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Appendix C. Contaminant Flux Modelling

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Appendix C. Contaminant Flux Modelling West Carleton Environmental Centre 9RPT_T09_2012-01-31_App C_60242342.Docx C-1 Appendix C. Contaminant Flux Modelling The maximum concentration at the base of the liner system was estimated using POLLUTE Version 7.14. The Generic II Double Liner system as specified in Regulation 232/98 was modelled, consisting of the following components (from top down): 1.5 mm thick HDPE geomembrane of the primary composite liner. 0.75 m thick compacted clayey layer of the primary composite liner (maximum k = 10 -7 cm/s). 0.3 m thick granular layer of the secondary leachate collection system. 2 mm thick HDPE geomembrane of the secondary composite liner. 0.75 m thick compacted clayey layer of the secondary composite liner (maximum k = 10 -7 cm/s). 1 m thick natural or constructed soil attenuation layer. The primary leachate collection system considered in the model accounts for the hydraulic head on the primary composite liner and the amount of leachate collected by the system. The overburden-shallow bedrock aquifer on site is assumed to be below the attenuation layer. Details of the leachate concentration input parameters are shown in Table 5-2 in the main report. The liner and leachate collection system was modelled reflecting a progressive failure in accordance with Regulation 232/98 as follows: all liner and leachate collection systems are functioning properly from 0 to 100 years; the primary leachate collection system fails at year 100 and the head on and the leakage through primary composite liner increases; the geomembrane of the primary composite liner system is assumed to fail in year 150 and allows the head on the primary composite liner to dissipate; and the leakage through the secondary composite liner increases when the secondary geomembrane fails in Year 350. A summary of the estimated maximum concentration at the base of the liner system (the base of the attenuation layer) as calculated by the POLLUTE model are shown in Table 5-3 in the main report. Plots of the calculated concentrations at various depths of the liner system and at the aquifer in contact with the attenuation layer at the base of the liner system area are attached. The ten plots included cases for both with and without leachate recirculation for the five selected parameters - ammonia, chloride, potassium, sodium and trichloroethylene (TCE). The results
Transcript
Page 1: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-1

Appendix C. Contaminant Flux Modelling

The maximum concentration at the base of the liner system was estimated using POLLUTE

Version 7.14. The Generic II – Double Liner system as specified in Regulation 232/98 was

modelled, consisting of the following components (from top down):

1.5 mm thick HDPE geomembrane of the primary composite liner.

0.75 m thick compacted clayey layer of the primary composite liner

(maximum k = 10-7 cm/s).

0.3 m thick granular layer of the secondary leachate collection system.

2 mm thick HDPE geomembrane of the secondary composite liner.

0.75 m thick compacted clayey layer of the secondary composite liner

(maximum k = 10-7 cm/s).

1 m thick natural or constructed soil attenuation layer.

The primary leachate collection system considered in the model accounts for the hydraulic head

on the primary composite liner and the amount of leachate collected by the system. The

overburden-shallow bedrock aquifer on site is assumed to be below the attenuation layer.

Details of the leachate concentration input parameters are shown in Table 5-2 in the main

report.

The liner and leachate collection system was modelled reflecting a progressive failure in

accordance with Regulation 232/98 as follows:

all liner and leachate collection systems are functioning properly from 0 to

100 years;

the primary leachate collection system fails at year 100 and the head on and the

leakage through primary composite liner increases;

the geomembrane of the primary composite liner system is assumed to fail in year

150 and allows the head on the primary composite liner to dissipate; and

the leakage through the secondary composite liner increases when the secondary

geomembrane fails in Year 350.

A summary of the estimated maximum concentration at the base of the liner system (the base of

the attenuation layer) as calculated by the POLLUTE model are shown in Table 5-3 in the main

report.

