Geotechnical Investigation Report London Street Generating Station Peterborough, Ontario. February 2012

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2 Geotechnical Investigation Report London Street Generating Station Peterborough, Ontario February 2012

3 Project No February 7, 2012 Mr. Kevin McKeown, Generation Project Manager Peterborough Utilities Inc Ashburnham Drive P. O. Box 4125, Station Main Peterborough, Ontario K9J 6Z5 Re: Geotechnical Investigation Report London Street Generating Station, Peterborough, Ontario Dear Mr. McKeown: We are pleased to submit our Geotechnical Investigation Report for the proposed expansion of the London Street Generating Station, in Peterborough, Ontario. A field investigation and laboratory testing program was conducted to assess soil and groundwater conditions at the site, as input to preliminary design considerations for the proposed diversion canal and new generating station plant. The report includes factual data from the field investigations, and preliminary considerations and recommendations for excavations and groundwater seepage control, foundation design, and general earthworks. It is expected that additional geotechnical recommendations would be required for detailed design of the new facilities. We trust that you will find this report to be relatively straightforward and that it meets with your current expectations and requirements. Please contact us if you have any questions. Yours truly, GENIVAR Inc. J. Stephen Ash, P. Eng., P. Geo. Consulting Engineer/Business Unit Leader 294 Rink Street, Suite 103, Peterborough, Ontario K9J 2K2 Telephone: Fax:

4 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario Table of Contents Transmittal Letter Table of Content 1. INTRODUCTION INVESTIGATION PROCEDURES Borehole Program Hydraulic Conductivity of Bedrock SUBSURFACE PROFILE General Physical Setting Geotechnical Investigation Results Topsoil Sand Fill Sandy Gravel Fill Silty Sand Fill Gravel and Sand Fill Glacial Till Bedrock Groundwater GEOTECHNICAL CONSIDERATIONS General Excavations and Dewatering Foundation Bearing Pressure Seismic Site Class Backfill and Compaction Service Trenches Access Road DESIGN REVIEW, INSPECTIONS AND TESTING LIMITATIONS OF REPORT Figures Figure 1 Figure 2 Figure 3 Site Plan Borehole Location Plan Cross Section A-A Appendices Appendix A Appendix B Appendix C Borehole Explanation Forms, Borehole Logs, Particle Size Distribution Analyses (Figures A1 to A4) Core Photographs Slug Test Results GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc i

5 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario 1. Introduction GENIVAR Inc. (GENIVAR) was commissioned by Peterborough Utilities Inc. (PUI, Client) to perform a Geotechnical Investigation for the proposed expansion of the London Street Generating Station (LSGS), located at 51 London Street, in the City of Peterborough, Ontario (Figure 1). It is understood that existing LSGS output will be expanded from 4 MW to 10 MW, and that the expansion will be comprised of three (3) primary components: 1) Construction of a new intake channel in the Otonabee River fore bay, west of the existing intake and turbine building. It is understood that the intake channel is to be approximately 20 m wide and 5 m deep, relative to existing surface grades, and that it will be sloped at an approximate 10 percent grade toward the turbine inlets; 2) Construction of a new tailrace canal, which will originate from the expanded generating station, and extend southerly towards the existing tailrace canal. It is understood that the new tailrace canal will be approximately 150 m long and 13.5 m deep, relative to existing surface grades; and 3) Expansion of the generating station structure to accommodate new and/or additional turbine units. The purpose of the subject Geotechnical Investigation was to assess soil, bedrock and groundwater conditions at the site, provide factual subsurface data for conceptual design of the project, and to discuss general geotechnical issues including excavations, groundwater seepage control and foundation bearing capacity. The report includes site plans and a cross section, as well as borehole logs and test results for the investigation program. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 1-1

