East Prince Waste Management Facility Leachate Treatment System
Final Report 032640.01
Prepared for:
Island Waste Management Corporation
East Prince Waste Management Facility Leachate Treatment System
Preliminary Design Study
June 2005
ISO 9001 Registered Company Contents
Chapter 1 Introduction ...... 1
1.1 Background ...... 1
Chapter 2 Leachate Characterization...... 2
2.1 General...... 2 2.1.1 Leachate Generation ...... 2 2.1.2 Leachate Composition ...... 5
Chapter 3 Treatment Requirements...... 10
3.1 Effluent Discharge Limits...... 10
3.2 Treatment Process Selection ...... 12 3.2.1 Secondary Treatment ...... 12 3.2.2 Tertiary Treatment ...... 15 3.2.3 Effluent Discharge ...... 18
Chapter 4 Preliminary Design Description ...... 21
4.1 Site Conditions...... 21
4.2 Collection System ...... 21
4.3 Treatment System ...... 22
4.4 Treatment System Performance ...... 24 4.4.1 Biodegradable Organics and Nutrients ...... 24 4.4.2 Heavy Metals ...... 25 4.4.3 Organic Priority Pollutants ...... 25 4.4.4 Pathogens...... 25 4.4.5 Effluent Characteristics...... 25
CBCL Limited Consulting Engineers Contents i
Chapter 5 Intermediate Receiving Water Study ...... 27
5.1 Background ...... 27
5.2 Preliminary Flow Assessment...... 29
5.3 Background Water Quality Assessment...... 30
5.4 Dilution Assessment ...... 33 5.4.1 Near-Field ...... 34 5.4.2 Far-Field Flow and Water Quality Modelling 35 5.4.3 Modeled Impact on Water Quality...... 38
Chapter 6 Cost Estimates ...... 41
6.1 Capital Costs ...... 41
6.2 Operation & Maintenance Costs ...... 41
Appendices
A Geotechnical Report from Jacques Whitford
B Supporting Figures for Receiving Water Study
CBCL Limited Consulting Engineers Contents ii
Chapter 1 Introduction
1.1 Background The East Prince Waste Management Facility (EPWMF) began accepting waste in December of 1994 as an integral part of the Wastewatch program initiated by the province of Prince Edward Island. The facility is located in Wellington Corner, PEI and includes both a composting facility and a second-generation inorganic landfill. The EPWMF landfill covers a total area of 8.1 hectares, which is divided into six phases. These phases are subsequently divided into 3-4 sub cells to minimize the landfill area that is actively producing leachate. Three phases of the landfill have been opened and all sub cells are accepting waste and actively producing leachate. The three phases cover an area of approximately 4.9 ha or 60% of the site. Phase IV of the landfill is under construction and is scheduled to begin receiving waste in the fall of 2005. The ultimate volume of the landfill is estimated at approximately 750,000 m3.
The EPWMF currently places approximately 25,000 tonnes per year (68 tonnes per day) of inorganic waste into the cell. In terms of volume, approximately 200,000 m3 of waste has been placed since the opening of the landfill. The leachate generated in each phase is currently collected in a dedicated internal sump and then pumped from the sump, over the landfill sidewall to a common 90 m3 double walled fibreglass underground storage tank. This leachate is then hauled by tanker truck to the Humpty Dumpty Wastewater Treatment Plant in Slemon Park. Increasing volumes of leachate have resulted in this practice becoming prohibitively expensive.
In 1997 a study was performed by CBCL Limited to examine other options for leachate treatment throughout the design life of the landfill. The study concluded that although the leachate produced at the EPWMF is of lower organic strength than typical mixed waste leachate produced by municipal solid waste landfills, the leachate still contains an organic fraction that is biodegradable and can be treated effectively with standard methods of treatment. Therefore, in November of 2003, CBCL Limited was retained to perform a preliminary design study to further define the type and cost of treatment.
CBCL Limited Consulting Engineers Introduction 1 Chapter 2 Leachate Characterization
2.1 General In order to evaluate the suitability of various treatment options, the leachate quantity and composition for the remaining landfill life must be determined. This exercise was performed using existing data on waste generation, landfill volume, landfill operating practices, and leachate quality and generation that was supplied by Island Waste Management Corporation.
2.1.1 Leachate Generation Leachate generation rate and composition will ultimately determine the size of the treatment facility required. Leachate generation has been estimated by extrapolating existing leachate production based on future landfill operation. Figure 2.1 depicts monthly leachate generation and open landfill area from the opening of the landfill in 1996 to the present. This figure shows the wide variability in monthly leachate flows typical of landfill operations.
6000 6
5000 5
/month) 4000 4 3
3000 3
2000 2 Landfill Open Area (Ha) Leachate Production (m 1000 1
0 0 Jul-96 Jul-97 Jul-98 Jul-99 Jul-00 Jul-01 Jul-02 Jul-03 Jul-04 Jan-96 Jan-97 Jan-98 Jan-99 Jan-00 Jan-01 Jan-02 Jan-03 Jan-04
Leachate Production Landfill Open Area
Figure 2.1 Monthly Leachate Production and Landfill Open Area
Figure 2.2 depicts the same data presented on a yearly basis. This figure shows a clear relationship between then amount of landfill area open and leachate generation. The pattern showing rapid increases in leachate
CBCL Limited Consulting Engineers Leachate Characterization 2 production followed by gradual decreases is a result of the field capacity of the waste placed in the landfill. When the cell is first opened more leachate is generated because less waste is available to absorb any moisture that enters the cell. As the depth of waste in the cell increases the field capacity of the waste is utilized to absorb moisture until the waste is fully saturated and cannot absorb any more excess water. This pattern will result in maximum leachate production being achieved immediately following the opening of the last sub cell of the landfill.
30000 6
25000 5 /yr) 3 20000 4
15000 3
10000 2 Landfill Open Area (Ha) Leachate Production (m Leachate Production
5000 1
0 0 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005
Leachate Production Landfill Open Area Figure 2.2 Yearly Leachate Production and Landfill Open Area
Providing filling practices remain consistent with current operating procedures, landfill open area can be extrapolated until the entire 12 ha site is open. In the same manner, peak leachate production can be established assuming new cells produce leachate at similar rates to existing cells. Figure 2.3 illustrates this approach. Utilizing this approach, peak leachate production of approximately 35,000 m3/yr will occur around 2017. This does not represent the end of the landfills useful life as waste will continue to be placed in increasing depths after all subcells have been opened. Estimation of the life of the landfill has not been performed, as it does not have any bearing on the design of leachate treatment facilities.
CBCL Limited Consulting Engineers Leachate Characterization 3
40000 12.0
35000 10.5
30000 9.0 /yr) 3
25000 7.5
20000 6.0
15000 4.5 Landfill Open Area (Ha) 10000 3.0 Leachate Production (m
5000 1.5
0 0.0 1995 1997 1999 2001 2003 2005 2007 2009 2011 2013 2015 2017
Leachate Production Landfill Open Area Linear (Leachate Production) Linear (Landfill Open Area) Figure 2.3 Peak Yearly Leachate Production
A comparison of monthly leachate production rates to average yearly production rates results in a peak month to yearly average ratio of approximately 3 to 1. This value has been utilized to estimate a future peak monthly flow rate for the treatment facility. Peak daily flows can be equalized somewhat by allowing leachate levels in the landfill to increase during periods of high leachate production. Currently, peak daily flows are dependant upon how much leachate can be practically removed from the site by tanker truck when leachate levels within the fill become too high. With a flow through treatment system, leachate will be discharged on a more consistent basis, thereby reducing the peak daily flow by better utilizing storage capacity within the cells. Therefore, a peak day to peak month ratio of 2.5 to 1 was utilized to calculate a peak daily flow.
The peak hourly leachate flow will be utilized to size conduits to and from the leachate treatment site. This flow will result if all leachate sump pumps operate continuously. Existing pump capacities for the three open cells range from 110 to 320 L/min with a total pumping rate of 540 L/min. Assuming large capacity pumps are installed in the remaining sumps, the peak pumping capacity will be 1,500 L/min.
All of the data presented in the figures is for an uncapped landfill. If the landfill is capped following the accumulation of waste to the landfill
CBCL Limited Consulting Engineers Leachate Characterization 4 design depth, leachate production will decrease substantially. However, the evaluation of the impact of the leachate, as well as the design of any new facilities, will be based upon the peak yearly leachate production rate and associated peak day and peak month flows. The design flows are tabulated in Table 2.1 below. These are based on a peak average yearly leachate production of 40,000 m3/yr that is slightly conservative when compared to the computed values described above.
Table 2.1 Leachate Generation Parameter Value Average Yearly Flow 40,000 m3/yr (110 m3/d) Peak Monthly Flow 330 m3/d Peak Daily Flow 825 m3/d Peak Hourly Flow 2,160 m3/d
2.1.2 Leachate Composition The chemical composition of leachate will vary greatly depending upon the type of waste landfilled and the age of then landfill. Typical parameters of concern include physical, biological, organic, and inorganic constituents. Predictions regarding the chemical composition of the leachate produced at the EPWMF were made utilizing existing data collected during the past three years of operation. The leachate data from previous years of operation was not utilized for determining the average leachate composition because leachate characteristics were still stabilizing and very little ammonia had been generated.
Figures 2.4 and 2.5 present a number of organic and inorganic parameters (excluding heavy metals) for the past three years data. Figures 2.6 through 2.9 present metals concentrations for the same years. These figures demonstrate that although highly variable, it does not appear as if any of the constituents are exhibiting either strongly increasing or decreasing trends and as such average leachate characteristics for this period should be sufficient for the design of leachate treatment facilities. Average leachate composition is presented in Table 2.2 for various metals, organic and inorganic parameters.
