report on geotechnical investigation duffin creek …

REPORT ON GEOTECHNICAL INVESTIGATION DUFFIN CREEK WPCP OUTFALL VOLUME 2 INTERPRETATION AND DESIGN RECOMMENDATIONS The Regional Municipality of Durham Works Department 605 Rossland Road East, Level 5 PO Box 623 Whitby, ON L1N 6A3 GEOTMARK00171AA June, 2012

Distribution 4 copies CH2M HILL, Daniel Olsen P.Eng. 1 copy Coffey Geotechnics

CONTENTS

Coffey Geotechnics GEOTMARK00171AA June, 2012

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REPORT ON GEOTECHNICAL INVESTIGATION 1

1 INTRODUCTION 1

1.1 Project Background, Overview 2

1.2 Description of Site and Regional Geology 2

1.3 Summarized Subsurface Conditions 3

1.4 Proposed Design Alternatives 4

1.5 Tunnel Alternative 4

1.5.1 Recommended Alignment 4

1.5.2 Anticipated Rock Conditions in the Zone of Tunneling 5

1.5.3 Tunneling Method 6

1.5.4 Temporary Tunnel Support 6

1.5.5 Groundwater Infiltration into the Tunnel 7

1.5.6 Gas 8

1.5.7 In Situ Stresses 8

1.5.8 Time-Dependent Deformation Characteristics (TDD) 8

1.5.9 Design of Permanent Tunnel Liner 9

1.5.10 Seismicity and Ground Motion Estimates 10

1.6 Precast Concrete Pipe Laying Alternative 11

1.6.1 Excavation 11

1.6.2 Pipe Support 12

1.7 Statement of Limitations 12

List of References

Appendices

Appendix A: Drawings (1-13)

Appendix B: Figures, Tables

Appendix C: Statement of Limitation

Report on Geotechnical Investigation Duffin Creek Water Pollution Control Plant Outfall - Volume 2


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REPORT ON GEOTECHNICAL INVESTIGATION

DUFFIN CREEK WATER POLLUTION CONTROL PLANT OUTFALL

THE REGIONAL MUNICIPALITY OF DURHAM

1 INTRODUCTION

Coffey Geotechnics Inc. (Coffey) was retained by the Regional Municipalities of Durham and York (the Regions) to carry out a geotechnical investigation and to prepare a geotechnical report for a new potential Duffin Creek Water Pollution Control Plant (WPCP) Outfall.

The purpose of the geotechnical investigation is to characterize the lake bottom soil and bedrock conditions and to provide geotechnical input for the environmental assessment (EA) and preliminary design stages of the outfall. Investigation of the land portion of the project (e.g. potential shaft) was not part of the assignment. During the detail design stage of the project it is proposed that a borehole or boreholes be drilled on land and at the shaft location

The results of the off-shore investigation are presented in a report consisting of two volumes. In Volume 1, the factual information generated by the investigation is presented. In Volume 2, the factual data is interpreted as relevant to the geotechnical design and construction of the project.

It is brought to the reader’s attention that the reported soil and rock conditions are known only at the relatively widely spaced (250 m to 500 m) borehole locations and that variations in the properties of the deposits can be expected between the boreholes.



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VOLUME 2

INTERPRETATION AND DESIGN RECOMMENDATIONS

1.1 Project Background, Overview

The Duffin Creek WPCP is located at 901 McKay Road in the City of Pickering. The WPCP is jointly owned by the Regions of Durham and York and is operated by Durham. To meet the growing demand, the Regions plan to increase the present 420 MLD process capacity of the plant to 630 MLD. Since this expansion of the process capacity exceeds the 560 MLD hydraulic capacity of the existing outfall, the construction of a new outfall pipe may become necessary.

The Schedule C Class Environmental Assessment (EA) currently being undertaken by CH2M Hill Canada Limited (CH2M) tentatively concluded that the new outfall should be a 3600 mm I.D. pipe reaching into the lake a maximum distance of 3000 m. The investigation described in this report is in support of the Class EA.

The potential Duffin Creek WPCP Outfall would be located on the shoreline of Lake Ontario, from where the outfall pipe would extend perpendicularly to a maximum distance of 3000 m into Lake Ontario. The new outfall alignment would be roughly parallel to the existing outfall and would be about 200 m to 300 m to the east of it.

The purpose of the present investigation is to characterize the geotechnical conditions for the offshore portion of the outfall between the shoreline and the proposed diffuser, to be located a maximum of 3000 m offshore, where the water depth exceeds 20 m. Presently, two options for construction are being considered: a deep concrete lined rock tunnel or a concrete pipe placed in a dredged or excavated trench at lake bottom.

1.2 Description of Site and Regional Geology

The project site is located in Lake Ontario, on the shore of which the Duffin Creek WPCP is located. Immediately to the west is the Pickering Nuclear Generating Station, while to the east is the estuary of the Duffin Creek. Further along the shoreline, both to the west and to the east are park lands beyond which are residential subdivisions.

The City of Pickering is located in the physiographical region of the Iroquois Plain along the north shore of Lake Ontario, and is bordered in the north by the south slope of the Oak Ridges Moraine. The abandoned old shoreline of post glacial Lake Iroquois, formed as the last glaciers withdrew from the region about 10,000 years ago, lies about 10 km inland from the present Lake Ontario shoreline. The wave-washed Iroquois Plain is characterized by gently rolling, bevelled till plains with flat sand and clay plain areas that formed as lake bed deposits in Lake Iroquois. Deeply eroded stream valleys of the Rouge River and Duffin Creek provide the largest relief in the region.



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Upper Ordovician sedimentary rocks of the Whitby and Lindsay Formations underlie the region. The Whitby formation is grey and black shale and the older Lindsay formation is a grey limestone with thin shale interbeds.

Shales of the Whitby Formation are generally medium strong, moderately fissile, and are of medium durability; they are thinly bedded with two sets of nearly vertical joints. The rock comprises three members of which the lowest (oldest) often contains organic gases.[7]

The limestone of the Lindsay Formation is fine grained, fossiliferous, and massively bedded with thin shale interbeds throughout.[9]

The inferred bedrock topography, which was plotted from available well drilling data on land, is shown on the attached Drawing 2. As shown on the drawing, the rock surface topography is complex. In addition to a general trend of the rock surface sloping from the north west to the south east the rock is deeply incised with depressions and buried valleys carved out by the glaciers. Two of these valleys, one to the west, the other to the east of the WPCP site, are shown on Drawing 2.

Based on the records of the 1974 Peto McCallum geotechnical investigation one of these rock valleys, possibly the one to the east appears to extend into Lake Ontario and intersect the line of the existing and proposed outfall alignments. Because of the known presence of buried valleys in the bedrock, Coffey retained the ASI Group to perform a geophysical seismic profiling of the lake bottom in order to locate the extent and depth of these buried offshore rock valleys. The results of this survey are presented in Appendix G of Volume 1 of this report. Consideration will be given to undertake an additional geophysical survey as suggested if the new or extended outfall is adopted as the preferred method.

1.3 Summarized Subsurface Conditions

Both, the geotechnical investigation and the geophysical survey established that throughout a significant length of the proposed outfall pipe alignment the surface of the bedrock is overlain by overburden soil deposits. The thickness of these at the borehole locations ranges between 0.1 m and 8.4 m, except at the locations of the buried rock valleys where overburden thicknesses of 14 m to 16 m were recorded. The composition of the overburden soils is highly variable and ranges from very loose or very soft organic silts or clays to very dense glacial tills.

The surface of the bedrock was encountered between Elevations 58.6 m and 40.1 m and its quality was explored by core drilling to between Elevations 21 m and 16 m, i.e. to a depth of 21 m to 39 m below rock surface. To these depths, two rock formations were identified: the upper Whitby Shale and the lower and older Lindsay Limestone Formations.

The Upper Ordovician Whitby Formation is known to consist of the upper, middle and lower (Collingwood) members. The upper and middle members are greenish to brownish, grey fissile shale, while the lower Collingwood member is a dark brownish grey, often highly fossiliferous marl with black shale interbeds and is the most organic rich of the three members. While pockets of gas can be found in all three members, they are more common in the Collingwood member.[7]



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The grey limestone of the Lindsay Formation is typically fine grained, fossiliferous and massively bedded with thin shale interbeds. Two major joint sets, located perpendicularly to each other, are known to exist in this formation. Joint spacing in one of them is close, less than 1 m, but is wider, 1 m to 5 m, in the other.[9]

Inferred subsurface profiles along three sections (A-A, B-B, C-C) drawn through a group of boreholes are presented on Drawing 3 in Appendix A. For more details of the sub-lake bottom conditions encountered at the borehole locations, reference should be made to the individual borehole log sheets and bedrock core log sheets presented in Appendix B of Volume 1.

1.4 Proposed Design Alternatives

For the purpose of the Class EA study, two alternative construction methods for installing the 3.6 m I.D. outfall pipe are proposed: Tunneling and pipe laying in a dredged or excavated trench.