6 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario 2. Investigation Procedures 2.1 Borehole Program A borehole investigation was conducted within the proposed extents of the proposed diversion and tailrace canal between the dates December 12, 2011 and January 6, The investigation advanced six (6) boreholes, designated as BH-01 through BH-06, to depths of up to 20 m below the existing ground surface grade. The investigation area and borehole locations are indicated on Figure 2. Four (4) of the holes met refusal on the presumed bedrock surface, at depths of 5.4 m to 9.2 m below ground level, and two of the boreholes (BH-04 and BH-05) were advanced several meters into the bedrock using coring techniques. Drilling and sampling was completed using a track-mounted CME-55 drill rig operating under the supervision of GENIVAR technicians. Within the overburden, the boreholes were advanced to sampling depths by means of continuous flight hollow-stem augers. Standard Penetration Test (SPT) N values were recorded for the sampled intervals as the number of blows required to drive a 50 mm outside diameter (OD) split-spoon sampler 305 mm into the soil, using a 63.5 kg drop hammer falling 750 mm (ASTM D1586 procedure). SPT N values so recorded in this report are used to assess consistency for cohesive soils and relative density for non-cohesive materials. Soil samples for reference and testing were collected at approximately 0.75 m and 1.5 m intervals. The samples were logged in the field using visual and tactile methods, and subsequently were placed into labelled plastic bags for transport, future reference, possible laboratory testing, and temporary storage. Open boreholes were checked for groundwater and general stability prior to backfilling. Bedrock sampling was performed using an NQ (46.5 mm) diameter diamond bit core barrel, with river water pumped to a recirculation tank and used for drilling lubrication. Rock core samples were logged and photographed in the field. Core Run Recovery and Rock Quality Designation (RQD) ratios were measured, and core samples were placed into labelled core boxes for shipment and temporary storage. Three (3) groundwater monitors, consisting of 50 mm outside diameter PVC machine-slotted screen and riser pipe, were installed to measure static groundwater levels at the site. A bi-level nested monitor was installed at BH11-4 (as designated by i for deep and ii for shallow monitor), and a single monitor was installed at BH11-5. The deeper monitors were screened within selected intervals of the fractured bedrock. The shallow monitor BH-04ii was screened within the overburden soil above the bedrock interface. Standpipe annuli were sealed with bentonite pellets or grout, and the above-ground riser pipe sections were fitted with a lockable protective covers embedded in lean concrete. General construction details for the monitors are provided in the appended borehole logs. A relative elevation survey of the borehole locations was conducted by GENIVAR field staff; ground elevations referenced to a topographic datum taken from Ontario Base Mapping for the site. From the survey, the floor slab of the existing generating station building was measured at metres above sea level (masl). Corrections may be required to the relative survey results to establish more precise geodetic elevations for detailed design and construction of the project. Groundwater levels in the monitors were measured upon completion of installation and several days later, on January 10, Findings are discussed later in the report. Field procedures to assess hydraulic conductivity of the bedrock are discussed in Section 2.2 below. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 2-1

7 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario Laboratory testing for the subject investigation included four (4) Particle Size Distribution Analyses (ASTM D422). In addition, eight (8) selected samples of bedrock core were submitted for Point Load Index testing as an indicator of unconfined compressive strength (UCS). Test samples were taken at approximately 3.0 m intervals from boreholes BH11-4 and BH11-5. Laboratory test results are included in the Appendix of this report, and on the borehole logs. 2.2 Hydraulic Conductivity of Bedrock Single well response tests (rising head tests) were conducted in groundwater monitors BH-04i and BH- 05, on January 16, 2012, to assess the bulk hydraulic conductivity (K) of selected bedrock intervals. Prior to completing these tests, the monitors were flushed several times with fresh water and purged to clear fine sediment caused by drilling. The rising head test procedure removes a known volume of water from the monitor casing, and measures the time required for the groundwater level to return to recover to 37 percent of the initial change (i.e. Hvorslev Method). Electronic data loggers were used to record groundwater levels during testing, and three test trials were completed at each monitor to obtain an average K value. Test results are included in Appendix C. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 2-2

8 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario 3. Subsurface Profile 3.1 General Physical Setting The subject LSGS site is located in the Peterborough Drumlin Physiographic Region of Ontario (Chapman and Putnam, 1984), in an area characterized as having rolling plains of drumlinized glacial till overlying calcareous limestone bedrock of the middle Ordovician age Verulam Formation. The ground surface across most of the investigated site is fairly flat, but there are relatively steep slopes along the existing tailrace canal and the Otonabee River main channel, south of the existing generating station. Groundwater and surface water drainage appears to be mainly south-easterly, towards the river, which flows southerly into Little Lake. Existing land development in the site vicinity includes private residential dwellings along London Street, and the Pepsi QTG (formerly Quaker Oats) plant to the south. A gravel access road currently connects the plant to London Street, and passes by the site entrance lane. A railway spur associated with the Pepsi operation crosses the subject lands and the proposed diversion canal alignment. The current site layout is indicated on Figure 1. The bedrock surface is generally about 8.5 m below ground surface in the site area. Bedrock is exposed in the side slopes and bottom of the tailrace canal. It is understood that a previous diversion canal crossed the investigation area prior to the 1900 s, specifically in the area of BH-01. It is suspected that this former canal was backfilled near the time when the existing generating station and dam were constructed, with the backfill material suspected to consist of rock and earth fill, construction debris, and possibly other materials from off-site sources. Coarse rock fill with cobbles and boulders is notable in areas along the canal shoreline and associated slopes. 3.2 Geotechnical Investigation Results The soil profile at the site generally consists of a surficial layer of topsoil overlying variable fill materials ranging from sandy gravel, gravel and sand, and silty sand. The fill materials overlie sandy silt glacial till and limestone bedrock units. Five (5) of the investigation boreholes were terminated within the overburden, at depths ranging from 5.9 m and 9.2 m below ground surface. Two (2) of the boreholes were terminated within bedrock, at depths of 18.8 m and 20.0 m below ground surface. A north to south cross-section of the subsurface profile at the site is included as Figure 3, and borehole logs are included in the Appendix. Descriptions of individual material layers encountered during the investigation are as follows Topsoil A layer of dark brown sandy silt topsoil was penetrated in each of the boreholes, except BH-03. The topsoil is typically about 0.1 m thick, except at BH-06 where it was approximately 0.7 m thick. The topsoil contains occasional roots and organic matter, and was moist at the time of the investigation, with loose relative density on the basis of SPT N values ranging from 4 to 9 (blows per 305 mm penetration) Sand Fill A thin layer of dark brown, moist sand with a trace of silt was encountered beneath the topsoil layer at borehole BH-02. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 3-1

