_Bowen.pdf�

http://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=A5EDAE56-1�

http://www.ec.gc.ca/indicateurs-indicators/default.asp?lang=en&n=A5EDAE56-1�

http://www.ctcswp.ca/files/THowell-LO_WaterQuality.pdf�

http://www.ajax.ca/en/doingbusinessinajax/resources/PDENG_D_UWReportOct2009-final.pdf�

http://www.ajax.ca/en/doingbusinessinajax/resources/PDENG_D_UWReportOct2009-final.pdf�


Painter and Kamaitis (1987) “Reduction of Cladophora Biomass and Tissue Phosphorus in Lake Ontario, 1972–83” Canadian Journal of Fisheries and Aquatic Sciences, 1987, 44(12): 2212-2215.

Stevens and Neilson (1987) “Response of Lake Ontario to Reductions in Phosphorus Load, 1967–82” Canadian Journal of Fisheries and Aquatic Sciences, 1987, 44(12): 2059-2068.

Thorburn, M. (2011) “Setting Water Quality Targets for the Nearshore”. Ontario Ministry of Environment presentation accessed on 18 Jan 2013 from http://www.latornell.ca/files/2011_sessions/Latornell_2011_F1A_Mary_Thornburn.pdf

Tomlinson, L., Auer, M.T., Bootsma, H.A., Owens, E.M. (2010) “The Great Lakes Cladophora Model: Development, testing, and application to Lake Michigan” Journal of Great Lakes Research, 36(2):287-297.

http://www.latornell.ca/files/2011_sessions/Latornell_2011_F1A_Mary_Thornburn.pdf�

Alternatives Modelling

1

COPYRIGHT 2013 BY CH2M HILL, INC. • COMPANY CONFIDENTIAL

T E C H N I C A L M E M O R A N D U M Duffin Creek WPCP – Outfall EA – Modelling Results for Alternatives

PREPARED FOR: Regional Municipality of Durham, Regional Municipality of York PREPARED BY: CH2M HILL DATE: January 9, 2013 PROJECT NUMBER: 378698

The purpose of this memo is to evaluate alternatives for expanding outfall capacity based on performance standards with respect to:

• Initial dilution capacity: the dilution achieved in the near-field region where mixing processes are driven by momentum induced by buoyancy and effluent exit velocities from the diffuser ports.

• Size of the mixing zone and its non-interference with beneficial uses such as water supply intakes, other effluent discharges, bathing beaches, fish spawning areas, or fish migration routes (in accordance with Policy 5 of the MOE’s Water Management1

• Meeting or achieving better than the relevant Provincial Water Management Policy statements and Procedure B-1-5 guidelines for mixing zones.

).

1 Summary and Conclusions The modelling results in this memo relate to the following five alternatives within the EA process including:

Alternative 1 - Optimized operation of the Upgraded/Expanded Plant: This alternative achieves an initial dilution of 19:1 at a capacity of 630 MLD and would therefore require relaxation of the MOE’s 20:1 guideline (Procedure B-1-5, Section 4.4.2). MIKE-3 modelling results indicate that the resulting far field mixing zone for TP does not impinge on shoreline features, the UIA mixing zone is very small and does not extend far beyond the near-field region, and Total Ammonia Nitrogen (TAN) concentrations remain well below the drinking water standard at the Ajax WSP intake. In accordance with the criteria set out in Procedure B-1-5, this alternative would achieve the intent of the Provincial Water Management Policies.

Alternative 2 - Modified Diffuser: This alternative achieves an initial dilution of 22:1 at a capacity of 630 MLD. MIKE-3 modelling results indicate that the resulting far field mixing zone does not impinge on shoreline features, the UIA mixing zone is very small and does not extend far beyond the near-field region, and TAN concentrations remain well below the drinking water standard at the Ajax WSP intake. In accordance with the criteria set out in Procedure B-1-5, this alternative would achieve the intent of the Provincial Water Management Policies.

Alternative 3 - Tertiary Treatment: This alternative is identical to Alternative 1 in that it provides a capacity of 630 MLD and achieves an initial dilution of 19:1. The lower effluent TP concentration of 0.15 mg/L, however, results in a smaller mixing zone for TP. As in Alternative 1, this alternative would require relaxation of the MOE’s 20:1


2


guideline. Simulation results for UIA and TAN are identical to those in Alternative 1. In accordance with the criteria set out in Procedure B-1-5, this alternative would achieve the intent of the Provincial Water Management Policies.

Alternative 4 - Extension of the Existing outfall: This alternative achieves an initial dilution greater than 30:1 at a capacity of 630 MLD. MIKE-3 modelling results indicate that the resulting far field mixing zone does not impinge on shoreline features, the UIA mixing zone is confined to the near-field region, and TAN concentrations remain well below the drinking water standard at the Ajax WSP intake. In accordance with the criteria set out in Procedure B-1-5, this alternative would achieve the intent of the Provincial Water Management Policies.

Alternative 5 - Construction of a New Outfall: This alternative achieves an initial dilution of 76:1 at a capacity of 630 MLD (53:1 at the ultimate capacity of 890 MLD) meaning that the mixing zone would be confined to a very small area in the near-field region. MIKE-3 simulation results confirm this result. Total ammonia nitrogen concentrations remain well below the drinking water standard at the Ajax WSP intake. In accordance with the criteria set out in Procedure B-1-5, this alternative would achieve the intent of the Provincial Water Management Policies.

2 Approach 2.1 Water Quality Assessment The MOE has set Provincial Water Quality Objectives (PWQO) for constituents of concern with the goal of ensuring that surface waters are of a quality that is satisfactory for aquatic life and recreation. Water bodies are regulated according to one of two policies:

• Policy 1: “In areas which have water quality better than the Provincial Water Quality Objectives, water quality shall be maintained at or above the Objectives.”

• 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.”

Lake Ontario is Policy 1 and thus discharge of effluent is permissible so long as water quality is maintained at or above the objectives. The MOE recognizes that the cost of treating all waste discharges to the PWQO’s may not be justified nor technically feasible, as is the case for TP, and so provides for the use of a mixing zone. A mixing zone is defined as an area of water contiguous to a point source where the water quality does not comply with one or more of the Provincial Water Quality Objectives. Policy 5 of Water Management2

“Mixing zones should be as small as possible and not interfere with beneficial uses. Mixing zones are not to be used as an alternative to reasonable and

practical treatment.”

states that:

The water quality constituents presented in Table 1, are the most sensitive of the PWQO and serve as chemical and physical surrogates of healthy populations of aquatic biota representing a satisfactory level of quality for surface waters. The Duffin Creek WPCP discharges final effluent concentrations of E. coli below the PWQO and as a consequence E. coli is not a parameter of concern. The assessment therefore focuses on meeting PWQO for TP and UIA.


DUFFIN CREEK WPCP – OUTFALL EA – MODELLING RESULTS FOR ALTERNATIVES

3


Table 1 - Water Quality Objectives for key parameters Parameter Concentration Limit Un-ionized ammonia (UIA)1 20 ug/L Total ammonia nitrogen (TAN)2 500 ug/L Total phosphorus (TP)1 20 ug/L E. coli1 100 E. coli per 100 mL 1Provincial Water Quality Objective (PWQO) 2

Great Lakes Water Quality Agreement

For each alternative, the approach to assessing impacts on water quality is to (1) identify its ability to achieve performance standards with respect to initial dilution capacity in the near field region as set out in Section 4.4.2 of Procedure B-1-5, and (2) in accordance with Policy 5 ensure that the mixing zone does not interfere with beneficial uses such as water supply intakes, other effluent discharges, bathing beaches, fish spawning areas, or fish migration routes. With regard to these beneficial uses, TP and UIA are considered the most sensitive parameters with potential impacts to algal blooms and fish toxicity, respectively. TAN concentrations are assessed independently of UIA at the location of Ajax WSP intake because of its potential impacts on, and as a surrogate for, overall raw drinking water quality.

The dilution ratios required to achieve the PWQO identified in Table 1 can be calculated based on the concentrations in the effluent and the ambient water using the equation below. Based on an ambient TP concentration of 0.01 mg/L and an effluent compliance limit of 0.5 mg/L, a dilution ratio of 49:1 is required to achieve the PWQO. Based on effluent compliance limits for TAN of 6 and 10 mg/L for summer and winter, respectively, the required dilution ratio for UIA is less than 20:1 to achieve the PWQO. It should be noted that the dilution requirement for UIA is significantly lower than for TP because the UIA concentrations in the ambient lake water are low. The following sections describe the numerical models used to calculate dilutions in the near-field and far-field regions under a constant flow of 630 MLD.

𝑋 =𝐶𝐸𝑓𝑓 − 𝐶𝐴𝑚𝑏

𝐶𝑃𝑊𝑄𝑂 − 𝐶𝐴𝑚𝑏

Where,

Ceff

C = effluent concentration (mg/L)

amb

C = lake ambient concentration (mg/L)

PWQO

= PWQO concentration (mg/L)

2.2 Near-Field Dilution The CORMIX model is a standard tool used by the MOE for calculating initial dilution in the near-field region because it is particularly adapted to modeling behavior where momentum and buoyancy of the effluent jet dominate the mixing process. The approach to calculating the near-field dilution of each alternative is to first calculate the minimum port diameter required to pass the peak wet weather flow at an average annual daily flow (AADF) of 630 MLD, using the flow peaking factor of 2.5. The rationale for this approach is that smaller port diameters favor greater exit velocities and higher near-field dilutions but a minimum port diameter is required to limit head losses through the diffuser and avoid flooding within the Duffin Creek WPCP. This port diameter, together with other parameters such as current speed and ambient depth, were then used as inputs to the CORMIX model to calculate the initial dilution ratio in the near field region. The inputs to the CORMIX model for

4


each alternative were, as appropriate, consistent with those used in the Baseline Report and are presented in Appendix C. Hydraulic head losses through the outfall and diffuser were calculated based on the Hazen-Williams equation for the outfall pipe and ‘Minor-Loss’ relationships for areas of flow disturbances such as bends, contractions, expansions and the exit from the diffuser ports. Hazen-Williams friction factors range from 60 for old pipes in poor condition to 140 for extremely smooth pipes3

Details of the hydraulic calculations are presented in Appendix B.

. A standard friction factor used for designing new outfalls is 100 which assumes the condition of the pipe will not deteriorate to ‘poor’ over the course of its lifespan. A value of 90 was used for the purposes of this assessment.