The data contained in Table 2.2 charaterize a relatively low strength leachate with a BOD/COD ratio of approximately 0.25. This ratio suggests that the leachate is moderately biodegradable will be amenable to biological treatment. The leachate also contains ammonia nitrogen at a concentration that will require reduction prior to discharge. The metals data is also typical of landfill leachates with naturally occurring metals such as iron, manganese, and aluminum occurring in much higher concentrations than other heavy metals that would be required to be solubilized from materials in the fill.
CBCL Limited Consulting Engineers Leachate Characterization 5
3500
3000
2500
2000
1500
Concentration (mg/L) 1000
500
0 Jul-01 Jul-02 Apr-01 Oct-01 Apr-02 Jan-01 Jan-02 Jun-03 Jun-04 Mar-03 Mar-04 Dec-02 Dec-03 Dec-04 Sep-02 Sep-03 Sep-04
BOD COD
Figure 2.4 Leachate BOD & COD
500
450
400
350
300
250
200
Concentration (mg/L) 150
100
50
0 Jul-01 Jul-02 Apr-01 Oct-01 Apr-02 Jun-04 Jan-01 Jan-02 Jun-03 Mar-04 Mar-03 Dec-04 Dec-03 Dec-02 Sep-04 Sep-03 Sep-02
TKN NH3 TSS
Figure 2.5 Leachate Nitrogen & TSS
CBCL Limited Consulting Engineers Leachate Characterization 6
1750 35000
1500 30000
1250 25000
1000 20000
750 15000
500 10000 (ug/L) Fe Concentration Zn & Al Concentration (ug/L) Zn & Al Concentration
250 5000
0 0 Jul-01 Jul-02 Apr-01 Oct-01 Apr-02 Jan-01 Jan-02 Jun-03 Jun-04 Mar-03 Mar-04 Dec-02 Dec-03 Dec-04 Sep-02 Sep-03 Sep-04
Zn Al Fe
Figure 2.6 Leachate Metals (0-35 000 ug/L)
100
90
80
70
60
50
40
Concentration (ug/L) 30
20
10
0 Jul-01 Jul-02 Apr-01 Oct-01 Apr-02 Jun-04 Jan-01 Jan-02 Jun-03 Mar-04 Mar-03 Dec-04 Dec-03 Dec-02 Sep-04 Sep-03 Sep-02
Cr Ni Cu
Figure 2.7 Leachate Metals (0 – 100 ug/L)
CBCL Limited Consulting Engineers Leachate Characterization 7
40
35
30
25
20
15 Concentration (ug/L) 10
5
0 Jul-01 Jul-02 Apr-01 Oct-01 Apr-02 Jan-01 Jan-02 Jun-03 Jun-04 Mar-03 Mar-04 Dec-02 Dec-03 Dec-04 Sep-02 Sep-03 Sep-04
Pb As Se Mo
Figure 2.8 Leachate Metals (0 – 40 ug/L)
3
2.5
2
1.5
1 Concentration (ug/L)
0.5
0 Jul-01 Jul-02 Apr-01 Oct-01 Apr-02 Jun-04 Jan-01 Jan-02 Jun-03 Mar-04 Mar-03 Dec-04 Dec-03 Dec-02 Sep-04 Sep-03 Sep-02
Cd Sn
Figure 2.9 Leachate Metals (0 – 3 ug/L)
CBCL Limited Consulting Engineers Leachate Characterization 8
Table 2.2 Leachate Composition Parameter Unit Minimum Maximum Average Metals Aluminium ug/L 70 512 210 Antimony ug/L 1.4 14.3 4.6 Arsenic ug/L 7 21 12.8 Barium ug/L 137.0 472 288 Beryllium ug/L 0.1 0.5 0.3 Bismuth ug/L 0.4 20 9.0 Boron ug/L 549 6270 3234 Cadmium ug/L 0.2 1.1 0.6 Total Chromium ug/L 15 76 43.7 Cobalt ug/L 1 6.2 3.6 Copper ug/L 2 49 10.0 Iron ug/L 1100 30800 11136 Lead ug/L 0.5 35 3.8 Lithium ug/L 2.7 47.4 21.5 Magnesium mg/L 7.2 136 75.2 Manganese ug/L 1600 17000 9856 Mercury ug/L 0.08 0.08 0.1 Molybdenum ug/L 0.5 20.6 4.5 Nickel ug/L 17 57 37 Selenium ug/L 5 31 13 Silver ug/L 0.1 0.1 0.1 Thallium ug/L 1.6 1.6 1.6 Tin ug/L 0.5 2.4 1.2 Vanadium ug/L 10 45 27 Zinc ug/L 24 531 134 Organics Benzene ug/L 0.2 4.4 1.5 Toluene ug/L 0.3 240 25 Ethyl Benzene ug/L 0.2 63 15 Total Phenols mg/L 0.01 1.8 0.3 Miscellaneous BOD mg/L 6 1500 189 COD mg/L 250 2980 776 TSS mg/L 12 477 59 Ammonia mg/L 32 268 144 TKN mg/L 43 285 167 Phosphorus mg/L 0.02 5.44 2.10 Potassium mg/L 18.7 397 215 Calcium mg/L 51 642 337 Chloride mg/L 321 1640 841 pH unitless 6.8 8.1 7.3 Sodium mg/L 49.3 1180 635 Sulfate mg/L 8 217 70 Fecal Coliforms MPN/100 mL 500 2100 1300 Alkalinity mg/L as Ca CO3 1760 3120 2000 Hardness mg/L as Ca CO3 161 2065 1172 nr - not regulated; nm - not measured; nd - not detected
CBCL Limited Consulting Engineers Leachate Characterization 9 Chapter 3 Treatment Requirements
3.1 Effluent Discharge Limits The treatment of leachate can be challenging due to the wide variability in both composition and volume that can occur both seasonally and over a more extended period of time. Discharge requirements for leachate treatment plants are not readily available as regulated limits, such as municipal wastewater treatment plant discharge limits. In many cases, water quality based limits are developed for specific receiving streams under site specific conditions.
Developing water quality based effluent limits requires setting instream guidelines and comparing predicted wastewater discharges to the instream guidelines. Instream guidelines are typically based upon a combination of the Canadian Water Quality Guidelines and USEPA Water Quality criteria. Provided the effluent discharge is not expected to exceed the instream guideline, these limits become the discharge parameter. However, where exceedence is anticipated wasteload allocation modelling is utilized to estimate the maximum effluent load that may be allowed, understanding that a limited mixing zone will be necessary for dilution of effluent to instream guidelines.
A review of the potential leachate characteristics as compared to the discharge parameters indicates that a number of parameters will require some degree of removal, depending upon where the end-of-pipe limits are set. Although it is ultimately the responsibility of the regulatory authority to set the discharge limits, we can make some assumptions that will allow us to predict discharge limits and evaluate various treatment processes in anticipation of these limits. Instream guidelines will be based upon the following sources of information:
• Canadian Water Quality Guidelines (CWQG) for the protection of Freshwater Aquatic Life; • Canadian Water Quality Guidelines (CWQG) for the protection of Marine Aquatic Life; • USEPA Water Quality Criteria – Freshwater Aquatic Life (used in the absence of the above CWQG criteria for specific parameters). • Background water quality as published in the 1999 PEI Water Quality Interpretive Report.
A comparison of the raw leachate characteristics to various Guidelines in presented in Table 3.1, below.
CBCL Limited Consulting Engineers Treatment Requirements 10 Table 3.1 Comparison of Raw Leachate to Various Guidelines
Parameter Unit Raw PEI CCME CCME USEPA Leachate Background Marine Freshwater Water Quality Water Quality Guideline Guideline Criteria Metals Aluminum ug/L 210 150 nr 5 - 100 750 Antimony ug/L 4.6 nm nr nr nr Arsenic ug/L 12.8 1.4 12.5 5 340 Barium ug/L 288 104 nr nr nr Beryllium ug/L 0.3 3.16 nr nr nr Bismuth ug/L 9.0 nm nr nr nr Boron ug/L 3234 nm nr nr nr Cadmium ug/L 0.6 0.02 0.12 0.017 4.3 Total Chromium ug/L 43.7 0.36 nr nr nr Cobalt ug/L 3.6 0.14 nr nr nr Copper ug/L 10.0 0.71 nr 2 - 4 13 Iron ug/L 11136 257.1 nr 300 1000.0 Lead ug/L 3.8 0.14 nr 1- 7 65 Lithium ug/L 21.5 1.12 nr nr nr Magnesium mg/L 75.2 6.9 nr nr nr Manganese ug/L 9856 28.3 nr nr nr Mercury ug/L 0.1 0.06 nr 0.1 1.4 Molybdenum ug/L 4.5 0.03 nr 73 nr Nickel ug/L 37 0.11 nr 25 - 150 470 Selenium ug/L 13 0.08 nr 1 nr Silver ug/L 0.1 nm nr 0.1 3.4 Thallium ug/L 1.6 nm nr 0.8 nr Tin ug/L 1.2 nm nr nr nr Vanadium ug/L 27 2.91 nr nr nr Zinc ug/L 134 1.94 nr 30 120 Organics Benzene ug/L 1.5 nm 110.0 370 nr Toluene ug/L 25 nm 215.0 2 nr Ethyl Benzene ug/L 15 nm 25.0 90 nr Total Phenols mg/L 0.3 nm nr 0.004 nr Miscellaneous BOD mg/L 189 nm nr nr nr COD mg/L 776 nm nr nr nr TSS mg/L 59 Background + 5 nm nr nr mg/L Ammonia mg/L 144 nm nr 0.019 nr TKN mg/L 167 nm nr nr nr Phosphorus mg/L 2.10 nm nr nr nr Potassium mg/L 215 1.3 nr nr nr Calcium mg/L 337 21.9 nr nr nr Chloride mg/L 841 12.1 nr nr nr pH unitless 7.3 7 - 8.7 6.5 - 9.0 6.5 - 9.0 Sodium mg/L 635 6.2 nr nr nr Sulfate mg/L 70 6.5 nr nr nr Fecal Coliforms MPN/100 mL 1300 nm nr nr nr Alkalinity mg/L as Ca CO3 2000 nm nr nr nr Hardness mg/L as Ca CO3 1172 67.9 nr nr nr nr - not regulated; nm - not measured; nd - not detected
CBCL Limited Consulting Engineers Treatment Requirements 11 3.2 Treatment Process Selection The data presented in Table 3.1 indicate that the selected treatment process will be required to remove BOD, TSS, ammonia, and various metals. A number of treatment processes typically utilized for leachate treatment are listed in Table 3.2. These processes include preliminary, primary, secondary, and tertiary treatment processes.