9 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario Sandy Gravel Fill Black sandy gravel fill was encountered in boreholes BH-01, BH-02 and BH-06, and contains a trace of silt and crushed concrete fragments. The sandy gravel varies from 0.5 m thick at BH-01, to 4.1 m thick at BH-02. The material generally has loose relative density on the basis of SPT N values ranging from 4 to 5. An N value of 32 was recorded at BH-06, but was likely due to presence of rock debris. A laboratory particle size distribution analysis was completed on a select sample of the sandy gravel fill taken from BH-06 at 1.5 m to 2.0 m depth. Results are presented in the Appendix (Figure A4), and indicate the following gradations based on the MIT classification system: Gravel (greater than 2 mm size) - 57 % Sand (0.06 mm to 2 mm size) - 33 % Silt (0.02 mm to 0.06 mm size) - 10 % Clay (less than mm size) - 0 % Silty Sand Fill Silty sand fill was encountered in BH-01, BH-04, BH-05 and BH-06, and contains some gravel and traces of silt and organics (specifically wood fragments). The silty sand varies from 0.8 m thick at BH-01, to 3.2 m thick at BH-04, and was encountered at depths of 0.1 m to 2.9 m below ground surface. This fill material has loose to compact relative density on the basis of SPT N values ranging from 6 to 28. A laboratory particle size distribution analysis was completed on a selected sample of the silty sand fill unit taken from BH-04 at depths of 1.5 m to 2.0 m. Results are presented in the Appendix (Figure A2), and indicate the following gradations based on the MIT classification system: Gravel (greater than 2 mm size) - 9 % Sand (0.06 mm to 2 mm size) - 41 % Silt (0.002 mm to 0.06 mm size) - 31 % Clay (less than mm size) - 11 % Gravel and Sand Fill Relatively coarse gravel and sand fill was encountered in all boreholes except BH-03 and BH-04. This material contains some silt and traces of wood fragments, and was wet to saturated at the time of the investigation. The gravel and sand fill layer varies from 0.7 m to 1.5 m thick and was penetrated at depths of 2.9 m to 4.3 m below ground surface. Relative density is loose to compact on the basis of SPT N values ranging from 9 to 20. A laboratory particle size distribution analysis was completed on a selected sample of the gravel and sand fill unit taken from BH-02 from depths of 4.6 m to 5.0 m. Results are presented in the Appendix (Figure A1), and indicate the following gradations based on the MIT classification system: Gravel (greater than 2 mm size) - 48 % Sand (0.06 mm to 2 mm size) - 38 % Silt (0.002 mm to 0.06 mm size) - 14 % Clay (less than mm size) - 0 % Glacial Till All of the boreholes penetrated a deposit of sandy silt glacial till between the fill and the bedrock layers. The till contains a trace of clay and gravel, with occasional cobbles and boulders, ranges from light brown to grey in colour, and is moist to saturated. The till layer is 3.1 m to 5.7 m thick and generally exists at 4 GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 3-2

