APPENDIX A HYDROLOGIC EVALUATION OF LANDFILL PERFORMANCE (HELP) MODEL RESULTS (20)

Transcription

1 APPENDIX A HYDROLOGIC EVALUATION OF LANDFILL PERFORMANCE (HELP) MODEL RESULTS (20)

2 m CLAY COVER ASSESSMENT.txt ****************************************************************************** ****************************************************************************** ** ** ** ** ** HYDROLOGIC EVALUATION OF LANDFILL PERFORMANCE ** ** HELP MODEL VERSION 3.07 (1 NOVEMBER 1997) ** ** DEVELOPED BY ENVIRONMENTAL LABORATORY ** ** USAE WATERWAYS EXPERIMENT STATION ** ** FOR USEPA RISK REDUCTION ENGINEERING LABORATORY ** ** ** ** ** ****************************************************************************** ****************************************************************************** PRECIPITATION DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985p.D4 TEMPERATURE DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985t.D7 SOLAR RADIATION DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985s.D13 EVAPOTRANSPIRATION DATA: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985t.D11 SOIL AND DESIGN DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985s5c.D10 OUTPUT DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985CL.OUT TIME: 11:27 DATE: 4/18/2013 ****************************************************************************** TITLE: CLEAN HARBORS LANDFILL - 5m CLAY COVER ASSESSMENT ****************************************************************************** NOTE: INITIAL MOISTURE CONTENT OF THE LAYERS AND SNOW WATER WERE COMPUTED AS NEARLY STEADY-STATE VALUES BY THE PROGRAM. LAYER TYPE 1 - VERTICAL PERCOLATION LAYER MATERIAL TEXTURE NUMBER 4 THICKNESS = CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-02 CM/SEC NOTE: SATURATED HYDRAULIC CONDUCTIVITY IS MULTIPLIED BY 1.80 FOR ROOT CHANNELS IN TOP HALF OF EVAPORATIVE ZONE. LAYER Page 1

3 m CLAY COVER ASSESSMENT.txt TYPE 3 - BARRIER SOIL LINER MATERIAL TEXTURE NUMBER 29 THICKNESS = CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-06 CM/SEC GENERAL DESIGN AND EVAPORATIVE ZONE DATA NOTE: SCS RUNOFF CURVE NUMBER WAS COMPUTED FROM DEFAULT SOIL DATA BASE USING SOIL TEXTURE # 4 WITH A FAIR STAND OF GRASS, A SURFACE SLOPE OF 2.% AND A SLOPE LENGTH OF 200. METERS. SCS RUNOFF CURVE NUMBER = FRACTION OF AREA ALLOWING RUNOFF = PERCENT AREA PROJECTED ON HORIZONTAL PLANE = HECTARES EVAPORATIVE ZONE DEPTH = 15.0 CM INITIAL WATER IN EVAPORATIVE ZONE = CM UPPER LIMIT OF EVAPORATIVE STORAGE = CM LOWER LIMIT OF EVAPORATIVE STORAGE = CM INITIAL SNOW WATER = CM INITIAL WATER IN LAYER MATERIALS = CM TOTAL INITIAL WATER = CM TOTAL SUBSURFACE INFLOW = 0.00 MM/YR EVAPOTRANSPIRATION AND WEATHER DATA NOTE: EVAPOTRANSPIRATION DATA WAS OBTAINED FROM DETROIT MICHIGAN STATION LATITUDE = DEGREES MAXIMUM LEAF AREA INDEX = 1.00 START OF GROWING SEASON (JULIAN DATE) = 121 END OF GROWING SEASON (JULIAN DATE) = 286 EVAPORATIVE ZONE DEPTH = 15.0 CM AVERAGE ANNUAL WIND SPEED = KPH AVERAGE 1ST QUARTER RELATIVE HUMIDITY = % AVERAGE 2ND QUARTER RELATIVE HUMIDITY = % AVERAGE 3RD QUARTER RELATIVE HUMIDITY = % AVERAGE 4TH QUARTER RELATIVE HUMIDITY = % NOTE: PRECIPITATION DATA WAS SYNTHETICALLY GENERATED USING COEFFICIENTS FOR DETROIT MICHIGAN NORMAL MEAN MONTHLY PRECIPITATION (MM) JAN/JUL FEB/AUG MAR/SEP APR/OCT MAY/NOV JUN/DEC Page 2

4 m CLAY COVER ASSESSMENT.txt NOTE: TEMPERATURE DATA WAS SYNTHETICALLY GENERATED USING COEFFICIENTS FOR DETROIT MICHIGAN NORMAL MEAN MONTHLY TEMPERATURE (DEGREES CELSIUS) JAN/JUL FEB/AUG MAR/SEP APR/OCT MAY/NOV JUN/DEC NOTE: SOLAR RADIATION DATA WAS SYNTHETICALLY GENERATED USING COEFFICIENTS FOR DETROIT MICHIGAN AND STATION LATITUDE = DEGREES ******************************************************************************* AVERAGE MONTHLY VALUES (MM) FOR YEARS 1 THROUGH JAN/JUL FEB/AUG MAR/SEP APR/OCT MAY/NOV JUN/DEC PRECIPITATION TOTALS STD. DEVIATIONS RUNOFF TOTALS STD. DEVIATIONS EVAPOTRANSPIRATION TOTALS STD. DEVIATIONS PERCOLATION/LEAKAGE THROUGH LAYER TOTALS STD. DEVIATIONS Page 3