Table 3.2 Typical Leachate Treatment Processes
Treatment Process Treatment Primary Use Additional Type benefits Equalization Preliminary Reducing flow variability to Reduces variability downstream treatment in leachate units. strength. Neutralization Preliminary pH adjustment prior to Not significant clarification for metals removal Filtration / Membrane Tertiary TSS reduction BOD/COD Filtration reduction Mechanical Biological Secondary BOD/COD/TSS and Metals reduction Treatment ammonia reduction Lagooning Secondary BOD/COD/TSS reduction Metals reduction Constructed Wetlands Tertiary BOD/COD/TSS and Metals reduction nitrogen reduction Membrane Tertiary BOD/COD/TSS and Metals reduction BioReactors ammonia reduction Peat Filters Tertiary BOD/COD/TSS and Metals reduction ammonia reduction
To meet the anticipated treatment requirement, tertiary treatment will be required. Therefore, each candidate process will require a minimum of secondary and tertiary treatment component. Only two secondary treatment processes are listed, mechanical biological treatment and lagooning. Therefore, the two candidate treatment processes will utilize these as their secondary treatment process components.
3.2.1 Secondary Treatment As the selection of the secondary treatment option may influence the types of tertiary treatment that are applicable, a secondary treatment option will be compared first. As described above, two secondary treatment options will be evaluated, mechanical biological treatment and aerated stabilization basins.
CBCL Limited Consulting Engineers Treatment Requirements 12 Mechanical Biological Treatment Many forms of mechanical biological treatment exist, most of which can be classified as either suspended growth or attached growth systems. Suspended growth systems utilize aeration and mixing to keep microorganisms in suspension and achieve a relatively high concentration of these microorganisms (biomass) through the recycle of biological solids. Attached growth systems provide a surface (medium) on which the microbial layer can grow and expose this surface to wastewater for adsorption of organic material and to the atmosphere and/or artificial aeration for oxygen. A listing of specific secondary treatment processes and the category to which they belong is presented in Table 3.3.
Table 3.3 Mechanical Biological Treatment Processes Process Type Modification Suspended Growth Conventional Activated Sludge Extended Aeration Contact Stabilization Pure Oxygen Activated Sludge Sequencing Batch Reactor (SBR) Deep Shaft Oxidation Ditch Membrane Bioreactor Attached Growth Rotating Biological Contactor (RBC) Trickling Filter Biological Filter Biological Aerated Filter (BAF)
Of the processes above, sequencing batch reactors (SBR’s) have been selected as the favoured mechanical treatment process for this application. The SBR process involves a fill-and-draw complete mix reactor in which both steps of aeration and clarification occur. Settling is permitted when aeration is turned off and a decanter device is used to withdraw supernatant. Discrete cycles are used during prescribed, programmable time intervals, and all biomass remains inn the reactor during all cycles.
The treatment cycles include: • Fill - raw leachate fed to the reactor. • React – mixing and aeration of reactor contents. • Settle – quiescent settling and separation of biomass from the treated leachate. • Decant – withdrawal of treated leachate from the reactor. • Idle – removal of waste sludge from the reactor.
Some reported advantages of SBR operation include:
CBCL Limited Consulting Engineers Treatment Requirements 13 • Elimination of a secondary clarifier and return activated sludge pumping equipment. • High tolerance for peak flows and shock loading. • Avoidance of biomass washout during peak flows. • Clarification under ideal quiescent conditions, and • Process flexibility to control sludge bulking.
However, even with their ability to treat highly variable flows and loads, flow equalization is still required to reduce the volume of tankage required. In addition to the requirement for flow equalization, inhibition due to heavy metals concentration can be a concern for biological leachate treatment. Inhibitory concentrations for nitrification processes are compared to leachate concentrations in Table 3.4.
Table 3.4 Heavy Metal Inhibition Concentrations Metal Inhibitory Leachate Concentration Concentration (mg/L) (mg/L) Cadmium 0.01 - 15 0.0002 – 0.001 Copper 4 - 150 0.002 – 0.05 Chromium 10 - 118 0.02 – 0.08 Lead 0.5 - 20 0.0005 – 0.01 Mercury 1 - 150 bdl Nickel 0.1 - 10 0.02 – 0.06 Zinc 10 0.02 – 0.5 bdl – below detection limits
As the measured leachate concentrations are below the concentrations shown to be inhibitory, no specific metals removal pre-treatment has been included. However, it is likely that some metals removal will be realized in the flow equalization process that will further protect the biological system from influent metals toxicity.
Aerated Stabilization Basin Aerated stabilization basin treatment systems utilize naturally occurring biological processes to remove BOD and nitrogen, and settling to remove TSS. Although these ponds can be designed as non-aerated stabilization basins or mechanically aerated stabilization basins, the leachate characteristics, treatment requirements, and site conditions favour the aerated stabilization basin option.
Aerated stabilization basins are ponds with gently sloping sides and typical depths of three to four meters deep. These basins are mechanically aerated with diffused aeration to provide the oxygen requirements for carbon removal and nitrification, which are typically 1.0 – 1.5 kg of oxygen per kg of BOD removed and 4.6 kg of oxygen per kg of ammonia nitrified.
CBCL Limited Consulting Engineers Treatment Requirements 14 Aerated stabilization basins are completely or partially mixed. Due to the high strength and potential toxicity associated with landfill leachates, completely mixed lagoons are favoured for this application. Therefore, as settling will not occur within the completely mixed basin, a settling basin or non-aerated stabilization pond is required for solids removal. The stabilization basin will also provide additional BOD and NH3 reduction.
Aerobic stabilization basins are required to prevent seepage of untreated wastewater into the surrounding subsoil and therefore are required to either be constructed in clay type soils, which minimize percolation, or be installed with an imported clay or geomembrane liner. Due to the large volumes required for this process, flow equalization is not a concern.
Table 3.5 provides a general comparison of the two secondary treatment options.
Table 3.5 Comparison of Secondary Treatment Options Criteria Mechanical Stabilization Basins Treatment Effluent Quality Secondary Secondary Capital Cost Similar for both Similar for both Area Requirements 0.1 ha 1.0 ha Operating Cost High Low Process Reliability Subject to upset Dependable Operating Complexity High Low
The secondary processes have very different physical and operating characteristics, while achieving similar treatment efficiencies. The main differences between these two processes are the reliability and low operational complexity of the stabilization basin option. Therefore, provided the required land base is available, the stabilization basin opting is preferred and will be utilized as the basis for preliminary design.
3.2.2 Tertiary Treatment Tertiary treatment includes the removal of solids and nutrients to below secondary levels. Of the processes listed in Table 3.2, the tertiary treatment options most applicable to this application include: Constructed wetlands, Sand Filters, Peat Filters
These systems are further described below.
CBCL Limited Consulting Engineers Treatment Requirements 15 Wetland Treatment Constructed wetlands can be a cost-effective method of providing tertiary treatment. These treatment systems are inundated land areas with water depths typically less than 600 mm that support the growth of emergent plants such as cattail, bulrush, reeds, and sedges. The vegetation provides surface for the attachment of bacterial films, aids in the filtration and adsorption of wastewater constituents, transfers oxygen into the water column, and controls the growth of algae by restricting the penetration of sunlight.
Although plant uptake is an important consideration in contaminant removal, and in particular nutrient removal, it is only one of many active removal mechanisms in the wetland environment. Removal mechanisms have been classified as physical, chemical and biological and are operative in the water column, the humus and soil column beneath the growing plants, and at the interface between the water and soil columns. Because most of the biological transformations take place on or near a surface to which bacteria are attached, the presence of vegetation and humus is very important. Wetland systems are designed to provide maximum production of humus material through profuse plant growth and organic matter decomposition.
Much of the area both north and east of the landfill could be converted to a constructed wetland by constructing a peripheral berm to contain the secondary effluent and divert existing sources of surface runoff. This area is naturally wet and upgradient of Goose Creek which is the most obvious location for ultimate disposal of the effluent. However, a large portion of this land is within the designated buffer zone, which may make it unavailable for treatment purposes.
Sand Filtration Sand filtration is typically utilized to remove TSS and associated BOD levels to less than 10 mg/L. Although a number of different configurations exist, the most common is a moving bed or continuous clean sand filter. This system is typically enclosed within a small building.