Plots of the calculated concentrations at various depths of the liner system and at the aquifer in

contact with the attenuation layer at the base of the liner system area are attached. The ten

plots included cases for both with and without leachate recirculation for the five selected

parameters - ammonia, chloride, potassium, sodium and trichloroethylene (TCE). The results

Page 2: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-2

show that chloride has the highest ratio of calculated maximum concentration to the assumed

initial concentration in the waste. The results are consistent with chloride being a conservative

parameter without retardation and decay as assumed in the POLLUTE model.

Sensitivity analyses were also performed to examine how different input parameters may affect

the calculated maximum concentration at the base of the liner system in contact in the

overburden-shallow bedrock aquifer. Cases considered and the results are summarised in

Table C-1. The results of the sensitivity analyses illustrated that the calculated maximum

concentration at the base of the liner system is more sensitive to change to some parameters

than others.

Page 3: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-3

Plot 1 – Ammonia (No Leachate Recirculation)

Plot 2 – Ammonia (Leachate Recirculation)

Page 4: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-4

Plot 3 – Chloride (No Leachate Recirculation)

Plot 4 – Chloride (Leachate Recirculation)

Page 5: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-5

Plot 5 – Potassium (No Leachate Recirculation)

Plot 6 – Potassium (Leachate Recirculation)

Page 6: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-6

Plot 7 – Sodium (No Leachate Recirculation)

Plot 8 – Sodium (Leachate Recirculation)

Page 7: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-7

Plot 9 – TCE (No Leachate Recirculation)

Plot 10 – TCE (Leachate Recirculation)

Page 8: Appendix C. Contaminant Flux Modelling

Appendix C. Contaminant Flux Modelling

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App C_60242342.Docx C-8

Table C-1: Inputs and Results of Sensitivity Analysis, POLLUTE Model

Sensitivity

Analysis

Cases

Base Case Parameter Value in Base

Case

Revised Value

for Sensitivity

Analysis

Calculated Maximum

Concentration at the

Base of the Liner

(mg/L)

Calculated Maximum Concentration

at the Base of the Liner for the

Corresponding Base Case with the

Change in the Parameter (mg/L)

Change in

Calculated

Maximum

Concentration

S1

Chloride (No

Leachate

Recirculation)

Initial Concentration 2,911 mg/L

(average)

5,140 mg/L

(peak) 114 123 18%

S2

Chloride (No

Leachate

Recirculation)

Mass of the Parameter as

a Proportion of Total

Waste Mass

2,100 mg/kg 3,150 mg/kg

(50% more) 114 190 67%

S3

Chloride (No

Leachate

Recirculation)

Base Aquifer Thickness 11.4 m 9.98 m (lower

range) 114 126 11%

S4

Chloride (No

Leachate

Recirculation)

Head on Primary

Leachate Collection

System (System

Operational)

0.3 m 0.6 m (100%

more) 114 152 33%

S5

Chloride (No

Leachate

Recirculation)

Maximum Head on

Primary Leachate

Collection System

(System Failed)

8 m 12 m (50%

more) 114 115 1%

S6 Chloride (Leachate

Recirculation)

Leachate Recirculation

Rate 100 mm per year

50 mm per year

(50% less) 165 136 -18%

S7

Ammonia (No

Leachate

Recirculation)

Half Live 20 years 40 years (100%

more) 0.046 0.75 1600%

S8 TCE (No Leachate

Recirculation) Decay In Waste and Liner In Waste Only 3.0E-05 6.6E-05 220%

Note: The revised values of the parameters used do not imply that these are potential variations.

Page 9: Appendix C. Contaminant Flux Modelling

Appendix D Landfill Gas Generation Assessment

Page 10: Appendix C. Contaminant Flux Modelling

Appendix D. Landfill Gas Generation Assessment

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App D_60242342.Docx

Appendix D. Landfill Gas Generation Assessment

The U.S. EPA Landfill Gas Emissions Model (LandGEM), Version 3.02, was used to estimate

gas generation rates for the new landfill. The model is based on a first-order decomposition rate

equation for estimating emissions from the anaerobic decomposition of landfilled waste in

municipal solid waste landfills,. Landfill gas generation rates were estimated based on an

annual waste disposal rate of 400,000 tonnes over 10 years.