5 m CLAY COVER ASSESSMENT.txt AVERAGES OF MONTHLY AVERAGED DAILY HEADS (CM) DAILY AVERAGE HEAD ON TOP OF LAYER AVERAGES STD. DEVIATIONS ******************************************************************************* ******************************************************************************* AVERAGE ANNUAL TOTALS & (STD. DEVIATIONS) FOR YEARS 1 THROUGH MM CU. METERS PERCENT PRECIPITATION ( ) RUNOFF ( ) EVAPOTRANSPIRATION ( ) PERCOLATION/LEAKAGE THROUGH ( ) LAYER 2 AVERAGE HEAD ON TOP ( ) OF LAYER 2 CHANGE IN WATER STORAGE ( ) ******************************************************************************* ****************************************************************************** PEAK DAILY VALUES FOR YEARS 1 THROUGH (MM) (CU. METERS) PRECIPITATION RUNOFF PERCOLATION/LEAKAGE THROUGH LAYER AVERAGE HEAD ON TOP OF LAYER SNOW WATER MAXIMUM VEG. SOIL WATER (VOL/VOL) Page 4

6 m CLAY COVER ASSESSMENT.txt MINIMUM VEG. SOIL WATER (VOL/VOL) ****************************************************************************** ****************************************************************************** FINAL WATER STORAGE AT END OF YEAR LAYER (CM) (VOL/VOL) SNOW WATER ****************************************************************************** ****************************************************************************** Page 5

7 44985-HDPE GEOMEMBRANE COVER ASSESSMENT.txt ****************************************************************************** ****************************************************************************** ** ** ** ** ** HYDROLOGIC EVALUATION OF LANDFILL PERFORMANCE ** ** HELP MODEL VERSION 3.07 (1 NOVEMBER 1997) ** ** DEVELOPED BY ENVIRONMENTAL LABORATORY ** ** USAE WATERWAYS EXPERIMENT STATION ** ** FOR USEPA RISK REDUCTION ENGINEERING LABORATORY ** ** ** ** ** ****************************************************************************** ****************************************************************************** PRECIPITATION DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985p.D4 TEMPERATURE DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985t.D7 SOLAR RADIATION DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985s.D13 EVAPOTRANSPIRATION DATA: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985t.D11 SOIL AND DESIGN DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985GEO.D10 OUTPUT DATA FILE: C:\DOCUME~1\MDEJONG\DESKTOP\HELP3\44985GEO.OUT TIME: 14:21 DATE: 4/18/2013 ****************************************************************************** TITLE: CLEAN HARBORS LANDFILL - HDPE COVER ASSESSMENT ****************************************************************************** NOTE: INITIAL MOISTURE CONTENT OF THE LAYERS AND SNOW WATER WERE COMPUTED AS NEARLY STEADY-STATE VALUES BY THE PROGRAM. LAYER TYPE 1 - VERTICAL PERCOLATION LAYER MATERIAL TEXTURE NUMBER 4 THICKNESS = CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-02 CM/SEC NOTE: SATURATED HYDRAULIC CONDUCTIVITY IS MULTIPLIED BY 1.80 FOR ROOT CHANNELS IN TOP HALF OF EVAPORATIVE ZONE. LAYER Page 1

8 44985-HDPE GEOMEMBRANE COVER ASSESSMENT.txt TYPE 1 - VERTICAL PERCOLATION LAYER MATERIAL TEXTURE NUMBER 15 THICKNESS = CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-04 CM/SEC LAYER TYPE 1 - VERTICAL PERCOLATION LAYER MATERIAL TEXTURE NUMBER 2 THICKNESS = CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-02 CM/SEC LAYER TYPE 4 - FLEXIBLE MEMBRANE LINER MATERIAL TEXTURE NUMBER 35 THICKNESS = 0.15 CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-12 CM/SEC FML PINHOLE DENSITY = 5.00 HOLES/HECTARE FML INSTALLATION DEFECTS = HOLES/HECTARE FML PLACEMENT QUALITY = 3 - GOOD LAYER TYPE 3 - BARRIER SOIL LINER MATERIAL TEXTURE NUMBER 16 THICKNESS = 0.60 CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-06 CM/SEC LAYER Page 2