For the tunnel alternative, the preliminary design suggested a tunnel invert elevation of 35 m at the shaft on shore. From here, the tunnel invert would rise at 0.1% to the south to an invert elevation of 38 m at a maximum distance of 3000 m off shore. The nominal diameter of the excavated tunnel is 4.2 m. The proposed 0.1% gradient should be achievable with the present Tunnel Boring Machine (TBM) technology

The depth of the installation in a dredged / excavated trench would be about 5 m to 6 m below the lake bottom in order to provide a minimum of 1 m to 2 m protective soil cover over the top of the pipe.

1.5 Tunnel Alternative

1.5.1 Recommended Alignment

When tunneling in rock, it is considered to be good practice to have an adequate thickness of competent rock cover above the tunnel obvert. This is increasingly more important where a tunnel is to be located below a body of water, Lake Ontario in the present case. For the proposed outfall pipe, we recommend that the rock cover be a minimum of 12 m which is equal to three (3) tunnel diameters (assuming a 4 m diameter bore). To provide this cover, the controlling location, based on the available borehole and geophysical survey data, is the location of Borehole 206 where the rock surface is at its lowest point at about Elevation 40 m. The suggested obvert and invert elevations for the tunnel at the location of Borehole 206 are therefore: Elevations 28 m and 24 m respectively. Maintaining a 0.1% gradient, the tunnel invert at the launching shaft on shore should, therefore, be at about Elevation 21.5 + m. The suggested tunnel alignment is shown on the attached Drawing 3.

The uphill drive on the slight 0.1% gradient, as shown on the preliminary drawings, is conventional in order to drain the tunnel by gravity of groundwater seepage. The disadvantage of the uphill drive in the present case is the increased difficulty of ventilation at the terminal end of the tunnel, since there will be a tendency for gas to migrate upgradient to the terminal end of the tunnel rather than towards the shaft. This will have to be given consideration in the design of the ventilation system.



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1.5.2 Anticipated Rock Conditions in the Zone of Tunneling

Presented on the attached Drawings 4 to 12 are, in the form of histograms, the measured Rock Quality Designation (RQD); Rock Mass Rating (RMR) and the hydraulic conductivity (permeability) values along the three sections. Also shown on Section A-A, drawn through Boreholes 202 to 207 (Drawings 4, 5 and 6), is the suggested vertical alignment of the tunnel. Reference to Drawing 4 indicates that within the suggested zone of the tunnel and to at least one tunnel diameter above the tunnel obvert level the RQD values indicate good to excellent rock conditions. Exception to this was found in Borehole 206A, where within the generally good to excellent rock “fair quality” rock zones also exist.

The RQD values (Drawing 4) within the zone of the tunnel range from 85% to 100% with an average value of 96%. Based on Deere’s classification, these values indicate a rock of good to excellent, but generally excellent quality. Similar good quality rock is found above the tunnel obvert to at least one tunnel diameter, but in the majority of the cases even beyond. As mentioned before somewhat poorer quality rock was found in Borehole 206A, where an average RQD value of 75.5 suggests a fair to good quality rock at this location.

Another measure of rock quality, as relevant to tunneling and mining, is the rock mass rating (RMR). This geomechanics classification was developed by Bieniawski in 1973 and utilizes the following six parameters, most of which are measurable in the field and can also be obtained from borehole data:

Compressive strength (UCS) of the intact rock;

RQD;

Spacing of discontinuities;

Condition of discontinuities (e.g. roughness);

Groundwater conditions;

Orientation of discontinuities.

Each of these parameters is given a rating and the sum of the six ratings is the RMR. Based on the RMR rating, the rocks are classified into five (5) categories ranging from very poor to very good rocks. Since in the present case some of the parameters (spacing and orientation of discontinuities) could not be accurately established, these were conservatively assessed. The calculated RMR values are tabulated in Table D6 and for Section A-A are presented in profile on Drawing 5. As shown, within the zone of the tunnel the RMR ratings range from 49 to 67, with an average value of 60. Based on these, the rock is classified as fair to good rock. Based on the RMR classification system, the quality of the rock above the tunnel obverts can be classified as poor to good, but generally fair (RMR= 28 to 67, average 53).

The bulk hydraulic conductivity or permeability (k) values of the rock mass were measured in situ and are summarized for Section A-A on the profile presented on Drawing 6. The in situ measurements performed in the field within the zone of tunneling gave hydraulic conductivity values ranging from 10-5 to < 10-8 cm/s. Similar or lower permeability values were measured above the tunnel obvert. These values suggest a low to moderate rate of groundwater infiltration into the tunnel opening.



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1.5.3 Tunneling Method

While the method of excavation and the choice of equipment is the responsibility of the contractor, subject to the approval of the Engineer, it is believed that when considering the diameter (4 m+), the maximum length (>2800 m) and the type of the rock, the contractors would most likely opt for tunneling with a tunnel boring machine (TBM) of the gripper type, hard-rock variety, fitted with disc cutters. For a gripper style hard rock TBM and trailing gear, a 100 m radius or greater should be readily achievable on the horizontal curves. Tighter radii are also possible, but at some point it would be necessary to break the trailing gear from the TBM to achieve the curve. The 0.1% incline is not expected to be an operational problem. Locomotive traction issues and the need for sanding to improve traction are typically not a concern until 3% to 4% gradients are encountered

TBM design and cutter head type should, among other things, give consideration to: a) the layered nature of the Lindsay Rock Formation, with layer hardness ranging from 2.5 to 5 on Moh’s hardness scale, b) the abrasive nature of the rock; c) the variability and the difference in UCS values that were observed between the weak ‘interbeds’ and the rest of the rock mass which differences could be in excess of 150 MPa and d) the presence of gas in the bedrock. The TBM design should also give consideration to “rock squeeze” as relevant to the removal of the machine at the end of the excavation.

The contractors may suggest alternative methods of tunneling such as (i) drill and blast, or (ii) excavation with a road header.

Because of the gassy nature of the rock and the potential risk of encountering minimal rock cover coinciding with a zone of very poor quality rock Coffey is not in favour of the drill and blast method of excavation. The drill and blast method may also be unacceptable from the environmental point of view.

Excavation with a road header would be an acceptable method however it would likely require that the diameter of the excavated tunnel be increased. Any advantage of this possibly more economical excavation method would likely be offset by the increased cost of the larger permanent liner.

1.5.4 Temporary Tunnel Support

The choice of temporary ground support measures are also the responsibility of the tunneling contractor, subject to the approval of the Engineer. In addition to providing adequate temporary support to the rock, the design must also take into consideration the clearances required in order to retract the TBM from the tunnel on completion of mining prior to construction of the permanent lining.

Temporary rock support in tunnels in the Toronto area in the less competent Georgian Bay Formation has traditionally taken the form of full steel ribs and timber lagging, or partial ribs and lagging spanning only the crown, supported by rock bolts. Because of the more competent nature of the Lindsay Formation, it is unlikely that full ribs and timber lagging will be needed on this project. For example, during the construction of the water intake tunnel for the Darlington Power Generating Station for the support of the 8 m roof span, in the Lindsay Formation pattern rock bolts with wire mesh were used. The resin grouted 3 m long rock bolts were installed at 1.8 m spacing[9].

Based on the RMR values obtained, we are of the opinion that as a minimum the rock support should consist of 2 m long rock bolts placed at the obvert between the 10 and 2 o’clock positions at 1.5 m to 2 m



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spacing. For safety and the protection of the workers against minor rock falls, wire mesh should be used. The support system should be installed close to, but not more than 10 m behind the face of the excavation. Increased rock support (e.g. longer bolts at closer spacing) will be needed where the rock quality above the tunnel obvert is poor (e.g. Boreholes 206A, 302, 402 and 403).

The temporary lining must allow for free drainage of groundwater seepage through fractures and bedding planes in the rock. This is particularly important in the event that shotcrete is used in lieu of wire mesh. In the event that shotcrete is used the contractor should submit a site specific design stating the type, mix design, reinforcement, thickness and in particular how the water seepage will be controlled.

The temporary tunnel lining system must be designed to accommodate and protect tunneling personnel from: (i) stress induced instability (often referred to as ‘slabbing’ and ‘coning’) due to yielding in the rock surrounding the tunnel given the high in-situ horizontal / vertical stress ratio; (ii) structurally controlled instability given the sub-horizontal bedding plane partings and sub vertical fracture sets in the rock mass releasing blocks or wedges of rock; and (iii) control of physical rock deterioration by ‘slaking’ or desiccation-deterioration.

1.5.5 Groundwater Infiltration into the Tunnel

On the basis of the borehole hydraulic conductivity testing (packer tests) performed, the secondary hydraulic conductivity of the undisturbed rock mass in the potential tunnel horizon in the Lindsay Formation ranges from <<10-6 to 10-5 cm/s, which is relatively low. Test results are presented in Table D5 in Volume 1 and are plotted on Drawing 6 in Appendix A of this report. Significantly higher permeability values can be expected in the shear zones that are known to be present in the formation (e.g. Borehole 302). As a result, these zones, as well as major joints that may be intercepted by the tunnel, will likely contribute to more seepage into the tunnel than will the bulk of the rock mass. To safeguard against unexpected heavy water inflows from shear zones, it is recommended that probe holes be drilled ahead of the face so that these zones can be grouted and the heavy inflows prevented.