10 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario m to 5 m below ground level. Based on SPT N values ranging from 10 blows to greater than 50 blows per 305 mm of penetration, the till is compact to very dense, with density generally increasing with depth. A laboratory particle size distribution analysis was completed on a selected sample of the till material taken from BH-04 at 6.1 to 6.6 m depth. Results are presented in the Appendix (Figure A3, and indicate the following gradations based on the MIT classification system: Gravel (greater than 2 mm size) - 18 % Sand (0.06 mm to 2 mm size) - 27 % Silt (0.002 mm to 0.06 mm size) - 40 % Clay (less than mm size) - 15 % Bedrock Boreholes which were not core sampled were terminated upon refusal on the presumed bedrock surface, at depths ranging from 5.9 m to 9.1 m below ground surface. It is inferred that the bedrock surface slopes gently to the south-east, toward Otonabee River. Based on geological descriptions of core samples included in the appended logs, the bedrock consists of grey, horizontally-bedded limestone with interbedded layers of shale and silty clay (Verulam Formation). The rock mass appears to be variably fractured, and slightly weathered; however, several intervals ranging from 0.05 m to 0.35 m long appear to be severely weathered with poorer rock quality. Rock Quality Designations (RQD s) for the bedrock core samples ranged from 17% (very poor) to 68% (fair) within the anticipated excavation limits. A notable improvement in bedrock quality was noted below below 15.5 m depth in BH-04, but RQD was fairly consistent overall in BH-05. The bedrock is classified as medium hard with an estimated unconfined compressive strength (UCS) of 50 MPa to 140 MPa for intact samples, based on axial point load indices. Compressive strength of severely weathered and intensely broken sections of core samples is presumed to be significantly less than this lower limit. Compressive strength of relatively thin shaly interbeds is estimated to range from 1 MPa to 15 MPa, which is considered to be relatively weak compared to the rock mass at large. Photographs of bedrock core samples are included in the Appendix for reference. Results of single-well response tests for the bedrock monitors installed onsite are included in Appendix C, and indicate that bulk hydraulic conductivity ranges from approximately 3 x 10-8 m/s to 5 x 10-7 m/s. Similar results were obtained for packer test results completed at a nearby development along the river, upstream of the site. The test results suggest a fairly low groundwater seepage potential through the bedrock, but it should be appreciated that significant spatial variations in hydraulic conductivity may exist, depending on the characteristics of local discontinuities and other rock mass properties. Seepage assessments for detailed design and construction considerations may require additional investigations, and possibly more sophisticated packer tests or well pumping tests to confirm that the current findings are representative and consistent with expectations Groundwater It is inferred that the shallow groundwater levels at the site are controlled by the adjacent surface water systems. Groundwater appears to exist as perched lenses within shallow overburden materials, and within the denser till soil. Moist to saturated soils were observed within the boreholes at variable depths. It is inferred from site data that the shallow groundwater table within the overburden slopes between the Otonabee River fore bay (elevation masl) and the existing tailrace canal (elevation masl). The head loss is fairly uniform as shown on Figure 3. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 3-3

11 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario The groundwater elevation in the bedrock monitors was approximately 190 masl, which is close to the tailrace channel elevation, and below the groundwater level in the overburden. Thus, it appears that a downward vertical gradient exists at the site, creating a potential for groundwater recharge/infiltration conditions. It is expected that groundwater levels at the site will fluctuate with seasonal weather events, and the controlled surface water levels in the area. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 3-4

