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Tender No.W 0686 WTE Part C3: Scope of Work

Mdloti River Development: Hazelmere Dam Raising

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Contents PART C3: Scope of Work

C3.1 STANDARD SPECIFICATIONS ............................................................................................. 110 C3.2 PROJECT SPECIFICATIONS ................................................................................................ 111 C3.3 PARTICULAR SPECIFICATIONS .......................................................................................... 121



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C3.1 STANDARD SPECIFICATIONS The standard specifications on which this contract is based are the South African Bureau of Standard

Standardized Specifications for Civil Engineering Construction SABS 1200. (Note to complier “SABS” has

been changed to “SANS”.

SANS 1200 & 0120

The following standardised specifications shall apply to this contract:

SANS 1200 A : General (including AD Small Dams)

SANS 1200 C : Site Clearance

SANS 1200 G : Concrete (Structural)

SANS 1200 HA : Structural Steelwork

SANS 1200 L : Medium Pressure Pipelines

SANS 1200 LC : Cable Ducts

These standardised specifications are not bound into this document nor issued with it. The Contractor may

purchase copies for his own use from SABS, Pretoria

British Standard Code of Practice

B1 - BS 8081 1989 : Ground Anchors

This standard specification is included in Volume 3 (CD inserted in back page pocket of Volume 2).

The Particular Specification constituting additions and amendments to the Standard Specification is included

in C3.3 of this section of the Tender Document, Part C3: Scope of Work.

Other Particular Specifications

B2 – Drilling

B3 – Water Pressure Testing of Boreholes

B4 – Grouting

The above Particular Specifications are included in their entirety in C3.3 of this section of the Tender

Document, Part C3: Scope of Work.

DWA Standard Specifications

B5 – DWS 0750; Water Retaining Concrete

B6 – DWS 9900 Section C6; Corrosion Protection of Platforms, Ladders, Handrails & Flooring

B7 – DWS 9900 Section C1: Corrosion Protection of Steel Pipes and Specials for Pipelines

B8 – DWS 1110; Construction of Pipelines

B9 – DWS 1180: Specialist Services

B10 – DWS 2510: Supply of Valves – Gate Valves

These standard specifications are included in Volume 3 (CD inserted in back page pocket of Volume 2).



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C3.2 PROJECT SPECIFICATIONS

C.3.2.1 Locality and Location Information

a) General

Hazelmere dam is located approximately 5km north of the town of Verulam on the Mdloti River in KwaZulu-

Natal, sited directly 30km due north of Durban and 500km south east of Johannesburg. By road from Durban

the distance is 38.3kms (41 min.) and by road from Johannesburg 617kms (7hrs 7 min.).

b) Accessibility

The locality and location plans are presented in Volume 2: Book of Drawings reproduced at approximate

scales of 1:300,000 and 1:15,000 respectively. As illustrated on the Location Plan access to the dam wall is

gained via the existing gravel road, which runs from the Vincent Dickenson main road turn-off, to the base of

the dam wall a distance of 2.42 km.

The existing gravel access road has the following basic characteristics, relative to 0.0m chainage, located at

the junction with the south channel of Vincent Dickenson Road.

Length (m) Width (m) Length (m) Gradient (m)

0 –320 5.0 – 5.5 0 – 940 1:15 – 1:10 (7%-10%)

320 – 2,420 3.0 – 3.5 940– 2,420 1:30 – 1:25 (3%-4%)

The contractor shall be required to increase the width of the access road wherever he considers such

improvement necessary for the safe operation of two way construction vehicles and shall be required to

maintain the road and side drainage in a safe and workmanlike condition throughout the duration of the

contract. On completion of the works the road must be re-gravelled with Type G5 material to ensure a 200

mm thick running surface and completely re-graded and re-compacted to regular falls.

c) Land for Contractor’s Operations

Three areas have been identified on which the contractor may set up operations and these are indicated on

the Location Plan C41.2/2. The area immediately adjacent to the dam wall, belonging to the Employer, has

been designated the “Working Area” and has an estimated gross area of around 2.4 hectares and a

perimeter of approximately 650 metres. This is considered the primary working area with direct access to the

dam wall for all construction operations. Two hundred metres of the dam wall security fencing lies within this

area. This fencing shall have to be removed to facilitate construction operations and shall be replaced with a

new fence on completion of the works. Additionally, there are around 5 survey beacons within this area that

will require to be fully protected by the contractor throughout the construction period. Any survey beacons

that are destroyed or become displaced as a result of the contractors operations and are thus rendered

unusable shall be reinstated at the expense of the contractor.

The area designated as the “Site of the Works” has been indicated on the Tender Drawing 466 471/12 and

amounts to 14.7 hectares the “Contractors Working Area” is also shown on this drawing and is contained

within the Site of the Works.

The other two areas designated as “Potential Base Camp Accom. & Storage (2.5 ha)” and “Potential

Alternative Base Camp Accom. & Storage” are considered as being potentially suitable for the establishment

of the contractor’s workers accommodation and additional storage of equipment and materials. The first of

these areas is located approximately 420m from the Vincent Dickenson main road turn-off and 2 kms from

the dam wall base camp. This is private land and unfortunately the owner is unknown. Should the contractor

consider this additional area suitable for his operations then he must make his own arrangements for

acquisition or lease.



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The second, less desirable and more remote, area is located to the south east of the dam wall, with access

along an informal, low grade access route. The Mdloti River runs along the west flank of the area. Again this

is private land but the owner is known and this information can be made available to the tenderer on request.