A crude approximation of seepage rates into the tunnel can be made using a widely used analytical method developed by Goodman et al (1964). Using the upper range of the measured secondary permeability of 10-5 cm/s for the Lindsay Formation and assuming kv = kh, theoretical seepage rates into the tunnel in the area where competent rock cover is the minimum (e.g. Borehole 206), are expected to be in the order of 0.7 L / minute per metre length of tunnel. With the exception of shear zones where inflow rates could be 100 times that value, the actual average rate of inflow into the tunnel is expected to be much (possibly an order of magnitude) less than the above calculated seepage value. Experience with the Darlington Water Intake Tunnel construction seems to support this opinion.

These flow estimates are, of course, theoretical. The contract should be carefully structured to deal with flow rates of increasing quantity as well as inflow mitigation measures such as localized grouting. For example, a base price might be tendered for an estimated base flow rate, with incremental pricing for higher flow rates requiring higher capacity pumps, generators, etc.

The tunnel floor should be designed to accommodate and convey seepage to a filtered sump at the shaft. Pumped tunnel water is expected to be laden with suspended rock flour and will likely require clarification



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and quality testing before discharging to the water course or the storm water sewer. The need for frequent cleaning of rock flour ‘slimes’ from the drainage channel and sump should be expected.

As previously mentioned, all temporary tunnel lining systems, especially shotcrete, need to have provision to drain seepage water to prevent the build-up of hydrostatic pressures behind the lining. The permanent tunnel liner, however, must be designed to accommodate the full hydrostatic pressure (Lake Ontario level).

1.5.6 Gas

Both the Whitby and Lindsay Formations are known to contain pockets of combustible gas.[7] [9] During the present investigation, pockets of gas were recorded on a single occasion in Boreholes 202 and 204, and on multiple occasions in the other boreholes. Only in Borehole 203 was gas not detected. On most occasions the gas dissipated within 10 minutes to 120 minutes. Considerable quantities of gas under high pressure were recorded in Boreholes 205, 206A, 207, 301 and 302. The dissipation of the gas at these locations took a long time, often overnight. The locations where gas was observed, the type and characteristics of the gas and the time required for dissipation are given in Table D7 in Appendix B.

Ventilation and the monitoring of the gas during all underground work shall be a strict requirement and should be in full compliance with OHSA. The design of the TBM also should be suitable to operate in potentially gassy environment. It is expected that delays will be experienced in waiting for gas to dissipate. The design and installation, as well as the removal of temporary ventilation systems will have to take this into consideration. Difficulties and restrictions due to the presence of gas can also be expected for the drilling and the installation of the diffuser ports.

1.5.7 In Situ Stresses

In-situ stress measurements were not performed as adequate and applicable information on the in-situ rock stresses in the Whitby and Lindsay Formations are available from previous work performed in connection with the design and construction of the Darlington Power Generating Station (PGS) located about 22 km to the east [9]. The values obtained at the PGS site are believed to be applicable to this site as well. At the Darlington Station, the measured major principal stress values in the horizontal direction ranged from 9 MPa to 11 MPa in the Whitby Formation, and between 10 MPa and 14 MPa in the Lindsay Formation. The minor principal stress values were between 4 MPa and 6 MPa in the Whitby Formation and between 6 MPa and 9 MPa in the Lindsay Formation. The orientation of the major horizontal principal stress is N70ºE. [9]

As a result, stress concentrations and overstressing of the rock can be expected at the obvert and invert levels of the tunnel causing instability due to the yielding in the rock and the breaking out of slabs (“slabbing”) and conical shaped rock pieces (‘coning’). For safety reasons, the temporary rock support system should prevent this.

1.5.8 Time-Dependent Deformation Characteristics (TDD)

The Lindsay Formation, similarly to the other Paleozoic sedimentary rock formations found in Southern Ontario, is known to exhibit long term, time dependent deformation characteristics (TDD) also referred to as “rock swelling” or “rock squeezing” [4] [6] [8] An approximate indication of the swelling potential of the rock can be obtained in the laboratory from “free swell tests”. Tests performed on the Lindsay Formation in



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connection with the Darlington PGS indicated a horizontal swelling potential, defined as the expansion strain per log cycle of time, varying from negligible to 0.1% but typically 0.05%[9]. This range was believed to be due to natural variations in the rock formation. The low values were associated with core samples consisting predominantly of limestone with no shale, while the higher values were obtained on samples containing larger amounts of shale interbeds. Field measurements of the horizontal rock convergence during construction confirmed a maximum value of 0.037% of tunnel diameter per log cycle of time [9].

Experience indicates that if the rigid concrete permanent lining is placed against the rock shortly after excavation the lining is cracked due to the “rock squeeze”. In designing for rock squeeze problems, usually two alternatives are considered.

i. After making the excavation, a sufficient length of time is allowed to elapse before the permanent lining is placed, thus allowing the TDD to dissipate as much as possible. Experience indicates that a waiting period of 90 days to 120 days is usually sufficient.

ii. A crushable material can be placed between the rock surface and the liner, so that the applied stresses on the liner are limited to the crushing strength of the protective material placed.

As the magnitude of the TDD cannot be accurately determined in advance, the rate of the rock convergence into the tunnel opening must be monitored during construction in order to determine which of the above two design alternatives should be considered.

We recommend that rock convergence monitoring stations be established at three locations. The layout of the convergence points is shown on Drawing 13 in Appendix A of this report. The convergence points should be installed as soon as the TBM and the trailing gear has passed the location of the monitoring station and readings should be taken as soon as the grout has set. Readings should be taken at frequent time intervals so that a reasonable relationship of deformation versus logarithm of time can be established.

Suggested locations for the monitoring stations are at distances of 100 m, 400 m and 750 m (at the location of Borehole 202) from the launching shaft. Depending on the rate of the advance of the tunnel, these locations may have to be revised or additional locations established in order to provide sufficient time for the monitoring.

The TDD (“rock squeeze”) should also be given consideration in the selection of the excavated diameter of the tunnel and the TBM design, in order to assure the removal (walking out) of the TBM at the completion of the drive.

1.5.9 Design of Permanent Tunnel Liner

In recognition and anticipation that the shale surrounding the tunnel has time-dependent deformation properties and will “squeeze” into the tunnel opening, it is recommended that the permanent liner be installed after a minimum delay-time of three to four months following excavation. The actual delay time must be verified in-situ by means of convergence monitoring at a series of tunnel cross sections as recommended in Section 1.5.8 of this report.

The external pressures acting on the concrete liner at the end of the 90 day delay-time can be taken approximately as follows:



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Pv= vertical rock pressure = 0.260 MPa = (pressure of approximately 10 m of rock cover);

Ph= horizontal pressure = 2.0 MPa;

Pw= hydrostatic water pressure = 0.5 MPa = about 50 m of water head below lake level.

The magnitude of the stress build-up on the tunnel liner will depend on the elastic and time-dependent properties of the rock and the liner, the magnitude of the in-situ stresses in the rock mass, the stiffness of the liner, and the time lag between the excavation and the installation of the permanent liner. Lo and Yuen (1981) proposed a design method which takes into account the rock-structure interaction and which provides solutions for calculating the stresses in the tunnel liner at various time intervals after their installation. The delay time has a significant effect on the magnitudes of the normal and tangential pressures on the tunnel, as well as the maximum compressive and tensile stresses induced in the liner.

If the 90 day delay time cannot be accommodated and the permanent liner has to be placed earlier, or if the calculated external rock pressures overstress the concrete in compression or tension, then it is recommended that a gap be left between the rock face and the permanent liner and the gap be filled with a deformable, crushable material (e.g. polyurethane foam). The modulus and thickness of the foam needs to be determined and based on the predicted remaining convergence of the rock.

In the event that the permanent concrete liner is placed prior to the backing out of the TBM, then the design of the machine should allow for its disassembling.

1.5.10 Diffusers.

The diffusers will be located in an area where the overburden cover above the rock surface is not existing or is shallow (<1 m) although occasionally (e.g. BH403) it could be in excess of 3 m. The vertical shafts of the diffusers can be drilled from a drilling platform. The drilling could be performed either prior to the tunnel excavation or after. A casing through the overburden soils, where present, will be required.

1.5.11 Seismicity and Ground Motion Estimates

Reference should be made to the 2005 National Building Code for the selection of seismic design parameters for this project.

As part of Coffey’s (then Geo-Canada) involvement in the Region of York Long Term Water Project (LTWP) via Durham, Gail M. Atkinson, PhD, Professor at the Ottawa University was retained to evaluate the seismic hazards for the Pickering area. Professor Atkinson also prepared the seismic hazard evaluation upgrades between 1990 and 1998 for the Pickering Nuclear Power Plant. Without providing the details of this unpublished report, Professor Atkinson has reached the following conclusions and recommendations:

“The seismic hazard for the study area of the proposed water supply project is low to moderate. Preliminary estimates of the ground shaking expected at a probability of exceedence of 2% in fifty (50) years indicate relatively modest amplitudes of motion, with peak ground accelerations of about 10% of the acceleration due to gravity. Much work on seismic hazard evaluation has already been done for this area in connection with the Pickering nuclear power plant, and is relevant to the selection of design ground motion levels for this project”.



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Relevant figures from the above referenced Pickering Power Plant Upgrade Reports, showing the seismicity of the Lake Ontario region, recent (1980-1997) seismicity events, and the Pickering mean ground motion spectrum probability, are shown on the attached Figures 1, 2 and 3 respectively (Appendix B).