9 44985-HDPE GEOMEMBRANE COVER ASSESSMENT.txt TYPE 1 - VERTICAL PERCOLATION LAYER MATERIAL TEXTURE NUMBER 15 THICKNESS = CM POROSITY = VOL/VOL FIELD CAPACITY = VOL/VOL WILTING POINT = VOL/VOL INITIAL SOIL WATER CONTENT = VOL/VOL EFFECTIVE SAT. HYD. COND. = E-04 CM/SEC GENERAL DESIGN AND EVAPORATIVE ZONE DATA NOTE: SCS RUNOFF CURVE NUMBER WAS COMPUTED FROM DEFAULT SOIL DATA BASE USING SOIL TEXTURE # 4 WITH A FAIR STAND OF GRASS, A SURFACE SLOPE OF 2.% AND A SLOPE LENGTH OF 200. METERS. SCS RUNOFF CURVE NUMBER = FRACTION OF AREA ALLOWING RUNOFF = PERCENT AREA PROJECTED ON HORIZONTAL PLANE = HECTARES EVAPORATIVE ZONE DEPTH = 70.0 CM INITIAL WATER IN EVAPORATIVE ZONE = CM UPPER LIMIT OF EVAPORATIVE STORAGE = CM LOWER LIMIT OF EVAPORATIVE STORAGE = CM INITIAL SNOW WATER = CM INITIAL WATER IN LAYER MATERIALS = CM TOTAL INITIAL WATER = CM TOTAL SUBSURFACE INFLOW = 0.00 MM/YR EVAPOTRANSPIRATION AND WEATHER DATA NOTE: EVAPOTRANSPIRATION DATA WAS OBTAINED FROM DETROIT MICHIGAN STATION LATITUDE = DEGREES MAXIMUM LEAF AREA INDEX = 1.00 START OF GROWING SEASON (JULIAN DATE) = 121 END OF GROWING SEASON (JULIAN DATE) = 286 EVAPORATIVE ZONE DEPTH = 70.0 CM AVERAGE ANNUAL WIND SPEED = KPH AVERAGE 1ST QUARTER RELATIVE HUMIDITY = % AVERAGE 2ND QUARTER RELATIVE HUMIDITY = % AVERAGE 3RD QUARTER RELATIVE HUMIDITY = % AVERAGE 4TH QUARTER RELATIVE HUMIDITY = % NOTE: PRECIPITATION DATA WAS SYNTHETICALLY GENERATED USING COEFFICIENTS FOR DETROIT MICHIGAN NORMAL MEAN MONTHLY PRECIPITATION (MM) JAN/JUL FEB/AUG MAR/SEP APR/OCT MAY/NOV JUN/DEC Page 3

10 44985-HDPE GEOMEMBRANE COVER ASSESSMENT.txt NOTE: TEMPERATURE DATA WAS SYNTHETICALLY GENERATED USING COEFFICIENTS FOR DETROIT MICHIGAN NORMAL MEAN MONTHLY TEMPERATURE (DEGREES CELSIUS) JAN/JUL FEB/AUG MAR/SEP APR/OCT MAY/NOV JUN/DEC NOTE: SOLAR RADIATION DATA WAS SYNTHETICALLY GENERATED USING COEFFICIENTS FOR DETROIT MICHIGAN AND STATION LATITUDE = DEGREES ******************************************************************************* AVERAGE MONTHLY VALUES (MM) FOR YEARS 1 THROUGH JAN/JUL FEB/AUG MAR/SEP APR/OCT MAY/NOV JUN/DEC PRECIPITATION TOTALS STD. DEVIATIONS RUNOFF TOTALS STD. DEVIATIONS EVAPOTRANSPIRATION TOTALS STD. DEVIATIONS PERCOLATION/LEAKAGE THROUGH LAYER TOTALS STD. DEVIATIONS Page 4

11 44985-HDPE GEOMEMBRANE COVER ASSESSMENT.txt PERCOLATION/LEAKAGE THROUGH LAYER TOTALS STD. DEVIATIONS AVERAGES OF MONTHLY AVERAGED DAILY HEADS (CM) DAILY AVERAGE HEAD ON TOP OF LAYER AVERAGES STD. DEVIATIONS ******************************************************************************* ******************************************************************************* AVERAGE ANNUAL TOTALS & (STD. DEVIATIONS) FOR YEARS 1 THROUGH MM CU. METERS PERCENT PRECIPITATION ( ) RUNOFF ( ) EVAPOTRANSPIRATION ( ) PERCOLATION/LEAKAGE THROUGH ( ) LAYER 5 AVERAGE HEAD ON TOP ( ) OF LAYER 4 PERCOLATION/LEAKAGE THROUGH ( ) LAYER 6 CHANGE IN WATER STORAGE ( ) ******************************************************************************* ****************************************************************************** PEAK DAILY VALUES FOR YEARS 1 THROUGH (MM) (CU. METERS) PRECIPITATION Page 5

12 44985-HDPE GEOMEMBRANE COVER ASSESSMENT.txt RUNOFF PERCOLATION/LEAKAGE THROUGH LAYER AVERAGE HEAD ON TOP OF LAYER PERCOLATION/LEAKAGE THROUGH LAYER SNOW WATER MAXIMUM VEG. SOIL WATER (VOL/VOL) MINIMUM VEG. SOIL WATER (VOL/VOL) ****************************************************************************** ****************************************************************************** FINAL WATER STORAGE AT END OF YEAR LAYER (CM) (VOL/VOL) SNOW WATER ****************************************************************************** ****************************************************************************** Page 6