Should the contractor consider this additional area suitable for his operations then he must make his own

arrangements for acquisition or lease.

The Contractors construction camp shall be fenced off and shall contain all offices, stores, workshops,

testing laboratories, toilet facilities, etc. The camp shall always be kept in a neat and orderly condition.

The Contractor shall be responsible for providing and maintaining his own security arrangements for the

duration of the Contract.

The Contractor shall not use the area nor allow it to be used for any purposes not directly associated with the

execution of the Contract.

The Contractor shall be responsible for arranging, at his own cost, for the provision of all services he may

require in the area, as well as elsewhere on the Site.

The tendered sums as scheduled by the Contractor, whether grouped or individually, shall include all costs

for the installation, maintenance and removal of the fencing as specified, in addition to all other facilities

specified and as required by the Contractor for his own purposes.

No housing is available nor shall be allowed on the site of the works for the Contractor’s employees. It is the

sole responsibility of the Contractor at his own cost to house his employees and transport them to and from

the site. Only night-watchmen may be on the Site after hours.

C.3.2.2 Project Description

a) General

Hazelmere dam is the responsibility of the Department of Water Affairs (DWA). The Department has in turn

vested the authority for all operation and maintenance aspects in Umgeni Water, who maintain operational

offices at the dam. The offices are located on the north flank of the dam wall as indicated on the Location

Plan included in Volume 2: Book of Drawings, with GPS coordinates 29°35’46.6”S 31°2’29”E

This shall be the meeting point for the site briefing and site inspection scheduled as indicated in the Tender

Notice.

Hazelmere dam is a concrete gravity arched type structure 478m long with a centre line radius of 725m and

incorporates a 103m long ogee spillway situated 60m from the right bank end. The maximum height of the

structure above the lowest foundation level is approximately 47m. The dam was completed in 1976 and was

originally designed and built to accommodate a proposed 7m increase in dam height by means of the

installation of steel gates.

The project now under consideration includes raising the dam’s existing full supply level (FSL) from that of

86.0 m.a.s.l to 93.0 m.a.s.l. The raising thereby increases storage capacity and enables the dam operator,

Umgeni Water, to provide a reliable source of water to meet the demand of the rapidly growing urban and

industrial users within the supply area. In order to prevent critical water shortages in the supply areas the

need to raise the dam has become crucial.

b) Operational Condition

To assist construction operations on the dam wall the Department of Water Affairs have analysed their

historical dam capacity data. From the graph shown below it has been concluded that it will be safe to draw



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down the dam and operate it at 70% of the operating level for the duration of the contract period, implying

that the dam has a small risk of dropping to the 30% level if the abstractions are the same as historic.

However, it must be emphasised that during construction the dam must be regarded as a strategic

operational water supply source and that even with controlled draw down there is a risk of discharge over the

spillway during periods of continuous rainfall or flooding. The contractor must therefore take account of this

risk when planning and implementing construction operations on the spillway and adjacent sections.

In this regard the Contractor’s attention is drawn to Clause 8.8.6 of the Particular Specification

c) Piano Key Weir (PKW)

It has been determined that the most appropriate means of raising the dam is by installation of a reinforced

concrete Piano Key Weir (PKW). This will be constructed atop the existing ogee spillway. A PKW provides a

much extended spillway length, by introducing a hydraulically and geometrically designed (planemetrically)

castellated weir wall. The increased length is evident when the original straight ogee spillway length of 103

metres is compared with the PKW length of 630 metres. This PKW is a first for South Africa and is arguably

the largest of such installations worldwide.

The general dimensions are:

Length (weir top) 630 m

Width 21.6 m

Plan (top) surface area 2,225 m2

The walls vary in height tapering from a minimum of zero to a maximum of 9.0m.

The entire weir structure shall be built to exacting standards and to water retaining structure specifications,

including provision for incorporation of waterproofed expansions joints. The vertical walls have a tapered

profile, ranging from 500mm at the top to 800mm at the bottom, incorporating closely spaced, large diameter

bar reinforcement, all aimed at achieving a design crack width of 0.1mm. As the site will be subject, at times,

to extremes of weather such as high solar radiation, high air temperatures and strong drying winds, then

particular care will be required at all stages of the concreting cycle to ensure that the matrix and final set

concrete is not adversely affected.



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d) Grout Curtain

The recent geotechnical investigations at the dam concluded that the grout curtain, especially in the spillway

section, has been compromised. Further investigations indicated that the majority of the pressure relief holes

at the bottom drainage gallery are clogged with material that originated from the mica rich layers in the

substrata of the dam wall foundation and from the dam basin (large organic content). Water pressures of

between 10m and 12 m were measured during the recent drilling of the additional boreholes from the bottom

gallery where artesian water conditions were encountered.

There are also indications that water is flowing through flow paths in the dam foundation which may seriously

damage the foundation in the longer term if not rectified. Restoration of the grout curtain will restrict and

control this flow.

The stability of the present and raised dam structure must be improved and the installation of anchor cables

has been identified as the most acceptable method. In terms of sequence of operations it is essential that the

restoration of the grout curtain be done in advance of the cable installation. Consequently anchoring

conditions in the foundation may well be better understood on completion of the re-grouting operation and

this may well prove beneficial in determining enhancements to the detailed design of the anchors.

e) Ground Anchors

Ground Anchors are to be incorporated to safeguard the stability of the dam wall when raised to the new Full

Supply Level (FSL). A system of vertical anchors through the wall crest as well as inclined anchors through

the downstream face of the dam wall will be installed. In both the Spillway and Auxiliary Spillway sections of

the wall, the heads of the anchors will need to be recessed into the dam wall in order to facilitate the flow of

water over the wall. The installation of the anchors will increase the wall stability against sliding and

overturning.

