draft geotechnical engineering report · draft geotechnical engineering report – building tower...

Farhi Holdings Corporation

Building Tower and Parking Garage 435 Ridout Street North London, Ontario

Draft Geotechnical Engineering Report

Date: April 5, 2017

Ref. N°: 160-B-0016783-1-GE-R-0001-0A

Unit 12 – 60 Meg Drive, London (Ontario) Canada N6E 3T6 – 519..685.6400 | F 519.685-0943 – [email protected]


Building Tower and Parking Garage 435 Ridout Street North

London, Ontario

Geotechnical Engineering Report | 160-B-0016783-1-GE-R-0001

Prepared by: DRAFT

Stephen W. Burt, P.Eng.

Consulting Geotechnical Engineer

Reviewed by : DRAFT

Colin J.W. Atkinson, M.Sc., P.Eng.

Senior Consulting Geotechnical Engineer

TABLE OF CONTENTS

160-B-0016783-1-GE-R-0001-0A

DRAFT GEOTECHNICAL ENGINEERING REPORT – BUILDING TOWER AND PARKING GARAGE, 435 R IDOUT STREET NORTH, LONDON, ONTARIO

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INTRODUCTION ............................................................................................................................................. 1

1 INVESTIGATION PROCEDURE ............................................................................................................ 2

1.1 Field Program ...................................................................................................................... 2 1.2 Laboratory Testing .............................................................................................................. 2

2 SUMMARIZED SUBSURFACE CONDITIONS .................................................................................... 3

2.1 Building tower (Boreholes 1 to 8) ........................................................................................ 3 2.2 Parking Garage (Boreholes 9 to 17) ................................................................................... 4 2.3 Atterberg Limits ................................................................................................................... 5 2.4 Summarized Groundwater Levels ....................................................................................... 5

3 DISCUSSION AND RECOMMENDATIONS ......................................................................................... 6

3.1 Excavations and Groundwater Control ............................................................................... 6 3.2 Earth Shoring ...................................................................................................................... 7 3.3 Building Tower Foundation Design ..................................................................................... 7 3.4 Parking Garage Foundation Design.................................................................................... 8 3.5 General Foundation Recommendatiosn ............................................................................. 9 3.6 Seismic Site Classification ................................................................................................ 10 3.7 Slab on Ground Construction ............................................................................................ 10 3.8 Lateral Earth Pressures and Site Drainage ...................................................................... 11 3.9 Flexible Pavement Design ................................................................................................ 11

4 STATEMENT OF LIMITATIONS .......................................................................................................... 12

Tables

Table 1 - Atterberg Limits Test Results .............................................................................................................. 5

Table 2 - Summarized Groundwater Levels ....................................................................................................... 5

Table 3 – Building Tower Highest Foundation Founding Levels ........................................................................ 7

Table 4 - Pile Types and Capacities ................................................................................................................... 8

Table 5 – Parking Garage Highest Foundation Founding Levels ....................................................................... 9

Table 4 - Pavement Design .............................................................................................................................. 12

Appendices

Appendix 1 Drawings

Appendix 2 Boreholes

Appendix 3 Figure 1

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Property and Confidentiality

“This engineering document is the property of Englobe Corp. and, as such, is protected under Copyright Law. It can only be

used for the purposes mentioned herein. Any reproduction or adaptation, whether partial or total, is strictly prohibited without

having obtained Englobe’s and its client’s prior written authorization to do so.

Test results mentioned herein are only valid for the sample(s) stated in this report.

Englobe’s subcontractors who may have accomplished work either on site or in laboratory are duly qualified as stated in our

Quality Manual’s procurement procedure. Should you require any further information, please contact your Project Manager.”


484 Richmond Street, suite 200

London, Ontario N6A 3E6

Attention: Mr. Shmuel Farhi, President

REVISION AND PUBLICATION REGISTER

Revision N° Date Modification And/Or Publication Details

0A 2017-04-05 Draft Report Issued

DISTRIBUTION

1 electronic copy Client

1 electronic copy Architects Tillmann Ruth Robinson Inc.

1 electronic copy File

160-B-0016783-1-GE-R-0001-0A


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INTRODUCTION

Englobe Corp. (Englobe) was retained by Farhi Holdings Corporation to perform a

Geotechnical Investigation at 435 Ridout Street North, London, Ontario, shown on the Location

Plan, Drawing 1 in Appendix 1.