12 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario 4. Geotechnical Considerations 4.1 General Geotechnical design considerations related to the construction of the proposed intake and tailrace canals and expansion of the generating station structure are discussed in this section. Recommendations are based on the borehole information, which we believe to be fairly representative of the actual subsurface conditions. It should be appreciated that subsurface conditions may vary between the investigated boreholes, and we should be contacted if significant variations are found so that we may adjust or revise our recommendations, if necessary. It is notable that a backfilled former diversion canal crosses the site and may contain irregular debris (including rock and construction debris), and this factor should be addressed for proposed design and construction. Additional investigations, including trial excavations, may be required to characterize this material. 4.2 Excavations and Dewatering As noted previously, it is understood that LSGS expansion will involve the construction of a new inlet canal, a tailrace canal, and expansion and reconfiguration of the existing generating (turbine) plant and dam. We understand that PUI would prefer to maintain existing generating capacity during construction. As such, consideration should be given to managing groundwater seepage potential at maximum head conditions, in efforts to control stability and overall drainage of the excavations. For the new generating plant structure and upstream intake area, the designer should anticipate the need for a cutoff system, such as a retained earth plug and/or interlocking sheeting, to hold back fore bay and river water heads. Relatively coarse debris and mixed layers of porous granular fill have the capability to conduct significant amounts of water into construction excavations, and even with seepage cutoffs substantial pumping of leakage may be required. As noted, the presence of an old debris-filled canal crossing the site is a concern and configuration of an effective cutoff with excavation pumping system is dependent on the detailed design requirements. If pumping requirements during construction exceed 50,000 L/day, a Permit to Take Water (PTTW) will be required from the MOE. It is likely that the PTTW would be Category 3 due to the expected duration of construction; as such PTTW approval will require acceptance of an impact assessment and water discharge plan that considers existing environmental features. Within the primary construction areas where structural loads are to be applied, it is expected that low quality fill material would be removed to expose competent bearing material, such as dense till soil or sound bedrock. Assuming Type 4 dominating materials, unsupported excavations in the fill zone should not be steeper than 3H:1V, under OHSA regulations (O. Reg. 213/91), unless otherwise approved by the Geotechnical Engineer. Excavation material management may require off-site disposal, and additional physical/chemical assessments of soil quality may be required to comply with provincial waste and landfill regulations. Excavations should be protected from exposure to precipitation and associated ground surface runoff, and should be inspected regularly during construction to address localized instability. The intermediate silty sand glacial till soil is moist to saturated, and is a relatively dense and consolidated soil deposit. The till may contain occasional layers of saturated granular material, however, the relative seepage potential for this material should be fairly low, with bulk hydraulic conductivity expected be less than 10-5 m/s. The till should be considered as a Type 3 material under OHSA regulations, and vertical unsupported cuts up to 1.2 m may be possible, provide groundwater seepage is not a significant factor. Contractors should be prepared to deal with cobbles and boulders within the till unit. Based on an estimated Rock Mass Rating (RMR) of approximately 35 for the horizontally-bedded limestone, it is expected that the majority of the bedrock excavation for the generating plant and diversion canal can be completed with heavy mechanical breakers and rippers. Unsupported near-vertical rock cuts should be reasonably stable within the construction term, with the exception of potential localized spalling GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 4-1

13 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario of fractured material and sloughing of interbedded shaley/silty seams. A small potential exists for localized rock squeeze to develop within thinly bedded rock units, due to construction unloading and remnant horizontal stresses. Therefore, structures embedded within bedrock should be designed to resist or absorb strains from potential rock squeeze. Details should be assessed when more information is available. The bottom of the proposed tailrace canal is to be located within the bedrock, and below the groundwater table/potentiometric surface. Excavations into the bedrock should anticipate seepage from fractures and relatively porous zones. The quantity of seepage will be dependent on the relative pressure head and the bulk hydraulic conductivity of the bedrock. Limited testing for the current investigation indicates that groundwater seepage into the canal during controlled construction operations should be less than 10 L/min, per 10 m linear section. However, additional seepage could occur through the overburden. Based on these findings, and provided cutoffs will be used close to surface water areas, it appears that groundwater could be adequately controlled within the excavations using filtered sumps and pumps. Contractors should confirm dewatering requirements with additional tests and trial pumping, as a basis for tendering, permit approvals and cost management. Also, the designer should confirm canal leakage tolerances, so that this can be assessed with respect to the observed bedrock conditions. We understand that the new intake and tailrace canal will probably be un-lined; GENIVAR should be advised if this is not the case, to provide appropriate geotechnical recommendations for a liner design. For an unlined channel, erosion of the bedrock, and the softer shaly layers in particular, should be anticipated, which may cause localized undermining and spalling of the canal walls and require periodic maintenance. 4.3 Foundation Bearing Pressure We understand that the existing generating station will be enlarged to the west, and reconfigured for the proposed expansion, including installation of new turbines. Details were not available at the time of reporting. The floor slab of the existing plant is situated at relative elevation masl (Figure 3), which should be approximately 2 to 3 metres above the bedrock. We expect that the foundation for the existing structure is situated on the bedrock, but this has not been confirmed. It is anticipated that the new generating station will be founded on the bedrock, close to the bottom grade of the proposed tailrace canal (i.e. approximate elevation 185 masl). Bedrock at this level consists of poor to fair quality fractured and horizontally-bedded limestone with an estimated unconfined compressive strength of 50 MPa (Grade R3 as per CFEM 4 th edition, 2006). Shaly layers are relatively weak (Grade R1) compared to limestone beds. For preliminary design, assuming that weak shale beds are not significant at the design grades a preliminary design bearing pressure (SLS) of 500 kpa may be assumed. If higher loadings are required, additional assessments of the bedrock conditions immediately below the proposed foundation elements should be completed. Field confirmation of the allowable bearing capacity is required by the Geotechnical Engineer during construction. Concrete corrosion and electrical resistivity analyses were not completed within the current scope of work, to assess requirements for concrete mix design and grounding potential. GENIVAR should be contacted if this information is required for conceptual design, and we can advise if additional tests are required. This information should be addressed in detailed design. 4.4 Seismic Site Class The Ontario Building Code specifies that structures should be designed to withstand forces due to earthquakes. For the purpose of earthquake design, the information relevant to the geotechnical conditions at a site is attributed by the Site Class. Based on the explored soil properties and in accordance with Table A of the Building Code (2006), it is recommended that Site Class C (very dense soil and soft rock) be applied for the current design. Analysis of shear waves may be required to justify increases in Site Class designation under the Code. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 4-2

