Geotechnical Evaluation - Bridge Replacement€¦ · 5.2.1 Limit States Design ... The rig was equipped with 150 mm diameter solid stem continuous ... GEOTECHNICAL EVALUATION –

Tetra Tech EBA Inc.Riverbend Atrium One, 115, 200 Rivercrest Drive SE

Calgary, AB T2C 2X5 CANADA

Tel 403.203.3355 Fax 403.203.3301

PRESENTED TO

Roseke Engineering Ltd.

GEOTECHNICAL EVALUATIONBRIDGE REPLACEMENT (BRIDGE FILE 1174)LSD 2-13-31-27-W4MNEAR DIDSBURY, ALBERTA

SEPTEMBER 2014

ISSUED FOR USE

FILE: L12103641-01

Geotechnical Evaluation - Bridge Replacement.docx

This page intentionally left blank.

GEOTECHNICAL EVALUATION – BRIDGE REPLACEMENT (BRIDGE FILE 1174)

FILE: L12103641-01 | SEPTEMBER 2014 | ISSUED FOR USE

i


TABLE OF CONTENTS

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

2.0 PROJECT DETAILS AND SCOPE OF WORK ............................................................................ 1

3.0 GEOTECHNICAL FIELD AND LABORATORY WORK............................................................... 1

4.0 SITE AND SUBSURFACE CONDITIONS.................................................................................... 2

4.1 Site Conditions.......................................................................................................................................2

4.2 Soil Conditions .......................................................................................................................................2

4.3 Groundwater Conditions ........................................................................................................................2

5.0 GEOTECHNICAL RECOMMENDATIONS................................................................................... 3

5.1 General ..................................................................................................................................................3

5.2 Foundations ...........................................................................................................................................4

5.2.1 Limit States Design [LSD].........................................................................................................4

5.2.2 Design Backfill Soil Parameters................................................................................................4

5.2.3 Driven Steel Piles .....................................................................................................................5

5.2.4 Bored Cast-in-Place [CIP] Piles................................................................................................6

5.2.5 Lateral Pile Loading ..................................................................................................................7

5.2.6 Excavation and Backfill .............................................................................................................8

5.2.7 Seismic Factors ........................................................................................................................9

5.2.8 Concrete Type ..........................................................................................................................9

6.0 DESIGN AND CONSTRUCTION GUIDELINES........................................................................... 9

7.0 CLOSURE.................................................................................................................................. 11

LIST OF TABLES IN TEXT

Table 4.3: Groundwater Monitoring Data ............................................................................................... 3

Table 5.2.1: Soil Resistance Factors...................................................................................................... 4

Table 5.2.2: General Design Parameters for Cohesive Engineered Fill* ................................................ 5

Table 5.2.3: Axial Driven Steel Pile Design Parameters......................................................................... 5

Table 5.2.4: Bored Cast-in-Place Pile Design Parameters ..................................................................... 6

FIGURES

Figure 1 Borehole Location Plan



ii


APPENDIX SECTIONS

APPENDICES

Appendix A

Appendix B

Appendix C

Appendix D

Appendix E

Tetra Tech’s General Conditions

Soil Description Guideline and Borehole Logs

Construction Guidelines

Laboratory Results

Selection of Site Photos



iii


LIMITATIONS OF REPORT

This report and its contents are intended for the sole use of Roseke Engineering Ltd. and their agents. Tetra Tech EBA Inc.

(Tetra Tech EBA) does not accept any responsibility for the accuracy of any of the data, the analysis, or the recommendations

contained or referenced in the report when the report is used or relied upon by any Party other than Roseke Engineering Ltd., or

for any Project other than the proposed development at the subject site. Any such unauthorized use of this report is at the sole

risk of the user. Use of this report is subject to the terms and conditions stated in Tetra Tech EBA’s Services Agreement. Tetra

Tech EBA’s General Conditions are provided in Appendix A of this report.



1


1.0 INTRODUCTION

This report presents the results of a geotechnical evaluation conducted by Tetra Tech EBA Inc. (Tetra Tech EBA)

for the proposed Bridge Replacement (Bridge File 1174) project, located east of the Town of Didsbury, Alberta.

The legal description of the site is LSD 2-13-31-27 W4M.

The scope of work for this evaluation was outlined in a proposal emailed to Mr. Bernie Roseke, of Roseke

Engineering Ltd. (REL), on July 8, 2014. The objective of this work was to determine the general subsurface

conditions in the area of the proposed site and develop recommendations for the geotechnical aspects of design

and construction for the proposed structure.

Authorization to proceed with the work was provided by Mr. Roseke, of REL, with a signed services agreement on

July 8, 2014.

2.0 PROJECT DETAILS AND SCOPE OF WORK

Based on the information provided by REL, the existing bridge structure, located at Bridge File 1174, is to be

replaced. Through discussions with REL, it is understood that the preferred foundation structure would be a deep

foundation system with pile options, including cast-in-place (CIP) concrete piles, driven steel piles, or driven

wooden piles.

The work scope comprised the boring of two geotechnical boreholes, a laboratory program to assist in classifying

the subsurface soils and a report providing foundation design and construction recommendations for design

consideration of the proposed structure.

3.0 GEOTECHNICAL FIELD AND LABORATORY WORK

The fieldwork for this evaluation was carried out on July 23, 201, using a truck-mounted drill rig contracted from

Earth Drilling Co. Ltd. of Calgary, Alberta. The rig was equipped with 150 mm diameter solid stem continuous

flight augers. Tetra Tech EBA’s field representative for the duration of the project was Mr. Kyle Haugrud, P.Eng.

Two boreholes (BH A - west and BH B - east) were bored on the existing road surface, near each end of the

bridge, extending to depths of 15.0 m. Borehole BH A (west) was bored approximately 19 m west of the bridge

deck and borehole BH B (east) was bored approximately 23 m east. The borehole locations were laid out by the

Tetra Tech EBA field representative on site and were surveyed with a handheld GPS. The borehole locations are

presented in plan view on Figure 1. A selection of photos of the drilling locations is provided in Appendix E.

Disturbed grab samples were obtained within each borehole at approximate 1.5 m intervals. In addition, Standard

Penetration Tests (SPTs) were performed at depth intervals of 1.5 m down to the approximate water table

elevation. Past this point, significant sloughing prohibited the effective transition between solid stem boring and

SPT; therefore, the SPTs were performed continuously over 3.0 m intervals and recorded at depth intervals of

0.5 m. Following the SPT, the 3.0 m interval would be bored for sampling and visual classification. All soil

samples were visually classified in the field, and the individual soil strata and the interfaces between them were

noted. The borehole logs are presented in Appendix B. An explanation of the terms and symbols used on the

borehole logs is also included in Appendix B.

Slotted 25 mm diameter PVC standpipes were installed in each borehole to monitor groundwater levels. Auger

cuttings were used to backfill around the standpipes and they were sealed at surface with bentonite chips.



2


Classification tests including natural moisture content, Atterberg limits, grain size analysis and soluble sulphate

determination were subsequently performed on the collected borehole samples at Tetra Tech EBA’s laboratory in

Calgary to aid in the determination of engineering properties. Laboratory results are provided in Appendix D.

4.0 SITE AND SUBSURFACE CONDITIONS

4.1 Site Conditions

The proposed bridge crossing site is located to the east of the Town of Didsbury, Alberta. The river channel bed

at the crossing location runs from the northeast to the southwest and is approximately 4.5 m lower than the

existing roadway surface. A selection of photos of the site is provided in Appendix E.