Continuous clean filters provide a continuous supply of filtered water without the interruption of backwash cleaning cycles. In the upflow mode, influent enters the bottom of the filter and flows upward through the sand bed. Clean filtrate exits the sand bed and overflows a weir as it leaves the filter. Simultaneously, the sand bed, with the accumulated solids, is drawn downward into the suction of an airlift pipe positioned at the centre of the filter. A small volume of compressed air is introduced into the bottom of the airlift causing a turbulent upward flow of sand, dirt, air, and water.
CBCL Limited Consulting Engineers Treatment Requirements 16 This turbulence scours impurities from the sand. At the top of the airlift dirty slurry spills over into a central reject compartment. Sand returns to the bed through a gravity washer/separator and reject water is returned to the main treatment process.
Peat Filter A peat filter is a biological filtration unit that utilizes naturally occurring microorganisms attached to peat filtration media to biodegrade the contaminants present in the secondary effluent. These systems are typically constructed with earthen berms, clay or synthetic liner, influent distribution system, 600-750 mm layer of peat, and gravel underdrain system.
Wastewater must move through the peat under unsaturated conditions. With a pressure distribution system, wastewater is applied evenly over the peat surface, allowing rapid infiltration. A system of gravel and perforated piping collects the effluent for ultimate disposal. The bottom of the filter slopes slightly to keep effluent from ponding.
Peat filters require more maintenance than conventional tertiary filtration systems. Maintenance includes inspecting all components and cleaning and repairing when needed. Because of the high organic content of peat, the filter media must be periodically replaced. This means physically removing the layer of peat when it has begun to decompose. Life expectancy of the peat media in a filter is estimated to be ten to fifteen years. The system is therefore designed to make it easy to remove and replace the peat. Table 3.6 provides a general comparison of the tertiary treatment options.
Table 3.6 Comparison of Secondary Treatment Options Criteria Constructed Sand Filter Peat Filter Wetlands Polishing Excellent for Removes TSS Excellent for BOD, Characteristics BOD, TSS, and particulate TSS, Nitrogen, and Nitrogen, and BOD only metals metals Capital Cost Low High High Area Requirements 0.5 ha 10 m2 0.3 ha Operating Cost Low Medium High Process Reliability Excellent Good Good Operating Low High Medium Complexity
Due to the land availability, lower cost and complexity issues, the constructed wetland option is preferred for this application.
CBCL Limited Consulting Engineers Treatment Requirements 17 3.2.3 Effluent Discharge The selection of effluent disposal method can be impacted by a number of factors including: Effluent Quality Distance to nearest suitable receiving stream, Potential impacts of point source discharge to receiving stream, Land availability/suitability for alternate disposal options, Potential impacts of cut and cover pipe installation in ecologically sensitive areas or designated buffer zones, Favourable/unfavourable site conditions for pipeline construction.
Effluent discharge options for this application include: Outfall to Goose Creek or alternate receiving stream, Irrigation of treated wastewater on the site, Surface/Subsurface Disposal to existing wet areas on the site.
As with the treatment process selection, the selection of discharge method will be impacted by the selection of the treatment plant site, type of treatment selected, and other restrictions that may be placed on the project. While all options will result in the treated effluent being discharged to the receiving stream, two of the options will further treat the effluent prior to final disposal. Therefore, some further description of each effluent disposal option is provided below.
Outfall (Piped Discharge) This option will require the construction of an outfall from the outlet of the wetland to Goose Creek. This line would have to be constructed through the designated setback area, which is wet and not conducive to civil construction of this type. The outfall would terminate below low water level and may require a multi-port diffuser to better disperse the effluent within the receiving stream.
This option will not provide any additional treatment and will require significant capital expenditure for installation. However, this option will not have any impact on the land between the treatment plant and the receiving stream, with the exception of disturbances caused during construction.
Irrigation of Treated Effluent Wastewater irrigation systems typically include those systems where wastewater is applied to the ground surface at a rate of 50 –100 mm per week and a crop is grown. Methods of application include sprinkler systems, ridge and furrow, and surface flooding. Treated effluent is applied at appropriate intervals after which it percolates through the soil
CBCL Limited Consulting Engineers Treatment Requirements 18 resulting in biodegradation of organic material. It is desirable to have application periods followed by rest periods in the ration of 1:4 or better.
Most spray irrigation systems use a cover crop of grass or other vegetation to maintain porosity in then upper soil layers. In some cases wastes have been sprayed in wooded areas with small trees providing the cover crop. Well drained soils are the most suitable for irrigation system, however, soils types from clays to sands are acceptable. A minimum depth to groundwater of 1200 mm is preferred to prevent saturation of the root zone.
The principle factors governing the capacity of a site to adsorb wastewater are: • Permeability of the soil • Depth to groundwater • Initial moisture content • Terrain and groundcover
In some cases an underdrain system has been installed to improve the drainage conditions of the site such that irrigation can take place. In addition to the irrigation field, other components of the wastewater treatment system for this option include, irrigation water storage, and wastewater application system. These systems are described in the following sections for both the existing facility and the future integrated facility including the proposed expansion.
The irrigation disposal system will require storage during periods when wet weather or frozen ground conditions will not allow land application. Land requirements have been determined based upon the following criteria.
Table 3.7 Irrigation Area Requirements Parameter Value Irrigation Period 6 months Days lost due to wet weather 50 % Potential Irrigation Days 90 days Hydraulic Loading 12 mm/d 50 mm/week BOD Loading 110 kg/ha/d Nitrogen Loading 275 kg/ha/year
Of the criteria listed above, the hydraulic loading criteria is the most stringent. This is primarily because most of the contaminants have been removed prior to irrigation. The land requirements are therefore
CBCL Limited Consulting Engineers Treatment Requirements 19 approximately 3.5 hectares. There are many methods for applying wastewater to the land. The choice of application method generally depends upon factors such as topography, energy requirements, and manpower availability. Some of the more popular methods include sprinkler systems, wheel roll systems, centre pivots, and high volume guns.
While irrigation appears to be a viable option based on land area requirements, the drainage conditions present preclude its use as the wastewater will not consistently percolate through the soil. If implemented, the irrigation system would serve as an effluent distribution system for the overland flow disposal method described below.
Overland Flow Overland flow is both a disposal and treatment process in which wastewater is treated as it flows over slopes covered by vegetation. This method is well suited to soils which are slowly permeable or have an impermeable layer just below the surface. Wastewater is applied to the top of the slope and treatment occurs during the slow travel of water in thin sheet flow down the slope.
Implementation of this effluent disposal option would require the construction of a dispersal zone where the effluent discharges from the wetland. The effluent would then follow the natural slope of the land from the wetland discharge to the salt marsh adjacent Goose Creek. This option seems well suited to the naturally occurring soil conditions and topography on the site. A comparison of the three effluent disposal options is provided below.
Table 3.8 Comparison of Effluent Disposal Options Criteria Outfall Irrigation Overland Flow Treatment No Treatment Removes TSS Excellent for BOD, Characteristics and particulate TSS, Nitrogen, BOD only metals, and organic Capital Cost High Low Very low Area Requirements zero 3.5 ha Function of distance to receiving stream Operating Cost Low Medium Very low
Therefore due to the low cost and compatibility with existing soil properties and topography, the overland flow option is preferred for this application.
CBCL Limited Consulting Engineers Treatment Requirements 20 Chapter 4 Preliminary Design Description
4.1 Site Conditions The process selected will require significant area to construct. An area slightly southwest of the landfill site has been identified as a potential site for construction of the required facilities. Therefore, site conditions were investigated to identify any restrictions that could adversely affect project performance and cost. A complete geotechnical report is included as Appendix A. A summary of the results is included below. The site condition assessment fieldwork was performed on 27 October 2004. Four test pits were dug in the area of the proposed new treatment facilities.
The soil conditions encountered in the test pits consisted of 0.4 m of topsoil/rootmap overlying a compact glacial till of unknown thickness. Bedrock was not encountered within the 3.4 m depth excavated. No evidence of groundwater inflow was observed in three of the four test pit locations, indicating that the groundwater table was below the depth excavated during the investigation. The groundwater table was encountered 1.5 m below the surface at one test pit, and indications that it could rise to within 0.6 m were apparent. Preliminary design of permanent facilities has therefore been focused in the area of the three test pits without groundwater.
In order to maintain separation from the groundwater table, excavation of existing till will be limited. What material is excavated will be suitable for berm construction, however the remainder of the fill, as well as the clay liner will have to be imported. Slopes of no steeper than 3/1 horizontal to vertical are anticipated, with provision of erosion protection to prevent localized sloping of exterior slope.
The soil types prevalent within the overland flow effluent disposal area are from the Mossy Point soil unit. This unit is characterized as very poorly drained with the water table at or near the surface for much of the year. This soil type is wet and unsuitable for agriculture, forestry, or any type of development. At the termination of the effluent disposal area any effluent that has not been assimilated will flow into the Salt Marsh adjacent Goose Creek. The overland flow effluent disposal system will not require any construction within the disposal area. Therefore, geotechnical properties of these soils are not required for the design of the system.
4.2 Collection System Existing leachate produced in Cells 1-3 is pumped from each individual cell to an existing 90 m3 storage tank. A new leachate pump station is
CBCL Limited Consulting Engineers Preliminary Design Description 21 required adjacent to the storage tank to transfer the leachate from Cells 1-3 to the new treatment plant. This pump station is sized to pump leachate at a rate equivalent to the total capacity of the existing and future transfer pumps or approximately 1,520 L/min. A new 150 mm diameter forcemain requires construction along the north and west boundaries of the landfill to transfer the leachate to the new treatment facility. The new leachate pump station and treatment facility are shown in Figure 4.1.