1.6 Precast Concrete Pipe Laying Alternative

This option involves placement of a precast segmental concrete pipeline within a trench that was dredged, excavated or blasted into the sub-bottom. From discussions with contractors it is our understanding that owing to market consolidation in the marine contracting sector in the past few years, there are a limited number of qualified contractors with suitable marine pipe laying experience; hence the Regions may be faced with limited competition for this alternative.

Both the geotechnical and the geophysical survey (see Volume 1) established that the lake bottom conditions are quite variable. The surface of the bedrock lies at depth less than 4 m to as much as 16 m to a distance of about 2300 m off-shore and is exposed or is covered with only a few centimetres of loose sandy mud and some aquatic vegetation throughout almost the entire remaining length of the outfall pipe. In the area of the two buried rock valleys, the overburden soils are very weak and compressible to a depth of 14 m to 16 m below lake bottom.

The geotechnical conditions that exist below the lake bottom suggest potential problems with the excavation of the trenches and also with the support of the pipes.

1.6.1 Excavation

In areas where the depth to the surface of the rock is less than the proposed 6 m depth of the trench, then, in all likelihood, given the depth of water and the relatively fresh nature of bedrock, a trench into the lakebed could not be excavated without resorting to blasting. The submarine drilling, blasting, mucking, pipe laying and backfilling work would all have to be carried out within the confines of a pair of submerged silt curtains. It is expected that other environmental constraints would also be imposed on such an operation, but a review of these is not within the scope of this assignment. In addition to environmental issues, blasting design would have to take into consideration, the vibration effects, and proximity of the near shore structures of the WPCP.

It is expected that the excavated side slopes of the submerged trenches in the clay till encountered at lake bottom in Boreholes 203 and 204 will be temporarily stable at an angle of 2.0 horizontal in 1.0 vertical. Flatter, possibly 3 to 4 horizontal in 1 vertical side slopes are expected in the granular soils similar to those encountered in Borehole 205. Considerably flatter, possibly 6:1 slopes may be needed in the very soft and very loose deposits found in the two buried rock valleys (BHs 202 and 206).

The rock cut trenches would be expected to stand open and unsupported for short periods on near vertical faces, although sloughing of loose rock, rock wedges and blocks as well as over break would be expected, particularly if poor blasting methods or widely spaced blast holes are employed.

Contractors should also bear in mind that wave and storm action could result in sloughing of sediments, loose rock, etc., into the trench and this should be considered when determining the length of trench to be left open overnight or for extended periods.



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The blast pattern and load factors should be designed by a specialist blasting engineer with submarine experience. The pattern, load factors and delays must take into consideration, among other factors, the depth of water, rock mass properties, desired fragmentation, vibrations and wall control, as well as environmental issues. It may be advantageous to perform test blasts in the rock formation before deciding on a production pattern. To protect the nearby structures and the existing outfall, vibration monitoring on the structures and submarine monitoring on the existing outfall pipeline and diffuser is recommended. The allowable ground velocities and accelerations would have to be established based on a review of the design of the structures.

It should be noted that construction in water depths greater than 20 m is beyond the working limit of most spudded and jack-up barges available in this country and, therefore, presents considerable constructability issues. The design and execution of submarine works in this depth of water requires highly specialized expertise and equipment.

As an alternative to blasting, the CARDOX method of rock fragmentation could be considered for the removal of the rock. This method, which has been successfully used on numerous underwater applications, breaks up the rock by the conversion of liquid carbon dioxide (CO2) into gas which is accompanied by a 600 time increase in volume. It involves the drilling of holes at close intervals to a maximum depth of 1.5 to1.8 m at a time (maximum lift thickness) and inserting tubes containing the liquid CO2 followed by the activation of the conversion process. The main disadvantage of this method is its high cost.

1.6.2 Pipe Support

Supporting the pipe on the bedrock and the lake bed deposits found outside the buried rock valleys should not be a problem. Pipe bedding and backfill around and above the pipe should be 25 mm to 50 mm size clear stone. The minimum thickness of the bedding material below the pipe invert should be 300 mm on rock, 600 mm on overburden and should occupy the full width of the excavated trench. The thickness of the clear stone cover above the pipe should be 300 mm. The remaining portion of the trench could be backfilled with the excavated soil on top of which a 500 mm thick layer of rip-rap should be placed to protect the pipe from damage from the dropping of anchors and the like.

In contrast, potentially serious problems with supporting the pipes on the lakebed are expected in the areas of the two buried rock valleys (Boreholes 202 and 206). At these locations, the very loose and very soft organic deposits offered no resistance to the drilling rods, casings and sampling tools all of which sunk into these deposits under their own weight. It is, therefore, expected that even if the bedding material (a minimum thickness of 750 mm) and the pipe laid on them will find equilibrium, that equilibrium will be reached only after considerable (possibly in excess of a metre) settlement. These deformations will likely be excessive for the pipe joints. These deposits are also prone to liquefaction and, therefore, supporting the pipes on them will be risky in case of a seismic event.

1.7 Statement of Limitations

The Statement of Limitations, as quoted in Appendix C, is an integral part of this report.



13

For and on behalf of Coffey Geotechnics Inc.

Ivan P. Lieszkowszky, P.Eng., FEIC Janos Garami, P.Eng., FEC Senior Principal Senior Geotechnical Engineer



14

LIST OF REFERENCES

[1] Franklin, J. A.: “Rock Engineering”, McGraw-Hill, 1989, p.41 [2] Morton, J.D., Lo, K.Y. and Belshaw, D.: “Rock performance consideration for shallow tunnels in

bedded shales with high lateral Stresses”, Proceedings, 12th Canadian Rock Mechanics Symposium, Kingston, Ontario, 1975.

[3] Lo, K.Y. and Morton, J.D.: “Tunnels in bedded rock with high horizontal stresses”, Canadian

Geotechnical Journal, Vol. 13, 1976. [4] Lo, K.Y., Palmer, J.H.L. and Quigley, R.M.: “Time-dependent deformation of shaley rocks in

southern Ontario”, Canadian Geotechnical Journal, Vol. 15, 1978. [5] Franklin, J.A. and Hungr, O.: “Rock Stresses in Canada, their relevance in engineering projects”,

Rock Mechanics, by Springer-Verlag, 1978. [6] Lo, K.Y., Cooke, B.H. and Dunbar, D.D.: “Design of buried structures in squeezing rock in Toronto,

Canada”, Canadian Geotechnical Journal, Vol. 24, 1987. [7] J.A. Franklin: “Evaluation of Shales for Construction Purposes”, MOT, 1983

[8] Lo, K.Y and Yuen, C.M.K. Design of tunnel lining in rock for long term time effects. Canadian Geotechnical Journal, Volume 18, 1981

[9] Lo, K.Y. and Lukajic, Boro. Predicted and measured stresses and displacements around the Darlington Intake Tunnel.

[10] Groundwater Resources of the Duffin Creek – Rouge River Drainage Basins. Ministry of the Environment, Ontario, Water Resources Report 8.1977.

Appendix A

Borehole Location Plan – Drawing 1 Bedrock Geology and Topography – Drawing 2

Inferred Geological Profile – Drawing 3 RQD Histogram – Drawings 4,7,10 RMR Histogram – Drawings 5,8,11

Hydraulic Conductivity Profile – Drawings 6,9,12 Rock Convergence Points – Drawing 13

Appendix B

Seismicity of Lake Ontario Region Figure 1,2,3 Summary of Hydraulic ConductivityTest Results Table D5

Rock Mass Rating (RMR) Table D6 Summary of Locations Where Gas Encountered Table D7

r, 4.

All events 45 0

or + + + + 0 O<M<2

44° 40' + + + + + 1 <:5 2<M<3

44°20' ++ 0 3<M<4

44° ... 4<M<5

43° 40' • ~ 5-:::M<6

43°20' Si~ . 0t -t

43° + + o 0 0 + 0 0

42°40' 0 +

42 0 20' + f+ 0

42° +

-81° -80 0 -79° -78 0 -77 0 -76°

Figure 1 - Seismicity of Lake Ontario region to 1997 (all known events), and geophysical lineaments described by Mohajer (1993): 1- Niagara-Pickering Linear Zone, 2-Burlington-Toronto Magnetic Lineament, 3-Georgian Bay Linear Zone, 4-Hamilton-Presqu'ile Lineament, 5-Wilson-Port Hope Lineament, 6-ClarendonLinden faultllineament.

Events 1 980-1 997

+

1

O<M<2

+ 2<M<3

o 3<M<4

* Site

Figure 2 - Recent (ie. accurately-located) seismicity of Western Lake Ontario region (1980-1997), and geophysical lineaments described by Mohajer (1993): 1-Niagara-Pickering Linear Zone, 2-Burlington-Toronto Magnetic Lineament, 3-Georgian Bay Linear Zone, 4-Hamilton-Presqu'ile Lineament, 5-Wilson-Port Hope Lineament.

r.

Pickering Mean Ground Motion Spectrum probability = 10% in 100 years

1000~----------------------------------~

... """" ..... ""."" .. """.""."." ....... " ...... _ ...................... ,," .. """."""" ........ " ... .