13 44985 Clean Harbors Lambton Landfill Final Cover System HELP Model Analysis April 18, 2013 HELP Model Inputs: WEATHER DATA EVAPOTRANSIPRIATION DATA Nearby City Detroit, Michigan Latitude (worldatlas.com) Evaporative Zone Depth 80 cm (Lambton is known for clayey soils, which generally have a larger evaporative zone depth due to additional capillary suction) Maximum Leaf Area Index 1.0 (poor stand of grass at the site) Growing Season Start Day 121 (default number for Detroit, Michigan) Growing Season End Day 286 (default number for Detroit, Michigan) Average Wind Speed 16 KPH (default number for Detroit, Michigan) First Quarter, Second Quarter, Third Quarter, and Fourth Quarter Relative Humidity 73%, 67%, 71%, and 75%, respectively (default number for Detroit, Michigan) WEATHER DATA PRECIPITATION, TEMPERATURE AND SOLAR RADIATION DATA Precipitation Synthetic Precipitation Nearby City Detroit, Michigan Number of Years of Data 100 Generation Manual Input of Precipitation Data Yes; Temperature Synthetic Temperature Nearby City Detroit, Michigan Number of Years of Data 100 Generation Manual Input of Precipitation Data Yes; Solar Radiation Synthetic Solar Radiation Nearby City Detroit, Michigan Number of Years of Data 100 Generation Station Latitude Degrees SOIL AND DESIGN DATA RUNOFF CURVE NUMBER INFORMATION Help Model Computed CN Slope 2% Slope Length 200 m Soil Texture 4; as per topsoil layer data below Vegetation 3; Fair stand of grass Result

14 Layer Layer Type SOIL AND DESIGN DATA LAYER DATA - 5m CLAY COVER Saturated Layer USCS Hydraulic Rationale Thickness Conductivity Topsoil 1 15 cm SM 1.7 x 10-3 cm/s Topsoil layer as per previously approved Highwest Landfill topsoil. Clay cm CH 6.8 x 10-7 cm/s High plasticity clay, conductivity of 10-7 cm/s as per Appendix F of 2012 Annual Report SOIL AND DESIGN DATA LAYER DATA 1.5 mm HDPE Geomembrane Layer Saturated Layer Layer USCS Hydraulic Type Thickness Conductivity Rationale Topsoil 1 15 cm SM 1.7 x 10-3 cm/s Topsoil layer as per previously approved Highwest Landfill topsoil. Protective 1 35 cm CH 1.7 x 10-5 cm/s On-Site clay material Cover Sand 1 20 cm SW 5.8 x 10-3 cm/s Sand cover over geomembrane. HDPE Geomembrane cm x cm/s Pinhole Density = 5/hectare Install Defects = 10/hectare (fair install quality) Placement Quality = 3 (good install quality) x 10-7 cm/s Geosynthetic Clay Liner Interim Cover 1 60 CH 1.7 x 10-5 cm/s On-Site clay material 2

15 APPENDIX B SENSITIVITY ANALYSIS - LEACHATE CONTROL SYSTEM (20)

16 S.S. PAPADOPULOS & ASSOCIATES, INC. Memorandum From: To: Project: Subject: Christopher J. Neville and Jinhui Zhang Gunther Funk, P. Geo., RWDI SSP-1225 Clean Harbors Lambton Facility proposed expansion: AM1 Revised sensitivity analyses for the leachate control system (LCS) Overview Analyses were developed and documented in May 2014 to investigate the implications of altering the leachate collection system (LCS) design parameters (depth and water level) on the potential performance of Alternative Method 1. This memorandum presents the results of revised analyses that incorporate deepening of the clay plug from 4 m to 5 m. The width of the clay plug has remained unchanged at 5 m. The memorandum is prepared as an appendix to the final Comparative Evaluation Final Report (RWDI, 2014c). The results of the analyses suggest that lowering the depth of the LCS has negligible effect on the hydraulic containment of the waste. Complete containment of the waste is predicted as long as the water level in the LCS is maintained below the long-term average water levels in the Clay Aquitard and the Interface Aquifer. Lowering the water level in the LCS induces increasing amounts of lateral flow and upwards vertical flow from the Interface Aquifer to the LCS and the waste. The flow into the waste discharges ultimately to the LCS. Additional results are presented for cases in which the water level in the Interface Aquifer is reduced by purge well pumping in the Interface Aquifer along the perimeter of the footprint of the site. These results suggest that complex flow patterns may arise when the effects of purge well pumping are considered. If the water level is reduced by 1 to 2 m, seepage through the waste is directed to the LCS. If the water level is reduced by 5 m, seepage through the waste is directed downwards to Interface Aquifer. 90 FROBISHER DR., UNIT 2B,, W ATERLOO, ONTARIO N2V 2A1 TEL: (519) FAX: (519) p:\1225_clean harbors-lambton\ _lcs-sensitivity-analyses\ssp1225_memorandum_lcs-sensitivity-analyses_ docx

