2008 Construction Activities Summary Report Cell 18, Lambton Facility Clean Harbors, Corunna, Ontario

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2 Reference No. T (25) November 11, 2009 Mr. Tim Bechard General Manager, Landfill Clean Harbors Canada, Inc Telfer Road, RR #1 Corruna, ON N0N 1G0 Re: 2008 Construction Activities Summary Report Cell 18, Lambton Facility Clean Harbors, Corunna, Ontario Dear Mr. Bechard: The enclosed report presents our summary of the 2008 construction activities carried out in Cell 18 at the above referenced site, and provides the results of field inspections and laboratory analyses of the clay material excavated from Trenches 1201/1202 used in the cap construction of Subcells 1, 2 and 3, and the cap key construction at Subcell 12. We trust that this information meets with your approval. Please do not hesitate to contact us, should any questions arise. Yours very truly, INSPEC-SOL INC. Bruce Polan, M.A.Sc., P. Eng. Branch Manager, Waterloo bp/cr/25

3 Reference No. T (25) 1.0 INTRODUCTION CONSTRUCTION ACTIVITIES Trench 1201 and 1202 Excavation Construction of Cap Key On Subcell Partial Cap Construction on Subcells 1, 2 and LABORATORY RESULTS CONCLUSIONS AND RECOMENDATIONS...7

4 Reference No. T (25) FIGURES FIGURE 1.1 Cell 18 FIGURE Construction Activities FIGURE 2.2 Pre-Construction Contours-Partial Cap Construction, Subcell 1, 2 and 3 FIGURE 2.3 Post-Construction Contours-Partial Cap Construction, Subcell 1, 2 and 3 TABLES TABLE 3.1 TABLE 3.2 TABLE 3.3 Summary Of Geotechnical Laboratory Results-Excavation of Trenches 1201/1202 and Cap Key Subcell 12 Summary Of Geotechnical Laboratory Results-Test Pads and Partial Clay Cap Subcell 1 To 3 Comparison of 2008 Laboratory Results with Recommended Clay Properties

5 Reference No. T (25) APPENDICES APPENDIX A APPENDIX B APPENDIX C APPENDIX D APPENDIX E Daily Field Reports Photographic Record Compaction Test Results Inspec-Sol Laboratory Testing Results CEC and Total Carbonate Test Reports by ALS Laboratory Group

6 2008 CONSTRUCTION ACTIVITIES SUMMARY REPORT CELL 18 Lambton Facility, Corunna, Ontario Prepared For: Clean Harbors Canada, Inc. Date: November 11, 2009 Reference: T (25)

7 Reference No. T (25) INTRODUCTION This report presents the results of inspection, monitoring and testing of the 2008 construction activities for Cell 18 Clean Harbors Canada, Inc. (Clean Harbors) Lambton Facility (Site) Landfill, in St. Clair Township, County of Lambton, Ontario. Cell 18 and the surrounding area are shown on Figure 1.1. Geotechnical monitoring and inspection is carried out on at least a monthly basis for the Cell 18 area, and more frequently during construction activities. Semi-annual summary reports are prepared for the geotechnical monitoring and inspection activities and these reports are on file with Clean Harbors Canada, Inc. The following routine monitoring tasks were carried out by Inspec-Sol over the subject period: visual inspections of Cell 18, which entailed, at a minimum, visual inspection of the top of the slopes, base of the excavation, side slopes, stormwater and leachate ponds and other items deemed appropriate by the Geotechnical Engineer; quarterly inspection by the Geotechnical Engineer of Cell 18 and screening berm slope stability issues; and monthly monitoring and interpretation of the existing geotechnical instrumentation around the perimeter of Cell 18, including slope inclinometers, heave gauges, survey pins, and pneumatic piezometers. The following construction activities were completed in 2008: excavation of Trenches 1201/1202; cap key construction along the north and east sides of Subcell 12; partial clay cap construction on Subcells 1, 2 and 3; Inspec-Sol performed the following tasks over the construction period: full-time or part-time oversight during trench excavations and clay cap construction by a soil technologist, including compaction and moisture content tests using a nuclear density gauge (discussed in Section 2.0); and

