A REPORT TO MIL CON THREE DEVELOPMENTS LIMITED A ... · A REPORT TO MIL CON THREE DEVELOPMENTS LIMITED A GEOTECHNICAL INVESTIGATION FOR PROPOSED RESIDENTIAL DEVELOPMENT BRITANNIA

A REPORT TO MIL CON THREE DEVELOPMENTS LIMITED

A GEOTECHNICAL INVESTIGATION FOR

PROPOSED RESIDENTIAL DEVELOPMENT

BRITANNIA ROAD WEST AND THOMPSON ROAD SOUTH TOWN OF MILTON

REFERENCE NO. 1806-S145

AUGUST 2018

DISTRIBUTION

3 Copies - Mil Con Three Developments Limited 1 Copy - Soil Engineers Ltd. (Mississauga) 1 Copy - Soil Engineers Ltd. (Richmond Hill)

Reference No. 1806-S145 ii

TABLE OF CONTENTS

1.0 INTRODUCTION ...................................................................................... 1

2.0 SITE AND PROJECT DESCRIPTION ..................................................... 2

3.0 FIELD WORK ............................................................................................ 3

4.0 SUBSURFACE CONDITIONS ................................................................. 4

4.1 Ploughed Earth ............................................................................... 4 4.2 Earth Fill ......................................................................................... 4 4.3 Silty Clay Till ................................................................................. 5 4.4 Sandy Silt Till ................................................................................. 7 4.5 Compaction Characteristics of the Revealed Soils ........................ 8

5.0 GROUNDWATER CONDITIONS ............................................................ 11

6.0 DISCUSSION AND RECOMMENDATIONS ......................................... 13

6.1 Foundations .................................................................................... 15 6.2 Engineered Fill ............................................................................... 16 6.3 Underground Structure and Slab-on-Grade .................................... 19 6.4 Underground Services .................................................................... 20 6.5 Backfilling in Trenches and Excavated Areas ............................... 21 6.6 Pavement Design ............................................................................ 23 6.7 Soil Parameters ............................................................................... 25 6.8 Excavation ...................................................................................... 26

7.0 LIMITATIONS OF REPORT .................................................................... 27

Reference No. 1806-S145 iii

TABLES

Table 1 - Estimated Water Content for Compaction ............................................. 9

Table 2 - Groundwater Levels ............................................................................... 11

Table 3 - Founding Levels ..................................................................................... 15

Table 4 - Pavement Design .................................................................................... 24

Table 5 - Soil Parameters ....................................................................................... 25

Table 6 - Classification of Soils for Excavation .................................................... 26

ENCLOSURES Logs of Boreholes ............................................................................ Figures 1 to 10 Grain Size Distribution Graphs ........................................................ Figure 11 Borehole Location Plan ................................................................... Drawing No. 1 Subsurface Profile ............................................................................ Drawing No. 2

Reference No. 1806-S145 1

1.0 INTRODUCTION

In accordance with written authorization from Ms. Maria Herrera of Mil Con Three

Developments Limited dated June 21, 2018, a geotechnical investigation was carried

out on a parcel of land located on the north side of Britannia Road West and west of

Thompson Road South in the Town of Milton.

The purpose of the investigation was to reveal the subsurface conditions and to

determine the engineering properties of the disclosed soils for the design and

construction of a proposed residential development.

The findings and resulting geotechnical recommendations are presented in this

Report.


2.0 SITE AND PROJECT DESCRIPTION

The Town of Milton is situated in the physiographical region known as the

Horseshoe Moraine. The region comprises complex till ridges, with interspersed

kame moraines, moulded till plains, outwash plains and spillways. Peel ponding

(glacial lake) also invaded the region and eroded parts of the tills which have been

filled with lacustrine sands, silt, clay and/or reworked till. Shale bedrock of

Queenston and/or Meaform Formations are known to occur in the region at shallow

to moderate depths.

The subject property, almost rectangular in shape and encompassing an area of 19.2

hectares, is located on the north side of Britannia Road West, approximately 300 m

west of Thompson Road South in the Town of Milton. At the time of investigation,

part of the property was a farmfield and the remaining portion towards the west was

wooded, with a creek flowing through the wood land. The existing site gradient is

relatively flat with minor undulations towards the south and west.

At the time of report preparation, details of the proposed development were not

available. However, it is assumed that the development will consist of a residential

subdivision with municipal services and roadways meeting urban standards.


3.0 FIELD WORK

The field work, consisting of ten (10) boreholes and extending to a depth of 6.2 or

6.4 m from the prevailing ground surface, was conducted on July 23 and 24, 2018, at

the locations of the farmfield as shown on the Borehole Location Plan, Drawing

No. 1. No borehole was completed in the wooded area due to limited accessibility for

the drilling equipment.

The boreholes were advanced at intervals to the sampling depths by a track-mounted,

continuous-flight power-auger machine equipped for soil sampling. Standard

Penetration Tests, using the procedures described on the enclosed “List of

Abbreviations and Terms”, were performed at the sampling depths. The test results

are recorded as the Standard Penetration Resistance (or ‘N’ values) of the subsoil.

The relative density of the granular strata and the consistency of the cohesive strata

are inferred from the ‘N’ values. Split-spoon samples were recovered for soil

classification and laboratory testing.

The field work was supervised and the findings were recorded by a Geotechnical

Technician.

The ground elevation at each borehole location was established by a hand-held

Global Navigation Satellite System surveying equipment (Trimble Geoexplorer 6000

series).


4.0 SUBSURFACE CONDITIONS

The investigation conducted in the farmfield, revealed that beneath a layer of

ploughed earth, with earth fill in places, the site is generally underlain by a native

stratum of silty clay till and sandy silt till.