10

1 +---~~~~~~--~~~~~~--~~~~TTrl

0.1 1 10 100 Frequency (Hz)

1-- Atkinson, 1994 ............... Geomatrix, 1997

Figure 3 - Mean seismic hazard results for an exceedence probability level of 10% in 100 years, based on previous studies for Pickering (Atkinson, 1990, 1994; Geomatrix, 1997). Plot shows amplitudes of ground acceleration as a function of vibrational frequency. Note the peak ground acceleration (plotted at 100 Hz) is about 50 cm/s2

, or 5% of the gravitational acceleration.

GEOTMARK00171AA

Table D5: Summary of Hydraulic Conductivity Test Results

Test Zone Elevation Gauge Pressure Hydraulic Conductivity

(m) (psi) (cm/s)

80 k=7.72E-6

85 k=5.82E-6

95 k=7.20E-6

80 k=4.35E-6

85 k=5.06E-6

95 k=6.40E-6

80 k=4.03E-6

85 k=4.05E-6

95 k=3.91E-6

80 k=3.81E-6

85 k=3.54E-6

95 k=4.07E-6

50 no water take

55 k=1.29E-6

65 k=2.18E-6

50 no water take

55 k=1.29E-6

65 k=2.18E-6

45 no water take

50 no water take

60 no water take

40 no water take

45 no water take

55 k=3.13E-7

35 no water take

40 no water take

50 k=3.59E-6

20 no water take

25 no water take

35 no water take

20 k=2.15E-6

25 no water take

35 k=6.15E-7

20 no water take

25 no water take

35 k=9.23E-7

20 no water take

25 no water take

35 k=6.15E-7

Values measured in Whitby Formation

204 24.0-27.0

204 27.0-30.0

204 30.0-33.0

204 33.0-36.0

203 27.0-30.0

203 30.0-33.0

203 33.0-36.0

202 33.0-36.0

203 24.0-27.0

203 24.0-27.0

202 30.0-33.0

Borehole

202 24.0-27.0

202 27.0-30.0

Table D5: Summary of Hydraulic Conductivity Test Results (continued)


(m) (psi) (cm/s)

15 no water take

27 no water take

41 no water take

12 no water take

26 no water take

37 k=1.74E-5

11 no water take

22 no water take

33 no water take

10 no water take

19 no water take

29 k=7.41E-6

10 no water take

20 k=8.60E-6

30 k=5.01E-6

9 no water take

18 k=1.08E-5

26 k=4.14E-6

8 no water take

15 no water take

22 k=1.95E-6

6 k=4.09E-3

12 k=2.95E-3

19 k=2.26E-3

12 k=1.79E-6

24 k=4.49E-6

36 k=3.29E-6

11 no water take

22 no water take

33 k=4.14E-6

9 no water take

18 no water take

27 no water take

8 no water take

16 k=3.81E-4

24 k=3.85E-4


206A 21.0-24.0

206A

207

24.0-27.0

206A 27.0-30.0

206 27.0-30.0

206 30.0-33.0

206 33.0-36.0

205 29.0-32.0

205 32.0-35.0

206 24.0-27.0

205 26.0-29.0

Borehole

205 23.0-26.0

206A 30.0-33.0

Unable to perform tests due to gas pressure in borehole.



(m) (psi) (cm/s)

13 k=1.65E-6

25 k=4.31E-6

38 k=3.11E-6

12 k=1.43E-5

24 no water take

36 k=3.29E-5

22 k=3.41E-5

32 k=1.74E-5

39 k=1.10E-5

9 k=2.39E-5

19 k=3.96E-5

28 k=3.46E-5

8 k=4.85E-4

16 k=2.56E-4

25 k=2.19E-4

12 no water take

27 k=1.32E-5

37 k=4.94E-6

11 k=1.85E-5

22 k=5.46E-5

33 k=6.37E-5

9 no water take

19 k=6.85E-5

28 k=6.07E-5

8 no water take

16 k=1.35E-5

25 k=2.20E-5

12 k=1.03E-4

24 k=1.52E-4

36 k=1.49E-4

11 no water take

22 k=2.15E-5

33 k=2.83E-5

9 k=4.90E-5

18 k=2.80E-4

28 k=5.70E-4


301

302 24.0-27.0

21.0-24.0

403 27.0-30.0

24.0-27.0

402 27.0-30.0

402 30.0-33.0

302 30.0-33.0

302 33.0-36.0

402 21.0-24.0

403 24.0-27.0

Unable to perform tests at higher elevations due to gas pressure in

borehole

301

403 21.0-24.0

Borehole

402

302 27.0-30.0



(m) (psi) (cm/s)

8 no water take

16 k=2.84E-4

24 k=5.73E-4


403 30.0-33.0

Borehole

Table D6: Rock Mass Rating (RMR) 1 of 11

BH202

Strength of Intact Spacing of Condition of Total Rock Mass

from to from to Rock Material Discontinuities Discontinuities Rating Class

R1 29.6 30.4 49.5 48.7 7 3 5 10 0 -5 20 IV

R2 30.4 30.8 48.7 48.3 7 3 5 10 0 -5 20 IV

R3 30.8 32.2 48.3 46.9 7 3 5 10 0 -5 20 IV

R4 32.2 33.7 46.9 45.4 7 17 8 10 0 -5 37 IV

R5 33.7 35.2 45.4 43.9 7 20 8 10 0 -5 40 IV

R6 35.2 36.8 43.9 42.3 7 20 10 20 0 -5 52 III

R7 36.8 38.3 42.3 40.8 4 20 10 10 0 -5 39 IV

R8 38.3 39.8 40.8 39.3 7 13 10 10 0 -5 35 IV

R9 39.8 41.3 39.3 37.8 4 13 8 10 0 -5 30 IV

R10 41.3 42.8 37.8 36.3 7 17 10 10 0 -5 39 IV

R11 42.8 44.4 36.3 34.7 12 13 8 10 0 -5 38 IV

R12 44.4 46.1 34.7 33.0 7 17 8 10 0 -5 37 IV

R13 46.1 47.6 33.0 31.5 7 20 10 10 0 -5 42 III

R14 47.6 49.1 31.5 30.0 7 17 8 10 0 -5 37 IV Tunneling

R15 49.1 50.7 30.0 28.4 7 20 10 20 0 -5 52 III Zone

R16 50.7 52.2 28.4 26.9 4 20 8 20 0 -5 47 III I

R17 52.2 53.7 26.9 25.4 7 17 10 20 0 -5 49 III I

R18 53.7 55.2 25.4 23.9 7 17 8 20 0 -5 47 III I

R19 55.2 56.7 23.9 22.4 7 17 10 25 0 -5 54 III El. 24.0-28.0

R20 56.7 58.3 22.4 20.8 7 17 10 25 0 -5 54 III (m)

R21 58.3 59.8 20.8 19.3 7 17 10 25 0 -5 54 III

R22 59.8 61.3 19.3 17.8 7 17 10 25 0 -5 54 III

R23 61.3 62.9 17.8 16.2 7 17 10 25 0 -5 54 III

Average RMR = 41

denotes estimated value based on surrounding rock (due to lack of data or similar)

denotes conservative estimated value

'flowing' rating assumed as worst case scenario, given location of tunnel below Lake Ontario

note that based on packer test calculations and k values, realistic ratings may be as high as 10-15

RATING

Run RQD GroundwaterStrike and Dip

Orientations

Depth BCL (m) Elevation (m)


BH203



R1 21.1 21.4 57.8 57.5 2 3 5 10 0 -5 15 V

R2 21.4 23.0 57.5 56.0 2 8 5 10 0 -5 20 IV

R3 23.0 24.5 56.0 54.5 2 13 8 10 0 -5 28 IV

R4 24.5 26.0 54.5 52.9 2 13 8 10 0 -5 28 IV

R5 26.0 27.5 52.9 51.4 2 13 8 10 0 -5 28 IV

R6 27.5 29.0 51.4 49.9 2 20 8 10 0 -5 35 IV

R7 29.0 30.6 49.9 48.4 2 17 8 10 0 -5 32 IV

R8 30.6 32.1 48.4 46.8 4 20 8 10 0 -5 37 IV

R9 32.1 33.6 46.8 45.3 2 20 10 20 0 -5 47 III

R10 33.6 35.1 45.3 43.8 7 17 8 20 0 -5 47 III

R11 35.1 36.7 43.8 42.3 4 20 10 20 0 -5 49 III

R12 36.7 38.2 42.3 40.7 7 20 10 20 0 -5 52 III

R13 38.2 39.7 40.7 39.2 7 20 10 20 0 -5 52 III

R14 39.7 41.2 39.2 37.7 4 20 10 25 0 -5 54 III

R15 41.2 42.7 37.7 36.2 4 20 10 25 0 -5 54 III

R16 42.7 44.3 36.2 34.6 7 20 10 25 0 -5 57 III

R17 44.3 45.8 34.6 33.1 7 20 10 25 0 -5 57 III

R18 45.8 47.3 33.1 31.6 4 20 10 25 0 -5 54 III

R19 47.3 48.8 31.6 30.1 12 20 10 25 0 -5 62 II Tunneling

R20 48.8 50.4 30.1 28.5 7 20 10 25 0 -5 57 III Zone

R21 50.4 52.0 28.5 26.9 4 20 10 25 0 -5 54 III I

R22 52.0 53.5 26.9 25.4 4 20 10 25 0 -5 54 III I

R23 53.5 55.0 25.4 23.9 7 20 10 25 0 -5 57 III I

R24 55.0 56.5 23.9 22.4 7 20 10 25 0 -5 57 III El. 24.0-28.0

R25 56.5 58.0 22.4 20.9 7 20 10 25 0 -5 57 III (m)