4.2 Soil Conditions

Specific details of the stratigraphy encountered at each borehole are presented on the borehole logs in Appendix

B and are discussed in the following subsections of this report. It should be noted that geological conditions are

innately variable. Glacial deposits, in particular, are seldom spatially uniform. At the time of preparation of this

report, information on subsurface stratigraphy is available only at discrete borehole locations. Adequate

monitoring is required during construction to check that these assumptions are reasonable.

The general subsurface conditions encountered at the boreholes included surficial layers of sand/clay fill/clay till,

underlain by sand and clay till.

Sandy clay fill/clayey sand fill was encountered as surficial soil at the borehole locations, extending up to depths

of approximately 3.0 m, described as firm in consistency (road embankment fill). A layer of stiff clay till was noted

directly underlying the fill layer. Results of Atterberg Limit tests conducted on samples taken at the higher fine

zones specified a plastic limit of 13% (for both samples) and liquid limits of 22% and 26%, signifying a low

plasticity clay.

Beneath the apparent fill and clay till was sand with a low percentage of fines, in the upper zone, and compact to

dense. Sieve analysis of this zone indicated it was comprised of 94.7% granular material and 5.3% fines. As the

boreholes increased in depth so did the percentage of fines and the relative density improved to very dense.

Sieve analysis results near the bottom of the boreholes exhibited the following material proportions; 2% gravel,

53% sand, 27% silt, and 18% clay.

4.3 Groundwater Conditions

At the time of drilling, seepage and sloughing was encountered within the sand at both borehole locations.

The groundwater level was measured on August 8, 2014. The following table summarizes the groundwater

monitoring data:



3


Table 4.3: Groundwater Monitoring Data

Borehole

Number

Depth of Standpipe(m)

Approximate Distancefrom Bridge Deck (m)

Depth to Groundwater (m)

August 8, 2014

BH A (WEST) 9.39 19 4.19

BH B (EAST) 12.18 23 4.26

The groundwater levels at the borehole locations are considered to represent groundwater perched within the

granular layer and normally fluctuate seasonally, in response to climatic conditions and river surface water levels.

Further comments regarding groundwater issues are provided in the subsequent sections.

5.0 GEOTECHNICAL RECOMMENDATIONS

5.1 General

The following presents geotechnical recommendations for the design of the proposed bridge crossing structure

foundations. As discussed in this report, the subgrade is comprised of sand and clay fill soils, with clay till near

surface, underlain by granular material. Based on the site and soil conditions, the preferred foundation system

recommended is a deep foundation system.

The groundwater level within the granular stratum appears to be approximately 4.3 m below ground surface.

Variable amounts of groundwater seepage should be expected for any excavations to this level and for

construction of drilled piles.

Driven steel piles are typically used for many bridge structures in Alberta and are recommended as the preferred

foundation option for this project. Relatively high axial capacities are available, provided the piles are driven to

the underlying granular layers and/or to hard refusal. Pipe piles may be considered for lateral loading conditions if

desirable to avoid considering lower capacities in the weak axis of the H-piles. Testing using a Pile Driving

Analyzer (PDA) is recommended during production piling to provide a more accurate assessment of the available

ultimate geotechnical axial pile capacities. A potential issue with pile installation would be the possibility of

encountering cobbles and/or boulders in the granular which would potentially limit pile penetration. In the event of

early refusal, predrilling may be required if deeper pile penetration is deemed necessary due to structural loading

conditions.

Bored CIP concrete piles may also be considered as an alternative foundation option for this project. However,

casing should be expected to prevent groundwater seepage and sloughing of the pile bore, which will increase

foundation costs. The use of a continuous flight auger method is recommended as a feasible alternative.

Recommendations for design and construction of bored CIP piles are provided.

Shallow footings have been considered; however, for this project are not preferred. If given consideration, a

shallow foundation system would need to be founded at a suitable depth for frost protection and erosion

protection, with adequate lateral capacity from surrounding subgrade soils and/or adjacent canal embankment

soils. Cofferdam structures will be needed for footings to be constructed within or adjacent to the river channel.

Detailed axial and lateral structural loading requirements are needed to evaluate the site-specific geotechnical

suitability of this foundation option and beyond the work scope of this evaluation. Tetra Tech EBA would need to

perform further analysis to develop shallow footing design if this option is deemed necessary. Recommendations

for footing foundations may be provided upon request.



4


Driven timber piles have also been considered, but are no longer in common use in Alberta, so recommendations

can be provided up request. Dynamically cast-in-place concrete piles have also been considered. Though

technically suitable for these soil conditions, delivery of concrete to the site is deemed problematic and

mobilization costs may make this option less economical. Recommendations can be provided upon request.

All foundation design recommendations presented in this report are based on the assumption that an adequate

level of construction monitoring during foundation installation will be provided and that all construction will be

carried out by a suitably qualified/experienced contractor. An adequate level of construction monitoring is

considered to be full-time monitoring and design review during construction for deep foundations. Suitably

qualified personnel should carry out all such monitoring. One of the purposes of providing an adequate level of

monitoring is to check that the recommendations, based on data obtained at discrete borehole locations, are

relevant to other areas of the site.

5.2 Foundations

5.2.1 Limit States Design

The design parameters provided in the following sections may be utilized to calculate the ultimate foundation

capacity in each case. For the Limit States Design (LSD) methodology, in order to calculate the factored load

capacity, the appropriate Soil Resistance Factors must be applied to each loading condition, as noted below.

These factors are considered to be in accordance with the Canadian Foundation Engineering Manual (2006) and

the National Building Code of Canada (2010).

Table 5.2.1: Soil Resistance Factors

Deep Foundations

Compressive Capacity

From semi-empirical analysis 0.4

From dynamic monitoring

(i.e., PDA testing)0.5

From static load test results 0.6

Lateral Resistance From semi-empirical analysis 0.5

Uplift ResistanceFrom semi-empirical analysis 0.3

From load test results 0.4

5.2.2 Design Backfill Soil Parameters

The design soil parameters to be considered in various aspects of the foundation design are provided as follows.

If the fill soils are different from the local clay till soils used in the road embankment fill, Tetra Tech EBA should be

contacted when using the design soil parameters in Table 5.2.2.



5


Table 5.2.2: General Design Parameters for Cohesive Engineered Fill*

Parameter Recommended Value

Bulk Unit Weight of Clay (γ) 18 kN/m³

Friction Angle of Clay (φ) 25°

Interaction of Clay and Concrete 20°

Undrained Shear Strength (Cu) 70 kPa

Active Earth Pressure Coefficient (Ka) 0.4

At Rest Earth Pressure Coefficient (Ko) 0.50

Passive Earth Pressure Coefficient (Kp) 2.5

* Cohesive engineered fill compacted to at least 98% of Standard Proctor Density (SPD).

5.2.3 Driven Steel Piles

Ultimate skin friction and end-bearing parameters for driven piles supporting axial compressive loads are

presented as follows. The geotechnical resistance factors recommended in Section 5.2.1 should be considered

to calculate the Ultimate Limits State (ULS) factored values of shaft and base resistances. The ultimate capacity

of driven steel piles in the native soils may be determined from the following equation:

Q = rsAsD + rtAt.

Where:

Q = Ultimate load capacity of the pile (kN).

rs = Ultimate skin friction between the pile and soil (kPa).

As = Minimum perimeter of pile section per unit length of pile (m2).

D = Effective length of pile embedment (m).

rt = Ultimate end-bearing (kPa).

At = Gross cross-sectional area of the pile tip (m2).

Piles may be designed to resist axial loads on the basis of the ultimate end-bearing resistance and skin friction

resistances provided in Table 5.2.3.