Two key input parameters in LandGEM are the Methane Generation Rate (k) and the Potential

Methane Generation Capacity (Lo). LandGEM provides default values of k and Lo of 0.04 year-1

and 100 m3/Mg respectively for Conventional landfills. Default values are also available for Arid

type landfills (e.g., sites located in areas that receive less than 635 mm (25 inches) of rainfall

per year) but are not considered representative for the WM site. The United States Clean Air

Act (CAA) also identifies default k and Lo values of 0.05 year-1 and 170 m3/Mg respectively.

The LandGEM Conventional and CAA default values were both used to model landfill gas

generation rates. The results indicate estimated peak total landfill gas generation rates of

26 million m3/year (1,800 cfm) and 54 million m3/year (3,600 cfm) based on the LandGEM

Conventional and CAA default k and Lo values respectively. The model results also indicate

that the peak generation rates will occur in one to two years after the end of landfilling. The gas

generation rates over time are shown in Figures D-1 and D-2.

Page 11: Appendix C. Contaminant Flux Modelling

Appendix D. Landfill Gas Generation Assessment

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App D_60242342.Docx

Page 12: Appendix C. Contaminant Flux Modelling

Appendix E Truck Traffic Associated with the

Importation of Construction Materials

Page 13: Appendix C. Contaminant Flux Modelling

Appendix E. Truck Traffic Associated with the Importation of Construction Materials

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App E_60242342.Docx E-1

Appendix E Truck Traffic Associated with the Importation of Construction Materials

In addition to the truck traffic generated by hauling waste to the site, traffic will also be

generated through importation of construction materials. The traffic levels associated with

importation activities were estimated as follows:

The approximate quantity of materials to be imported was estimated based on the

conceptual design presented in the FCR. It was assumed that existing on-site

soils could be cut/filled to achieve the overall site grading, but that all material

required for the base liner, lcs, and final cover, as well as fills to supplement base

grading requirements would be imported.

Material quantity to be imported from off-site was converted to number of loads by

assuming a typical truck load would carry a volume corresponding to 10 m3 of

material in-situ. For on-site truck movements a typical truck load was assumed to

correspond to 18 m3 of material in-situ

Traffic levels were calculated (expressed as trips per hour) by making assumptions

regarding the period over which materials would be imported.

The traffic estimates are provided in Table E-1.

Page 14: Appendix C. Contaminant Flux Modelling

Appendix E. Truck Traffic Associated with the Importation of Construction Materials

West Carleton Environmental Centre

9RPT_T09_2012-01-31_App E_60242342.Docx E-2

Table E-1: Estimates of Landfill Construction Material Volumes and Related Traffic

A. LINER/COVER AREAS TOTALS

Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 Stage 6 Stage 7 Stage 8 Stages 1-4 Stages 4-8

Area of Liner Stage sq m 47,250 47,250 47,250 47,250 47,250 47,250 47,250 47,250 378,000

Area of Cover Stage sq m 189,000 189,000 378,000

B. CONSTRUCTION MATERIAL QUANTITIESBase Grading and Site Preparation Earthworks

Base Grading Cut (within limit of landfill) cu m 115,622 47,450 60,089 51,117 20,152 26,467 10,094 8,817 339,808

Base Grading Fill (within limit of landfill) cu m 2,496 12,520 1 1,157 3,714 8,725 8,159 18,264 55,036

Cut/Fill Balance (within limit of landfill) cu m 113,126 34,930 60,088 49,960 16,438 17,742 1,935 (9,447) 284,772

Eng Fill Req'd for Perimeter Berms, Road Base, and SWM Ponds cu m 180,430 131,400 24,150 17,850 29,400 36,750 67,665 82,080 569,725