Hazen-Williams equation for pipe friction:

ℎ𝑓 =10.67 × 𝐿 × 𝑄1.85

𝐶1.85 × 𝑑4.87

Where,

hf

L = length of pipe, m = pressure loss over a length of pipe, m

Q = volumetric flow rate, m3

d = inside pipe diameter, m /s

C = roughness coefficient

Minor-Loss equation:

ℎ = 𝐾 ×𝑣2

2𝑔

Where,

h = pressure loss from minor losses, m K = minor loss coefficient (no units) g = acceleration due to gravity, m/s2

v = velocity, m/s

2.3 Far-Field Dilution MIKE-3 is a 3-dimensional, hydrodynamic model that is used to simulate the behavior of the effluent plume in the far-field region where momentum and buoyancy of the effluent jet have dissipated; it is one of the few models that is accepted by the MOE for this purpose. The model was calibrated to ambient current and temperature data from off-shore Acoustic Doppler Current Profilers, as described in the Baseline Modeling report. This calibrated model has been used to simulate the five alternatives described in this memo based on the critical period of 1-Apr to 27-Nov. The months of December to March are considered non-critical due to higher mixing energy and lower temperatures in the Lake during this period. The effluent compliance limits for total phosphorous and ammonia were used to run the simulation. The compliance limits for ammonia for the winter period (Nov 1 to Apr 30) and summer/fall period (May 1 to Oct 31) are 10 and 6 mg N/L respectively. The respective seasonal compliance limit was used in the simulation. The far field mixing zones for TP and UIA have been defined using the MIKE-3 model based on the area outside of which concentrations are below PWQO 90% of the time i.e. the 90th

3 Handbook of Hydraulics for the Solution of Hydraulic Engineering Problems, Seventh Edition, Brater, E.F., et al, 1996.

percentile. The


5


90th

percentile criterion was chosen to delineate the mixing zone because it is conservative but screens out the most extreme events which are too transient to significantly impact on the environment and cause a serious algal problem outside the mixing zone. Potential impacts to drinking water intakes were identified using the MIKE-3 model by simulating TAN at the Ajax WSP intake.

3 Near-Field Mixing Zones – CORMIX Modelling The findings from the near-field assessment for each alternative are provided in this section. Table 2 provides a summary of the initial dilution at the edge of the near-field mixing zone for the baseline and Alternatives 1 to 5. Hydraulic calculations are provided in Appendix B. The CORMIX model inputs and outputs for each alternative are provided in Appendix C and D respectively. Figure 1 presents the coordinate system used by CORMIX with near field mixing zone for the baseline condition.

Table 2 – Initial Dilution at Edge of Near-Field Mixing Zone Parameter Baseline Alt. 1 Alt. 2 Alt. 3 Alt. 4 Alt. 5

Initial Dilution at edge of Near-Field Mixing Zone 23:1 19:1 22:1 19:1 33:1 76:1

Figure 1 Plan View 520 ML/d – Coordinate System Used By CORMIX

3.1 Alternative 1 – Upgraded/Expanded Plant This alternative achieves an initial dilution of 19:1 at a capacity of 630 MLD by opening up all 63 diffuser ports in the existing diffuser using fixed, 275 mm diameter ports. Given that this alternative does not meet the 20:1

6


guideline as specified in Procedure B-1-5 (MOEE, 1994), relaxation of this requirement would be necessary for this alternative to achieve acceptance by the MOE. The advantage to this alternative, however, is that it retains the existing outfall infrastructure which was constructed in the 1970s and, based on an estimated 75 year life-span, still has 35 years of useful life. 3.2 Alternative 2 – TideFlex This alternative achieves an initial dilution of 22:1 at a capacity of 630 MLD by opening up all 63 diffuser ports in the existing diffuser using variable orifice, 220 mm diameter ports that open up to 270 mm at peak flows. The advantage of this alternative is that higher jet velocities (and therefore better mixing) is achieved over a wide range of flows, as presented in Figure 1, while maintaining the same hydraulic capacity at peak flows. This alternative is similar to Alternative 1 in that it retains the existing infrastructure. Because Alternative 2 achieves an initial dilution ratio of 22:1, unlike Alternative 1, it does not require relaxation of the MOE 20:1 guideline.

Figure 2 Comparison of jet velocities for fixed and variable diameter diffuser ports

3.3 Alternative 3 – Tertiary Treatment This alternative is similar to Alternative 1 in that it achieves an initial dilution of 19:1 at a capacity of 630 MLD by opening up all 63 diffuser ports in the existing diffuser using fixed, 275 mm diameter ports. The added benefit of this alternative is that providing tertiary treatment limits the TP in the final effluent to a concentration of 0.15 mg/L thereby reducing the size of the mixing zone. Because the outfall would still provide an initial dilution of 19:1, it would require relaxation of the MOE’s 20:1 initial dilution requirement. In addition, tertiary treatment would not contribute to further ammonia removal in the plant and thus the size of the mixing zone for UIA would remain the same.

0

2

4

6

8

0 500 1,000 1,500 2,000 2,500

Jet V

eloc

ity (m

/s)

Flow (MLD)

Variable Port Fixed Port


7


3.4 Alternative 4 – Extend Existing Diffuser A 400 m extension to the outfall diffuser using open-cut construction techniques could include about 80 new ports (at 5 m spacing) to supplement the 63 in the existing diffuser. Due to the greater number of diffuser ports, exit velocities would be lower than in Alternative 1; however, this disadvantage would be compensated for by the longer diffuser length extended into deeper water off-shore. Using a 280 mm diameter port openings, this alternative could provide a capacity of greater than 630 MLD while achieving an initial dilution on the order of 33:1. It should be noted that the hydraulics of this alternative would be more sophisticated than a conventional diffuser due to the head losses that would occur in the 1200 mm risers used to connect the extension as well as the significant difference in riser length for ports in the existing (tunnel) and extended (open-cut) portions of the diffuser. Should this alternative be selected, ports would need to be sized to allow for balanced flow between the diffusers in the existing and extended portions of the diffuser. The technical challenge associated with achieving balanced flow is a major disadvantage of this alternative. Initial dilutions would be on the order of 33:1 and the mixing zone would extend into the far-field region.

3.5 Alternative 5 – New Outfall A new outfall would include a tunnel of around 4 meter diameter to convey 890 MLD, the ultimate capacity of the Duffin Creek WPCP. This alternative achieves an initial dilution of 76:1 at a capacity of 630 MLD by opening up 100 diffuser ports in a 700 m diffuser that extends 3000 meters offshore using fixed, 185 mm diameter ports. This initial dilution would be sufficient to achieve PWQO for both UIA and TP in the near field region and would thus not require a mixing zone that extends into the far field region. At the ultimate capacity flow of 890 MLD, port diameters would be opened up to 268 mm so as to provide sufficient hydraulic capacity to meet wet weather flows and the diffuser would achieve an initial dilution of 53:1.

4 Far Field Mixing Zones – MIKE-3 Modelling MIKE-3 modelling was performed on the five alternatives for total phosphorus and un-ionized ammonia. Table 3 provides the area of the mixing zone at the 90th percentile criterion for the baseline scenario at 520 MLD and the five alternative solutions at 630MLD. The MIKE-3 simulation results that correspond with these mixing zones can be seen in Figures 2 to 31. Overall these alternatives have similar sized or smaller mixing zones than the baseline scenario of 520MLD which has been approved in the Certificate of Approval. Table 3 - Area of the Mixing Zone for 90th percentile for key constituents

Parameter Area of the mixing zone at 90th percentile (ha) Baseline Alt. 1 Alt. 2 Alt. 3 Alt. 4 Alt. 5

TP 243 230 217 17 211 <1* UIA (summer) 4.1 5.7 5.7 5.7 <0.5* <0.5* UIA (winter) <3* 1.6 <3* 1.6 <0.5* <0.5* *Areas estimated from CORMIX results Table 4 provides the total ammonia nitrogen concentrations at the Ajax Water Intake. The peak values for all alternatives are below the Great Lakes Water Quality Agreement guideline of 0.5 mg/L.

Table 4 – Total Ammonia Nitrogen Concentration at the Ajax Water Intake Ajax Ammonia Baseline 1 2 3 4 5 Peak (mg/L) 0.134 0.134 0.150 0.134 0.150 0.248 Mean (mg/L) 0.021 0.022 0.023 0.022 0.023 0.029

8


The impact of the mixing zones on beneficial uses, as defined in the MOE Procedure B-1-5, is provided in Appendix A. 4.1 Baseline – Existing Plant at 520 MLD The mixing zones as defined by the 90th percentiles for TP and UIA in summer and winter, respectively, are presented in Figure 3, Figure 4 and Figure 5. This mixing zone illustrates the envelope within which the plume is contained 90% of the time, which is about 600 meters offshore. These figures are presented as a basis of comparison with the five alternatives. Further details of model simulation results for the baseline condition are presented in the Baseline report.

Figure 3 Baseline – Mixing zone for TP based on the 90th percentile criteria

Outfall

Ajax Water Intake


9


Figure 4 Baseline – Mixing zone for UIA based on the 90th percentile criteria – summer

Figure 5 Baseline – No mixing zone in far-field for UIA based on the 90th

percentile criteria – winter

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

10


4.2 Alternative 1 – Upgraded/Expanded Plant The mixing zone for TP in the far-field is presented in Figure 6 based on the 90th

Figure 7

percentile criteria. This mixing zone extends to the east as well as to the west due to the shifting current directions that are experienced in this area but does not impinge on the shoreline. This mixing zone shows the outside of the envelope of the most extreme movement of the plume and, like the baseline scenario, remains about 600 meters offshore. Average concentrations of TP for the simulation period are presented in demonstrating that, on average, the size of the mixing zone for TP is significantly smaller than that which is defined by the 90th

The mixing zones for UIA in summer and winter are presented in

percentile.

Figure 8 and Figure 10, respectively, based on the 90th percentile criteria. Low temperatures in winter contribute to low UIA factors (the fraction of the TAN that exists in the toxic, un-ionized form) and the result is a mixing zone that is very small. For the summer condition, the mixing zone is limited to an area immediately surrounding the outfall diffuser and is comparable in size to the zone identified for the Baseline scenario at 520 MLD. Average concentrations of UIA for summer and winter are presented in Figure 9 and Figure 11.

A time-series of the TAN concentrations at the location of the Ajax WSP intake is presented in Figure 12. These results show that average and maximum TAN, respectively 0.022 and 0.134 mg/L, are well below the Great Lakes Water Quality Agreement guideline of 0.5 mg/L.


11


Figure 6 Alternative 1 – Mixing zone for TP based on the 90th percentile criteria

Figure 7 Alternative 1 – Average concentrations of TP for April to November simulation period

<0.02 mg/L (green) <0.025 mg/L

(yellow)

>0.025 mg/L (red)

<0.015 mg/L (light blue)

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

12


Figure 8 Alternative 1 – Mixing zone for UIA in summer based on the 90th percentile

Figure 9 Alternative 1 – Average summer concentrations of UIA

>0.02 mg/L (red)

<0.02 mg/L (yellow)

<0.015 mg/L (green)


Outfall

Ajax Water Intake

Outfall

Ajax Water Intake


13


Figure 10 Alternative 1 – Mixing zone for UIA in Winter based on the 90th percentile criteria

Figure 11 Alternative 1 – Mixing zone for UIA in Winter based on the 90th percentile criteria

<0.015 mg/L (green)


Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

14


Figure 12 Alternative 1 – Total Ammonia Nitrogen at the Ajax WSP Intake (Drinking Water Standard is 0.5 mg/L)


15


4.3 Alternative 2 - TideFlex The mixing zone for TP in the far-field is presented in Figure 13 based on the 90th percentile criteria. This mixing zone extends to the east as well as to the west due to the shifting current directions that are experienced in this area but does not impinge on the shoreline. This mixing zone is about 10% smaller than in Alternative 1 and shows the outside of the envelope of the most extreme movement of the plume and, like the baseline scenario, remains about 600 meters offshore. Average concentrations of TP for the simulation period are presented in Figure 14 demonstrating that, on average, the size of the mixing zone is significantly smaller than that which is defined by the 90th percentile.