4.3 Treatment System The preliminary design of the treatment facility includes the following components: • Aerated Lagoon • Settling Pond • Constructed Wetland • Overland Flow Effluent Disposal System
The treatment plant includes a complete mix aerated lagoon, settling pond, constructed wetland, and effluent disposal area. Anticipated design parameters are provided in Table 4.1. The location of this plant on the landfill site is shown in Figure 4.1. System configuration is presented in Figure 4.2 with additional details provided in Figures 4.3 and 4.4.
Table 4.1 Design Parameters Parameter Units Value Design Flows Average Yearly m3/d 110 Peak Month m3/d 330 BOD mg/L 200 TSS mg/L 150 TKN mg/L 175 Total-P mg/L 2.1
Leachate collected will be pumped into an initial 6,800 m3 aerated lagoon. The aerated lagoon is designed as a completely mixed cell, which should prevent solids accumulation. Air is supplied by an 11.2 kW positive- displacement blower to four floating laterals, each supplied with 12 fine bubble diffusers. The air will provide both oxygen for conversion of BOD and ammonia as well as mixing energy to keep the pond contents in suspension.
Effluent from the aerated cell will flow by gravity to the settling pond where biological solids, metal hydroxides, and other insoluble components will be removed from the waste stream. Additional biological activity will occur in this pond, which will further reduce BOD, and nitrogen compounds. Biomass and metal hydroxide sludge will accumulate in the
CBCL Limited Consulting Engineers Preliminary Design Description 22 PDF created with pdfFactory trial version www.pdffactory.com PDF created with pdfFactory trial version www.pdffactory.com PDF created with pdfFactory trial version www.pdffactory.com PDF created with pdfFactory trial version www.pdffactory.com settling pond at a rate of approximately 3 tonnes per year. Assuming the sludge will consolidate in the pond to 8 –10% solids, approximately 1% of the pond volume will be utilized for sludge storage on a yearly basis. Therefore, in approximately 20 years after the treatment plant is placed in service, desludging may be required if performance decreases. The sludge will have a relatively high metals content and will therefore need to be disposed of within the landfill as it will not be suitable for land spreading.
Following the settling pond, the wastewater will flow through a constructed wetland for polishing. Upon release from the wetland the leachate will be treated to a tertiary level. However, as overland flow is being utilized as the transport method to convey the effluent to the receiving stream, additional treatment will be realized. The physical characteristics for the entire treatment system are presented in Table 4.2.
Table 4.2 Treatment System Configuration Component Description Aerated Lagoon Volume 6,600 m3 HRT (Average flow) 60 d Oxygen Supply 150 kg/d Air Supply 250 scfm Blower Supply 2 @ 11.2 kW (1 duty, 1 standby) Typical Organic Loading Rate 50 – 200 kg/ha/d Actual Organic Loading Rate 100 kg/ha/d Settling Pond Volume 3,410 m3 HRT (Average flow) 31 d Typical Organic Loading Rate 22 - 67 kg/ha/d Actual Organic Loading Tate 25 kg/ha/d Constructed Wetland Area 2 ha HRT (Average flow) 120 d Typical Organic Loading Rate 100 kg/ha/d Actual Organic Loading Rate 2.2 kg/ha/d Typical Nitrogen Loading Rate 5 –10 kg/ha/d Actual Nitrogen Loading rate 2.5 kg/ha/d Overland Flow Effluent Disposal Slope Width 100 m Slope Length 1000 m Typical Hydraulic Loading Rate 3 – 20 m/yr Actual Hydraulic Loading Rate 0.4 m/yr
CBCL Limited Consulting Engineers Preliminary Design Description 23 4.4 Treatment System Performance The performance of the proposed system has been evaluated based on kinetic models and empirical information from other facilities. While it is intended that compliance limits will be established for the constructed wetland effluent, evaluation of the system should recognize the additional treatment that will occur through the effluent disposal zone. The proposed effluent discharge method is to laterally disperse the effluent across the contour of the land at the effluent end of the wetland. The effluent would then be required to travel over land more than 1,000 m prior to reaching Goose Creek.
Removal efficiencies for the various treatment system components are provided in Table 4.3. Many of the parameters for which an efficiency is stated are composed of many different substances for which removal efficiencies can vary significantly. Therefore, in these cases (i.e. heavy metals, organic priority pollutants) the stated efficiencies have been selected by stating an efficiency at the low end of the spectrum when reviewing typical removals of a wide range of substances for the various treatment types. A further description of the treatment mechanisms to achieve these removals are provided in the following sections.
Table 4.3 Treatment System Performance Parameter Treatment Efficiency Aerated Constructed Overland Overall Lagoon & Wetland Flow Effluent System Settling Pond Disposal Performance BOD 80% Removal 70% Removal 90% Removal 99.4% Removal TSS 80% Removal 90% Removal 90% Removal 99.8% Removal TKN 75% Removal 50% Removal 90% Removal 98.95% Removal Heavy Metals 80% Removal 95% Removal 95% Removal 99.95% Removal Organic Priority Pollutants 95% Removal 95% Removal 98% Removal 99.995% Removal Pathogens 2 log removal 2 log removal 1 log Removal 5 log Removal
4.4.1 Biodegradable Organics and Nutrients Biodegradable organic contaminants, in either dissolved or suspended forms are characterized by the biochemical oxygen demand (BOD) of the waste. Nutrients of importance include nitrogen and phosphorus. While BOD is typically the controlling parameter in lagoon design, nitrogen is the control parameter for many land treatment systems. BOD and nitrogen can be removed biologically through the conversion of BOD to bacterial growth and energy and the conversion of ammonia to nitrate that can then be converted to nitrogen gas through the process of denitrification. Phosphorus removal is typically not as much of a concern as phosphorus deficiency when treating leachate due to low BOD/P ratios. Total
CBCL Limited Consulting Engineers Preliminary Design Description 24 suspended solids are another indicator of organic content. Suspended solids removal is accomplished primarily through sedimentation either directly or preceded by bioflocculation.
4.4.2 Heavy Metals Metals concentration in landfill leachate is typically elevated to sufficient concentrations that metals removal is required prior to effluent release to receiving waters. A large percentage of the metals present in the leachate will accumulate in the sludge produced the biological treatment occurring in the lagoons. Further removals are achieved in the wetland and overland flow systems. Excellent metals removal is achieved in wetlands through precipitation and adsorptive interactions with the organic benthal layer. Less than one percent of the metals removed in wetlands is through wetland plant uptake. Removal of metals in overland flow treatment systems can include uptake by vegetation and adsorption, ion exchange, precipitation, and complexation in or on the soil. The near surface layer in overland treatment systems is very effective for removal, and most retained metals are found in this zone which minimizes the risk of groundwater contamination from this practice.
4.4.3 Organic Priority Pollutants Many organic priority pollutants are resistant to biological decomposition. Therefore volatilization, adsorption, and then biodegradation are the principle methods for removing trace organics in natural treatment systems. Volatilization will occur at the water surface of lagoons and wetlands, as well as the liquid film surface of overland flow systems. Adsorption occurs primarily on the organic matter in the treatment system which is in contact with the waste. In many cases, microbial activity then degrades the adsorbed materials.
4.4.4 Pathogens Pathogenic organisms provide potential risks for groundwater contamination. Treatment lagoons, wetlands, and land treatment systems have been proven to provide very effective control of pathogens. The removal of pathogens in treatment lagoons is due to natural die-off, predation, sedimentation, and adsorption. As the leachate contains significantly less coliforms than typical wastewater, the excellent removal characteristics within the lagoons and wetland will effectively disinfect the effluent prior to discharge into the overland flow disposal system eliminating the risk of groundwater contamination.
4.4.5 Effluent Characteristics Effluent characteristics at various points in the treatment process are provided in Table 4.4. Wetland effluent characteristics can be compared against potential regulatory limits, while overland flow effluent will be
CBCL Limited Consulting Engineers Preliminary Design Description 25 important for the evaluation of potential impacts to the receiving stream. The CCME freshwater guideline has been included in the table for comparison purposes.