The specification applies to the supply, installation, stressing and testing of 379 No. post-tensioned anchors,

each with a working load of 3400 kN. Post-tensioned anchors shall be installed in drilled holes expected to

be of the order of 275mm nominal diameter.

The number of anchors has been derived from the basic assumption of a 3400kN working load per anchor.

However, the Contractor shall if he considers it advantageous and with the Engineer’s approval, vary the

anchor capacity taking due account of the geotechnical information and the in-situ concrete core results,

contained in the respective reports available in Volume 3 of the contract documents.

The anchors are to be generally fabricated, installed, stressed and tested in accordance with “BS8081:1989

Ground Anchorages” and any alternate design proposal by the Contractor should also be in accordance with

this British Standard.

It has been deemed beneficial to allow for cutting out existing concrete in the dam wall and installing precast

anchor bearing blocks (complete with water tight sealable lids) underneath the anchor heads where bearing

block dimensions are similar. Where dimensions vary (inclined anchors at the auxiliary spillway downstream

face) it is envisaged that in-situ concrete will need to be used. The Contractor may wish to propose alternate

anchor bearing blocks based on the core results of the in-situ concrete found in Volume 3 of these

specifications.

Furthermore, installation of anchor load monitoring equipment has been included in this contract by way of

hydraulic pressure transducer load cells and associated equipment. Breaking out existing concrete in order

to cast in ducting for read-out lines from the load cells has also been allowed for. In light of the above, the

Contractor may wish to propose alternate performance monitoring equipment to measuring the loads in the

anchors.



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C3.2.3 Survey Information

The Department of Water Affairs approved beaconing system relevant to the Hazelmere Dam Raising

contract, consists of eleven permanent beacons all prescribed by the letter “P” they are:

Reference Y (westing) m X (southing) m Elevation m

P03 -4060.169 3275228.241 121.280

P05 -4415.487 3275613.941 73.954

P07 -4344.216 3275646.229 72.613

P08 -4245.744 3275492.391 65.862

P09 -4214.942 3275413.134 74.876

P10 -4157.362 3275338.361 89.144

P108 -4239.661 3275684.93 95.484

P109 -4171.168 3275605.744 95.468

P143 -4054.655 3275380.153 95.473

P214 -4277.174 3275717.118 89.333

P243 -4062.281 3275369.295 91.722

The tabulated coordinate values are all based on the World Geodetic System 1984 ellipsoid, commonly

known as WGS84, with the International Terrestrial Reference Frame 91 (ITRF91, epoch 1994.0)

coordinates of the Hartebeesthoek Radio Astronomy Telescope used as the origin of the system. This

system is known as the Hartebeesthoek94 Datum. At this stage all heights still remain referenced to mean

sea level, as determined in Cape Town and verified at the tide gauges in Port Elizabeth, East London and

Durban.

These principal beacons shall be used for all setting out purposes in relation to the construction works and

the contractor must take great care to ensure that these beacons are protected from damage at all times.

The contractor shall also be responsible for carrying out regular checks on all beacons in this referencing

system to ensure their accuracy remains uncompromised for the duration of the works.

C3.2.4 Engineering Geology and Site Investigation

The geological report for the Hazelmere Dam Raising contract was undertaken by the engineering geological

consultant Knight Hall Hendry and is entitled “ENGINEERING GEOLOGICAL REPORT FOR THE RAISING

OF THE DAM: SITE INVESTIGATIONS” and is referenced KHH1953/3110012907 and dated June 2012.

The report is summarised in its “Section - 7. Conclusions and Recommendations” as follows:

The site is underlain by red brown coarse grained arkosic to subarkosic sandstone; of the Natal Group. The

rock mass behaviour is strongly influenced by the distinct bedding planes, which often contains thick

interbedded micaceous/silty materials. These were mostly not recovered and resulted in core losses.

It can be concluded that the grout curtain has been damaged by (i) movement of the dam as a result of shear

or high tensile stresses below the dam; or (ii) by leaching of the grout by seepage of water from the dam. It

must further be concluded that the existing drainage holes are blocked since they hardly produce any

seepage.

The results of the drilling, water flow, camera survey and pressure measurements paints a rather gloomy

picture of the spillway section with possibly a damaged grout curtain, inoperative drainage system and a

continuous zone of high permeability (and associated uplift pressures) at depths varying between about 2m

and 9m below the concrete/rock interface.



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It is recommended that the upper 20m of the grout curtain be reinstated using stable grout injection

processes and the drainage holes be properly cleaned out or redrilled to ensure effective release of pore

pressures.

The results of this investigation confirmed that the shear strength parameters assumed for the foundation

rock mass of c=0 and phi=38° are realistic. Evidence was found that bedding planes are continuous over at

least 7 block widths and contain substantial thickness of interbedded silty/micaceous materials. These

prominent, continuous bedding planes have on average a 5m interval, with numerous bedding planes in

between of limited continuity.

A full copy of this report accompanies and therefore forms an integral part of these tender documents. The

tenderer is required to study the document carefully and to fully acquaint himself with the contents thereof.