Table 5.2.3: Axial Driven Steel Pile Design Parameters

Elevation (Geodetic Datum)(m)

Ultimate Skin Friction(kPa)

Ultimate End-Bearing(kPa)

Above 3.0 m depth

(Sandy Clay/Clayey Sand Fill)0 N/A

>3.0 m (Granular Material) 60 2,000



6


For steel pipe piles that are not predrilled, the total exterior surface area (outer perimeter only) of the pile should

be used in calculating the load capacity. For steel H-piles that are not predrilled, the surface area (As) and gross

cross-sectional area (At) to be used for design should be represented by the exterior rectangular plugged

dimension of the pile section. It is assumed open-ended pipe piles will plug and the design end-bearing may be

adopted plus the shaft friction of the pile exterior. Should preboring be required, the diameter of prebore should

not be more than 90% of the size of the pile section with no effects for driven steel pipe piles. In the case of

preboring for driven H-pile sections, the load capacity of the pile should be reviewed by a geotechnical engineer.

For piles placed in pile groups, provided the piles are placed no closer than 2.5 pile diameters apart, reductions in

pile capacity due to group effects need not be considered (Section 6.8.9.2, 2006 Canadian Bridge Design Code).

Closely spaced pile groups should be reviewed by a geotechnical engineer.

Based on previous experience, the use of piling shoes is considered to improve driveability of the piles and to

reduce the likelihood of damage to the piles when encountering obstructions or hard strata during piling. As such,

the use of piling shoes is considered acceptable for general usage. However, the selection of piling shoes is

strictly a constructability and cost decision as they do not provide any significant benefit to pile load capacity.

The actual pile capacity must be confirmed with acceptable refusal criteria during installation or as determined by

PDA testing.

5.2.4 Bored Cast-in-Place Piles

Bored CIP concrete piles founded in the deeper granular layers may be designed to resist axial compressive

loads on the basis of a combination of end-bearing and side friction. Piles may be designed to resist axial loads

on the basis of the ultimate bearing resistance and skin friction resistances provided in Table 5.2.4. The

geotechnical resistance factors recommended in Section 5.2.1 should be considered to calculate the ULS

factored values of shaft and base resistances. For piles constructed in accordance with the recommendations

made in this report, the following values of side friction and end-bearing may be used.

Table 5.2.4: Bored Cast-in-Place Pile Design Parameters

Depth(m)

Ultimate Shaft Resistance(kPa)

Ultimate Base Resistance*(kPa)

Above 3.0 m depth

(Sandy Clay/Clayey Sand Fill)0 N/A

>3.0 m (Granular Material) 30 1,500

Note that end bearing may only be considered in the event that CFA piles are used. Otherwise, the sand soils will

likely preclude effective pile base preparation and end bearing should not be considered. General

recommendations for the design and construction of bored CIP piles are included in Appendix C.

Based on the groundwater conditions and Tetra Tech EBA experience with excavation, groundwater seepage and

water infiltration is expected. The piling contractor should; however, make his own estimate of casing

requirements and should consider such factors as construction procedures and bore diameter. The piling

contractor selected should be experienced in the placement of concrete below water using tremie pipes because

there is some potential for significant groundwater inflows to be encountered during piling. Prior to construction of

any pile, the following equipment should be required on site; appropriate sizes and lengths of casing and cleaning

buckets as well as tremie pipes to allow placement of concrete beneath water. The use of a continuous flight

auger stem is recommended as the most suitable installation method, allowing consideration of end bearing as

well.



7


5.2.5 Lateral Pile Loading

The resistance of vertical piles to horizontal load involves soil-structure interaction and is commonly analyzed

using computer structural analysis or lateral pile analysis. The nature and level of sophistication of the various

analytical techniques varies, as do the required input parameters for the various software applications.

The commercially available software LPILE is one of the more advanced applications and is well recognized as a

valid application for lateral pile analysis. LPILE is used to analyze whether or not the laterally loaded piles exceed

the ultimate soil resistance, to predict pile head deflections and to predict the location of the maximum bending

moments and shear forces induced by lateral loads. If a higher level of confidence is required, a lateral pile load

test is recommended.

For structural analysts familiar with the difference between LPILE (or equivalent software) and the limitations of

other chosen alternate software, a range of commonly used parameters which may be used to predict deflections

for small strain elastic analyses are provided.

Typical input soil stiffness parameters used for simple static analyses include one or more of the following:

Modulus of Horizontal Subgrade Reaction (ks)

Coefficient of Horizontal Subgrade Reaction (k's)

Spring Constant (K)

These parameters are not fundamental soil properties and therefore, can vary widely depending upon how they

are derived and used by different practitioners. For small strain elastic analyses, the modulus of horizontal

subgrade reaction (ks) is related to the coefficient of horizontal subgrade reaction (k's) and pile diameter 'B' as

follows:

ks = k's / B (MPa/m)

Where:

k's = Coefficient of horizontal subgrade reaction (k's) for a 1 m diameter pile (MPa/m)

= 4 MPa for preliminary analysis of the clay and sand fill within the embankment at this site

and 10 MPa for the granular material

B = Pile diameter (m)

It is recommended that the design modulus of horizontal subgrade reaction (ks) value increase linearly from zero

at ground surface, to the value calculated from the above formula at a depth of 3 m. Below 3 m, the modulus of

horizontal subgrade reaction may be assumed to be the presented above for granular materials.

The spring constant (K) for use in modeling lateral pile capacity may be obtained as follows:

K = ksBL = k'sL (MN/m)

Where:

L = Length of pile segment (m)



8


The spring constant (K) is independent of pile diameter (B); however, the section modulus of the pile increases in

proportion to the pile diameter to the fourth power (B4). Therefore, with increasing pile diameter and section

modulus, the pile stiffness increases and the resulting lateral deflections decrease significantly.

If lateral loading is considered critical to the pile performance, care must be taken during pile installation to identify

voids developing adjacent to the piles. Due to the nature of the pile installation process (particularly for H-piles), it

is common to develop voids, which can significantly influence lateral loading on a pile. If voids develop, they

should be backfilled with granular fill, sand, fillcrete, or grout, depending on the size of the voids.

In the event the soil conditions do not provide adequate lateral foundation capacity for vertical piles, consideration

may be given to using battered piles to develop additional lateral resistance.

5.2.6 Excavation and Backfill

Excavations should be carried out in accordance with Alberta Occupational Health and Safety Regulations. The

consistencies of the soils encountered at the site should allow conventional hydraulic excavators to remove these

soils.

For temporary excavations within the cohesive soils deeper than 1.5 m (and up to 2.0 m deep), the sideslopes

should be shored and braced or the slopes cut 1.0 horizontal to 1.0 vertical (1.0H:1.0V) or flatter. Flatter

sideslopes may be required at depths below 2 m from grade. Where excavations are open for longer than one

month or if significant groundwater seepage is encountered, the sideslopes should be flatter than 1.0H:1.0V.

In areas below the groundwater table where sand and gravel is encountered, significantly shallower sideslopes

will be required.

If sloping of excavation sides is not feasible due to space limitations or other factors, then near vertical sided

excavations greater than 1.5 m deep should be shored or entered only in conjunction with an appropriate safety

device utilized in accordance with the manufacturer’s recommendations. Recommendations for shoring design

can be provided upon request.

Excavations left open for extended periods may collect groundwater seepage or surface runoff and channel water

infiltration. Any surface water or groundwater infiltration into an excavation should be diverted away from the

base and excavation slopes as it may result in soil softening and shallow slumping.

Temporary surcharge loads, such as construction materials and equipment, should not be allowed within 3.0 m of

an unsupported excavated face or the distance equal to the depth of excavation, whichever is greater. A further

set back may be required for deeper excavations. Vehicles delivering materials should be kept back from

excavated faces by at least 1 m.