8 Reference No. T (25) 2 laboratory testing of representative samples of the excavated clay, and the installed cap key/clay cap (results of the tests are discussed in Section 3.0); Daily field reports of progress and site activities are presented in Appendix A. A photographic record of site activities is presented in Appendix B. Compaction test summary reports are presented in Appendix C, and laboratory test results are presented in Appendices D and E. 2.0 CONSTRUCTION ACTIVITIES The following sections discuss the 2008 construction activities in the order of the sequence of the activities. Figure 2.1 shows the location of the 2008 construction activities. 2.1 Trench 1201 and 1202 Excavation Trenches 1201 and 1202 were excavated over the period of September 25, 2008 to November 12, The design drawings for the trench excavations were prepared by Inspec-Sol. Inspec-Sol was present during the trench excavations to monitor the excavation activities and inspect the sides and base of the excavations. Figure 2.1 shows the location of Trenches 1201 and Photographs are included in Appendix B. The trench excavations were completed November 12, The bases of the trenches were inspected by Inspec-Sol personnel, and were found to be dry and competent, with no wet areas, evidence of seepage or cracks, or sand seams at the design elevation of 182 metres (m) above mean sea level (amsl). The excavated clay from the trenches was used in the construction of the partial cap key along the north and east sides of Subcell 12, and in the partial clay cap construction on Subcells 1, 2 and 3. Approximately 35,000 cubic metres (m 3 ) of clay was excavated as of November 12, As part of the excavation activities for the trenches, the existing piezometer 0266 within the excavation footprint was decommissioned on September 4, 2008 prior to commencement of the trench excavations. A new slope inclinometer and a piezometer nest 0869 was installed along the eastern side of Trenches 1201 and 1202 during September 2, 2008 to September 8, The details of the new piezometer and slope inclinometer are provided in the Semiannual Geotechnical Monitoring and Inspection Report.

9 Reference No. T (25) Construction of Cap Key On Subcell The installation of the cap key along the north and east sides of Subcell 12 was started on October 9, 2008 and completed on October 20, The cap key was constructed with grey clay excavated from the Trenches 1201/1202 in Subcell 12. The purpose of the cap key is to provide a tie-in for the future clay cap to be constructed on Subcell 12. Approximately 9,700 m 3 of grey clay was placed for the cap key at these locations. Prior to cap key construction, two samples of grey clay were collected from the source excavation of Trenches 1201/1202 at elevations of 191 m amsl and 194 m amsl. One clay sample was collected from the cap key (Subcell 12) at the time of its installation at an elevation of 200 m amsl. The clay samples were tested for geotechnical index properties. The laboratory geotechnical test results are discussed in Section 3.0. Recommendations for clay cap and key construction were provided in the Inspec-Sol report entitled Interim Cap Construction Summary Report, Subcells 2 and 3, Cell 18, which was submitted to Clean Harbors in June 2006, and subsequently to the Ministry of Environment (MOE) for their review. The recommended construction specifications are reproduced below: construct with loose lifts of 200 mm or less; have a maximum clod size of 100 mm. Clods with diameter larger than 100 mm should be mechanically pulverized prior to compaction; be compacted in the range of 91 percent to 95 percent SPMDD as determined by ASTM D698 (standard Proctor); be placed with a minimum soil moisture content that shall not be less than two percent above the optimum moisture content; have a maximum permeability of cm/s; be adequately protected from damage due to desiccation, freeze/thaw cycles, wet/dry cycles, and the intrusion of objects during construction of the cap; have quality control testing of the constructed lifts performed to determine the density and moisture content according to ASTM D2922 and ASTM D3017 (nuclear methods). The location of the individual tests shall be adequately spaced to represent the constructed area; and be scarified to a nominal depth of 100 mm prior to placing soil for the next lift.