C3.2.5 Labour-Enhanced Construction

a) General

It is an objective of the Employer to maximise the labour content of certain operations or portions thereof on this

Contract. In this regard, where the specified work allows for a choice between mechanical or labour-enhanced

means, the former should generally be kept to the practical minimum.

b) Preferential Recruitment Area and Local Labour Composition (% of Total Number of Staff)

Preference will be given to persons from areas closest to the project workplace (Hazelmere Dam). The

following are regarded as communities closest to the workplace in the order of priority as set out below:

i. Persons residing within the municipal areas immediately adjacent to the dam.

ii. Persons residing within the municipal area of the District Municipality

iii. Persons residing within the KZN Province

iv. Persons residing within the rest of the Republic of South Africa.

50% of the labour should thus be recruited from the areas as defined above.

c) Requirements

The Contractor shall take cognisance of these objectives and their contribution to the utilisation of labour when,

at tender stage, he commits on the anticipated labour content required to complete the contract.

It is a requirement that the minimum labour content for this contract will be 20%.

The Contractor is required to supply detailed records of labour content with the monthly payment certificates in

a format approved by the Engineer.

C3.2.6 Affirmative Black Enterprises (ABEs)

It is a requirement of this contract that for the procurement of goods, services (including work carried out by

ABE subcontractors) and materials from affirmative black enterprises (ABEs), an amount of 15% expressed as

a percentage of the contract price (excluding VAT, Contract Price Adjustment (CPA), Contingencies, Variations

on Special Materials, Lump sums and all Provisional and Prime Cost amounts) be achieved.

Preference will be given to the following groups:



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A "black enterprise" (BE) is one that is 50,1% owned by black persons and where there is

substantial management control. Ownership refers to economic interests while management

refers to the membership of any board or similar governing body of the enterprise.

A "black empowered enterprise" (BEE) is one that is 25,1% owned by black persons and where

there is substantial management control. Ownership refers to economic interests. Management

refers to executive directors. This is whether the black enterprise has control or not.

A "small, medium and micro enterprise" (SMME) bears the same meaning assigned to this

expression in the National Small Business Act, 1996 (Act No. 102 of 1996).

Local enterprises within the project area (iLembe Municipality area).

The target value of goods, services and materials (excluding VAT) procured from external sources from the

following designated groups expressed as a percentage of the 15% of the goods, services and materials

required (excluding VAT) shall at least be:

Black enterprises: 15%

Black empowered enterprises: 20%

Local Enterprises 5%

Small, medium and micro enterprises 10%

A record will be kept of percentage value per group. Achievement of targets is to be monitored monthly.

Penalties will be applied at the end of the contract if targets are not met.

C3.2.7 Failure to Comply with Provisions

Failure or refusal on the part of the Contractor to take the necessary steps to ensure that the targeted ABE

content and labour content is met, shall be sufficient cause for the Engineer to deduct penalties as follows:

a) Labour content

Penalty = CP x 3% x (specified labour content % - actual labour content %).

CP is the contract price excluding VAT, Contract Price Adjustment (CPA), Contingencies, Lump

Sums, Variations on Special Materials and all other Provisional and Prime Cost amounts.

b) ABE content

Penalty per group = CP x 0,5% x (specified ABE group content % - actual ABE group content %).

CP is the contract price excluding VAT, Contract Price Adjustment (CPA), Contingencies, Lump

Sums, Variations on Special Materials and all Provisional and Prime Cost amounts.

C3.2.8 HDI Supervisory Staff

If personnel are hourly paid they cannot be classified as supervisory staff, regardless the nature of their duties.

Examples of relevant personnel are, site agent, assistant site agent, senior materials technician, senior

surveyors and clerks.

The minimum value of HDI supervisory staff expressed as a percentage of the total number of supervisory staff

employed on the contract, as proposed by the tenderer shall be 30%.

A historically disadvantaged individual (HDI) means a South African citizen:



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who, due to the Apartheid policy that had been in place, had no franchise in national elections

prior to the introduction of the Constitution of the Republic of South Africa, 1983 (Act No 110 of

1983) or the Constitution of the Republic of South Africa, 1993 (Act No 200 of 1993) ("the interim

Constitution); and/or

who is a female; and/or

who has a disability.

Provided that a person, who obtained South African citizenship on or after the coming to effect of the Interim

Constitution, is deemed not to be an HDI.

C3.2.9 EMP Requirements

The Environmental Management Plan (EMP) is included in Volume 3: Specialist Reports and Standard

Specifications and forms an integral part of these tender documents. It has been developed to mitigate

construction impacts associated with the proposed raising of the Hazelmere Dam. Principles and instructions

contained in this document are to be implemented by the Contractor and his employees.

The EMP has been updated with the conditions of the Record of Decision (ROD).

Non-compliance with the provisions of these documents will thus be regarded as a breach of the construction

contract. Compliance with the EMP will be enforced through monthly audits carried out by the Environmental

Compliance Officer (ECO).

C3.2.10 Quality Assurance, Quality Control and Quality Plan

Within three weeks of the award of the contract the Contractor shall furnish the Engineer with a

comprehensive Quality Assurance and Control plan that incorporates all the requirements of the documents

comprising the contract, for his own quality management as well as describing the Quality Control process

that will provide for regular inspection and signing off of work by the Engineer’s Site Staff. This will

particularly apply to aspects of the work that will be covered such as the checking of rebar and other

embedded items before the placing of concrete. The Quality Plan will provide all forms and documentation to

be signed by inspectors as necessary to generate a complete record of Quality Management.