The mixing zones for UIA in summer and winter are presented in Figure 15 and Figure 17, respectively, based on the 90th

Figure 16

percentile criteria. For the summer condition, the mixing zone is very small and 45% smaller than the corresponding mixing zone in Alternative 1. For the winter condition, the mixing zone is non-existent. These results demonstrate that this alternative provides more benefit to reducing the size of the UIA than the TP mixing zone. This is because the benefit of this alternative is to provide higher port exit velocities in the near field zone; this has less influence on the TP plume which extends further into the far field. Average concentrations of UIA for summer and winter are presented in and Figure 18.

A time-series of the TAN concentrations at the location of the Ajax WSP intake is presented in Figure 19. These results show that average and maximum TAN, respectively 0.023 and 0.150 mg/L, are well below the drinking water standard of 0.5 mg/L.


Outfall

Ajax Water Intake

16



Figure 15 Alternative 2 – Mixing zone for UIA in summer based on the 90th percentile criteria

<0.025 mg/L (yellow) <0.02 mg/L

(green)

>0.025 mg/L (red)


Outfall

Ajax Water Intake

Outfall

Ajax Water Intake


17



Figure 17 Alternative 2 – No Mixing zone in far-field for UIA in winter based on the 90th percentile criteria

>0.02 mg/L (red)

<0.02 mg/L (yellow)

<0.015 mg/L (green)


Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

18


Figure 18 Alternative 2 – Average winter concentrations of UIA


<0.015 mg/L (green) <0.01 mg/L

(light blue)

Outfall

Ajax Water Intake


19


4.4 Alternative 3 – Tertiary Treatment The mixing zone for TP in the far-field is presented in Figure 20 based on the 90th percentile criteria. This mixing is about 90% smaller than the mixing zone in Alternative 1 and remains about 900 meters offshore. Since the outfall configuration for this alternative is identical to Alternative 1, this difference in the size of the mixing zone can be entirely attributed to the lower effluent TP concentration from the plant, 0.15 vs 0.5 mg/L, respectively. Average concentrations of TP for the simulation period are presented in Figure 21 demonstrating that, on average, the size of the mixing zone is significantly smaller than that which is defined by the 90th percentile.

Because the tertiary treatment that is included in Alternative 3 does not provide any additional ammonia removal, the results with respect to UIA and TAN would be identical to Alternative 1. The reader is referred to Alternative 1 for a discussion of the size of the UIA mixing zone in summer and winter and concentrations of TAN at the Ajax WSP intake.


Outfall

Ajax Water Intake

20



4.5 Alternative 4 – Extend Existing Diffuser The mixing zone for TP in the far-field is presented in Figure 22 based on the 90th percentile criteria. This mixing zone shows the outside of the envelope of the most extreme movement of the plume and remains about 300 meters offshore. The mixing zone does not impinge on the shoreline and is 11% smaller as compared to Alternative 1. Average concentrations of TP for the simulation period are presented in Figure 23 demonstrating that, on average, the size of the mixing zone is significantly smaller than that which is defined by the 90th percentile. It should be noted that the size and orientation of the mixing zone in this alternative are strongly influenced by the orientation of diffuser extension which was chosen based on results of geotechnical explorations so as to minimize construction risk.

There are no mixing zones for UIA in summer and winter as presented in Figure 24 and Figure 26, respectively, based on the 90th

Figure 25

percentile criteria. These results demonstrate that, like Alternative 2, Alternative 4 provides more benefit to reducing the size of the mixing zone for UIA than for TP. Average concentrations of UIA for summer and winter are presented in and Figure 27.



<0.015 mg/L (green)

Outfall

Ajax Water Intake


21



Figure 23 Alternative 4 – Average concentrations of TP for the April to November simulation period

<0.025 mg/L (yellow)

<0.02 mg/L (green)


Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

22


Figure 24 Alternative 4 – No mixing zone if far-field for UIA in summer based on the 90th percentile



<0.015 mg/L (green)

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake


23


Figure 26 Alternative 4 – No mixing zone in far-field for UIA in Winter based on the 90th percentile

Figure 27 Alternative 4 – Average winter concentrations of UIA

<0.01 mg/L

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

24



4.6 Alternative 5 – New Outfall As identified in Section 3, an initial dilution of 76:1 in the near field region was calculated using the CORMIX model which is greater than the dilution ratio required to achieve PWQO for TP (49:1) and UIA (less than 20:1). As such, no mixing zone in the far-field region is required for either TP or UIA. This is confirmed by the MIKE-3 results which show no mixing zones for TP and UIA (Figure 29, Figure 30 and Figure 31). Average TP and UIA concentrations for the April to November model simulation are below 0.01 mg/L for all regions areas surrounding the outfall and are not presented.



25


Figure 29 Alternative 5 – No mixing zone in far-field for TP based on the 90th percentile criteria

Figure 30 Alternative 5 – No mixing zone in far-field for UIA in Summer based on the 90th percentile criteria

Outfall

Ajax Water Intake

Outfall

Ajax Water Intake

26


Figure 31 Alternative 5 – No mixing zone in far-field for UIA in Winter based on the 90th percentile criteria

Figure 32 Alternative 5 – Total Ammonia Nitrogen at the Ajax WSP Intake (Drinking Water Standard is 0.5 mg/L

Outfall

Ajax Water Intake

27


Appendix A – MOE Procedure B-1-5, Considerations for Mixing Zones

Table 5 – Impact Evaluation Criteria – MOE Procedure B-1-5 Considerations for Mixing Zones

MOE Procedure B-1-5 Outfall EA – Evaluation Criteria Impact Assessment

In order to protect important aquatic communities (fish, invertebrates and plants) in the vicinity of mixing zones, no conditions within the mixing zone will be permitted which:

are acutely lethal to aquatic life Impacts on Water Quality The Duffin Creek WPCP has a nitrification process. The effluent unionized ammonia is non-toxic to fish.

cause irreversible responses which could result in detrimental post-exposure effects

Impacts on Water Quality The Duffin Creek WPCP has a nitrification process. The effluent unionized ammonia is non-toxic to fish.

result in bio-concentration of toxic materials which are harmful to the organism or its consumer

Impacts on Water Quality

The Duffin Creek WPCP has a low percentage of industrial wastewater. Also, the regional sewer-use bylaws control the levels of metals and other organic toxins to the plant. The primary toxic element of interest at the plant is unionized ammonia which does not bio-concentrate.

attract organisms to the mixing zones, resulting in a prolonged exposure

Impact on Nearshore and Offshore Aquatic Systems and Habitats

There are no changes in the effluent from the baseline of 520MLD that would attract organisms to the mixing zones.

create a barrier to the migration of fish or other aquatic life

Impact on Nearshore and Offshore Aquatic Systems and Habitats

There are no changes in the effluent from the baseline of 520MLD that would create a barrier to the migration of fish or other aquatic life. Also, the mixing zone is a transient area for fish; no specialized habitat has been identified in this area of the nearshore zone.

To ensure the protection of acceptable aesthetic conditions, mixing zones should not contain:

materials which form objectionable deposits (e.g. scums, oil or floating debris);

Impact on Aesthetic Conditions along the shoreline

The WPCP has treatment processes to remove scum, oil, and floating debris.

substances producing objectionable colour, odour, taste or turbidity


With a total suspended solids effluent limit of 25mg/L, the WPCP does not produce objectionable colour, odour, taste, or turbidity.

APPENDIX A – MOE PROCEDURE B-1-5, CONSIDERATIONS FOR MIXING ZONES

29


MOE Procedure B-1-5 Outfall EA – Evaluation Criteria Impact Assessment

substances which produce or contribute to the production of objectionable growths of nuisance plants and animals


No change from current aesthetic conditions is anticipated since there is no increase in TP loading to the lake from the WPCP.

substances that render the mixing zone aesthetically unacceptable


No change from current aesthetic conditions anticipated since there is no change in TP effluent limits from the baseline of 520MLD.

Mixing zones should not impinge upon existing:

municipal and other water supply intakes

Impact on the Ajax Water Supply Intake

Lake modelling demonstrates that the total ammonium levels at the intake of the Ajax Water Supply Plant meet the drinking water quality guidelines at 630MLD. The mixing zone does not interfere with the Ajax Water intake.

bathing beaches Tourism, Recreation and Other Uses of Lake and Lakefront

Effluent from the WPCP achieves E.Coli levels well below the 100 counts per 100mL, which is the recreational water quality guideline from the Ministry of Health. Prevailing plume moves in the east-west direction with minimal effect to nearshore beach and lakefront recreational uses.

important fish spawning areas Impact on Nearshore and Offshore Aquatic Systems and Habitats

Effluent mixing zone is a transient area for fish; no specialized habitat identified in this area of the nearshore zone.

Initial Mixing Initial mixing for discharge diffusers in lakes must have a minimum near field (initial mixing) ratio of 20:1.

Performance – CORMIX modelling

Alternatives 1 and 3 achieve 19:1 initial dilution at an average day flow of 630 MLD and therefore do not achieve the minimum near field initial dilution ratio of 20:1. Alternatives 2, 4, and 5 do achieve a 20:1 initial dilution.

Appendix B – Hydraulic Calculations

Alternatives 1 and 3 Parameter Units Value Total Head Loss

Outfall Shaft Water Elevation m 80.772 4.70 m High Lake Level m 76.02 Available Head m 4.752 Average Flow MLD 630 Peak Factor # 2.5 Peak Flow MLD 1575 Peak Flow m3/s 18.2 # of open ports # 63 diameter of ports m 0.275 C roughness constant n/a 90 DIFFUSER PORT REDUCER 90o

Bend Riser Entry into Riser (Tee)

Diameter m 0.275 0.275 0.457 0.411 0.411 Length m 0.000 0.500 1.000 14.900 0.000 Velocity m/s 4.87 4.87 1.76 2.18 2.18 Flowrate m3/s 0.29 0.29 0.29 0.29 0.29 K - 1.00 0.04 0.20 0.00 1.40 C roughness constant - 90 90 90 90 90 Exit Loss m 1.21 0.05 0.03 0.00 0.34 Friction Loss m 0.00 0.07 0.01 0.30 0.00 Head Loss m 1.21 0.12 0.04 0.30 0.34 Total Head Loss 2.01 m OUTFALL PIPE OUTFALL PIPE DROPSHAFT # of pipes # 1 1 Diameter m 3.048 5.490 Length m 1100 32.600 Velocity m/s 2.50 0.77 Flowrate m3/s 18.23 18.23 K - 0.00 0.04 C roughness constant - 90 90 Minor Losses m 0.00 0.00 Friction Loss m 2.69 0.00 Head Loss m 2.69 0.01 Total Head Loss 2.69 m