14 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario 4.5 Backfill and Compaction Provided that it is not saturated or otherwise deemed unacceptable, glacial till material within the investigation area could be reused for non-structural backfill in selected project areas. Only clean, imported material (Ontario Provincial Specification 1010) approved by the Geotechnical Engineer should be used for structural fill, including under proposed structures and as backfill. Where required, backfill should be relatively incompressible, stable and free draining. The compaction design standard for structural fill should be 100 percent standard Proctor maximum dry density (SPMDD), as per ASTM D698 procedures, unless otherwise noted and approved by the Geotechnical Engineer. Granular material should be placed at optimum moisture content for compaction, and be compacted in lifts that are less than 300 mm thick (or as appropriate for the size of equipment to be used). 4.6 Service Trenches Excavations for shallow service trenches shall consider the information presented in Section 4.2. Given the onsite fill conditions, Type 4 soil conditions should be assumed and excavations should be backsloped at 3:1, or be supported using engineered systems. Service pipes can be installed with Class B bedding in accordance with OPSD Pipe bedding should be compacted to at least 98 percent of SPMDD. 4.7 Access Road It is assumed that the site will be accessed by gravel access roads, similar to existing conditions. For preliminary design, it should be assumed that light duty road bases consist of at least 150 mm OPSS 1010 Granular A, overlying 300 mm OPSS Granular B (Type 1). Subgrade conditions shall be inspected and approved by the Geotechnical Engineer during construction, for the loadings to be applied. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 4-3

15 Geotechnical Services Report London Street Generating Station, Peterborough, Ontario 5. Design Review, Inspections and Testing Since limited project details were available at the time of report preparation, GENIVAR should be contacted to review and comment on conceptual and preliminary designs and, if necessary, complete additional geotechnical evaluations for detailed design. Geotechnical inspections will be crucial during construction operations to address unexpected conditions, and for quality control and assurance (QA/QC). Inspection and testing services should include verification of subgrade soil and bedrock conditions, inspection/documentation of seepage, monitoring of the placement of engineered fills, and general testing of geotechnical materials including engineered fill, and concrete. GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 5-1

16 Geotechnical Investigation Report London Street Generating Station, Peterborough, Ontario 6. Limitations of Report The data, conclusions and recommendations which are presented in this geotechnical report, and the quality thereof, are based on a scope of work authorized by the Client. While we believe the borehole information to be representative of site conditions, subsurface conditions between and beyond the test hole locations may vary significantly. If significant differences in the subsurface conditions described above are found, we should be contacted immediately to revise our findings and recommendations, as necessary. The design recommendations provided in this report are intended for designers and should not be construed as providing instructions to contractors, who should form their own opinions about site conditions for tending, construction procedures and general planning. GENIVAR accepts no liability for use of or reliance on the report information by third parties, without express written consent. Prepared by: GENIVAR Inc. Arash Yazdani, B.E.Sc., E.I.T., LEED G.A. Project Manager J. Stephen Ash, P. Eng., P. Geo. Consulting Engineer/Business Unit Leader GENIVAR H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Geotechnical Report.doc 6-1