The Quality Management System shall comply in all respects with the requirements of the ISO 9000-9004

series (as applicable). The Quality System shall take the form of a coordinated and formally documented

statement and shall include quality management objectives, policies, organisation, procedures, and work

instructions that demonstrate the Contractor's implementation of the requirements of ISO 9001 - 2000 Code

for Quality Management Systems.

The Contractor's Project Quality Plan for the Contract shall indicate how the Contractor's Quality System

shall apply to the specific requirements of the Contract. It shall clearly indicate, by way of written description,

schedules, flow diagrams and procedures, compliance with ISO 9001 - 2000 and compliance by Sub-

Contractors to ensure compliance with ISO 9001, 9002 or 9003 - 2000, as appropriate to the classification of

the product or service.

The Project Quality Plan shall identify all documentation concerning implementation of the procedures and

will form part of the demonstration of conformance to requirements for the plant materials and equipment to

be supplied under this Contract.

The Project Quality Plan shall be subject to the Engineer's approval.

The vocabulary used shall comply with the requirements of ISO 8402-1994.



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The onus to produce work that conforms in quality and accuracy of detail to the requirements of the

Specifications and Drawings rests with the Contractor, and the Contractor shall, at his own expense, institute

a quality control system and provide experienced engineers, foremen, surveyors, materials technicians, other

technicians and technical staff, together with all transport, instruments and equipment to ensure adequate

supervision and positive control of the Works at all times.

The cost of supervision and process control, including testing carried out by the Contractor, will be deemed

to be included in the rates tendered for the related items of work.

C3.2.11 Existing Services

a) Water, Electricity and Sewerage

The Contractor shall, at his own expenses, be responsible for obtaining and distributing water and electricity

required for construction and domestic use. The distribution of water and electricity shall be carried out in

accordance with the applicable laws and regulations.

No separate payment will be made for obtaining and distributing water and electricity, the cost of which will

be deemed to be included in the tendered rates.

b) Buried Services - General

The record drawings included in Volume 3: Specialist Reports and Standard Specifications provide the best

information available for existing services and the Contractor’s attention is drawn to these drawings.

Before underground or excavation work is carried out, the Contractor shall ascertain the presence and

position of all services likely to be damaged or interfered with by his activities. He shall obtain up-to-date

plans from the Engineer, Employer and local authorities for this purpose, showing the position of services in

the area where he intends to work. As services can often not be reliably located from such plans, the

Contractor shall determine the exact position of such services by means of suitable detecting equipment and

afterwards by careful hand excavation where necessary in order to expose the services at the positions of

possible interference by his activities. This procedure shall also be followed in respect of services not shown

on the plans but believed to be present.

All such services, the positions of which have been located at the critical points, shall be designated as

'known' services and their positions shall be indicated on a separate set of Drawings, a copy of which shall

be furnished to the Engineer.

While he is occupying the Site, the Contractor shall be liable for all damage caused by him to known services

as well as for consequential damage, whether, caused directly by his operations or by the lack of proper

protection.

The Contractor shall exercise all the necessary care to prevent damage to known services during

construction operations. Major excavating equipment and other Plant shall not be operated dangerously

close to these services. Where necessary, excavation in close proximity to these services shall be carefully

carried out with suitable hand tools, excluding picks wherever their use could damage the services.

No additional payment will apply to such more difficult work.

Services left exposed shall be suitably protected from damage.

c) Treatment of existing services

Existing services shall be relocated or removed as indicated on the drawings only at the instruction of the

Engineer.

d) Damage to services



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Damage that occurs to unknown services during construction will be paid by the Employer.

However, all services that have been located and exposed, and are subsequently damaged by the

Contractor or his subcontractor, shall be reinstated to the same state as it was before the damage occurred

at the time and cost of the Contractor.

e) Reinstatement of services and structures damaged during construction

The Contractor shall inform the Engineer immediately when a service or structure is damaged. The extent of

the damage and a proposal how to reinstate the service or structure shall be submitted to the Engineer on a

sketch with dimensions and time frames.

The Contractor shall not be allowed to reinstate any service or structure unless indicated so by the Engineer.

The Contractor shall render all reasonable assistance to the service or structure owner with the

reinstatement of the service or the structure if required.

The Contractor shall be liable to reinstate the service or structure to its original state.

C3.2.12 Recording of Weather

The Contractor shall be responsible for keeping accurate records of weather conditions in the Daily Site

Diary, to use as substantiation of any claim for extension of time..

The Contractor will inform the Engineer when he is unable to proceed with the works in accordance with the

approved contract program. Subject to the approval of the Engineer, the rainfall and other relevant notes will

be noted in the Daily Site Diary for the applicable day/s. After the event the Contractor shall provide a revised

contract program motivating if the delay affects his schedule to the extent that he will need to motivate for an

extension of time in accordance with the Contract.

The Engineer, together with the Employer, shall be responsible for granting the extension of time.

C3.2.13 As-Built Drawings

During the execution of the Works on the Site the Contractor shall, in a manner approved by the Engineer,

record on Working Drawings and Contract Drawings all information necessary for preparing As-built

Drawings of the installed Contract Works. Marked up Drawings and other documents shall be made

available to the Engineer as he may require for inspection and checking.

As-built Drawings may, subject to the approval of the Engineer, include approved Working Drawings

adjusted as a correct record of the installation of the Contract Works.