Detailed descriptions of the encountered subsurface conditions are presented on the

Borehole Logs, comprising Figures 1 to 10, inclusive. The revealed stratigraphy is

plotted on the Subsurface Profile, Drawing No. 2. The engineering properties of the

disclosed soils are discussed herein.

4.1 Ploughed Earth (All Boreholes)

A layer of ploughed earth, 30 to 60 cm in thickness, was contacted at the ground

surface in all boreholes. It consists a mixture of sandy silt and silty clay, with gravel,

topsoil and rootlets.

The ploughed earth is compressible and it can be reused for landscaping purposes

only. Due to its humus content, the topsoil may produce volatile gases and generate

an offensive odour under anaerobic conditions. Therefore, it must not be buried

below any structure or deeper than 1.2 m from the finished grade, so that it will not

have an adverse impact on the environmental well-being of the developed areas.

4.2 Earth Fill (Borehole 7)

A layer of earth fill was contacted below the ploughed earth in Borehole 7. It consists

of silty clay, with some brick fragments, mixture of topsoil and rootlet inclusions.

The earth fill extends to a depth of 0.6 to 1.1 m from the prevailing ground surface.


The earth fill is in moist condition, having the natural water content of 23%. It is not

suitable for supporting any structure sensitive to movement. In using the fill for

structural backfill, pavement subgrade or slab-on-grade construction, it should be

subexcavated, sorted free of serious topsoil inclusions or deleterious materials, and

properly recompacted in layers.

4.3 Silty Clay Till (All boreholes)

The silty clay till was encountered below the ploughed earth or earth fill in the

boreholes. It consists of a random mixture of soils; the particles sizes range from

clay to gravel, with the silt and clay fraction exerting the dominant influence on its

soil properties. Sample examinations show that the till contains trace sand and a trace

of gravel with occasional sand seams and layers. The structure of the clay till is

heterogeneous, indicating a glacial deposit.

The obtained ‘N’ values in the clay till range from 19 to over 100 blows per 30 cm of

penetration, with a median of 45 blows per 30 cm of penetration, showing the

consistency of the clay till is very stiff to hard, being generally hard.

Hard resistance to augering was encountered in places, showing occasional cobbles

and boulders in the till stratum.

The Atterberg Limits of a representative sample and the natural water content values

of all the clay till samples were determined. The results are plotted on the Borehole

Logs and summarized below:


Liquid Limit 29%

Plastic Limit 17%

Natural Water Content 9% to 20% (median 13%)

The results indicate that the clay till deposit is a cohesive material with low plasticity.

The natural water content values generally lie below its plastic limit, confirming the

consistency of the clay till as determined from the ‘N’ values.

Grain size analyses were performed on 3 representative samples of the clay till; the

results are plotted on Figure 11.

Based on the above findings, the soil engineering properties of the clay till pertaining

to the project are given below:

• Highly frost susceptible and low water erodibility.

• Low permeability, with an estimated coefficient of permeability of 10-7 cm/sec,

a percolation rate of over 80 min/cm, and runoff coefficients of:

Slope

0% - 2% 0.15

2% - 6% 0.20

6% + 0.28

• Its shear strength is primarily derived from consistency which is inversely

related to its moisture content. It contains silt and sand; therefore, its shear

strength is also augmented by internal friction.

• It will generally be stable in a relatively steep cut; however, prolonged exposure

will allow the sand and silt seams and layers to become saturated, which may

lead to localized sloughing.


• A very poor pavement-supportive material, with an estimated California Bearing

Ratio (CBR) value of 3%.

• Moderately high corrosivity to buried metal, with an estimated electrical

resistivity of 3000 ohm·cm.

4.4 Sandy Silt Till (All Boreholes)

The sandy silt till deposit was encountered below silty clay till below 1.4 to 5.6 m. It

extends to the maximum investigated depth of boreholes and consist of a random

mixture of soil particle sizes ranging from clay to gravel, with the sand and silt being

the predominant fraction.

The obtained ‘N’ values of the till deposits range from 60 to more than 100 blows per

30 cm of penetration, showing the relative density of the silt till deposit is very dense.

Hard resistance to augering was encountered in places, showing occasional cobbles

and boulders in the till stratum.

The natural water content of the till samples was determined, and the results are

plotted on the Borehole Logs; the values range from 5% to 13%, with a median of

9%, showing the silt till is in damp to moist conditions, being generally moist.

Based on the above findings, the engineering properties of the silt till deposit are

given below:

• Moderately frost susceptible and low water erodibility.

• Relatively low permeability, with an estimated coefficient of permeability of

10-6 cm/sec, a percolation rate of about 60 min/cm, and runoff coefficients of:


Slope

0% - 2% 0.15

2% - 6% 0.20

6% + 0.28

• A frictional soil, its shear strength is derived from internal friction, thus being

density dependent.

• It will generally be stable in a relatively steep cut; however, prolonged exposure

will allow the fissures in the sand seams to become saturated, which may lead to

localized sloughing.

• A poor pavement-supportive material, with an estimated CBR value of 5%.

• Moderately low corrosivity to buried metal, with an estimated electrical

resistivity of 5000 ohm·cm.

4.5 Compaction Characteristics of the Revealed Soils

The obtainable degree of compaction is primarily dependent on the soil moisture and,

to a lesser extent, on the type of compactor used and the effort applied.

As a general guide, the typical water content values of the revealed soils for Standard

Proctor compaction are presented in Table 1.


