patersongroup Geotechnical Investigation Proposed Multi-Storey Building 235 King Edward Street Ottawa, Ontario Prepared For June 23, 2015

Transcription

1 Geotechnical Engineering patersongroup Environmental Engineering Hydrogeology Geological Engineering Materials Testing Building Science Proposed Multi-Storey Building 235 King Edward Street Ottawa, Ontario Archaeological Services Prepared For Manor Park Management Paterson Group Inc. Consulting Engineers 154 Colonnade Road South Ottawa, Ontario Canada K2E 7J5 Tel: (613) Fax: (613) June 23, 2015 Report PG2777-2

2 TABLE OF CONTENTS PAGE 1.0 INTRODUCTION PROPOSED PROJECT METHOD OF INVESTIGATION 3.1 Field Investigation Field Survey Laboratory Testing Analytical Testing OBSERVATIONS 4.1 Surface Conditions Subsurface Profile Groundwater DISCUSSION 5.1 Geotechnical Assessment Site Grading and Preparation Foundation Design Design for Earthquakes Basement Wall Basement Slab Rock Anchor Design Pavement Structure DESIGN AND CONSTRUCTION PRECAUTIONS 6.1 Foundation Drainage and Backfill Protection of Footings Against Frost Action Excavation Side Slopes Pipe Bedding and Backfill Groundwater Control Winter Construction Corrosion Potential and Sulphate RECOMMENDATIONS STATEMENT OF LIMITATIONS...24 June 23, 2015 Page i

3 APPENDICES Appendix 1 Appendix 2 Soil Profile and Test Data Sheets Symbols and Terms Analytical Testing Results Figure 1 - Key Plan Drawing PG Test Hole Location Plan June 23, 2015 Page ii

4 1.0 INTRODUCTION Paterson Group (Paterson) was commissioned by Manor Park Management to conduct a geotechnical investigation for a proposed multi-storey building to be located at 235 King Edward Street, in the City of Ottawa, Ontario (refer to Figure 1 - Key Plan in Appendix 2). The investigation objectives were to: determine the subsurface soil and groundwater conditions by means of boreholes. provide geotechnical recommendations for the design of the proposed development including construction considerations which may affect the design. The following report has been prepared specifically and solely for the aforementioned project which is described herein. This report contains our findings and includes geotechnical recommendations pertaining to the design and construction of the subject development as understood at the time of writing this report. 2.0 PROPOSED PROJECT It is understood that the proposed project is to consist of a six (6) to nine (9) storey building with two (2) levels of underground parking. Associated access lanes, and landscaped areas are also anticipated. June 23, 2015 Page 1

5 3.0 METHOD OF INVESTIGATION 3.1 Field Investigation Field Program The field program for the current investigation was conducted on May 12, At that time, two (2) boreholes were advanced to a maximum depth of 11.7 m depth. A previous investigation was conducted on September 26, 2012 and three (3) boreholes were advanced to a maximum depth of 11.2 m below the existing grade. The borehole locations were distributed in a manner to provide general coverage of the subject site. The locations of the boreholes are shown on Drawing PG Test Hole Location Plan included in Appendix 2. The boreholes were put down using truck-mounted power auger drill rig operated by a two-person crew. All fieldwork was conducted under the full-time supervision of our personnel under the direction of a senior engineer from our geotechnical department. The drilling procedures consisted of advancing each test hole to the required depths at the selected locations and sampling the overburden. Sampling and In Situ Testing Soil samples were recovered from auger flights or a 50 mm diameter split-spoon sample. The soil samples were classified on site, placed in sealed bags and transported to our laboratory. The depths at which the auger and split-spoon samples were recovered from the boreholes are shown as AU and SS, respectively, on the Soil Profile and Test Data sheets. The Standard Penetration Test (SPT) was conducted in conjunction with the recovery of the split-spoon samples. The SPT results are recorded as N values on the Soil Profile and Test Data sheets. The N value is the number of blows required to drive the split-spoon 300 mm into the soil after a 150 mm initial penetration using a 63.5 kg hammer falling from a height of 760 mm. Overburden thickness was evaluated during the course of the investigation by a dynamic cone penetration test (DCPT) at BH 2 and BH The DCPT consists of driving a steel drill rod, equipped with a 50 mm diameter cone tip, using a 63.5 kg hammer falling from a height of 760 mm. The number of blows required to drive the cone into the soil is recorded every 300 mm increment. Undrained shear strength tests were completed in cohesive soils with a shear vane apparatus. June 23, 2015 Page 2

6 The subsurface conditions observed in the test holes were recorded in detail in the field. The soil profiles are logged on the Soil Profile and Test Data sheets in Appendix 1. Groundwater Flexible polyethylene standpipes were installed in all boreholes to permit monitoring and sampling of the groundwater subsequent to the completion of the geotechnical drilling program. 3.2 Field Survey The borehole locations were selected and determined in the field by Paterson personnel to provide general coverage of the subject site. Ground surface elevations at borehole locations are referenced to a temporary benchmark (TBM), consisting of the top spindle of the fire hydrant located on the south side of St. Patrick Street, east of the subject site. An assumed elevation of 100 m was assigned to the TBM. The location and ground surface elevation at each borehole location are presented on Drawing PG Test Hole Location Plan in Appendix Laboratory Testing Soil samples were recovered from the subject site and visually examined in our laboratory to review the field results. Sample Storage All samples will be stored in the laboratory for a period of one month after issuance of this report. They will then be discarded unless we are otherwise directed. 3.4 Analytical Testing One soil sample was submitted for analytical testing to assess the potential for exposed ferrous metals and sulphate attacks against subsurface concrete structures. The sample was analyzed to determine the concentration of sulphate and chloride along with resistivity and ph. The laboratory test results are shown in Appendix 1 and the results are discussed in Subsection 6.7. June 23, 2015 Page 3