It is proposed to construct a 32 storey building tower and a three level parking garage as

shown on the Site Plan, Drawing 2 in Appendix 1. The purpose of this investigation was to

determine the subsurface conditions at the site and, based on that information; provide

geotechnical recommendations for the design of foundations and pavements.

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1 INVESTIGATION PROCEDURE

1.1 FIELD PROGRAM

The fieldwork for this investigation involved drilling 17 boreholes from March 7th to 14th, 2016 at

locations shown on the Site Plan, Drawing 2 in Appendix 1.

The boreholes were advanced to sampling depths of 6.6 to 17.2 metres (m) using power auger

machines equipped with conventional soil sampling equipment, which were supplied and

operated by a specialist drilling company.

Soil samples were recovered from the boreholes at frequent intervals of depth using a 50 mm

O.D. split spoon sampler in accordance with the Standard Penetration Test (SPT) procedure.

The SPT N-values are shown on the borehole logs in Appendix 2.

Groundwater observations were carried out in the boreholes during and upon the completion of

drilling operations. The observations are summarized on the appended borehole logs and in

Table 2.

The fieldwork was monitored throughout by a member of our engineering staff who directed the

drilling and sampling procedures, documented the soil stratigraphies, and cared for the

recovered soil samples.

The level of the ground surface at each borehole location was related to a local benchmark,

which was taken as City of London Vertical Control Monument V92-22. This benchmark is

described as a nail set in the top of the southeast corner of a concrete wall around a ventilation

grill in front of the London and Regional Art Gallery on Ridout Street, and is located 40.0m

north of the centreline of Dundas Street and 25.0m west of the centreline of Ridout Street.

The benchmark was assigned a geodetic Elevation of 246.18m, as shown on the City of

London web site.

1.2 LABORATORY TESTING

All soil samples recovered during this investigation were returned to our laboratory for visual

examination as well as moisture content determinations. The moisture content test results are

shown on the appended borehole logs.

Additional Geotechnical laboratory testing carried out on selected soil samples are listed

below:

Two grain size analyses (MTO LS-702) (ASTM D422-63) with test results presented

graphically on Figure 1 in Appendix 3; and,

Three Atterberg Limits tests (LS 703 and LS 704) with test results presented in Table 1 and

the respective borehole logs.

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The soil samples will be stored for a period of three months from the date of storage. After this

time, they will be discarded unless prior arrangements have been made for longer storage.

2 SUMMARIZED SUBSURFACE CONDITIONS

Refer to the borehole logs in Appendix 2 for descriptions of the soil stratigraphy, results of SPT

testing, moisture content values, and groundwater observations. The following notes are

intended only to amplify this data.

2.1 BUILDING TOWER (Boreholes 1 to 8)

The proposed building area is located on the east embankment of the Thames River floodplain

that overlaps an existing building built into the hill, which is to be demolished. An older building

located at the top of the hill is to be incorporated into the new building tower.

Boreholes 1 to 4 were located at the top of the slope. Boreholes 1 to 3 revealed a surface

layer of asphalt, measuring 80 to 100mm thick, supported by 100 to 350mm of granular base

material. Borehole 4 revealed a 300 mm thick surface layer of topsoil. Beneath the topsoil and

pavement materials, Boreholes 1 to 4 encountered layers of dense to loose sand and gravel fill

materials displaying moisture contents ranging from 4 to 9%. The fill was penetrated at a

depth of about 10 m in Borehole 4, located just east of the building built into the hill, and at

depths of 1.4 to 2.9 m in Boreholes 1 to 3. Based on previous work carried out on this site, it is

known that the existing embankment was cut at an angle of 60 degrees to the horizontal and

the east wall of the building built into the hill was designed as a retaining wall, which was

backfilled with granular material. It is considered that Borehole 4 was extended through the

retaining wall granular backfill material.

Boreholes 5 to 8 were located near the toe of the slope, where Boreholes 5, 6 and 8 revealed

surface layers of topsoil measuring 300 mm to 1.4m thick. The topsoil sample in Borehole 5

yielded a moisture content of 27%. Beneath the topsoil, Boreholes 6 and 8 encountered layers

of soft to stiff silty clay fill displaying moisture contents of 12 to 36%, and the fill was penetrated

at depths of 1.0 to 2.1 m. Borehole 7 revealed a 120 mm thick surface layer of asphalt

supported by 880mm of granular fill.