17 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: 2 1. Introduction The proposed design of Alternative Method 1 (AM1) specifies that the leachate control system (LCS) would be installed to a depth of 5 m (CRA, 2014) (1). The ground surface elevation varies between about 200 and 201 masl; therefore, the base of the LCS would be set at an elevation of between 195 and 196 masl. In the draft Net Effects Report an operating level of 198 masl was specified for the LCS, so as to have negligible flow between the shallow subsurface and the Interface Aquifer (RWDI, 2014b; Table 2). In the Township (PRT) reviewers comments on the draft Net Effects Report it was suggested that: Standard best practice requires that when a landfill design includes a perimeter collection trench, leachate levels are maintained (by design and approval requirements) at the base of the trench. The PRT reviewers requested a rationale supporting the specification of the design water level for the LCS. The reviewers further recommended that the design of Alternative Method 1 be revised to include an LCS that extends to a minimum depth of 6 m (the PRT reviewers refer to the LCS as the Hydraulic Control Trench, HCT). This memorandum presents the results of revised groundwater modeling analyses conducted to assess the implications of changes in the penetration depth of the LCS into the Clay Aquitard and the operating water level in the LCS. The analyses have been revised to incorporate a lowering of the bottom of the clay plug, from a depth of 4 m to 5 m. Note: 1. A 388 m long portion of the LCS near the processing facility and incinerator would be shallower, extending to a maximum depth of 2 m.

18 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: 3 2. Conceptual model for the sensitivity analyses The starting point for the simulations conducted here is the analysis for AM1 presented in the Comparative Evaluation Final Report (RWDI, 2014c). AM1 is conceived as a build-over of the existing landfill and clay cap. The areas of the Existing Landfill are shown in Figure 1. Following the designation of the pathway analyses presented in Appendix A of the Comparative Evaluation Final Report, the build-over for AM1 corresponds to the areas A-2, A-4 and A-5: Area A-2: Cells 16 and 17; Area A-4: Cell 18 Sub-cells 4-12 and 14; and Area A-5: Cell 18 Sub-cell 15. The elements of the AM1 design are shown in Figure 2 (adapted from Comparative Evaluation Final Report). The construction of AM1 would require excavation of a portion of the cap of the existing landfill and the placement of a granular drainage layer over the residual thickness of the existing cap (Hydraulic Control Layer, HCL). Holes would be extended across the residual cap to allow for a hydraulic connection between the underlying saturated waste and the HCL. The analysis assumes that there is a direct hydraulic connection between the HCL and the underlying waste. The granular drainage layer and the overlying waste are tied into a perimeter leachate collection system. Two elements of the design are examined in the sensitivity analyses: the depth to which the LCS is constructed into the Clay Aquitard, and the water level that is maintained in the LCS. A leakage rate of 3 mm/yr through the engineered cover is specified, based on the results of analyses conducted for the Conceptual Design Report (CRA, 2013). The engineered cover would extend over the clay plug, so that the clay plug would not be expected to deteriorate through time. The results of an extensive tracer test conducted by L.D. McKay suggest that there is negligible movement of solutes below a depth of 5 m at the Clean Harbors Lambton Facility (see in particular McKay et al., 1993; Figures 3, 4 and 5). For the present analyses, the thickness of the Active Aquitard is specified as 6 m, which is divided into upper and lower portions that are 3 m thick.

19 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: 4 A-1: Pre-1986 Landfill A-2: Cell 16 and Cell 17 A-3: Cell 18, Sub-Cells 1 and 2 A-4: Cell 18, Sub-Cells 4-12 and Sub-Cell 14 A-5: Cell 18, Sub-Cell 15 Figure 1. Areas of existing landfill considered in the pathway analyses

20 To: Gunther Funk, P. Geo., RWDI Page: 5 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 2. Schematic representation of AM1 Cells 16 and 17 build-over

21 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: 6 3. The numerical groundwater flow model A high-resolution numerical model has been developed for the sensitivity analyses. The model has been developed using the comprehensive finite-element simulator FEFLOW version 6.2 (Diersch, 2014). The finite element method has been selected to support a precise representation of the geometry of details of the proposed design. FEFLOW is used here to simulate steady groundwater flow in a vertical cross-section. The structure of the finite element model is shown in Figure 3. The top surface of the model is placed at an elevation of 201 masl. The new waste extends above this elevation; the portion above 201 masl is represented implicitly by the specified leakage through the engineered cover. As indicated in the previous section, it is assumed here that the HDPE geomembrane of the engineered cover will extend over the clay plug and be keyed into the outside edge of the plug. The finite element mesh is shown in Figure 4. The mesh contains a total of 229,415 triangular elements. An area of fine resolution is included at the LCS to provide flexibility in representing a range of penetration depths. The boundary conditions for the model are indicated in Figure 5. The waste above the ground surface outside of the landfill is represented implicitly by the leakage through the engineered cover. The bottom elevation of the perimeter drainage ditch is set at masl. The perimeter ditch is represented by constrained constant-head conditions set at masl. In effect, these conditions specify that that the ditch is pumped dry. If the groundwater model predicts water levels in excess of masl, the seepage into the ditched is drained off. If the groundwater model predicts water levels at or below masl, there is no flow to or from the ditch. The model extends laterally about 70 m from the LCS and 60 m from the perimeter drainage ditch. It is assumed that at this distance conditions in the Clay Aquitard and the Interface Aquifer are close to the presently observed long-term levels of 198 masl.