32


Alternatives 2 Parameter Units Value Total Head Loss




ALTERNATIVES 4

33


Alternatives 4 Parameter Units Value Total Head Loss Outfall Shaft Water Elevation m 80.772 4.68 m High Lake Level m 76.02 Available Head m 4.752 Average Flow MLD 630 Peak Factor # 2.5 Peak Flow MLD 1575 Peak Flow m3/s 18.2 # of open ports # 143 diameter of ports m 0.28 C roughness constant n/a 90 DIFFUSER PORT REDUCER 90o Bend Riser Entry into Riser (Tee) Diameter m 0.280 0.280 0.457 0.411 0.411 Length m 0.000 1.000 1.000 14.900 0.000 Velocity m/s 2.07 2.07 0.78 0.96 0.96 Flowrate m3/s 0.13 0.13 0.13 0.13 0.13 K - 1.00 0.04 0.20 0.00 1.40 C roughness constant - 90 90 90 90 90 Exit Loss m 0.22 0.01 0.01 0.00 0.07 Friction Loss m 0.00 0.03 0.00 0.06 0.00 Head Loss m 0.22 0.04 0.01 0.06 0.07 Total Head Loss 0.39 m OUTFALL PIPE OUTFALL PIPE DROPSHAFT 2-1200mm RISERS # of pipes # 1 1 2 Diameter m 3.048 5.490 1.200 Length m 1450 32.600 14.900 Velocity m/s 2.50 0.77 4.51 Flowrate m3/s 18.23 18.23 5.10 K - 0.00 0.04 0.40 C roughness constant - 90 90 90 Minor Losses m 0.00 0.00 0.41 Friction Loss m 3.54 0.00 0.32 Head Loss m 3.54 0.01 0.74 Total Head Loss 4.29 m

34


Alternative 5 Parameter Units Value Total Head Loss




APPENDIX C – CORMIX MODEL INPUTS

35


Appendix C – CORMIX Model Inputs

Note that Alternative 3 is exactly the same as Alternative 1 with respect to Diffuser configuration

Parameter Alt 1 Alt 2 Alt 4 Alt 5 Alt 5 @ 890 Ambient depth, m 10.0 10.0 10.0 15.0 15.0 Local depth, m 10.2 10.2 10.2 15.0 15.0 Ambient current speed, m/s 0.044 0.044 0.044 0.044 0.044 Manning friction 0.035 0.035 0.035 0.035 0.035 Ambient temperature, deg. C 15 21 21 21 21 Wind speed, m/s 5 5 5 5 5 Diffuser length, m 183 183 466 700 700 Distance to first diffuser port, m 1000 1000 1000 2300 2300 Distance to other diffuser port, m 1183 1183 1466 3000 3000 Gamma, deg. 90 90 90 90 90 Number of discharge openings 63 63 143 100 100 Diameter ports, m 0.275 0.219 0.280 0.185 0.268 Contraction coefficient 1 1 1 1 1 Height above the bottom, m 1 1 1 1 1 theta, deg. 30 30 30 30 30 beta, deg. 0 0 0 0 0 sigma, deg. 270 270 270 270 270 flowrate, m3/s 7.29 7.29 7.29 7.29 7.29 Discharge temperature, deg. C 17 17 17 17 17

36


Appendix D – CORMIX Model Outputs

37


Alternatives 1 and 3 CORMIX2 PREDICTION FILE: 22222222222222222222222222222222222222222222222222222222222222222222222222222 CORNELL MIXING ZONE EXPERT SYSTEM Subsystem CORMIX2: Subsystem version: Submerged Multiport Diffuser Discharges CORMIX_v.3.20_____September_1996 ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CASE DESCRIPTION Site name/label: DC^Hydraulics^Sensitivity^Analysis Design case: PF^2.5x630MLD FILE NAME: cormix\sim\qwerty .cx2 Time of Fortran run: 11/15/12--07:41:15 ENVIRONMENT PARAMETERS (metric units) Unbounded section HA = 10.00 HD = 10.20 UA = .044 F = .045 USTAR = .3287E-02 UW = 5.000 UWSTAR= .5890E-02 Uniform density environment STRCND= U RHOAM = 999.1010 DIFFUSER DISCHARGE PARAMETERS (metric units) Diffuser type: DITYPE= staged_perpendicular BANK = LEFT DISTB = 1091.50 YB1 = 1000.00 YB2 = 1183.00 LD = 183.00 NOPEN = 63 SPAC = 2.95 D0 = .275 A0 = .059 H0 = 1.00 Nozzle/port arrangement: staged GAMMA = 90.00 THETA = 30.00 SIGMA = 270.00 BETA = .00 U0 = 1.949 Q0 = 7.292 = .7292E+01 RHO0 = 998.7762 DRHO0 = .3248E+00 GP0 = .3188E-02 C0 = .1000E+01 CUNITS= ppm IPOLL = 1 KS = .0000E+00 KD = .0000E+00 FLUX VARIABLES - PER UNIT DIFFUSER LENGTH (metric units) q0 = .3985E-01 m0 = .7764E-01 j0 = .1270E-03 SIGNJ0= 1.0 Associated 2-d length scales (meters) lQ=B = .020 lM = 30.61 lm = 40.10 lmp = 99999.00 lbp = 99999.00 la = 99999.00 FLUX VARIABLES - ENTIRE DIFFUSER (metric units) Q0 = .7292E+01 M0 = .1421E+02 J0 = .2325E-01 Associated 3-d length scales (meters) LQ = 1.93 LM = 47.99 Lm = 85.67 Lb = 272.98

38


Lmp = 99999.00 Lbp = 99999.00 NON-DIMENSIONAL PARAMETERS FR0 = 241.30 FRD0 = 65.80 R = 44.28 (slot) (port/nozzle) FLOW CLASSIFICATION 222222222222222222222222222222222222222222 2 Flow class (CORMIX2) = MU6 2 2 Applicable layer depth HS = 10.20 2 222222222222222222222222222222222222222222 MIXING ZONE / TOXIC DILUTION / REGION OF INTEREST PARAMETERS C0 = .1000E+01 CUNITS= ppm NTOX = 0 NSTD = 0 REGMZ = 0 XINT = 5000.00 XMAX = 5000.00 X-Y-Z COORDINATE SYSTEM: ORIGIN is located at the bottom and the diffuser mid-point: 1091.50 m from the LEFT bank/shore. X-axis points downstream, Y-axis points to left, Z-axis points upward. NSTEP = 20 display intervals per module ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- BEGIN MOD202: DISCHARGE MODULE (STAGED DIFFUSER) Due to complex near-field motions: EQUIVALENT SLOT DIFFUSER (2-D) GEOMETRY Profile definitions: BV = Gaussian 1/e (37%) half-width, in vertical plane normal to trajectory BH = Gaussian 1/e (37%) half-width in horizontal plane normal to trajectory S = hydrodynamic centerline dilution C = centerline concentration (includes reaction effects, if any) X Y Z S C BV BH .00 91.50 1.00 1.0 .100E+01 .14 .14 END OF MOD202: DISCHARGE MODULE (STAGED DIFFUSER) ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- BEGIN MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT Because of the strong ambient current the diffuser plume of this crossflowing discharge gets RAPIDLY DEFLECTED. A near-field zone is formed that is VERTICALLY FULLY MIXED over the entire layer depth. Full mixing is achieved at a downstream distance of about

ALTERNATIVES 1 AND 3

39


five (5) layer depths. Profile definitions: BV = layer depth (vertically mixed) BH = top-hat half-width, measured horizontally in y-direction S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) X Y Z S C BV BH .00 91.50 1.00 1.0 .100E+01 .14 .14 2.55 68.94 1.20 5.0 .201E+00 .64 7.74 5.10 46.37 1.41 6.6 .151E+00 1.14 15.34 7.65 23.81 1.62 7.9 .127E+00 1.65 22.94 10.20 1.25 1.82 8.9 .112E+00 2.15 30.55 12.75 -21.32 2.02 9.9 .101E+00 2.65 38.15 15.30 -43.88 2.23 10.7 .933E-01 3.16 45.75 17.85 -66.44 2.43 11.5 .870E-01 3.66 53.35 20.40 -89.01 2.64 12.2 .819E-01 4.16 60.95 22.95 -111.57 2.85 12.9 .775E-01 4.67 68.56 25.50 -134.13 3.05 13.5 .739E-01 5.17 76.16 28.05 -156.70 3.25 14.2 .707E-01 5.67 83.76 30.60 -179.26 3.46 14.7 .679E-01 6.17 91.36 33.15 -201.82 3.66 15.3 .654E-01 6.68 98.96 35.70 -224.38 3.87 15.8 .631E-01 7.18 106.57 38.25 -246.95 4.07 16.4 .611E-01 7.68 114.17 40.80 -269.51 4.28 16.9 .593E-01 8.19 121.77 43.35 -292.07 4.48 17.3 .576E-01 8.69 129.37 45.90 -314.64 4.69 17.8 .561E-01 9.19 136.97 48.45 -337.20 4.89 18.3 .547E-01 9.70 144.58 51.00 -359.76 5.10 18.7 .534E-01 10.20 152.18 Cumulative travel time = 1159. sec END OF MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT ----------------------------------------------------------------------------- ** End of NEAR-FIELD REGION (NFR) ** ----------------------------------------------------------------------------- BEGIN MOD241: BUOYANT AMBIENT SPREADING Profile definitions: BV = top-hat thickness, measured vertically BH = top-hat half-width, measured horizontally in y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) Plume Stage 1 (not bank attached): X Y Z S C BV BH ZU ZL

40


53.55 -359.76 10.20 18.7 .534E-01 10.20 152.18 10.20 .00 200.69 -359.76 10.20 21.3 .469E-01 7.40 238.63 10.20 2.80 347.82 -359.76 10.20 23.5 .426E-01 6.25 311.01 10.20 3.95 494.96 -359.76 10.20 25.6 .390E-01 5.66 375.40 10.20 4.54 642.10 -359.76 10.20 28.0 .357E-01 5.34 434.38 10.20 4.86 789.24 -359.76 10.20 30.7 .326E-01 5.20 489.35 10.20 5.00 936.37 -359.76 10.20 33.8 .296E-01 5.17 541.21 10.20 5.03 1083.51 -359.76 10.20 37.3 .268E-01 5.23 590.54 10.20 4.97 1230.65 -359.76 10.20 41.2 .243E-01 5.36 637.79 10.20 4.84 1377.79 -359.76 10.20 45.7 .219E-01 5.54 683.28 10.20 4.66 1524.92 -359.76 10.20 50.7 .197E-01 5.77 727.25 10.20 4.43 1672.06 -359.76 10.20 56.2 .178E-01 6.05 769.91 10.20 4.15 1819.20 -359.76 10.20 62.2 .161E-01 6.36 811.41 10.20 3.84 1966.34 -359.76 10.20 68.9 .145E-01 6.70 851.87 10.20 3.50 2113.47 -359.76 10.20 76.2 .131E-01 7.08 891.40 10.20 3.12 2260.61 -359.76 10.20 84.0 .119E-01 7.49 930.09 10.20 2.71 2407.75 -359.76 10.20 92.5 .108E-01 7.92 968.02 10.20 2.28 2554.89 -359.76 10.20 101.7 .983E-02 8.38 1005.24 10.20 1.82 2702.02 -359.76 10.20 111.5 .897E-02 8.87 1041.81 10.20 1.33 2849.16 -359.76 10.20 122.0 .820E-02 9.38 1077.78 10.20 .82 2996.30 -359.76 10.20 133.2 .751E-02 9.91 1113.18 10.20 .29 Cumulative travel time = 68040. sec END OF MOD241: BUOYANT AMBIENT SPREADING ----------------------------------------------------------------------------- Bottom coordinate for FAR-FIELD is determined by average depth, ZFB = .20m ----------------------------------------------------------------------------- BEGIN MOD261: PASSIVE AMBIENT MIXING IN UNIFORM AMBIENT Vertical diffusivity (initial value) = .127E-01 m^2/s Horizontal diffusivity (initial value) = .173E+02 m^2/s Profile definitions: BV = Gaussian s.d.*sqrt(pi/2) (46%) thickness, measured vertically = or equal to layer depth, if fully mixed BH = Gaussian s.d.*sqrt(pi/2) (46%) half-width, measured horizontally in Y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic centerline dilution C = centerline concentration (includes reaction effects, if any) Plume Stage 1 (not bank attached): X Y Z S C BV BH ZU ZL 2996.30 -359.76 10.20 133.2 .751E-02 9.91 1113.18 10.20 .29 Plume interacts with BOTTOM. The passive diffusion plume becomes VERTICALLY FULLY MIXED within this prediction interval.