Within Boreholes 1 to 8, the underlying soil consists of layers of stiff to hard silty clay to silty

clay/clayey silt till, compact to dense silt and sand materials, and dense to very dense silt and

sand till materials. The silty clay to clayey silt strata displayed natural moisture contents

ranging from 8 to 27%, the silt and sand layers displayed values of 18 to 20%, and the silt and

sand till displayed values from 7 to 12%. The boreholes were terminated within hard silty clay

to clayey silt till and very dense silt and sand till materials at depths of 6.6 to 17.2 m.

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The grain size distribution analyses test results; plotted on Figure 1 in Appendix 3; indicate that

the sand sample tested from Borehole 4 contains 67% sand 30% silt, and 3% clay.

The surface layers of topsoil revealed at Borehole 5, 6, and 8 locations, are identified as

potential sources for the generation of methane gas.

2.2 PARKING GARAGE (Boreholes 9 to 17)

The proposed parking garage is located at the top of the slope along Queens Avenue with

access ramps encroaching onto an existing slope down to the floodplain of the Thames River.

Boreholes 9, and 12 to 17, were located at the top of the slope, and Borehole 9 revealed a

300mm thick surface layer of topsoil. Boreholes 12 to 17 revealed surface layers of asphalt,

measuring 75 mm thick, supported by 200 to 800 mm of granular base. Beneath the

pavement, Boreholes 16 and 17 revealed layers of loose sand fill and silty topsoil that were

penetrated at depths of 2.4 and 0.9 m respectively. The sand fill sample from borehole 16

yielded a moisture content of 15%. In Boreholes 12 to 15, the pavement is underlain by layers

of silt, sand and cinder fill materials with fragments of brick, asphalt, concrete, glass and wood.

This fill was penetrated at depths of 8.5 to 11.5 m and it displayed moisture contents ranging

from 3 to 27%. Beneath the fill, Boreholes 12, 13 and 14 contacted layers of topsoil and loose

organic silt or marl displaying natural moisture contents of 23 to 34%, and these layers were

penetrated at depths of 11.6 to 13.0 m.

Boreholes 10 and 11 were located near the toe of the slope and beneath the surface layer of

topsoil, measuring 100 mm thick, Borehole 11 encountered loose silt and sand fill. This fill

displayed moisture contents of 11 and 28% and it was penetrated at a depth of 2.1 m.

Within Boreholes 9 to 17, the underlying soil consists of layers of firm to very stiff silty clay,

very stiff to hard silty clay to clayey silt till, loose to very dense silt, sand and gravel materials,

and dense to very dense silt till materials. The silty clay to clayey silt strata displayed natural

moisture contents ranging from 3 to 24%, the layers of silt, sand and gravel materials displayed

values of 6 to 21%, and the silt till displayed values from 7 to 12%. The boreholes were

terminated with hard silty clay to clayey silt till, very dense silt till, and dense to very dense

sand and gravel materials at depths of 6.6 to 17.2 m.

The grain size distribution analyses test results, indicate that the sand sample tested from

Borehole 13 contains 5% gravel, 83% sand, and 12% silt.

The surface layers of topsoil revealed in Boreholes 9, 10, and 11, and the buried topsoil and

organic clayey silt materials in Boreholes 12, 13, 14, and 17, are identified as potential sources

for the generation of methane gas.

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2.3 ATTERBERG LIMITS

Atterberg Limits tests were carried out on samples of the silty clay and the silty clay till

materials, and the test results are summarized in the following table.

Table 1 - Atterberg Limits Test Results

BOREHOLE

NUMBER

SAMPLE

ELEVATION

(m)

WATER

CONTENT

(%)

PLASTIC

LIMIT

(%)

LIQUID

LIMIT

(%)

PLASTICITY

INDEX

(%)

SYMBOL

04-17 234.2 22 18 36 18 CL

05-17 229.1 19 15 30 15 CL

08-17 230.5 19 13 24 11 CL (till)

The Atterberg test results indicate that the samples tested is clay of low plasticity. The moisture

content values of the silty clay samples range from 3 to 24%, which are drier than to wetter

than the measured plastic limits. The moisture content values of the silty clay till samples

range from 8 to 22%, which are drier than to wetter than the measured plastic limit.

2.4 SUMMARIZED GROUNDWATER LEVELS

The following table lists the groundwater levels measured in the open boreholes at the time of

the field work, and inferred levels of permanent saturation based on the change in colour of the

subsoil from brown to grey.