22 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: 7 The hydraulic conductivity values specified in the model are illustrated in Figure 6. The values listed below are consistent with the draft Geology and Hydrogeology Existing Conditions Report (RWDI, 2014a) and the Comparative Evaluation Final Report (RWDI, 2014c) or with typical literature values (Freeze and Cherry, 1979). Waste: m/s; Granular drainage layer and LCS: m/s; Clay plug: m/s; HDPE geomembrane: m/s; Upper portion of the Active Aquitard: m/s; Lower portion of the Active Aquitard: m/s; Clay Aquitard: m/s; and Interface Aquifer: m/s.

23 To: Gunther Funk, P. Geo., RWDI Page: 8 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 3. Structure of the numerical groundwater flow model

24 To: Gunther Funk, P. Geo., RWDI Page: 9 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 4. Finite element mesh

25 To: Gunther Funk, P. Geo., RWDI Page: 10 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 5. Groundwater model boundary conditions

26 To: Gunther Funk, P. Geo., RWDI Page: 11 S.S. PAPADOPULOS & ASSOCIATES, INC. Hydraulic conductivity values in m/s Figure 6. Hydraulic conductivity distribution

27 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Results of the sensitivity analyses The scenarios considered in the sensitivity analyses are summarized below. For completeness, the case of the LCS not actively pumped is simulated as Case 1. Cases 2 through 4 are designed to examine the implications of decreasing the depth of the LCS from masl to 192 masl, with water levels in the LCS ranging from 198 masl to 192 masl. The water level in the Interface Aquifer is kept at its present average elevation of 198 masl. The effects of purge wells operating in the Interface Aquifer are investigated in Cases 6, 7 and 8. Case Description LCS extends to m; LCS is not actively pumped LCS extends to m; Water level in LCS maintained at 198 masl LCS extends to m; Water level in LCS maintained at 196 masl LCS extends to 192 m; Water level in LCS maintained at 196 masl LCS extends to 192 m; Water level in LCS maintained at 192 masl LCS extends to m; Water level in LCS maintained at 196 masl Water level in the Interface Aquifer reduced from 198 masl to 197 masl LCS extends to m; Water level in LCS maintained at 196 masl Water level in the Interface Aquifer reduced from 198 masl to 196 masl LCS extends to m; Water level in LCS maintained at 196 masl Water level in the Interface Aquifer reduced from 198 masl to 193 masl

28 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 1: LCS extends to masl; LCS not pumped The simulated water levels for Case 1 are shown in Figure 7. The dashed blue line in Figure 7 denotes the elevation of the water table. A uniform water level in the waste and the HCL of masl is predicted. The water level declines across the clay plug, reflecting the relatively low hydraulic conductivity specified for the plug. Beyond the clay plug the water level declines gradually to the lateral boundary of the model. The gentle gradient is sufficient to transmit the leakage through the engineered cover to the lateral boundary. The simulated water is just below the bottom of the perimeter drainage ditch. The directions of water flow from the waste are illustrated in Figure 8. The flow directions are calculated with a particle tracking analysis. A flow divide is predicted within the existing waste. Below an elevation of about masl flow is directed downwards to the Interface Aquifer. Above an elevation of masl, the seepage through the waste is directed upwards towards the Upper portion of the Active Aquitard.

29 To: Gunther Funk, P. Geo., RWDI Page: 14 S.S. PAPADOPULOS & ASSOCIATES, INC. Q = 0.0 Figure 7. Case 1 water levels (masl) - no pumping from LCS

30 To: Gunther Funk, P. Geo., RWDI Page: 15 S.S. PAPADOPULOS & ASSOCIATES, INC. Divide at masl Figure 8. Case 1 flow directions from the waste

31 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 2: LCS extends to masl; water level in LCS maintained at 198 masl The layout of the analysis for Case 2 is shown in Figure 9. The base of the LCS is set at an elevation of masl and the water level in the LCS is maintained 2.5 m higher, at an elevation of 198 masl. The simulated water levels for Case 2 are not presented as they are essentially uniform at a level of 198 masl. A small rise in the water level in the upper waste is sufficient to transmit the 3 mm/yr leakage through the engineered cover to the LCS. The calculated flow into the LCS is 0.26 L/day per metre length into the plane of the section. This is identical to the accumulated leakage through the cover along its 32 m of length in the model. The directions of water flow from the waste are illustrated in Figure 10. The results of the particle tracking calculations indicate that all of the water passing through the waste discharges to the LCS.