7 4.0 OBSERVATIONS 4.1 Surface Conditions Currently, the majority of the subject site is a gravel parking lot with two residential buildings to be demolished within the south portion of the site. The subject site is bordered by St. Patrick Street to the north, King Edward Street to the West and Murray Street to the south and east. The site is generally flat and at grade with St. Patrick Street and King Edward Street. 4.2 Subsurface Profile Generally, the subsurface profile consists of a crushed stone fill or an asphalt pavement structure underlain by a silty sand fill layer. The fill layers are overlying a native brown to grey, stiff to very stiff silty clay. Practical refusal to DCPT was encountered at a 11.2 and 11.7 m depth in BH 2 and BH 1-15, respectively. Based on available geological mapping, bedrock in the area of the subject site consists of an interbedded limestone and shale from the Veralum Formation. The overburden drift thickness is estimated to be between 5 and 10 m depth. 4.3 Groundwater The groundwater level readings measured at the piezometer installed at the borehole locations are presented in Table 1. The long-term groundwater table can also be estimated based on moisture levels and colour of the recovered soil samples. Based on these observations, the long-term groundwater level is expected at a depth ranging from 5 to 7 m below the existing grade. The groundwater is subject to seasonal fluctuations and therefore, groundwater could vary at the time of construction. June 23, 2015 Page 4

8 Table 1 - Groundwater Elevations Borehole Number Ground Elevation (m) Groundwater Levels Depth (m) Elevation (m) Recording Date Groundwater Elevations: PG (Current) BH June 11, 2015 BH June 11, 2015 Groundwater Elevations: PG BH October 19, 2012 BH October 19, 2012 BH October 19, 2012 Groundwater Elevations: G BH January 24, 2000 BH January 24, 2000 Note: Ground surface elevations at borehole locations are referenced to a temporary benchmark (TBM), consisting of the top spindle of the fire hydrant located on the south side of St. Patrick Street, east of the subject site. An assumed elevation of 100 m was assigned to the TBM. June 23, 2015 Page 5

9 5.0 DISCUSSION 5.1 Geotechnical Assessment From a geotechnical perspective, the subject site is satisfactory for the proposed development. The proposed building could be founded on conventional footings placed on an undisturbed, stiff silty clay provided the bearing resistance values can accommodate the proposed building loads. However, based on the proposed founding depth of approximately 7 to 8 m below the existing grade and anticipated building loads, a raft foundation should be considered for the proposed structure. Consideration may also be given to adding a third level of underground parking and extending the footings to the underlying inferred bedrock at a depth of 11 to 12 m below the existing grade. The above and other considerations are discussed in the following paragraphs. 5.2 Site Grading and Preparation Stripping Depth Based on the anticipated excavation depth, all topsoil and fill materials will be removed from within the perimeter of the proposed building. Protective Mud Slab The excavation bottom will consist of a silty clay deposit and should be protected from disturbance due to worker traffic. It is recommend that a minimum 50 mm thick lean concrete mud slab should be poured on the undisturbed clay surface once exposed. The lean concrete can consist of minimum 15 MPa compressive strength concrete. Fill Placement Fill placed for grading beneath the proposed building, unless otherwise specified, should consist of clean imported granular fill, such as Ontario Provincial Standard Specifications (OPSS) Granular A or Granular B Type II. The fill should be tested and approved prior to delivery. The granular material should be placed in maximum 300 mm thick lifts and compacted using suitable compaction equipment for the lift thickness. Fill placed beneath the building should be compacted to at least 98% of the Standard Proctor Maximum Dry Density. June 23, 2015 Page 6

10 Non-specified existing fill along with site-excavated soil can be placed as general landscaping fill where settlement of the ground surface is of minor concern. These materials should be spread in thin lifts and compacted by the tracks of the spreading equipment to minimize voids. If these materials are to be placed under the subgrade level for areas to be paved, the material should be compacted in thin lifts to a minimum density of 95% of the SPMDD. Non-specified existing fill and site-excavated soils are not suitable for placement as backfill against foundation walls unless a composite drainage blanket connected to a perimeter drainage system is provided. 5.3 Foundation Design Bearing Resistance Values (2 Levels of Underground Parking) Footings placed on an undisturbed stiff silty clay bearing surface can be designed using a bearing resistance value at serviceability limit states (SLS) of 100 kpa and a factored bearing resistance value at ultimate limit states (ULS) of 150 kpa. Footings designed using the above-noted bearing resistance value at SLS will be subjected to potential post-construction total and differential settlements of 25 and 20 mm, respectively. An undisturbed soil bearing surface consists of a surface from which all topsoil and deleterious materials, such as loose, frozen or disturbed soil, whether in situ or not, have been removed, in the dry, prior to the placement of concrete for footings. Lean Concrete Filled Trenches (2 Levels of Underground Parking) For improving the bearing resistance values while remaining with two levels of underground parking, consideration should be given to excavating vertical trenches to expose the underlying bedrock surface and backfilling with lean concrete (20 MPa 28- day compressive strength). Typically, the excavation side walls will be used as the form to support the concrete. The additional width of the concrete poured against an undisturbed trench sidewall will suffice in providing a direct transfer of the footing load to the underlying bedrock. The effectiveness of this operation will depend on the ability of maintaining vertical trenches until the lean concrete can be poured. It is suggested that once the bottom of the excavation is exposed, a test pit should be undertaken to assess the water infiltration issues and stability of the excavation sidewalls extending to the bedrock surface. June 23, 2015 Page 7