Table 2 - Summarized Groundwater Levels

Borehole

Measured Groundwater Level

During Drilling Depth (m) / Elevation

Brown/Grey Interface Level

Depth (m) / Elevation

01-17 Dry and Open 3.0 / 243.5

02-17 Dry and Open 3.7 / 242.9

03-17 Dry and Open 3.7 / 243.0

04-17 10.0 / 236.6 10.0 / 236.6

05-17 5.5 / 227.6 3.7 / 229.4

06-17 7.6 / 228.7 3.7 / 232.6

07-17 Dry & Open 2.9 / 232.1

08-17 3.7 / 229.3 3.7 / 229.3

09-17 Dry & Open 3.5 / 242.6

10-17 4.2 / 228.7 2.9 / 231.1

11-17 3.0 / 230.0 2.9 / 230.1

12-17 9.3 / 233.1 10.4 / 232.0

13-17 9.6 / 232.8 10.0 / 232.4

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Borehole

Measured Groundwater Level

During Drilling Depth (m) / Elevation

Brown/Grey Interface Level

Depth (m) / Elevation

14-17 13.1 / 230.3 13.0 / 230.4

15-17 13.1 / 230.6 13.0 / 230.7

16-17 Dry & Open 4.5 / 240.6

17-17 Dry & Open 3.0 / 242.3

3 DISCUSSION AND RECOMMENDATIONS

3.1 EXCAVATIONS AND GROUNDWATER CONTROL

The pavement, fill, topsoil, marl, firm to stiff silty clay, the silt and sand till materials, and the

layers of silt, sand and gravel materials revealed on this site which are not excessively wet can

be classified as Type 3 soil in accordance with the Occupational Health and Safety Act and

Regulations for Construction Projects. Saturated and submerged fill and non-cohesive soil

(silt, sand and gravel materials) shall be classified as Type 4 soil. In the absence of

groundwater seepage, the intact very stiff to hard silty clay to clayey silt till may be classified as

Type 2 soil.

The sides of open excavations within a Type 3 soil must be carried out using side slopes not

steeper than 1 vertical to 1 horizontal from the bottom of the excavation. Type 4 soil may be

dewatered to be classified as Type 3 soil, or adequately braced, otherwise side slopes of 1

vertical to 3 horizontal or flatter will be required for excavations intersecting Type 4 soil. The

sides of excavations within Type 2 soil may be sloped at 1 vertical to 1 horizontal above the

1.2 m near vertical cut.

Based on the borehole findings, it is estimated that the water table level within open

excavations at this site is approximated by the groundwater levels revealed within the sand and

gravel materials in Boreholes 10, 11, 14, and 15, between Elevations 229.7 and 230.6.

However, due to the low permeability characteristics of the silty clay and organic silt materials,

water can be found at higher levels perched within layers of fill and sand and gravel materials,

as demonstrated by Borehole 4, 12, and 13.

It is anticipated that groundwater and surface water entering open excavations may be

controlled by gravity drainage and filtered pumps up to 1.0 m below the groundwater table.

Lowering the groundwater table by more than 1.0 m within sand and gravel deposits will

require a permit to take water and a temporary dewatering system installed by a specialist

dewater contractor. Where groundwater seepage or sloughing from seams and layers of silt,

sand and gravel materials is occurring, it will be necessary to flatten the excavation side slopes

in order to ensure stability or be adequately braced.

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The hydraulic conductivity of the sand and gravel materials will vary depending on their texture

and, based on the gradation analyses test results shown on Figure 1 in Appendix 3, it is

estimated to be in the order of 10-2 to 10-4 cm/sec.

3.2 EARTH SHORING

For new structures constructed adjacent to property lines and existing buildings, particular care

will be required to minimize loss of ground or settlement on the adjacent properties and below

existing structures. Use of soldier piles and lagging or a continuous caisson wall may be

utilized in areas where there are no buildings or structures to provide adequate support. In

order to minimize the amount of vibration and loss of ground during the installation, a

continuous caisson wall should be utilized next to structures sensitive to disturbance.

Providing adjacent land owners give approval, lateral support can be achieved by the use of

permanent or temporary tiebacks; otherwise a temporary internal bracing system will be

required before permanent support is provided by the floor slabs.

Prior to construction, pre-condition surveys of existing adjacent infrastructure and/or structures

should be carried out. Inclinometers and/or monitoring points may also be installed and

monitored to determine if displacements of buildings or shoring systems occur.