R26 58.0 59.6 20.9 19.3 7 20 10 25 0 -5 57 III

Average RMR = 46






Orientations

RATING



BH204



R1 24.5 25.2 54.6 53.8 2 3 5 0 0 -5 5 V

R2 25.2 26.0 53.8 53.1 4 8 5 10 0 -5 22 IV

R3 26.0 27.6 53.1 51.5 2 13 5 10 0 -5 25 IV

R4 27.6 29.1 51.5 50.0 2 17 8 10 0 -5 32 IV

R5 29.1 30.6 50.0 48.5 2 13 8 10 0 -5 28 IV

R6 30.6 32.1 48.5 47.0 2 13 8 10 0 -5 28 IV

R7 32.1 33.7 47.0 45.4 2 13 8 10 0 -5 28 IV

R8 33.7 35.2 45.4 43.9 2 13 8 10 0 -5 28 IV

R9 35.2 36.7 43.9 42.4 2 20 8 10 0 -5 35 IV

R10 36.7 38.2 42.4 40.9 4 13 8 10 0 -5 30 IV

R11 38.2 39.8 40.9 39.3 4 20 10 20 0 -5 49 III

R12 39.8 41.3 39.3 37.8 7 20 10 20 0 -5 52 III

R13 41.3 42.8 37.8 36.3 7 20 15 25 0 -5 62 II

R14 42.8 44.3 36.3 34.8 7 20 15 25 0 -5 62 II

R15 44.3 45.8 34.8 33.2 4 20 15 25 0 -5 59 III

R16 45.8 47.4 33.2 31.7 4 20 10 25 0 -5 54 III

R17 47.4 48.9 31.7 30.2 4 20 15 25 0 -5 59 III Tunneling

R18 48.9 50.4 30.2 28.7 7 20 10 25 0 -5 57 III Zone

R19 50.4 51.9 28.7 27.2 7 20 15 25 0 -5 62 II I

R20 51.9 53.5 27.2 25.6 7 20 15 25 0 -5 62 II I

R21 53.5 55.0 25.6 24.1 4 20 15 25 0 -5 59 III I

R22 55.0 56.5 24.1 22.6 7 20 15 25 0 -5 62 II El. 24.0-28.0

R23 56.5 58.0 22.6 21.1 7 20 15 25 0 -5 62 II (m)Average RMR = 44






Orientations

RATING



BH205



R1 22.9 24.2 55.1 53.8 2 3 5 0 0 -5 5 V

R2 24.5 26.1 53.5 52.0 2 13 5 10 0 -5 25 IV

R3 26.1 27.6 52.0 50.4 2 8 5 10 0 -5 20 IV

R4 27.6 29.1 50.4 48.9 2 3 5 10 0 -5 15 V

R5 29.1 30.6 48.9 47.4 2 8 8 10 0 -5 23 IV

R6 30.6 32.2 47.4 45.9 2 13 8 10 0 -5 28 IV

R7 32.2 33.7 45.9 44.3 4 13 8 10 0 -5 30 IV

R8 33.7 35.2 44.3 42.8 2 13 8 10 0 -5 28 IV

R9 35.2 36.7 42.8 41.3 2 13 8 10 0 -5 28 IV

R10 36.7 38.3 41.3 39.8 2 13 8 10 0 -5 28 IV

R11 38.3 39.8 39.8 38.3 4 13 8 10 0 -5 30 IV

R12 39.8 41.3 38.3 36.7 2 17 8 10 0 -5 32 IV

R13 41.3 42.8 36.7 35.2 7 17 8 10 0 -5 37 IV

R14 42.8 44.3 35.2 33.7 2 20 10 20 0 -5 47 III

R15 44.3 45.9 33.7 32.2 7 20 10 20 0 -5 52 III

R16 45.9 47.4 32.2 30.6 12 20 10 20 0 -5 57 III Tunneling

R17 47.4 48.9 30.6 29.1 7 20 10 20 0 -5 52 III Zone

R18 48.9 50.4 29.1 27.6 4 20 10 20 0 -5 49 III I

R19 50.4 52.0 27.6 26.1 7 20 15 25 0 -5 62 II I

R20 52.0 53.5 26.1 24.5 7 20 15 25 0 -5 62 II I

R21 53.5 55.0 24.5 23.0 7 20 15 25 0 -5 62 II I

R22 55.0 56.5 23.0 21.5 7 20 15 25 0 -5 62 II El. 24.0-28.0

R23 56.5 58.1 21.5 20.0 7 20 15 25 0 -5 62 II (m)

R24 58.1 59.6 20.0 18.4 7 20 15 25 0 -5 62 II

R25 59.6 61.1 18.4 16.9 7 20 15 25 0 -5 62 II

Average RMR = 41





Strike and Dip

Orientations

RATING

Run RQD GroundwaterDepth BCL (m) Elevation (m)


BH206



R1 39.3 39.6 39.5 39.2 2 8 8 10 0 -5 23 IV

R2 39.6 41.1 39.2 37.6 2 17 8 10 0 -5 32 IV

R3 41.1 42.7 37.6 36.1 2 13 8 10 0 -5 28 IV

R4 42.7 44.2 36.1 34.6 2 13 8 10 0 -5 28 IV

R5 44.2 45.7 34.6 33.1 2 17 10 10 0 -5 34 IV

R6 45.7 47.2 33.1 31.5 4 20 10 20 0 -5 49 III

R7 47.2 48.8 31.5 30.0 4 20 10 20 0 -5 49 III Tunneling

R8 48.8 50.3 30.0 28.5 7 20 10 20 0 -5 52 III Zone

R9 50.3 51.8 28.5 27.0 7 20 10 20 0 -5 52 III I

R10 51.8 53.3 27.0 25.5 7 20 10 20 0 -5 52 III I

R11 53.3 54.9 25.5 23.9 7 20 15 25 0 -5 62 II I

R12 54.9 56.4 23.9 22.4 7 20 15 25 0 -5 62 II El. 24.0-28.0

R13 56.4 57.9 22.4 20.9 7 20 15 25 0 -5 62 II (m)

R14 57.9 59.4 20.9 19.4 7 20 15 25 0 -5 62 II

Average RMR = 46





Strike and Dip

Orientations

RATING

Run RQD GroundwaterDepth BCL (m) Elevation (m)


BH206A



R1 25.4 26.0 53.6 53.0 2 3 5 10 0 -5 15 V

R2 26.0 27.5 53.0 51.5 2 3 5 10 0 -5 15 V

R3 27.5 29.1 51.5 49.9 4 8 5 10 0 -5 22 IV

R4 29.1 30.6 49.9 48.4 2 13 8 10 0 -5 28 IV

R5 30.6 32.1 48.4 46.9 4 13 8 10 0 -5 30 IV

R6 32.1 33.6 46.9 45.4 4 17 8 10 0 -5 34 IV

R7 33.6 35.2 45.4 43.8 4 13 8 10 0 -5 30 IV

R8 35.2 36.7 43.8 42.3 2 13 8 10 0 -5 28 IV

R9 36.7 38.2 42.3 40.8 2 13 8 10 0 -5 28 IV

R10 38.2 39.7 40.8 39.3 2 13 8 10 0 -5 28 IV

R11 39.7 41.2 39.3 37.8 4 13 8 10 0 -5 30 IV

R12 41.2 42.8 37.8 36.2 2 17 8 10 0 -5 32 IV

R13 42.8 44.3 36.2 34.7 4 13 8 10 0 -5 30 IV

R14 44.3 45.8 34.7 33.2 2 17 8 10 0 -5 32 IV

R15 45.8 47.3 33.2 31.7 4 13 8 10 0 -5 30 IV

R16 47.3 48.9 31.7 30.1 7 13 5 10 0 -5 30 IV Tunneling

R17 48.9 50.4 30.1 28.6 7 20 8 10 0 -5 40 IV Zone

R18 50.4 51.9 28.6 27.1 7 17 10 20 0 -5 49 III I

R19 51.9 53.4 27.1 25.6 7 20 15 25 0 -5 62 II I

R20 53.4 55.0 25.6 24.0 7 20 15 25 0 -5 62 II I

R21 55.0 56.5 24.0 22.5 12 20 15 25 0 -5 67 II El. 24.0-28.0

R22 56.5 58.0 22.5 21.0 7 20 15 25 0 -5 62 II (m)