Table 1 - Estimated Water Content for Compaction

Soil Type

Determined Natural Water Content (%)

Water Content (%) for Standard Proctor Compaction

100% (optimum) Range for 95% or +

Earth Fill 23 17 12 to 22

Silty Clay Till 10 to 20

(median 13) 16 12 to 20

Sandy Silt Till 8 to 13 (median 9) 12 8 to 15

The majority of the on-site soils are suitable for 95% or + Standard Proctor

compaction. However, any wet material will require aeration by spreading it on the

ground, during dry and warm weather or mixing with drier soils prior to structural

compaction.

The earth fill should be subexcavated, sorted free of organic or topsoil below

structured uses. The ploughed earth can only be reused as topsoil in landscape

contouring.

The tills should be compacted using a heavy-weight, kneading-type roller. The lifts

for compaction should be limited to 20 cm, or to a suitable thickness as assessed by

test strips performed by the equipment which will be used at the time of construction.

Boulders over 15 cm in size must either be sorted or removed for structural backfill.

When compacting chunks of till on the dry side of the optimum, the compactive

energy will frequently bridge over the chunks in the soil and be transmitted laterally

into the soil mantle. Therefore, the lifts of these soils must be limited to 20 cm or

less (before compaction).


If the compaction of the soils is carried out with the water content within the range

for 95% Standard Proctor dry density but on the wet side of the optimum, the surface

of the compacted soil mantle will roll under the dynamic compactive load. This is

unsuitable for pavement construction since each component of the pavement structure

is to be placed under dynamic conditions which will induce the rolling action of the

subgrade surface and cause structural failure of the new pavement. The foundations

for structures and utilities will be placed on a subgrade which will not be subjected to

impact loads. Therefore, the structurally compacted soil mantle with the water

content on the wet side or dry side of the optimum will provide an adequate subgrade

for the construction.

The presence of boulders will prevent transmission of the compactive energy into the

underlying material to be compacted. If an appreciable amount of boulders over

15 cm in size is mixed with the material, it must either be sorted or the material must

not be used for construction of engineered fill and/or structural backfill.


5.0 GROUNDWATER CONDITIONS

The boreholes were checked for the presence of groundwater and the occurrence of

cave-in upon their completion. The recorded groundwater data in the boreholes are

plotted on the Borehole Logs and summarized in Table 2.

Table 2 - Groundwater Levels

Borehole No.

Ground Elevation

(m)

Depth of Borehole

(m)

Groundwater Level Upon Completion

Depth (m) Elevation (m)

1 192.6 6.2 Dry -

2 192.1 6.2 Dry -

3 191.6 6.2 Dry -

4 192.0 6.2 Dry -

5 191.1 6.2 5.9 185.2

6 190.9 6.4 Dry -

7 191.2 6.2 5.4 185.8

8 192.2 6.4 Dry -

9 190.7 6.4 Dry -

10 191.5 6.4 Dry -

Groundwater was encountered in Boreholes 5 and 7 at a depth of 5.9 m and 5.4 m,

respectively, below the prevailing ground surface, or El. 185.2 m and El. 185.8 m,

upon completion of drilling. The rest of the boreholes remained dry and open upon

the completion of drilling. The groundwater may represent perched water in the sand

seams within the till deposits. It may fluctuate with the seasons.


In excavation, the groundwater yield is expected to be slow in rate and limited in

quantity. It can be drained to a sump pit and removed by conventional pumping.


6.0 DISCUSSION AND RECOMMENDATIONS

The investigation has revealed that beneath the ploughed earth, with a layer of earth

fill in places, the site is generally underlain by a stratum of very stiff to hard,

generally hard silty clay till and very dense sandy silt till deposit in the lower

stratigraphy.

Groundwater was recorded in Boreholes 5 and 7 at a depth of 5.9 m and 5.4 m

respectively below the prevailing ground surface, or El. 185.2 m and El. 185.8 m,

upon completion of drilling. The rest of the boreholes remained dry and open upon

the completion of drilling. The groundwater may represent perched water in the sand

seams within the till deposits. It may fluctuate with the seasons.

The site will be re-graded for development. Details of the development, however,

were not available at the time of report preparation. It is assumed that the

development will consist of a residential subdivision with municipal services and

roadways meeting urban standards.

The geotechnical findings which warrant special consideration are presented below:

1. The ploughed earth and the topsoil in the woodland must be removed for the

project construction. They are compressible under loads and unsuitable for

engineering applications. Therefore, they should be placed in landscaped areas

only and should not be buried within the building envelope, or deeper than

1.2 m below the exterior finished grade of the project.

2. The existing earth fill are not suitable for supporting any structure sensitive to

movement. In using the fill for structural backfill, pavement subgrade or slab-


on-grade construction, it should be subexcavated, sorted free of serious topsoil

inclusions or deleterious materials, and properly compacted in layers.

3. If the site is to be regraded for development, it is generally more economical to

place an engineered fill for normal house footing, sewer and road construction.

4. The foundations of the proposed structures can consist of conventional spread

and strip footings, founded on the sound native till deposit or engineered fill.

The footings must be designed in accordance with the recommended bearing

pressures in Section 6.1 and the footing subgrade must be inspected by a

geotechnical engineer to ensure that its condition is compatible with the design

of the foundations.

5. For slab-on-grade construction, the slab should be constructed on a granular

base, 20 cm thick, consisting of 20-mm Crusher-Run Limestone, or equivalent,

compacted to its maximum Standard Proctor dry density.

6. A Class ‘B’ bedding, consisting of compacted 20-mm Crusher-Run Limestone,

is recommended for the construction of the underground services. The pipe

joints should be leak-proof, or wrapped with an appropriate waterproof

membrane.

7. All excavations should be carried out in accordance with Regulation 213/91.

The recommendations appropriate for the project described in Section 2.0 are

presented herein. One must be aware that the subsurface conditions may vary

between boreholes. Should this become apparent during construction, a geotechnical

engineer must be consulted to determine whether the following recommendations

require revision.