3.3 BUILDING TOWER FOUNDATION DESIGN

It is proposed to support the building tower with a raft foundation. All pavement, fill, topsoil,

loose soil, and the firm to stiff soil, must be removed from new raft foundation area, and the

following table provides the highest founding levels at Borehole 1 to 8 locations where the

approved native subgrades will provide a maximum serviceability limits states (SLS) design

pressure of 240 kPa (5,000 psf).

Table 3 – Building Tower Highest Foundation Founding Levels

BOREHOLE

HIGHEST EL. / DEPTH FOR A

SLS DESIGN PRESSURE OF

240 KPA (5,000 PSF)

01-17 242.7 / 3.8 m

02-17 242.7 / 3.8 m

03-17 243.6 / 3.1 m

04-17 235.8 / 10.7 m

05-17 231.6 / 1.5 m

06-17 234.8 / 1.5 m

07-17 233.5 / 1.5 m

08-17 230.4 / 2.6 m

For ultimate limit states design, factored geotechnical resistance values of 335 kPa (7,000 psf)

may be used, where the resistance factor is equal to 0.5.

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3.4 PARKING GARAGE FOUNDATION DESIGN

It is proposed to construct a 3 storey parking garage featuring slab on grade construction.

Extensive amounts of environmentally impacted fill materials were revealed in the area

represented by the locations of Boreholes 12 to 15. A deep foundation system may be

installed to support the slab on grade structure. Due to the native subgrade consisting of

saturated and submerged sand and gravel materials, it is considered that installation of a

caisson foundation system is not feasible.

It is therefore recommended that a deep foundation system consist of driven steel piles and the

use of 12BP53 and 12BP74 H-piles (imperial units) are considered more suitable than tube

piles to achieve penetration into the the dense to very dense subsoil. The pile tips should be

protected with a driving shoe (OPSS 3301) or rock point to avoid damage to the lower section

of the piles.

The following maximum serviceability limits states (SLS) design loads may be used for pile

design.

Table 4 - Pile Types and Capacities

TYPE OF PILE SLS DESIGN LOADS

KN KIPS

12BP53 H-pile (imperial) 832 187

12BP74 H-pile (imperial) 1155 260

For ultimate limit states design (ULS) a factored geotechnical resistance value equal to 1.2

times the SLS design load may be used where the resistance factor is equal to 0.4.

For the 12BP53 and 12BP74 H-piles properly connected to the pile cap, the estimated

horizontal resistance of the piles is 75 kN at Ultimate Limit States and 25 kN at Serviceability

Limit States per pile.

The minimum driving energy for the H-piles shall be 35,000 J (26,000 foot pounds) per blow,

and it is anticipated that the piles will reach a suitable set once driven 5.0 to 8.0 m into the

dense to very dense subsoil. To avoid damage to the piles, refusal should be considered as 5

blows of an adequate hammer producing a total penetration of 6.0 mm (0.25 inches). Care

shall be taken to determine any displacement uplift due to driving of nearby piles, and in cases

where uplift is measured the pile must be re-driven to its original set. Total settlement of the

pile foundation is estimated to not exceed 10 mm.

The actual penetration and pile set characteristics will be dependent on the load carrying

capacity of the pile and the driving equipment used by the contractor, and the contractor should

therefore submit the pile hammer data for review by the geotechnical engineer.

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Alternatively, levels of underground parking may be provided by removing the fill and organic

clayey silt and founding the structure on conventional spread footings. However, this may

involve extensive groundwater control requirements in the area represented by the locations of

Boreholes 11 to 14 where the competent native subgrade was encountered at and below the

measured groundwater levels, particularly at Borehole 13 location where heaving sand was

revealed. Furthermore, additional environmental sampling and testing may be required in the

area represented by the location Borehole 12 to 15 locations prior to removal of fill from the

site.

For conventional spread foundation design, the following table provides the highest founding

levels at Borehole 9 to 15 locations where the approved native subgrades will provide a

maximum serviceability limits states (SLS) design pressure of 240 kPa (5,000 psf).