17 Figures Figure 1 Site Plan Figure 2 Borehole Location Plan Figure 3 Cross Section A-A

18 +/- 1 : 2,750

19

20

21 Appendix A Borehole Explanation Forms Borehole Logs Particle Size Distribution Analyses (Figures A1 to A4)

22 BOREHOLE LOG EXPLANATION FORM This explanatory section provides the background to assist in the use of the borehole logs. Each of the headings used on the borehole log, is briefly explained. DEPTH This column gives the depth of interpreted geologic contacts in metres below ground surface. STRATIGRAPHIC DESCRIPTION This column gives a description of the soil based on a tactile examination of the samples and/or laboratory test results. Each stratum is described according to the following classification and terminology. Soil Classification* Terminology Proportion Clay <0.002 mm Silt to 0.06 mm "trace" (e.g. trace sand) <10% Sand 0.06 to 2 mm "some" (e.g. some sand) 10% - 20% Gravel 2 to 60 mm adjective (e.g. sandy) 20% - 35% Cobbles 60 to 200 mm "and" (e.g. and sand) 35% - 50% Boulders >200 mm noun (e.g. sand) >50% * Extension of MIT Classification system unless otherwise noted. The use of the geologic term "till" implies that both disseminated coarser grained (sand, gravel, cobbles or boulders) particles and finer grained (silt and clay) particles may occur within the described matrix. The compactness of cohesionless soils and the consistency of cohesive soils are defined by the following: COHESIONLESS SOIL COHESIVE SOIL Standard Penetration Standard Penetration Compactness Resistance "N", Consistency Resistance "N", Blows / 0.3 m Blows / 0.3 m Very Loose 0 to 4 Very Soft 0 to 2 Loose 4 to 10 Soft 2 to 4 Compact 10 to 30 Firm 4 to 8 Dense 30 to 50 Stiff 8 to 15 Very Dense Over 50 Very Stiff 15 to 30 Hard Over 30 The moisture conditions of cohesionless and cohesive soils are defined as follows. COHESIONLESS SOILS COHESIVE SOILS Dry DTPL - Drier Than Plastic Limit Moist APL - About Plastic Limit Wet WTPL - Wetter Than Plastic Limit Saturated MWTPL - Much Wetter Than Plastic Limit 17/03/09 4:41 PM Admin/Borehole Log Explanation Form

23 STRATIGRAPHY Symbols may be used to pictorially identify the interpreted stratigraphy of the soil and rock strata. MONITOR DETAILS This column shows the position and designation of standpipe and/or piezometer ground water monitors installed in the borehole. Also the water level may be shown for the date indicated. Where monitors are placed in separate boreholes, these are shown individually in the "Monitor Details" column. Otherwise, monitors are in the same borehole. For further data regarding seals, screens, etc., the reader is referred to the summary of monitor details table. SAMPLE These columns describe the sample type and number, the "N" value, the water content, the percentage recovery, and Rock Quality Designation (RQD), of each sample obtained from the borehole where applicable. The information is recorded at the approximate depth at which the sample was obtained. The legend for sample type is explained below. SS = Split Spoon GS = Grab Sample ST = Thin Walled Shelby Tube CS = Channel Sample AS = Auger Flight Sample WS = Wash Sample CC = Continuous Core RC = Rock Core % Recovery = Length of Core Recovered Per Run x 100 Total Length of Run Where rock drilling was carried out, the term RQD (Rock Quality Designation) is used. The RQD is an indirect measure of the number of fractures and soundness of the rock mass. It is obtained from the rock cores by summing the length of core recovered, counting only those pieces of sound core that are 100 mm or more in length. The RQD value is expressed as a percentage and is the ratio of the summed core lengths to the total length of core run. The classification based on the RQD value is given below. 17/03/09 4:41 PM Admin/Borehole Log Explanation Form

24 RQD Classification RQD (%) Very poor quality < 25 Poor quality Fair quality Good quality Excellent quality TEST DATA The central section of the log provides graphs which are used to plot selected field and laboratory test results at the depth at which they were carried out. The plotting scales are shown at the head of the column. Dynamic Penetration Resistance - The number of blows required to advance a 51 mm diameter, 60º steel cone fitted to the end of 45 mm OD drill rods, 0.3 m into the subsoil. The cone is driven with a 63.5 kg hammer over a fall of 750 mm. Standard Penetration Resistance - Standard Penetration Test (SPT) "N" Value - The number of blows required to advance a 51 mm diameter standard split-spoon sampler 300 mm into the subsoil, driven by means of a 63.5 kg hammer falling freely a distance of 750 mm. In cases where the split spoon does not penetrate 300 mm, the number of blows over the distance of actual penetration in millimetres is shown as xblows mm Water Content - W P - W L - The ratio of the mass of water to the mass of oven-dry solids in the soil expressed as a percentage. Plastic Limit of a fine-grained soil expressed as a percentage as determined from the Atterberg Limit Test. Liquid Limit of a fine-grained soil expressed as a percentage as determined from the Atterberg Limit Test. REMARKS The last column describes pertinent drilling details, field observations and/or provides an indication of other field or laboratory tests that were performed. 17/03/09 4:41 PM Admin/Borehole Log Explanation Form

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34 PARTICLE SIZE DISTRIBUTION HYDROMETER STANDARD SIEVE SIZES /4" 3/8" 1/2" 3/4" 1" 1½" 2" 3" CUMULATIVE PERCENT PASSING MIT Classification System GRAIN SIZE IN MILLIMETRES CLAY SILT SAND GRAVEL Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse COBBLES Project Name: London Street Generating Station Project No.: Figure No.: A1 Location ID.: BH02 Sample No./Depth: SS6 / m Remarks: Gravel and sand, some silt