32 To: Gunther Funk, P. Geo., RWDI Page: 17 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 9. Model structure for Case 2 - water level in LCS held at 198 masl

33 To: Gunther Funk, P. Geo., RWDI Page: 18 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 10. Case 2 flow directions

34 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 3: LCS extends to masl; water level in LCS lowered to 196 masl The layout of the analysis for Case 3 is shown in Figure 11. The base of the LCS is kept at an elevation of masl but the water level in the LCS is lowered to just above its base, to an elevation of 196 masl. The simulated water levels for Case 3 are presented in Figure 12. The water level in the waste and granular drainage layer is 196 masl, controlled by the water level in the LCS. The calculated flow into the LCS is 0.54 L/day/m, about double the accumulated leakage through the engineered cover. The directions of water flow from the waste are illustrated in Figure 13. Fundamental differences with respect to the Case 2 are the prediction of inflows from the lateral boundary, and upwards flow from the Interface Aquifer into the waste. The results of the particle tracking calculations indicate that the lateral flow from the boundary is directed to either the LCS or the waste. The flow into the waste discharges to the LCS.

35 To: Gunther Funk, P. Geo., RWDI Page: 20 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 11. Model structure for Case 3 - water level in LCS held at 196 masl

36 To: Gunther Funk, P. Geo., RWDI Page: 21 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 12. Case 3 simulated water levels

37 To: Gunther Funk, P. Geo., RWDI Page: 22 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 13. Case 3 flow directions

38 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 4: LCS lowered to 192 masl; water level in LCS maintained at 196 masl The layout of the analysis for Case 4 is shown in Figure 14. The base of the LCS is lowered to an elevation of 192 masl with the water level in the LCS maintained at 196 masl. The simulated water levels for Case 4 are presented in Figure 15. The water level in the waste and granular drainage layer is 196 masl, controlled by the water level in the LCS. The water levels are essentially the same as those predicted for Case 3. The calculated flow into the LCS is 0.54 L/day/m, almost identical to the flow estimated for Case 2. The directions of water flow from the waste are illustrated in Figure 16. The results of the particle tracking calculations indicate that groundwater is directed from the Interface Aquifer to the waste and the lateral boundary contributes to either the LCS or the waste. All of the seepage into the waste discharges to the LCS. The results from Case 4 indicate that deepening the LCS while maintained the water level has no effect on the performance of the containment system.

39 To: Gunther Funk, P. Geo., RWDI Page: 24 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 14. Model structure for Case 4 LCS extended to 192 masl

40 To: Gunther Funk, P. Geo., RWDI Page: 25 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 15. Simulated water levels for Case 4

41 To: Gunther Funk, P. Geo., RWDI Page: 26 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 16. Case 4 flow directions

42 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 5: LCS lowered to 192 masl; water level in LCS maintained at 192 masl The layout of the analysis for Case 5 is shown in Figure 17. The base of the LCS is set at 192 masl with the water level in the LCS lowered to its base. The simulated water levels for Case 5 are presented in Figure 18. The water level in the waste and granular drainage layer declines to 192 masl, controlled by the water level in the LCS. The calculated flow into the LCS is 1.02 L/day/m, more than four times the estimated flow for Case 2. The directions of water flow from the waste are illustrated in Figure 19. The results of the particle tracking calculations indicate that the flow from the lateral boundary is directed to the LCS. Flow upwards from the Interface Aquifer is directed upwards to either the LCS or to the waste. The flow into the waste discharges to the LCS. The results from Case 5 indicate that deepening the LCS and lowering the water level in the LCS has no effect on the containment of the waste, but the lateral flow into the site and vertical flow from the Interface Aquifer are increased.

43 To: Gunther Funk, P. Geo., RWDI Page: 28 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 17. Model structure for Case 5 LCS water level fixed at 192 masl

44 To: Gunther Funk, P. Geo., RWDI Page: 29 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 18. Simulated water levels for Case 5

45 To: Gunther Funk, P. Geo., RWDI Page: 30 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 19. Case 5 flow directions

46 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 6: LCS extends to masl; water level in LCS maintained at 196 masl; Water level in the Interface Aquifer reduced to 197 masl to account for purge well pumping S.S. Papadopulos & Associates, Inc. has conducted conceptual-level analyses of the operation of purge wells in the Interface Aquifer beneath the Existing Landfill (SSP&A, 2014). The analyses suggest that hydraulic containment may be achieved in the Interface Aquifer by pumping from two wells located along the perimeter of the Existing Landfill. The predicted drawdowns vary across the site. The maximum predicted drawdown within the footprint of the Existing Landfill is about 5 m; the maximum predicted drawdown beneath the perimeter ditch is about 2 m, with a maximum drawdown of about 3 m. Three cases are analyzed to bracket the likely range of water levels in the Interface Aquifer with purge wells operating. For all three cases the base of the LCS is set at masl with the water level in the LCS just above the base. The layout of the analysis for Case 6 is shown in Figure 20. The water level in the Interface Aquifer at the perimeter of the site is reduced by 1 m from current long-term average levels, to an elevation of 197 masl. The simulated water levels for Case 6 are presented in Figure 21. The predicted flow into the LCS is 0.50 L/d/m length. The directions of groundwater flow are illustrated in Figure 22. Lowering the water level in the Interface Aquifer by 1 m below the perimeter ditch gives rise to a relatively complex flow pattern in the groundwater flow system. A portion of the lateral flow through the Active Aquitard is directed towards the landfill, while the remainder is ultimately directed downwards to the Interface Aquifer. Seepage is directed inwards to the waste, with the seepage discharging to the LCS.