Table 5 – Parking Garage Highest Foundation Founding Levels

BOREHOLE

HIGHEST EL. / DEPTH FOR A

SLS DESIGN PRESSURE OF

240 KPA (5,000 PSF)

09-17 244.6 / 1.5 m

10-17 233.1 / 0.8 m

11-17 229.9 / 3.1 m

12-17 228.7 / 13.7 m

13-17 228.7 / 13.7 m

14-17 228.7 / 13.7 m

15-17 231.5 / 12.2 m

16-17 242.0 / 3.1 m

17-17 243.0 / 2.3 m

3.5 GENERAL FOUNDATION RECOMMENDATIONS

In order to minimize the disturbance of soil subgrades it is recommended that foundation

excavations be carried out using a smooth-blade bucket. The founding subgrade shall be

covered with a mat of 20 MPa concrete to protect the integrity of the subgrade from

disturbance due to ponding water and/or construction activities.

Where required, the approved native subgrade can be raised to a higher founding level by

placement of 20 MPa concrete or constructing engineered fill consisting of imported OPSS

Granular ‘A’ material. Engineered fill must extend outside the foundation area for a minimum

horizontal distance equal to the depth of fill placed below the footing founding level. The

engineered fill shall be placed in maximum 200 mm thick lifts, and each lift must be compacted

to a minimum of 100% of the materials maximum standard Proctor dry density (MSPDD) under

the full time inspection and testing of the geotechnical consultant.

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To provide sufficient protection against heave due to frost action, all exterior footings and

footings in non-heated areas must incorporate a minimum depth of soil cover of 1.2 m between

the footing subgrade and the finished ground surface.

3.6 SEISMIC SITE CLASSIFICATION

The borehole findings and laboratory testing results indicate that the ground on this site can be

categorized as Site Class D in accordance with Table 4.1.8.4.A of the 2012 Ontario Building

Code.

3.7 SLAB ON GROUND CONSTRUCTION

All topsoil, organic, wet, soft, frozen and otherwise deleterious materials must be removed from

the ground surface, and the subgrade shall be proof-rolled with vibratory roller. Spongy zones

revealed during the proof-roll shall be subexcavated. Subexcavated zones, low-lying areas,

and interior foundation trench excavations shall be backfilled with approved granular pit-run

material compacted throughout to a minimum of 98% MSPDD.

It is recommended that concrete floor slabs be constructed on a minimum 200 mm thickness of

19 mm clear crushed stone or Granular ‘A’ material compacted to 100% MSPDD. To minimize

shrinkage cracking and curling of the slab, the top of the floor slab must be kept moist as the

concrete cures.

To prevent the migration of moisture vapour into the building from beneath ground floor slabs,

particularly where moisture sensitive floor coverings are placed, a vapour retarder shall be

placed directly beneath the floor slab that meets the requirements of the designer and flooring

manufacturer. Prior to installing moisture sensitive floor coverings, the moisture content of the

concrete slab must be determined at operational conditions by internal relative humidity testing

to ensure an acceptable slab moisture content. It should be noted that it typically takes more

than 90 days at operational conditions to lower the slab’s internal relative humidity to 85%.

Different flooring systems have different responses to slab moisture (i.e. some systems can

tolerate more moisture than others), and the flooring contractor must assess the floor moisture

levels with respect to their flooring components.

Concrete slabs exposed to freezing temperatures should be provided with 50 mm thick rigid

Styrofoam insulation below the slab in order to prevent differential settlements from frost heave

and thaw settlement. All weather exposed concrete shall have 5 to 8% air entrainment or as

otherwise specified in Tables 2 and 4 of CSA A23.1.

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3.8 LATERAL EARTH PRESSURES AND SITE DRAINAGE

In the design of retaining walls with rigid lateral support, the lateral earth pressure will increase

uniformly with depth, and the pressure, p, at any depth, h, can be calculated with the equation:

p = Ko (γh+q)

where Ko = earth pressure coefficient at rest, 0.5

γ = unit weight of backfill, 22.0 kN/m3 (140 pcf)

q = effective value of any surcharge acting close to the wall.

The above expression assumes level grades beside the wall and the backfill consisting of free-

draining granular material with a drainage tile placed at the footing level to prevent the build-up

of hydrostatic pressures behind the wall.

For non-rigid retaining wall design, the coefficient of earth pressure may be reduced to 0.35.