Prior to allowing workers to enter, and particularly after periods of rain, construction excavations should be

carefully observed for evidence of instability, such as cracks, bulging, or soil loss from seepage areas. Small

earth falls from the sideslopes are a potential source of danger to workers and must be guarded against.

Evidence of excavation instability and/or seepage should be reported and corrected prior to allowing worker

access. Loose soil blocks and cobbles should be scaled from the excavation slopes prior to worker entry.

Excavations, roadway embankment, and bridge abutments must be backfilled in such a way as to minimize the

potential of differential settlement and frost heave movements. Roadway embankment and abutment should

generally be backfilled with soils similar to the adjacent native soils and the backfill should be compacted at

moisture contents within 2% of optimum moisture content (OMC) with a minimum compaction of 98% SPD.

For excavation backfill, a minimum compaction of 95% SPD is recommended, except for the top 600 mm, which

should be compacted to 98% SPD. The compacted thickness of each lift of backfill should not exceed 150 mm.



9


The upper 1.5 m of excavations should be cut at a maximum slope of 1.0H:1.0V, to avoid an abrupt transition

between backfill and in situ soil. The compacted thickness of each lift of backfill should not exceed 150 mm.

The site clay may be used as general engineered fill for backfilling, providing the fill used is free of organics or

other deleterious materials. The contractor should expect moisture conditioning may be required to achieve an

acceptable level of compaction.

Imported soil materials required must meet the requirements of general engineered fill provided in Appendix C.

The ultimate performance of the backfill is directly related to the uniformity of the backfill compaction. In order to

achieve this uniformity, the lift thickness and compaction criteria must be strictly enforced.

General recommendations regarding construction excavation, backfill materials, and compaction are contained in

Appendix C.

5.2.7 Seismic Factors

The site classification recommended for Seismic Site Response is Classification D, as noted in Table 4.1.8.4.a of

the National Building Code of Canada 2010.

5.2.8 Concrete Type

Testing was conducted to determine the water-soluble sulphate content of representative soil samples recovered

from site.

Based on the Canadian Standards Association (CSA) A23.1-09 Table 3, a severe (Exposure Class S-2)

classification should be adopted. Accordingly, based on CSA A23.1-09 Tables 2 and 3, the use of Type HS or

HSb (Sulphate Resistant) hydraulic cement at a maximum water/cementing material (w/cm) ratio of 0.45 is

recommended for foundation concrete and all concrete exposed to soil or groundwater.

CSA A23.1-09 Table 2 specifies air entrained concrete with a minimum 56-day compressive strength of 32 MPa

for a Class S-2 Exposure. The air content should be based on the appropriate air content category for the

corresponding nominal maximum aggregate size, as per CSA A23.1-09 Table 4. Increased compressive strength

and/or air content may be required due to structural requirements or other exposure considerations.

If concrete is placed in contact with imported fill, that fill should be tested for water-soluble sulphate content, and

the above recommendation re-evaluated.

6.0 DESIGN AND CONSTRUCTION GUIDELINES

General design and construction guidelines are provided in Appendix C, under the following supplemental

headings:

Backfill Materials and Compaction;

Construction Excavations;

Bored Cast-in-Place Piles; and

Driven Steel Piles.



10


These guidelines are intended to present standards of good practice. Although supplemental to the main text of

this report, they should be interpreted as part of the report. Design recommendations presented herein are based

on the premise that these guidelines will be followed. The design and construction guidelines are not intended to

represent detailed specifications for the works although they may prove useful in the preparation of such

specifications. In the event of any discrepancy between the main text of this report and Appendix C, the main text

should govern.




FIGURES

Figure 1 Borehole Location Plan

BH-ABH-B

LSD 1-13-031-27 W4MLSD 2-13-031-27 W4M

LSD 16-12-031-27 W4MLSD 15-12-031-27 W4M

TWP RD 312

HWY

582

C:\Users\leanne.hughes\Documents\L12103641\L12103641-01_FIG1_R0.dwg [FIGURE] September 03, 2014 - 1:11:47 pm (BY: HUGHES, LEANNE)

CLIENT

PROJECT NO. DWN CKD REV

OFFICE DATE

Figure

EBA

September 2014EBA-Lethbridge

0KHLCHL12103641-01

Roseke Engineering Ltd.

Bridge Replacement

Twp Rd 312 in LSD 2-13-031-27 W4M

BOREHOLE LOCATION PLAN

Image © 2014 Digital Globe

LEGEND:

- BOREHOLE LOCATION

0 150 m

Scale: 1:3000 @ 8.5"x11"




APPENDIX ATETRA TECH’S GENERAL CONDITIONS

GENERAL CONDITIONS

1

GEOTECHNICAL REPORT

This report incorporates and is subject to these “General Conditions”.

1.0 USE OF REPORT AND OWNERSHIP

This geotechnical report pertains to a specific site, a specific

development and a specific scope of work. It is not applicable to anyother sites nor should it be relied upon for types of development

other than that to which it refers. Any variation from the site or

development would necessitate a supplementary geotechnicalassessment.

This report and the recommendations contained in it are intended

for the sole use of Tetra Tech EBA’s Client. Tetra Tech EBA doesnot accept any responsibility for the accuracy of any of the data, the

analyses or the recommendations contained or referenced in the

report when the report is used or relied upon by any party otherthan Tetra Tech EBA’s Client unless otherwise authorized in writing

by Tetra Tech EBA. Any unauthorized use of the report is at the

sole risk of the user.

This report is subject to copyright and shall not be reproduced either

wholly or in part without the prior, written permission of Tetra TechEBA. Additional copies of the report, if required, may be obtained

upon request.

2.0 ALTERNATE REPORT FORMAT

Where Tetra Tech EBA submits both electronic file and hard copy

versions of reports, drawings and other project-related documentsand deliverables (collectively termed Tetra Tech EBA’s instruments

of professional service), only the signed and/or sealed versions

shall be considered final and legally binding. The original signedand/or sealed version archived by Tetra Tech EBA shall be deemed

to be the original for the Project.

Both electronic file and hard copy versions of Tetra Tech EBA’sinstruments of professional service shall not, under any

circumstances, no matter who owns or uses them, be altered by

any party except Tetra Tech EBA. Tetra Tech EBA’s instruments ofprofessional service will be used only and exactly as submitted by

Tetra Tech EBA.

Electronic files submitted by Tetra Tech EBA have been prepared

and submitted using specific software and hardware systems. Tetra

Tech EBA makes no representation about the compatibility of thesefiles with the Client’s current or future software and hardware

systems.

3.0 ENVIRONMENTAL AND REGULATORY ISSUES

Unless stipulated in the report, Tetra Tech EBA has not been

retained to investigate, address or consider and has notinvestigated, addressed or considered any environmental or

regulatory issues associated with development on the subject site.

4.0 NATURE AND EXACTNESS OF SOIL AND

ROCK DESCRIPTIONS

Classification and identification of soils and rocks are based upon

commonly accepted systems and methods employed in

professional geotechnical practice. This report contains descriptionsof the systems and methods used. Where deviations from the

system or method prevail, they are specifically mentioned.

Classification and identification of geological units are judgmental innature as to both type and condition. Tetra Tech EBA does not

warrant conditions represented herein as exact, but infers accuracy

only to the extent that is common in practice.

Where subsurface conditions encountered during development are

different from those described in this report, qualified geotechnicalpersonnel should revisit the site and review recommendations in

light of the actual conditions encountered.

5.0 LOGS OF TESTHOLES

The testhole logs are a compilation of conditions and classification

of soils and rocks as obtained from field observations andlaboratory testing of selected samples. Soil and rock zones have

been interpreted. Change from one geological zone to the other,

indicated on the logs as a distinct line, can be, in fact, transitional.The extent of transition is interpretive. Any circumstance which

requires precise definition of soil or rock zone transition elevations

may require further investigation and review.