11 The trench excavation should be at least 300 mm wider than all sides of the footing at the base of the excavation. The excavation bottom should be relatively clean using the hydraulic shovel only (workers will not be permitted in the excavation below a 1.5 m depth). Once approved by the geotechnical engineer, lean concrete can be poured up to the proposed founding elevation. Footings placed on lean concrete filled trenches extending to the limestone bedrock surface can be designed using a factored bearing resistance value at ultimate limit states (ULS) of 3,000 kpa incorporating a geotechnical resistance factor of 0.5 was applied to the bearing resistance value at ULS and a bearing resistance value at serviceability limit states (SLS) of 1,500 kpa. Bearing Resistance Values (3 Levels of Underground Parking) Footings placed on a clean surface sounded limestone bedrock surface can be designed using a factored bearing resistance value at ultimate limit states (ULS) of 3,000 kpa incorporating a geotechnical resistance factor of 0.5 was applied to the bearing resistance value at ULS and a bearing resistance value at serviceability limit states (SLS) of 1,500 kpa. A clean, surface-sounded bedrock bearing surface should be free of loose materials, and have no near surface seams, voids, fissures or open joints which can be detected from surface sounding with a rock hammer. Lateral Support The bearing medium under footing-supported structures is required to be provided with adequate lateral support with respect to excavations and different foundation levels. Adequate lateral support is provided to an engineered fill or stiff silty clay bearing medium when a plane extending, a minimum of 1.5H:1V, from the bottom edge of the footing to the founding soil/engineered fill. Raft Foundation Consideration should be given to a raft foundation to found the proposed structure. June 23, 2015 Page 8

12 The amount of settlement of the raft slab will be dependent on the sustained raft contact pressure. A bearing resistance value at serviceability limit states (SLS) (contact pressure) of 100 kpa could be used. The loading conditions for the contact pressure are based on sustained loads, that are generally 100% dead load and 50% live load. The factored bearing resistance at ultimate limit states (ULS) is calculated to be 200 kpa. A geotechnical resistance factor of 0.5 was applied to the bearing resistance value at ULS. The modulus of subgrade reaction was calculated to be 5 MPa/m for a contact pressure of 100 kpa. The design of the raft foundation should consider the relative stiffness of the reinforced concrete slab and the supporting bearing medium. A common method of modelling the soil structure interaction should consider the bearing medium to be elastic and to assign a subgrade modulus. However, sensitive silty clay is not elastic and limits have to be placed on the stress ranges of a particular modulus. This value can be re-evaluated once detail of the structural design becomes available. Based on the above assumptions for the raft foundation, the proposed structure could be designed with the above parameters and a total and differential settlement of 25 and 15 mm, respectively. The base of the raft foundation (approximately 0.8 to 1 m thick) is to be located at a depth of approximately 7 m below the current ground surface. The long-term groundwater level (LGWL) is estimated to be at a depth of 5 to 7 m below the existing grade. The raft slab is impervious and the basement walls will be provided with a perimeter foundation drainage system. Deep Foundation Deep foundation methods could be considered for the proposed structure. Concrete filled steel pipe piles to refusal on a bedrock surface are the most common deep foundation option constructed in the Ottawa area. An alternative would be the use of augered caissons socketed into bedrock. If a deep foundation option is considered, more information can be provided upon request. Caissons should bearing surface should be free of any loose material and inspected by competent geotechnical personnel prior to pouring concrete. June 23, 2015 Page 9

13 5.4 Design for Earthquakes The site class for seismic site response is a Class D for the footings or raft foundation founded on the silty clay deposit. A Class A can be given for the footings extending to bedrock, however, the higher seismic site classification must be confirmed by site specific shear wave velocity test. The soils underlying the subject site are not susceptible to liquefaction. Reference should be made to the latest revision of the Ontario Building Code for a full discussion of the earthquake design requirements. 5.5 Basement Wall There are several applicable combinations of backfill materials and retaining soils for the basement walls of the subject structure. However, the conditions should be designed by assuming the retaining soil consists of a material with an angle of internal 3 friction of 30 degrees and a dry unit weight of 20 kn/m. The total earth pressure (P AE) includes both the static earth pressure component (P o) and the seismic component (ÄP ). AE Static Earth Pressures The static horizontal earth pressure (P o) should be calculated by a triangular earth pressure distribution equal to K ã H where: o K o = at-rest earth pressure coefficient of the applicable retained soil, 0.5 ã = unit weight of the fill of the applicable retained soil (kn/m 3 ) H = height of the wall (m) June 23, 2015 Page 10