35 PARTICLE SIZE DISTRIBUTION HYDROMETER STANDARD SIEVE SIZES /8" 1/2" 3/4" 1" 4 1½" 2" "4 3" CUMULATIVE PERCENT PASSING GRAIN SIZE IN MILLIMETRES MIT Classification System CLAY Fine SILT Medium Coarse Fine SAND Medium Coarse Fine GRAVEL Medium Coarse COBBLES Project Name: London Street Project No.: Location ID.: BH-04 Sample No./Depth: S3 ( m) Remarks: Silty sand, some clay, trace gravel Figure No.: A2

36 PARTICLE SIZE DISTRIBUTION HYDROMETER STANDARD SIEVE SIZES /4" 3/8" 1/2" 3/4" 1" 1½" 2" 3" CUMULATIVE PERCENT PASSING MIT Classification System GRAIN SIZE IN MILLIMETRES CLAY SILT SAND GRAVEL Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse COBBLES Project Name: London Street Generating Station Project No.: Location ID.: BH04 Sample No./Depth: SS7 / m Remarks: Sandy silt, some gravel, some clay Figure No.: A3

37 PARTICLE SIZE DISTRIBUTION HYDROMETER STANDARD SIEVE SIZES /4" 3/8" 1/2" 3/4" 1" 1½" 2" 3" CUMULATIVE PERCENT PASSING MIT Classification System GRAIN SIZE IN MILLIMETRES CLAY SILT SAND GRAVEL Fine Medium Coarse Fine Medium Coarse Fine Medium Coarse COBBLES Project Name: London Street Project No.: Figure No.: A4 Location ID.: BH06 Sample No./Depth: SS3 ( m) Remarks: Sandy gravel, trace silt

38 Appendix B Core Photographs

39 Geotechnical Investigation Report London Street Generating Station, Peterborough, Ontario Photograph 1: BH-04. Bedrock core from 8.7 m to 20 m depth below surface.

40 Geotechnical Investigation Report London Street Generating Station, Peterborough, Ontario Photograph 2: BH-05. Bedrock core from 9.1 m to 18.7 m depth (core runs out of order in photograph).

41 Appendix C Slug Test Results

42 STATIC WATER LEVEL (ho) BOREHOLE RADIUS ( R ) SAND SCREEN LENGTH (L) MONITOR RADIUS ( r ) PIPE SCREEN LENGTH Time (T 0 ) Hydraulic Conductivity (K) Note m 4.8 cm cm 2.54 cm cm 13 min 4.90E-07 m/s Change in Water Elapsed Time (min) Depth to Water (m) h/ho Level, h (m) Note 1: Formula used to calculate hydraulic conductivity: K = r 2 ln (L/R) 2 LT 0

43 Static Water Level : 8.78 mbtop Project Name : London Street Generating Station, Peterborough Well Depth: mbtop Project No : Date: 16-Jan-12 mbtop - metres below top of pipe h/ho - change in head/initial change in head FIGURE C-1: SEMI-LOG PLOT HYDRAULIC CONDUCTIVITY TEST GROUNDWATER MONITOR MW h/ho 0.1 Recovery 37% Recovery To ELAPSED TIME (minutes) H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Slug Tests xls 1/26/2012

44 STATIC WATER LEVEL (ho) BOREHOLE RADIUS ( R ) SAND SCREEN LENGTH (L) MONITOR RADIUS ( r ) PIPE SCREEN LENGTH Time (T 0 ) Hydraulic Conductivity (K) Note m 4.8 cm cm 2.54 cm cm 125 min 3.04E-08 m/s Change in Water Level, Elapsed Time (min) Depth to Water (m) h/ho h (m) Note 1: Formula used to calculate hydraulic conductivity: K = r 2 ln (L/R) 2 LT 0

45 Static Water Level : 8.72 mbtop Project Name : London Street Generating Station, Peterborough Well Depth: mbtop Project No : Date: 16-Jan-12 mbtop - metres below top of pipe h/ho - change in head/initial change in head FIGURE C-2: SEMI-LOG PLOT HYDRAULIC CONDUCTIVITY TEST GROUNDWATER MONITOR MW04-i 1.0 h/ho % Recovery Recovery To ELAPSED TIME (minutes) H:\Proj\GENIVAR 2011\ London St Gen Station\Tech\Slug Tests xls 1/26/2012