6.0 STRATIGRAPHIC AND GEOLOGICAL INFORMATION

The stratigraphic and geological information indicated on drawingscontained in this report are inferred from logs of test holes and/or

soil/rock exposures. Stratigraphy is known only at the locations of

the test hole or exposure. Actual geology and stratigraphy betweentest holes and/or exposures may vary from that shown on these

drawings. Natural variations in geological conditions are inherent

and are a function of the historic environment. Tetra Tech EBA doesnot represent the conditions illustrated as exact but recognizes that

variations will exist. Where knowledge of more precise locations of

geological units is necessary, additional investigation and reviewmay be necessary.

GENERAL CONDITIONS

GEOTECHNICAL REPORT

2

7.0 PROTECTION OF EXPOSED GROUND

Excavation and construction operations expose geological materialsto climatic elements (freeze/thaw, wet/dry) and/or mechanical

disturbance which can cause severe deterioration. Unless otherwise

specifically indicated in this report, the walls and floors ofexcavations must be protected from the elements, particularly

moisture, desiccation, frost action and construction traffic.

8.0 SUPPORT OF ADJACENT GROUND AND STRUCTURES

Unless otherwise specifically advised, support of ground and

structures adjacent to the anticipated construction and preservationof adjacent ground and structures from the adverse impact of

construction activity is required.

9.0 INFLUENCE OF CONSTRUCTION ACTIVITY

There is a direct correlation between construction activity and

structural performance of adjacent buildings and other installations.The influence of all anticipated construction activities should be

considered by the contractor, owner, architect and prime engineer

in consultation with a geotechnical engineer when the final designand construction techniques are known.

10.0 OBSERVATIONS DURING CONSTRUCTION

Because of the nature of geological deposits, the judgmental nature

of geotechnical engineering, as well as the potential of adverse

circumstances arising from construction activity, observationsduring site preparation, excavation and construction should be

carried out by a geotechnical engineer. These observations may

then serve as the basis for confirmation and/or alteration ofgeotechnical recommendations or design guidelines presented

herein.

11.0 DRAINAGE SYSTEMS

Where temporary or permanent drainage systems are installedwithin or around a structure, the systems which will be installed

must protect the structure from loss of ground due to internal

erosion and must be designed so as to assure continuedperformance of the drains. Specific design detail of such systems

should be developed or reviewed by the geotechnical engineer.

Unless otherwise specified, it is a condition of this report thateffective temporary and permanent drainage systems are required

and that they must be considered in relation to project purpose and

function.

12.0 BEARING CAPACITY

Design bearing capacities, loads and allowable stresses quoted inthis report relate to a specific soil or rock type and condition.

Construction activity and environmental circumstances can

materially change the condition of soil or rock. The elevation atwhich a soil or rock type occurs is variable. It is a requirement of

this report that structural elements be founded in and/or upon

geological materials of the type and in the condition assumed.Sufficient observations should be made by qualified geotechnical

personnel during construction to assure that the soil and/or rock

conditions assumed in this report in fact exist at the site.

13.0 SAMPLES

Tetra Tech EBA will retain all soil and rock samples for 30 daysafter this report is issued. Further storage or transfer of samples can

be made at the Client’s expense upon written request, otherwise

samples will be discarded.

14.0 INFORMATION PROVIDED TO TETRA TECH EBA BY

OTHERS

During the performance of the work and the preparation of the

report, Tetra Tech EBA may rely on information provided bypersons other than the Client. While Tetra Tech EBA endeavours to

verify the accuracy of such information when instructed to do so by

the Client, Tetra Tech EBA accepts no responsibility for theaccuracy or the reliability of such information which may affect the

report.




APPENDIX BSOIL DESCRIPTION GUIDELINE AND BOREHOLE LOGS

Tt_Borehole Terms_General.cdr

TERMS USED ON BOREHOLE LOGS

COARSE GRAINED SOILS (major portion retained on 0.075mm sieve): Includes (1) clean gravels and sands, and (2) silty or clayey gravels and sands. Condition is rated according to relative density, as inferred from laboratory or in situ tests.

FINE GRAINED SOILS (major portion passing 0.075mm sieve): Includes (1) inorganic and organic silts and clays, (2) gravelly, sandy, or silty clays, and (3) clayey silts. Consistency is rated according to shearing strength, as estimated from laboratory or in situ tests.

DESCRIPTIVE TERM

Very LooseLoose

CompactDense

Very Dense

RELATIVE DENSITY

0 TO 20%20 TO 40%40 TO 75%75 TO 90%90 TO 100%

N (blows per 0.3m)

0 to 44 to 1010 to 3030 to 50

greater than 50

The number of blows, N, on a 51mm O.D. split spoon sampler of a 63.5kg weight falling 0.76m, required to drive the sampler a distance of 0.3m from 0.15m to 0.45m.

NOTE: Slickensided and fissured clays may have lower unconfined compressive strengths than shown above, because of planes of weakness or cracks in the soil.

DESCRIPTIVE TERM

Very SoftSoftFirmStiff

Very StiffHard

UNCONFINED COMPRESSIVE STRENGTH (KPA)

Less than 2525 to 5050 to 100100 to 200200 to 400

Greater than 400

TERMS DESCRIBING CONSISTENCY OR CONDITION

Slickensided - having inclined planes of weakness that are slick and glossy in appearance.Fissured - containing shrinkage cracks, frequently filled with fine sand or silt; usually more or less vertical.Laminated - composed of thin layers of varying colour and texture.Interbedded - composed of alternate layers of different soil types.Calcareous - containing appreciable quantities of calcium carbonate.;Well graded - having wide range in grain sizes and substantial amounts of intermediate particle sizes.Poorly graded - predominantly of one grain size, or having a range of sizes with some intermediate size missing.

GENERAL DESCRIPTIVE TERMS

Data presented hereon is for the sole use of the stipulated client. Tetra Tech EBA is not responsible, nor can be held liable, for use made of this report by any other party, with or without the knowledge of EBA. The testing services reported herein have been performed to recognized industry standards, unless noted. No other warranty is made. These data do not include or represent any interpretation or opinion of specification compliance or material suitability. Should engineering interpretation be required, EBA will provide it upon written request.

SAND (FILL) - silty, trace clay, trace gravel, well graded,fine grained, damp to moist, dense, brown

CLAY (TILL) - silty, some sand, trace gravel, moist, verystiff, medium plastic, dark grey, coal and oxidespecks

SAND -silty, trace to some clay, some gravel, fine grained,well graded, moist, compact, dark grey

... wet

... dense

CLAY (TILL)- silty, sandy, trace gravel, moist to very moist,hard, low plastic, dark grey, coal and oxide specks,sand lenses and pockets

End of Borehole @ 15.0 mSeepage from 4.0 m, Sloughing to 9.4 m on CompletionSlotted PVC Standpipe Installed to 9.4 mIndicated Water Level Measured August 8, 2014

B1

D1

B2

D2

B3

D3

B4

D4

B5D5D6

D7

D8B6D9

D10

D11B7

B8

D12

D13B9

D10

D11

B10

15

16

10

23

22 56

89

100

100

100

100

37

81

100

100

8/8/

14

8/8/

14

5.8

18.5

13.4

13

14.8

14.3

17.8

16.4

20.3

17.9

CORESHELBY TUBEA-CASINGSPTNO RECOVERYDISTURBED

SOILDESCRIPTION

SAM

PLE

TYPE

SAM

PLE

NU

MBE

R

SPT

(N)

SLOUGH DRILL CUTTINGSGROUTPEA GRAVELBENTONITE

LOGGED BY: KHREVIEWED BY: KHDRAWING NO:

PROJECT: BRIDGE REPLACEMENT

LOCATION: TWP RD 312 in LSD 2-13-031-27 W4

SITE LOCAL: NEAR DIDSBURY, AB

16.5

SAMPLE TYPE

BACKFILL TYPE

GEOTECHNICAL L12103641.GPJ EBA.GDT 9/24/14

SAND

Elev

atio

n (m

)

0

COMPLETION DEPTH: 15 mCOMPLETE: 7/23/2014Page 1 of 1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

915.0

914.0

913.0

912.0

911.0

910.0

909.0

908.0

907.0

906.0

905.0

904.0

903.0

902.0

901.0

900.0

899.0

CLIENT: ROSEKE ENGINEERING LTD.