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C3.3 PARTICULAR SPECIFICATIONS

These Particular Specifications constitute additions and amendments applicable to the Standardised

Specifications.

C.3.3.1 Additions and Amendments to SANS 1200

PS A GENERAL

7. TESTING

7.2 APPROVED LABORATORIES

Append sub-clause 7.2 with the following:

The Contractor shall secure the services of an approved laboratory to oversee site activities related

to concrete quality, slump and strength sampling and testing. The method statement and

procedures for the quality control of the concrete are to be approved by the Engineer before

commencement of the work. Should the approved laboratory elect to establish a suitable concrete

testing facility on site, it will be operated by the Contractor with full access permitted to the

Engineer. All work related to sampling and testing, carried out on site, shall be supervised by a

suitably qualified and experienced laboratory technician.

8. MEASUREMENT AND PAYMENT

8.1 MEASUREMENT

8.1.2 Preliminary and General Item or Section

8.1.2.2 Tendered sums

Append sub-clause 8.1.2.2 with the following:

d) All Subcontractors’ direct costs and overhead costs, profit and all other costs for the provision of

the item.

8.3 SCHEDULED FIXED-CHARGE AND VALUE RELATED ITEMS

8.3.2 Establishment of facilities on the Site

8.3.2.1 Facilities for Engineer

The sum tendered shall allow for the Contractor shall provide offices and facilities as specified in

PSAB sub-clause 3.2 and for these offices to be equipped with the following for shared use by the

engineer’s staff:

a wireless network including modem and router;

One multifunction document solution machine with capabilities to copy, scan, email and fax

documents up to A3 in size.

One A1 colour Plotter.

Two 10megapixel, 3x optical zoom digital camera supplied complete with 4mb memory card.

8.3.2.2 Facilities for the Contractor

The rate for all items under this sub-clause must cover the cost of complying with the requirements

of clause 11.1.1 of the EMP in Volume 3 of the Contract Document

c) Laboratories

The sum shall also cover the cost of complying with clause PS A 7.2 above, to which the

Contractor’s attention is drawn.

d) Accommodation

Accommodation will not be permitted on site but the sum tendered shall allow for all costs the

Contractor may incur for accommodation of staff in the area as outlined in the Project

Specifications.



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e) Ablution and Latrine facilities

The sum shall also cover the cost of complying with clause 11.1.3 of the EMP in Volume 3 of the

Contract Document, to which the Contractor’s attention is drawn.

i) Access


Contract Document and any improvements to the access in terms of clause C3.2.1b above, to

which the Contractor’s attention is drawn.

j) Plant

The rate shall also cover the cost of complying with clause 11.1.2 of the EMP in Volume 3 of the


8.3.3 Other Fixed Charge Obligations

The rate shall also cover for the cost of complying with all fixed charge aspects of the EMP

included in Volume 3 of this Contract Document

8.4 SCHEDULED TIME- RELATED ITEMS

8.4.2 Operation and Maintenance of Facilities on Site, for Duration of Construction, except where

otherwise stated

8.4.2.1 Facilities for Engineer

a) Furnished offices

The Sum tendered shall also allow for the Contractor to service the engineers’ offices on a daily

basis and to maintain the following in working order:

a wireless network including modem and router.

One multifunction document solution machine with capabilities to copy, scan, email and fax

documents up to A3 in size.

One A1 colour Plotter.

b) Telephone

No telephone will be required but the sum tendered shall allow for the Contractor to pay for the

monthly data usage of the Engineer’s Site wireless.

d) Survey assistant and material

The rate shall cover the cost of providing the personnel and equipment listed in PS AB Clause

5.5. On completion of the works, ownership of the survey equipment shall revert to the

Contractor.

New Item:

Append sub-clause 8.4.2 with the following:

e) Accommodation

The Contractor shall pay for the accommodation for the Engineer’s Site Staff as directed by the

Engineer.

f) Transport

The Contractor shall pay for the transport for the Engineer’s Site Staff as directed by the Engineer.

8.4.2.2 Facilities for the Contractor

The sums tendered for all items under this sub-clause must cover the cost of complying with the

requirements of clause 11.1.1 of the EMP in Volume 3 of the Contract Document



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c) Laboratories

The sum shall also cover the cost of complying with clause 7.2 above, to which the Contractor’s

attention is drawn.

d) Accommodation

Accommodation will not be permitted on site but the sum tendered shall allow for all costs the

Contractor may incur for accommodation of staff in the area as outlined in the Project

Specifications.

e) Ablution and Latrine facilities



i) Access


Contract Document and any improvements to the access in terms of clause C3.2.1b above, to

which the Contractor’s attention is drawn.

j) Plant



8.4.5 Other Time Related Obligations

The sum shall also cover the cost of complying with all time-related aspects of the EMP included in

Volume 3 of this Contract Document

8.6 PRIME COST ITEMS

a) Eel Ladder

In terms of the EIA provision is to be made for the installation of an eel ladder in order to allow

passage of eels to and from the upper reaches of the Mdloti River. In view of the fact that studies in

this regard are not yet conclusive in terms of what is required, a stated sum for the work has been

included in accordance with indications that have been made.

1) Stated sum for study and implementation

The Contractor shall pay for the above as directed by the Engineer.

2) Overheads, charges and profit on (1) above

b) Electrical Installation

The stated sum for this item constitutes provision for the appointment of an electrical contractor to

install cabling and fittings as necessary to reinstate lighting and any other electrical installation

disrupted by the works. The ducting and draw pits required for the installation are measured

elsewhere.