ALTERNATIVES 1 AND 3

41


3025.39 -359.76 10.20 136.3 .734E-02 10.00 1129.37 10.20 .20 3054.49 -359.76 10.20 138.3 .723E-02 10.00 1145.63 10.20 .20 3083.59 -359.76 10.20 140.2 .713E-02 10.00 1161.98 10.20 .20 3112.68 -359.76 10.20 142.2 .703E-02 10.00 1178.39 10.20 .20 3141.78 -359.76 10.20 144.2 .693E-02 10.00 1194.89 10.20 .20 3170.87 -359.76 10.20 146.2 .684E-02 10.00 1211.46 10.20 .20 3199.97 -359.76 10.20 148.2 .675E-02 10.00 1228.11 10.20 .20 3229.07 -359.76 10.20 150.2 .666E-02 10.00 1244.83 10.20 .20 3258.16 -359.76 10.20 152.3 .657E-02 10.00 1261.63 10.20 .20 3287.26 -359.76 10.20 154.3 .648E-02 10.00 1278.50 10.20 .20 3316.35 -359.76 10.20 156.3 .640E-02 10.00 1295.45 10.20 .20 3345.45 -359.76 10.20 158.4 .631E-02 10.00 1312.47 10.20 .20 3374.55 -359.76 10.20 160.5 .623E-02 10.00 1329.57 10.20 .20 3403.64 -359.76 10.20 162.5 .615E-02 10.00 1346.74 10.20 .20 3432.74 -359.76 10.20 164.6 .607E-02 10.00 1363.98 10.20 .20 3461.83 -359.76 10.20 166.7 .600E-02 10.00 1381.30 10.20 .20 3490.93 -359.76 10.20 168.8 .592E-02 10.00 1398.69 10.20 .20 3520.03 -359.76 10.20 170.9 .585E-02 10.00 1416.15 10.20 .20 3549.12 -359.76 10.20 173.0 .578E-02 10.00 1433.68 10.20 .20 3578.22 -359.76 10.20 175.1 .571E-02 10.00 1451.28 10.20 .20 Cumulative travel time = 81265. sec ----------------------------------------------------------------------------- Plume Stage 2 (bank attached): X Y Z S C BV BH ZU ZL 3578.22 1091.50 10.20 175.1 .571E-02 10.00 2902.57 10.20 .20 3649.31 1091.50 10.20 178.4 .560E-02 10.00 2957.04 10.20 .20 3720.40 1091.50 10.20 181.7 .550E-02 10.00 3011.85 10.20 .20 3791.48 1091.50 10.20 185.1 .540E-02 10.00 3066.99 10.20 .20 3862.57 1091.50 10.20 188.4 .531E-02 10.00 3122.47 10.20 .20 3933.66 1091.50 10.20 191.8 .521E-02 10.00 3178.27 10.20 .20 4004.75 1091.50 10.20 195.2 .512E-02 10.00 3234.41 10.20 .20 4075.84 1091.50 10.20 198.6 .504E-02 10.00 3290.87 10.20 .20 4146.93 1091.50 10.20 202.0 .495E-02 10.00 3347.65 10.20 .20 4218.02 1091.50 10.20 205.5 .487E-02 10.00 3404.76 10.20 .20 4289.11 1091.50 10.20 208.9 .479E-02 10.00 3462.19 10.20 .20 4360.20 1091.50 10.20 212.4 .471E-02 10.00 3519.94 10.20 .20 4431.29 1091.50 10.20 215.9 .463E-02 10.00 3578.01 10.20 .20 4502.38 1091.50 10.20 219.4 .456E-02 10.00 3636.39 10.20 .20 4573.47 1091.50 10.20 223.0 .448E-02 10.00 3695.09 10.20 .20 4644.56 1091.50 10.20 226.5 .441E-02 10.00 3754.10 10.20 .20 4715.65 1091.50 10.20 230.1 .435E-02 10.00 3813.42 10.20 .20 4786.73 1091.50 10.20 233.7 .428E-02 10.00 3873.05 10.20 .20 4857.82 1091.50 10.20 237.3 .421E-02 10.00 3932.98 10.20 .20 4928.91 1091.50 10.20 241.0 .415E-02 10.00 3993.23 10.20 .20 5000.00 1091.50 10.20 244.6 .409E-02 10.00 4053.78 10.20 .20 Cumulative travel time = 113578. sec

42


Simulation limit based on maximum specified distance = 5000.00 m. This is the REGION OF INTEREST limitation. END OF MOD261: PASSIVE AMBIENT MIXING IN UNIFORM AMBIENT ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CORMIX2: Submerged Multiport Diffuser Discharges End of Prediction File 22222222222222222222222222222222222222222222222222222222222222222222222222222

ALTERNATIVE 2

43


Alternative 2 CORMIX2 PREDICTION FILE: 22222222222222222222222222222222222222222222222222222222222222222222222222222 CORNELL MIXING ZONE EXPERT SYSTEM Subsystem CORMIX2: Subsystem version: Submerged Multiport Diffuser Discharges CORMIX_v.3.20_____September_1996 ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CASE DESCRIPTION Site name/label: DC^Hydraulics^Sensitivity^Analysis Design case: PF^2.5x630MLD FILE NAME: cormix\sim\qwerty .cx2 Time of Fortran run: 11/15/12--07:54:47 ENVIRONMENT PARAMETERS (metric units) Unbounded section HA = 10.00 HD = 10.20 UA = .044 F = .045 USTAR = .3287E-02 UW = 5.000 UWSTAR= .5890E-02 Uniform density environment STRCND= U RHOAM = 997.9935 DIFFUSER DISCHARGE PARAMETERS (metric units) Diffuser type: DITYPE= staged_perpendicular BANK = LEFT DISTB = 1091.50 YB1 = 1000.00 YB2 = 1183.00 LD = 183.00 NOPEN = 63 SPAC = 2.95 D0 = .206 A0 = .033 H0 = 1.00 Nozzle/port arrangement: staged GAMMA = 90.00 THETA = 30.00 SIGMA = 270.00 BETA = .00 U0 = 3.464 Q0 = 7.292 = .7292E+01 RHO0 = 998.7762 DRHO0 =-.7827E+00 GP0 =-.7691E-02 C0 = .1000E+01 CUNITS= ppm IPOLL = 1 KS = .0000E+00 KD = .0000E+00 FLUX VARIABLES - PER UNIT DIFFUSER LENGTH (metric units) q0 = .3985E-01 m0 = .1380E+00 j0 =-.3064E-03 SIGNJ0= -1.0 Associated 2-d length scales (meters) lQ=B = .012 lM = 30.26 lm = 71.30 lmp = 99999.00 lbp = 99999.00 la = 99999.00 FLUX VARIABLES - ENTIRE DIFFUSER (metric units) Q0 = .7292E+01 M0 = .2526E+02 J0 =-.5608E-01 Associated 3-d length scales (meters) LQ = 1.45 LM = 47.58 Lm = 114.23 Lb = 658.34 Lmp = 99999.00 Lbp = 99999.00 NON-DIMENSIONAL PARAMETERS

44


FR0 = 368.32 FRD0 = 86.98 R = 78.73 (slot) (port/nozzle) FLOW CLASSIFICATION 222222222222222222222222222222222222222222 2 Flow class (CORMIX2) = MNU11 2 2 Applicable layer depth HS = 10.20 2 222222222222222222222222222222222222222222 MIXING ZONE / TOXIC DILUTION / REGION OF INTEREST PARAMETERS C0 = .1000E+01 CUNITS= ppm NTOX = 0 NSTD = 0 REGMZ = 0 XINT = 5000.00 XMAX = 5000.00 X-Y-Z COORDINATE SYSTEM: ORIGIN is located at the bottom and the diffuser mid-point: 1091.50 m from the LEFT bank/shore. X-axis points downstream, Y-axis points to left, Z-axis points upward. NSTEP = 20 display intervals per module ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- BEGIN MOD202: DISCHARGE MODULE (STAGED DIFFUSER) Due to complex near-field motions: EQUIVALENT SLOT DIFFUSER (2-D) GEOMETRY Profile definitions: BV = Gaussian 1/e (37%) half-width, in vertical plane normal to trajectory BH = Gaussian 1/e (37%) half-width in horizontal plane normal to trajectory S = hydrodynamic centerline dilution C = centerline concentration (includes reaction effects, if any) X Y Z S C BV BH .00 91.50 1.00 1.0 .100E+01 .10 .10 END OF MOD202: DISCHARGE MODULE (STAGED DIFFUSER) ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- BEGIN MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT Because of the strong ambient current the diffuser plume of this crossflowing discharge gets RAPIDLY DEFLECTED. A near-field zone is formed that is VERTICALLY FULLY MIXED over the entire layer depth. Full mixing is achieved at a downstream distance of about five (5) layer depths. Profile definitions:

ALTERNATIVE 2

45


BV = layer depth (vertically mixed) BH = top-hat half-width, measured horizontally in y-direction S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) X Y Z S C BV BH .00 91.50 1.00 1.0 .100E+01 .10 .10 2.55 54.95 .95 5.9 .169E+00 .61 9.41 5.10 18.39 .90 7.9 .126E+00 1.11 18.71 7.65 -18.16 .85 9.5 .105E+00 1.62 28.01 10.20 -54.72 .80 10.8 .926E-01 2.12 37.31 12.75 -91.27 .75 12.0 .836E-01 2.63 46.61 15.30 -127.83 .70 13.0 .769E-01 3.13 55.92 17.85 -164.38 .65 14.0 .716E-01 3.64 65.22 20.40 -200.93 .60 14.9 .673E-01 4.14 74.52 22.95 -237.49 .55 15.7 .637E-01 4.65 83.82 25.50 -274.04 .50 16.5 .606E-01 5.15 93.13 28.05 -310.60 .45 17.3 .580E-01 5.66 102.43 30.60 -347.15 .40 18.0 .556E-01 6.16 111.73 33.15 -383.71 .35 18.7 .536E-01 6.67 121.03 35.70 -420.26 .30 19.3 .517E-01 7.17 130.34 38.25 -456.81 .25 20.0 .501E-01 7.68 139.64 40.80 -493.37 .20 20.6 .485E-01 8.18 148.94 43.35 -529.92 .15 21.2 .472E-01 8.69 158.24 45.90 -566.48 .10 21.8 .459E-01 9.19 167.54 48.45 -603.03 .05 22.4 .447E-01 9.70 176.85 51.00 -639.59 .00 22.9 .436E-01 10.20 186.15 Cumulative travel time = 1159. sec END OF MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT ----------------------------------------------------------------------------- ** End of NEAR-FIELD REGION (NFR) ** ----------------------------------------------------------------------------- BEGIN MOD241: BUOYANT AMBIENT SPREADING Profile definitions: BV = top-hat thickness, measured vertically BH = top-hat half-width, measured horizontally in y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) Plume Stage 1 (not bank attached): X Y Z S C BV BH ZU ZL 53.55 -639.59 .00 22.9 .436E-01 10.20 186.15 10.20 .00 245.21 -639.59 .00 27.0 .371E-01 6.63 337.00 6.63 .00 436.86 -639.59 .00 29.9 .335E-01 5.41 457.76 5.41 .00