SOLID STEM AUGER

5725482N; 313416E; Zone 12

PROJECT NO. - BOREHOLE NO.

L12103641-01 BH A (WEST)

ELEVATION: 915 m

Dep

th (m

)

80

100 POCKET PEN. (kPa)

UNC. COMPRESSIVE STRENGTH (kPa) 50

20

MO

ISTU

RE

CO

NTE

NT

LIQUID 150 200

400

60

3004020

M.C.PLASTIC

2001008060

40 STANDARD PENETRATION (N)

WES

T

SAND (FILL) - silty, trace clay, trace gravel, well graded,fine grained, damp to moist, dense, brown

CLAY (TILL) - silty, sandy, trace gravel, damp to moist,hard, low plastic, dark grey, coal and oxide specks

... very stiff

... soluble sulphate content = 0.075 @ 5.25 m

SAND - silty, trace clay, trace gravel, poorly graded, finegrained, wet, compact, dark grey

CLAY (TILL) - silty, sandy, damp to moist, very stiff, lowplastic, dark grey, coal and oxide specks, sand lensesand pockets

... very moist

End of Borehole @ 15.0 mSeepage from 6.0 m, Sloughing to 12.2 m on CompletionSlotted PVC Standpipe Installed to 12.2 mIndicated Water Level Measured August 8, 2014

B1

D1

B2

D2

B3

D3

B4

D4

B5

D5

B6

D6

D7B7D8

D9

D10B8

D11

D12

D13

D14

D15

D16B9

32

51

28

11

21

26

37

55

40

40

79

75

45

51

89

84

82

8/8/

14

8/8/

14

5.4

3.9

12.2

10.9

15.4

13.1

18.8

17.6

21.7

CORESHELBY TUBEA-CASINGSPTNO RECOVERYDISTURBED

SOILDESCRIPTION

SAM

PLE

TYPE

SAM

PLE

NU

MBE

R

SPT

(N)

SLOUGH DRILL CUTTINGSGROUTPEA GRAVELBENTONITE

LOGGED BY: KHREVIEWED BY: KHDRAWING NO:

PROJECT: BRIDGE REPLACEMENT

LOCATION: TWP RD 312 in LSD 2-13-031-27 W4

SITE LOCAL: NEAR DIDSBURY, AB

16.5

SAMPLE TYPE

BACKFILL TYPE

GEOTECHNICAL L12103641.GPJ EBA.GDT 9/24/14

SAND

Elev

atio

n (m

)

0

COMPLETION DEPTH: 15 mCOMPLETE: 7/23/2014Page 1 of 1

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

919.0

918.0

917.0

916.0

915.0

914.0

913.0

912.0

911.0

910.0

909.0

908.0

907.0

906.0

905.0

904.0

903.0

CLIENT: ROSEKE ENGINEERING LTD.

SOLID STEM AUGER

5725481N; 313496E; Zone 12

PROJECT NO. - BOREHOLE NO.

L12103641-01 BH B (EAST)

ELEVATION: 919 m

Dep

th (m

)

80

100 POCKET PEN. (kPa)

UNC. COMPRESSIVE STRENGTH (kPa) 50

20

MO

ISTU

RE

CO

NTE

NT

LIQUID 150 200

400

60

3004020

M.C.PLASTIC

2001008060

40 STANDARD PENETRATION (N)

EAST




APPENDIX CCONSTRUCTION GUIDELINES

CONSTRUCTION GUIDELINE

1

BACKFILL MATERIALS AND COMPACTION (ALBERTA)

1.0 DEFINITIONS

“Landscape fill” is typically used in areas such as berms and grassed areas where settlement of the fill and

noticeable surface subsidence can be tolerated. “Landscape fill” may comprise soils without regard to engineering

quality.

“General engineered fill” is typically used in areas where a moderate potential for subgrade movement is

tolerable, such as asphalt (i.e., flexible) pavement areas. “General engineered fill” should comprise clean,

inorganic granular or clay soils.

“Select engineered fill” is typically used below slabs-on-grade or where high volumetric stability is desired, such

as within the footprint of a building. “Select engineered fill” should comprise clean, well-graded granular soils or

inorganic low to medium plastic clay soils.

“Structural engineered fill” is used for supporting structural loads in conjunction with shallow foundations.

“Structural engineered fill” should comprise clean, well-graded inorganic granular soils.

“Lean-mix concrete” is typically used to protect a subgrade from weather effects including excessive drying or

wetting. “Lean-mix concrete” can also be used to provide a stable working platform over weak subgrades.

“Lean-mix concrete” should be low strength concrete having a minimum 28-day compressive strength of 3.5 MPa.

Standard Proctor Density (SPD) as used herein means Standard Proctor Maximum Dry Density (ASTM Test

Method D698). Optimum moisture content is defined in ASTM Test Method D698.

2.0 GENERAL BACKFILL AND COMPACTION RECOMMENDATIONS

Backfill adjacent to and above footings, abutment walls, basement walls, grade beams and pile caps or below

highway, street or parking lot pavement sections should comprise “general engineered fill” materials as defined

above.

Exterior backfill adjacent to footings, foundation walls, grade beams and pile caps and within 600 mm of final

grade should comprise inorganic, cohesive “general engineered fill”. Such backfill should provide a relatively

impervious surface layer to reduce seepage into the subsoil.

Backfill should not be placed against a foundation structure until the structure has sufficient strength to withstand

the earth pressures resulting from placement and compaction. During compaction, careful observation of the

foundation wall for deflection should be carried out continuously. Where deflections are apparent, the compactive

effort should be reduced accordingly.

In order to reduce potential compaction induced stresses, only hand held compaction equipment should be used

in the compaction of fill within 1 m of retaining walls or basement walls.

All lumps of materials should be broken down during placement. Backfill materials should not be placed in a

frozen state, or placed on a frozen subgrade.



2

Where the maximum-sized particles in any backfill material exceed 50 percent of the minimum dimension of the

cross-section to be backfilled (e.g., lift thickness), such particles should be removed and placed at other more

suitable locations on-site or screened off prior to delivery to site.

Bonding should be provided between backfill lifts, if the previous lift has become desiccated. For fine-grained

materials the previous lift should be scarified to the base of the desiccated layer, moisture-conditioned and

recompacted and bonded thoroughly to the succeeding lift. For granular materials, the surface of the previous lift

should be scarified to about a 75 mm depth followed by proper moisture-conditioning and recompaction.

3.0 COMPACTION AND MOISTURE CONDITIONING

“Landscape fill” material should be placed in compacted lifts not exceeding 300 mm and compacted to a density

of not less than 90 percent of SPD.

“General engineered fill” and “select engineered fill” materials should be placed in layers of 150 mm compacted

thickness and should be compacted to not less than 98 percent of SPD. Note that higher compaction levels may

be specified within 300 mm of the design elevation. Cohesive materials placed as “general engineered fill” or

“select engineered fill” should be compacted at 0 to 2 percent above the optimum moisture content. Granular

materials placed as “general engineered fill” or “select engineered fill” should be compacted at slightly below the

optimum moisture content.