6.1 Foundations

It is recommended that normal spread and strip footings of the proposed structures

are placed onto the sound native till or engineered fill. As a general guide, the

recommended soil pressures for use in the design of the footings, together with the

corresponding suitable founding levels, are presented in Table 3.

Table 3 - Founding Levels

Borehole No.

Recommended Maximum Allowable Soil Pressure (SLS)/ Factored Ultimate Soil Bearing Pressure (ULS)

and Suitable Founding Level

300 kPa (SLS) 500 kPa (ULS)

500 kPa (SLS) 800 kPa (ULS)

Depth (m) El. (m) Depth (m) El. (m)

1 0.8 or + 191.8 or - 3.0 or + 189.6 or -

2 0.8 or + 191.3 or - 1.5 or + 190.6 or -

3 0.8 or + 190.8 or - 2.3 or + 189.3 or -

4 0.8 or + 191.2 o r- 3.0 or + 189.0 or -

5 0.8 or + 190.3 or - 2.3 or + 188.8 or -

6 0.8 or + 190.1 or - 3.0 or + 187.9 or -

7 1.3 or + 189.9 or - 2.3 or + 188.9 or -

8 0.8 or + 191.4 or - 1.5 or + 190.7 or -

9 1.5 or + 189.2 or - 4.6 or + 186.1 or -

10 0.8 or + 190.7 or - 2.3 or + 189.2 or -

The recommended bearing pressures (SLS) for normal footings incorporate a safety

factor of 3. The total and differential settlements of the footings are estimated to be

25 mm and 15 mm, respectively.


Higher design bearing pressures of 900 kPa (SLS) may be used for foundations

founded at deeper levels at some particular locations. The final design of structures

and foundations can be reviewed by the geotechnical engineer. Additional boreholes

may be required to verify the subsurface conditions for the design of these structures

with higher design bearing pressures.

The footing subgrade must be inspected by a geotechnical engineer, or a geotechnical

technician under the supervision of a geotechnical engineer, to assess its suitability

for bearing the designed foundations.

Footings exposed to weathering, or in unheated areas, should have at least 1.2 m of

earth cover for protection against frost action.

The foundations should meet the requirements specified in the latest Ontario Building

Code. The structure should be designed to resist an earthquake force using Site

Classification ‘C’ (very dense soil).

Most of the in situ soils have high soil-adfreezing potential. In order to alleviate the

risk of frost damage, the foundation walls of the proposed buildings must be

constructed of concrete and either the backfill must consist of non-frost-susceptible

granular material or the foundation walls must be shielded with layers of

polyethylene slip-membrane between the concrete wall and the native backfill.

6.2 Engineered Fill

Where the site is to be regarded for the development, it is generally more economical

to place engineered fill for normal footing, sewer and road construction.


The engineering requirements for a certifiable fill for road construction, municipal

services, slab-on-grade, and footings designed with a Maximum Allowable Soil

Pressure (SLS) of 150 kPa and a Factored Ultimate Soil Bearing Pressure (ULS) of

250 kPa for normal footings are presented below:

1. The existing topsoil and ploughed earth must be stripped and removed.

2. The existing earth fill must be subexcavated, inspected and proof-rolled prior to

any fill placement, in order to assess any subexcavation requirements. The

stripped surface must be surface compacted.

3. Inorganic soils must be used, and they must be uniformly compacted in lifts

20 cm thick to 98% or + of their maximum Standard Proctor dry density up to

the proposed finished grade. The soil moisture must be properly controlled on

the wet side of the optimum.

4. If the house foundations are to be built soon after the fill placement, the

densification process for the engineered fill must be increased to 100% of the

maximum Standard Proctor compaction.

5. If imported fill is to be used, it should be inorganic soils, free of deleterious or

any material with environmental issue (contamination). Any potential imported

earth fill from off site must be reviewed for geotechnical and environmental

quality by the appropriate personnel as authorized by the developer or agency,

before being hauled to the site.

6. If the engineered fill is to be left over the winter months, adequate earth cover

or equivalent must be provided for protection against frost action.

7. The engineered fill must extend over the entire graded area; the engineered fill

envelope and finished elevations must be clearly and accurately defined in the

field, and must be precisely documented by qualified surveyors. Foundations

partially on engineered fill must be reinforced by two 15-mm steel reinforcing

bars in the footings and upper section of the foundation walls, or be designed by


a structural engineer to properly distribute the stress induced by the abrupt

differential settlement (about 15 mm) between the natural soil and engineered

fill.

8. Foundations partially on engineered fill must be reinforced by two 15-mm steel

reinforcing bars in the footings and upper section of the foundation walls, or be

designed by a structural engineer to properly distribute the stress induced by the

abrupt differential settlement (about 15 mm) between the natural soil and

engineered fill.

9. The engineered fill must not be placed during the period from late November to

early April when freezing ambient temperatures occur either persistently or

intermittently. This is to ensure that the fill is free of frozen soils, ice and snow.

10. Where the fill is to be placed on a bank steeper than 1 vertical:3 horizontal, the

face of the bank must be flattened to 3 + so that it is suitable for safe operation

of the compactor and the required compaction can be obtained.

11. Where the ground is wet due to subsurface water seepage, an appropriate

subdrain scheme must be implemented prior to the fill placement, particularly if

it is to be carried out on sloping ground.

12. The fill operation must be inspected on a full-time basis by a technician under

the direction of a geotechnical engineer.

13. The footing and underground services subgrade must be inspected by the

geotechnical consulting firm that supervised the engineered fill placement. This

is to ensure that the foundations are placed within the engineered fill envelope,

and the integrity of the fill has not been compromised by interim construction,

environmental degradation and/or disturbance by the footing excavation.