Buildings with the floor levels at or above the surrounding ground surface and the ground

surface sloping away from the building will not require perimeter tile drains. Basement or pit

areas will require a perimeter tile drain at the footing level to prevent a build-up of hydrostatic

pressure against the foundation wall, and the tile must outlet to a permanent drainage system,

such as a sewer or sump pump. A check valve shall be provided to prevent the seepage of

backup water into the drainage systems from an outlet sewer system. To provide adequate

filter protection against removal of the subsoil, the tile must be surrounded by 150 mm of pea

stone (10 mm aggregate) or 19 mm clear crushed stone, and the stone must be wrapped with

filter fabric, such as Terrafix 270R, Mirafi 140NS, Amoco 4535 or equivalent.

It is recommended that basement foundation walls be damp-proofed to prevent moisture

penetration. Where walls are cast against a shoring system, approved membranes and/or

drainage boards shall be applied to the shoring to allow for drainage to the perimeter drainage

tiles and prevent moisture penetration.

3.9 FLEXIBLE PAVEMENT DESIGN

Preparation of pavement subgrades should be carried out as outlined for slab on grade

construction.

The approved subgrade may be raised to design subgrade level with approved compactable

on-site soil, providing it is placed in maximum 300 mm thick lifts and each lift is compacted to

at least 95% of the material’s MSPDD.

It is anticipated that new pavement areas will be subjected to either light or heavy traffic. Light

duty areas are defined as passenger car parking only. Heavy duty areas are main driveways

and routes where trucks would travel. Under dry subgrade and weather conditions during

construction, the following pavement designs are recommended.

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Table 6 - Pavement Design

STREET

HL 3

SURFACE

ASPHALT

HL 8 BASE

ASPHALT

GRANULAR ‘A’

BASE

GRANULAR ‘B’

SUB-BASE

Light Duty 40 mm 50 mm 150 mm 300 mm

Heavy Duty 50 mm 60 mm 150 mm 400 mm

To provide drainage for the granular base and sub-base materials, including the underground

parking slabs, the subgrades shall be graded to allow favourable drainage to catch basins, and

3 metre long filtered sub-drains installed at the subgrade level at each catch basin location.

The subdrains should extend out of each face of catch basins located in parking areas, and

parallel to the edge of the pavement for catch basins on the side of roadways.

Prior to placing the pavement Granular ‘B’ sub-base layer, the road subgrade shall be proof-

rolled to compact loose zones and to identify spongy areas. Any spongy zones identified shall

be sub-excavated and replaced with drier material compacted to 98% MSPDD.

To provide uniform support for the asphalt materials, the granular base and sub-base materials

shall be compacted to 100% of their MSPDD. The asphalt must be supplied and placed in

accordance with OPSS Forms 310 and 1150.

4 STATEMENT OF LIMITATIONS

The geotechnical recommendations provided in this report are applicable only to the project

described in the text and then only if constructed substantially in accordance with the details

stated in this report. Since all details of the design may not be known at the time of report

preparation, we recommend that we be retained during the final design stage to verify that the

geotechnical recommendations have been correctly interpreted in the design. Also, if any

further clarification and/or elaboration are needed concerning the geotechnical aspects of the

project, Englobe Corp. should be contacted. We recommend that we be retained during

construction to confirm that the subsurface conditions do not deviate materially from those

encountered in the test holes and to ensure that our recommendations are properly

understood. Quality assurance testing and inspection services during construction are a

necessary part of the evaluation of the subsurface conditions.

The geotechnical recommendations provided in this report are intended for the use of the

Client or its’ agent and may not be used by a Third Party without the expressed written consent

of Englobe and the Client. They are not intended as specifications or instructions to

contractors. Any use which a contractor makes of this report, or decisions made based on it,

are the responsibility of the contractor. The contractor must also accept the responsibility for

means and methods of construction, seek additional information if required, and draw their own

conclusions as to how the subsurface conditions may affect their work. Englobe accepts no

160-B-0016783-1-GE-R-0001-0A


13

responsibility and denies any liability whatsoever for any damages arising from improper or

unauthorized use of the report or parts thereof.

It is important to note that the geotechnical assessment involves a limited sampling of the site

gathered at specific test hole locations and the conclusions in this report are based on this

information gathered and in accordance with normally accepted practices. The subsurface

geotechnical, hydrogeological, environmental and geologic conditions between and beyond the

test holes will differ from those encountered at the test holes. Also such conditions are not

uniform and can vary over time. Should subsurface conditions be encountered which differ

materially from those indicated at the test holes, we request that we be notified in order to

assess the additional information and determine whether or not changes should be made as a

result of the conditions. Englobe will not be responsible to any party for damages incurred as a

result of failing to notify Englobe that differing site or subsurface conditions are present upon

becoming aware of such conditions.