“Structural engineered fill” material should be placed in compacted lifts not exceeding 150 mm in thickness and

compacted to not less than 100 percent of SPD at slightly below the optimum moisture content.

4.0 “GENERAL ENGINEERED FILL” SPECIFICATIONS

Low to high plastic clay is considered acceptable for use as “general engineered fill,” assuming this material is

inorganic and free of deleterious materials.

Materials meeting the specifications for “select engineered fill” or “structural engineered fill” as described below

would also be acceptable for use as “general engineered fill.”

5.0 “SELECT ENGINEERED FILL” SPECIFICATIONS

Low to medium plastic clay with the following range of plasticity properties is generally considered suitable for use

as “select engineered fill”:

Liquid Limit = 20 to 40%

Plastic Limit = 10 to 20%

Plasticity Index = 10 to 30%



3

“Pit-run gravel” and “fill sand” that meet the following specifications are generally considered acceptable for use

as “select engineered fill.”

Granular “Select Engineered Fill” – Percent Passing by Weight

Sieve SizePit-run Gravel

(AT D6-C80)Fill Sand

80 mm 100 --

50 mm 55 – 100 --

25 mm 38 – 100 100

16 mm 32 – 85 --

5.0 mm 20 – 65 75 – 100

630 m -- 45 – 80

315 m 6 – 30 --

80 m 2 – 10 2 – 10

The “pit-run gravel” should be free of any form of coating and any gravel or sand containing clay, loam or other

deleterious materials should be rejected. No oversize material should be tolerated.

The materials above are also suitable for use as “general engineered fill.”

6.0 “STRUCTURAL ENGINEERED FILL” SPECIFICATIONS

Crushed gravel used as “structural engineered fill” should be hard, clean, well graded, crushed aggregate, free of

organics, coal, clay lumps, coatings of clay, silt and other deleterious materials. The aggregates should conform

to the following gradation requirement when tested in accordance with ASTM C136:

“Structural Engineered Fill” – Percent Passing by Weight

Sieve Size20 mm Crush

(AT D2-C20)

40 mm Crush

(AT D2-C40)

40 mm 100

25 mm 70 – 94

20 mm 100 --

16 mm 84 – 94 55 – 85

10 mm 63 – 86 44 – 74

5.0 mm 40 – 67 32 – 62

1.25 mm 20 – 43 17 – 43

630 m 14 – 34 12 – 34

315 m 9 – 26 8 – 26

160 m 5 – 18 5 – 18

80 m 2 – 10 2 – 10



4

In addition to the above grading limits, the following criteria should be met:

“Structural Engineered Fill” – Additional Material Properties

Material TypePercentage of Material Retained on

5 mm Sieve having Two or MoreFractured Faces

Plasticity Index

(<400 m)

L.A. Abrasion Loss

(percent Mass)

20 mm Crush 60 min 6 max 50 max

40 mm Crush 50 min 6 max 50 max

Materials that meet the above grading limits and material property criteria are also suitable for use as “select

engineered fill.”

7.0 DRAINAGE MATERIALS

“Coarse gravel” for drainage or weeping tile bedding should conform to the following grading:

“Coarse Gravel” Drainage Material – Percent Passing by Weight

Sieve Size25 mm Gravel

(AT D8-C25)20 mm Gravel

40 mm -- --

28 mm -- 100

25 mm 100 --

20 mm -- 85 – 100

16 mm 90 – 100 --

14 mm -- 60 – 90

10 mm 45 – 75 --

5 mm 0 – 15 0 – 10

2.5 mm -- 0 – 5

1.25 mm 0 – 5 --

“Coarse sand” for drainage should conform to the following grading limits:

“Coarse Sand” Drainage Material – Percent Passing by Weight

Sieve Size Coarse Sand*

10 mm 100

5 mm 95 – 100

2.5 mm 80 – 100

1.25 mm 50 – 90

630 m 25 – 65

315 m 10 – 35

160 m 2 – 10

80 m 0 – 3

* From CSA A23.1-09, Table 10, “Grading Limits for Fine Aggregate”, Class FA1

Note that the “coarse sand” above is also suitable for use as pipe bedding material.



5

8.0 BEDDING MATERIALS

The “fill sand” gradation presented above in Section 5.0 is suitable for use as pipe bedding and as backfill within

the pipe embedment zone. If drainage is also a consideration, “coarse sand” presented in Section 7.0 above

should be used.


1

CONSTRUCTION EXCAVATIONS

Construction should be in accordance with good practice and comply with the requirements of the responsible

regulatory agencies.

All excavations greater than 1.5 m deep should be sloped or shored for worker protection.

Shallow excavations up to about 3 m depth may use temporary sideslopes of 1H:1V. A flatter slope of 2H:1V

should be used if groundwater is encountered. Localized sloughing can be expected from these slopes.

Deep excavations or trenches may require temporary support if space limitations or economic considerations

preclude the use of sloped excavations.

For excavations greater than 3 m depth, temporary support should be designed by a qualified geotechnical

engineer. The design and proposed installation and construction procedures should be submitted to Tetra Tech

EBA for review.

The construction of a temporary support system should be monitored. Detailed records should be taken of

installation methods, materials, in situ conditions and the movement of the system. If anchors are used, they

should be load tested. Tetra Tech EBA can provide further information on monitoring and testing procedures if

required.

Attention should be paid to structures or buried service lines close to the excavation. For structures, a general

guideline is that if a line projected down, at 45 degrees from the horizontal from the base of foundations of

adjacent structures intersects the extent of the proposed excavation, these structures may require underpinning

or special shoring techniques to avoid damaging earth movements. The need for any underpinning or special

shoring techniques and the scope of monitoring required can be determined when details of the service ducts and

vaults, foundation configuration of existing buildings and final design excavation levels are known.

No surface surcharges should be placed closer to the edge of the excavation than a distance equal to the depth

of the excavation, unless the excavation support system has been designed to accommodate such surcharge.


1

BORED CAST-IN-PLACE CONCRETE PILES

Design and construction of piles should comply with relevant Building Code requirements.

Piles should be installed under full time inspection of geotechnical personnel. Pile design parameters should be

reviewed in light of the findings of the initial bored shafts drilled on a site. Further design review may be necessary

if conditions observed during site construction do not conform to design assumptions.

Where fill material or lenses or strata of sand, silt or gravel are present within the designed pile depth, these may

be incompetent and/or water bearing and may cause sloughing. Casing should be on hand before drilling starts

and be used, if necessary, to seal off water and/or prevent sloughing of the hole.

If piles are to be underreamed (belled), the underreams should be formed entirely in self-supporting soil and

entirely within the competent bearing stratum. Where caving occurs at design elevation it may be necessary to

extend the base of the pile bell to a greater depth. Piles may be constructed with bells having outside diameters

up to approximately three times the diameters of their shafts. Piles with shaft diameters of less than 400 mm

should not be underreamed due to difficulties associated with ensuring a clean base.

Prior to pouring concrete, bottoms of pile bells or of straight shaft end bearing piles should be cleaned of all

disturbed material.

Pile excavations should be visually inspected after completion to ensure that disturbed materials and/or water are

not present on the base so that recommended allowable bearing and skin friction parameters may apply.

Visual inspection may be accomplished by the inspector descending into the pile shaft (shaft diameter of 760 mm

(30 inch) or greater). A protective cage and other safety equipment required by government regulations should be

provided by the contractor to facilitate downhole inspection.

Other procedures to inspect the pile shafts may be used where shaft diameters of less than 760 mm (30 inch) are

constructed, such as, inspection with a light.