14 Seismic Earth Pressures The seismic earth pressure (ÄP AE) should be calculated using the earth pressure 2 distribution equal to 0.375a ãh /g where: c a c = (1.45-a max/g)a max ã = unit weight of fill of the applicable retained soil (kn/m 3 ) H = height of the wall (m) g = gravity, 9.81 m/s 2 The peak ground acceleration, (a max), for the Ottawa area is 0.32g according to OBC Note that the vertical seismic coefficient is assumed to be zero. The total earth pressure (P the wall. Where: AE ) is considered to act at a height, h, (m) from the base of h = {P o(h/3)+äp AE(0.6H)}/PAE The earth pressures calculated are unfactored. For the ULS case, the earth pressure loads should be factored as live loads, as per OBC Basement Slab It is expected that the lower basement slab will consist of footings or a raft foundation for the parking garage for the multi-storey building. It is expected that the basement area will be mostly parking and that a concrete slab with a subfloor granular layer will be incorporated in the design to accommodate services. A rigid pavement structure is presented in Subsection 5.8. The thickness of the granular subfloor layer will be dependent on what services are incorporated in the design. It is also expected that a sump pit will be incorporated to drain any water which enters the granular layer via a breach in the raft slab. A concrete mud slab should be placed to protect the native soil from worker traffic and equipment before pouring the raft slab. June 23, 2015 Page 11

15 5.7 Rock Anchor Design The geotechnical design of grouted rock anchors in limestone bedrock is based upon two possible failure modes. The rock anchor can fail either by shear failure along the grout/rock interface or by pullout at 60 to 90 degree cone of rock with the apex of the cone near the middle of the bonded length of the anchor. Interaction may develop between the failure cones of anchors that are relatively close to one another resulting in a total group capacity smaller than the sum of the individual anchor load capacity. A third failure mode of shear failure along the grout/steel interface should be reviewed by a qualified structural engineer to ensure all typical failure modes have been reviewed. Typical rock anchor suppliers, such as Dywidag Systems International (DSI Canada) or Williams Form Engineering, have qualified personnel on staff to recommend appropriate rock anchor size and materials. The centre to centre spacing between bond lengths should be at least 1.2 m or a minimum of four times the anchor hole diameter to ensure the group influence effects are minimized. Anchors in close proximity to each other are recommended to be grouted at the same time to ensure any fractures or voids are completely in-filled and grout fluid does not flow from one hole to an adjacent empty one. Anchors can be of the passive or the post-tensioned type, depending on whether the anchor tendon is provided with post-tensioned load or not, prior to servicing. To resist seismic uplift pressures, a passive rock anchor system is adequate. However, a post-tensioned anchor will absorb the uplift load pressure with less deflection than a passive anchor. Regardless of whether an anchor is of the passive or the post tensioned type, it is recommended that the anchor is provided with a fixed anchor length at the anchor base, which will provide the anchor capacity, and an free anchor length between the rock surface and the top of the bonded length. As the depth at which the apex of the shear failure cone develops midway along the bonded length, a fully bonded anchor would tend to have a much shallower cone, and therefore less geotechnical resistance, than one where the bonded length is limited to the bottom part of the overall anchor. Permanent anchors should be provided with corrosion protection. As a minimum, this requires that the entire drill hole be filled with cementitious grout. The free anchor length is provided by installing a sleeve to act as a bond break, with the sleeve filled with grout. Double corrosion protection can be provided with factory assembled systems, such as those available from Dywidag Systems International or Williams Form Engineering Corp. June 23, 2015 Page 12

16 Grout to Rock Bond Generally, the unconfined compressive strength of limestone ranges between 50 and 80 MPa, which is stronger than most routine grouts. A factored tensile grout to rock bond resistance value at ULS of 1.0 MPa, incorporating a resistance factor of 0.3, should be provided. A minimum grout strength of 40 MPa is recommended. Rock Cone Uplift The rock anchor capacity depends on the dimensions of the rock anchors and the anchorage system configuration. Based on bedrock information, a Rock Mass Rating (RMR) of 44 was assigned to the bedrock, and Hoek and Brown parameters (m and s) were taken as and , respectively. Recommended Grouted Rock Anchor Lengths Parameters used to calculate grouted rock anchor lengths are provided in Table 2. Table 2 - Parameters used in Rock Anchor Review Grout to Rock Bond Strength - Factored at ULS Compressive Strength - Grout Rock Mass Rating (RMR) - Good quality Limestone Hoek and Brown parameters Unconfined compressive strength - Limestone 1.0 MPa 40 MPa 44 m=0.128 and s= MPa Unit weight - Submerged Bedrock 15 kn/m 3 Apex angle of failure cone Apex of failure cone 60 o mid-point of fixed anchor length The fixed anchor length will depend on the diameter of the drill holes. Recommended anchor lengths are provided in Table 3. The factored tensile resistance values provided are based on a single anchor with no group influence effects. June 23, 2015 Page 13

17 Table 3 - Recommended Rock Anchor Lengths - Grouted Rock Anchor Diameter of Drill Hole (mm) Bonded Length Anchor Lengths (m) Unbonded Length Total Length Factored Tensile Resistance (kn) Other considerations It is recommended that the anchor drill hole diameter be within 1.5 to 2 times the rock anchor tendon diameter. The anchor drill holes should be inspected by geotechnical personnel and should be flushed clean prior to grouting. A tremie pipe is recommended to place grout from the bottom to top of the anchor holes. The geotechnical capacity of each rock anchor should be proof tested at the time of construction. More information on test procedures can be provided upon request. 5.8 Pavement Structure The proposed parking level slabs will be considered a rigid pavement structure. The following rigid pavement structure is recommended to support car parking only. Table 4 - Recommended Rigid Pavement Structure - Car Only Parking Areas Thickness (mm) Material Description 125 Wear Course - Concrete slab 200 BASE - 20 mm clear stone SUBGRADE - Concrete transfer slab June 23, 2015 Page 14