10 Reference No. T (25) 4 Inspec-Sol witnessed the construction of the cap key and tested compaction during construction. The detailed compaction test results are presented in Appendix C. In general, the construction of the cap key was in accordance with these recommendations, and the compaction and moisture content of the cap key met the recommended specifications. The quality control of the cap key comprised visual inspections of the subgrade material, verifying the lift thickness, determining and monitoring of in-situ moisture contents and dry densities, and collecting representative bulk samples from the excavation of trenches 1201/1202 and cap key at the locations of subcell 12 for laboratory testing. The field results are included in Appendix C. The field moisture contents measured with the nuclear densitometer ranged from 19.5 % to 22.3 %, compared to the optimum moisture content of approximately 15.4 %. The field compaction was measured to range from 91 % to 96 %. Generally, the measured degree of compaction and in-situ moisture contents met the specifications listed above. 2.3 Partial Cap Construction on Subcells 1, 2 and 3 A portion of the landfill cap along the east side of Subcell 3 was constructed during October 24, 2008 to November 12, Prior to the construction of this portion of the clay cap on Subcell 3, two test pads were constructed on October 15, Test Pad 1 was constructed using grey clay, and Test Pad 2 was constructed using mixed grey-brown clay. These test pads were constructed using 300 mm lifts to evaluate the use of a slightly thicker lift (300 mm vs. 200 mm current specification) and its results on the in situ permeability (hydraulic conductivity) of the placed cap material. The results of the laboratory permeability tests and other index testing on the test pads are discussed in Section 3.0. The partial clay cap on Subcell 3 was constructed with primarily grey clay with an exception of a section of mixed grey-brown clay excavated from the Trenches 1201/1202 excavations, in general accordance with the cap specifications discussed in Section 2.2. Inspec-Sol prepared the construction drawings for the cap work. The clay cap was compacted consistent with the cap specifications as listed in Section 2.2, to achieve a hydraulic conductivity of 1.0 x 10-7 cm/s or less. Inspec-Sol monitored the construction of the cap, and provided quality control and compaction testing services during cap construction. Compaction testing using the nuclear densiometer indicated that the clay cap was compacted in the range of 93 % to 99 %, with moisture contents in the range of 18.8 % and 23.6 %.

11 Reference No. T (25) 5 Approximately 8,400 m 3 of clay was placed during the partial cap construction. The field inspection reports are included in Appendix A, photographs are included in Appendix B, and compaction test results are included in Appendix C. Figure 2.2 shows pre-construction contours, and Figure 2.3 shows contours after completion of the partial cap. This portion of the clay cap on Subcell 3 is was constructed to about elevation 199 to 200 m amsl. Additional clay cap will have to be placed in this area to reach the final cap grades. A portion of the landfill cap was also constructed in the southeast side of Subcell 1 and southwest side of Subcell 2 from November 27, 2008 to December 4, 2008, at the location shown on Figure 2.2. This portion of the cap was constructed using stockpiled grey clay from the north end of Subcell 1. The clay cap was compacted consistent with the cap specifications as listed in Section 2.2, to achieve a hydraulic conductivity of 1.0 x 10-7 cm/s or less. Inspec-Sol monitored the construction of the cap, and provided quality control and compaction testing services during cap construction. Compaction testing using the nuclear densiometer indicated that the clay cap was compacted in the range of 92 % to 96 %, with moisture contents in the range of 17.6 % to 23.4 %. Approximately 5,100 m 3 of clay was placed during the partial cap construction. The field inspection reports are included in Appendix A, photographs are included in Appendix B, and compaction test results are included in Appendix C. Figure 2.2 shows pre-construction contours, and Figure 2.3 shows contours after completion of the partial caps. Additional cap material will be required to reach the final cap elevations in this area. 3.0 LABORATORY RESULTS Inspec-Sol carried out a detailed geotechnical laboratory testing program to evaluate the properties of the excavated grey and grey-brown mixed clay used in cap key and cap construction. The testing program comprised of testing a total of twenty-four (24) representative samples including the clay samples collected from the excavation trenches, and during cap/cap key construction. These samples were tested for the following: in situ moisture content tests; grain size analysis (including hydrometer test); Atterberg limit test;