46


628.52 -639.59 .00 32.7 .305E-01 4.82 563.15 4.82 .00 820.17 -639.59 .00 35.8 .279E-01 4.51 658.55 4.51 .00 1011.83 -639.59 .00 39.3 .254E-01 4.36 746.76 4.36 .00 1203.48 -639.59 .00 43.3 .231E-01 4.32 829.48 4.32 .00 1395.14 -639.59 .00 47.8 .209E-01 4.36 907.84 4.36 .00 1586.80 -639.59 .00 52.9 .189E-01 4.46 982.64 4.46 .00 1778.45 -639.59 .00 58.6 .171E-01 4.61 1054.49 4.61 .00 1970.11 -639.59 .00 65.1 .154E-01 4.80 1123.83 4.80 .00 2161.76 -639.59 .00 72.2 .138E-01 5.02 1191.01 5.02 .00 2353.42 -639.59 .00 80.1 .125E-01 5.28 1256.32 5.28 .00 2545.08 -639.59 .00 88.8 .113E-01 5.57 1319.97 5.57 .00 2736.73 -639.59 .00 98.2 .102E-01 5.89 1382.15 5.89 .00 2928.39 -639.59 .00 108.5 .922E-02 6.23 1443.01 6.23 .00 3120.04 -639.59 .00 119.5 .836E-02 6.59 1502.67 6.59 .00 3311.70 -639.59 .00 131.5 .760E-02 6.98 1561.24 6.98 .00 3503.35 -639.59 .00 144.3 .693E-02 7.39 1618.79 7.39 .00 3695.01 -639.59 .00 158.0 .633E-02 7.82 1675.42 7.82 .00 3886.67 -639.59 .00 172.7 .579E-02 8.26 1731.19 8.26 .00 Cumulative travel time = 88275. sec ----------------------------------------------------------------------------- Plume is ATTACHED to LEFT bank/shore. Plume width is now determined from LEFT bank/shore. Plume Stage 2 (bank attached): X Y Z S C BV BH ZU ZL 3886.67 1091.50 .00 172.7 .579E-02 8.26 3462.17 8.26 .00 3923.76 1091.50 .00 175.5 .570E-02 8.37 3472.28 8.37 .00 3960.84 1091.50 .00 178.3 .561E-02 8.48 3482.38 8.48 .00 3997.93 1091.50 .00 181.1 .552E-02 8.59 3492.49 8.59 .00 4035.02 1091.50 .00 183.9 .544E-02 8.70 3502.58 8.70 .00 4072.11 1091.50 .00 186.8 .535E-02 8.81 3512.68 8.81 .00 4109.20 1091.50 .00 189.6 .527E-02 8.92 3522.77 8.92 .00 4146.29 1091.50 .00 192.5 .519E-02 9.03 3532.85 9.03 .00 4183.38 1091.50 .00 195.4 .512E-02 9.14 3542.93 9.14 .00 4220.47 1091.50 .00 198.4 .504E-02 9.25 3553.01 9.25 .00 4257.56 1091.50 .00 201.3 .497E-02 9.36 3563.08 9.36 .00 4294.65 1091.50 .00 204.3 .490E-02 9.47 3573.14 9.47 .00 4331.74 1091.50 .00 207.2 .483E-02 9.58 3583.20 9.58 .00 4368.83 1091.50 .00 210.2 .476E-02 9.70 3593.26 9.70 .00 4405.92 1091.50 .00 213.3 .469E-02 9.81 3603.31 9.81 .00 4443.01 1091.50 .00 216.3 .462E-02 9.92 3613.35 9.92 .00 4480.10 1091.50 .00 219.3 .456E-02 10.03 3623.39 10.03 .00 4517.19 1091.50 .00 222.4 .450E-02 10.14 3633.42 10.14 .00 4554.28 1091.50 .00 225.5 .444E-02 10.20 3643.45 10.20 .00 4591.37 1091.50 .00 228.6 .437E-02 10.20 3653.47 10.20 .00 4628.46 1091.50 .00 231.7 .432E-02 10.20 3663.48 10.20 .00 Cumulative travel time = 105134. sec

ALTERNATIVE 2

47


END OF MOD241: BUOYANT AMBIENT SPREADING ----------------------------------------------------------------------------- Due to the attachment or proximity of the plume to the bottom, the bottom coordinate for the FAR-FIELD differs from the ambient depth, ZFB = 0 m. In a subsequent analysis set "depth at discharge" equal to "ambient depth". ----------------------------------------------------------------------------- BEGIN MOD261: PASSIVE AMBIENT MIXING IN UNIFORM AMBIENT Vertical diffusivity (initial value) = .127E-01 m^2/s Horizontal diffusivity (initial value) = .847E+02 m^2/s The passive diffusion plume is VERTICALLY FULLY MIXED at beginning of region. Profile definitions: BV = Gaussian s.d.*sqrt(pi/2) (46%) thickness, measured vertically = or equal to layer depth, if fully mixed BH = Gaussian s.d.*sqrt(pi/2) (46%) half-width, measured horizontally in Y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic centerline dilution C = centerline concentration (includes reaction effects, if any) Plume Stage 2 (bank attached): X Y Z S C BV BH ZU ZL 4628.46 1091.50 .00 231.7 .432E-02 10.20 3663.48 10.20 .00 4647.03 1091.50 .00 232.7 .430E-02 10.20 3678.83 10.20 .00 4665.61 1091.50 .00 233.6 .428E-02 10.20 3694.20 10.20 .00 4684.19 1091.50 .00 234.6 .426E-02 10.20 3709.59 10.20 .00 4702.77 1091.50 .00 235.6 .424E-02 10.20 3725.00 10.20 .00 4721.34 1091.50 .00 236.6 .423E-02 10.20 3740.43 10.20 .00 4739.92 1091.50 .00 237.5 .421E-02 10.20 3755.88 10.20 .00 4758.50 1091.50 .00 238.5 .419E-02 10.20 3771.35 10.20 .00 4777.07 1091.50 .00 239.5 .418E-02 10.20 3786.85 10.20 .00 4795.65 1091.50 .00 240.5 .416E-02 10.20 3802.37 10.20 .00 4814.23 1091.50 .00 241.5 .414E-02 10.20 3817.90 10.20 .00 4832.81 1091.50 .00 242.4 .412E-02 10.20 3833.46 10.20 .00 4851.38 1091.50 .00 243.4 .411E-02 10.20 3849.04 10.20 .00 4869.96 1091.50 .00 244.4 .409E-02 10.20 3864.64 10.20 .00 4888.54 1091.50 .00 245.4 .407E-02 10.20 3880.27 10.20 .00 4907.11 1091.50 .00 246.4 .406E-02 10.20 3895.91 10.20 .00 4925.69 1091.50 .00 247.4 .404E-02 10.20 3911.57 10.20 .00 4944.27 1091.50 .00 248.4 .403E-02 10.20 3927.26 10.20 .00 4962.85 1091.50 .00 249.4 .401E-02 10.20 3942.96 10.20 .00 4981.42 1091.50 .00 250.4 .399E-02 10.20 3958.69 10.20 .00 5000.00 1091.50 .00 251.4 .398E-02 10.20 3974.44 10.20 .00 Cumulative travel time = 113578. sec

48



ALTERNATIVE 4

49


Alternative 4 CORMIX2 PREDICTION FILE: 22222222222222222222222222222222222222222222222222222222222222222222222222222 CORNELL MIXING ZONE EXPERT SYSTEM Subsystem CORMIX2: Subsystem version: Submerged Multiport Diffuser Discharges CORMIX_v.3.20_____September_1996 ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CASE DESCRIPTION Site name/label: DC^Hydraulics^Sensitivity^Analysis Design case: PF^2.5x630MLD FILE NAME: cormix\sim\qwerty .cx2 Time of Fortran run: 11/15/12--08:03:05 ENVIRONMENT PARAMETERS (metric units) Unbounded section HA = 10.00 HD = 10.20 UA = .044 F = .045 USTAR = .3287E-02 UW = 5.000 UWSTAR= .5890E-02 Uniform density environment STRCND= U RHOAM = 997.9935 DIFFUSER DISCHARGE PARAMETERS (metric units) Diffuser type: DITYPE= staged_perpendicular BANK = LEFT DISTB = 1233.00 YB1 = 1000.00 YB2 = 1466.00 LD = 466.00 NOPEN = 143 SPAC = 3.28 D0 = .275 A0 = .059 H0 = 1.00 Nozzle/port arrangement: staged GAMMA = 90.00 THETA = 30.00 SIGMA = 270.00 BETA = .00 U0 = .858 Q0 = 7.292 = .7292E+01 RHO0 = 998.7762 DRHO0 =-.7827E+00 GP0 =-.7691E-02 C0 = .1000E+01 CUNITS= ppm IPOLL = 1 KS = .0000E+00 KD = .0000E+00 FLUX VARIABLES - PER UNIT DIFFUSER LENGTH (metric units) q0 = .1565E-01 m0 = .1343E-01 j0 =-.1203E-03 SIGNJ0= -1.0 Associated 2-d length scales (meters) lQ=B = .018 lM = 5.50 lm = 6.94 lmp = 99999.00 lbp = 99999.00 la = 99999.00 FLUX VARIABLES - ENTIRE DIFFUSER (metric units) Q0 = .7292E+01 M0 = .6260E+01 J0 =-.5608E-01 Associated 3-d length scales (meters) LQ = 2.91 LM = 16.71 Lm = 56.86 Lb = 658.34 Lmp = 99999.00 Lbp = 99999.00 NON-DIMENSIONAL PARAMETERS