47 To: Gunther Funk, P. Geo., RWDI Page: 32 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 20. Model structure for Case 6 Interface Aquifer water level reduced locally to 197 masl

48 To: Gunther Funk, P. Geo., RWDI Page: 33 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 21. Simulated water levels for Case 6

49 To: Gunther Funk, P. Geo., RWDI Page: 34 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 22. Case 6 flow directions

50 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 7: LCS extends to masl; water level in LCS maintained at 196 masl; Water level in the Interface Aquifer reduced to 196 masl to account for purge well pumping The layout of the analysis for Case 7 is shown in Figure 23. The only change with respect to Case 6 is a lowering of the water level in the Interface Aquifer below the perimeter ditch by a further 1 m, to an elevation of 196 masl. The simulated water levels for Case 6 are presented in Figure 24. The predicted flow into the LCS is reduced from 0.50 L/d/m length to 0.46 L/d/m length. The directions of groundwater flow are illustrated in Figure 25. The groundwater divide that below the clay plug is more clearly developed. A large zone of nearly stagnant conditions develops within and below the landfill. Seepage is still directed inwards to the waste; flow through the waste is directed upwards to the LCS.

51 To: Gunther Funk, P. Geo., RWDI Page: 36 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 23. Model structure for Case 7 Interface Aquifer water level reduced locally to 196 masl

52 To: Gunther Funk, P. Geo., RWDI Page: 37 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 24. Simulated water levels for Case 7

53 To: Gunther Funk, P. Geo., RWDI Page: 38 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 25. Case 7 flow directions

54 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: Case 8: LCS extends to masl; water level in LCS maintained at 196 masl; Water level in the Interface Aquifer reduced to 193 masl to account for purge well pumping The layout of the analysis for Case 8 is shown in Figure 26. For this third scenario involving purge well pumping from the Interface Aquifer, the only change with respect to Case 6 is a further lowering of the water level in the Interface Aquifer below the perimeter ditch by 3 m, to an elevation of 193 m. The simulated water levels for Case 8 are presented in Figure 27. The predicted flow into the LCS is reduced from 0.50 L/d/m length for Case 6 to 0.33 L/d/m length. The directions of water flow are illustrated in Figure 28. For this case, the bulk of the groundwater flow is directed downwards to the Interface Aquifer. The seepage through the waste is directed downwards to the Interface Aquifer rather than the LCS. The flow into the LCS originates in the Active Aquitard between the LCS and the drainage ditch.

55 To: Gunther Funk, P. Geo., RWDI Page: 40 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 26. Model structure for Case 8 Interface Aquifer water level reduced locally to 193 masl

56 To: Gunther Funk, P. Geo., RWDI Page: 41 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 27. Simulated water levels for Case 8

57 To: Gunther Funk, P. Geo., RWDI Page: 42 S.S. PAPADOPULOS & ASSOCIATES, INC. Figure 28. Case 8 flow directions

58 S.S. PAPADOPULOS & ASSOCIATES, INC. To: Gunther Funk, P. Geo., RWDI Page: References Conestoga-Rovers & Associates (CRA), 2014: Conceptual Design Report, Clean Harbors Canada Inc., Lambton Landfill Expansion Environmental Assessment, July 2013 draft. Diersch, H.-J. G., 2014: FEFLOW: Finite Element Modeling of Flow, Mass and Heat Transport in Porous and Fractured Media, Springer-Verlag, Berlin, Germany. Freeze, R.A., and J.A. Cherry, 1979: Groundwater, Prentice-Hall, Inc., Englewood Cliffs, New Jersey. McKay, L.D., R.W. Gillham, and J.A. Cherry, 1993: Field experiments in a fractured clay till, 2. Solute and colloid transport, Water Resources Research, vol. 29, no. 12, pp RWDI AIR Inc. (RWDI), 2014a: Geology and Hydrogeology Existing Conditions Report, submitted to Clean Harbors Canada, Inc., Lambton Landfill Expansion Environmental Assessment, revised October RWDI AIR Inc. (RWDI), 2014b: Geology & Hydrogeology Net Effects Analysis & Comparative Evaluation Report, submitted to Clean Harbors Canada, Inc., Lambton Landfill Expansion Environmental Assessment, January 2014 draft. RWDI AIR Inc. (RWDI), 2014c: Comparative Evaluation Final Report, submitted to Clean Harbors Canada, Inc., Lambton Landfill Expansion Environmental Assessment, October S.S. Papadopulos & Associates, Inc. (SSP&A), 2014: Clean Harbors Lambton facility: Analysis of purge wells beneath the existing landfill, memorandum prepared for Gunther Funk, RWDI, May 1, 2014.