12 Reference No. T (25) 6 shrinkage limit tests; standard Proctor tests; triaxial hydraulic conductivity (permeability) tests; cation exchange capacity (CEC) tests using the ammonium acetate method; and total carbonate tests. The detailed laboratory test results for the geotechnical index tests performed by Inspec-Sol are presented in Appendix D. Appendices E present the CEC and total carbonate test results carried out by ALS Laboratory Group (ALS) in Waterloo. A summary of the laboratory results is provided in Table 3.1 and Table 3.2. Recommendations for the clay properties that is used in the cap construction were provided in the 2006 Interim Cap Construction Summary Report, and are summarized below: percentage fines (percent passing No. 200 sieve) 50 percent; percentage of clays (particle size smaller than 2µm) 25 percent; plasticity index (PI): 10 percent PI 25 percent; Liquid Limit (LL): 36 percent; Percentage Gravel (percent retained on No. 4 sieve) 10 percent; largest particle size 25 mm; activity: minimum 0.3, maximum 0.45 (inactive clay classification); Cation Exchange Capacity (CEC): minimum 6, maximum 15 meq/100 g soil (EPA 9080 Method); maximum hydraulic conductivity of cm/s; and Total Carbonates 10 percent. A summary of the average results of the 24 samples tested compared to the specifications is presented in Table 3.3. The tested clay generally met the above requirements, with the exception of activity, which ranged from 0.30 to 0.50 in comparison to the specified 0.3 to 0.45, and CEC, which was found to range from about 4.6 to 6.0 meq/100 g, in comparison to the recommended range of 6 to 15 meq/100 g. However, this did not affect the results of measured hydraulic conductivities, which averaged below the maximum of cm/s. CEC is an indicator of the potential for the clay to contain a swelling mineral known as smectite. As discussed in detail in the 2006 Interim Cap Construction Summary Report, high

13 Reference No. T (25) 7 CEC values exceeding 15 meq/100 g are undesirable as they indicate that the clay contains excessive smectite, and would be prone to shrinking and swelling behaviour, which could result in the formation of cracks in the final cap. However, low CEC values are not an indicator of this behaviour, and likely reflect the presence of non-swelling minerals such as calcium carbonate. For a detailed discussion of this issue, the reader is referred to the 2006 Interim Cap Construction Summary Report. A review of the test results indicate that the activity of the tested clay samples is generally in the acceptable range of 0.3 to 0.45 however, a slightly higher values of 0.49 and 0.50 was tested for the two samples of clay used in clay cap on Subcell 2 and Subcell 3. Similarly the liquid limit of the clay was tested to be lower than the specified maximum limit of 36 %, except at two locations, which was measured to be 38 %. Based on the geotechnical index testing performed on the clay samples, the clay used for cap and cap key construction exceeds the targeted hydraulic conductivity of cm/s, has a low swell potential, and is considered acceptable for use in cap construction. 4.0 CONCLUSIONS AND RECOMENDATIONS Based on the results discussed in the previous sections of the report, the following conclusions are provided: Trenches 1201 and 1202 were excavated to the design elevation 182 m amsl. The bases of the trenches were competent with no evidence of sand seams or wet areas. The excavated trenches were used for temporary leachate storage and waste placement after completion of their excavation. The cap key along the northern side of Subcell 11 and along northeast/east side of Subcell 12 was constructed in general conformance with the design specifications and drawings prepared by Inspec-Sol. The partial clay cap along the southern strip of Subcells 1, 2 and eastern limits of Subcell 3 was constructed in general conformance with the design specifications and drawings prepared by Inspec-Sol.

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21 TABLE 3.1 CONSTRUCTION ACTIVITIES 2008 SUMMARY OF GEOTECHNICAL LABORATORY RESULTS EXCAVATION OF TRENCH 1201/1202, AND CAP KEY CONSTRUCTION, SUBCELL 12 CLEAN HARBORS LAMBTON FACILITY, CORUNNA, ONTARIO page 1 of 1 Sample Location Sample Type Sample Depth (lift/elev.) Sample Date Sample Number Particle Size Distribution % Gravel % Sand % Silt % Passing No. 200 Mesh % clay (< mm) Liquid Limit (LL) Atterberg Limits (%) Plastic Limit (PL) Plasticity Index (PI) Shrinkage Limit (SL) Activity (1) Swell Potential (2) (%) Standard Proctor Maximum Dry Density (kg/m 3 ) Optimum Moisture (%) Moisture Content (%) Remoulded Samples Percent Compaction (%) Permeability (cm/sec) ALS LABORATORIES Cation Exchange Capacity (3) (meq/100 g) Total Carbonate (%) Grey Clay - Trench 1201 / 1202 Bulk 194 m amsl September 25, 2008 WL m amsl October 9, 2008 WL E E Cap Key - Subcell 12 Bulk 200 m amsl October 23, 2008 WL E Average Value: E Notes: (1) Activity is the ratio of PI divided by percent clay. (2) Swell potential is estimated using S=( ) (PI) 2.44,where PI is plasticity index, and S is percent of axial swell under 6.9 kpa pressure (Das, 1990a) (3) Ammonium Acetate Method T RPT 25