50



ALTERNATIVE 4

51


BV = layer depth (vertically mixed) BH = top-hat half-width, measured horizontally in y-direction S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) X Y Z S C BV BH .00 233.00 1.00 1.0 .100E+01 .14 .14 2.55 213.43 .95 8.1 .123E+00 .64 13.45 5.10 193.85 .90 11.1 .905E-01 1.14 26.76 7.65 174.28 .85 13.3 .751E-01 1.65 40.06 10.20 154.70 .80 15.2 .657E-01 2.15 53.37 12.75 135.13 .75 16.9 .592E-01 2.65 66.68 15.30 115.55 .70 18.4 .543E-01 3.16 79.99 17.85 95.98 .65 19.8 .505E-01 3.66 93.30 20.40 76.40 .60 21.1 .474E-01 4.16 106.61 22.95 56.83 .55 22.3 .448E-01 4.67 119.92 25.50 37.25 .50 23.5 .426E-01 5.17 133.23 28.05 17.68 .45 24.6 .407E-01 5.67 146.54 30.60 -1.90 .40 25.6 .390E-01 6.18 159.84 33.15 -21.47 .35 26.6 .376E-01 6.68 173.15 35.70 -41.05 .30 27.6 .362E-01 7.18 186.46 38.25 -60.62 .25 28.5 .351E-01 7.68 199.77 40.80 -80.20 .20 29.4 .340E-01 8.19 213.08 43.35 -99.77 .15 30.3 .330E-01 8.69 226.39 45.90 -119.35 .10 31.2 .321E-01 9.19 239.70 48.45 -138.92 .05 32.0 .313E-01 9.70 253.01 51.00 -158.50 .00 32.8 .305E-01 10.20 266.32 Cumulative travel time = 1159. sec END OF MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT ----------------------------------------------------------------------------- ** End of NEAR-FIELD REGION (NFR) ** ----------------------------------------------------------------------------- BEGIN MOD241: BUOYANT AMBIENT SPREADING Profile definitions: BV = top-hat thickness, measured vertically BH = top-hat half-width, measured horizontally in y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) Plume Stage 1 (not bank attached): X Y Z S C BV BH ZU ZL 53.55 -158.50 .00 32.8 .305E-01 10.20 266.32 10.20 .00 183.33 -158.50 .00 35.7 .280E-01 8.22 359.45 8.22 .00 313.11 -158.50 .00 38.1 .263E-01 7.15 441.27 7.15 .00

52


442.89 -158.50 .00 40.3 .248E-01 6.48 515.67 6.48 .00 572.67 -158.50 .00 42.6 .235E-01 6.04 584.66 6.04 .00 702.45 -158.50 .00 45.0 .222E-01 5.74 649.46 5.74 .00 832.23 -158.50 .00 47.5 .211E-01 5.53 710.88 5.53 .00 962.01 -158.50 .00 50.1 .199E-01 5.40 769.49 5.40 .00 1091.79 -158.50 .00 53.0 .189E-01 5.32 825.72 5.32 .00 1221.57 -158.50 .00 56.2 .178E-01 5.29 879.90 5.29 .00 1351.35 -158.50 .00 59.6 .168E-01 5.30 932.30 5.30 .00 1481.13 -158.50 .00 63.3 .158E-01 5.33 983.13 5.33 .00 1610.91 -158.50 .00 67.2 .149E-01 5.40 1032.57 5.40 .00 1740.69 -158.50 .00 71.5 .140E-01 5.48 1080.76 5.48 .00 1870.47 -158.50 .00 76.1 .131E-01 5.59 1127.83 5.59 .00 2000.25 -158.50 .00 81.0 .123E-01 5.72 1173.88 5.72 .00 2130.03 -158.50 .00 86.2 .116E-01 5.86 1219.01 5.86 .00 2259.81 -158.50 .00 91.8 .109E-01 6.02 1263.28 6.02 .00 2389.59 -158.50 .00 97.7 .102E-01 6.20 1306.78 6.20 .00 2519.38 -158.50 .00 104.0 .961E-02 6.39 1349.55 6.39 .00 2649.16 -158.50 .00 110.7 .903E-02 6.59 1391.65 6.59 .00 Cumulative travel time = 60150. sec ----------------------------------------------------------------------------- Plume is ATTACHED to LEFT bank/shore. Plume width is now determined from LEFT bank/shore. Plume Stage 2 (bank attached): X Y Z S C BV BH ZU ZL 2649.16 1233.00 .00 110.7 .903E-02 6.59 2783.00 6.59 .00 2737.55 1233.00 .00 115.1 .869E-02 6.79 2809.81 6.79 .00 2825.94 1233.00 .00 119.6 .836E-02 6.98 2836.56 6.98 .00 2914.34 1233.00 .00 124.1 .806E-02 7.18 2863.23 7.18 .00 3002.73 1233.00 .00 128.8 .776E-02 7.39 2889.83 7.39 .00 3091.13 1233.00 .00 133.5 .749E-02 7.59 2916.36 7.59 .00 3179.52 1233.00 .00 138.4 .723E-02 7.79 2942.82 7.79 .00 3267.92 1233.00 .00 143.3 .698E-02 8.00 2969.21 8.00 .00 3356.31 1233.00 .00 148.3 .674E-02 8.20 2995.52 8.20 .00 3444.71 1233.00 .00 153.4 .652E-02 8.41 3021.76 8.41 .00 3533.10 1233.00 .00 158.6 .630E-02 8.62 3047.92 8.62 .00 3621.49 1233.00 .00 163.9 .610E-02 8.84 3074.02 8.84 .00 3709.89 1233.00 .00 169.3 .591E-02 9.05 3100.04 9.05 .00 3798.28 1233.00 .00 174.8 .572E-02 9.26 3125.99 9.26 .00 3886.68 1233.00 .00 180.3 .555E-02 9.48 3151.87 9.48 .00 3975.07 1233.00 .00 186.0 .538E-02 9.70 3177.68 9.70 .00 4063.47 1233.00 .00 191.8 .522E-02 9.92 3203.41 9.92 .00 4151.86 1233.00 .00 197.6 .506E-02 10.14 3229.08 10.14 .00 4240.26 1233.00 .00 203.5 .491E-02 10.20 3254.68 10.20 .00 4328.65 1233.00 .00 209.6 .477E-02 10.20 3280.20 10.20 .00 4417.05 1233.00 .00 215.7 .464E-02 10.20 3305.66 10.20 .00 Cumulative travel time = 100329. sec

ALTERNATIVE 4

53


END OF MOD241: BUOYANT AMBIENT SPREADING ----------------------------------------------------------------------------- Due to the attachment or proximity of the plume to the bottom, the bottom coordinate for the FAR-FIELD differs from the ambient depth, ZFB = 0 m. In a subsequent analysis set "depth at discharge" equal to "ambient depth". ----------------------------------------------------------------------------- BEGIN MOD261: PASSIVE AMBIENT MIXING IN UNIFORM AMBIENT Vertical diffusivity (initial value) = .127E-01 m^2/s Horizontal diffusivity (initial value) = .739E+02 m^2/s The passive diffusion plume is VERTICALLY FULLY MIXED at beginning of region. Profile definitions: BV = Gaussian s.d.*sqrt(pi/2) (46%) thickness, measured vertically = or equal to layer depth, if fully mixed BH = Gaussian s.d.*sqrt(pi/2) (46%) half-width, measured horizontally in Y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic centerline dilution C = centerline concentration (includes reaction effects, if any) Plume Stage 2 (bank attached): X Y Z S C BV BH ZU ZL 4417.04 1233.00 .00 215.7 .464E-02 10.20 3305.66 10.20 .00 4446.19 1233.00 .00 217.2 .460E-02 10.20 3328.93 10.20 .00 4475.34 1233.00 .00 218.8 .457E-02 10.20 3352.27 10.20 .00 4504.49 1233.00 .00 220.3 .454E-02 10.20 3375.66 10.20 .00 4533.63 1233.00 .00 221.8 .451E-02 10.20 3399.10 10.20 .00 4562.78 1233.00 .00 223.3 .448E-02 10.20 3422.59 10.20 .00 4591.93 1233.00 .00 224.9 .445E-02 10.20 3446.14 10.20 .00 4621.08 1233.00 .00 226.4 .442E-02 10.20 3469.75 10.20 .00 4650.23 1233.00 .00 228.0 .439E-02 10.20 3493.40 10.20 .00 4679.37 1233.00 .00 229.5 .436E-02 10.20 3517.11 10.20 .00 4708.52 1233.00 .00 231.1 .433E-02 10.20 3540.88 10.20 .00 4737.67 1233.00 .00 232.6 .430E-02 10.20 3564.69 10.20 .00 4766.82 1233.00 .00 234.2 .427E-02 10.20 3588.56 10.20 .00 4795.97 1233.00 .00 235.7 .424E-02 10.20 3612.49 10.20 .00 4825.11 1233.00 .00 237.3 .421E-02 10.20 3636.46 10.20 .00 4854.26 1233.00 .00 238.9 .419E-02 10.20 3660.49 10.20 .00 4883.41 1233.00 .00 240.4 .416E-02 10.20 3684.57 10.20 .00 4912.56 1233.00 .00 242.0 .413E-02 10.20 3708.71 10.20 .00 4941.71 1233.00 .00 243.6 .411E-02 10.20 3732.90 10.20 .00 4970.85 1233.00 .00 245.2 .408E-02 10.20 3757.13 10.20 .00 5000.00 1233.00 .00 246.8 .405E-02 10.20 3781.43 10.20 .00 Cumulative travel time = 113578. sec

54



ALTERNATIVE 5

55


Alternative 5 CORMIX2 PREDICTION FILE: 22222222222222222222222222222222222222222222222222222222222222222222222222222 CORNELL MIXING ZONE EXPERT SYSTEM Subsystem CORMIX2: Subsystem version: Submerged Multiport Diffuser Discharges CORMIX_v.3.20_____September_1996 ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CASE DESCRIPTION Site name/label: DC^Hydraulics^Sensitivity^Analysis Design case: PF^2.5x630MLD FILE NAME: cormix\sim\qwerty .cx2 Time of Fortran run: 11/15/12--08:11:36 ENVIRONMENT PARAMETERS (metric units) Unbounded section HA = 15.00 HD = 15.00 UA = .044 F = .039 USTAR = .3072E-02 UW = 5.000 UWSTAR= .5890E-02 Uniform density environment STRCND= U RHOAM = 997.9935 DIFFUSER DISCHARGE PARAMETERS (metric units) Diffuser type: DITYPE= staged_perpendicular BANK = LEFT DISTB = 2650.00 YB1 = 2300.00 YB2 = 3000.00 LD = 700.00 NOPEN = 100 SPAC = 7.07 D0 = .185 A0 = .027 H0 = 1.00 Nozzle/port arrangement: staged GAMMA = 90.00 THETA = 30.00 SIGMA = 270.00 BETA = .00 U0 = 2.713 Q0 = 7.292 = .7292E+01 RHO0 = 998.7762 DRHO0 =-.7827E+00 GP0 =-.7691E-02 C0 = .1000E+01 CUNITS= ppm IPOLL = 1 KS = .0000E+00 KD = .0000E+00 FLUX VARIABLES - PER UNIT DIFFUSER LENGTH (metric units) q0 = .1042E-01 m0 = .2826E-01 j0 =-.8011E-04 SIGNJ0= -1.0 Associated 2-d length scales (meters) lQ=B = .004 lM = 15.16 lm = 14.60 lmp = 99999.00 lbp = 99999.00 la = 99999.00 FLUX VARIABLES - ENTIRE DIFFUSER (metric units) Q0 = .7292E+01 M0 = .1978E+02 J0 =-.5608E-01 Associated 3-d length scales (meters) LQ = 1.64 LM = 39.61 Lm = 101.08 Lb = 658.34 Lmp = 99999.00 Lbp = 99999.00 NON-DIMENSIONAL PARAMETERS