18 Asphalt pavement is not anticipated to be required at the subject site. However, should pavement be reconsidered for the project, the recommended pavement structures shown in Tables 5 and 6 would be applicable. Table 5 - Recommended Flexible Pavement Structure - Car Only Parking Areas Thickness (mm) Material Description 50 Wear Course - HL-3 or Superpave 12.5 Asphaltic Concrete 150 BASE - OPSS Granular A Crushed Stone 300 SUBBASE - OPSS Granular B Type II SUBGRADE - In situ soil, or OPSS Granular B Type I or II material placed over in situ soil Table 6 - Recommended Flexible Pavement Structure Access Ramp/Lanes and Heavy Truck Parking Areas Thickness (mm) Material Description 40 Wear Course - HL-3 or Superpave 12.5 Asphaltic Concrete 50 Binder Course - HL-8 or Superpave 19.0 Asphaltic Concrete 150 BASE - OPSS Granular A Crushed Stone 400 SUBBASE - OPSS Granular B Type II SUBGRADE - In situ soil, or OPSS Granular B Type I or II material placed over in situ soil Minimum Performance Graded (PG) asphalt cement should be used for this project. If soft spots develop in the subgrade during compaction or due to construction traffic, the affected areas should be excavated and replaced with OPSS Granular B Type II material. The pavement granular base and subbase should be placed in maximum 300 mm thick lifts and compacted to a minimum of 98% of the SPMDD using suitable compaction equipment. June 23, 2015 Page 15

19 Pavement Structure Drainage Satisfactory performance of the pavement structure is largely dependent on keeping the contact zone between the subgrade material and the base stone in a dry condition. Failure to provide adequate drainage under conditions of heavy wheel loading can result in the fine subgrade soil being pumped into the voids in the stone subbase, thereby reducing the load bearing capacity. Due to the impervious nature of the subgrade materials consideration should be given to installing subdrains during the pavement construction. These drains should extend longitudinally when placed along a curb. The clear stone surrounding the drainage lines or the pipe, should be wrapped with filter cloth. The subdrain inverts should be approximately 300 mm below subgrade level. The subgrade surface should be shaped to promote water flow to the drainage lines. June 23, 2015 Page 16

20 6.0 DESIGN AND CONSTRUCTION PRECAUTIONS 6.1 Foundation Drainage and Backfill Foundation Drainage It is understood that the building foundation walls will be placed in close proximity to all the boundaries. It is expected that insufficient room will be available for most of the exterior backfill along these walls and, therefore, the foundation wall will be blind poured against a drainage system placed against the shoring face. A waterproofing membrane will be required to lessen the effect of water infiltration for the basement levels starting at 4 or 5 m below finished grade. The waterproofing membrane can be placed over a suitably prepared surface and should extend to the footing founding depth. The membrane should be placed horizontally at least 1 m beneath the footings to ensure a suitable seal at that location. It is recommended that the composite drainage system (such as Miradrain G100N or equivalent) extend down to the footing level. The purpose of the composite drainage system is to relieve any breaches in the waterproofing membrane. It is recommended that 150 mm diameter sleeves at 3 m centres be cast in the footing or at the foundation wall/footing interface to allow the infiltration of water to flow to an interior perimeter drainage pipe. The perimeter drainage pipe should direct water to sump pit(s) within the lower basement area. Underfloor Drainage Underfloor drainage will be required to control water infiltration due to groundwater infiltration at the proposed founding elevation. For design purposes, we recommend that 150 mm in diameter perforated pipes be placed at 6 m centres. The spacing of the underfloor drainage system should be confirmed at the time of completing the excavation when water infiltration can be better assessed. Adverse Effects of Dewatering on Adjacent Properties Since the proposed development will be founded below the long term groundwater level, a waterproofing membrane was recommended to lessen the effects of water infiltration. Any dewatering of the site will be minor and should have no adverse effects to the surrounding buildings or properties. June 23, 2015 Page 17

21 Foundation Backfill Where space is available for conventional wall construction, backfill against the exterior sides of the foundation walls should consist of free-draining non frost susceptible granular materials. Imported granular materials, such as clean sand or OPSS Granular B Type I granular material, should be used for this purpose. 6.2 Protection of Footings Against Frost Action Perimeter footings, of heated structures are required to be insulated against the deleterious effect of frost action. A minimum of 1.5 m thick soil cover (or equivalent) should be provided. A minimum of 2.1 m thick soil cover (or equivalent) should be provided for other exterior unheated footings. 6.3 Excavation Side Slopes The side slopes of excavations in the soil and fill overburden materials should either be excavated at acceptable slopes or should be retained by shoring systems from the beginning of the excavation until the structure is backfilled. It is assumed that sufficient room will be available for the greater part of the excavation to be constructed by opencut methods (i.e. unsupported excavations). The excavation side slopes above the groundwater level extending to a maximum depth of 3 m should be excavated at 1H:1V or flatter. The flatter slope is required for excavation below groundwater level. The subsurface soils are considered to be a Type 2 and 3 soil according to the Occupational Health and Safety Act and Regulations for Construction Projects. Excavated soil should not be stockpiled directly at the top of excavations and heavy equipment should be kept away from the excavation sides. Slopes in excess of 3 m in height should be periodically inspected by the geotechnical consultant in order to detect if the slopes are exhibiting signs of distress. A trench box is recommended to protect personnel working in trenches with steep or vertical sides. Services are expected to be installed by cut and cover methods and excavations will not be left open for extended periods of time. June 23, 2015 Page 18