14. Any excavation carried out in certified engineered fill must be reported to the

geotechnical consultant who supervised the fill placement in order to document

the locations of excavation and/or to supervise reinstatement of the excavated

areas to engineered fill status. If construction on the engineered fill does not


commence within a period of 2 years from the date of certification, the

condition of the engineered fill must be assessed for re-certification.

15. Despite stringent control in the placement of the engineered fill, variations in

soil type and density may occur in the engineered fill. Therefore, the strip

footings and the upper section of the foundation walls constructed on the

engineered fill may require continuous reinforcement with steel bars, depending

on the uniformity of the soils in the engineered fill and the thickness of the

engineered fill underlying the foundations. Should the footings and/or walls

require reinforcement, the required number and size of reinforcing bars must be

assessed by considering the uniformity as well as the thickness of the

engineered fill beneath the foundations. In sewer construction, the engineered

fill is considered to have the same structural proficiency as a natural inorganic

soil.

6.3 Underground Structure and Slab-on-Grade

The perimeter walls of underground structures should be designed to sustain a lateral

earth pressure calculated using the soil parameters given in Table 5 in this report.

Any applicable surcharge loads adjacent to the proposed building must also be

considered in the design of the underground structures.

The subgrade for slab-on-grade construction must consist of sound natural soils or

properly compacted inorganic earth fill. In preparation of the subgrade, it must be

inspected and assessed by proof-rolling. Any soft soils should be subexcavated,

sorted free of any deleterious material, aerated and uniformly compacted to 98% or +

of its maximum Standard Proctor dry density. If the deleterious materials cannot be

sorted, the soils should be replaced by properly compacted, organic-free earth fill.


The slab should be constructed on a granular base, 20 cm thick, consisting of

20-mm Crusher-Run Limestone, or equivalent, compacted to its maximum Standard

Proctor dry density. A Modulus of Subgrade Reaction of 25 MPa/m can be used for

the design of the floor slab.

The slab-on-grade in open areas should be designed to tolerate frost heave and the

grading around the slab-on-grade and building structures must be such that it directs

runoff away from the structures.

6.4 Underground Services

The subgrade for the underground services should consist of sound natural soil or

properly compacted inorganic earth fill. Where organics or badly weathered soils are

encountered, it should be subexcavated and replaced with the bedding material,

compacted to at least 95% or + of its Standard Proctor compaction.

A Class ‘B’ bedding is recommended for construction of the underground services.

The bedding material should consist of compacted 20-mm Crusher-Run Limestone,

or equivalent, to be approved by a geotechnical engineer.

The pipes must be connected by leak-proof joints, or the joints should be wrapped

with a waterproof membrane, to prevent subgrade upfiltration through the joints.

In order to prevent pipe floatation when the sewer trench is deluged with water, a soil

cover with a thickness equal to the diameter of the pipe should be in place at all times

after completion of the pipe installation.


Openings to subdrains and catch basins should be shielded with a fabric filter to

prevent blockage by silting.

The subgrade soils of the underground services have a moderately high corrosivity to

buried metal. These soils are considered corrosive to ductile iron pipes and metal

fittings; therefore, the underground services should be protected against soil

corrosion. For estimation of anode weight requirements, the estimated electrical

resistivity of 2500 ohm⋅cm can be used. This, however, should be confirmed by

testing the soil along the trench at the time of construction.

6.5 Backfilling in Trenches and Excavated Areas

The on site inorganic soils are generally suitable for use as trench backfill. However,

the soils should be sorted free of any topsoil inclusions and other deleterious

materials prior to the backfilling. Oversized boulders (over 15 cm in size) must be

segregated and removed from the backfill.

The backfill in the trenches should be compacted to at least 95% of its maximum

Standard Proctor dry density. In the zone within 1.0 m below the road subgrade, the

materials should be compacted with the water content 2% to 3% drier than the

optimum, and the compaction should be increased to at least 98% of the respective

maximum Standard Proctor dry density. This is to provide the required stiffness for

pavement construction. In the lower zone, the compaction should be carried out on

the wet side of the optimum; this allows a wider latitude of lift thickness. Backfill

below any slab-on-grade which is sensitive to settlement must be compacted to at

least 98% of its maximum Standard Proctor dry density.


In normal construction practice, the problem areas of settlement largely occur

adjacent to manholes, catch basins, service crossings, foundation walls and columns.

In areas which are inaccessible to a heavy compactor, imported sand backfill should

be used. Unless compaction of the backfill is carefully performed, the interface of the

native soils and the sand backfill will have to be flooded for a period of several days.

The narrow trenches for services crossings should be cut at 1 vertical:

2 or + horizontal so that the backfill can be effectively compacted. Otherwise, soil

arching will prevent the achievement of proper compaction. The lift of each backfill

layer should either be limited to a thickness of 20 cm, or the thickness should be

determined by test strips.

One must be aware of the possible consequences during trench backfilling and

exercise caution as described below:

• When construction is carried out in freezing winter weather, allowance should

be made for these following conditions. Despite stringent backfill monitoring,

frozen soil layers may inadvertently be mixed with the structural trench backfill.

Should the in situ soils have a water content on the dry side of the optimum, it

would be impossible to wet the soils due to the freezing condition, rendering

difficulties in obtaining uniform and proper compaction. Furthermore, the

freezing condition will prevent flooding of the backfill when it is required, such

as in a narrow vertical trench section, or when the trench box is removed. The

above will invariably cause backfill settlement that may become evident within

1 to several years, depending on the depth of the trench which has been

backfilled.

• In areas where the underground services construction is carried out during the

winter months, prolonged exposure of the trench walls will result in frost heave

within the soil mantle of the walls. This may result in some settlement as the


frost recedes, and repair costs will be incurred prior to final surfacing of the new

pavement and the slab-on-grade.