1) Electrical installation as directed.

The Contractor shall pay for the above as directed by the Engineer.

2) Overheads, charges and profit on (1) above.

c) Environmental

The stated sum for this item constitutes provision for carrying out a search to find rare and

endangered flora species in an inundation area in the dam basin and reporting on an action plan to

rescue these species and relocate them to a newly established nursery. It further allows for

actioning the plan in the report and maintaining the nursery on a monthly basis for 12 months. The



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sum also allows for the removal of trees greater than 100mm girth from the dam basin over an area

of approximately 175 Hectares.

1) Stated sum for implementation

2) Overheads, charges and profit on (1) above

8.7 DAYWORKS

Certain routine structural and/or concrete repairs must be carried out on the existing dam wall and

other installations. Where so required the Engineer may use the provisions made under the

Dayworks items in the bill of quantities to attend to such remedial work.

8.8 TEMPORARY WORKS

8.8.6 Special Water Control

The Umgeni Water staff operating the dam will attempt to lower the dam to 70% of its capacity in

order to lower the dam supply level to facilitate construction work. Notwithstanding the

aforementioned steps, these measures will not be able to guarantee control of the supply level.

The contractor shall allow here for the design and construction of a coffer dam or some other

method of protecting the works (or relevant portion thereof) from damage or disruptions resulting

from water levels within the dam rising due to flooding, sudden heavy rainfall or un-seasonally high

rainfall within the dam catchment that prevents dam operating staff from maintaining the lowered

supply levels.

It is envisaged that the protection will be required during the early stages of the construction of

each PKW (Portion of the PKW situated on an individual dam wall monolith) and the lump sum is

for the provision of the number of structures required as well as the consequent movement of a

structure to each position in which it will be required.

In this regard the historical top water level data is provided in C3.2.2b of the Project Specifications

for the Contractors information



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PS AB ENGINEERS OFFICE

1. SCOPE

Append clause 1 with the following:

The location and details of the site office accommodation shall be approved by the Engineer before

construction.

3. MATERIALS

3.2 OFFICE BUILDINGS

Replace sub-clause 3.2 with the following:

The contractor shall provide and furnish offices/rooms for the use of the engineer comprise of the

following:

Resident Engineer’s office – shall consist of one room with a floor area of at least 16m2 and a

ceiling height of 2.5m.

Internal furnishings to include:

a) One trestle table, 2m long x 1m wide x 0.9m high, with a smooth top.

b) Two desks of minimum dimensions 1,5m long x 0,9m wide with four drawers (two lockable).

c) One high stool.

d) One office swivel chair, two visitors’ chairs.

e) A lockable upright steel cabinet with three shelves and a lockable steel filing cabinet with four

drawers.

f) Shoe cleaning mat at entrance.

g) An acceptable blind to each window.

h) A pin board, 3m long x 1,20m high for displaying plans and diagrams.

i) Acceptable lighting.

j) Acceptable air-conditioning unit of minimum 12000BTU output.

k) Two 220V 15A wall socket with computer extension sockets (1 to 4 type).

l) OZA File System or equal approved (12 Clips and 1 Movable holder) for storage of AO size

drawings.

Assistant Resident Engineer’s office – shall consist of one room with a floor area of at least 12m2

and a ceiling height of 2.5m.



b) One desk of minimum dimensions 1,5m long x 0,9m wide with four drawers (two lockable).

c) One high stool.

d) One office swivel chair, one visitor’s chair.


drawers.








drawings.

Engineering Technicians’ office – shall consist of one room with a floor area of at least 16m2 and a

ceiling height of 2.5m.





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b) Three desks of minimum dimensions 1,5m long x 0,9m wide with four drawers (two lockable).

c) One high stool.

d) Three office swivel chair, one visitor’s chair.


drawers.








drawings.

Meeting/boardroom – shall consist of one room with a floor area of at least 24m2 and a ceiling

height of 2.5m.


a) One boardroom table, 4m long x 2m wide x 0.9m high, with a smooth top

b) 12 boardroom chairs.

c) Shoe cleaning mat at entrance.

d) An acceptable blind to each window.

e) A white board.

f) Acceptable lighting.

g) Acceptable air-conditioning unit of minimum 18000BTU output.

h) Four 220V 15A wall socket with computer extension sockets (1 to 4 type)

Kitchenette – shall consist of one room with a floor area of at least 9m2 and a ceiling height of

2.5m.


a) Cupboard of 3m long x 1m wide x 1.1m high.

b) Crockery and cutlery sufficient for six people.

c) Shoe cleaning mat at entrance.

d) An acceptable blind to each window.

e) Acceptable lighting.

f) Two 220V 15A wall socket with computer extension sockets (1 to 4 type).

g) A 300l fridge.

h) A 20l microwave.

i) A suitable kettle.

j) A sink with cold water tap.

The Contractor shall also supply a toilet for the exclusive use of the Engineer’s Site Staff.

On completion of the works, ownership of the building and their furnishings shall revert to the

Contractor who shall remove them from the Site.

4. PLANT

4.1 TELEPHONE

No telephones shall be supplied by the contractor but the cost of the Engineer’s Site Staff mobile

phone monthly usage shall be paid by the Contractor as Detailed in PSA sub-clause 8.4.2.1 b).