Overall Engineered Fill Balance cu m (67,304) (96,470) 35,938 32,110 (12,962) (19,008) (65,730) (91,527) (284,953)

Subtotal - Imported Engineered Fill cu m 67,304 96,470 0 0 0 0 29,652 91,527 284,953

Area of granular maintenance road (allow pavement 600 mm thick) sq m 3,735 3,240 1,365 1,615 1,365 1,615 2,990 3,240 19,165

Area of paved haul road (allow pavement 1000 mm thick) sq m 0 28,495 0 2,310 0 2,310 0 3,245 36,360

Subtotal - Imported Granular and Asphalt for Road

Pavementcu m 2,241 30,439 819 3,279 819 3,279 1,794 5,189 47,859

Liner, Leachate Collection System, and Final Cover (Soil and Granular Components)

Attenuation Layer (Clay) - 1.00m cu m 47,250 47,250 47,250 47,250 47,250 47,250 47,250 47,250 378,000

Secondary Liner (Clay) - 0.75m cu m 35,438 35,438 35,438 35,438 35,438 35,438 35,438 35,438 283,500

Secondary Leachate Collection System (Granular) - 0.30m cu m 14,175 14,175 14,175 14,175 14,175 14,175 14,175 14,175 113,400Primary Liner (Clay) - 0.75m min, varies to create washboard

contour cu m 45,500 45,500 45,500 45,500 45,500 45,500 45,500 45,500 364,000

Primary Leachate Collection System (Granular) - 0.30m cu m 14,175 14,175 14,175 14,175 14,175 14,175 14,175 14,175 113,400

Final Cover Barrier Layer Soil - 0.60m cu m 113,400 113,400 226,800

Final Cover Top Soil - 0.15m cu m 28,350 28,350 56,700

Subtotal - Imported Soil and Granular for Liner, LCS,

and Final Covercu m 156,538 156,538 156,538 156,538 156,538 156,538 156,538 156,538 141,750 141,750 1,535,800

Total - Imported Soil and Granular Material cu m 226,083 283,447 157,357 159,817 157,357 159,817 187,984 253,254 141,750 141,750 1,868,612

Liner and Leachate Collection System (Geosynthetics and Piping)

Area of Geomembrane sq m 94,500 94,500 94,500 94,500 94,500 94,500 94,500 94,500 756,000

Area of Geotextile sq m 189,000 189,000 189,000 189,000 189,000 189,000 189,000 189,000 1,512,000

Length of LCS Piping lin m 1,770 1,350 1,770 1,350 1,770 1,350 1,770 1,350 12,480

C. SITE CONSTRUCTION TRAFFIC Total Imported Loads Soils/Granular loads 22,608 28,345 15,736 15,982 15,736 15,982 18,798 25,325 14,175 14,175

Total Imported Loads Geosynthetics/Pipe loads 32 31 32 31 32 31 32 31

Total On-site Loads Soil loads 6,423 2,636 3,338 2,840 1,120 1,470 561 490

Soil/Granular/Geosynthetic/Pipe Importation trips/hr 20.1 25.2 14.0 14.2 14.0 14.2 16.7 22.5 12.6 12.6

On-Site Truck Movements trips/hr 5.7 2.3 3.0 2.5 1.0 1.3 0.5 0.4 0.0 0.0

Notes 1. Imported soil/granular loads equivalent to 10 m3 in-situ/load, and on-site loads equivalent to 18 m3 in-situ/load.2. Area of 3. Imported geosynthetics and pipe loads equivalent to 10,000 m2 geomembrane or geotextile per load, 450 lin m pipe per load.4. Trips per Hour calculation reflects 2 trips per load, distributed over 9 month construction period, 25 working days/month, 10 hours/day.5. On-site truck movements refer to trips per hour for cut/fill operations within landfill footprint only.


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