22 Temporary Shoring Temporary shoring may be required for the overburden soil to complete the required excavations where insufficient room is available for open cut methods. The shoring requirements will depend on the depth of the excavation, the proximity of the adjacent buildings and underground structures and the elevation of the adjacent building foundations and underground services. The temporary system may consist of soldier pile and lagging system or interlocking steel sheet piling. Any additional loading due to street traffic, construction equipment, adjacent structures and facilities, etc., should be added to the earth pressures described below. These systems can be cantilevered, anchored or braced. Generally, it is expected that the shoring systems will be provided with tie-back rock anchors to ensure their stability. It is further recommended that the toe of the shoring be adequately supported to resist toe failure, if required, by means of rock bolts or extending the piles into the bedrock through pre-augered holes if a soldier pile and lagging system is used. The earth pressures acting on the shoring system may be calculated using the following parameters. Table 7 - Soil Parameters Parameters Values Active Earth Pressure Coefficient (K a) 0.33 Passive Earth Pressure Coefficient (K p) 3 At-Rest Earth Pressure Coefficient (K o) Dry Unit Weight (ã), kn/m 20 3 Effective Unit Weight (ã), kn/m 13 The active earth pressure should be calculated where wall movements are permissible while the at-rest pressure should be calculated if no movement is permissible. The dry unit weight should be used above the groundwater level while the effective unit weight should be used below the groundwater level. The hydrostatic groundwater pressure should be added to the earth pressure distribution wherever the effective unit weights are used for earth pressure calculations. If the groundwater level is lowered, the dry unit weight for the soil should be used full weight, with no hydrostatic groundwater pressure component. For design purposes, the minimum factor of safety of 1.5 should be calculated. June 23, 2015 Page 19

23 6.4 Pipe Bedding and Backfill The pipe bedding for sewer and water pipes should consist of at least 150 mm of OPSS Granular A material. The material should be placed in a maximum lift thickness of 300 mm and compacted to a minimum of 95% of the SPMDD. The bedding material should extend at least to the spring line of the pipe. Where hard surface areas are considered above the trench backfill, the trench backfill material within the frost zone (about 1.8 m below finished grade) should match the soils exposed at the trench walls to minimize differential frost heaving. The trench backfill should be placed in maximum 300 mm thick loose lifts and compacted to a minimum of 95% of the SPMDD. Clay Seals Trenches located below the groundwater table should be provided with clay seals to reduce long-term groundwater lowering. The clay seals should be as per Standard Drawing No. S8 of the Department of Public Works and Services, Infrastructure Services Branch of the City of Ottawa. The seals should be at least 1.5 m long (in the trench direction), as compared to the 1 m minimum in the detail, and should extend from trench wall to trench wall. Generally, the seals should extend from the frost line and fully penetrate the bedding, subbedding and cover material. The barriers should consist of relatively dry and compactable stiff silty clay placed in maximum 225 mm thick loose layers and compacted to a minimum of 95% of the material s SPMDD. The clay seals should be placed at the site boundaries and at strategic locations at no more than 60 m intervals in the service trenches. 6.5 Groundwater Control It is anticipated that groundwater infiltration into the excavations should be low to moderate and controllable using open sumps. Pumping from open sumps should be sufficient to control the groundwater influx through the sides of shallow excavations. The contractor should be prepared to direct water away from all bearing surfaces and subgrades, regardless of the source, to prevent disturbance to the founding medium. A temporary MOE permit to take water (PTTW) may be required for this project if more than 50,000 L/day is to be pumped during the construction phase. At least 4 to 5 months should be allowed for completion of the application and issuance of the permit by the MOE. June 23, 2015 Page 20

24 6.6 Winter Construction Precautions must be taken if winter construction is considered for this project. The subsoil conditions at this site mostly consist of frost susceptible materials. In presence of water and freezing conditions ice could form within the soil mass. Heaving and settlement upon thawing could occur. In the event of construction during below zero temperatures, the founding stratum should be protected from freezing temperatures by the use of straw, propane heaters and tarpaulins or other suitable means. In this regard, the base of the excavations should be insulated from sub-zero temperatures immediately upon exposure and until such time as heat is adequately supplied to the building and the footings are protected with sufficient soil cover to prevent freezing at founding level. The trench excavations should be carried out in a manner to avoid the introduction of frozen materials, snow or ice into the trenches. Precaution must be taken where excavations are carried in proximity of existing structures which may be adversely affected due to the freezing conditions. In particular, it should be recognized that where a shoring system is used, the soil behind the shoring system will be subjected to freezing conditions and could result in heaving of the structure(s) placed within or above frozen soil. Provisions should be made in the contract document to protect the walls of the excavations from freezing, if applicable. In the event of construction during below zero temperatures, the founding stratum should be protected from freezing temperatures by the use of straw, propane heaters and tarpaulins or other suitable means. The base of the excavations should be insulated from sub-zero temperatures immediately upon exposure and until such time as heat is adequately supplied to the building and the footings are protected with sufficient soil cover to prevent freezing at founding level. Trench excavations and pavement construction are difficult activities to complete during freezing conditions without introducing frost in the subgrade or in the excavation walls and bottoms. Precautions should be taken if such activities are to be completed during freezing conditions. June 23, 2015 Page 21