R23 58.0 59.5 21.0 19.5 7 17 15 25 0 -5 59 III

Average RMR = 37





RATING


Orientations



BH207



R1 26.0 27.4 52.9 51.5 1 3 5 0 0 -5 4 V

R2 27.4 29.0 51.5 49.9 2 13 8 10 0 -5 28 IV

R3 29.0 30.5 49.9 48.4 2 20 8 10 0 -5 35 IV

R4 30.5 32.0 48.4 46.9 2 17 8 10 0 -5 32 IV

R5 32.0 33.5 46.9 45.4 2 13 8 10 0 -5 28 IV

R6 33.5 35.1 45.4 43.8 4 13 8 10 0 -5 30 IV

R7 35.1 36.6 43.8 42.3 4 17 8 10 0 -5 34 IV

R8 36.6 38.1 42.3 40.8 2 13 8 10 0 -5 28 IV

R9 38.1 39.6 40.8 39.3 2 20 8 10 0 -5 35 IV

R10 39.6 41.1 39.3 37.8 2 17 8 10 0 -5 32 IV

R11 41.1 42.7 37.8 36.2 2 20 8 10 0 -5 35 IV

R12 42.7 44.2 36.2 34.7 2 17 8 10 0 -5 32 IV

R13 44.2 45.7 34.7 33.2 2 13 8 10 0 -5 28 IV

R14 45.7 47.2 33.2 31.7 2 20 15 20 0 -5 52 III

R15 47.2 48.8 31.7 30.1 2 17 15 20 0 -5 49 III Tunneling

R16 48.8 50.3 30.1 28.6 4 20 15 20 0 -5 54 III Zone

R17 50.3 51.8 28.6 27.1 2 20 15 20 0 -5 52 III I

R18 51.8 53.3 27.1 25.6 7 20 15 20 0 -5 57 III I

R19 53.3 54.9 25.6 24.0 7 20 15 20 0 -5 57 III I

R20 54.9 56.4 24.0 22.5 7 20 20 25 0 -5 67 II El. 24.0-28.0

R21 56.4 57.9 22.5 21.0 7 20 20 25 0 -5 67 II (m)

R22 57.9 59.4 21.0 19.5 7 20 20 25 0 -5 67 II

Average RMR = 41





RATING

RunDepth BCL (m) Elevation (m)

RQD GroundwaterStrike and Dip

Orientations


BH301



R1 24.5 25.9 54.6 53.2 1 3 5 0 0 -5 4 V

R2 25.9 27.4 53.2 51.7 1 8 5 10 0 -5 19 V

R3 27.4 29.0 51.7 50.1 2 17 8 10 0 -5 32 IV

R4 29.0 30.5 50.1 48.6 2 8 8 10 0 -5 23 IV

R5 30.5 32.0 48.6 47.1 2 13 8 10 0 -5 28 IV

R6 32.0 33.5 47.1 45.6 2 17 8 10 0 -5 32 IV

R7 33.5 35.1 45.6 44.0 2 17 10 10 0 -5 34 IV

R8 35.1 36.6 44.0 42.5 2 17 8 10 0 -5 32 IV

R9 36.6 38.1 42.5 41.0 2 17 8 10 0 -5 32 IV

R10 38.1 39.6 41.0 39.5 4 17 10 20 0 -5 46 III

R11 39.6 41.1 39.5 38.0 2 20 10 20 0 -5 47 III

R12 41.1 42.7 38.0 36.4 2 20 10 20 0 -5 47 III

R13 42.7 44.2 36.4 34.9 2 17 10 20 0 -5 44 III

R14 44.2 45.7 34.9 33.4 4 20 10 20 0 -5 49 III

R15 45.7 47.2 33.4 31.9 2 20 10 20 0 -5 47 III

R16 47.2 48.8 31.9 30.3 2 17 10 20 0 -5 44 III Tunneling

R17 48.8 50.3 30.3 28.8 4 17 10 20 0 -5 46 III Zone

R18 50.3 51.8 28.8 27.3 4 20 10 20 0 -5 49 III I

R19 51.8 53.3 27.3 25.8 7 20 20 25 0 -5 67 II I

R20 53.3 54.9 25.8 24.2 7 20 20 25 0 -5 67 II I

R21 54.9 56.4 24.2 22.7 7 20 20 25 0 -5 67 II El. 24.0-28.0

R22 56.4 57.9 22.7 21.2 7 20 20 25 0 -5 67 II (m)

R23 57.9 59.4 21.2 19.7 7 20 20 25 0 -5 67 II

Average RMR = 43





RATING



Orientations


BH302



R1 23.4 24.4 55.4 54.4 1 3 5 10 0 -5 14 V

R2 24.4 25.9 54.4 52.9 1 3 5 10 0 -5 14 V

R3 25.9 27.4 52.9 51.4 1 3 5 10 0 -5 14 V

R4 27.4 29.0 51.4 49.8 1 3 5 10 0 -5 14 V

R5 29.0 30.5 49.8 48.3 1 3 5 10 0 -5 14 V

R6 30.5 32.0 48.3 46.8 1 3 5 10 0 -5 14 V

R7 32.0 33.5 46.8 45.3 1 3 5 10 0 -5 14 V

R8 33.5 35.1 45.3 43.7 1 3 5 10 0 -5 14 V

R9 35.1 36.6 43.7 42.2 1 3 5 10 0 -5 14 V

R10 36.6 38.1 42.2 40.7 1 3 5 10 0 -5 14 V

R11 38.1 39.6 40.7 39.2 1 3 5 10 0 -5 14 V

R12 39.6 41.1 39.2 37.7 1 3 5 10 0 -5 14 V

R13 41.1 42.7 37.7 36.1 1 3 5 10 0 -5 14 V

R14 42.7 44.2 36.1 34.6 1 3 5 10 0 -5 14 V

R15 44.2 45.7 34.6 33.1 2 3 8 20 0 -5 28 IV

R16 45.7 47.2 33.1 31.6 2 3 8 20 0 -5 28 IV

R17 47.2 48.8 31.6 30.0 2 8 8 20 0 -5 33 IV Tunneling

R18 48.8 50.3 30.0 28.5 2 10 8 20 0 -5 35 IV Zone

R19 50.3 51.8 28.5 27.0 7 8 8 20 0 -5 38 IV I

R20 51.8 53.3 27.0 25.5 7 8 8 20 0 -5 38 IV I

R21 53.3 54.9 25.5 23.9 7 3 8 20 0 -5 33 IV I

R22 54.9 56.4 23.9 22.4 7 8 8 20 0 -5 38 IV El. 24.0-28.0

R23 56.4 57.9 22.4 20.9 7 3 8 20 0 -5 33 IV (m)Average RMR = 22





BH302 Given relatively nonexistant overburden and highly fractured/weathered state of the bedrock, borehole location may be situated on fossil valley cliff (ie edge of

paleovalley feature). If so, consideration should be given to the possibility of presence of vertical weathering/relaxation joints in the rock mass at this location

that may have formed prior to lake level rise.

RATING


Orientations



BH402



R1 26.1 27.5 52.9 51.5 2 13 5 10 0 -5 25 IV

R2 27.5 29.0 51.5 50.0 2 3 5 10 0 -5 15 V

R3 29.0 30.6 50.0 48.4 2 13 8 10 0 -5 28 IV

R4 30.6 32.1 48.4 46.9 2 17 8 10 0 -5 32 IV

R5 32.1 33.6 46.9 45.4 2 13 5 10 0 -5 25 IV

R6 33.6 35.1 45.4 43.9 2 3 8 10 0 -5 18 V

R7 35.1 36.7 43.9 42.3 2 13 8 10 0 -5 28 IV

R8 36.7 38.2 42.3 40.8 2 13 8 10 0 -5 28 IV

R9 38.2 39.7 40.8 39.3 4 17 8 10 0 -5 34 IV

R10 39.7 41.2 39.3 37.8 4 13 8 10 0 -5 30 IV

R11 41.2 42.7 37.8 36.3 4 13 8 10 0 -5 30 IV

R12 42.7 44.3 36.3 34.7 2 13 8 10 0 -5 28 IV

R13 44.3 45.8 34.7 33.2 4 17 10 20 0 -5 46 III

R14 45.8 47.3 33.2 31.7 4 17 10 20 0 -5 46 III

R15 47.3 48.8 31.7 30.2 2 13 10 20 0 -5 40 IV Tunneling

R16 48.8 50.4 30.2 28.6 2 17 10 20 0 -5 44 III Zone

R17 50.4 51.9 28.6 27.1 2 13 10 20 0 -5 40 IV I

R18 51.9 53.4 27.1 25.6 2 17 10 20 0 -5 44 III I

R19 53.4 54.9 25.6 24.1 7 20 15 25 0 -5 62 II I

R20 54.9 56.5 24.1 22.5 7 20 15 25 0 -5 62 II El. 24.0-28.0

R21 56.5 58.0 22.5 21.0 7 20 15 25 0 -5 62 II (m)R22 58.0 59.5 21.0 19.5 7 20 15 25 0 -5 62 II

Average RMR = 38





RATING



Orientations


BH403



R1 30.6 32.1 48.3 46.8 2 8 5 0 0 -5 10 V

R2 32.1 33.6 46.8 45.3 2 8 5 10 0 -5 20 IV

R3 33.6 35.2 45.3 43.7 2 8 5 10 0 -5 20 IV

R4 35.2 36.7 43.7 42.2 2 8 5 10 0 -5 20 IV

R5 36.7 38.2 42.2 40.7 2 13 5 10 0 -5 25 IV

R6 38.2 39.7 40.7 39.2 2 13 5 10 0 -5 25 IV

R7 39.7 41.2 39.2 37.7 4 17 8 10 0 -5 34 IV

R8 41.2 42.8 37.7 36.1 4 8 8 10 0 -5 25 IV

R9 42.8 44.3 36.1 34.6 4 3 5 10 0 -5 17 V

R10 44.3 45.8 34.6 33.1 4 8 5 10 0 -5 22 IV

R11 45.8 47.3 33.1 31.6 2 3 8 10 0 -5 18 V

R12 47.3 48.9 31.6 30.0 2 8 8 10 0 -5 23 IV Tunneling

R13 48.9 50.4 30.0 28.5 4 3 5 10 0 -5 17 V Zone

R14 50.4 51.9 28.5 27.0 4 13 8 10 0 -5 30 IV I

R15 51.9 53.4 27.0 25.5 7 17 8 10 0 -5 37 IV I

R16 53.4 55.0 25.5 23.9 2 13 8 10 0 -5 28 IV I

R17 55.0 56.5 23.9 22.4 4 13 8 10 0 -5 30 IV El. 24.0-28.0

R18 56.5 58.0 22.4 20.9 7 13 8 10 0 -5 33 IV (m)