• To backfill a deep trench, one must be aware that future settlement is to be

expected, unless the side of the cut is flattened to at least 1 vertical:

1.5+ horizontal, and the lifts of the fill and its moisture content are stringently

controlled; i.e., lifts should be no more than 20 cm (or less if the backfilling

conditions dictate) and uniformly compacted to achieve at least 95% of the

maximum Standard Proctor dry density, with the moisture content on the wet

side of the optimum.

• It is often difficult to achieve uniform compaction of the backfill in the lower

vertical section of a trench which is an open cut or is stabilized by a trench box,

particularly in the sector close to the trench walls or the sides of the box. These

sectors must be backfilled with sand. In a trench stabilized by a trench box, the

void left after the removal of the box will be filled by the backfill. It is

necessary to backfill this sector with sand, and the compacted backfill must be

flooded for 1 day, prior to the placement of the backfill above this sector, i.e., in

the upper sloped trench section. This measure is necessary in order to prevent

consolidation of inadvertent voids and loose backfill which will compromise the

compaction of the backfill in the upper section. In areas where groundwater

movement is expected in the sand fill mantle, anti-seepage collars should be

provided.

6.6 Pavement Design

The recommended pavement design for a local residential road and collector is

presented in Table 4.


Table 4 - Pavement Design

Course Thickness (mm) OPS Specifications

Asphalt Surface 40 HL-3

Asphalt Binder - Local Road - Collectors

50 65

HL-8

Granular Base 150 Granular ‘A’ or equivalent

Granular Sub-base - Local Road - Collectors

300 450

Granular ‘B’ or equivalent

In preparation of the subgrade, the topsoil and ploughed earth should be stripped and

removed, and the subgrade surface must be proof-rolled. Any earth fill used to raise

the grade for pavement construction should consist of organic-free soil uniformly

compacted to 98% or + of its maximum Standard Proctor dry density.

All the granular bases should be compacted to 100% of their maximum Standard

Proctor dry density.

In the zone within 1.0 m below the road subgrade, the backfill should be compacted

to at least 98% of its maximum Standard Proctor dry density, with the water content

2% to 3% drier than the optimum. In the lower zone, a 95% or + Standard Proctor

compaction is considered adequate.

The road subgrade will suffer a strength regression if water is allowed to saturate the

mantle. The following measures should, therefore, be incorporated into the

construction procedures and pavement design:


• If the road construction does not immediately follow the trench backfilling, the

subgrade should be properly crowned and smooth-rolled to allow interim

precipitation to be properly drained.

• Lot areas adjacent to the roads should be properly graded to prevent ponding

of large amounts of water during the interim construction period.

• Curb subdrains will be required. They should consist of filter-sleeved weepers

to prevent blockage by silting and connecting to a positive outlet.

• If the roads are to be constructed during wet seasons and extensively soft

subgrade occurs, the granular sub-base should be thickened in order to

compensate for the inadequate strength of the subgrade. This can be assessed

during construction.

6.7 Soil Parameters

The recommended soil parameters for the project design are given in Table 5.

Table 5 - Soil Parameters

Unit Weight and Bulk Factor Unit Weight (kN/m3)

Estimated Bulk Factor

Bulk Submerged Loose Compacted

Existing Earth Fill 21.0 11.0 1.30 0.98

Silty Clay Till 22.0 12.0 1.30 1.05

Sandy Silt Till 22.5 12.5 1.30 1.05

Lateral Earth Pressure Coefficients Active Ka

At Rest K0

Passive Kp

Compacted Earth Fill 0.40 0.60 2.50

Silty Clay Till 0.35 0.50 3.00

Sandy Silt Till 0.30 0.45 3.30


6.8 Excavation

Excavation should be carried out in accordance with Ontario Regulation 213/91. For

excavation purposes, the types of soils are classified in Table 6.

Table 6 - Classification of Soils for Excavation Material Type

Sound Tills 2

Existing Earth Fill 3

Excavation into the tills containing boulders will require extra effort and the use of a

heavy-duty, properly equipped backhoe. Boulders larger than 15 cm in size are not

suitable for use in structural backfill and/or construction of engineered fill.

In excavation, any groundwater yield is expected to be slow in rate and limited in

quantity. It can be drained to a sump pit and removed by conventional pumping.

Prospective contractors must be asked to assess the in situ subsurface conditions for

soil cuts and to assess the proper method for groundwater control by test pits. They

must be dug to at least 0.5 m below the intended bottom of excavation prior to and/or

during project construction. These test pits should be allowed to remain open for a

period of at least 4 hours to assess the trenching conditions.

LIST OF ABBREVIATIONS AND DESCRIPTION OF TERMS The abbreviations and terms commonly employed on the borehole logs and figures, and in the text of the report, are as follows: SAMPLE TYPES

AS Auger sample CS Chunk sample DO Drive open (split spoon) DS Denison type sample FS Foil sample RC Rock core (with size and percentage

recovery) ST Slotted tube TO Thin-walled, open TP Thin-walled, piston WS Wash sample PENETRATION RESISTANCE

Dynamic Cone Penetration Resistance:

A continuous profile showing the number of blows for each foot of penetration of a 2-inch diameter, 90° point cone driven by a 140-pound hammer falling 30 inches. Plotted as ‘ • ’

Standard Penetration Resistance or ‘N’ Value:

The number of blows of a 140-pound hammer falling 30 inches required to advance a 2-inch O.D. drive open sampler one foot into undisturbed soil. Plotted as ‘’

WH Sampler advanced by static weight PH Sampler advanced by hydraulic pressure PM Sampler advanced by manual pressure NP No penetration