56



ALTERNATIVE 5

57


BV = layer depth (vertically mixed) BH = top-hat half-width, measured horizontally in y-direction S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) X Y Z S C BV BH .00 350.00 1.00 1.0 .100E+01 .09 .09 3.75 315.47 .95 17.8 .563E-01 .84 21.07 7.50 280.94 .90 24.7 .405E-01 1.58 42.05 11.25 246.41 .85 30.0 .333E-01 2.33 63.03 15.00 211.89 .80 34.5 .290E-01 3.07 84.01 18.75 177.36 .75 38.5 .260E-01 3.82 104.99 22.50 142.83 .70 42.1 .238E-01 4.56 125.97 26.25 108.30 .65 45.4 .220E-01 5.31 146.95 30.00 73.77 .60 48.4 .207E-01 6.06 167.93 33.75 39.24 .55 51.3 .195E-01 6.80 188.91 37.50 4.71 .50 54.0 .185E-01 7.55 209.89 41.25 -29.82 .45 56.6 .177E-01 8.29 230.87 45.00 -64.34 .40 59.1 .169E-01 9.04 251.85 48.75 -98.87 .35 61.4 .163E-01 9.78 272.83 52.50 -133.40 .30 63.7 .157E-01 10.53 293.81 56.25 -167.93 .25 65.9 .152E-01 11.27 314.79 60.00 -202.46 .20 68.1 .147E-01 12.02 335.77 63.75 -236.99 .15 70.1 .143E-01 12.76 356.75 67.50 -271.52 .10 72.1 .139E-01 13.51 377.73 71.25 -306.05 .05 74.1 .135E-01 14.25 398.71 75.00 -340.57 .00 76.0 .132E-01 15.00 419.69 Cumulative travel time = 1705. sec END OF MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT ----------------------------------------------------------------------------- ** End of NEAR-FIELD REGION (NFR) ** ----------------------------------------------------------------------------- BEGIN MOD241: BUOYANT AMBIENT SPREADING Profile definitions: BV = top-hat thickness, measured vertically BH = top-hat half-width, measured horizontally in y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) Plume Stage 1 (not bank attached): X Y Z S C BV BH ZU ZL 78.75 -340.57 .00 76.0 .132E-01 15.00 419.69 15.00 .00 324.81 -340.57 .00 83.2 .120E-01 12.29 560.67 12.29 .00 570.88 -340.57 .00 89.8 .111E-01 10.86 684.98 10.86 .00

58


816.94 -340.57 .00 96.5 .104E-01 10.02 798.26 10.02 .00 1063.00 -340.57 .00 103.8 .963E-02 9.52 903.47 9.52 .00 1309.06 -340.57 .00 111.8 .894E-02 9.24 1002.44 9.24 .00 1555.13 -340.57 .00 120.8 .828E-02 9.13 1096.38 9.13 .00 1801.19 -340.57 .00 130.7 .765E-02 9.13 1186.15 9.13 .00 2047.25 -340.57 .00 141.8 .705E-02 9.23 1272.42 9.23 .00 2293.31 -340.57 .00 154.1 .649E-02 9.42 1355.68 9.42 .00 2539.38 -340.57 .00 167.5 .597E-02 9.67 1436.33 9.67 .00 2785.44 -340.57 .00 182.3 .548E-02 9.97 1514.68 9.97 .00 3031.50 -340.57 .00 198.5 .504E-02 10.34 1590.99 10.34 .00 3277.56 -340.57 .00 216.0 .463E-02 10.75 1665.48 10.75 .00 3523.63 -340.57 .00 235.0 .426E-02 11.20 1738.33 11.20 .00 3769.69 -340.57 .00 255.5 .391E-02 11.70 1809.68 11.70 .00 4015.75 -340.57 .00 277.4 .360E-02 12.23 1879.67 12.23 .00 4261.81 -340.57 .00 301.0 .332E-02 12.80 1948.40 12.80 .00 4507.88 -340.57 .00 326.1 .307E-02 13.40 2015.98 13.40 .00 4753.94 -340.57 .00 352.8 .283E-02 14.04 2082.48 14.04 .00 5000.00 -340.57 .00 381.2 .262E-02 14.71 2147.98 14.71 .00 Cumulative travel time = 113551. sec Simulation limit based on maximum specified distance = 5000.00 m. This is the REGION OF INTEREST limitation. END OF MOD241: BUOYANT AMBIENT SPREADING ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CORMIX2: Submerged Multiport Diffuser Discharges End of Prediction File 22222222222222222222222222222222222222222222222222222222222222222222222222222

ALTERNATIVE 5 AT THE ULTIMATE CAPACITY OF 890 MLD

59


Alternative 5 at the Ultimate Capacity of 890 MLD CORMIX2 PREDICTION FILE: 22222222222222222222222222222222222222222222222222222222222222222222222222222 CORNELL MIXING ZONE EXPERT SYSTEM Subsystem CORMIX2: Subsystem version: Submerged Multiport Diffuser Discharges CORMIX_v.3.20_____September_1996 ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CASE DESCRIPTION Site name/label: DC^Hydraulics^Sensitivity^Analysis Design case: PF^2.5x630MLD FILE NAME: cormix\sim\qwerty .cx2 Time of Fortran run: 11/16/12--10:14:46 ENVIRONMENT PARAMETERS (metric units) Unbounded section HA = 15.00 HD = 15.00 UA = .044 F = .039 USTAR = .3072E-02 UW = 5.000 UWSTAR= .5890E-02 Uniform density environment STRCND= U RHOAM = 997.9935 DIFFUSER DISCHARGE PARAMETERS (metric units) Diffuser type: DITYPE= staged_perpendicular BANK = LEFT DISTB = 2650.00 YB1 = 2300.00 YB2 = 3000.00 LD = 700.00 NOPEN = 100 SPAC = 7.07 D0 = .268 A0 = .056 H0 = 1.00 Nozzle/port arrangement: staged GAMMA = 90.00 THETA = 30.00 SIGMA = 270.00 BETA = .00 U0 = 1.826 Q0 = 10.301 = .1030E+02 RHO0 = 998.7762 DRHO0 =-.7827E+00 GP0 =-.7691E-02 C0 = .1000E+01 CUNITS= ppm IPOLL = 1 KS = .0000E+00 KD = .0000E+00 FLUX VARIABLES - PER UNIT DIFFUSER LENGTH (metric units) q0 = .1472E-01 m0 = .2687E-01 j0 =-.1132E-03 SIGNJ0= -1.0 Associated 2-d length scales (meters) lQ=B = .008 lM = 11.46 lm = 13.88 lmp = 99999.00 lbp = 99999.00 la = 99999.00 FLUX VARIABLES - ENTIRE DIFFUSER (metric units) Q0 = .1030E+02 M0 = .1881E+02 J0 =-.7922E-01 Associated 3-d length scales (meters) LQ = 2.38 LM = 32.09 Lm = 98.57 Lb = 930.04 Lmp = 99999.00 Lbp = 99999.00 NON-DIMENSIONAL PARAMETERS

60



ALTERNATIVE 5 AT THE ULTIMATE CAPACITY OF 890 MLD

61


BV = layer depth (vertically mixed) BH = top-hat half-width, measured horizontally in y-direction S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) X Y Z S C BV BH .00 350.00 1.00 1.0 .100E+01 .13 .13 3.75 316.31 .95 12.7 .787E-01 .88 20.95 7.50 282.61 .90 17.6 .569E-01 1.62 41.78 11.25 248.92 .85 21.3 .470E-01 2.36 62.60 15.00 215.23 .80 24.4 .409E-01 3.11 83.42 18.75 181.53 .75 27.2 .368E-01 3.85 104.24 22.50 147.84 .70 29.7 .337E-01 4.59 125.06 26.25 114.15 .65 32.0 .313E-01 5.34 145.88 30.00 80.45 .60 34.1 .293E-01 6.08 166.70 33.75 46.76 .55 36.1 .277E-01 6.82 187.52 37.50 13.06 .50 38.0 .263E-01 7.57 208.34 41.25 -20.63 .45 39.8 .251E-01 8.31 229.16 45.00 -54.32 .40 41.6 .241E-01 9.05 249.98 48.75 -88.02 .35 43.2 .231E-01 9.80 270.80 52.50 -121.71 .30 44.8 .223E-01 10.54 291.62 56.25 -155.40 .25 46.4 .216E-01 11.28 312.45 60.00 -189.10 .20 47.8 .209E-01 12.03 333.27 63.75 -222.79 .15 49.3 .203E-01 12.77 354.09 67.50 -256.48 .10 50.7 .197E-01 13.51 374.91 71.25 -290.18 .05 52.1 .192E-01 14.26 395.73 75.00 -323.87 .00 53.4 .187E-01 15.00 416.55 Cumulative travel time = 1705. sec END OF MOD275: STAGED PERPENDICULAR DIFFUSER IN STRONG CURRENT ----------------------------------------------------------------------------- ** End of NEAR-FIELD REGION (NFR) ** ----------------------------------------------------------------------------- BEGIN MOD241: BUOYANT AMBIENT SPREADING Profile definitions: BV = top-hat thickness, measured vertically BH = top-hat half-width, measured horizontally in y-direction ZU = upper plume boundary (Z-coordinate) ZL = lower plume boundary (Z-coordinate) S = hydrodynamic average (bulk) dilution C = average (bulk) concentration (includes reaction effects, if any) Plume Stage 1 (not bank attached): X Y Z S C BV BH ZU ZL 78.75 -323.87 .00 53.4 .187E-01 15.00 416.55 15.00 .00 324.81 -323.87 .00 58.8 .170E-01 11.82 582.50 11.82 .00 570.88 -323.87 .00 63.5 .158E-01 10.23 726.39 10.23 .00

62


816.94 -323.87 .00 68.0 .147E-01 9.30 856.31 9.30 .00 1063.00 -323.87 .00 72.8 .137E-01 8.73 976.27 8.73 .00 1309.06 -323.87 .00 77.9 .128E-01 8.38 1088.61 8.38 .00 1555.13 -323.87 .00 83.6 .120E-01 8.19 1194.88 8.19 .00 1801.19 -323.87 .00 89.8 .111E-01 8.11 1296.16 8.11 .00 2047.25 -323.87 .00 96.7 .103E-01 8.13 1393.26 8.13 .00 2293.31 -323.87 .00 104.3 .958E-02 8.22 1486.79 8.22 .00 2539.38 -323.87 .00 112.7 .887E-02 8.36 1577.24 8.36 .00 2785.44 -323.87 .00 121.9 .821E-02 8.57 1664.99 8.57 .00 3031.50 -323.87 .00 131.8 .759E-02 8.82 1750.36 8.82 .00 3277.56 -323.87 .00 142.6 .701E-02 9.11 1833.62 9.11 .00 3523.63 -323.87 .00 154.3 .648E-02 9.43 1914.97 9.43 .00 3769.69 -323.87 .00 166.9 .599E-02 9.80 1994.61 9.80 .00 4015.75 -323.87 .00 180.5 .554E-02 10.19 2072.68 10.19 .00 4261.81 -323.87 .00 194.9 .513E-02 10.62 2149.33 10.62 .00 4507.88 -323.87 .00 210.4 .475E-02 11.07 2224.65 11.07 .00 4753.94 -323.87 .00 226.9 .441E-02 11.55 2298.76 11.55 .00 5000.00 -323.87 .00 244.3 .409E-02 12.06 2371.74 12.06 .00 Cumulative travel time = 113551. sec Simulation limit based on maximum specified distance = 5000.00 m. This is the REGION OF INTEREST limitation. END OF MOD241: BUOYANT AMBIENT SPREADING ----------------------------------------------------------------------------- ----------------------------------------------------------------------------- CORMIX2: Submerged Multiport Diffuser Discharges End of Prediction File 22222222222222222222222222222222222222222222222222222222222222222222222222222

technical memorandum tm2 - durham

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