R19 58.0 59.5 20.9 19.4 7 20 10 20 0 -5 52 III

Average RMR = 26





RATING



Orientations

GEOTMARK00171AA

Table D7: Summary of Locations Where Gas Encountered

CH4 (%LEL) CO2 (vol %) O2 (vol %) CO (ppm) H2S (ppm) IBL (ppm)

202 36.3 Lindsay 45 min (dissipate) - - - - - - -

204 30.2 Lindsay 1 hr (dissipate) - - - - - - -

39.8 Whitby overnight (dissipate) - - - - - - -

32.0 Lindsay 30 min (burn) - - - - - - -

27.7 Lindsay 45 min (burn) - - - - - - -

39.2 Whitby 2 hr (burn) - - - - - - -

37.6 Whitby 2 hr (burn) - - - - - - -

36.1 Whitby 2 hr (burn) - - - - - - -

31.5 Whitby 20 min (burn) - - - - - - -

37.8 Whitby 20 min (burn) 4 100 0.58 2.2 0 0 0

36.2 Whitby overnight (dissipate) - 48 - - - - -

30.1 Whitby 1.5 hrs (burn) 20 100 5.0 0.5 0 0 0

27.1 Whitby 30 min (burn) 10 100 - - - - -

22.5 Lindsay 7 hrs (burn) + overnight (dissipate) 18 100 5 0.4 0 0 9

21.0 Lindsay 20 min (dissipate) - 55 - - - - -

30.1 Whitby 10 min (dissipate) - 100 - - - - -

22.5* Lindsay 3 hrs (burn) + [2x] overnight (dissipate) - 100 - - - - -


25.4* Lindsay/Whitby overnight (dissipate) 35** 100 - - - - -

33.1 Whitby overnight (dissipate) - - - - - - -

27.0 Lindsay 1 hr (burn) - - - - - - -


25.5* Whitby 1 hr (dissipate) 40** 100 1.66 8.9 0 0 10

31.5* Whitby 15 min (dissipate) 20** 100 0.14 10.2 0 0 8


31.6 Whitby 30 min (dissipate) - 100 0.4 10.7 0 0 0

30.0 Whitby 3.5 hr (burn) 2 100 5 3.4 0 0 0

28.5 Whitby 25 minutes (dissipate) - 100 3.8 4 0 0 0

* Gas encountered during in-situ hydraulic conductivity (packer) test.

** Gas pressure inferred by the water pressure required to prevent backflow (during packer test).

Borehole abandoned before completion of packer tests due to continued presence of gas.


302

402

403

Gas Monitor Readings

205

206

206A

207

301

Borehole Elevation (m) Formation Time to Burn Off/Dissipate

Pressure Reading in

BOP line (psi)

Appendix C

Statement of Limitation

Coffey Geotechnics Pty Ltd ABN 93 056 929 483

As a client of Coffey you should know that site subsurface conditions cause more constructionproblems than any other factor. These notes have been prepared by Coffey to help youinterpret and understand the limitations of your report.

Your report is based on project specific criteria

Your report has been developed on the basis of yourunique project specific requirements as understoodby Coffey and applies only to the site investigated.Project criteria typically include the general nature ofthe project; its size and configuration; the location ofany structures on the site; other site improvements;the presence of underground utilities; and the additionalrisk imposed by scope-of-service limitations imposedby the client. Your report should not be used if thereare any changes to the project without first askingCoffey to assess how factors that changed subsequentto the date of the report affect the report'srecommendations. Coffey cannot accept responsibilityfor problems that may occur due to changed factorsif they are not consulted.

Subsurface conditions can change

Subsurface conditions are created by natural processesand the activity of man. For example, water levelscan vary with time, fill may be placed on a site andpollutants may migrate with time. Because a reportis based on conditions which existed at the time ofsubsurface exploration, decisions should not be basedon a report whose adequacy may have been affectedby time. Consult Coffey to be advised how time mayhave impacted on the project.

Interpretation of factual data

Site assessment identifies actual subsurface conditionsonly at those points where samples are taken andwhen they are taken. Data derived from literatureand external data source review, sampling and subsequent laboratory testing are interpreted bygeologists, engineers or scientists to provide anopinion about overall site conditions, their likelyimpact on the proposed development and recommendedactions. Actual conditions may differ from those inferredto exist, because no professional, no matter howqualified, can reveal what is hidden by

Your report will only givepreliminary recommendationsYour report is based on the assumption that thesite conditions as revealed through selectivepoint sampling are indicative of actual conditionsthroughout an area. This assumption cannot besubstantiated until project implementation hascommenced and therefore your report recommendationscan only be regarded as preliminary. Only Coffey,who prepared the report, is fully familiar with thebackground information needed to assess whetheror not the report's recommendations are valid andwhether or not changes should be considered asthe project develops. If another party undertakesthe implementation of the recommendations of thisreport there is a risk that the report will be misinterpretedand Coffey cannot be held responsible for suchmisinterpretation.

earth, rock and time. The actual interface betweenmaterials may be far more gradual or abrupt thanassumed based on the facts obtained. Nothing canbe done to change the actual site conditions whichexist, but steps can be taken to reduce the impact ofunexpected conditions. For this reason, ownersshould retain the services of Coffey through thedevelopment stage, to identify variances, conductadditional tests if required, and recommend solutionsto problems encountered on site.

Your report is prepared forspecific purposes and personsTo avoid misuse of the information contained in yourreport it is recommended that you confer with Coffeybefore passing your report on to another party whomay not be familiar with the background and thepurpose of the report. Your report should not beapplied to any project other than that originallyspecified at the time the report was issued.

Important information about your Coffey Report

* For further information on this aspect reference should bemade to "Guidelines for the Provision of Geotechnicalinformation in Construction Contracts" published by theInstitution of Engineers Australia, National headquarters,Canberra, 1987.

Interpretation by other design professionals

Costly problems can occur when other design professionals develop their plans based on misinterpretationsof a report. To help avoid misinterpretations, retainCoffey to work with other project design professionalswho are affected by the report. Have Coffey explainthe report implications to design professionals affectedby them and then review plans and specificationsproduced to see how they incorporate the reportfindings.

Data should not be separated from the report*

The report as a whole presents the findings of the siteassessment and the report should not be copied inpart or altered in any way.

Logs, figures, drawings, etc. are customarily includedin our reports and are developed by scientists,engineers or geologists based on their interpretationof field logs (assembled by field personnel) andlaboratory evaluation of field samples. These logs etc.should not under any circumstances be redrawn forinclusion in other documents or separated from thereport in any way.

Geoenvironmental concerns are not at issue

Your report is not likely to relate any findings,conclusions, or recommendations about the potentialfor hazardous materials existing at the site unlessspecifically required to do so by the client. Specialistequipment, techniques, and personnel are used toperform a geoenvironmental assessment.Contamination can create major health, safety andenvironmental risks. If you have no information aboutthe potential for your site to be contaminated or createan environmental hazard, you are advised to contactCoffey for information relating to geoenvironmentalissues.

Rely on Coffey for additional assistance

Coffey is familiar with a variety of techniques andapproaches that can be used to help reduce risks forall parties to a project, from design to construction. Itis common that not all approaches will be necessarilydealt with in your site assessment report due toconcepts proposed at that time. As the projectprogresses through design towards construction,speak with Coffey to develop alternative approachesto problems that may be of genuine benefit both intime and cost.

Responsibility

Reporting relies on interpretation of factual informationbased on judgement and opinion and has a level ofuncertainty attached to it, which is far less exact thanthe design disciplines. This has often resulted in claimsbeing lodged against consultants, which are unfounded.To help prevent this problem, a number of clauseshave been developed for use in contracts, reports andother documents. Responsibility clauses do not transferappropriate liabilities from Coffey to other parties butare included to identify where Coffey's responsibilitiesbegin and end. Their use is intended to help all partiesinvolved to recognise their individual responsibilities.Read all documents from Coffey closely and do nothesitate to ask any questions you may have.

Coffey Geotechnics Pty Ltd ABN 93 056 929 483

Important information about your Coffey Report

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