SOIL DESCRIPTION

Cohesionless Soils:

‘N’ (blows/ft) Relative Density

0 to 4 very loose 4 to 10 loose

10 to 30 compact 30 to 50 dense

over 50 very dense

Cohesive Soils:

Undrained Shear Strength (ksf) ‘N’ (blows/ft) Consistency

less than 0.25 0 to 2 very soft 0.25 to 0.50 2 to 4 soft 0.50 to 1.0 4 to 8 firm 1.0 to 2.0 8 to 16 stiff 2.0 to 4.0 16 to 32 very stiff

over 4.0 over 32 hard

Method of Determination of Undrained Shear Strength of Cohesive Soils:

x 0.0 Field vane test in borehole; the number denotes the sensitivity to remoulding

Laboratory vane test

Compression test in laboratory

For a saturated cohesive soil, the undrained shear strength is taken as one half of the undrained compressive strength

METRIC CONVERSION FACTORS 1 ft = 0.3048 metres 1 inch = 25.4 mm 1lb = 0.454 kg 1ksf = 47.88 kPa

192.1

188.0

186.4

0.0

0.5

4.6

6.2 END OF BOREHOLE

PLOUGHED EARTH brown sandy silt, some clay a trace of gravel occ. cobbles and topsoil inclusionsBrown to reddish brown, hard

SILTY CLAY TILL trace gravel and sand occ. sand seams and layers, cobbles and boulders

Reddish brown, very dense

SANDY SILT TILL trace gravel and clay occ. cobbles and boulders

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

7

45

38

43

53

50/13

50/8

8

7

6

5

4

3

2

1

0 20

11

16

14

10

9

8

Dry

on

com

plet

ion

1LOG OF BOREHOLE NO.:1806-S145JOB NO.:

Proposed Residential DevelopmentPROJECT DESCRIPTION:

Britannia Road and Thompson Road South Town of Milton

PROJECT LOCATION:

1FIGURE NO.:

Flight-AugerMETHOD OF BORING:

July 24, 2018DRILLING DATE:

192.6 Ground Surface

El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)

Atterberg LimitsPL LL

WAT

ER L

EVEL

Dynamic Cone (blows/30 cm)

9070503010

Penetration Resistance(blows/30 cm)

9070503010

Shear Strength (kN/m2)

20015010050

Moisture Content (%)40302010

Soil Engineers Ltd.1 of 1Page:

191.6

190.7

185.9

0.0

0.5

1.4

6.2 END OF BOREHOLE

PLOUGHED EARTH brown silty clay, a trace of gravel occ. topsoil inclusionBrown, very stiff

SILTY CLAY TILL trace gravel and sand occ. sand seams and layers, cobbles and bouldersBrown to reddish brown, very dense

SANDY SILT TILL trace gravel and clay occ. sand seams and layers, cobbles and boulders some rock fragments

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

9

29

60

81

50/13

50/15

50/8

8

7

6

5

4

3

2

1

0 21

13

10

11

8

8

5

Dry

on

com

plet

ion




PROJECT LOCATION:

2FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



191.2

189.5

185.4

0.0

0.4

2.1

6.2 END OF BOREHOLE

PLOUGHED EARTH brown silty clay, with inclusion of topsoil and rootletsBrown, hard


Brown to reddish brown, very dense

SANDY SILT TILL trace gravel and clay occ. sand seams and layers, cobbles and boulders

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

13

34

48

64

50/13

50/10

50/8

8

7

6

5

4

3

2

1

0 15

13

11

8

7

7

10

Dry

on

com

plet

ion




PROJECT LOCATION:

3FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



191.5

188.0

185.8

0.0

0.5

4.0

6.2 END OF BOREHOLE

PLOUGHED EARTH brown silty clay, a trace of gravelBrown/reddish brown, hard


Reddish brown, very dense

SANDY SILT TILL trace gravel and clay occ. sand seams and layers, cobbles and boulders shale fragments at 4.6 m

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

13

38

46

43

47

50/13

50/10

8

7

6

5

4

3

2

1

0 19

14

13

12

12

10

7

Dry

on

com

plet

ion




PROJECT LOCATION:

4FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



190.6

188.3

184.9

0.0

0.5

2.8

6.2 END OF BOREHOLE

PLOUGHED EARTH brown silty clay, a trace of gravelBrown to reddish brown, hard


Brown, very dense

SANDY SILT TILL trace gravel and clay occ. sand seams and silty sand layers, cobbles and boulders

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

8

35

32

62

50/13

50/13

50/13

8

7

6

5

4

3

2

1

0 24

15

15

11

9

9

8

W.L

@ E

l. 18

5.2

m o

n co

mpl

etio

n




PROJECT LOCATION:

5FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



190.6

188.1

184.5

0.0

0.3

2.8

6.4

END OF BOREHOLE

PLOUGHED SOILReddish brown, hard

SILTY CLAY TILL trace gravel and sand occ. sand seams and layers, cobbles and boulders occ. sand pockets

Very dense

SANDY SILT TILL trace gravel and clay occ. sand seams and layers, cobbles and boulders

reddish brown

grey

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

14

36

38

45

60

50/10

50/13

8

7

6

5

4

3

2

1

0 17

13

12

11

11

9

10

Dry

on

com

plet

ion




PROJECT LOCATION:

6FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



190.6

190.1

186.9

185.0

0.0

0.6

1.1

4.3

6.2 END OF BOREHOLE

PLOUGHED EARTH brown silty clay, a trace of gravel

EARTH FILL brown silty clay, some brick fragments, occ. topsoil inclusionsBrown, hard


Brown, very dense

SANDY SILT TILL trace gravel and clay occ. cobbles and boulders occ. shale fragments