25 6.7 Corrosion Potential and Sulphate The analytical testing results are presented in Table 8 along with industry standards for the applicable threshold values. These results are indicative that Type 10 Portland cement (Type GU, or normal cement) would be appropriate for this site. Table 8 - Corrosion Potential Parameter Laboratory Results Threshold Commentary BH 3 - SS5 Chloride 604 ìg/g Chloride content less than 400 mg/g Negligible concern ph 7.57 ph value less than 5.0 Neutral Soil Resistivity 11.4 ohm.m Resistivity greater than 1,500 ohm.cm Sulphate 639 ìg/g Sulphate value greater than 1 mg/g Moderate Corrosion Potential Negligible Concern June 23, 2015 Page 22

26 7.0 RECOMMENDATIONS A materials testing and observation services program is a requirement for the provided foundation design data to be applicable. The following aspects of the program should be performed by the geotechnical consultant: Observation of all bearing surfaces prior to the placement of concrete. Inspection of all below grade water proofing and foundation drainage systems. Sampling and testing of the concrete and fill materials used. Periodic observation of the condition of unsupported excavation side slopes in excess of 3 m in height, if applicable. Observation of all subgrades prior to backfilling. Field density tests to determine the level of compaction achieved. Sampling and testing of the bituminous concrete including mix design reviews. A report confirming the above items have been completed in general accordance with our recommendations could be issued following the completion of a satisfactory materials testing and observation program by the geotechnical consultant. June 23, 2015 Page 23

27 8.0 STATEMENT OF LIMITATIONS The recommendations provided in this report are in accordance with our present understanding of the project. We request permission to review our recommendations when the grading plan, drawings and specifications are completed. A geotechnical investigation of this nature is a limited sampling of a site. The recommendations are based on information gathered at the specific test locations and can only be extrapolated to an undefined limited area around the test locations. Should any conditions at the site be encountered which differ from those at the test locations, we request notification immediately in order to permit reassessment of our recommendations. The present report applies only to the project described in this document. Use of this report for purposes other than those described herein or by person(s) other than Manor Park Management, or their agent(s) is not authorized without review by Paterson Group for the applicability of our recommendations to the altered use of the report. Paterson Group Inc. Faisal I. Abou-Seido, P.Eng. David J. Gilbert, P.Eng. Report Distribution: Manor Park Management. (3 copies) Paterson Group (1 copy) June 23, 2015 Page 24

28 APPENDIX 1 SOIL PROFILE AND TEST DATA SHEETS SYMBOLS AND TERMS ANALYTICAL TESTING RESULTS

29 154 Colonnade Road South, Ottawa, Ontario K2E 7J5 DATUM REMARKS BORINGS BY Consulting Engineers Prop. Multi-Storey Hotel King Edward Ave. Ottawa, Ontario TBM - Top spindle of fire hydrant located on the south side of St. Patrick Street, east of subject site. An arbitrary elevation of m was assigned to the TBM. CME 55 Power Auger DATE SOIL PROFILE AND TEST DATA May 12, 2015 FILE NO. HOLE NO. PG2777 BH 1-15 SOIL DESCRIPTION GROUND SURFACE Asphaltic concrete FILL: Crushed Stone FILL: Brown silty sand with gravel and cobbles, trace glass, brick, mortar, trace clay STRATA PLOT TYPE G SS SAMPLE NUMBER 2 1 % RECOVERY 4 N VALUE or RQD 2 DEPTH (m) 0 1 ELEV. (m) Pen. Resist. Blows/0.3m 50 mm Dia. Cone Water Content % Piezometer Construction SS SS Stiff to very stiff, light brown SILTY CLAY stiff and grey by 5.5m depth Dynamic Cone Pentration Test commenced at 9.14m depth End of Borehole Practical DCPT refusal at 11.71m depth 5.05m-June 11, 2015) Shear Strength (kpa) Undisturbed Remoulded

30 Engineers 154 Colonnade Road South, Ottawa, Ontario K2E 7J5 DATUM REMARKS BORINGS BY Consulting Prop. Multi-Storey Hotel King Edward Ave. Ottawa, Ontario TBM - Top spindle of fire hydrant located on the south side of St. Patrick Street, east of subject site. An arbitrary elevation of m was assigned to the TBM. CME 55 Power Auger DATE SOIL PROFILE AND TEST DATA May 12, 2015 FILE NO. HOLE NO. PG2777 BH 2-15 SOIL DESCRIPTION GROUND SURFACE TOPSOIL 0.25 STRATA PLOT TYPE SAMPLE NUMBER % RECOVERY N VALUE or RQD DEPTH (m) 0 ELEV. (m) Pen. Resist. Blows/0.3m 50 mm Dia. Cone Water Content % Piezometer Construction Stiff, brown SILTY CLAY with sand SS SS SS Stiff to very stiff, grey SILTY CLAY SS Grey CLAYEY SILT Grey SILT with clay, trace sand End of Borehole SS m-June 11, 2015) Shear Strength (kpa) Undisturbed Remoulded