For safety reasons, where hand cleaning and/or 'down shaft' inspection by personnel are required, the pile shaft

must be cased full length prior to personnel entering the shaft.

Reinforcing steel should be on hand and should be placed as soon as the bore has been completed and

approved.

Longitudinal reinforcing steel is recommended to counteract the possible tensile stresses induced by frost action

and should extend to a minimum depth of 3.5 m. A minimum steel of 0.5 percent of the gross shaft area is

recommended.

Where a limited quantity of water is present on the pile base, when permitted or directed by a geotechnical

engineer, it should be either removed or absorbed by the addition of dry cement, which should then be thoroughly

mixed as an in situ slurry by means of the belling tool, using reverse rotation of the tool. Where significant

quantities of water are present and it is impracticable to exclude water from the pile bore, concrete should be

placed by tremie techniques or concrete pump.

A "dry" pile should be poured by "free fall" of concrete only where impact of the concrete against the reinforcing

cage, which can cause segregation of the concrete, will not occur. A hopper should be used to direct concrete

down the centre of the pile base and to prevent impact of concrete against reinforcing steel.



2

Concrete used for "dry" uncased piles should be self-compacting and should have a target slump of 125 mm.

Where casing is required to prevent sloughing or seepage, the slump should be increased to 150 mm. In order to

comply with maximum water:cement ratios for the concrete, the use of chemicals (or superplasticizers) to

temporarily increase the slump may be required. Concrete for each pile should be poured in one continuous

operation and should be placed immediately after excavation and inspection of piles, to reduce the opportunity for

the ingress of free water or deterioration of the exposed soil or rock.

If piles cannot be formed in dry conditions then the concrete should be placed by tremie tube or concrete pump.

Concrete placed by tremie should have a slump of not less than 150 mm. A ball or float should be used in the

tremie tube to separate the initial charge of concrete from the water in the pile hole. The outlet of the tremie tube

should be maintained at all times 1.0 m to 2.0 m below the surface of the concrete. The diameter of the tremie

tube should be at least 200 mm. The tube should be water tight and not be made of aluminum. Smaller diameter

pipes may be used with a concrete pump. The surface of the concrete should be allowed to rise above the cut off

level of the pile, so that when the temporary casing is withdrawn and the surface level of the concrete adjusts to

the new volume, the top of the uncontaminated concrete is at or above the cut off level. The concrete should be

placed in one continuous smooth operation without any halts or delays. Placing the lower portion of the pile by

tremie tube and placing the upper portion of the pile by "free fall" should not be permitted, to ensure that defects

in the pile shaft at the top of the tremie concrete do not occur. As the surface of the concrete rises in the pile bore

the water in the pile bore will be displaced upwards and out of the top of the pile casing. It may be necessary to

pump off this water to a container or temporary ditch drain to prevent the formation of ice or flooding conditions,

and possibly damage to existing structures.

When concreting piles by tremie techniques, allowance should be made for the removal of contaminated or

otherwise defective concrete at the tops of the piles.

The casing should be filled with concrete and then the casing should be withdrawn smoothly and continuously.

Sufficient concrete should be placed to allow for the additional volume of the casing and reduction in level of the

concrete as the casing is withdrawn. Concrete should not be poured on top of previously poured concrete, after

the casing is withdrawn.

An accurate record of the volume of concrete placed should be maintained as a check that a continuous pile had

been formed.

Concrete should not be placed if its temperature is less than 5C or exceeds 30C, or if it is more than two hours

old.

Where tension, horizontal or bending moment loading on the pile is foreseen, steel reinforcing should be

extended and tied into the grade beam or pile cap. The steel should be designed to transfer loads to the required

depth in the pile and to resist resultant bending moments and shear forces.

Void formers should be placed beneath all grade beams to reduce the risk of damage due to frost effects or soil

moisture changes.

Where the drilling operation might affect the concrete in an adjacent pile (i.e., where pile spacing is less than

about three diameters) drilling should not be carried out before the previously poured pile concrete has set for at

least 24 hours.

Where a group of four or more piles are used the allowable working load on the piles may need to be modified to

allow for group effects.



3

Piles should be spaced no closer than 2.5 times the pile shaft diameter, measured centre-to-centre. Strict control

of pile location and verticality should be exercised to provide accurate locations and spacings of piles. In general,

piles should be constructed within a tolerance of 75 mm plan distance in any direction and within a verticality of

1 in 75.

A detailed record should be kept of pile construction; the following information should be included, pile number,

shaft/base diameter, date and time bored, date and time concreted, elevation of piling platform, depths (from

piling platform level) to pile base and to concrete cut off level, length of casing used, details of reinforcement,

details of any obstructions, details of any groundwater inflows, brief description of soils encountered in the bore

and details of any unusual occurrences during construction.

If a large number of piles are to be installed, it may be possible to optimize the design on the basis of pile load

tests.


1

DRIVEN STEEL PILES

Full time observation of pile driving should be carried out by competent geotechnical personnel.

Piles should initially be designed for minimum section and embedment on the basis of static design loads, shaft

resistance and tip resistance.

Final design of driven steel piles could be carried out using a wave equation analysis. Design by this method will

enable an optimum match of hammer type and weight to pile type and soil conditions and allow a check to be

made on driving stresses. Pile design should be reviewed in the light of actual driving records.

Steel piles should conform to the requirements of the applicable building code. When steel pipe piles are filled

with concrete, it should conform to the requirements of the applicable building code but should be of sufficient

slump (150 mm or greater) to prevent voids forming, and its consistency should be such as to prevent

segregation.

Driving records should be kept for each pile. Information to be recorded should include, pile dimensions, hammer

type, rated energy, ram weight, cap block weight and type, anvil weight, number of blows for each 0.3 m of

penetration and final set.

The elevation of the tops of driven piles should be measured immediately after driving. If uplift occurs in any piles

during the driving of adjacent piles, the displaced piles should be re-driven to at least their previous final elevation

and final set.

Piles should be spaced no closer than 2.5 times the pile diameter, measured centre-to-centre. Where piles are

driven in groups, they should be driven from the centre outwards. In general, all piles in a group should be driven

to approximately the same tip elevation. If a group of four or more piles is required, group effects may reduce the

working load of the pile group below that calculated from the number of piles multiplied by the working load for an

individual pile. If required, Tetra Tech EBA can provide further design parameters for this case at the final design

stage.

Strict control of pile location and orientation should be exercised to obtain accurate pile installation. Pre-boring of

the surficial soils may be necessary to ensure proper location of the pile tip.

When piles are to be driven into very hard or frozen strata or boulders, special tips or preboring may be required.

For piles which will displace a significant amount of soil during driving, such as closed-end pipe piles, care should

be taken that the driving will not cause strains of such magnitude as to cause damage to nearby structures.

Pile driving may result in significant vibrations which may be unacceptable for adjacent structures. In areas where

this is a concern, continuous monitoring of vibrations induced in adjacent structures by a seismograph is

recommended in order to assess the potential for damage and the need for modification of procedures.

If a large number of piles are to be installed, it may be possible to optimize the design on the basis of pile load

tests.




APPENDIX DLABORATORY RESULTS




APPENDIX ESELECTION OF SITE PHOTOS



1

Geotechnical Evaluation - Bridge Replacement - Photos.docx

Photo 1: Existing bridge, photo taken from the north side of the bridge on the west banklooking south

Photo 2: Existing bridge, photo taken from the north side of the bridge on the east banklooking southwest



2

Geotechnical Evaluation - Bridge Replacement - Photos.docx

Photo 3: Drilling at borehole location BH A (west),

photo taken west of drilling location lookingeast

Photo 4: Drilling at borehole location BH B (east), photo

taken west of drilling location looking eastPhoto 4: