The Refurbishment of the Impala Athene Hillside 1&2 – 132 Kv Bypass Lines.

Tender Summary:

PSCED0332

See details below or the tender documentation

Tender Closed on: 2020-09-08 10:00

Electrical Cable Supplies, Installation and Maintenance, Electrical Engineering, Electrical Equipment and Supplies, Electrical Services, Manufacture of computer, electronic and optical products

KwaZulu-Natal

ESKOM

ESKOM Tenders

Bid Number: PSCED0332
Bid Description:The refurbishment of the Impala Athene Hillside 1&2 132kV bypass lines
Name of Institution:Eskom Holdings SOC Limited
Place where goods, works or services are required: Kwa-Zulu Natal
 


Date Published:  03 August 2020
Closing Date / Time: 08 September 2020
Enquiries:
Contact Person:Julitha Boloko
Email:[email protected]
Telephone number:011 800 2772
FAX Number:086 605 2281


Where bid documents can be obtained:
Website:www.eskom.co.za
Physical Address: No1 Maxwell Drive, Sunnighill, Johannesburg

Where bids should be delivered:
Physical Address: The Tender Office, Megawatt Park Retail Centre,


Northside, No 1 Maxwell Drive,Sunninghill


Briefing Session
A compulsory / Optional briefing session will be held on:
Date:
Time:
Venue:


Special Conditions:


 



{TENDER_DOCUMENTS_TEXT_START} -------------------
03 August 2020
.Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
1 of 104
Technical Instruction
Title: THE STANDARD FOR THE
CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC
5.2)
Unique Identifier:
Technology
240-47172520
Alternative Reference TRMSCAAC 5.2
Number:
Part:
Part 0 – General
Revision:
5.2
Total Pages:
100
Date:
30 January 2015
Disclosure
Classification:
Controlled Disclosure
Compiled by
Supported by
Authorized by
Dan Dukhan and Willem
Combrinck
Riaz Vajeth
Prince Moyo
SCOT Lines Study
Committee Chairperson
General Manager
Power Delivery Engineering
Date:
Date:
Chief Engineers
Line Engineering
Date:
ESKOM COPYRIGHT PROTECTED
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Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
2 of 104
Technical Instructions
Title: THE STANDARD FOR THE

Unique Identifier:
CONSTRUCTION OF
OVERHEAD POWERLINES
(TRMSCAAC5)

Disclosure Classification:
Group Technology

240-47172520

(TRMSCAAC5.2)

Area of Applicability:

Eskom Wide

Documentation Type:

Technical
Instructions

Revision:

5.2

Total Pages:

98

Next Review Date:

March 2016

Controlled Disclosure
Compiled by
Approved by
…………………………………………………
……………………………………………..…….
Dan Dukhan & Willem Combrinck
Riaz Vajeth
Line Engineering Services
SCOT LINES Study Committee Chairperson
Date: ……………………………………………
Date: ………………………………………………
ESKOM COPYRIGHT PROTECTED
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Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
3 of 104
Content
Page
Instruction ........................................................................................................................................................... 7
Applicability ......................................................................................................................................................... 7
Revision history .................................................................................................................................................. 7
Development team .............................................................................................................................................. 7
1.
Scope........................................................................................................................................................... 8
2.
Normative references .................................................................................................................................. 8
3.
Definitions and abbreviations ....................................................................................................................10
3.1 Definitions .........................................................................................................................................10
3.2 Abbreviations ....................................................................................................................................11
4.
Environmental ............................................................................................................................................12
4.1 General .............................................................................................................................................12
4.1.1 Supervision ..........................................................................................................................12
4.1.2 Precautions against damage ...............................................................................................12
4.2 Sanitation .........................................................................................................................................13
4.3 Wildlife ..............................................................................................................................................13
4.4 Access ..............................................................................................................................................13
4.4.1 Use of existing roads ...........................................................................................................13
4.4.2 Construction of new roads ...................................................................................................14
4.4.3 Closure of roads ...................................................................................................................14
4.4.4 Construction of water diversion berms ................................................................................14
4.4.5 Levelling at tower sites .........................................................................................................15
4.5 Gates ................................................................................................................................................15
4.5.1 General ................................................................................................................................15
4.5.2 Installation of gates ..............................................................................................................15
4.5.3 Securing of gates .................................................................................................................15
5.
Line survey ................................................................................................................................................16
5.1 Plans and profiles .............................................................................................................................16
5.2 Setting-out of route ...........................................................................................................................16
5.3 Survey beacons at bend points ........................................................................................................16
5.4 Survey by the Contractor .................................................................................................................16
5.5 Pegging by the Contractor ...............................................................................................................17
5.5.1 Procedure.............................................................................................................................17
5.5.2 Setting out of angle towers ..................................................................................................17
5.5.3 Correct placing of towers .....................................................................................................17
6.
Foundations ...............................................................................................................................................17
6.1 Design and Geotechnical .................................................................................................................17
6.1.1 Foundation design loads ......................................................................................................17
6.1.2 Soil and rock classification ...................................................................................................17
6.1.3 Geotechnical design parameters .........................................................................................18
6.1.4 Soil /rock - foundation nomination .......................................................................................19
6.1.5 Soil and rock tests ................................................................................................................21
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Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
6.2
6.3
6.4
6.5
6.6
6.7
7.
Unique Identifier: 240-47172520
Revision:
5.2
4 of 104
Page:
6.1.6 Drilled foundations, geotechnical design parameters ..........................................................21
Foundation systems .........................................................................................................................23
6.2.1 General ................................................................................................................................23
6.2.2 Pad and pier/column foundations for self-supporting towers ...............................................23
6.2.3 Pad and plinth foundations for guyed tower centre supports ..............................................24
6.2.4 Drilled foundations ...............................................................................................................25
Guy anchors .....................................................................................................................................27
6.3.1 General ................................................................................................................................27
6.3.2 Single inclined drilled pile anchors .......................................................................................28
6.3.3 Foundations for concrete or steel poles ...............................................................................29
6.3.4 Special foundation designs ..................................................................................................29
Concrete and grouts .........................................................................................................................29
6.4.1 General ................................................................................................................................29
6.4.2 Cement types .......................................................................................................................30
6.4.3 Aggregates ...........................................................................................................................30
6.4.4 Workability............................................................................................................................31
6.4.5 Reinforcing steel ..................................................................................................................31
Construction .....................................................................................................................................32
6.5.1 Excavation............................................................................................................................32
6.5.2 Backfilling .............................................................................................................................33
Concrete foundations .......................................................................................................................34
6.6.1 Supply of materials ..............................................................................................................34
6.6.2 Prior to the concrete mix acceptance and placement ..........................................................34
6.6.3 Tolerances for concrete construction ...................................................................................34
6.6.4 Workmanship .......................................................................................................................35
6.6.5 Formwork .............................................................................................................................35
6.6.6 Concrete and grout mixing and testing ................................................................................36
6.6.7 Mixing of concrete ................................................................................................................37
6.6.8 Placement of reinforcing steel..............................................................................................37
6.6.9 Placement of embedded items ............................................................................................37
6.6.10 Placement of concrete .........................................................................................................38
6.6.11 Construction joints ...............................................................................................................39
6.6.12 Concrete surface finish ........................................................................................................39
6.6.13 Concrete curing ....................................................................................................................40
6.6.14 Concrete cracks repair .........................................................................................................40
6.6.15 Steelwork .............................................................................................................................40
Anchor block (deadman), Pile and Rock Anchor testing..................................................................40
6.7.1 Design load (ultimate load) anchor test requirements .........................................................40
6.7.2 Block Guy Anchor (deadman) design load testing criteria ...................................................41
6.7.3 Pile design load testing criteria ............................................................................................41
6.7.4 Rock Anchor design load testing criteria .............................................................................42
6.7.5 Proof load anchor/pile test requirements .............................................................................45
6.7.6 Pole foundations ..................................................................................................................48
Towers .......................................................................................................................................................48
7.1 Tower Design ...................................................................................................................................48
7.1.1 By the Employer ...................................................................................................................48
7.1.2 By the Contractor .................................................................................................................48
7.2 Tower Manufacturing........................................................................................................................49
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240-47172620 (TRMSCAAC 5.2)
7.3
7.4
7.5
Unique Identifier: 240-47172520
Revision:
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7.2.1 Tower code numbers and marking ......................................................................................49
7.2.2 Tower steel standard ...........................................................................................................49
7.2.3 Tower steel fabrication .........................................................................................................50
7.2.4 Steel Bending .......................................................................................................................53
7.2.5 Bolts, nuts and washers .......................................................................................................53
7.2.6 Shackles and extension links ...............................................................................................54
7.2.7 Anti-climbing devices ...........................................................................................................55
7.2.8 Safety Step bolts ..................................................................................................................55
7.2.9 Anti-theft measures and marking .........................................................................................56
7.2.10 Galvanising ..........................................................................................................................56
7.2.11 Welding ................................................................................................................................56
7.2.12 Testing and inspection .........................................................................................................56
Guy ropes and guy attachments ......................................................................................................56
7.3.1 Guy ropes.............................................................................................................................56
7.3.2 Guy attachments ..................................................................................................................56
7.3.3 Fall protection systems ........................................................................................................57
Tower erection ..................................................................................................................................57
7.4.1 Tower material handling and storage ..................................................................................58
7.4.2 Assembly and erection of towers .........................................................................................58
7.4.3 Erection of guyed towers .....................................................................................................58
7.4.4 Tower labels .........................................................................................................................59
Tower Dressing ................................................................................................................................59
8.
Stringing.....................................................................................................................................................60
8.1 Material supply .................................................................................................................................60
8.1.1 By the Employer ...................................................................................................................60
8.1.2 By the Contractor .................................................................................................................60
8.2 Installation of phase and earth conductors ......................................................................................60
8.2.1 Changes in phase configuration ..........................................................................................60
8.2.2 Crossings, notices and permits ............................................................................................60
8.2.3 Handling and stringing of conductors ..................................................................................61
8.2.4 Joints ....................................................................................................................................63
8.2.5 Preparation of metal to metal contact surfaces ...................................................................64
8.2.6 Conductor repairs ................................................................................................................64
8.2.7 Regulating ............................................................................................................................65
8.2.8 Clamping of conductors .......................................................................................................66
8.2.9 Vibration dampers ................................................................................................................67
8.2.10 Multi-conductor spacers and spacer dampers .....................................................................67
8.2.11 Jumpers ...............................................................................................................................68
8.3 Stringing of OPGW ...........................................................................................................................68
9.
Insulators: Handling, Storage, Transport and Installation Practice ...........................................................68
9.1 Receiving ..........................................................................................................................................68
9.2 Storage .............................................................................................................................................68
9.3 Loading and off-loading ....................................................................................................................69
9.4 Transport to site ...............................................................................................................................69
9.5 Insulator Handling ............................................................................................................................69
9.6 Installation ........................................................................................................................................69
9.7 Post Installation ................................................................................................................................70
9.8 Visual Inspection of Insulators .........................................................................................................70
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OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
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6 of 104
Page:
9.9 Tests .................................................................................................................................................70
9.10 Marking, labelling and packaging .....................................................................................................70
9.11 Spares ..............................................................................................................................................71
10. Impedance Measurements ........................................................................................................................71
11. Photographic and Video Records ..............................................................................................................71
Annex A – Details of bolt tolerances .................................................................................................................72
Annex B – Details of safety step bolt ................................................................................................................73
Annex C - Access and ground erosion protection during for overhead line construction ................................74
Annex D - Electrical safety earthing during construction ..................................................................................91
Annex E - Foundation Nomination and Pressure grouted micro piles ...........................................................102
Annex F - Built Documentation Format ..........................................................................................................102
Figures
Figure 1: Alignment of water diversion berms ..................................................................................................77
Figure 2: Typical cross-section of access road requiring cut and fill ................................................................78
Figure 3: Stone pitched outlet berm .................................................................................................................78
Figure 4: Gabion outlet drain ............................................................................................................................79
Figure 5: “Armorflex” type interlocking system for steep access of up to 1:16 .................................................79
Figure 6: Concrete strip road for steep access of up to 1:16 ...........................................................................80
Figure 7: Road Closure in steep terrain ............................................................................................................81
Figure 8: Correct and incorrect methods of cutting stream crossings ..............................................................82
Figure 9: Increasing load bearing capacity using a Cellular Confinement System (Sources: Elmich.com
and Geoproducts.org) ........................................................................................................................82
Figure 10: Water course crossing, with gabion mattresses or rock /gravel filling on geotextile filter
material ...............................................................................................................................................83
Figure 11: River/water course crossing with pipes, rock /gravel mortar filling and concrete slab ....................84
Figure 12: Typical access to self-supporting lattice tower ................................................................................85
Figure 13: Typical access to guyed Tower .......................................................................................................85
Figure 14: Typical access to self-supporting pole ............................................................................................86
Figure 15: Typical 80 ton crane plan dimensions .............................................................................................87
Figure 16: Silt Screen used for rehabilitation of eroded areas .........................................................................89
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Document Classification: Controlled Disclosure
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OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
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Instruction
This Technical Instruction supersedes TRMSCAAC1 Rev 3.
Applicability
This Technical Instruction pertains to all overhead powerlines in Eskom.
It can be used with immediate effect up until the finalised version (TRMSCAAC6) is issued. Any deviations
from this instruction will not be acceptable. If for certain exceptional cases a deviation is deemed necessary,
then this will have to be applied for via the project manager.
This version contains certain improvements and additions from the previous version, and hence must be
studied carefully.
Revision history
This is a new Technical Instruction .
Date
Rev.
Compiled by
Nov 2014
5.2
D Dukhan
W Combrinck
Remarks
Include majority of comments
Development team
RIAZ VAJETH
TECHNICAL AND STRATEGIC GUIDANCE
DAN DUKHAN
DEVELOPMENT TEAM LEADER
QINGBO CAI
STRUCTURAL SPECIALIST
BERTIE JACOBS
TECHNICAL AND STRATEGIC GUIDANCE
VIVENDHRA NAIDOO
TECHNICAL AND STRATEGIC GUIDANCE
NEELS HENDERSON
LINE HARDWARE SPECIALIST
BHARAT HARIDASS
TECHNICAL AND STRATEGIC GUIDANCE
WILLEM COMBRINCK
FOUNDATION SPECIALIST
PIERRE MARAIS
TECHNICAL AND STRATEGIC GUIDANCE
DE WET VISSER
ELECTRICAL ENGINEER
SANJEEV HIRACHUND
LINE SURVEY SPECIALIST
In addition all other Eskom Line Engineering staff, PDD PDP and Distribution staff have contributed. Also all
Eskom staff and contractor staff who have contributed is acknowledged.
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OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
1.
Unique Identifier: 240-47172520
Revision:
5.2
Page:
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Scope
This standard details the requirements for the fabrication, testing, supply, delivery and erection of power line
towers and foundations, together with the stringing of all conductors and associated line hardware and
fittings. This standard is applicable to Transmission Lines only. In the case of towers and foundations,
design aspects are also covered. Certain SHEQ aspects are also covered in this document.
2.
Normative references
The following documents are to be read in conjunction with this standard. In cases of conflict, the provisions
of this standard shall take precedence. Unless otherwise stated, the latest revision, edition and amendments
shall apply.
South African National document(s):
OHSACT &
Act 85 of 1993
REGULATIONS
Fencing Act
Fencing Act No 31 of 1963 as amended.
SAISC
South African steel construction handbook
NEMA
National Environmental Management Act No. 107 of 1998
ECCS
Recommendations for angles in lattice transmission towers, No. 39.
SANS 282
Bending dimensions of bars for concrete reinforcement.
SANS 1089:1991
Round wire concentric lay overhead electrical stranded conductors
SANS 471:1971
Portland cement (ordinary, rapid-hardening and sulphate-resisting).
SANS 60815-1:2009
Selection and dimensioning of high voltage insulators intended for use
in polluted conditions
SANS 626:1971
Portland blast furnace cement.
SANS 675:2009
Zinc-coated fencing wire.
SANS 121:2011/
Hot dip galvanised coatings on fabricated iron and steel articlesspecifications and test methods
(ISO 1461:2009)
SANS 831:1971
Portland cement 15 (ordinary and rapid hardening).
SANS 920:1985
Steel bars for concrete reinforcement.
SANS 1083:1976
Aggregates from natural sources.
SANS 1491-1:1989
Portland cement extenders, Part 1: Ground granulated blast furnace
slag.
SANS 1491-2:1989
Portland cement extenders, Part 2: Fly ash.
SANS 1491-3:1989
Portland cement extenders, Part 3: Condensed silica fume.
SANS 1466:1988
Portland fly ash cement.
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Unique Identifier: 240-47172520
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SANS 2001-CC1:2012
Concrete works (structural)
SANS 2001-CC2:2012
Concrete works (Minor works)
SANS 10100-1:1992
The structural use of concrete. Part 1: Design.
SANS 10100-2:1992
The structural use of concrete, Part 2: Materials and execution of work.
SANS 10144:1978
Detailing of steel reinforcement for concrete.
SANS 10162-1:1993
The structural use of steel, Part 1:
steelwork.
SANS 10162-2:1993
The structural use of steel, Part 2: Limit-states design of cold-formed
steelwork.
SANS 10162-3:1993
The structural use of steel, Part 3: Allowable stress design steelwork.
SANS 10280-1:2013
Overhead power lines for conditions prevailing in South Africa
SANS 5862-1 to 4
Slump of freshly-mixed concrete.
SANS 5863
Compressive strength of concrete (including making and curing of the
test cubes).
SANS 61089 IEC
Round wire concentric lay overhead electrical stranded conductors
Agriculture Bulletin 399
Department of Agriculture Bulletin No. 399 ISBN0621082589, A primer
on soil conservation.
SANS 50025 parts 1 to 6
Hot rolled products of structural steels
Limit-state design of hot-rolled
Eskom National document(s):
32-9: Definition of Eskom documents.
32-644: Eskom documentation management standard.
474-65: Operating Manual of SCOT
474-285
Specification for anti-theft measures
474-9428
Line Impedance measurements
32-247
Procedure for vegetation clearance and maintenance within overhead
power line servitudes and on Eskom owned land.
TSP 41-604
Design, manufacturing and installation specification for transmission
line labels.
TST41-321
Earthing of transmission lines.
NRS 061-2:2004
Specification for overhead
Part 2: Installation guidelines.
NWS 1074
Guy strand grips for transmission lines.
ground
wire
with
optical
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fibre.
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Unique Identifier: 240-47172520
Revision:
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NWP 3402
Power lines in the vicinity of aerodromes and hazards to aircraft.
SHEQ
Eskom SHEQ policy
As Built Specification
To be finalised
International document(s):
ASCE Manual 1097
Guide for design of steel transmission towers
IEC 60826:2003
Design criteria for overhead transmission lines.
DIN EN ISO 898-1:
1999
Mechanical properties of fasteners made of carbon steel and alloy steel. Part
1: Bolts, screws and studs
3.
Definitions and abbreviations
3.1
Definitions
Employer:
The party for whom the works are to be executed and in this standard means
Eskom (Transmission, Distribution, Technology, Power Delivery Projects)
and where applicable, includes Eskom’s appointed successor in title but not,
except with the written content of the Contractor, any assignee of Eskom.
Contractor:
The party appointed by the Employer to “Provide the Works”.
Design Engineer/
Designer:
The person responsible in terms of the “Occupational Health and Safety Act
and Regulations” for the Employer from time to time to act in the capacity and
notified, by name and in writing by the Employer to the Contractor, as
required. He/She shall be ECSA accredited as a professional
Engineer/Technologist. All communication to the design engineer shall be
done via the Project Manager.
Eskom Site
Representative:
The person appointed by the Employer from time to time to act in the capacity
and notified, by name and in writing by the Employer to the Contractor, as
required in “The NEC Engineering and Construction Contract”, FIDIC or any
applicable contract.
Safety Step Bolt:
A step bolt of size M16 and suitable length which is threaded on the one end
for attachment to the tower and an eye on the other end where for example a
climbing harness safety hook can attach onto.
Tower Dressing:
This is the activity during line construction which after tower erection all line
hardware, insulators, running blocks etc. are connected to the tower in
preparation for stringing.
Running Block:
A set of free running pulleys or wheels spaced next to another typically in a
supporting frame which can be attached to a tower in order to temporarily
support the conductors during stringing and regulating operations. This can
also be referred to as a dolly, sheave, stringing block, stringing sheave or
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Unique Identifier: 240-47172520
Revision:
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stringing traveller.
Project Manager
Appointed by the Employer under Act 16.2 & Sect 4h(5) of CR as the client's
Agent to act as his/her representative. The person responsible for coordinating all aspects of a project. All communication must be channelled via
the Project Manager.
Batch:
A specified quantity of samples, components or members.
Lands:
Refers to cultivated land or land set aside for exclusive use.
Line Specification:
A document that specify the requirements for the relevant line, turn-in or bypass that needs to be constructed, refurbished or any other work that may be
required to be executed as part of the project. Specific requirements outlined
in the Line Specification shall take precedence over requirements specified in
this document.
Transverse Face:
See diagram below (as per SANS 10280-1 definition NRS041):
Longitudinal Face:
See diagram below: (as per SANS 10280-1 definition NRS041):
Longitudinal Face
Transverse Face
3.2
Abbreviations
EIA:
Environmental Impact Assessment
Including EA -Environmental Authorisation.
EMP:
Environmental Management Plan
HCP:
Health Care Professional
SHEQ:
Safety, Health, Environmental and Quality
PM:
Project Manager
OPC
Ordinary Portland cement
SRPC
Sulphate resisting Portland cement
SCOT
Steering committee of technology
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4.
Environmental
4.1
General
Unique Identifier: 240-47172520
Revision:
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This section refers to Eskom’s SHEQ policy. All activities relevant to the establishment of power line
construction and design implementation should be undertaken in accordance with the Eskom SHEQ Policy.
Where a discrepancy exists between this document and the SHEQ policy, the SHEQ policy takes
precedence and must be adhered to. The environmental management during the construction activities is to
ensure that the EIA recommendations, the statutory EA Environmental Authorisation Conditions, the EMP,
the landowners Special Conditions and all relevant environmental legislation are implemented, by monitoring
the site works and regular reporting.
In addition please refer to Annex C for further instructions regarding access and ground erosion protection
during overhead line construction.
4.1.1
Supervision
The Contractor shall give or provide all necessary superintendence during the execution of the works. The
Contractor or a competent and authorised appointee approved of in writing by the Project Manager (which
approval may at any time be withdrawn) shall be on the works at all times when work is being performed or
when the Employer shall reasonably require it. The Contractor shall employ only such persons that are
competent, efficient and suitably qualified with related experience in the environmental field. Eskom/ Project
Manager shall be at liberty to object to and require the Contractor to remove from the works any person,
who, misconduct’s himself or is incompetent in the proper performances of his duties.
4.1.2
Precautions against damage
a)
In accordance with applicable legislation, the Contractor shall take all reasonable precautions for
the protection of life and property on, or about, or in connection with the works.
b)
The Contractor shall comply strictly with the “Special Conditions” stipulated by the landowners in
the negotiated Options.
c)
The Contractor shall comply with all the conditions specified in the Environmental Management
Plan (EMP) during construction. In general, soil disturbance should be kept to a minimum. The
disturbance of land contour banks or other erosion control structures shall be avoided.
d)
No damage shall be caused to any crops unless both the landowner and the Eskom Site
Representative, prior to the work commencing agree upon the extent of the intended damage.
e)
There shall be no littering of the veld. The Contractor shall provide suitable containers for any
waste.
f)
No fires shall be allowed on site under any circumstances.
g)
The Contractor shall be held liable for all damage arising from actions or negligence on the part of
his workforce and any such damage shall be repaired immediately.
h)
Any additional agreement concluded between the Contractor and a landowner not relating to
Providing the Works, must be in writing and a copy made available to the Eskom Site
Representative within 48 hours of such an agreement being concluded.
i)
Any environmental incident as specified in the EMP, or accident during construction of the works
shall be immediately reported to the Eskom Site Representative.
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4.2
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Sanitation
The Contractor is to provide portable toilet facilities for the use of his workforce at all work sites. Under no
circumstances shall use of the veld be permitted. To prevent the occurrence of measles in cattle, employees
may require to be examined for tapeworm and treated, or treated irrespective of whether they are infested or
not. Proof of such treatment is to be supplied to the Eskom Site Representative. The drug “Niclosamide”
(Yomesan, Bayer) is freely available and highly effective against tapeworms in humans. A HCP should be
consulted prior to administering. It does not however, prevent re-infestation and regular examination and/or
treatment is required.
4.3
Wildlife
a)
It is illegal to interfere with any wildlife, fauna or flora as stipulated in the Environmental
Conservation Act No 73 of 1989.
b)
When stipulated in the EMP, two different coloured bird diverters are to fitted on both earthwires
(where applicable) along the indicated spans at 5m intervals.
4.4
Access
a)
The Contractor, and ECO shall negotiate with each landowner the access to reach the servitude
and each tower position. The access agreement will be formalised in the form “TPL 004/005 Property Access Details” and signed by the three parties. The Contractor will mark the proposed
route and/or a competent representative will accompany the equipment when opening the access.
Any deviation from the written agreement shall be closed and re-vegetated immediately.
b)
The Contractor shall signpost the access roads to the tower positions, immediately after the
access has been negotiated.
4.4.1
Use of existing roads
a)
Maximum use of both the existing servitudes and the existing roads shall be made. In
circumstances where private roads must be used, the condition of the said roads must be recorded
prior to use (e.g. photographed) and the condition thereof agreed by the landowner, the Eskom
Site Representative and the Contractor.
b)
All private roads used for access to the servitude shall be maintained by the Contractor and upon
completion of the works, be left in at least the original condition.
c)
Access shall not necessarily be continuous along the line, and the Contractor must therefore
acquaint himself with the physical access restrictions such as rivers, railways, motorways,
mountains, etc. along the line. As far as possible, access roads shall follow the contour in hilly
areas, as opposed to winding down steep slopes.
d)
Access is to be established by vehicles passing over the same track on natural ground, multiple
tracks are not permitted.
Access roads shall only be constructed where necessary at
watercourses, on steep slopes or where boulders prohibit vehicular traffic.
e)
The Contractor is to inform the Eskom Site Representative before entering any of the following
areas:
f)
Naturally wet areas: vlei, swamps, etc.
g)
Any area after rain.
h)
Any environmentally sensitive area.
i)
If access is across running water, the Contractor shall take precautions not to impede the natural
flow of water. If instructed, the Contractor is to stone pitch the crossing point. There shall be no
pollution of water. Access across running water and the method of crossing shall be at the
approval of the Eskom Site Representative and the landowner.
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j)
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Where the Eskom Site Representative and/or Project Manager, deems that damage to the
access roads is irreparable, the Contractor shall use alternative construction methods compatible
with the access and terrain, as agreed with the Project Manager.
k)
Existing water diversion berms are to be maintained during construction and upon Completion be
repaired as instructed by the Eskom Site Representative.
l)
Where access roads have crossed cultivated farmlands, the lands shall be rehabilitated by ripping
to a minimum depth of 600mm.
4.4.2
Construction of new roads
a)
Where construction of a new road has been agreed, the road width shall be determined by need,
such as equipment size, and shall be no wider than necessary.
b)
In areas over 4% side slope, roads may be constructed to a 4% out slope. The road shall be
constructed so that material will not be accumulated in one pile or piles, but distributed as evenly
as possible. The material shall be side-cast as construction proceeds, and shall not be side-cast
so as to make a barrier on the downhill side. The cut banks shall not overhang the road cut, and
shall if necessary be trimmed back at an angle which would ensure stability of the slope for the
duration of the works. The sides or shoulders of roads shall not act as a canal or watercourse.
c)
Water diversion berms shall be built immediately after the opening of the new access road. In
addition, water outlets shall be made at intervals where berms are installed, and suitably stone
pitched if instructed by the Eskom Site Representative.
d)
No cutting and filling shall be allowed in areas of 4% side slope and less.
e)
Existing land contours shall not be crossed by vehicles and equipment unless agreed upon, in
writing, by the landowner and the Eskom Site Representative.
f)
Existing drainage systems shall not be blocked or altered in any way.
4.4.3
Closure of roads
a)
Upon completion, only roads as indicated by the Eskom Site Representative shall be closed.
b)
In areas where no cut or fill has been made, barriers of earth, rocks or other suitable material shall
effect closure.
c)
In areas 30 % slope and less, the fill of the road shall be placed back into the roadway using
equipment that does not work outside the road cut (e.g. back-hoe). In areas of greater that 30 %
slope, the equipment shall break the road shoulder down so that the slope nearly approximates to
the original slope of the ground. The cut banks shall be pushed down into the road, and a near
normal side slope shall be re-established and re-vegetated.
d)
Replacement of earth shall be at slopes less than the normal angle of repose for the soil type
involved.
4.4.4
Construction of water diversion berms
a)
Water diversion berms shall be spaced according to Annex C.
b)
Where the in-situ material is unsuitable for the construction of water diversion berms, alternative
methods of construction must be investigated and proposed by the Contractor and submitted to the
Project Manager for acceptance.
c)
Borrow pits - The Contractor’s decision as to the location of borrow pits, shall be at the Eskom
Site Representative’s acceptance. The Contractor shall be responsible for the rehabilitation and
re-vegetation of the borrow pits. It is the Contractor’s responsibility to negotiate the royalties for
the borrow pits with the landowner.
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4.4.5
Levelling at tower sites
a)
No levelling at tower sites shall be permitted unless approved by the Eskom Site Representative.
b)
The steep slopes formed by the cut banks and respective fillings when building the tower platforms
are to be trimmed back to an angle that ensures stability of the slope. When the ground is loose,
berms are to be built on the top of the slope, 2m long logs spaced evenly must be pegged across
the down-slope, re-vegetated with appropriate local grass seeds together with fertiliser.
4.5
Gates
4.5.1
General
a)
Attention is drawn to the Fencing Act No. 31 of 1963 as amended, in particular with regard to the
leaving open of gates and the dropping of fences for crossing purposes, climbing, and wilful
damage or removal of fences.
b)
At points where the line crosses any fence in which there is no suitable gate within the extent of the
line servitude the Contractor is to, on the Eskom Site Representative’s instruction, provide and
install a servitude gate as detailed in the relevant drawing. The Contractor will mark these
crossing points when the tower positions are being pegged.
c)
Where applicable game gates are to be installed in accordance with the relevant drawing.
d)
All vehicles shall pass through gates when crossing fences and the Contractor shall not be
allowed to drop fences temporarily for the purpose of driving over them. No construction work shall
be allowed to commence on any section of line, unless all gates in that section have been installed.
Installation of gates in fences on major road reserves shall comply with the ordinances of the
relevant Provincial Authority. No gates may be installed in National Road and Railway fences.
4.5.2
Installation of gates
a)
Care shall be taken that the gates shall be so erected that a gap of no more than 100mm to the
ground is left below the gate.
b)
Where gates are installed in jackal proof fencing, a suitable reinforced concrete sill as shown on
the drawing shall be provided beneath the gate.
c)
The original tension is to be maintained in the fence wires.
d)
Where required, the Contractor shall replace rusted or damaged wire strands on either side of the
gate with similar new wiring to prevent the movement of animals. The extent of the replacement
shall be on the Eskom Site Representative’s instruction.
e)
Where existing servitude gates are used, they must be refurbished to the latest standard for gates
as per the latest approved gate drawings.
4.5.3
Securing of gates
a)
The Contractor shall ensure that all servitude gates used by him are kept closed and locked at all
times.
b)
The Contractor shall provide locks for all servitude gates, and when the line is taken over these
locks shall be recovered by the Contractor and replaced by locks supplied by the Employer. The
Contractor shall also ensure that all existing farm gates used by him are kept closed. The
Contractor shall provide the Eskom Site Representative with keys for the above locks. No keys
shall be provided to landowners to avoid conflict situations between neighbouring landowners.
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5.
Line survey
5.1
Plans and profiles
Unique Identifier: 240-47172520
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The route of the line will be surveyed by the Employer, who will provide all necessary route plans and
templated profile drawings, on which, tower types and the position thereof will be indicated.
Position of aircraft warning spheres, bird guards, bird flights diverters and other site-specific environmental
considerations will be indicated on the construction profiles.
5.2
Setting-out of route
The line route will be set-out by the Employer prior to the commencement of construction. Bend positions
are to be demarcated with iron pegs, set in concrete and clearly labelled as per approved profile. The
diameter of the iron pegs must not be less than 16 mm with 20 mm diameter preferred in rural areas. To
ensure visibility of bend positions a cairn of stones must be placed around the peg and white washed. The
route must further be demarcated by online reference stakes at least 1,2 m high and at approximately 2 km
intervals and should in most cases be inter-visible.
5.3
Survey beacons at bend points
At bend positions, the original iron pegs indicating the centre line of the transmission line route are on no
account to be disturbed or removed, as these are required for servitude registration purposes. During
foundation installation, the Contractor is to cast the bend pegs in position with concrete.
5.4
Survey by the Contractor
a)
The pegging of tower positions, and where necessary, the establishing of self-supporting tower leg
extensions and guy anchor positions for guy towers, shall be carried out by registered surveyors.
b)
The Contractor, on completion of each 20 km or suitable section of the line, is to supply records of
all distances measured for each individual tower position. These should agree with the profiles, and
any discrepancy reported immediately to the Design Engineer via the Project Manager.
c)
It is the Contractor’s responsibility to inform the Eskom Site Representative immediately, should
d)
1)
there be any discrepancy between the topography shown on the profiles and the actual
ground;
2)
errors be found, for example where a tower position is physically in “lands” and the profile
states "no-tower zones";
3)
Any new or existing features or other services either above or below the ground be found
and which are not reflected on the line profiles. This includes land use, roads, telephone or
power lines and pipelines/irrigation equipment which may adversely affect tower positions
and/or statutory clearance requirements.
4)
The Contractor, in his opinion, finds that the site chosen is not suitable for a tower
position, or the tower type indicated on the profiles is not suitable for the tower position e.g.
excessive side slope.
It is the Contractor's responsibility to ensure that the surveyor is familiar with the limitations and
restrictions of the tower types and construction methods used.
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5.5
Pegging by the Contractor
5.5.1
Procedure
a)
The Contractor shall undertake the pegging of the transmission line tower positions along the
intended line route. Pegging shall proceed far in advance of foundation nomination and
construction.
b)
Tower centre position is to be marked with a steel peg not more than 50 mm high. This peg is to
be made clearly visible by a stake driven into the ground (1.2 m high) or by rocks, both painted
white. The pegs are to carry a tag showing the tower number, tower type and height. The pegs are
to be left in position until the tower is erected.
5.5.2
Setting out of angle towers
All angle towers shall be positioned in such a way that the centre phase conductor is on the centre line of the
servitude. Off-setting of towers may be required to achieve this. The amount of off-set can be obtained from
the relevant tower drawings or by calculation.
5.5.3
Correct placing of towers
It is the Contractor’s responsibility to ensure that accepted survey methods are used, and that checks are
done to ensure the correct placing of towers.
NOTE: As numerous numbers appear on the profile drawings, the Contractor is to ensure that the actual span
distances add up to the length of the straight or section of line between two bends. Any distance which are shown
from a line point to a tower are to be taken as unchecked.
6.
Foundations
6.1
Design and Geotechnical
6.1.1
Foundation design loads
All foundations shall be designed to the ultimate load as per the relevant line/project standard.
It is the Contractor’s prerogative to use Eskom-issued standard foundation designs(for tender purposes) or
supply his own design for acceptance by Eskom. In the former and latter cases, the design accountability
rests solely with the Contractor.
6.1.2
Soil and rock classification
a)
Hard Rock: hard to very hard solid or moderately fractured continuous solid rock, and including
hard to very hard rock of any other description which meets the strength requirements of clause
6.1.3.
b)
Soft Rock: weathered or decomposed soft continuous fractured rock but not very/extremely
fractured and including rock of any other description which meets the strength requirements for
classification under clause 6.1.3.
c)
Type ‘1’ soils: competent soil with equal or better consistency (strength or toughness) than one
would encounter in stiff cohesive soils or dense cohesionless soils above the water table. This soil
shall has a broad balanced texture (constituent particle sizes) with high average combinations of
undrained shear strength and internal angle of friction, with minimum values of 80kN/m² and 30°
respectively. The minimum dry specific weight ( dry density) shall not be less than 1700 kg/m³.
d)
Type ‘2’ soils: a less competent soil than type "1", with equal or less consistency than one would
encounter in firm to stiff cohesive soils, or dry poorly graded medium dense to dense cohesionless
soils above the water table. This soil has a dominating texture of clay or sand and silt and with
minimum undrained shear strength of 40kN/m². The minimum dry specific weight (dry density) shall
not be less than 1550kg/m³.
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e)
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Type ‘3’ soils: dry loose cohesionless soil or very soft to soft cohesive soil. Where excavated
material does not provide the required backfilling for the foundation type, methods of soil
improvement as per clause 6.5.2 i) shall be considered. If a very pebbly/stony soil or boulders are
encountered these must be disposed of as per clause 6.5.2.j), then use imported backfill.
f)
Type ‘4’ soils: less competent submerged cohesion and cohesive less soils below the
permanent water table, including soils below a re-occurring perched water table, or permeable soils
in low-lying areas subjected to confirmed (known) seasonal flooding. This will be very permeable
water bearing soils where strong seepage water is encountered in the investigation pits.
6.1.3
Geotechnical design parameters
a)
For rock
Parameters
Soft rock
Hard rock
800 kPa.
2 000 kPa.
37º
45º
135 kN/m²
350 kN/m²
(R1-R2) Indentations of 1-3 mm
shown in the specimen with firm
blows of the geological pick point.
Can just be scraped with a knife.
(R3-R4)Handheld specimen can
be broken with hammer end.
Cannot be scraped or peeled with
a knife.
Maximum toe bearing
pressure at foundation
depth
Rock Frustum angle
Skin shear friction concrete to rock
SANS 10161
descriptions
b)
For Soil types 1 and 2
Parameters
Type ‘1’
Type ‘2’
Maximum soil bearing
pressure
300 kPa
150 kPa
Maximum toe bearing
pressure
375 kPa
200 kPa
30º
20º
Frustum angle for strain
towers (factored)
30º x0.83=25º
20º x0.75=15º
Undrained shear
strength (Interface
friction concrete to soil)
80 kN/m²
40 kN/m²
Minimum dry Density
1700 kg/m3
1550 kg/m3
Density of reinforced
concrete
2400 kg/m3
2400 kg/m3
Frustum angle for
suspension towers
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Parameters
SANS
descriptions
c)
10161
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Type ‘1’
Type ‘2’
COHESIVE SOIL (S4-S5)
Slight indentation produced by
pushing Geologist pick point into the
soil. Cannot be moulded by fingers.
Hand pick required for excavation.
COHESIVE SOlL (S3)
Sharp end of Geologist pick can be
pushed into the soil up to 10mm.
Can just be penetrated with an
ordinary spade.
COHESIONLESS SOlL
Very high resistance to penetration
of sharp end of geological pick.
Requires many blows by a hand
pick for excavation.
COHESIONLESS SOIL
Considerable resistance to
penetration by sharp end of
geological pick. Considerable
resistance to shovelling.
For Soil types 3 and 4
Parameters
Type ‘3’
Type ‘4’
Maximum soil
bearing pressure
100 kPa
50 kPa
Maximum toe
bearing pressure
125 kPa
65 kPa
Frustum angle for
suspension towers


Frustum angle for
strain towers


Minimum dry Density
1400 kg/m3
1000 kg/m
Density of reinforced
concrete
2400 kg/m3
1400 kg/m3
COHESIVE SOlL (S2-S1)
Sharp end of Geologist pick can be
pushed into the soil 30 to 40 mm.
Moulded by fingers with some pressure.
No resistance to shovelling.
Type 4 is a condition i.e. waterlogged
or submerged foundation conditions.
This includes all soils below the
permanent water table, including soils
below a reoccurring perched water
table, or permeable soils in low-lying
areas subjected to confirmed (known)
seasonal flooding.
SANS 10161
descriptions
COHESIONLESS SOlL
Small resistance to penetration by
sharp end of geological pick.
3
NOTE: For maximum soil bearing pressure and maximum toe bearing pressure, use the tabled
pressure or 80% of the ultimate tested bearing pressure determined from appropriate tests.
6.1.4
Soil /rock - foundation nomination
a)
The Contractor shall be responsible for the soil/rock investigation and shall delegate this work to
an experienced registered professional duly authorised to do so on behalf of the Contractor and,
who shall accept the responsibility for all the foundation test pit investigations and the foundation
type nominations for the corresponding soil profiles. The signed foundation-soil type nomination list
and Contractor’s soil profile log sheets shall be submitted to the Design Engineer for acceptance.
All soil profiling investigations shall be done in the presence of the Eskom Site Representative.
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b)
The minimum soil investigation requirement shall be the number of test pit excavations as per the
illustration shown in Annex E, to allow for the in-situ inspection of the soil. Recording thereof shall
be on the Eskom’s soil profile and summary sheets(Annex E), of all the foundation-soil type
assessments. Soil profiling standards shall be in accordance with SANS 10161 (i.e. each
stratum/layer must be described in terms of MCCSSO). The test pits shall be excavated outside the
zone of influence of the appropriate foundation, and shall be taken down to a depth equal to the
lesser of the depth of the foundation system to be constructed or 3m. In addition, appropriate soils
tests as described in clause 6.1.5 shall be carried out where further clarification is required for the
correct identification of a soil category. No concession shall be granted by Eskom with a view to
reduce the number of test pits excavated. The soil/ rock foundation type nominations based on the
aforementioned procedures shall take place well in advance of actual foundation installation, so as
not to disrupt construction activities, and to allow for the possibility of having to conduct laboratory
tests on border case or mix layer type soils and/or rocks.
c)
Due to the fact that combinations of two or more of the soil or rock classifications as described in
clause 6.1.2 and 6.1.3 could occur at any one foundation position, including rock boulders in a soil
matrix, the soil or rock nomination in terms of one of the six classifications in clause 6.1.2 shall
then be conservatively based on the load transfer capability in terms of clause 6.1.3 of the soil
and/or rock encountered over the depth of influence of the approved foundation system. For
example, a combination of a type ‘1’ soil and soft rock over the depth of influence of an approved
type ‘1’ soil foundation design shall be nominated as a type ‘1’ soil condition and the approved
type‘1’ soil foundation system shall be installed. By following this procedure, the soil or rock
nomination at each foundation position shall be one of the six classifications as described in clause
6.1.1 and this shall in turn define which foundation type and system design is to be installed.
d)
The test pit shall be suitably backfilled and levelled immediately after the relevant inspections and
tests have been completed.
e)
Should the foundation conditions at the actual foundation location be found to differ from those
identified at the corresponding test pit, the Contractor shall immediately inform the Eskom Site
Representative and a revised assessment made. The acceptance by the Eskom Design
Engineer of the soil type foundation nomination shall not relieve the Contractor of this
responsibility. When actual excavation conditions differs from test pit data, and rock or large
boulders are encountered at depth, special rock foundations should be designed incorporating the
existing rock and/or large boulder(s) as part of the foundations.
f)
In waterlogged cases, 2 or more pumps must be used at sumps in the excavation bottom corners
to lower the water level allowing installation. The use of well-points method (pumping water out)
around the foundation to lower the water level must be investigated before specialised foundations
will be considered.
g)
Where site conditions, such as difficult conditions access or environmentally sensitive areas are
encountered, i.e. water courses, waterlogged areas, slopes with erodible dispersive soils etc., an
additional more detailed investigation of the area shall be done by the Contractor and acceptance
of the proposed procedures shall be obtained from Line Engineering.
h)
Pressure Grout Injected Micro Piles geotechnical investigation
Where specialised grout injected anchor foundation systems is being installed a more applicable
geotechnical investigation for this type of anchor must be done with minimum requirements entailing the
following:
 An investigative hole must be drilled next to foundation to be installed and flushed with water only,
in order to establish the geotechnical conditions. From the changes of drilling rates the depths and
consistency of layers, can be determined.
 The rate of drilling and continuous grout pressure must be recorded for each hole drilled, including
all installation information that is: anchor type, size, diameter, depth, etc.
 From the pumped out suspension some characteristics of the soil/rock can be determined and
recorded for the layers as encountered. That is:
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For soil: 1) a clay or sandy soil, 2) hard or soft soil, 3) the colour etc.,
For rock: 4) hard or soft rock, 5) flushed out as powder, chips or sandy grains, 6)colour etc.
 All this information must be logged (see inspection sheets See Appendix F) for every drilled hole of
the foundation. If there are differences between the investigation hole and the actual anchor holes
of the foundation, a further investigation hole on the opposite side of the foundation can be drilled
to determine more accurate information of the geotechnical conditions.
 Soil frictional /shear values and or strengths and other geotechnical conditions influencing the
anchor performance shall be confirmed by a minimum of 10% anchor tests as per specification
before foundation installation commence.
6.1.5
Soil and rock tests
a)
In addition to the minimum soil/rock investigation requirements, tests shall be carried out by the
Contractor, if so required by the Design Engineer, to confirm a soil or rock type classification and
shall be conducted in accordance with accepted, good geotechnical engineering practices, and
shall include but not be limited to the following:
1)
Standard penetration tests or Dutch Cone penetrometer tests.
2)
Visual classification of soils.
3)
Determination of present and probable water table level.
4)
Laboratory and/or site tests to determine soil friction angles and cohesion values.
5)
Laboratory tests to determine stress-strain modules of soils and rock.
6)
Laboratory and/or site tests to determine soil unit weights.
7)
Laboratory and/or on site tests to determine the soil texture i.e. whether the soil is
predominantly clay, silt, sand or gravel.
8)
Continuous rock cores with recovery values and drilling times.
The standard penetration tests and recovery of soil samples shall be obtained in each soil strata
encountered or at 1.5 m intervals, whichever is less. Rock cores shall extend a minimum of 3.5 m
into sound rock.
b)
The soil/rock investigation shall be conducted to recognised standards to ensure that all
encountered soil and/or rock strata are identified and delineated by area along the line route. It
shall be the Contractor's responsibility to perform adequate soil/rock investigations to the
satisfaction of the Eskom Design Engineer to determine the soil/rock suitability at each site.
6.1.6
Drilled foundations, geotechnical design parameters
Soil /rock design parameters for final design and construction of drilled foundations shall be determined by
pile tests, foundation tests or comprehensive soil /rock investigations as described in clause 6.1.5. The
Contractor is fully responsible for the final foundation designs. As a guide only, "average" parameters are
set out below.
a)
In type ‘1’ or type ‘2’ soils, a skin friction with a maximum of 80 kPa in a type ‘1’ soil, and a
maximum of 40 kPa in a type ‘2’ soil, may be used. The skin friction values that are used shall not
exceed 80% of the ultimate friction determined from appropriate soil tests in accordance with
clause 6.1.2-3.
b)
In soft rock, when non-shrink grout or concrete is utilised, a maximum skin friction of 135 kPa may
be used in all piles or anchors. A 37° frustum shall be used to check an anchor group pull out
resistance. The skin friction value shall not exceed 80% of the ultimate friction determined from
appropriate rock tests in accordance with clause 6.1.2-3.
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In hard rock, when non-shrink grout or concrete is utilised, a maximum skin friction of 350 kPa may
be used in anchors with a maximum diameter of 150 mm. A 45° frustum shall be used to check
anchor group pull out resistance. The skin friction value shall not exceed 80% of the ultimate
friction determined from appropriate rock tests in accordance with clause 6.1.2-3.
c)
d)
The depth of any pile(s) in a pile group in soils shall be so calculated to resist the uplift force on the
pile or pile group. For a type ‘1’ soil, a 30° frustum for suspension towers, and a 25° frustum for
angle strain towers may be assumed. Similarly for a type ‘2’ soil, a 20° frustum for suspension
towers, and a 15° frustum for angle strain towers may be assumed. Assumed material densities to
be as per clause 6.1.2-3.
e)
No horizontal shear resistance on the piles or pile cap shall be assumed for re-compacted
excavated soil. The lateral resistance of undisturbed soil shall be ignored in the top 300mm from
ground line, and taken as the lesser of 100kPa or 80% of the permissible bearing determined from
appropriate tests from 300mm below ground level to the bottom of the pile cap. If the pile cap is
not capable of restraining the entire horizontal base shear, the piles and pile cap shall be designed
to resist the shears and moments introduced from the pile cap to the individual piles. A soil bearing
pressure of 200kPa in type ‘1’ or 100kPa in type ‘2’ soil shall be allowed under the pile cap. End
bearing components for compressive loads shall not be considered in soil replacement type piles
with a diameter less than 750mm.
6.1.7
Strength factors for foundation systems
For overhead lines supporting voltages in excess of 132kV (Reliability level 2 and higher), the determination
of appropriate design loads for foundations will consider Failure Sequencing strength factors as defined in
SANS 10280-1, Table 2.
For overhead lines of 132kV and lower (Reliability level 1), the use of failure sequencing strength factors is at
the Design Engineer’s discretion.
A factored foundation design load may be determined by the inverse of the relevant strength factor for a
particular foundation system as indicated in the following table:
Characteristic strength (Rc)
Foundation Type
determined by
Strength factor
application (s)
Planted pole foundations or caisson
Maximum overturning capacity of footing
1,0
Foundations in compression only
Maximum compressive load capacity of
footing
0,9
Foundations for self-supporting structures (in
overturning, compression and tension)
Maximum compressive or tensile load
capacity of footing
0,83
Guy anchor
foundations for
guyed
monopoles and guyed vee structures
Maximum tension capacity of footing
0,75
Maximum tension capacity of footing
0,7
Maximum tension capacity of footing
0,65
Inclined piles in guyed structures
1
Permanently loaded guy anchor foundations
on strain towers
1
For specialist piles such as continuous flight augured, precast driven, and piles with shaped under reams or bulbs – use
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6.2
Foundation systems
6.2.1
General
Unique Identifier: 240-47172520
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a)
Before foundation excavation commences the Contractor shall submit to the Project Manager
drawings and relevant design calculations of all the proposed foundations intended to be use for
acceptance by the Design Engineer. Acceptance by the Design Engineer does not relieve the
Contractor of his responsibility for the adequacy of the design, dimensions and details. The
Contractor shall be fully responsible for his designs and their satisfactory performance in service. A
registered Civil Engineer or Civil Engineering Technologist, duly authorised to do so on behalf of the
Contractor, shall accept responsibility for all foundation designs and drawings submitted to the
Design Engineer, and shall sign all drawings accordingly. If the Employer provides foundation
designs and/or drawings, a registered Civil Engineer or Civil Engineering Technologist, acting on
behalf of the Contractor, shall check and assume responsibility for such designs and/or drawings.
All foundation design loads are to be shown on the relevant foundation drawing.
b)
No foundation shall be constructed without the Design Engineer acceptance. All drawing
revisions shall be submitted to the Design Engineer before being issued for construction
purposes.
c)
Only with the specific permission of the Design Engineer, may more than one design per soil or
rock type of any foundation system for a tower type be utilised.
d)
A ground slope of up to and including 12 degrees to the horizontal in any direction shall be
assumed at all foundation positions for design purposes.
e)
No grillage or steel plate type foundations are allowed.
6.2.2
Pad and pier/column foundations for self-supporting towers
a)
The foundations shall be designed to withstand, with less than 20 mm of differential settlement or
displacement, the maximum foundation reactions resulting from the withstood loadings stated in
the Works Information, with the dead weight of the tower included at unity factor of safety.
b)
The foundations shall be designed for the maximum combinations of compression, uplift and
horizontal shear forces. In addition, a 250 mm minimum and 650 mm maximum projection of the
pier and stub above ground level shall be incorporated in the design unless special approval has
been granted by Eskom. The stub only is to be encased in concrete; the tower steel above the
diagonal members is not to be encased.
c)
All concrete subjected to tension, where the permissible tensile stress is exceeded, shall be
adequately reinforced with deformed reinforcing steel bars. The design shall be in accordance with
the requirements of SANS 10100. The maximum permissible tensile stress in the concrete shall be
1.75 MPa. Piers shall be reinforced for their full length with the reinforcing properly anchored in the
pad. The minimum number of longitudinal vertical bars provided in a pier shall be four 16 mm
diameter bars with a minimum yield stress of 450 MPa. The links shall be 10mm diameter minimum
mild steel bars at a maximum spacing of 300mm.
d)
Pads designed with a 45° plinth only may be utilised. All faces of such a core where the permissible
tensile stress in the concrete is exceeded is to be adequately reinforced to prevent the
development of tension cracks.
e)
The foundation shall be designed to resist the vertical compression load at the bottom of the
foundation. The foundation shall be checked to ensure that "punch-through" of the stubs shall not
occur. The maximum soil bearing pressure allowed due to the vertical compressive load, plus the
mass of the foundation, less the mass of the soil displaced by the foundation, shall not exceed the
values specified in clause 6.1.3 for the soil type involved.
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f)
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In addition to the vertical compression and tension loadings, the foundations shall be designed for
the overturning moment and resultant soil toe pressure due to the remaining horizontal base
shears applied at the top of the foundation, including the maximum foundation projection. The
maximum soil toe pressure shall not exceed the value specified in clause 6.1.3 for the soil type
involved.
g)
The foundation shall be designed to resist the vertical uplift load, by means of the mass of the
foundation plus the nett mass of the soil frustum acting from the bottom of the foundation base.
Bracing shear forces shall be considered in the pier design of towers.
h)
The structural steelwork shall be firmly keyed into the concrete by means of adhesion between
steel and concrete and bolted-on cleats. The load shall be transferred by means of bolted-on cleats
where the bolts shall have no thread in the shear planes. The cleats shall be so positioned on the
structural steel member, so as to limit punching shear in the concrete due to both tension and
compression load cases. When calculating the number and size of cleats required the maximum
contact pressure between cleat and concrete shall not exceed 10MPa. The number of cleat bolts
required shall be calculated for the ultimate shear stress with no thread in the shear plane.
Galvanising of stubs and cleats shall be in accordance with SANS 121:2011 / ISO 1461.
Galvanising thickness to be minimum 105 microns.
i)
The least lateral dimension ’d’ of a pier/column shall not be less than the greater of 400mm or L/5,
where 'L' is the lesser of the vertical height measured from top of pad level to the top of the
concrete pier, or the vertical height measured from founding level to the top of the concrete pier
when a pad is not utilised. For circular pier sections ’d’ represents the diameter and for square or
rectangular sections ’d’ represents the length of the shortest side.
6.2.3
Pad and plinth foundations for guyed tower centre supports
a)
The foundations shall be designed to withstand, with less than 20 mm of settlement, the maximum
foundation reactions resulting from the loadings stated in the standard, with the ultimate load.
b)
The minimum depth of the mast support foundation(s) shall be 750 mm in type ‘1’ and type ‘2’ soil,
and 1000 mm in type ‘3’ and type ‘4’ soil. The soil at the bottom of the foundation shall resist all
stresses resulting from the vertical compressive loads and toe pressures due to horizontal shear
forces. The mass of the foundation less the mass of the soil displaced by the foundation shall be
included in the vertical load applied. The maximum soil toe pressure shall not exceed the values
specified in clause 6.1.3.
c)
The foundations shall be designed for the maximum combinations of compression and horizontal
shear forces. In addition, a 1500mm projection of the plinth above ground level in the case of cross
rope suspension type towers, and a 650mm projection in the case of guyed ‘V’ type towers, shall
be incorporated in the design to allow for leg extension increments.
d)
All concrete subjected to a tension where the permissible tensile stress is exceeded, shall be
adequately reinforced with steel reinforcing bars in compliance with SANS 920. The design shall be
in accordance with the requirements of SANS 10100.
e)
Anchoring of the tower bases of guyed “V” towers shall be by means of anchor bolts. The
maximum shear on anchor bolts shall be 0.6 times the ultimate tensile strength of the bolt. If the
anchor bolts must resist compression loads from the base plate, the compression load shall be
resisted by mechanical anchorage, and not by adhesion between steel and concrete, unless
deformed bars are utilised for anchor bolts.
f)
In some cases of soil type 1 to 4 pad foundations where rock is encountered at shallower depth than
required by the soil foundation, a combination of rock anchors (to provide the additional uplift
resistance) can be utilised.
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6.2.4
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Drilled foundations
The Contractor shall have equipment for, and personnel knowledgeable and experienced in, the evaluation
and construction of this type of foundation.
a)
b)
General
1)
The Contractor shall allow for the testing of two separate piles/anchors in each of the soil
or rock types for which they have been designed. Pile/anchor tests as described in clause
6.7 if so required by the Design Engineer, are to be successfully tested to the Design
Engineer’s satisfaction prior to construction of cast-in-situ pile/anchor foundations.
2)
All design clauses in 6.1.3 relating to drilled concrete foundations shall apply.
3)
Piles shall be designed to limit ground line vertical deflection, at maximum loadings, to less
than 12 mm.
4)
The minimum centre to centre spacing of any two piles in a group of piles shall be three
pile diameters of the pile with the larger diameter, unless otherwise accepted by the
Design Engineer.
5)
The structural steelwork shall be firmly keyed into the concrete by means of bolted-on
cleats. The adhesion between steel and concrete shall not be relied upon to transmit the
load to the foundation. The cleats shall be so positioned on the structural steel member, so
as to limit punching shear in the concrete due to both tension and compression load cases.
When calculating the number and size of cleats required the maximum contact pressure
between cleat and concrete shall not exceed 10MPa. The number of cleat bolts required
shall be calculated in accordance with SANS 10162-1: 2005.
6)
Pile caps shall have a minimum thickness and width of 750mm for loads above 400kN.
Single cast-in-situ piles
Foundations utilising one cast-in-situ concrete pile will be considered by the Design Engineer if
the following criteria are met:
1)
If a pile cap is not utilised, the pile shall have a minimum diameter of 350 mm in order that
the structural steel attachment of the tower can be accommodated without conflict with the
reinforcing steel. The option of raking with the correct set to reduce shear may be
considered should a pile cap be utilised, the minimum pile diameter shall be 300 mm.
2)
The pile shall be constructed vertically, and shall be designed for the maximum
combinations of uplift and compression loadings, and the total horizontal base shear forces
associated with the vertical loadings. Total horizontal shear applied at the top of the
foundation, including the 650 mm maximum projection above ground level, is to be
included. Lateral load design bending moments shall be calculated taking into account
possible plastic soil deformation. Raked piles will be accepted upon submission of all
method statements and review of calculations and drawings by the Design Engineer for
acceptance.
3)
The pile shall be designed to ensure that it acts as a rigid pile. Horizontal deflection at the
top of the projected pile under ultimate loading shall be limited to 5 mm.
4)
Single in line guy anchor piles shall only be designed for type 1 soil and with an additional
load factor of 1.2, a minimum dia of 300mm and meet all the requirements of clauses 6.3.2
and 6.1.3.
5)
The lateral pressure on the leading face of the cap in the rock, as well as the friction on the
two side faces in the rock shall be 135kPa for soft rock and 300kPa for hard rock or 80% of
the permissible value determined from appropriate tests.
6)
Piles shall be tested as to clauses 6.7
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c)
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Multiple cast-in-situ piles
Foundations utilising multiple cast-in-situ piles of a minimum diameter of 300 mm, will be
considered by the Design Engineer if the following criteria are met:
d)
1)
A minimum of two vertical piles per leg are used, connected to the structural steelwork by
means of a reinforced concrete pile cap. Raked piles will be accepted in accordance with
clause 6.3.2 upon submission of all method statements and review of calculations and
drawings by Design Engineer.
2)
The piles and pile cap shall be designed for the maximum combinations of uplift and
compression loadings, and the total horizontal base shear forces associated with the
vertical loadings, including leg shear. Lateral load design bending moments shall be
calculated taking into account possible plastic soil deformation.
3)
The piles shall be reinforced for their entire lengths in order to resist the applied axial and
bending forces and sufficient reinforcing hoops shall be provided to support the vertical
reinforcing. The reinforcement shall extend into the pile cap sufficiently, and shall be
suitably anchored to ensure full transfer of forces from pile cap to pile. The pile cap shall
be reinforced to withstand the shear and bending forces applied by the structural steelwork.
4)
The minimum pile centre to centre spacing shall be three times the pile diameters.
Allowance shall be made for the smaller group effect when two or more piles, with a centre
to centre spacing of less than three pile diameters, are used in a group.
Rock anchors
Foundations utilising grouted rock anchors will be considered by the Design Engineer if the
following criteria are met:
1)
A minimum of four vertical rock anchors shall be used and connected to the structural
steelwork by means of a reinforced concrete pile/anchor cap. Inclined rock anchors shall
not be used without the Design Engineer’s prior acceptance.
2)
Rock anchor foundations shall be designed to anchor and accommodate rock up to 2.5m
depth below the ground surface with the tower leg/stub in a reinforced column similar to the
pad and column foundation.
3)
The rock anchors shall be designed to resist the full axial forces imparted by the maximum
combinations of uplift and compression loadings, and additional axial loads due to the total
horizontal base shear. The design shall incorporate a 650 mm maximum projection of the
foundation above ground level. The rock anchors shall not carry any horizontal shear load.
4)
The pile/anchor cap shall be designed to resist the total horizontal base shear. No
horizontal shear resistance shall be assumed for re-compacted excavated soil. The base
of the pile cap shall be extended to a minimum of 150 mm below the top of sound rock over
its full area irrespective of horizontal shear resistance requirements.
5)
The rock anchors shall be reinforced for their entire length in order to resist the applied
axial forces and the reinforcing extends into the pile cap sufficiently and is suitably
anchored to ensure full transfer of forces from pile/anchor cap to anchor(s). The cap shall
be reinforced to withstand the shear and bending forces applied by the structural steelwork.
The rock anchor reinforcing steel shall be a minimum diameter of 25mm and de-bonded,
by a method accepted by the Design Engineer for a length of 100 mm above and 300 mm
below the pile cap base.
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6)
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Rock anchors shall only be installed in hard rock, or sound competent soft rock. Proposals
to utilise rock anchors in materials such as shale etc. shall be specifically accepted by the
Design Engineer after a pile/anchor test, as described in clause 6.7, has been conducted.
An additional test to verify that the pile cap will resist the entire horizontal base shear may
also be required if so specified by the Design Engineer. The lateral pressure on the
leading face of the cap in the rock, as well as the friction on the two side faces in the rock
shall be 135kPa for soft rock and 300kPa for hard rock or 80% of the permissible value
determined from appropriate tests.
7)
The use of grout mixes, including proprietary mixes, shall be accepted by the Design
Engineer prior to the use of such. Documented evidence of use in other similar
applications, which have been accepted by a recognised authority, shall be submitted as
proof of suitability. In-situ rock anchor testing shall be carried out as specified in clause
6.6.1.
8)
Rock anchors with diameter smaller than 85mm shall only be installed in sound competent
rock where the holes have uniform diameters, straight sides and special grouts are used
(epoxy or similar with 50MPa minimum strength) as approved by the Design Engineer. Insitu rock anchor testing shall be carried out as specified in clause 6.7.
9)
Allowance shall be made for all possible group effects when two or more anchors, are used
in a group. For 40 mm anchors the centre to centre spacing shall be greater than or equal
to 500 mm and for 100 mm anchors the centre to centre spacing shall be greater than or
equal to 650 mm.
10)
Rock anchors shall be tested as to clauses 6.7
11)
Inclined rock anchors shall have galvanized anchor bars. To ensure complete compaction
of the grout/epoxy, it shall be pumped into the holes from the bottom upwards.
6.3
Guy anchors
6.3.1
General
a)
The Contractor shall be responsible for the type of anchors chosen and the design thereof.
Anchors requiring or relying on post tensioning will not be allowed. The design of guy anchors
shall include a minimum of 105 micron thick hot dip galvanising on steel link plates (type
S355JR steel) with the following minimum cross sectional dimensions for the respective voltages
1)
For 275/400kV power lines – link plate minimum cross sectional dimensions to be 120 mm
width x 25 mm thick.
2)
For 765kV power lines- the link plate minimum cross sectional dimensions to be 130 mm
width x 30 mm thick.
3)
All link plates width to be orientated with the width in a vertically plane (include sketch
below). In addition the U-bolts (both U legs in the same angled level plane) should be
covered adequately to prevent cattle from being caught.
4)
All link plates must be painted with a bitumastic paint 500mm below ground level and
500mm above ground level.
b)
Unless otherwise specified, the anchors shall be capable of resisting a tension as stated in the Line
Specification Contract documents, and also satisfy the test requirements as described in clause 6.7
below.
c)
Owing to the dissimilarities in anchor performance and conventional foundation performance in
uplift conditions, the Contractor shall exercise extreme caution in utilising soil / rock parameters
stated in clause 6.1.2 for the design of anchors. Full-scale load tests shall be utilised to determine
actual soil holding capacities of anchor designs for 5% of installed anchors. The depth of dead
man type anchors shall be determined with respect to the dead man and not the attachment point.
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d)
e)
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All steel link plates extending below the ground level, shall be encased in concrete (minimum grade
25MPa/13 mm coarse aggregate) using a 300 mm diameter minimum HDPE (High Density Poly
Ethylene) pipe as permanent formwork. The encasement shall be proud of the ground by a
minimum of 250 mm with an appropriately smooth trowelled watershed top surface.
Steelwork of the guy anchors shall be so selected by the Contractor to have the following minimum
properties:
All ferrous material representing the final product shall have a minimum Charpy V-notch impact
energy of 27 joules at 20°C.
Ductility of all ferrous material at room temperature shall be sufficient to provide a minimum
elongation in a gauge length of 5.65√So, including the fracture, of 18 percent. (So= cross section
area of the test specimen). Grade S355JR steel which, when tested, meets the above
requirements may be accepted at the Design Engineer’s discretion.
f)
Guy anchors shall be installed in such a manner that the legs of the U-bolt are in the vertical plane.
The design of the hole to fit the U-bolt must be adequately chamfered to cater for the complete
profile of the U-bolt. Hole edge chamfering alone is not adequate for the thickness of the link
plates used. See also 7.3.
g)
The total anchor assembly (link plus reinforcing steel) for single in line drilled anchors less than 250
mm in diameter shall be hot dip galvanised. The entire link assembly for single in line drilled
anchors greater or equal to 250 mm in diameter shall be hot dip galvanised. All hot dip galvanizing
shall be in accordance with SANS 121.
h)
The link plate shall be firmly keyed into the concrete by means of bolted-on cleats. The cleats
bearing pressure on the concrete shall not exceed 10MPa. When calculating the number and size
of cleats required, the number of cleat bolts required shall be calculated in accordance with the bolt
grade ultimate strength.
i)
Anchors blocks (deadman) shall have a minimum thickness and width (i.e. cross section) of
750mm.
6.3.2
Single inclined drilled pile anchors
a)
Inclined drilled anchors shall be design with of maximum tension capacity of 0.7 (as per 6.17,
SANS 10280 Table2) that is 1.43 times the ultimate applied load.
For single in line drilled micro pile and pile anchors, the following top depths from the surface shall
be ignored for anchorage purposes:
1)
for rock anchors in hard rock ignore the top 350 mm of the rock profile
2)
for rock anchors in soft rock ignore the top 650 mm of the soil profile
3)
for soil anchors ignore the top 1200 mm of the soil profile
b)
Inclined Rock anchors smaller than 150mm dia shall have galvanized reinforcing bars with a
minimum dia of 25 mm.
c)
Inclined piles in soil shall be a minimum dia of 300mm
d)
The distance between the highest point of the foundation and the ground surface shall be a
minimum of 250 mm and a maximum of 600 mm.
e)
The concrete grout shall be pumped into pile hole from the bottom upwards by means of a tremie
pipe extending down the full length of the pile hole. A poker vibrator shall be placed in the bottom of
the pile hole prior to any concrete placement and gradually lifted together with the concrete pour.
f)
Proof load testing (full scale) is to be done on a minimum of 10% of all in line drilled/inclined pile
anchors which will be randomly selected or where required by the Design Engineer and Eskom
Site Representative.
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6.3.3
Foundations for concrete or steel poles
a)
General
b)
6.3.4
Unique Identifier: 240-47172520
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1)
The Contractor shall be responsible for the design of all foundations for pole structures.
2)
The foundations shall be designed to withstand the maximum combinations of induced
factored moment, compression and torsion loads. The dead weight of the pole shall be
included at unity factor of safety.
3)
All foundation designs are to be accepted by the Design Engineer prior to the utilisation of
any such design for pole installation purposes.
Testing
1)
Prior to the construction of any pole foundations, the Contractor shall, if requested by the
Project Manager / Design Engineer install in each general soil type encountered and at
any additional locations, test poles for the purpose of carrying out full scale load tests to
determine the moment carrying capacity in each soil type.
2)
The test pole and foundation shall not be part of a final foundation.
3)
The Contractor shall prepare the test procedure, and supply all equipment and personnel to
perform the tests. The tests shall be conducted in the presence of the Eskom Site
Representative.
4)
The pole foundation shall be capable of withstanding the full design moment (ultimate
moment) for 5 minutes with a displacement at ground level of less than 5 mm.
5)
The test shall be continued to failure of either the pole or the foundation i.e. either a creep
rate greater than or equal to 2 mm per minute of the pole measured at ground level, or a
pole tip deflection greater than or equal to 10° with respect to the original point of intersection
of the pole with the ground.
6)
Upon completion of the test, the pole shall be either removed or demolished to at least 600
mm below ground level and properly disposed of and ground to be rehabilitated.
Special foundation designs
If the geotechnical investigation reveals any other severe or extreme conditions applicable to the
construction of the foundations, special foundation designs may be required. For example these special
designs can be applied for the construction of power lines over undermined areas, on severe slopes or
foundations subjected to water scour or marshy areas. These foundation designs shall be subject to the
acceptance by the Design Engineer.
6.4
Concrete and grouts
6.4.1
General
a)
Concrete mix designs shall be proportioned to obtain a specified strength of 25MPa, and a target
strength of 35MPa, with a minimum cement: water ratio of 1.8 : 1 as per SANS 10100-2. No more
than one individual 28 day concrete test cube result from the 4 cube batch shall fall more than
3MPa below the minimum specified strength. For moderate to severe conditions the mix design
3
shall comply with SANS10100-2 where the minimum cement content shall be 340 kg/m CEM II or
CEM I cement with extenders.
b)
Grout mix designs for rock anchors shall be proportioned to attain a specified strength of 35MPa at
28 days with any expansive additives included. The use of epoxy grouts will only be allowed after
acceptance by the Design Engineer.
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OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
c)
30 of 104
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Water shall be of a potable quality, clean and free from all earthy, vegetable or organic matter,
acids or alkaline substances in solution or suspension.
6.4.2
Cement types
a)
Concrete shall be batched utilising common cement types manufactured in accordance with SANS
ENV 197-1.
b)
The minimum cement class used in concrete will be Class 32.5.
c)
CEM I - Class 52.5 and accelerating admixtures shall not normally be utilised for concrete batching.
Their use will only be considered by the Design Engineer in unusual circumstances, in order to
expedite tower erection to facilitate conductor stringing. The Contractor shall make test cubes and
arrange for their testing, to confirm the concrete strength, and obtain acceptance from the Eskom
Site Representative before proceeding with other activities.
d)
Site blending will be acceptable provided the following criteria are met:
1)
Proportion of Portland cement and Extenders are within industry norms (i.e. maximum 50%
replacement for slag and maximum 25% replacement for Fly Ash).
2)
The cementitious materials shall be weighted into the mix with an accuracy of 2% or better.
In special cases the Design Engineer may require that the replacement value indicated in
i) above be increased.
e)
The cement utilised for grout mixes shall be of a “non-shrink” type. Any shrinkage-compensating
admixture shall only be used with the Design Engineer’s acceptance.
f)
Cement extenders used shall comply with the following SANS specifications:
1)
Ground granulated blast furnace slag (slag) – SANS 1491-1
2)
Fly Ash (FA) SANS 1491-2
3)
Condense silica fume
SANS 1491-3
g)
Lesser durable concrete mixes (without blenders) can be designed if the contractor proof that no
severe conditions exist by analysing the soil along the line for Chlorites and Sulphates and also
testing the concrete aggregate for ASR proneness. These laboratory reports (with results) and
tested mix designs and must be submitted to Eskom for approval.
6.4.3
Aggregates
a)
Fine and coarse aggregate shall be obtained from sources accepted by the Design Engineer and
shall be assessed in accordance with SANS 1083.
b)
Fine aggregate shall be natural sand or other accepted inert material with similar characteristics,
composed of clean, hard, strong, durable, uncoated particles. Fine aggregates shall be free from
deleterious amounts of soft, flaky or porous particles, loam, soft shale, clay lumps or organic
material.
c)
Fine aggregates shall be selected from local sources to provide a reasonably uniform grading of
the various size fractions. Fine aggregates having a large deficiency or excess of any size fraction,
shall be avoided to the extent practicable.
d)
Coarse aggregate shall consist of crushed stone, gravel or other accepted inert material of similar
characteristics having hard, strong, durable, uncoated pieces free from deleterious substances.
e)
Coarse aggregates up to 26.5 mm nominal size may be single-sized stone. Coarse aggregates up
to 40 mm nominal size shall be blended consisting of two parts by volume of single-sized 40 mm
stone to one part by volume of single-sized 20 mm stone. The content of fine material (less than
4,75mm) in coarse aggregate shall be less than 10% by mass.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
f)
g)
Unique Identifier: 240-47172520
Revision:
5.2
31 of 104
Page:
The bulk void content of fine or coarse aggregate shall not exceed 48%. Aggregate shall not
contain any materials that are reactive with any alkali in the aggregate itself or in the cement, the
mixing water or in water in contact with the finished concrete or grout in amounts sufficient to cause
excessive localised or general expansion of the concrete or grout.
Notwithstanding the limits on chlorides as per SANS 1083 (BS 882), the acid soluble chloride as
NaCl level in aggregate as a percentage by mass shall not exceed the limits given in the following
table:
CONCRETE TYPE
COARSE
AGGREGATE
FINE
AGGREGATE
Reinforced with OPC
(Ordinary Portland cement)
0.05%
0.10%
Reinforced with SRPC
(Sulphate resisting Portland
cement)
0.02%
0.05%
NOTE: These limits shall be subject to the overall limit for the concrete as mixed.
h)
The maximum nominal aggregate size for concrete batching shall be as follows:

unreinforced concrete:
37.5 mm

reinforced concrete excluding piles:
26.5 mm

piles:
19 mm

grout:
10 mm
6.4.4
Workability
a)
Concrete mix designs and batching shall be conducted in a manner to achieve adequate
workability, to ensure that the concrete will be dense, without voids or honeycombing.
b)
The design mix workability of the concrete, as determined by the “Slump Test”, shall meet the
following requirements by application:
1)
unreinforced concrete:
25 mm – 75 mm
2)
reinforced concrete for conventional foundations and pile caps:
65 mm – 100mm
3)
reinforced concrete for cast in-situ piles:
100 mm – 150 mm
4)
reinforced concrete for cast in-situ inclined piles/anchors:
150 mm – 200 mm
c)
Adjusting of the slump on site shall only be done by adding the mix design admixture amount
strictly to manufacturer’s instructions and mix proportions.
d)
The consistency of grout mixtures shall be proportioned so that the mixture is pourable. The fine
aggregate to cement ratio shall not exceed 3:1 irrespective of workability.
e)
Any admixtures to the concrete proposed by the Contractor shall be subject to the Design
Engineer’s acceptance.
6.4.5
Reinforcing steel
a)
All main reinforcing steel shall conform to SANS 920 Type C, Class 2, and Grade II hot rolled
deformed bars with a minimum yield stress of 450MPa. The minimum bar size utilised shall be 10
mm.
b)
All secondary reinforcing for stirrups, hoops and spirals, shall as a minimum conform to SANS 920
Type "A" hot rolled bars of plain cross-section of mild steel with a minimum yield stress of 250MPa.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
c)
6.5
Unique Identifier: 240-47172520
Revision:
5.2
32 of 104
Page:
At the Contractor's option or as required by design, Type B or Type C reinforcing steel may be
utilised. The minimum bar sizes utilised shall be at least 0.25 times the largest main reinforcing
bar, or 0.01 times the average of the cross-sectional dimensions of the concrete with a minimum
diameter of 6 mm allowed.
Construction
The first installation of each foundation per soil type shall be witnessed by the Design Engineer.
Two Holding points are required during the foundation construction before proceeding with the next
construction phase.
First holding point; No construction may start without the approval of the foundation -soil nominations by the
Design Engineer.
Second holding point; No concrete may be placed before the inspection of the excavation, reinforcing,
stubs or link positions, have all been checked by the Eskom Site Representative.
The Eskom Site Representative shall take photos at the 2nd holding point before concrete placing and then
during the backfilling. These photos shall be submitted on a regular basis to the Eskom Project Manager
and the Eskom Design Engineer.
6.5.1
Excavation
a)
At each tower or pole position, the Contractor shall excavate, construct the appropriate foundation
and backfill the excavation as required. Excavation in this instance shall be the removal of soil/rock
by any accepted means for the purpose of constructing a particular foundation system, including
conventional pad and pier type foundations, spread footings, piles, anchors, etc.
b)
No excavation work, other than for soil investigation, shall be commenced on a section of line until
the following conditions have been met:
1)
The Contractor has submitted a schedule of tower leg ground levels and proposed leg
extension lengths to the Design Engineer.
2)
The Contractor has submitted the proposed foundation and soil type nomination
schedules to the Design Engineer.
3)
If drilled cast-in-situ piles or rock anchors are proposed, soil samples and pile/anchor tests
have been conducted, if so instructed by the Design Engineer.
4)
The excavated top soil shall be kept separate from the subsoil
c)
Excavations shall be made to the full foundation dimensions required, and shall be finished to the
prescribed lines and levels. The bottom or sides of excavations upon or against which concrete is
to be poured shall be undisturbed for type 1 and type 2 soils. If, at any point in excavation, the
natural material is disturbed or loosened or over excavated, the over-excavations shall be
backfilled with 10MPa concrete, including the application of a blinding layer at the base of
foundations where these eventualities are likely to occur during the construction process. Soil
backfilling will not be accepted.
d)
When the material at foundation depth is found to be partly rock or incompressible material, and
partly a soil or material that is compressible, all compressible material shall be removed for an
additional depth of 200 mm and backfilled with 10MPa concrete “reimbursable as per to the bill of
quantities”.
e)
The excavations shall be protected so as to maintain a clean subgrade until the foundation is
placed. Any water, sand, mud, silt or other objectionable material which may accumulate in the
excavation including the bottom of pile or anchor holes, shall be removed prior to concrete
placement.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
f)
Unique Identifier: 240-47172520
Revision:
5.2
33 of 104
Page:
Excavations for cast-in-situ concrete, including pile caps cast against earth, shall be concreted
within seventy-two hours after beginning the excavations. In addition to this general requirement,
pile and/or anchor holes that are not adequately protected against the elements, must be corrected
and be acceptable to the Eskom Site Representative. Soil excavations that remain un-concreted
longer than seventy-two hours shall, be required to be enlarged by 150 mm in all sides/directions.
g)
The excavations shall be kept covered or barricaded in a manner accepted by the Eskom Site
Representative to prevent injury to people or livestock. Plastic danger tape shall be added to
barricade for visual purposes. Failure to maintain proper protection of excavations may result in the
suspension of excavation work until proper protection measures have been restored.
h)
The Contractor is to notify the Eskom Site Representative upon completion of the excavation for
the foundations. No concrete is to be placed until the excavation; shuttering and reinforcing steel
have been inspected and accepted in writing by the Eskom Site Representative.
6.5.2
Backfilling
a)
After completion of foundation construction, the Contractor shall backfill each excavation with
suitable material. The Eskom Site Representative shall accept the materials used for backfill, the
amounts used and the manner of depositing and compaction of the materials.
b)
The material to be utilised for compacted backfill shall be moistened to OMC (optimum moisture
content ±10%), and deposited in horizontal layers, having a thickness of not more than 300 mm
before being compacted. In backfilling, the pad of the foundation shall be covered, first with a 200
mm layer of well-graded material containing no pieces larger than 20 mm, before any coarse
material is deposited.
c)
The backfill material to be compacted shall contain no stones more than 150 mm in diameter, and
be free from organic material such as trees, brush, scraps, etc.
d)
The distribution of material shall be such that the compacted material will be homogenous to
secure the best practicable degree of compaction, impermeability and stability.
e)
Prior to and during compaction operations, the backfill material shall have the optimum moisture
content required for the purpose of compaction, impermeability and stability.
f)
The material shall be mechanically compacted to a minimum of 90% of the dry density of the
undisturbed material.
g)
The surface of the backfill around the foundation shall be carried to such an elevation that water
will not accumulate on top of the backfilled area.
h)
Material removed from the excavation, which is either not suitable or not required for backfill, shall
be spread evenly over or adjacent to the site, or be disposed of as directed by the Eskom Site
Representative. Spreading of subsoil in agricultural areas will not be allowed. Excavated soil
suitable for backfill will be returned to the excavation by backfilling with the subsoil first and the top
soil last.
i)
Where the excavated material is considered to be unsuitable for backfill, such as a material with
high clay content or a sandy material with little variation in particle size, the Contractor shall
propose a suitable method of soil improvement for consideration and acceptance by the Eskom
Design Engineer prior to being implemented. The properties of the soil may be improved by the
addition of stabilising agents such as Portland cement in the case of sandy soils and slaked lime in
the case of clay soils. Backfill material stabilised in this way shall be mixed in the ratio of cement or
lime: soil of 1:10. This material shall be properly mixed, moistened, placed and compacted in the
same manner as other excavated material.
j)
Where the material is found to be a matrix of boulders and soil, the removable boulders shall be
removed “reimbursable as per to the “bill of quantities.” as also the extra-over for the imported
backfill.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
6.6
Concrete foundations
6.6.1
Supply of materials
Unique Identifier: 240-47172520
Revision:
5.2
Page:
34 of 104
The Contractor shall supply all concrete and concrete materials required for construction, including
aggregates, cement, water, admixtures (if any), shuttering, reinforcing steel, all embedded steel components
and materials for curing concrete.
6.6.2
Prior to the concrete mix acceptance and placement
a)
Well in advance of construction, the Contractor shall select the location of aggregate sources for
concrete, and obtain representative samples of all aggregates. A representative sample shall
consist of a blend of twelve separate samples from each aggregate stockpile. The representative
samples shall be divided into two portions, one set of which shall be examined and accepted by the
Eskom Site Representative and maintained on site during concreting operations. The second set
which shall be delivered by the Contractor to the Portland Cement Institute, or other laboratory
accepted by the Design Engineer, for examination of suitability of the aggregate in accordance
with SANS 1083 and preparation of concrete trial mix design in accordance with the requirements
of clause 6.6.6. Prior to any concrete placement the Contractor shall submit the trial mix designs
and results of seven and twenty-eight day test cube strengths to the Design Engineer for
acceptance.
b)
Contractor shall obtain, from the ready-mix supplier, aggregate test reports and mix designs that
satisfy the requirements of clause 6.4 and test cube strength reports of all mix designs and submit
it to the Design Engineer for acceptance prior to placement of any concrete. A ready-mix
concrete supplier that does not have SANS 979 recognition shall only be used with the Design
Engineer’s acceptance, and thereafter only after satisfying the above requirements.
6.6.3
Tolerances for concrete construction
The intent of this paragraph is to establish tolerances that are consistent with construction practice, and the
effect that permissible deviations will have upon the structural action or operational function of the structure.
Where tolerances are not stated for any individual structure or feature, permissible deviations will be
interpreted in conformity with the provisions of this paragraph. The Contractor shall be responsible for
setting out and maintaining concrete excavations, shuttering and structural steelwork within the tolerance
limits so as to ensure completed work within the specified tolerances. Concrete work, that exceeds the
tolerance limits specified shall be remedied, or removed and replaced.
a)
b)
Variation in structure location

Transverse to centre-line: less than 50 mm

Longitudinal displacement: less than 300 mm
Variation in relative vertical elevation of structural steelwork (one leg to another)

c)
d)
Variation in horizontal distance between structural steelwork from that computed

Adjacent legs:
less than 5 mm

Diagonal legs:
less than 7 mm
Rotation - maximum deviation of transverse axis of structure from bisector of interior line angle

e)
less than 5mm
less than 0º 30’
Elevation - variation of tower base from centre-line peg

minus 150 mm

plus 350 mm
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
f)
g)
i)
Revision:
5.2
Page:
35 of 104
Height of concrete foundations above ground level

min. 250 mm (±10 mm)

max. – as per design
Variation in relative placement of foundation components from those indicated on drawings,
including piles, shuttering, and structural steelwork

h)
Unique Identifier: 240-47172520
less than 50 mm
Tolerances for placing reinforcing steel

Variation of protective cover:

Variation from indicated spacing: 25 mm
5 mm
Tolerances for guy anchors
Guy anchors shall be installed such that the attachment point of the anchor is within 250 mm of the
correct calculated position. The attachment point shall be a minimum of 350mm and a maximum of
750mm above the ground level.
Guy anchors designed for use with anchor rods extending below ground level shall have the
anchor rod installed in line with the guy wire slope, within 1:20 (2.8 º) or such lesser tolerance as
required by design.
j)
Tolerances for pole foundations
Pole foundations shall be constructed such that the pole, and the associated foundation works are
within 50mm of the correct calculated position.
6.6.4
Workmanship
Concrete shall be proportioned, mixed, placed and finished in such a manner as to be free of honeycombing,
segregation and other defects of workmanship.
6.6.5
Formwork
a)
Formwork shall be of wood, metal or other suitable material.
b)
The formwork shall be mortar-tight and shall be designed, constructed, braced and maintained
such that the finished concrete will be true to the line and elevation, and will conform to the
required dimensions and contours. It shall be designed to withstand the pressure of concrete, the
effect of vibration as the concrete is being placed and all loads incidental to the construction
operations without distortion or displacement.
c)
Where the bottom of the formwork is inaccessible, provision shall be made for cleaning out
extraneous material immediately before placing the concrete.
d)
All exposed corners of the concrete shall be chamfered approximately 20 mm. A suitable nosing
tool may be used for horizontal chamfers only if approved by the Eskom Site Representative. All
formwork dimensions shall be checked, and if necessary, corrected before any concrete is placed.
e)
All formwork shall be treated with a formwork-release agent accepted by the Eskom Site
Representative before concrete is placed. Any release agent, which will adhere to, discolour or be
deleterious to the concrete, shall not be used.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
6.6.6
Unique Identifier: 240-47172520
Revision:
5.2
Page:
36 of 104
Concrete and grout mixing and testing
The concrete mix shall consist of ordinary Portland cement, fine aggregate, coarse aggregate and water
proportioned in accordance with the mix design accepted by Design Engineer. Adjustments in these
proportions may be directed at any time when found necessary as a result of field tests of the concrete. No
change in mix proportions shall be made unless instructed by the Eskom Design Engineer. As an
alternative to the use of ordinary Portland cement, the Eskom Design Engineer may consider the use of
other approved types of cement or blends thereof.
a)
No change in the source, character or grading of materials shall be made without written notice to
the Eskom Site Representative and without a revised mix design being prepared and accepted by
the Eskom Design Engineer prior to use of these materials.
b)
During the concrete operations, the concrete mixture shall be tested for each batch by the
Contractor to determine the slump of the fresh concrete in accordance with SANS Method 5862.
Records of slump tests shall be supplied to the Eskom Site Representative on a daily basis.
c)
Test cubes shall be prepared, in accordance with SANS Method 5863 at the initiation of the
concrete placement of each truck/batch for the first three batches and twice every day that
concrete is batched thereafter or for every 20 cubic meters where this amount is exceeded. Test
cubes shall only be made out of a concrete batch at the point of discharge in actual use. Unless a
concession is granted by the Employer, the Contractor shall install suitable on-site laboratory
facilities for the storage and crushing of test cubes. The crushing equipment shall be appropriately
calibrated (with traceability to SANS5863) and accompanied by up-to date certification available for
inspection at all times. The Eskom Site Representative shall witness all cube crushing tests.
1)
The first set of test cubes shall consist of five cubes, thereafter each set shall consist of
four cubes minimum.
2)
One to be crushed at seven days and three to be crushed at twenty eight days. The written
results of the test cube strength tests shall be immediately forwarded to the Supervisor
upon receipt.
3)
The 5 cube shall be an accelerated 24 hour curing test to be tested, for every first batch of
a mix design or new supplier and randomly thereafter as advised by the Eskom Site
Representative (procedure as per line project appendix).
4)
The 5 cube must be cured in water at a temperature of 55ºC for 20 hours, then cooled in
water at a temperature of 20ºC for 2 hours and tested for the compressive strength.
5)
Additional test cubes shall be prepared and crushed as directed by the Eskom Site
Representative where the concrete strengths are in question.
6)
Grout cubes shall be taken for every tower with grouted anchor foundations and the cubes
shall be tested to the same procedures as with the concrete cubes.
th
th
d)
All cement shall be batched by mass. Cement shall be weighed to within 2% accuracy.
e)
Aggregates may be batched by mass or by volume, provided that volumetric batching equipment is
calibrated at the start of concrete operations by weighing a typical discharge. The quantities of
aggregate batched shall be volume batched within 2% accuracy. Adjustments of fine aggregate
volumes due to "bulking" shall be accounted for in batching as to SANS 0100-2.
f)
The amount of moisture in the aggregates shall be determined on a daily basis by a method
accepted by the Eskom Site Representative, and the water requirements as per the mix design
altered accordingly.
g)
Water quantities, including aggregate moisture allowances, shall be determined within 2%
accuracy. The use of water meters for dispensing water shall be subject to the Eskom Site
Representative’s acceptance.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
37 of 104
6.6.7
Mixing of concrete
a)
Concrete shall be mixed sufficiently to ensure that the various sizes of aggregate are uniformly
distributed throughout the mass, and each aggregate particle is adequately coated with cement
paste of uniform consistency. Concrete delivered to site that lacks homogeneity should be mixed
for a longer time or discarded, as directed by the Eskom Site Representative.
b)
For mixers of one cubic metre or less, the mixing time shall not be less than ninety seconds after all
ingredients have been discharged into the mixer. For mixers of larger capacities, minimum mixing
times shall be increased by fifteen seconds for each additional half cubic metre of mixer capacity,
or fraction thereof.
c)
Concrete delivered to the job site shall be mixed en-route. Mixing shall be rigorously controlled for
agitating time, mixing time and overall time upon arrival at the foundation construction site.
Concrete discharge shall be completed within one and one-half hours after introduction of the water
to the cement and aggregate.
d)
In exceptional cases only with the acceptance of the Eskom Design Engineer, may the
Contractor at his own risk add water to a concrete mix at the point of delivery. The maximum
amount of water that may be added on site is three litres per cubic metre of concrete. At no time
shall the cement / water ratio be less than 1.8.
e)
Non-shrink grout shall be mixed in a suitable mechanical grout mixer/pump accepted by the
Eskom Site Representative.
6.6.8
Placement of reinforcing steel
a)
The Contractor shall install all the reinforcing steel required for foundations. Reinforcing steel
shall be fabricated and bent in strict accordance with the drawings and SANS 82.
b)
Reinforcing steel, before being positioned, shall be thoroughly cleaned of mill scale and any
coatings that will destroy or reduce bond.
c)
Reinforcing steel shall be accurately positioned and secured against displacement during placing
and vibrating of concrete. Reinforcing bars shall be tied at all intersections with no less than No.18
gauge annealed wire. Reinforcing bars shall be overlapped forty-five diameters at all splices,
unless shown otherwise on the drawings. Reinforcing steel shall be provided and placed as
detailed on the foundation drawings. Unless otherwise shown on the drawings, the minimum cover
to the main reinforcing bars in a pile, a pile cap, or chimney shall be 50 mm and 75 mm for the
sides, and bottom of the slab or anchor. Use of suitable accepted spacers or supports shall be
made, to ensure that the minimum concrete cover to the reinforcement is maintained during the
placement of concrete. Where cover blocks are used to support the lower layers of reinforcing,
these shall be at least 75 mm thick to make allowance for the uneven ground surface on which the
reinforcing cage rests.
6.6.9
Placement of embedded items
a)
The Contractor shall install all required embedded items shown on the drawings, prior to placing
(pouring) of concrete. Structural steelwork or holding down bolts shall be accurately positioned and
securely held in place during the placement (pouring) of concrete. The minimum cover to all
embedded items, but excluding angle stubs, shall be 150 mm. The minimum cover to angle stubs
and cleats shall be 75 mm unless otherwise shown on the drawings.
b)
Angle stubs may be supported on the bottom of excavations by either precast concrete slabs set at
the correct level by placing suitable grout or concrete underneath it, or on a previously placed
blinding layer of 10MPa concrete installed up to the correct level. The precast slab shall be square
in plan with a side dimension of 300 mm, and a depth of 75 mm, and shall be constructed using
reinforced concrete with a minimum characteristic strength of 25MPa. The placing of loose rubble,
stones, bricks, etc. under the precast slab will not be acceptable.
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THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
c)
38 of 104
Page:
Structural steelwork or anchor bolts shall be embedded such that the top of the concrete of the
foundation correctly coincides with the designed level.
d)
Earthing requirements are to be as per the latest revision of standard “TST41-321 Earthing of
Transmission Line Towers” and the instructions provided in Annex D.
e)
Notwithstanding the above mentioned standard, if additional earthing buried in soil is to be applied
in order to achieve the required tower footing resistance, the material used, must be copper clad
steel with a service lifespan in excess of 50 years and with a low scrap value.
6.6.10 Placement of concrete
a)
No concrete for foundations shall be placed (poured) until each foundation has been inspected and
accepted by the Eskom Site Representative. The foundation at the time of this inspection shall
be ready for concrete placement (pouring) including reinforcing steel, embedded items and any
necessary formwork.
b)
All surfaces of the foundation upon or against which concrete is to be placed shall be free from
mud and/or loose or disturbed material. A blinding layer of 10MPa between 50 mm to 100 mm is to
be installed on all bottom surfaces of type 3 and type 4 foundations and where where warranted,
and approved by the Eskom Site Representative.
c)
The surfaces of dry absorptive materials, against which concrete is to be placed, shall be
moistened prior to the placing of concrete to prevent excessive moisture being withdrawn from the
fresh concrete.
d)
At least two suitable concrete poker vibrators shall be ready for operation at the site prior to
placement of concrete.
e)
Freshly mixed concrete shall be handled, transported and deposited in such a manner as to
prevent segregation or loss of material. When discharging concrete by chute, the slope of the
chute shall be uniform throughout its length and shall not be flatter than 1 in 3 or steeper than 1 in
2. Baffles shall be provided at the end of the chute to ensure a vertical discharge of the concrete
into the foundation. The maximum free discharge height shall be three metres, and for heights in
excess of this, a tremie pipe shall be used.
f)
Placement (pouring) of concrete shall not commence when the air temperature is below 5°C.
0
Where temperatures falls to 0 C, insulating covering must be placed on the concrete surfaces for
at least 2 days to cover and insulate the concrete from the cold.
g)
The temperature of the concrete mixture immediately before placement (pouring) shall not exceed
32°C. Concrete exceeding this temperature shall be discarded. During hot weather concreting
operations, the Contractor shall take and record the temperature of each batch of concrete.
h)
No concrete shall be placed which has taken its initial set, regardless of whether the specified one
and one-half hour period has elapsed or not. If a setting retarder, accepted by the Eskom Design
Engineer, has been used, the one and one-half hour period may be exceeded provided the
concrete has not taken its initial set. The Contractor shall dispose of waste concrete in a place
acceptable to the Eskom Site Representative.
i)
Concrete shall be placed under water, with a suitable watertight tremie, accepted by the Eskom
Site Representative, of sufficient length to reach the bottom of the excavation. The tremie shall
be free of water when filled with concrete to the bottom of the excavation. The tremie shall be kept
full of concrete during the entire concrete placing operation. The discharge end of the tremie shall
not be lifted out of the freshly placed mass of concrete until the concrete placement has been
completed.
j)
Concrete shall be thoroughly settled and compacted into a dense homogeneous mass throughout
the whole depth of each layer being consolidated, using internal vibrators. Excessive vibration,
causing segregation, is to be avoided. Concrete vibrator penetrations shall be at ± 400 mm
spacing and shall not be used to move concrete.
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k)
Unique Identifier: 240-47172520
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The concrete in cast-in-situ piles shall be vibrated from the bottom upwards.
l)
Unless authorised by the Eskom Site Representative, the Contractor shall not place concrete,
unless the Eskom Site Representative is present during the entire placement operation.
m)
When alternative foundations consisting of multiple cast-in-situ piles and pile caps are utilised, the
Contractor shall at approximately one tower in twenty, open up on two sides of the completed
foundation of one leg, the pile cap and top 500 mm of the piles, if so instructed by the Eskom Site
Representative. If the foundation is rejected for any reason, the Contractor shall open up as
many additional foundations as determined by the Eskom Site Representative who will refer it to
the Eskom Design Engineer, as is necessary to fully assess the problem. Foundations accepted
are to be backfilled using 10MPa concrete up to a level at least 150 mm above the base of the pile
cap.
n)
Concrete in all drilled foundations utilising piles, shall be inspected immediately prior to concrete
placement using a suitable high powered torch and measuring tape. The inspection is required to
determine:
1)
That no soil has fallen into the drilled hole such that either the design length or the design
diameter of the pile has been affected, and
2)
That no material from the hole sides has become dislodged and has fallen against
reinforcing. No concrete will be allowed to fall directly against the hole sides during
placement. A poker vibrator shall be placed in the bottom of the pile hole prior to any
concrete placement and gradually lifted with the concrete pour. With inclined piles the
concrete is to be placed by means of a tremie pipe which extends down the full length of
the pile. The tremie pipe, together with the poker vibrator can then be gradually lifted
together with the pour.
6.6.11 Construction joints
a)
In general, foundations shall be constructed monolithically. Construction joints are to be avoided
as far as possible. If construction joints cannot be avoided and are accepted by the Eskom Site
Representative, the Contractor may be permitted to make a construction joint if the following
criteria are met:
1)
The concrete is reinforced and the reinforcing steel will develop full bond strength both
sides of the construction joint. No construction joints will be allowed in unreinforced
concrete.
2)
In multiple cast-in-situ piles, the construction joint is to be 75 mm, and in rock anchors 100
mm, above either the base of the pile cap excavation or the top of blinding level. If the
piles are constructed after the excavation for the pile cap has taken place, suitable ring
shutters of the same diameter of the piles shall be used to construct the above mentioned
pile/anchor projections.
b)
No construction joints will be allowed in piles, pile caps, deadman anchors and pad slabs of pad
and pier foundations.
c)
At all construction joints, the surfaces of the previously placed and hardened concrete shall be
thoroughly cleaned of all foreign matter, and primed with a 15 mm thick layer of a wet mix of
cement and sand in equal proportions, in the presence of the Eskom Site Representative before
new concrete is placed. The grout coating shall be brushed over the concrete surface to ensure
thorough coverage, particularly between the reinforcing bars. The new concrete shall be placed
before the grout coating has taken its initial set.
6.6.12 Concrete surface finish
a)
The top surface of the foundation shall be at least a wood float finish, and shall be contoured to
shed water.
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b)
c)
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All concrete placed against shuttering shall be free from irregularities, fins, rock pockets or other
imperfections. Any rock/aggregate pockets, porous or defective concrete shall be removed to the
extent instructed by the Eskom Site Representative and repaired by filling these voids with
specialized concrete, cement mortar of a higher strength, as accepted by the Eskom Design
Engineer.
All exposed concrete sections shall be shuttered to a minimum of 250 mm below ground level.
6.6.13 Concrete curing
a)
The Contractor shall provide means of maintaining concrete in a moist condition (for curing) for at
least seven days after the placement of concrete.
b)
At the Contractor's option, concrete may be cured either by retaining shuttering in place and
applying a liquid curing compound which forms a moisture retaining membrane on un-shuttered
concrete surface, or by removing shuttering and applying a curing compound as described to all
exposed concrete surfaces. Curing compounds utilised shall be of a type accepted by the Design
Engineer. Notwithstanding these requirements, formwork shall not be removed until at least 36
hours after the final placement of the concrete against such formwork. The Contractor shall
remove formwork in such a way that shock forces and damage to the concrete are avoided.
6.6.14 Concrete cracks repair
For crack widths:
a)
All cracks less than 2mm wide and less than 30mm deep must be repaired with Eskom approved
compounds.
b)
For all larger cracks than specified in (a) above, a non-conformance must be raised and
consultation with the Eskom Design Engineer must commence.
6.6.15 Steelwork
a)
All galvanised structural steel at the steel/concrete interface shall be painted with an Eskom
approved protective paint. This protection shall extend 500 mm above and 500 mm below the top
surface level of the protruding foundation blocks. A final second coat shall be painted after
construction on the 500 mm part above the concrete and overlapping onto the concrete for ±100
mm to seal the interface.
b)
All embedded steel (i.e. Link plates and stubs) below ground line shall be galvanised and encased
in concrete. All link plates shall be encased in concrete using a minimum permanent shutter (i.e.
HDPE pipe) of 250 mm diameter minimum with at least 50 mm concrete cover. No structural steel
shall be buried or come directly in contact with the soil.
6.7
Anchor block (deadman), Pile and Rock Anchor testing
6.7.1
Design load (ultimate load) anchor test requirements
a)
General and test setup requirements
1)
Where requested by the Design Engineer the Project Manager shall, instruct the
Contractor to install in each general soil type encountered and at any additional locations,
a test cast-in-situ anchor for the purpose of verifying the ultimate anchor capacity and
concrete/soil frictional resistance values.
2)
The Contractor shall provide the equipment capable of loading the anchor and personnel
to perform the test.
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3)
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Contractor shall prepare the test procedure for the testing of deadman anchor, pile or rock
anchor for the load equal to the design load (ultimate load). The test procedure, based on
the applicable test requirements, shall be submitted to the Design Engineer for
acceptance prior to execution of the test.
4)
The design load test anchor, pile or rock anchor shall not form part of a final tower
anchors/foundation.
5)
Tests shall be conducted in the presence of the Eskom Site Representative.
6)
Anchor, pile or rock anchor foundations installed prior to acceptance by the Design
Engineer of the test results, will be subject to modification or replacement by the
Contractor should the anchor, pile or rock anchor fail the test.
7)
The test beam supports shall be placed outside the uplift influence zone of the anchor, pile
or rock anchor to be tested and the distance on either side of the anchor, pile or rock
anchor to the test beam supports shall not be less than "r".
r =( I + c) tan Ø
where:
I = depth of pile/anchor (or anchor group)
c = depth of pile/anchor cap excavation
Ø = frustum angle
8)
6.7.2
Two dial gauge micro meters shall be placed on either side of the pulling rod, in order to
eliminate errors due to rotation of the anchor, pile or rock anchor. The datum frame
supports shall also be positioned a similar distance “r” from the test pile/anchor as the test
beam supports above. The average reading of these gauges will represent the actual
creep. Should this method, for any authentic reason prove impracticable, then a suitable
approved alternative method may be used.
Block Guy Anchor (deadman) design load testing criteria
The design load shall be applied to the block anchor during the test in appropriate increments to 60%, 85%
and 100%, each for a minimum holding period of 5 minutes and finally, 100% for at least half an hour.
Successive load increments shall not be applied and the maximum test load shall be held until the rate of
movement under the acting load has stabilised at a rate of movement not exceeding 3.75 mm in 5 minutes.
The maximum test load shall also be held until the rate of movement under the applied load has stabilised at
a rate of movement not exceeding 3.75 mm in 5 minutes. The anchor will be considered to have passed
provided the total movement does not exceed 50 mm during the entire test period. The residual anchor
movement, once all load has been removed, shall be recorded at the end of the test.
6.7.3
Pile design load testing criteria
The design load shall be applied to the pile during the test in appropriate increments to 60%, 85% and 100%,
each for a minimum holding period of 5 minutes and finally, 100% for at least half an hour. Successive load
increments shall not be applied and the maximum test load shall be held until the rate of movement under
the acting load has stabilised at a rate of movement not exceeding 0.75 mm in 5 minutes. The maximum
test load shall also be held until the rate of movement under the applied load has stabilised at a rate of
movement not exceeding 0.75 mm in 5 minutes. The pile will be considered to have passed provided the
total movement does not exceed 7 mm during the entire test period. The residual pile movement, once all
load has been removed, shall be recorded at the end of the test.
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6.7.4
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Rock Anchor design load testing criteria
The design load shall be applied to the anchor during the test in appropriate increments to 50%, 75%, 90%
and 100%, each for a minimum holding period of 5 minutes and finally, 100% for at least half an hour.
Successive load increments shall not be applied and the maximum test load shall be held until the rate of
movement under the acting load has stabilised at a rate of movement not exceeding 0.25 mm in 5 minutes.
The maximum test load shall also be held until the rate of movement under the applied load has stabilised at
a rate of movement not exceeding 0.25 mm in 5 minutes. The anchor will be considered to have passed
provided the total movement does not exceed 2.5 mm during the entire test period. The residual rock anchor
movement, once all load has been removed, shall be recorded at the end of the test.
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FOUNDATION TEST CRITERIA - Design load
DESIGN LOAD
TEST
Load
holding
period
movement
Rate of
movement
DESIGN LOAD TEST
BLOCK ANCHOR (Deadman)- Soil Type 1-2
%
minutes
mm
50
5
3.75
0.75
75
5
3.75
0.75
90
5
3.75
0.75
100
30
22.5
0.75
Holding+ movement total
mm/minute
34
Total Final Allowable movement
50mm
PILE ANCHOR - FULL LOAD- Soil Type 1-2
DESIGN LOAD TEST
Load
holding period movement
Rate of
movement
%
minutes
mm
50
5
0.75
0.15
75
5
0.75
0.15
90
5
0.75
0.15
100
30
4.5
0.15
Holding+ movement total
mm/minute
6.8
Total Final movement
7mm
DESIGN LOAD TEST
ROCK ANCHOR - Soft and Hard Rock
Load
%
holding period movement
minutes
50
5
75
5
90
5
100
30
Holding+ movement total
Total Final movement
mm
0.25
0.25
0.25
1.5
Rate of
movement
mm/minute
0.05
0.05
0.05
0.05
2.3
2.5mm
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6.7.5
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Pressure grout injected anchors - test criteria
For an anchor in soils 1-3; the design load shall be applied to the anchor during the test in appropriate
increments to 50%, 75%, 90% and 100%, each for a minimum holding period of 5 minutes and finally, 100%
for at least half an hour. Successive load increments shall not be applied and the maximum test load shall
be held until the rate of movement under the acting load has stabilised at a rate of movement not exceeding
1 mm in 5 minutes. The maximum test load shall also be held until the rate of movement under the applied
load has stabilised at a rate of movement not exceeding 1 mm in 5 minutes. The anchor will be considered
to have passed provided the total movement does not exceed 10 mm during the entire test period. The
residual rock anchor movement, once all load has been removed, shall be recorded at the end of the test.
For an anchor in rock; the design load shall be applied to the anchor during the test in appropriate
increments to 50%, 75%, 90% and 100%, each for a minimum holding period of 5 minutes and finally, 100%
for at least half an hour. Successive load increments shall not be applied and the maximum test load shall
be held until the rate of movement under the acting load has stabilised at a rate of movement not exceeding
0.25 mm in 5 minutes. The maximum test load shall also be held until the rate of movement under the
applied load has stabilised at a rate of movement not exceeding 0.25 mm in 5 minutes. The anchor will be
considered to have passed provided the total movement does not exceed 3 mm during the entire test period.
The residual rock anchor movement, once all load has been removed, shall be recorded at the end of the
test.
PRESSURE GROUT INJECTED ANCHORS - TEST CRITERIA
FULL LOAD TEST
holding
period
movement
Rate of
movement
%
minutes
mm
mm/minute
50
5
1
0.2
75
5
1
0.2
90
5
1
0.2
100
30
6
0.2
Load
SINGLE ANCHOR - Soil Type 1 -3
FULL LOAD TEST
Holding+ movement total
Total Final Allowable movement
9
10mm
SINGLE ANCHOR - Soft /Hard Rock
FULL LOAD TEST
Load
holding
period
movement
Rate of
movement
%
minutes
mm
mm/minute
50
5
0.25
0.05
75
5
0.25
0.05
90
5
0.25
0.05
100
30
1.5
0.05
Holding+ movement total
Total Final Allowable movement
2.3
3mm
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6.7.6
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Proof load anchor/pile test requirements
General and test setup requirements
a)
Where instructed by the Eskom Site Representative or Design Engineer, the Contractor shall
apply a construction proof load test equal to 70% of the design loading conditions to the completed
anchor for the purpose of verifying the maximum working load capacity of the anchor.
To ensure quality assurance, anchor strength and construction integrity, the contractor shall
execute proof load tests on a minimum of 5% of the anchors installed.
b)
The Contractor shall prepare the test procedure and supply all equipment and personnel to
perform the tests. The pile/anchor test procedure, based on the following requirements, shall be
prepared by the Contractor and submitted to the Design Engineer for acceptance prior to the
execution of the tests.
c)
The Design Engineer may request that the pile/anchor foundation be tested, as a whole.
d)
Pile/Anchor proof load tests shall be conducted in the presence of the Eskom Site
Representative.
e)
Pile/Anchor foundations installed prior to acceptance by the Design Engineer of the pile/anchor
test results will be subject to modification or replacement by the Contractor should the pile/anchor
fail the test.
f)
The test beam supports shall be placed outside the uplift influence zone of the pile/anchor to be
tested and the distance from the outside of the pile/anchor (or pile/anchor group) to the test beam
support shall not be less than "r".
r = (I + c) tan Ø
where:
I = depth of pile/anchor (or pile/anchor group) with respect to the underside of the pile/anchor cap.
c = depth of pile/anchor cap excavation. and
Ø = frustum angle.
g)
Two dial gauge micro meters shall be placed on either side of the pulling rod, in order to eliminate
errors due to rotation of the test pile/anchor. The datum frame supports shall also be positioned a
similar distance from the test pile/anchor as the test beam supports above. The average reading of
these gauges will represent the actual creep. Should this method, for any authentic reason prove
impracticable, then a suitable approved alternative method may be used.
h)
The load shall be applied to the anchor in appropriate increments to 50%, 75%, 90% and 100% of
the proof test load, and then unloaded to 50% and again loaded to 100% of the proof test load,
twice, i.e. during two further cycles of loading. The Contractor shall monitor anchor/pile movement
along the guy slope or vertical slope in the case of vertical pile/anchors. Successive load
increments shall not be applied until the rate of creep is less than or equal to the measurements
listed below:
i)
1)
Block guy anchors (deadman) = 2.5 mm/minute
2)
Pile anchors = 0.1 mm/minute
3)
Rock anchors = 0.05 mm/minute.
The three cycles of loading from 50% to 100% shall each be of duration of not less than 5 minutes.
1)
A guy anchors shall be considered acceptable if the total creep from 50% to 100% load
over 3 cycles is less than 15 mm.
2)
A pile anchor shall be considered acceptable if the total creep from 50% to 100% load over
3 cycles is less than 2 mm.
3)
A rock anchor shall be considered acceptable if the total creep from 50% to 100% load
over 3 cycles is less than 1 mm.
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If the creep exceeds above criteria the anchor /pile foundation shall be modified or replaced by the
Contractor and re-tested.
j)
PROOF LOADS
PROOF LOAD
TEST
holding
period
Load
Rate of
movement
movement
PROOF LOAD TEST
BLOCK ANCHOR (Deadman)- PROOF LOAD
%
minutes
mm
mm/minute
50- 100
5
3.75
0.75
50- 100
5
3.75
0.75
50- 100
5
3.75
0.75
Holding+ movement total
11.3
Total Final Allowable movement
15mm
PROOF LOAD TEST
PILE ANCHOR - PROOF LOAD
Load
holding
period
movement
Rate of
movement
%
minutes
mm
mm/minute
50- 100
5
0.75
0.15
50- 100
5
0.75
0.15
50- 100
5
0.75
0.15
Holding+ movement total
2.3
Total Final movement
3mm
PROOF LOAD TEST
ROCK ANCHOR - PROOF LOAD
Load
holding
period
movement
Rate of
movement
%
50- 100
50- 100
50- 100
minutes
mm
mm/minute
5
5
5
0.25
0.25
0.25
0.05
0.05
0.05
Holding+ movement total
k)
Total Final movement
0.8
1mm
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3 @ 5 MINUTE HOLDING PERIODS
100%
90 %
90
80
75 %
70
60
PROOF LOAD %
50 % PROOF LOAD
50
40
30
20
10
15 mm max (deadman)
0
DISPLACEMENT
Proof load = 70% Ultimate foundation design loading
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6.7.7
Pole foundations
a)
The Contractor shall provide equipment on site during the construction of the pole foundation
capable of loading the pole foundation to two-thirds of the maximum design moment.
b)
Where instructed by the Eskom Site Representative, the Contractor shall apply a construction
proof load test of two-thirds the maximum design moment to the completed pole.
c)
The pole foundation shall be loaded in increments of 50%, 75%, 90% and 100% and then unloaded
to 50% in 3 cycles of 50% to 100% of the proof test. If creep exceeds 1 mm/minute at ground
level, additional load shall be applied until the creep is less than the stated limit. The three 50%
loads and three 100% loads shall each be maintained on the pole for 5 minutes. If the creep is less
than 1 mm/minute, the final creep measurements shall be taken after each holding period. The
pole foundation shall be considered acceptable if the total ground level creep from 50% to 100%
load over 3 cycles is less than 30 mm. If the creep exceeds 30 mm, the foundation shall be
modified or replaced by the Contractor and re-tested.
d)
All pole foundation tests shall be conducted in the presence of the Eskom Site Representative.
7.
Towers
7.1
Tower Design
7.1.1
By the Employer
a)
If the Employer provides tower drawings (including but not limited to analysis, member selection,
bolt requirements etc.), it shall remain the responsibility of the Contractor to verify such drawings
are to his satisfaction. Although the Employer took all necessary measures to confirm the
accuracy and completeness of all tower drawings, it remains the responsibility of the Contractor to
report any inadequacies.
b)
Changes in tower configurations shall be reviewed and accepted by the Employer prior to
manufacture to ensure acceptability of any changed configuration.
7.1.2
By the Contractor
a)
If the Contractor prefers to make use of his own design of tower(s) other than those specified by
the Employer, these alternative tower designs must be submitted to the Employer for acceptance
prior to manufacturing or use.
b)
The Contractor shall be fully responsible for his designs and their satisfactory performance in
service. Acceptance by the Employer does not relieve the Contractor of responsibility for the
adequacy of the design, dimensions and details.
c)
Where the Employer provides general tower configurations, they act as a guide only to the
Contractor. Electrical clearances, cover angles, minimum phase spacing, tower heights etc., shall
be as shown on the conceptual drawings. The Contractor is encouraged to improve the towers
with respect to mass and aesthetics.
d)
Tower test loads will be provided. The towers shall be designed to withstand all the specified loads,
and shall be capable of withstanding construction loads during tower erection without special
handling equipment.
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7.2
Tower Manufacturing
7.2.1
Tower code numbers and marking
a)
New and existing tower designs accepted for manufacture will be allocated a tower code number
consisting of three digits, e.g. 422. This number is to be used in conjunction with the tower type
letters and tower descriptions given in the schedules to form the titles of the various towers.

For example:
Suspension tower type 422 A
0° - 15 ° Angle strain tower type 422 B
These titles are to be used on all correspondence, drawings, test reports, etc., relating to a
particular tower.
b)
Each tower member shall be allocated an identifying number, which shall correspond, to the
number on the appropriate tower erection and manufacturing drawing.
c)
The tower code number and the tower type letter are to be clearly stamped on every member of the
tower as a prefix to the member mark number. All steelwork shall carry a manufacturer's
identification marking consisting of a maximum of three letters. This shall be of the same letter
height as the number code. Acceptance of the marking shall be obtained prior to usage. These
marks shall be stamped before hot dip galvanizing and be clearly readable after hot dip galvanizing
and erection, e.g.: on back to back members these markings shall be on the flange without
stitches.
d)
Marking shall be done by stamping the marks into the metal with numerals or letters of 10mm
minimum height. The marking shall be consistently in the same relative location near the ends on
all pieces. No other marking shall be used.
e)
See also the requirements in 7.2.9 “Anti-theft measures and marking”
7.2.2
Tower steel standard
a)
Structural steel for all tower members, including all stubs and cleats embedded in concrete shall
conform to EN10025 Grade S355JR, and shall be hot dip galvanised after fabrication and marking.
b)
Certified mill test reports of the chemical and mechanical properties of the steel for the full quantity
required for fabrication shall be obtained from the steel supplier. Copies of these mill test reports
shall be retained at the Contractor's works for review.
c)
The Contractor shall, if so instructed, cut samples from deliveries of Grade S355JR steel and
conduct mechanical tests upon the samples to ensure that the steel is Grade S355JR. The
frequency of testing shall be subject to acceptance by the Design Engineer.
d)
Only structural shapes included in the latest edition of the "South African Steel Construction
Handbook", published by the South African Institute of Steel Construction, shall be used. Ensuring
the Availability of member shapes selected is the sole responsibility of the Contractor.
e)
To facilitate the transport of tower members, these shall be limited to a maximum length of 12.5 m.
f)
The steel selected for manufacturing purposes of poles and lattice structures should be suitable for
hot dip galvanizing. In general two steel types are acceptable namely “Aluminium Killed Steel” and
“Silicon Killed Steel”.
The chemical content of the steel should be within the following limits.
For Aluminium Killed Steel: Silicon (Si) = 0.01 to 0.04% and Phosphorous (P) = 0.015% maximum.
For Silicon Killed Steel: Silicon (Si) = 0.15 to 0.25% and Phosphorous (P) < 0.02% maximum.
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General tower steel fabrication
The following table summarises the main tolerances for the manufacturing of angles and plates
generally used in tower fabrication.
OPERATION
ANGLES
Straightness
Length of member = L (mm)
(after
manufacturing)
Leg length = h (mm)
PLATES / FLATS
For h ≤ 150 : Straightness = 0.4% L
For 150 < h ≤ 200 : Straightness = 0.2%
L
Dimensions
Leg length = h
(mm)
h ≤ 50
Permissible Variation
(mm)
Flats
Width = b (mm)
Permissible
(mm)
-1.0 to +1.0
50 < h ≤ 100
b ≤ 35
-1.5 to +1.5
-0.8 to 1.0
100 < h ≤ 150
35 < b ≤ 75
-3.0 to +3.0
-1.0 to +1.5
150 < h ≤ 200
75 < b ≤ 100
-3.0 to +3.0
100 < b ≤ 120
-2.0 to +2.5
Variation
-0.5 to +0.75
Thickness = t
t 40
-0.5 to +0.5
-1.0 to +1.0
-1.5 to +1.5
Plates
Nominal
thickness (t)
(mm)
Permissible
(mm)
Variation
-0.3 to +0.9
4.5 ≤ t < 5
5≤t 22 mm
Tolerance on final bending angle = ±1°
Backmark
Allowable offset from backmark = ±1 mm.
Allowable offset from backmark = ±1 mm.
Further tolerance requirement on holes:
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T = Plate or member thickness (mm)
T ≤ 16
16 < T ≤ 20
20 25
: α = 4°
: α = 3°
: α = 2°
: α = 1°
Figure 1
d = required diameter.
((D – d)/d) * 100 2m/s), “Armorflex” type paving (illustrated in Figure 5) should be used.
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FIGURE 10: WATER COURSE CROSSING, WITH GABION MATTRESSES OR ROCK /GRAVEL
FILLING ON GEOTEXTILE FILTER MATERIAL
6.4 LOW LEVEL BRIDGE OR CULVERT CROSSING (PIPES WITH CONCRETE SLABS)
Low level bridge or culvert crossings should be constructed and maintained bearing in mind the following:
The combined diameters of the pipes in the bed stream should be equal to the width of the water course,
that is, the distance from one embankment to the opposite embankment, and have a diameter of
approximately the depth of the 1 in 5 to10 year flood level.
The pipes should be laid with a cross-fall of 2 to 5 % on a 150mm+ thick concrete blinding layer. They should
be built-in at the ends with rock mortar walls (or gabions) and an in-between fill of rock or gravel mortar should
be used. The rock mortar walls and fill should extend well into the embankments (1to 2 m).
For higher water flow volumes and velocities, the top layer over the pipes should be a reinforced concrete
slab of  350mmthick.
Embankments should be built up with stone and mortar (or cells with gravel and mortar or other means for
example, gabions etc.) to about  0.3 m above the 5-year flood levels.
The riverbed should be protected for about 1 m upstream and  2 to 3 m down-stream with mortar stone rip
rap or Hyson cells with stone. Refer to Figure 11 for the design layout.
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Figure 11: River/water course crossing with pipes, rock /gravel mortar filling and concrete slab
7. TOWER SITES IN SLOPING TERRAIN
The majority of tower sites should be positioned such that access is possible with the minimum effort. While
due care and effort should be undertaken in the finalisation of tower locations, the presence of more suitable
tower positions may be made possible by minor adjustment in tower locations during construction. Where
relevant, this option is considered preferable over the construction of special access roads and platforms.
7.2 ALIGNMENT OF ACCESS TO TOWER SITES
The alignment of access roads in towers in sloping terrain must be planned by all relevant parties as outlined
in 0.
The alignment must suit access requirements for foundation construction and tower erection. Unless
precluded by environmental restrictions, the alignment must aim to provide access for a rough terrain crane,
rough terrain trucks, and 6-wheel drive concrete trucks.
The access alignment must also be suited to the tower footprint, as shown below. For guyed structures,
access may be aligned within the footprint of tower legs, while self-supporting towers may be suited to the
construction of access roads around the tower legs.
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Retaining walls
(introduced after
construction)
Concrete truck
access
9m
Crane
Platform
8m
Figure 12: Typical access to self-supporting lattice tower
Retaining walls
installed after
construction
around guyed
anchors
Concrete
truck
access
Crane
Platform
8m X
9m.
Guyed anchor
foundations
Figure 13: Typical access to guyed Tower
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Retaining wall
(introduced after
construction)
Tower position
Concrete truck
access
Crane
Platfor
m
9m
8m
Figure 14: Typical access to self-supporting pole
7.2 ACCESS FOR CRANES
The footprint for outriggers of a typical 80 ton crane is about 8 x 9m, however the outriggers need not be
placed of a completely level platform. The maximum crossfall slope for a rough terrain crane suited to
overhead line construction is about 5% or 1:20.
3m
9m
13 -14m
1m
Outrigger Shoring
8m
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Out riggers cross fall maximum allowance.
Figure 15: Typical 80 ton crane plan dimensions
Outrigger shoring, using railway sleepers or thick timber boarding will usually be required in areas with
significant crossfall.
8. REHABILITATION OF TOWER SITES AND ACCESS ROADS
At the completion of construction, repairs may be required on access roads to restore them to their original
condition.
Where berms have been eroded or worn away because they were constructed using unsuitable localised
material, alternative material for refurbishment and maintenance should be used. The following methods may
be considered:
Where the local material has high clay content or consists of a sandy soil with little variation in particle size,
the soil needs to be improved. The properties of the soil can be improved by the addition of stabilising
agents such as slaked lime in the case of clayey soils or cement in the case of sandy soils. The berm
material stabilised in this way should be mixed in the ratio of one part cement or lime to eight or ten parts of
soil. This material should be properly mixed, moistened, placed and compacted.
Borrow pits may be utilised to source more suitable material.
rehabilitation should be specified in the EMP.
The location of borrow pits, and their
Under normal circumstances, the majority of tower sites, being located on relatively even terrain, will not
require extensive rehabilitation or mitigatory measures. If the top-soil is replaced in the final layer of backfill,
natural ground cover vegetation will usually grow back in spite of extensive removal of surface vegetation
during construction.
Any soil removed by erosion, must be evenly filled back and, graded to conform to the surrounding terrain.
During foundation excavation, care must be taken to replace top-soil to the final layer of foundation backfill.
Failure to replace topsoil in the final layer will leave infertile sub-grade soil on the surface, thus impeding regrowth. The EMP may in certain instances also call for the re-planting or re-seeding of certain sites. All
tower sites should be rehabilitated (slope areas to be stabilized) and maintained by methods applicable to
the situation. Maintenance should be in accordance with the requirements of the EMP.
The following environments however, can constitute sensitive sites:
8.1 ARID ENVIRONMENTS OR SPARSE VEGETATION
These sites are typically located in areas of the Karoo and Namibian desert. The ground vegetation, when
disturbed, can take years to recuperate, and there is not sufficient natural moisture to permit re-planting of
natural flora.
The principle mitigatory measure is to limit the destruction of vegetation, by strict adherence to minimizing
the extent of damage. This includes limiting the available working area and avoiding the creation of multiple
tracks.
8.2 SLOPING TERRAIN
These tower sites require various forms of terracing. This not only ensures that erosion is limited but aids in
maintaining the uplift capacity of foundations, which is invariably compromised in sloping terrain.
The terraced soil requires the construction of soil retaining systems, which include the use of:

Stone walls, consisting of natural stone which are either loosely packed (adequate in mildly sloping
terrain), or laid using mortar.

Stone pitching, entailing the use of natural stone which is overlaid on the side slopes of terraces and
then cemented by mortar.
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Pre-cast-retaining systems, generally consisting of interlocking pre-cast concrete blocks.

Gabion mattresses, consisting of wire baskets which are filled with natural stone
The use of natural materials is favourable not only from an aesthetic, but also from a cost efficiency point of
view, and should be utilised where availability permits.
8.3 PROXIMITY TO FLOWING OR STILL WATER
Erosion of river banks have resulted in compromised tower foundations in a number of instances. In these
cases, it is preferable to utilise resilient systems, such as gabion mattresses. Gabion mattresses have the
added benefit that they are flexible, and continue to provide protection even after surrounding material has
been eroded (in contrast to other retaining systems, which can topple after heavy flooding).
9. POST CONSTRUCTION INSPECTIONS
The first post construction inspection should be conducted upon hand-over, and should be conducted jointly
by regional staff, project managers and engineers responsible for design.
The second (and most important) should take place 11 months after hand over, in order to asses:

the extent to which natural re-growth is possible

the erosion resulting from the preceding season, taking into consideration the amount of rainfall

the need for additional erosion protection or re-vegetation
10. EROSION PREVENTION STRUCTURES
These structures or systems are used in eroded areas and aim to control the flow of water, halt active
erosion and re-establish vegetation. Three categories of solutions are suggested by Suthers (2002). They
are:
10.1 HEAVY SYSTEMS
These solutions include concrete or brick structures and gabions and reno mattresses, etc.
10.2 GABION MATTRESS WALLS
Soils or up slope embankments which are subjected to dynamic or static loading must be stabilised to
ensure equilibrium of the surrounding environment. When soils is confined or loaded, distributing forces are
set up that may give rise to sliding, overturning and bearing failures. To counteract these effects slope
reinforcements may be required.
The specifications as referred to in SANS 1200DK should be taken in consideration when building Gabion
Mattress Retaining Walls.
The specifications and sketches in this document will refer to the protection of service roads against up-slope
rock and soil sliding which might damage the access / service road or prevent access along the service road.
The following schematic sketch will illustrate the layout of a Gabion wall. Dimensions will need to be
calculated according to the slope gradient, erosion risk and composition of the soil.
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Note: No single gabion cage will be longer than 4m.
Use double twist hexagonal woven mesh according to SANS 1580 specifications: use galvanised mild steel
wire.
Stone filling can be rock from the surrounding environment, primary crusher run, or obtained from an
approved source as indicated by the Employer or Technical Specification related to the specific project.
Backfill material behind structures and below structures to be compacted to a minimum of 98% MOD
AASHTO. A G200 geotextile to be used at all mesh / soil interfaces.
10.2 LIGHT SYSTEMS
These systems include Silk screens (van Heerden 2000) erosion control blankets, turf reinforcement mats
and geocells. The re-establishment of vegetation is also encouraged by using soil reclamation rolls (SRR),
EcoLogs or seeded coir mats.
150g/m2 UV RESISTANT SHADE
NETTING
600MM STRIP ON DOWNSTEAM
END
1.4m Y-STANDARD @
2m SPACING WITH
BACK -STAY
400 mm
400 mm DEEP TRENCH
(BACKFILLED
AND
COMPACTED)
400 mm
63 x 2.5mm GALV. WIRE MESH
500 mm
2 x 2mm GALV. WIRE
WRAP @ 250mm SPACING
Figure 16: Silt Screen used for rehabilitation of eroded areas
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11. REFERENCES
Matthee, J F and Van Schalkwyk, C J, A Primer on soil conservation publication- 2001
Eskom Specification, Environmental Impact Control
Department of Agriculture
(EIC/385) , Eskom-Transmission , March 1985
Eskom Specification, Environmental Impact Management Program (ESKPVAAZ1),
Jan 2000
Eskom-Transmission ,
Eskom Specification, Transmission Line Towers and Line Construction (TRMSCAAC1 rev.3) , EskomTransmission , March 2001
Eskom Publication, The fundamentals and practice of Overhead line Maintenance, Power series vol.2, 2002
Determination of longitudinal grades on rural roads, Polus, et. al., Israel Institude of technology, 1995
Eskom Transmission Guideline -Soil Erosion Guideline, 41-337, 2010
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Annex D - Electrical safety earthing during construction
Introduction to safety earthing
When stringing and regulating conductors close to a parallel energized line(s), and when transferring
conductor onto suspension and strain hardware and when fitting jumpers at strain towers, there is a real risk
for workers to get injured or killed as a result of induced voltage and current.
This risk can be avoided by applying safety earthing in two levels, namely 1 set of working earths on either
side of the work sites, and an additional set of earths further away (master earth). It is also assumed that
proper earthing tools are used, and that earthing will always be applied and be removed using an insulated
earth stick.
The main aim of the earthing described above is to create a preferred path for induced energy (described in
engineering terms as electrostatic and electromagnetic induction which leads to measurable voltage and
current levels). It is further implied that the worker should never become part of the electrical circuit through
the rigorous application of the working earths.
Note that the earthing system that is designed and intended to be part of the operation of the line during its
lifecycle is to be seen as a separate earthing system.
Internationally, line construction contractors are required to apply the safety earthing principles as laid down
in in the following standards, including the adherence to earthing equipment specifications:
Of particular interest is the IEEE Standard 524 which explains in good detail how the safety earthing
principles are working and how the contractor should proceed to do the various activities from the stringing
phase until the conductor installation work is finished.
The equipment details that are most pertinent can be summarized as follows:
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Example of insulated earth sticks
The induced voltages and currents that pose a risk
If either the master earths or the working earths cannot be connected to a tower’s steel (to use the tower’s
earthing system), it is specified that rod earths be driven into the ground and tested to see that a low enough
resistance is achieved for it to be effective. This is an area where contractors should be strictly monitored to
make sure that the correct technique and equipment is used to verify the effectiveness of drive rod
temporary earth electrodes. Although it will not always be possible to achieve low ohm values, there is a
suggestion on the table that a value below 100 ohms be achieved. If this value is not achieved by the first
driven rod, it implies that more rods be driven in a crow’s foot arrangement and interconnected with leads.
The two figures below demonstrate the capacitive coupling and magnetic coupling situations. In practice, a
mix of the two coupling mechanisms will be present. The magnetic coupling mechanism can be more
dangerous especially if the workers on site do not understand how it actually manifests itself. A single earth
applied to a conductor which is subjected to magnetic coupling phenomena is a death-trap waiting for the
worker to touch it to complete and set the circuit up to conduct electrical current.
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With a single earth in place, the electrostatic induction (which would be present if energized parallel lines are
energized but not carrying current) can be dealt with quite effectively using only 1 earth (instead of the
worker providing that path to earth).
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When there is no voltage on the parallel energized lines but if they carry current, which is admittedly an
unlikely scenario but used here for explanatory purposes, the worker is facing a lower risk when no earths
are applied than when 1 earth is applied. If only 1 earth is in place, the worker becomes the second earth
which completes the electrical circuit for current to be conducted.
As soon as more than 2 earths are applied, the chances of the worker becoming a preferred path for
electrical current is reduced. When two working earths are applied on both sides of the work site, and two
master earths further away, redundancy in the temporary earthing system is provided and the risk to the
worker is reduced to a very low level.
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Avoiding induced voltage and current effects during construction activities
The use of running blocks with a traveler ground is suggested by the IEEE 524 standard and
provides a very good security system against accidental electrocution when transferring
conductors from running blocks onto insulator assemblies. These devices also provide an
additional remote earth connection at each suspension tower.
In summary, the following activities and procedures are potentially risky in terms of steady state (50Hz)
induced electrocution:

Stringing a new line close to parallel energized lines or when crossing them

Regulating and fitting of dead-ends, and transferring conductors from running blocks on
suspension towers to the insulator hardware

Fitting of jumpers on strain towers

Dismantling of conductor from an old line that runs in parallel or crossing existing energized lines
Transient coupling, from lightning or switching impulses, although far less likely to occur at a critical moment
in time, will also be limited to a large extent if the 50Hz steady state induction risk is properly eliminated.
This is a suggested retro-fit to convert standard running blocks so that traveler grounds are added.
conversion of standard running blocks
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Annex E – Foundation and Pressure Grouted Micro Pile Nominations
Test Pit Excavation
The minimum soil investigation requirement shall be the number of test pit excavations as per the figure
below, to allow for the in-situ inspection of the soil. The test pits shall be excavated outside the zone of
influence of the appropriate foundation, and shall be taken down to a depth equal to the lesser of the depth
of the foundation system to be constructed or 3m. No consession shall be granted by Eskom with a view to
reduce the number of test pits excavated.
A minimum of two test pits are required for self-supporting tower structures, both on the center line and in
the midst of any two foundation legs (ie. leg A –B and leg D-C or leg B-C and leg A-D). An example is
depicted in the figure below, Tp1 and Tp2.
A minimum of three test pits are required for guyed V tower structures, two on the center line and in the
midst of any two foundation legs (ie. leg A –B and leg D-C or leg B-C and leg A-D) and one at an
approximate distance of 2metres from the center foundation, leg E on the other center line. An example is
depicted in the figure below (ie.Tp1, Tp2 and 2m away from leg E, Tp3).
A minimum of three test pits are required for cross rope tower structures, all three on the center line in a
row. Two in the midst of the two foundation leg A–B and leg D-C and one at dead center of the two mast
foundations (leg E and F). An example is depicted in the figure below (Tp1, Tp2 and at dead center of the
mast foundations, Tp3).
Soil Profiling
The soil profile is a record of the vertical succession of the different layers of soil as they occur at any
particular location on a site. Soil profiling standards shall be in accordance with SANS 10161. Each
stratum/layer should be described in terms of its moisture condition, colour, consistency, structure, soil type,
and origin (MCCSSO). If properly described in terms which may be readily interpreted by the engineer, the
soil profile provides basic information for the approximate quantitive assessment of the properties of the
materials. The figure below is a summary of the identification and classification of soils using the MCCSSO
description method that should be used. There recording of each soil profile must be captured on Eskom
Contractor’s Soil Profile Sheet and a summary of all the soil type assessments to be recorded on Eskom
Soil Nomination List, both are displayed below. Photograph should be of good quality of at least
5megapixels, and must clearly illustrate the entire depth of the profile with the following test pit information
on a board, above the soil test pit; Tower type and number, and test pit number and tower leg letter.
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THE STANDARD FOR THE CONSTRUCTION OF
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Project No:
Quality preformed by - Signature
TITAN FOUNDATIONS
Activity No and description
Project description
Installation of anchors.
As to M S.
Logging of drill profiles
Anchor setting out.
M S and TRMSCAAC5 cl 6.5.1 h)
Profile Anchor hole's logs with all the following: (a) drill
depths layers-soil type 1or 3 or soft or hard rock. (b) grout
pressure (c) grout mix
(d) anchor type
(e) sleeve tubes
top of anchor (f) drawing No's (g) Anchor rod rake/angle
±100 and single in line guy anchor to be in 30
Cap stub /link and anchor positions and spacings
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
Type of Control
ACTION
X
CONTRACTOR
X
X
X
X
X
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QUALITY INSPECTION PLAN - FOUNDATION CONSTRUCTION
Instruction / Procedure / Drawing /Inspection
/Template or Specification or Reference
Method Statements (MS) and Specification: 240-47172520
(TRMSCAAC5)
Tower setting out. Centre peg
Foundation set out drawings (clear of any objects, roads, water
position Foundations setting
courses-dongas, fences, embankments slope edges etc..)
out positions
Excavation Barricading
Check stub /link position, Check rebar, Shuttering, Remove
grout around top end of anchor and leave 150mm for
construction joint into cap and install anchor plates and nuts.
Photographs must be taken before casting of concrete.
Profile hole drilled and flushed Profile hole's log (as to M S) with all the following: (a)
with water.
Contractor's nomination: soil type 1or 3 or soft or hard rock.
(not part of foundation)
( b) drill depths to layers etc.
Cap Installation
Check concrete delivery time, do slump tests and take concrete
cube samples. M S , Works information and TRMSCAAC5 cl
6.6.10.
(Environmental requirements for line completion check)
Cap top sloped and edges chamfered.
M S and TRMSCAAC5 cl 6.6.13 and 6.6.5
Concrete casting
compaction(vibration) of cap
Concrete finishing and curing
Clean tower site
Test cube results 7 and 21
M S and TRMSCAAC5 cl 6.6.6
day results
Construction proof load test
M S and TRMSCAAC5 cl 6.7.5
on Guy anchors
Ultimate Load test -block
M S and TRMSCAAC5 cl 6.7.1
anchor(deadman), pile or rock
Review all relevant inspection
and test records
MEASUREMENT
, CHECK,
INSPECTION,
LEG B
LEG C
LEG D
Mast E
2
Remarks, Deficiency or
Non-conformance Report
numbers
Revision
TOWER AND FOUNDATION NUMBER
LEG A
at
Mthis
S -point
Method Statement
I - Inspection Point: A predetermined stage in the Quality product/process plan where a inspection or check or measurement must be preform to verify parameters and specification requirements.
T - Test / measurement check or action to be preformed
S - Surveillance - general observation
W - Witness point
H - Hold Point: A predetermined stage beyond which work shall not proceed without the attendance of and written authorization of a Eskom representative and photographs must be taken
Definitions:
DOCUMENT
ESKOM COPYRIGHT PROTECTED
When downloaded from the WEB, this document is uncontrolled and the responsibility rests with the user
to ensure it is in line with the authorized version on the WEB.
Document Classification: Controlled Disclosure
Unique Identifier: 240-47172520
Revision:
5.2
Page:
101 of 104
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Project:
Leg:
Pile1
Description of flushed matrial at depth
intervals (Colour, Grain Sizes, Sand, Clay
Powder etc.) Hard or soft soil,
Hard or soft rock
Pile No.
Drilling / Piling Date
Drilling / Piling Time
Titan Rod Size
Drill Bit / Cutting Head1 Type
and Diameter
Drilling Depth 1st layer
Drilling Depth 2nd layer
Drilling Depth 3rd layer
Drilling Depth 4th layer
Max Grouting Presure (Bar)
Amount of Joints and drilling
rods
Grout / Water / Cement Ratio
Centralizer / Spacers
Guide tube position (150mm min
into cap bottom level)
Plate& nuts Installed and
secured
Earth cable connections
Photos
Name
A
Pile 3
Pile 4
Pile1
Pile 2
Pile 4
Pile1
Pile 2
Profiles Hole /s Information
Pile 3
Pile Information
B
Tower No.:
Tower Foundation Inspection - Titan Micro Pile Foundations
Pile 2
Notes
Eskom Representative
Piling Accepted and Released for Construction of Pile Caps
Signature
C
Pile 3
Date
Document Type
Unique Identifier
0
Inspection Report
To Be Confirmed
Pile 3
1
D
Revision
Tower Type:
Pile1
Pile 2
Total Pages
Pile 4
Pile 4
ESKOM COPYRIGHT PROTECTED
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to ensure it is in line with the authorized version on the WEB.
Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
102 of 104
Annex F- Built Documentation Format
As built Documentation format
The latest As Built Specification should be adhered to.
On completion of construction the contractor, in conjunction with the project manager, is required to compile
the final as built document as per the requirements outlined below.
Outline of Requirements
General Line Data
Project Name, Client, Eskom Contract No., Contractor Name.
Line
Data Category
Line Voltage
Circuits
Configuration
Phase Conductor
Jumper Conductor
Earth Conductor
OPGW
OPAC (Optical Approach Cable)
Insulators
Route Length
Tower Types
Guyed Suspension Tower
Self‐supporting Suspension Tower (0˚ to 3˚)
Self‐supporting Tension Tower (0˚ to 15˚)
Self‐supporting Tension Tower (15˚ to 35˚)
Self‐supporting Tension Tower (35˚ to 60˚ / 0˚
Terminal)
Self‐supporting Transposition Tower
ESKOM COPYRIGHT PROTECTED
When downloaded from the WEB, this document is uncontrolled and the responsibility rests with the user
to ensure it is in line with the authorized version on the WEB.
Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
103 of 104
Contractor details

List of Sub-Contractors and their scopes of work.
Foundation and Tower Schedules

Soil Profiles and Foundation Norminations Checking Lists

Earth Resistance Checking Lists (Must include recording of soil and weather conditions)

Tower Assembly and Erection Checking Lists
Stringing Records
OPGW Installation

OPGW Schematic Layout

Colour Coding and Numbering

Power Meter Results and OTDR Reports

Splice Performance Summary

Power Line Carrier Frequencies

Joint Box Positions

Assembly Drawings

OPGW Specification
Electrical line parameters (measurements to be carried out as per specification
474-9428 – transmission line impedance measurement specification)
Drawings

Foundation Drawings

Tower Outline Drawings

Hardware Drawings and OPGW Hardware

Manufacturers Insulator Drawings (compare with maximum size from assembly drawings from LES
– normally connecting length should be the value specified in the assembly drawing with tolerance
of 10mm – designer may ask for a higher tolerance of 1mm or 2mm for certain special projects)
(including sample testing results of dimensions etc..) Can also include a measurement done by
LES engineer, with any Eskom test that may have been conducted)

Grading Rings
Hardware

Midspan Joints

Spacers/Spacer Dampers (Include Drawing)

Assembly Drawings

Insulated Earth Wire Assemblies and Non-Standard Assemblies

Damping Devices

Miscellaneous Items (Aircraft warning spheres, bird diverters, warning lights, etc.)

Hardware Type/Sample Test Results

Hardware Problems and Non-Conformances during Construction (Fitment issues, failures, etc.)

On-site conversions to cater for special requirements
ESKOM COPYRIGHT PROTECTED
When downloaded from the WEB, this document is uncontrolled and the responsibility rests with the user
to ensure it is in line with the authorized version on the WEB.
Document Classification: Controlled Disclosure
THE STANDARD FOR THE CONSTRUCTION OF
OVERHEAD POWERLINES
240-47172620 (TRMSCAAC 5.2)
Unique Identifier: 240-47172520
Revision:
5.2
Page:
104 of 104
Line Profiles
incidents, near-misses , accidents and fatalities
Aerial Laser Scan (AS-BUILT LIDAR)
HD Visuals and Corona Checks from Flyover (Crossings)
Line walkdown and Line Audit (Ticksheet) – Including Galvanometer results etC OBTAINED FROM THE
DESIGN LEADER
Latest as-built profiles, staking table with corresponding as-built tower numbers.
Handover Certificates
Permits

Statutory Permits

EMP Permits

Major Incident Reports

Non-Conformance Reports

Concessions
TxSIS

TxSIS Upload Form

TxSIS Data
ESKOM COPYRIGHT PROTECTED
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to ensure it is in line with the authorized version on the WEB.
Standard
Title: FIBRE OPTIC CABLE SYSTEM
ACCEPTANCE TESTING
Technology
Unique Identifier:
240-70732888
Alternative Reference Number: N/A
Area of Applicability:
Engineering
Documentation Type:
Standard
Revision:
2
Total Pages:
16
Next Review Date:
August 2021
Disclosure Classification:
Controlled
Disclosure
Compiled by
Approved by
Authorized by
Vanessa Naidu
Cornelius Naidoo
Richard McCurrach
Senior Engineer
Telecommunications T&S
Manager
Senior Manager PTM&C
Date:
Date:
Date:
Supported by SCOT/SC
Ziyaad Gydien
SCOT/SC Chairperson
Date:
PCM Reference: 240-5348797
SCOT Study Committee Number/Name: Telecommunications
Document Classification: Controlled Disclosure
FIBRE OPTIC CABLE SYSTEM ACCEPTANCE TESTING
Unique Identifier: 240-70732888
Revision:
2
Page:
2 of 16
Content
Page
1.
Introduction .................................................................................................................................................. 3
2.
Supporting clauses ...................................................................................................................................... 3
2.1 Scope ................................................................................................................................................. 3
2.1.1 Purpose .................................................................................................................................. 3
2.1.2 Applicability ............................................................................................................................ 3
2.2 Normative/informative references ...................................................................................................... 3
2.2.1 Normative ............................................................................................................................... 3
2.2.2 Informative ............................................................................................................................. 3
2.3 Definitions ........................................................................................................................................... 3
2.3.1 General .................................................................................................................................. 3
2.3.2 Disclosure classification ......................................................................................................... 3
2.4 Abbreviations ...................................................................................................................................... 4
2.5 Roles and responsibilities .................................................................................................................. 4
2.6 Process for monitoring ....................................................................................................................... 4
2.7 Related/supporting documents .......................................................................................................... 4
3.
Requirements .............................................................................................................................................. 4
3.1 Splice Acceptance Procedure ............................................................................................................ 4
3.2 Fibre Optic Testing Procedure ........................................................................................................... 5
3.3 End-to-end fibre optic link Characterisation ....................................................................................... 7
3.4 Documentation ................................................................................................................................... 8
4.
Authorisation ................................................................................................................................................ 9
5.
Revisions ...................................................................................................................................................10
6.
Development team ....................................................................................................................................10
7.
Acknowledgements ...................................................................................................................................10
Annex A – Sample of Splice Loss and ORL Summary Table ..........................................................................11
Annex B – Sample of Power Source and Light Meter Summary Table ...........................................................13
Annex C – - Sample of PMD measurement summary table.............................................................................14
Annex D – Sample of CD measurement summary table ..................................................................................15
ESKOM COPYRIGHT PROTECTED
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to ensure it is in line with the authorized version on the WEB.
Document Classification: Controlled Disclosure
FIBRE OPTIC CABLE SYSTEM ACCEPTANCE TESTING
1.
Unique Identifier: 240-70732888
Revision:
2
Page:
3 of 16
Introduction
This procedure covers the testing of newly-installed Fibre Optic Cable Systems as well as any subsequent
repair to existing installations.
2.
Supporting clauses
2.1
Scope
This procedure covers the testing of Fibre Optic Cable Systems within Eskom. These systems may consist
of Optical Ground Wire (OPGW), All Dielectric Self Supporting (ADSS), Externally Attached Cable, Duct
Cabling or a combination of the above.
This procedure will form part of the fibre installation or repair Contract.
2.1.1
Purpose
The purpose of this document is to detail the requirements for the testing of Fibre Optic cables in Eskom.
2.1.2
Applicability
This document shall apply to Transmission and Distribution.
2.2
Normative/informative references
Parties using this document shall apply the most recent edition of the documents listed in the following
paragraphs.
2.2.1
Normative
[1]
ISO 9001 Quality Management Systems.
[2]
NRS 061-2 Specification for Overhead Ground Wire with Optical Fibre – Part 2: Installation
Guidelines
[3]
NRS 078-2 ADSS Specification for All Dielectric Self-Supporting Fibre Optic Cable - Part 2
Installation Guideline
[4]
NRS 088-2 Duct or directly-buried underground optical-fibre cable : Part 2 : Installation Guidelines
2.2.2
Informative
[5]
Setting Splice Specifications for Single-Mode Fibre Cables – Corning White Paper WP7114
[6]
Single Fibre Fusion Splicing – Corning Application Note AN103
[7]
Testing Procedure for Network Deployment – EXFO Application Note 086
[8]
ORL Measurements in Field Applications – EXFO Application Note 140
[9]
QM-58: Eskom Standard: Supplier Contract Quality Requirements Specification
2.3
Definitions
2.3.1
General
None
2.3.2
Disclosure classification
Controlled disclosure: controlled disclosure to external parties (either enforced by law, or discretionary).
ESKOM COPYRIGHT PROTECTED
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to ensure it is in line with the authorized version on the WEB.
Document Classification: Controlled Disclosure
FIBRE OPTIC CABLE SYSTEM ACCEPTANCE TESTING
2.4
Unique Identifier: 240-70732888
Revision:
2
Page:
4 of 16
Abbreviations
Abbreviation
Description
10GigE
10 Gigabit Ethernet
ADSS
All dielectric self- supporting fibre optical cable
APC
Angle Polished Connector
CD
Chromatic Dispersion
FEC
Forward Error Correction
NCS
National Calibration Service
ODF
Optical distribution frame / Patch panel
OPGW
Overhead ground wire with optical fibre
OTDR
Optical time domain reflectometer
PC
Polished Connector
PMD
Polarisation Mode Dispersion
RL
Reflectance Loss
SDH
Synchronous Digital Hierarchy
2.5
Roles and responsibilities
Installation or repair work by the contractor is to be supervised by the Projects Department or the relevant
Grid personnel. Acceptance testing is to be performed by Works Planning and Centralised Services
Department or as otherwise specified by the Grid/Regions Secondary Plant Manager.
2.6
Process for monitoring
Not applicable.
2.7
Related/supporting documents
The document superseded by this document is TPC 41-5, Fibre Optic Cable System Acceptance Testing.
3.
Requirements
3.1
Splice Acceptance Procedure
a)
All splice joints shall be done using a core alignment optical fusion splicer, splice losses shall
comply with the following standard:
Fibre Splice Loss
Single Mode Fibre
Maximum Splice Loss
Mean Splice Loss
≤ 0.15dB
≤ 0.05dB
Multi Mode Fibre
Maximum Splice Loss
Mean Splice Loss
≤ 0.15dB
≤ 0.07dB
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Document Classification: Controlled Disclosure
FIBRE OPTIC CABLE SYSTEM ACCEPTANCE TESTING
Unique Identifier: 240-70732888
Revision:
2
Page:
5 of 16
Notes:
1)
The Splice loss is the numerical average of an individual splice as measured in both directions with an Optical Time
Domain Reflectometer (OTDR).
2)
The mean splice loss is the sum of all individual splice losses on a particular fibre divided by the total number of
splices on that fibre. Mean splice loss requirement is only relevant if the fibre optic link possesses five or more
splices.
b)
Any joint which has a splice loss that is higher than the specified value shall be broken and redone
a minimum of three times. If the optical loss in the joint cannot be contributed to micro bending and
it is still not within specification after three splice attempts, a note to this effect shall be made in the
test documentation. OTDR test results to this fact must submitted as part of the documentation as
proof.
3.2
Fibre Optic Testing Procedure
a)
The aim of these tests is to satisfy the Customer that the fibre optic installation is acceptable.
b)
After installation, or repair, the complete system shall be tested from end to end. The Customer
shall be given the opportunity to carry out final acceptance testing in conjunction with the
Contractor’s staff. The Customer’s presence shall not relieve the Contractor of his responsibility for
the satisfactory performance of the equipment during site testing and thereafter through to the end
of the warranty period.
Note: Before any optical tests are carried out, it must be ascertained that all of the fibre cores are matching 1 to 1. This should
be verified using a Power Meter and Light Source end-to-end.
c)
Note:
For cable systems with one or more joints in the total length (excluding joints in Fibre Distribution
units) the following tests is required: Optical Time Domain Reflectometer (OTDR) Testing,
reporting the following results (i.e. attenuation coefficient, length and position and loss of splice
joints, event Reflectance Loss (RL) and link Optical Return Loss (ORL)) should be made in
accordance with IEC 60793-1-40.
Set the OTDR length range at least as long as the fibre under test to avoid ghosting and echoing.
These
phenomena are particularly evident at short lengths (35dB (PC type connectors on Patch Panel)

>55dB (APC type connectors on Patch Panel)
Pay attention to cleaning of connectors before connecting fibre under test or test cord.
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Document Classification: Controlled Disclosure
FIBRE OPTIC CABLE SYSTEM ACCEPTANCE TESTING
Unique Identifier: 240-70732888
Revision:
i)
2
Page:
6 of 16
For attenuation measurement, the test equipment wavelength tolerance shall be within ±20nm of
the central wavelength for 1310nm and 1550nm and ±10nm for 1625nm.
1)
line lengths up to 50 km attenuation measurements shall include all three test wavelengths.
2)
lines in excess of 50 km wavelength tests 1550nm and 1625nm is required.
3)
Under certain conditions and for low bit rate protection links, ESKOM could accept 1310
and 1550nm test results with prior consent for links up to 50km.
4)
Multimode Fibres require wavelength tests 850nm and 1300nm.
5)
Where fibre length is less than 200m only light source and Power Meter testing is required
(no OTDR).
j)
The overall link (end-to-end) loss (attenuation) must be indicated in the summary sheet (Appendix
1).
k)
Event loss and attenuation measurements shall be based on bi-directional results when using the
OTDR and in one direction using the light source and Power Meter.
Tests using a Power Meter and Light Source should be concluded before using an OTDR to ensure 1 to 1
matching of the fibre cores. Test results that include the above information must be submitted in a RAW unedited format additionally test results must be submitted in abbreviated format as per Appendix A.
Note: The OTDR manufacturer’s software must be used to analyse and calculate bi-directional splice loss.
l)
Bi-directional measurements with the same test conditions are required to eliminate the effects of
backscatter coefficient differences. The loss calculation must be done on the OTDR manufacturer
software, offline calculation using any other software is not allowed as it cannot be guaranteed.
m)
Ensure the Event Analysis; Event Thresholds and Event Notifier are set for maximum detection.
The following table for OTDR Maximum pulse widths must be adhered to:
Range
Maximum Pulse Width
2km and 20km and 50km
2 500ns
> 80km
10 000ns (10µs)
The following information must be available as part of the actual test result;
1)
Date and Time (Test was done)
2)
Fibre Optic Cable Description,
3)
Fibre Number
4)
Test Direction (Site A and Site B)
5)
Index of Refraction, Helix Factor and Rayleigh Backscatter Coefficient.
The following documentation must be submitted as part of Test Results
1)
OTDR documentation stating (make, model, specifications)
a. Copy of the offline trace analysis software used for trace and bidirectional analysis.
b. Calibration certificate from the manufacturer, approved service centre or NLA accredited facility with
a date not older than two years.
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Document Classification: Controlled Disclosure
FIBRE OPTIC CABLE SYSTEM ACCEPTANCE TESTING
2)
Unique Identifier: 240-70732888
Revision:
2
Page:
7 of 16
Splice machine information / documentation
a. Make, model, specifications
b. Service record / letter from manufacturer, certified service centre or NLA accredited facility, with a
date not older than two years.
c.
Record must include all service history on the equipment
Information must be summarised in table form as shown in the example in Appendix A of this Document.
n)
The end-to-end loss (ODF to ODF) must be measured from both ends using a light source and an
optical power meter. Results for 1310nm, 1550nm and 1625nm windows are required for all fibre
lengths.
Details of the instrumentation launch conditions and reference shall be provided in the documentation called
for in clause 3.4. The results must be summarised in table form as shown in the example in Appendix B of
this Document.
o)
Commissioning shall be done in close co-operation with, and to the full satisfaction of the relevant
Eskom Department.
p)
Eskom reserves the right to have several/multiple technicians actively participate in the fibre
section link tests with the object of them gaining intimate knowledge of the testing procedures.
3.3
End-to-end fibre optic link Characterisation
a)
Prior to the final acceptance of the fibre installation the link it shall be characterised for Polarisation
Mode Dispersion (PMD) and Chromatic Dispersion (CD) as a requirement for assessing its overall
acceptability and for the selection and configuration of the optical transmission equipment to be
used.
b)
The end-to-end PMD performance shall be measured, from one end only, for each fibre, using an
IEC acceptable test method. Measurements shall be done across the O (1260 to 1360 nm) & C
(1550nm to 1565nm) bands and the measured r.m.s. value of the PMD shall be documented in the
form shown in Appendix D.
Note: Recommended maximum acceptable PMD figures for equipment operating at various data rates are as follows:
Bit rate
(GBit/s)
Maximum Average PMD
(ps)
PMD Coefficient
2.5
40
< 2.0
10
10 (with no FEC)
< 0.5
40
2.5

Tender Documents:

Invitation to tender Ref PSCED0332 The refurbishment of the Impala Hillside Athene 1 & 2 132kV bypass lines.pdf
Eskom - Standard Conditions of Tender.pdf
240-47172520 TRMSCAAC5.pdf
240-70732888 FIBRE OPTIC CABLE SYSTEM.pdf
Athene Hillside Impala 1 2 132kV Bypass Refurbishment DRA Report.pdf
Athene Hillside Impala Bypass Technical Evaluation-List of technical tender returnables.pdf
ST_240-110403330- OPGW hardware and installation spec_.pdf
Annexure C Local content declaration COMPLETE AND RETURN.pdf
Annexure D Imported content declaration COMPLETE AND RETURN.pdf
Annexure E Local content declaration COMPLETE AND RETURN.pdf
Eskom Integrity Pact COMPLETE AND RETURN.pdf
C0 ECC3 Cover Page Impala Athene 1 and 2 132 kV Emergency Bypass Refurbishment.doc
C1 1 ECC3 Offer and Acceptance Impala Athene 1 and 2 132 kV Emergency Bypass Refurbishment.doc
C1 2a ECC3 Data by Employer Impala Athene 1 and 2 132 kV Emergency Bypass Refurbishment.pdf
C1 2b ECC3 Data by Contractor Impala Athene 1 and 2 132 kV Emergency Bypass.doc
C2 ECC3 Pricing Data Option B_Impala Athene 1 and 2 132 kV Emergency Bypass Refurbishment.doc
C3 1 ECC3 Employers Works Information Impala Athene 1 and 2 132 kV Emergency Bypass.pdf
C4 ECC3 Site Information Impala Athene 1 and 2 Emergency Bypass Refurbis....doc
Bill Of Quantities Impala Athene Hillside 132kV Bypass Refurbishment.xlsx
B 240-77471499 Acknowledment Form for Eskom SHE Rules.docx
20200213_C5 240-108987034 Env Tender Evaluation and Scoring Card (High Risk).doc
1. Contractor Pre Work File Assessment (TRM-FM-0095).docx
32-726 SHE Requirements for the Eskom Commercial Process.pdf
20181015_240-109832932 Baseline EMP for Suppliers Contractors.xls
A 240-77433139 Supplier risk category.docx
Impala Hilside Athene Bypass_240-109832932.pdf
Annexure B.pdf
HIGH RISK WORK REV 2.pdf
32-136 - Construction, Safety Health and Envrionment Procedure.pdf

Related Tenders:

The following tenders are possibly related to this tender due to tenders coming from different sources.