The professional services provided for this project include only the geotechnical aspects of the

subsurface conditions at the site, unless otherwise stated specifically in the report. The

recommendations and opinions given in this report are based on our professional judgment

and are for the guidance of the Client or its’ Agent in the design of the specific project. No

other warranties or guarantees, expressed or implied, are made.

Appendix 1 Drawings

Drawing 1: Location Plan

Drawing 2: Site Plan

SITE

THAMES RIVER

10 c

m5

04

32

1

Title

Project

01 of 02

435 Ridout Street North, London, Ontario

NOTES :

1-REFERENCE : City of London online mapping tool - City Map Gallery,

accessed March 2017 (www.maps.london.ca)

2-Drawing scale may be distorted due to file conversion and/or copying.

Measurements taken from the drawing must be verified in the field.

0 100 200

SCALE 1:7500

300 m

EL.246.50

EL.246.57

EL.246.68

EL.246.58

EL.233.14

EL.236.31

EL.234.99

EL.233.01

EL.246.10

EL.233.96

EL.232.98

EL.242.42

EL.242.41

EL.243.38

EL.243.71

EL.245.15

EL.245.35

QU

EE

NS

AV

EN

UE

RID

OU

T S

TR

EE

T N

OR

TH

Title

Project

10 c

m5

04

32

1

02 02

435 Ridout Street North, London, Ontario

LEGEND :

NOTES :

1-REFERENCE : Base image from Tillmann Ruth Robinson Architects,

Drawing No. A2 - Proposed Bore Hole Locations on Proposed Site dated

January 27, 2017, Filename: RFP Geotech Investigation 20170127.pdf,

Page 6.

2-Temporary Benchmark - City of London vertical control monument V92-22.

Elevation: 246.18 m (Geodetic)

3-Drawing scale may be distorted due to file conversion and/or copying.

Measurements taken from the drawing must be verified in the field.

BOREHOLE LOCATION

GROUND SURFACE ELEVATION (m)EL.246.50

0 10 20

SCALE 1:750

30 m

Appendix 2 Boreholes

List of Abbreviations

Boreholes 01-17 to 17-17

LIST OF ABBREVIATIONS

The abbreviations commonly employed on the borehole logs, on the figures, and in the text of the report, are as follows:

Sample Types Soil Tests and Properties

AS Auger Sample CS Chunk Sample RC Rock Core SS Split Spoon TW Thinwall, Open WS Wash Sample BS Bulk Sample GS Grab Sample WC Water Content Sample TP Thinwall, Piston

SPT UC FV ø γ

wp w wl IL Ip

PP

Standard Penetration Test Unconfined Compression Field Vane Test Angle of internal friction Unit weight Plastic limit Water content Liquid limit Liquidity index Plasticity index Pocket penetrometer

Penetration Resistances Dynamic Penetration

Resistance The number of blows by a 63.5 kg (140 lb.) hammer dropped 760 mm (30 in.) required to drive a 50 mm (2 in.) diameter 60 º cone a distance 300 mm (12 in.). The cone is attached to 'A' size drill rods and casing is not used.

Standard Penetration Resistance, N (ASTM D1586)

The number of blows by a 63.5 kg (140 lb.) hammer dropped 760 mm (30 in.) required to drive a standard split spoon sampler 300 mm (12 in.)

WH sampler advanced by static weight of hammer

PH sampler advanced by hydraulic pressure

PM sampler advanced by manual pressure

Soil Description

Cohesionless Soils Compactness Condition Very Loose Loose Compact Dense Very Dense

SPT N-Value (blows per 0.30 m)

0 to 4 4 to 10 10 to 30 30 to 50 over 50

Relative Density (Dr) (%)

0 to 20 20 to 40 40 to 60 60 to 80 80 to 100

Cohesive Soils Consistency Very Soft Soft Firm Stiff Very Stiff Hard

Undrained Shear Strength (Cu)

kPa less than 12

12 to 25 25 to 50 50 to 100 100 to 200 over 200

psf less than 250

250 to 500 500 to 1000 1000 to 2000 2000 to 4000

over 4000

DTPL APL WTPL

Drier than plastic limit About plastic limit Wetter than plastic limit

sauewe

Typewritten Text

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Typewritten Text

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Typewritten Text

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Typewritten Text

Appendix 3 Figure 1

Grain Size Distribution Analyses

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