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

15

24

40

50/15

80/30

50/13

50/15

8

7

6

5

4

3

2

1

0 23

19

14

11

10

9

7

W.L

@ E

l. 18

5.8

m o

n co

mpl

etio

n




PROJECT LOCATION:

7FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



191.7

186.6

185.8

0.0

0.5

5.6

6.4

END OF BOREHOLE

PLOUGHED EARTH brown silty clay, a trace of gravelBrown, hard


Brown to greyish brown, very dense


1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

13

42

52

56

55

57

50/15

8

7

6

5

4

3

2

1

0 23

13

14

12

11

11

11

Dry

on

com

plet

ion




PROJECT LOCATION:

8FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



185.1

184.3

0.0

0.3

5.6

6.4

END OF BOREHOLE

PLOUGHED EARTH brown silty clay, a trace of gravelBrown to reddish brown, very stiff to hard


Grey, very dense


1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

19

24

37

42

37

57

50/10

8

7

6

5

4

3

2

1

0 20

15

17

14

14

12

8

Dry

on

com

plet

ion




PROJECT LOCATION:

9FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



190.9

185.9

185.1

0.0

0.6

5.6

6.4

END OF BOREHOLE

PLOUGHED EARTH brown silty clay and sandy silt, a trace of gravelHard


Grey, very dense

SANDY SILT TILL trace gravel and clay occ. layers of fine to medium sand, cobbles and boulders occ. shale fragments

browngrey

1

2

3

4

5

6

7

DO

DO

DO

DO

DO

DO

DO

8

30

48

60

81

52

50/13

8

7

6

5

4

3

2

1

0 19

13

13

12

12

10

9

Dry

on

com

plet

ion




PROJECT LOCATION:

10FIGURE NO.:




El.(m)

Depth(m)

SOILDESCRIPTION

SAMPLES

Num

ber

Type

N-V

alue

Dep

th S

cale

(m)


WAT

ER L

EVEL


9070503010


9070503010


20015010050



Reference No: 1806-S145

U.S. BUREAU OF SOILS CLASSIFICATION

COARSE

UNIFIED SOIL CLASSIFICATION

COARSE

Project: Proposed Residential Development BH./Sa. 4/5 6/3 10/4

Location: Britannia Road West and Thompson Road South, Town of Milton Liquid Limit (%) = - 29 -

Plastic Limit (%) = - 17 -

Borehole No: 4 6 10 Plasticity Index (%) = - 12 -

Sample No: 5 3 4 Moisture Content (%) = 12 - 12

Depth (m): 3.3 1.8 2.5 Estimated Permeability

Elevation (m): 188.7 189.1 189.0 (cm./sec.) = 10-7 10-7 10-7

Classification of Sample [& Group Symbol]: SILTY CLAY TIL, some sand to sandy, a trace of gravel

GRAIN SIZE DISTRIBUTION

SAND

V. FINE

GRAVELSILT

COARSE FINEFINE

SILT & CLAY

Figure: 11

COARSE

MEDIUM

FINE

CLAY

SAND

MEDIUMFINE

GRAVEL

3" 2-1/2" 2" 1-1/2" 1" 3/4" 1/2" 3/8" 4 8 10 16 20 30 40 50 60 100 140 200 270 325

0

10

20

30

40

50

60

70

80

90

100

0.0010.010.1110100

Perc

ent P

assi

ng

Grain Size in millimeters

BH.6/Sa.3

BH.10/Sa.4

BH.4/Sa.5

90 WEST BEAVER CREEK, SUITE #100, RICHMOND HILL, ONTARIO L4B 1E7 · TEL: (416) 754-8515 · FAX: (905) 881-8335

Soil Engineers Ltd.CONSULTING ENGINEERS

GEOTECHNICAL | ENVIRONMENTAL | HYDROGEOLOGICAL | BUILDING SCIENCE

SITE:

DESIGNED BY: CHECKED BY: DWG NO.:

SCALE: REF. NO.: DATE:

REV

BOREHOLE LOCATION PLAN

N.A B.L

Britannia Road W and Thompson Road S, Milton

1

1:4000 1806-S145 August 2018

192

191

190

189

188

187

186

185

184

183

182

181

192

191

190

189

188

187

186

185

184

183

182

181

7

45

38

43

53

50/13

50/8

9

29

60

81

50/13

50/15

50/8

13

34

48

64

50/13

50/10

50/8

13

38

46

43

47

50/13

50/10

8

35

32

62

50/13

50/13

50/13

14

36

38

45

60

50/10

50/13

15

24

40

50/15

80/30

50/13

50/15

13

42

52

56

55

57

50/15

19

24

37

42

37

57

50/10

8

30

48

60

81

52

50/13

Soil Engineers Ltd.CONSULTING ENGINEERSGEOTECHNICAL | ENVIRONMENTAL | HYDROGEOLOGICAL | BUILDING SCIENCE

SUBSURFACE PROFILEDRAWING NO. 2

SCALE: AS SHOWN

JOB NO.: 1806-S145REPORT DATE: August 2018PROJECT DESCRIPTION: Proposed Residential Development

PROJECT LOCATION: Britannia Road and Thompson Road South Town of Milton

LEGENDPLOUGHED EARTH FILL SANDY SILT TILL SILTY CLAY TILL

WATER LEVEL (END OF DRILLING) CAVE-IN 1

192.62

192.13

191.64

1925

191.16

190.97

191.28

192.29

190.710

191.5BH No.:El. (m):

Documents

A REPORT TO MIL CON THREE DEVELOPMENTS LIMITED A ... · A REPORT TO MIL CON THREE DEVELOPMENTS LIMITED A GEOTECHNICAL INVESTIGATION FOR PROPOSED RESIDENTIAL DEVELOPMENT BRITANNIA