Table 4.4 Effluent Characteristics Parameter Unit Raw Setting Pond Wetland Overland Flow CCME Leachate Discharge Discharge to Goose Creek Freshwater Guideline Metals Aluminum µg/L 210 42.0 12.6 2.5 5 - 100 Antimony µg/L 4.6 1.0 0.3 0.1 nr1 Arsenic µg/L 12.8 2.6 0.8 0.2 5 Barium µg/L 288 58.0 17.4 3.5 nr Beryllium µg/L 0.3 0.1 0.02 0.003 nr Bismuth µg/L 9.0 1.8 0.5 0.1 nr Boron µg/L 3234 648.0 194.4 38.9 nr Cadmium µg/L 0.6 0.1 0.03 0.01 0.017 Total Chromium µg/L 43.7 8.8 2.6 0.5 nr Cobalt µg/L 3.6 0.8 0.2 0.05 nr Copper µg/L 10.0 2.0 0.6 0.1 2 - 4 Iron µg/L 11136 2230 670 130 300 Lead µg/L 3.8 0.8 0.2 0.05 1- 7 Lithium µg/L 21.5 4.4 1.3 0.3 nr Magnesium µg/L 75.2 15.0 4.5 0.9 nr Manganese µg/L 9856 1972.0 591.6 118.3 nr Mercury µg/L 0.1 0.02 0.005 0.001 0.1 Molybdenum µg/L 4.5 0.9 0.3 0.05 73 Nickel µg/L 37 8.0 2.4 0.5 25 - 150 Selenium µg/L 13 2.6 0.8 0.2 1 Silver µg/L 0.1 0.02 0.006 0.001 0.1 Thallium µg/L 1.6 0.3 0.1 0.02 0.8 Tin µg/L 1.2 0.2 0.1 0.01 nr Vanadium µg/L 27 6.0 1.8 0.4 nr Zinc µg/L 134 28.0 8.4 1.7 30 Organics Benzene µg/L 1.5 0.08 0.004 0.0004 370 Toluene µg/L 25 1.26 0.06 0.006 2 Ethyl Benzene µg/L 15 0.76 0.04 0.004 90 Total Phenols mg/L 0.3 0.01 0.001 0.0001 0.004 Miscellaneous BOD mg/L 190 38 <10 <5 nr COD mg/L 780 250 150 100 nr TSS mg/L 60 25 10 5 5 mg/L inc. Total Ammonia mg/L 145 26 5 0.2 0.0192 TKN mg/L 170 43 21 2.1 nr Phosphorus mg/L 2.1 1.0 0.20 0.10 nr pH mg/L 7.3 7.8 7.6 7.5 6.5 - 9.0 Fecal Coliforms mg/L 3000 30 <1 <1 143 1. not regulated 2. Free ammonia limit, equivalent to 65 mg/L total ammonia at a pH of 7.5 3. Shellfish water quality limit
CBCL Limited Consulting Engineers Preliminary Design Description 26 Chapter 5 Intermediate Receiving Water Study
5.1 Background The construction of a new leachate treatment facility will require treated effluent to be discharged to a local surface water course. A site plan depicting the landfill site, proposed leachate treatment site, and surrounding area is provided in Figure 5.1. Surface waters require evaluation as potential discharge locations including the Grand River and its tributary, Goose Creek.
Grand River
Goose Creek
Proposed Leachate Treatment Site Landfill Site
Wellington Corner Figure 5.1 Site Plan
The downstream portion of the Grand River system is a tidal estuary that is approximately 500 m wide and relatively shallow with a depth of 1 m. Shellfish harvesting is one of the primary uses of the estuary. The watershed of the Grand River is heavily farmed, which impacts the water quality of the river. Current shellfish closure areas are depicted in Figure 5.2. The proposed leachate treatment plant would discharge effluent into the salt marsh adjacent to a tributary to the Grand River, called Goose Creek. The present study assesses the potential impacts of the new discharge and potential alternatives in the discharge location.
On May 18, 2004, water samples were collected from the Grand River and analysed to determine estuarine quality. The sites were sampled at regular time intervals to reflect water quality during a full tide cycle. The results
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 27 of the sampling data were used to implement a far-field hydrodynamic and water quality model of the river. The water model was calibrated to existing conditions and was then used to simulate the impacts of discharging effluent in various points in Goose Creek. Modelled currents and salinity conditions were input into an initial mixing zone analysis.
Figure 5.2 Current Shellfish Closure Area
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 28 5.2 Preliminary Flow Assessment Flow regime in the Grand River estuary is primarily driven by the local semi-diurnal tides. Tidal elevations in Malpeque Bay vary from about 0.2 to 1 m Chart Datum (CD) for a mean tide (0.8 m tidal range), and 0.2 to 1.3 m CD for a large tide (1.1 m tidal range).
Bathymetric information was obtained from Canadian Hydrographic Service Chart # 4491. The surface area of the estuary upstream of Ellis River Bridge was estimated at 810,000 m2. Based on the required volume of water to fill the tidal prism in the estuary upstream of the bridge, tidal discharge can be roughly estimated between 20 and 30 m3/s. The corresponding maximum tidal flows in Grand River upstream of the bridge are estimated to range from 10 to 30 cm/s. The underlying assumption is that the dimensions of the bridge gap (~100 m wide and 0.5 m deep CD) do not restrict the passage of the tide, which was verified by preliminary hydraulic calculations.
Likewise, maximum tidal flows in the Goose River branch, the most likely discharge location, are estimated to be weaker, from 2 to 5 cm/s.
There is no flow monitoring station at Grand River. A review of the local gauging stations shows that the Smelt Creek (near Ellerslie), North Brook and Wilmot River watersheds are potential candidates for flow estimation by prorating flows with watershed areas. Local soil maps and aerial photographs show that the Grand River watershed is imperfectly drained, with a mix of agricultural and forest areas and slopes of 0 to 2%. Based on these characteristics, the Smelt Creek watershed is most representative for flow estimation. However the station at Smelt Creek was not operating in May 2004 when the sampling was conducted.
The only nearby operating station at the time of sampling with representative enough watershed characteristics was on the Wilmot River. Time-series of flows for Grand River at Days Corner Bridge and for its tributaries were then constructed by prorating the Wilmot River flows with watershed area ratios.
Extreme low flows were estimated based on the representative watershed at Smelt Creek near Ellerslie, where statistics on occurrences of low flows at Smelt Creek are available from Environment Canada. The extreme low summer flow selected and used for the evaluation, is the average low flow that occurs during seven consecutive days, on average once every 20 years
(abbreviated as the 7Q20). The estimated mean flow during the period 11 to 31 May 2004 and the extreme low flow for Grand River and its tributaries are presented in Table 5.1.
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 29 Table 5.1 Low Flow Analysis Surface Area Estimated Mean Extreme Low Flow 2 (km ) Flow 7Q20 (Prorated based on (Prorated based on Wilmot River Flow) Smelt River Flow) Wilmot River 45.4 0.80 Not Applicable Grand River at 40.45 Days Corner Bridge 0.71 0.02 Smelt River 8.7 0.15 0.005 Goose Creek Inflow 3.53 0.06 0.002 Little Trout River 31.6 0.55 0.016
5.3 Background Water Quality Assessment Background water quality data was collected as part of the field program for this study. Sampling sites are shown on Figure 5.3.
Figure 5.3 Sampling sites in Grand River – May 18, 2004
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 30 The concentrations of the various parameters studied were measured at seven sites in the estuary on May 18 2004. Water samples were taken at a water depth of between 0.5 and 1 m below surface. Each site was sampled three to four times at different times of the day corresponding to different stages of the tide. The observations were then used both as input and calibration parameters for the model. The water quality sampling results for Grand River, taken on May 18, 2004, are presented in Tables 5.2 and 5.3.
Table 5.2 Water Quality Sampling Results - General Water Temp Salinity BOD NH -N TSS O-PO DO FC Site 5 3 4 ºC ppt mg/L mg/L mg/L mg/L mg/L MPN/100 mL Min 12.7 14.04 < 1 0.2 9.9 0.21 10 1 1 Max 14.6 22.23 1 0.28 17 0.39 12.4 7 (4 Samples) Avg 13.9 17.84 1 0.24 12.5 0.31 11.6 3 Min 12.6 18.72 < 1 0.2 13.2 0.15 9.3 0 2 Max 14.1 25.74 1 0.32 25.4 0.26 12.2 2 (4 Samples) Avg 13.6 23.4 1 0.25 20.0 0.21 11.4 2 Min 12.3 22.23 < 1 0.16 15.2 0.14 10.6 0 3 Max 14.4 24.57 1 0.24 22.2 0.27 12 13 (4 Samples) Avg 13.6 23.99 1 0.21 17.9 0.2 11.2 5 Min 12.3 22.23 < 1 0.16 18 0.15 8.7 0 4 Max 14.4 24.57 1 0.46 20.4 0.22 12 20 (3 Samples) Avg 13.6 23.4 1 0.29 19.6 0.19 10.7 8 Min 12.2 24.57 < 1 0.12 15.3 0.1 9 0 5 Max 13.9 26.91 1 0.46 65.8 0.22 12.2 2 (4 Samples) Avg 13.3 25.45 1 0.235 37.9 0.16 11.0 1 Min 11.5 29.25 < 1 0.12 18.5 0.06 12.1 0 6 Max 11.8 29.25 < 1 0.55 26 0.1 12.4 0 (3 Samples) Avg 11.7 29.25 < 1 0.28 21.8 0.077 12.2 0 Min 11.1 29.3 1 0.16 24.8 0.06 11.40 0 7 Max 11.1 29.3 1 0.16 24.8 0.06 11.40 0 (1 Sample) Avg 11.1 29.3 1 0.16 24.8 0.06 11.40 0
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 31
Table 5.3 Water Quality Sampling Results - Metals Metals Site As Cd Cu Fe Pb Ni Se Zn µg/L µg/L µg/L µg/L µg/L µg/L µg/L µg/L Min < 5 0.3 43 366 < 2 13 < 5 < 5 3 Max 7 1.1 57 428 2 18 5 < 5 (4 Samples) Avg 6 0.7 50 397 2 15.5 5 < 5 Min < 5 0.2 27 285 < 2 13 < 5 < 5 4 Max < 5 0.3 40 319 < 2 37 5 < 5 (3 Samples) Avg < 5 0.25 33.5 302 < 2 25 5 < 5 Min < 5 0.4 36 480 < 2 6 < 5 5 5 Max 22 0.5 49 2073 2 65 5 23 (4 Samples) Avg 13.5 0.5 41 1416 2 32 5 11 Min 10 0.9 40 285 2 20 < 5 < 5 6 Max 15 1.6 41 443 3 43 6 < 5 (3 Samples) Avg 12.5 1.3 40.5 364 2.5 31.5 5.5 < 5
The following water quality observations were made on the day of sampling.
Dissolved Oxygen Within the temperature and salinity conditions, dissolved oxygen (DO) saturation concentrations are between 9 and 10 mg/L. Measured DO values were around 11 mg/L (i.e., showed supersaturated conditions). This could be caused by the following factors:
• Surface water reaeration from high winds Hourly speed on May 18 ranged from 20 to 40 km/h (from Charlottetown weather station data). There were 1.5 to 2 ft waves and white caps throughout the day.
• A phytoplankton bloom (also called algal bloom) A bloom usually occurs near the surface where light is available. Given the right temperature and salinity conditions, high levels of nutrients (nitrogen and phosphorus, from local agricultural activities) can cause a bloom. DO levels will then increase, as phytoplankton produce oxygen as part of the photosynthetic process during the day. At night, DO levels decrease sharply as the algae consume the oxygen. When the nutrients are depleted, algae populations drop sharply. During this ‘crash’, the dead algae sink to the bottom where decomposed organisms use oxygen to break them down. DO levels will therefore decrease during this time period. However, note that the measured water temperature was too low for optimal bloom conditions.
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 32
Five-Day Biochemical Oxygen Demand (BOD5)
BOD5 levels were measured as less than 2 mg/L (the detection level), and model results showed levels around 1 mg/L or lower throughout the estuary, with no discernible spatial distribution pattern.
Nutrients Sampling results show ammonia concentrations ranging from 0.12 to 0.55 mg/L and phosphorus concentrations from 0.06 to 0.39 mg/L. This points to high nutrient concentrations on the upper reaches of the estuary where dilution of runoff from agricultural areas is reduced.
Fecal Coliform Coliform bacteria was detected upstream of Ellis River Bridge in varying levels, from 0 up to 20 MPN/100 mL, the value of 20 having been measured in Goose Creek. These observations are generally lower than the CCME guideline limit for shellfish harvesting of 14 counts/100 mL.
Total Suspended Solids Measured concentrations of total suspended solids were around 12.5 mg/L at the upstream-most site (Site 1). Higher values were observed at Site 5 (mean value of 38 mg/L), just upstream of Ellis River Bridge, where tidal currents are likely to be the strongest due to the bridge constriction. Measured values throughout the estuary are higher than those for typical seawater (5 to 10 mg/L), which is likely due to tidal mixing and sediment re-suspension processes.
Metals A total of 14 samples at 4 sites were analysed for total metals. Measured concentrations are generally higher than recommended limits for aquatic life, however this may be due to the metals contained in the sediment. As an example, arsenic levels show spatial variability and were higher than the 12.5 µg/L limit recommended for marine life (Table 5.4) at Sites 5 and 6. Measured cadmium values (0.2 to 1.6 µg/L) were also found consistently higher that the recommended 0.12 µg/L limit for marine life.
5.4 Dilution Assessment Water quality is impacted by both dilution and biological and physical modifications within the estuary. Anticipated effluent quality is tabulated in Table 4.4. The results of the initial dilution assessment are provided in the following sections. The dilution assessment was performed with a single port discharge, however, the actual discharge will be distributed along a length of salt marsh adjacent the upper reaches of Goose Creek. As the length of the distributed effluent source is difficult to estimate and
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 33 point source discharge is a more conservative approach in estimating the effect of dilution, the point source was utilized in the dilution analysis.
5.4.1 Near-Field Near-field dilution (i.e. within 50 m from the outfall) in the Goose Creek area will be limited by the following factors:
• Shallow water depths, from about 1 foot CD at the head to 2 feet at the mouth of Goose Creek (from CHS chart #4491). This limits available dilution during the initial turbulent rise of the buoyant plume.
• Relatively weak tidal currents, which limits initial longitudinal dispersion once the plume has risen to the surface. Hydrodynamic model results from Section 5.4.2 show that average tidal currents range from 1cm/s at the head of Goose Creek to 5 cm/s in Grand River channel immediately upstream of confluence with Goose Creek.
• Limited channel width, from about 50 to 150 m at low tide. This limits the potential lateral dispersion due to turbulent diffusion and surface wind stress, once the plume has risen to the surface.
To estimate the extent of the above limitations, an initial mixing zone analysis was conducted using the U.S. EPA’s UM3 model from the Visual Plumes modelling package. UM3 (“Updated Merge”) simulates the initial rise of a submerged buoyant plume from a single or multi-port discharge, based on ambient current and hydrographic conditions. Once the plume has reached the surface, the model uses a far-field algorithm to compute dispersion away from the initial mixing zone, based on plume travel time and initial waste-field width when the plume hits the surface.
A range of representative cases were modelled, consisting of a single 4” diameter port, located at the bottom in a depth of 0.8 to 1.1 m, oriented perpendicular to the ambient current, and with an effluent flow of 0.095 m3/s (Peak Daily Flow). Typical tidal current and salinity conditions were output from hydrodynamic model results described in Section 5.4.2.
The near-field assessment examines available dilution ratios, which does not account for background effluent concentrations. The likelihood for pollutant build-up due to reversing tides is addressed in the far-field analysis presented in Section 5.4.2. Results are presented in Table 5.4. These results show that initial mixing zone will provide dilution of approximately 15:1. Based on the effluent concentrations presented in Table 4.4 being reduced by a further 15:1, marine water quality does not appear to be an issue, even within the near field.
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 34 Table 5.4 Near-field Dilution Modelling Results Parameter Upper Goose Creek Mid-tide depth, m 0.8 Typical current, m/s 0.01 Salinity, PSU 23 Initial mixing zone Distance away from source 3.5 when plume surfaces (m) Initial average dilution 15.1 when plume surfaces Average dilution 10 m away from outfall 23.5 after the plume hits 50 m away from outfall 56.0 the surface Plume width after 10 m away from outfall 3.2 the plume hits the 50 m away from outfall 7.8 surface
Effluent dispersion in the far-field will then depend on variations in depth and hydrodynamic conditions. An assessment of far-field effluent dispersion based on hydrodynamic modelling is presented in the following section, which also examines residence time and the potential for effluent build-up.
5.4.2 Far-Field Flow and Water Quality Modelling The model utilized was CE-QUAL-W2 Ver. 3.2, a two-dimensional, laterally averaged, hydrodynamic and water quality model, developed by the US Army Corps of Engineers. The water quality and hydrodynamics are averaged in the lateral direction. The model uses downstream tidal forcing, upstream freshwater inflows and surface meteorological inputs to solve the hydrodynamic momentum and continuity equations in the longitudinal and vertical directions. Hydrodynamic results are used to drive the water quality simulation given input parameter concentrations specified at the boundaries. These can include the release of effluent through a point or distributed source. For each model segment, the model resolves the vertical structure of temperature, salinity and key water quality parameters. Decay rates and interactions between modelled constituents are taken into account. The assumption of complete lateral mixing is valid for long and narrow water bodies, which is the case here in the area of interest.
Detailed model bathymetry was set up from CHS Chart, #4491. The grid features three branches, 12 horizontal layers of 0.5 m and 26 segments of length from about 100 to 500 m. Horizontal model domain layout is shown in the Figure 5.4.
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 35 Little Trout River Inflow
Smelt River Inflow
Goose Creek Nebraska Days corner Creek bridge
Figure 5.4 Horizontal Model Domain Layout
Input parameters included the following: • Flow and water quality parameters for the boundaries (3 branches, 2 tributaries and the downstream boundary) • Initial conditions in the estuary and ocean at every 0.5 m depth, calibrated on the sampling results • Hourly tide elevations for the downstream boundary for 2 weeks centred on the sampling day (May 18 2004), which covers one full spring-neap tidal cycle. This ensures model results account for tidal variability. • Hourly meteorological data (wind, air temperature, dew point, cloud cover) from the Charlottetown weather station, for 2 weeks centred on the sampling day.
A summary of boundary conditions is shown in Table 5.5. Values were based on site-specific averages from sampling results. The model was calibrated by adjusting input parameters in order to get modelled water quality parameters to match sampling data on the sampling day.
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 36 Table 5.5 Input Parameter Values Model Input Ocean Grand Goose Smelt Little Trout Parameter (Malpeque River Creek River River Bay) Boundary Inflow Inflow Infow Inflow FC, cfu/100mL 0 3 7 3 3 DO, mg/L 11.4 12 11 11 11 BOD, mg/L 1 0.8 0.67 1 1 TSS, mg/L 24.8 15 19.6 40 40 SAL, mg/L 29 (surface) to 20 24 20 20 30 (bottom) PO4, mg/L 0.06 0.3 0.2 0.2 0.2
NH3, mg/L 0.16 0.24 0.29 0.29 0.29
Due to lateral averaging, model accuracy may be reduced in the wider, seaward segments of the estuary. In terms of water quality, the influence of algae was not included in the model, due to the lack of field data on algae concentrations needed to support modelling efforts. The present model therefore does not handle eutrophication processes (i.e. a condition in an aquatic ecosystem where high nutrient concentrations stimulate blooms of algae).
Model Results Snapshots of modelled salinity profiles for high and low tide on May 18 are shown in Appendix A (Figure A1). A 10-day-time series of model results is presented for each sampling site in Figures A2 through A9. The plots are centered on the sampling day, i.e. May 18 (Julian day 139).
These results show the strong influence of the semi-diurnal tides on the current regime and to a lesser extent on the water quality parameters. Hydrodynamic results are consistent with estimates based on simple hydrodynamic calculations (cf tidal prism method, Section 5.2). A reasonable match with observations was obtained for key water quality parameters.
Note that the input DO values are purposely supersaturated in order to reproduce existing conditions. It is not known if the observed supersaturated conditions actually persisted for the modelled time period. Likewise, the inflow concentrations of water quality parameters was kept constant throughout the run in order to match observed values on May 18. The accuracy of these results could not be verified for the remainder of the run.
However, the good agreement on background conditions between results and observations for that day allows for an impact assessment of effluent discharge. This assessment is based on the same input concentrations for
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 37 existing inflows and on an additional effluent input flow, as presented in Section 5.4.3.
Residence Time The residence time, also called water age, is an estimate of the maximum time spent by particles of water in a body of water. It can also be called renewal time or time of flushing of the estuary. Residence time was modelled as a state variable that increases by 1 every day, (i.e. with a –1 day-1 zero-order decay rate). The results, presented in Figure 5.5, are an exact representation of the water age within each model segment. Water coming from outside the model boundaries is considered new water, and the analysis does not account for water that could re-enter the system at rising tide. It shows that maximum residence times in the estuary occur upstream of the bridge, where flushing takes about 8 days to complete. Results for the Goose Creek branch were also in the order of 8 days. Higher residence times for surface waters downstream of the bridge characterize fresher water coming from upstream, generally having spent more time in the estuary than denser water brought in by the tide in the deeper layer. Residence time in the Goose Creek area was estimated at about 8 days.
k e e e days r c C n e
e 8.5 e g u s l d f Sampling sites o i 8 r o n o along Grand River 1 2 G 5 B 6 7 7.5 C 7
) 6.5
m
( -1 6
e
c 5.5
a
f r -2 5
u
s 4.5
w 4
o -3 l 3.5 e
b
3
h -4 t 2.5
p
e 23456789101112131415 2
D Model segment, going downstream 1.5 1
Figure 5.5 Water Age Within Each Model Segment
5.4.3 Modeled Impact on Water Quality The model was run for a 28-day period (i.e. two full spring-neap tidal cycles) with effluent released in Goose Creek. Input effluent flow and concentrations were based on the following parameters: • Peak daily flow: 822 m³/day = 0.095 m³/s • BOD concentration = 10 mg/L • TSS concentration = 10 mg/L
• NH3 concentration = 10 mg/L
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 38
The above concentrations are intended to represent worst-case estimates. Most of the time the actual concentrations in the released effluent will be much lower.
The analysis is based on the assumption that complete longitudinal effluent mixing is achieved within a cell. This approximation means that model results are valid only in the far-field zone away from the initial mixing zone. Cell sizes in the upper reaches of the estuary are in the order of 100 x 300 m. Therefore model results are valid starting about 100 m away from the outfall. The effluent was released continuously for 28 days at peak daily flow.
Results in terms of effluent concentration are shown in Figure A10. Each curve represents the modelled far-field effluent concentration averaged over the model grid cell that contains a reference location. First, the results suggest there is likely no potential for pollutant build-up in any of the upper reaches of the estuary. The plots show that effluent build-up stabilizes between 5 to 10 days after initiation of continuous release, which is in line with modelled residence times for the area. Tidal flushing then keeps the concentrations at near-constant levels at all locations. The plots on Figure A10 also show sensitivity to the spring-neap tidal cycle. Concentrations in Goose Creek drop somewhat between day 7 and 15 and after day 22, which corresponds to spring tides (i.e., of higher range) inducing higher tidal currents with increased flushing.
Therefore, based on a worst-case 50:1 initial dilution 100 m away from the outfall (upper Goose Creek release), BOD5, TSS, and NH3 concentrations from the effluent would drop to 0.2 mg/L. Even if the entire BOD load were to be instantly converted, only 2% of the measured background DO (~10 mg/L on May 18) would be consumed. Similarly, measured background TSS values of ~20 mg/L would only rise by 1%. The only non-negligible effect would be on ammonia, where measured values of about 0.2 mg/L could at least double in the release area. Still, 0.4 mg/L of total ammonia is still well below typical guidelines.
Anticipated effluent concentrations of metals (Table 4.4) are lower than guidelines. Therefore the impact on receiving water quality for these parameters will be negligible.
Hydrodynamics in the Grand River estuary are driven by semi-diurnal tides. The analysis shows that tidal flushing provides sufficient far-field dilution to the effluent in order for DO, BOD and ammonia to be within guideline limits in the receiving water body. Anticipated effluent concentrations of metals and TSS are already within or lower than water
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 39 quality criteria and measured background levels. Therefore the impact on receiving water quality for the effluent released from the proposed treatment facility will be negligible.
CBCL Limited Consulting Engineers Intermediate Receiving Water Study 40 Chapter 6 Cost Estimates
6.1 Capital Costs Preliminary capital cost estimates are provided in Table 6.1. The costs include a 25% allowance for contingency and engineering but do not include any applicable taxes.
Table 6.1 Preliminary Capital Estimates Project Component Capital Cost Site Development $30,000 Yard Piping 50,000 Leachate Transfer 200,000 Earthworks 260,000 Building/Process Equipment 200,000 Mechanical/Electrical 75,000 Site Finishing/Fencing 35,000 Total $850,000
6.2 Operation & Maintenance Costs Operations and maintenance costs are provided in Table 6.2. Power is calculated utilizing a rate of $0.10 per kWh. Labour allowance is based on a total of 750 hours at a rate of $25 per hour. This allows for approximately 15 hrs per week on average. Labour requirements will fluctuate seasonally as seasonal site maintenance tasks are undertaken. An allowance for lagoon sludge removal and disposal will result in finds being available for this item when it is required in approximately 10 years following initial start-up.
Table 6.2 Operation and Maintenance Costs Estimates Item Operating Cost ($/yr) Power $16,000 Labour 19,000 Sampling / Analysis 3,000 Lagoon sludge removal/disposal 5,000 Repairs & Maintenance 3,000 Total $46,000
CBCL Limited Consulting Engineers Cost Estimates 41 Appendix A Geotechnical Report from Jacques Whitford
CBCL Limited Consulting Engineers Appendices
Appendix B Supporting Figures for Receiving Water Study
CBCL Limited Consulting Engineers Appendices
k e e e r c
C n e
e e g u s l d Salinity Sampling sites o i nf r o o (ppt) along Grand River 1 2 G 5 B 6 7 C 29.5 29 -1 28.5 21 22 23 25 27 28
) -2 27.5
m 27
(
-3 26.5
ce LOW TIDE
a 26
f r 29 25.5
su 25
w
o 24.5 l -1 e 24
b 23.5 h t -2 23 24 25 p 21 22 26 23
e 22.5
D -3 22 HIGH TIDE 21.5 21 2 3 4 5 6 7 8 9 10 11 12 13 14 15 20.5 Model segment, going downstream 20
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Modelled salinity for May 18, 2004 Figure A1 Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 1
30 30Water surface * 20 2010, m CD Salinity, ppt 10 10
0 0Current, cm/s -10 -10
-20 -20 -30 -30 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 1
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A2 the surface layer at site 1 - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 2
30 30Water surface * 20 2010, m CD Salinity, ppt 10 10
0 0Current, cm/s -10 -10
-20 -20
-30 -30 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 2
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A3 the surface layer at site 2 - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 3
30 30Water surface * 10, m CD 20 20Salinity, ppt
10 10Current, cm/s
0 0
-10 -10 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 3
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A4 the surface layer at site 3 - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 4
30 30Water surface * 10, m CD 20 20Salinity, ppt
10 10Current, cm/s
0 0
-10 -10 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 4
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A5 the surface layer at site 4 - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 5
30 30Water surface * 20 2010, m CD Salinity, ppt 10 10
0 0Current, cm/s -10 -10
-20 -20
-30 -30 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 5
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A6 the surface layer at site 5 - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Bridge
30 30Water surface * 20 2010, m CD Salinity, ppt 10 10
0 0Current, cm/s -10 -10
-20 -20
-30 -30 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Bridge
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A7 the surface layer at the bridge - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 6
30 30Water surface * 20 2010, m CD Salinity, ppt 10 10
0 0Current, cm/s -10 -10
-20 -20
-30 -30 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 6
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A8 the surface layer at site 6 - Based on existing conditions Modelled hydrodynamics and salinity, surface layer - Existing conditions - Site 7
30 30Water surface * 20 2010, m CD Salinity, ppt 10 10
0 0Current, cm/s -10 -10
-20 -20
-30 -30 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer - Existing conditions - Site 7
25 25 BOD5*10, mg/l 20 DO, mg/l20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 10 FC, cfu/100ml 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled hydrodynamics and water quality parameters in Figure A9 the surface layer at site 7 - Based on existing conditions Effluent Release in Upper Goose Creek
2.5 2 1.5 1 0.5
% of initial concentration % initial of 0 0 5 10 15 20 25 Days
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Evolution of modelled far-field effluent concentration in surface layer Figure A10 at selected sampling sites - Based on Peak Daily Flow Modelled water quality parameters, surface layer, site 3 - Effluent release in upper Goose Creek
BOD5*10, mg/l 25 25 DO, mg/l 20 20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 FC, cfu/100ml10 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
Modelled water quality parameters, surface layer, site 4 - Effluent release in upper Goose Creek
BOD5*10, mg/l 25 25 DO, mg/l 20 20 PO4*10, mg/l 15 15 NH3*10, mg/l 10 FC, cfu/100ml10 5 TSS,5 mg/l
0 0 135 136 137 138 139 140 141 142 143 144 145 Julian day of 2004
East Prince Waste Management Facility – Leachate Treatment System – 27 July 2004 Receiving Water Quality Study
Modelled water quality parameters in the surface layer at sites 3 and 4 Figure A11 - Based on effluent release in Upper Goose Creek