31

32

33

34

35

36

37 SYMBOLS AND TERMS SOIL DESCRIPTION Behavioural properties, such as structure and strength, take precedence over particle gradation in describing soils. Terminology describing soil structure are as follows: Desiccated - having visible signs of weathering by oxidation of clay minerals, shrinkage cracks, etc. Fissured - having cracks, and hence a blocky structure. Varved - composed of regular alternating layers of silt and clay. Stratified - composed of alternating layers of different soil types, e.g. silt and sand or silt and clay. Well-Graded - Having wide range in grain sizes and substantial amounts of all intermediate particle sizes (see Grain Size Distribution). Uniformly-Graded - Predominantly of one grain size (see Grain Size Distribution). The standard terminology to describe the strength of cohesionless soils is the relative density, usually inferred from the results of the Standard Penetration Test (SPT) N value. The SPT N value is the number of blows of a 63.5 kg hammer, falling 760 mm, required to drive a 51 mm O.D. split spoon sampler 300 mm into the soil after an initial penetration of 150 mm. Relative Density N Value Relative Density % Very Loose <4 <15 Loose Compact Dense Very Dense >50 >85 The standard terminology to describe the strength of cohesive soils is the consistency, which is based on the undisturbed undrained shear strength as measured by the in situ or laboratory vane tests, penetrometer tests, unconfined compression tests, or occasionally by Standard Penetration Tests. Consistency Undrained Shear Strength (kpa) N Value Very Soft <12 <2 Soft Firm Stiff Very Stiff Hard >200 >30

38 SYMBOLS AND TERMS (continued) SOIL DESCRIPTION (continued) Cohesive soils can also be classified according to their sensitivity. The sensitivity is the ratio between the undisturbed undrained shear strength and the remoulded undrained shear strength of the soil. Terminology used for describing soil strata based upon texture, or the proportion of individual particle sizes present is provided on the Textural Soil Classification Chart at the end of this information package. ROCK DESCRIPTION The structural description of the bedrock mass is based on the Rock Quality Designation (RQD). The RQD classification is based on a modified core recovery percentage in which all pieces of sound core over 100 mm long are counted as recovery. The smaller pieces are considered to be a result of closelyspaced discontinuities (resulting from shearing, jointing, faulting, or weathering) in the rock mass and are not counted. RQD is ideally determined from NXL size core. However, it can be used on smaller core sizes, such as BX, if the bulk of the fractures caused by drilling stresses (called mechanical breaks ) are easily distinguishable from the normal in situ fractures. RQD % ROCK QUALITY Excellent, intact, very sound Good, massive, moderately jointed or sound Fair, blocky and seamy, fractured Poor, shattered and very seamy or blocky, severely fractured 0-25 Very poor, crushed, very severely fractured SAMPLE TYPES SS - Split spoon sample (obtained in conjunction with the performing of the Standard Penetration Test (SPT)) TW - Thin wall tube or Shelby tube PS - Piston sample AU - Auger sample or bulk sample WS - Wash sample RC - Rock core sample (Core bit size AXT, BXL, etc.). Rock core samples are obtained with the use of standard diamond drilling bits.

39 SYMBOLS AND TERMS (continued) GRAIN SIZE DISTRIBUTION MC% - Natural moisture content or water content of sample, % LL - Liquid Limit, % (water content above which soil behaves as a liquid) PL - Plastic limit, % (water content above which soil behaves plastically) PI - Plasticity index, % (difference between LL and PL) Dxx - Grain size which xx% of the soil, by weight, is of finer grain sizes These grain size descriptions are not used below mm grain size D10 - Grain size at which 10% of the soil is finer (effective grain size) D60 - Grain size at which 60% of the soil is finer Cc - Concavity coefficient = (D30) 2 / (D10 x D60) Cu - Uniformity coefficient = D60 / D10 Cc and Cu are used to assess the grading of sands and gravels: Well-graded gravels have: 1 < Cc < 3 and Cu > 4 Well-graded sands have: 1 < Cc < 3 and Cu > 6 Sands and gravels not meeting the above requirements are poorly-graded or uniformly-graded. Cc and Cu are not applicable for the description of soils with more than 10% silt and clay (more than 10% finer than mm or the #200 sieve) CONSOLIDATION TEST p o - Present effective overburden pressure at sample depth p c - Preconsolidation pressure of (maximum past pressure on) sample Ccr - Recompression index (in effect at pressures below p c ) Cc - Compression index (in effect at pressures above p c ) OC Ratio Overconsolidaton ratio = p c / p o Void Ratio Initial sample void ratio = volume of voids / volume of solids Wo - Initial water content (at start of consolidation test) PERMEABILITY TEST k - Coefficient of permeability or hydraulic conductivity is a measure of the ability of water to flow through the sample. The value of k is measured at a specified unit weight for (remoulded) cohesionless soil samples, because its value will vary with the unit weight or density of the sample during the test.

40

41 Cer ficate of Analysis Order #: Report Date: 11 Oct 2012 Client: Paterson Group Consul ng Engineers Order Date:9 Oct 2012 Client PO: Project Descrip on: PG2777 Client ID: BH3-SS Sample Date: 26-Sep Sample ID: MDL/Units Soil Physical Characteristics % Solids 0.1 % by Wt General Inorganics ph 0.05 ph Units Resistivity 0.10 Ohm.m Anions Chloride 5 ug/g dry Sulphate 5 ug/g dry Page 3 of 7

42 APPENDIX 2 FIGURE 1 - KEY PLAN DRAWING PG TEST HOLE LOCATION PLAN