22 TABLE CONSTRUCTION ACTIVITIES SUMMARY OF GEOTECHNICAL LABORATORY RESULTS PARTIAL CLAY CAP CONSTRUCTION SUBCELL 1, 2 AND 3, CELL 18 CAP CONSTRUCTION CLEAN HARBORS LAMBTON FACILITY, CORUNNA, ONTARIO page 1 of 1 Sample Location Grey Clay - Test Pad #1 Grey-Brown Mixed Clay - Test Pad # 2 Sample Type Bulk Shelby Bulk Shelby Sample Depth (lift/elev.) Sample Date Sample Number % Gravel Particle Size Distribution % Sand % Silt % Passing No. 200 Mesh % clay (< mm) Liquid Limit (LL) Atterberg Limits (%) Plastic Limit (PL) Plasticity Index (PI) Shrinkage Limit (SL) Activity (1) Swell Potential (2) (%) Standard Proctor Maximum Dry Density 1st lift (300 mm) October 15, 2008 WL nd lift (600 mm) October 15, 2008 WL nd lift (600 mm) North Side October 15, 2008 WL A E nd lift (600 mm) South Side October 15, 2008 WL B E rd lift (900 mm) North Side October 17, 2008 WL E rd lift (900 mm) South Side October 17, 2008 WL E st lift (300 mm) October 15, 2008 WL rd lift (600 mm) October 15, 2008 WL nd lift (600 mm) South Side October 15, 2008 WL C E nd lift (600 mm) North Side October 15, 2008 WL D E rd lift (900 mm) South Side October 17, 2008 WL E rd lift (900 mm) North Side October 17, 2008 WL E (kg/m 3 ) Optimum Moisture (%) Moisture Content (%) Shelby Tube Samples Dry Density (kg/m 3 ) Permeability (cm/sec) ALS LABORATORIES Cation Exchange Capacity (3) (meq/100 g) Total Carbonate (%) Clay Cap Sub Cell - 3 Grey Clay Cap Sub Cell - 1 & 2 Bulk & Shelby Bulk Shelby Tube 198 m amsl (South Side) October 31, 2008 November 6, m amsl (North Side) November 6, 2008 WL 1117 WL E WL WL E m amsl (South Side) November 12, 2008 WL E m amsl (Southwest SC-2) December 3, 2008 WL m amsl (Southside SC-2) December 4, 2008 WL m amsl (Southwest SC-2) November 28, 2008 WL E m amsl (Southwest SC-2) December 3, 2008 WL E Average Value: E (1) Activity is the ratio of PI divided by percent clay. (2) Swell potential is estimated using S=( ) (PI) 2.44,where PI is plasticity index, and S is percent of axial swell under 6.9 kpa pressure (Das, 1990a) --- Not performed (3) Ammonium Acetate Method T RPT 25

23 page 1 of 1 TABLE 3.3 COMPARISON OF 2008 LABORATORY RESULTS WITH RECOMMENDED CLAY PROPERTIES CONSTRUCTION OF CAP KEY SUBCELL 12, AND CLAY CAP SUBCELL 1, 2 3 CLEAN HARBORS LAMBTON FACILITY CORUNNA, ONTARIO Recommended specifications Average measured values Cap Key SC 12 Clay Cap SC 1, 2 & 3 Permeability < 10-7 cm/s 3E-08 cm/s 1.6E-08 cm/s Percentage fines (< No. 200 sieve) > 50 % 83 % 87 % Percentage of clays (<0.002 mm) > 25 % 40 % 41 % Liquid Limit < 36 % 30% 33 % Plasticity Index (PI) 10<PI<25 % 15 % 16 % Percentage gravel < 10 % 1 % 1 % Activity (A) 0.3<A< Cation Exchange Capacity (1) (CEC) (meg/100 g) 6<CEC< Total Carobonate (1) (TC) > 10 % 33 % 30 % (1) Ammonium Acetate Method T Rpt 25