5. CONSTRUCTION

5.5 SURVEY ASSISTANTS

The Contractor shall supply the following certified and calibrated equipment and staff:

Two suitably qualified and experienced survey assistants.



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One Engineer’s automatic level, carrying case plus tripod and telescopic levelling staff

(including levelling bubble attachment).

6 ranging staves graduated metrically.

Two plastic coated steel tapes of lengths 30m and 100m.

Levelling and tachometer books as required.

Cover meter capable of measuring within the specified tolerances



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PS C SITE CLEARANCE

5.7 Append sub-clause 5.7 with the following:

During dis-establishment the contractor shall rehabilitate, including reseeding where necessary, the

portions of the works used for offices, laydown yards, laboratories, other works areas, etc.

5.8 Append sub-clause 5.8 with the following:

DEMOLITION OF STRUCTURES

a) Precast concrete barriers

There are two types of concrete barriers (upstream and downstream) shown on the drawings.

These barriers along with the coping will have to be removed.

The weights are as follows:

Coping – 300 kg/m

Upstream – 1 450 kg/m

Downstream – 1 200 kg/m

b) Concrete road screed

There is a concrete screed lightly reinforced (mesh Ref 194) to be removed.

c) Concrete bridge surface slab

The concrete bridge surface is a reinforced concrete structure bonded to the precast I beams.

There are several built in items which must be catered for (vents and shutter-boards).

Volume is 90 m3 (or 230 t)

The stabilising in-situ cross beams must be demolished.

Volume is 12 m3 (or 30 t).

The rubble must be prevented from falling onto the spillway ogee crest or into the lake.

d) Precast prestressed I beams

The precast prestressed I beams spanning the 7 x 13m openings will have have to be removed in

an orderly manner. (Note – The exact fixing to the main concrete lintel beam is unclear possibly

only the concrete bridge slab reinforcing)

No off = 42

Length = 14m (Approximate mass 10 t)


e) Concrete Lintel beam

The lintel beam is envisaged as a heavily reinforced concrete beam cantilevering out from the

abutments and the piers. There are expansion joints at the midpoint of each 13m beam.

The volume of concrete is approximately 750 m3 (or 1 850 t).

The demolition work must follow a strict procedure designed to limit the un-balancing of the

cantilevers and the Contractor will be required to submit a method statement that will indicate, inter

alia, the removal of equal sections alternatively on each side of the pier support.


f) Concrete piers and Abutments

The piers and sections of the abutments (minor) must be removed to top of ogee crest.

The volume of concrete is approximately 1 650 m3 (or 4 050 t).


g) Cut back on ogee spillway

This entails demolition and scabbling of ogee surface to create a suitable key for the PKW base.

The extent of the work is shown on the drawings.



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h) Cut trenches in existing dam wall structure

Cut trenches as indicated on drawings for embedment of ducts for electrical and telemetry

installation. These trenches will be either 100x100mm or 225x225mm and will be cut on top of the

dam wall or on the sloping face of the dam wall.

i) Cut pockets for precast anchor heads

These pockets are to receive the anchor live ends as detailed on the drawings.

j) Bore holes through concrete for PKW aeration system

Large diameter holes to be formed in the existing dam to provide aeration ducts for air entrainment

into water spilling over the PKW and new Roberts Splitters as indicated on the drawings.


8.2 SCHEDULED ITEMS

8.2.8 Demolish and Remove Structures

The rates shall cover all costs to supply, set up and operate specialist equipment as well as any

temporary work to provide platforms from which to operate in order to demolish structures, break

out concrete or bore large diameter holes all described in Clause 5.8 above, with due care and skill

and in strict accordance with a detailed Method Statement to be provided by the Contractor for the

Engineer’s approval before demolition work commences. The rate shall also cover for the

demolition material is to be stockpiled within 1 km of the demolition site for disposal in accordance

with clause 8.2.9 below.

8.2.9 Transport materials and debris to unspecified sites and dump

All surplus material from the work items described in Clause 5.8 stockpiled in accordance with

8.2.8 above, will be sorted and disposed of as follows:

a) The larger portions of the demolished material will have all protruding rebar or other

embedments cut off and disposed of in accordance with the requirements of the EMP.

b) The large size concrete, cleaned of protruding rebar and embedments as described in a) above,

will be disposed of either:

i) At a designated area, within 2 kms of the stockpile, below the new Full Supply Level of the

dam

or

ii) At an approved Waste disposal facility.

c) The smaller particles of size less than 100mm will be separated out and carted to a licensed

dump site.

Application is in progress for a license to dispose of material as outlined in b) above. Should the

application be unsuccessful, all material will have to be removed from site and the quantity for c)

above will increase proportionally.

The rates tendered for the work will include all costs incurred in sorting, cutting, loading,

transporting and dumping and tip fees necessary for the disposal of the demolished material

stockpiled in terms of 8.2.8 above.



130

PS G CONCRETE (STRUCTURAL)

3. MATERIALS

3.2 CEMENT

3.2.1 Applicable Specifications

Sections of the specifications listed in the Standard Specification have been superseded by new

specifications. The pertinent changes are indicated in the table below. For the superseded sections

of the listed specifications the new specifications will apply:

Description Superseded Code New Code

Cement: OPC, RHC SABS 471 SANS 50197-1

Cement: PBFC SABS 626 SANS 50197-1

Cement: PC15 SABS 831 SANS 50197-1

Cement: GBFS SABS 1491 Part 1 SANS 50197-1

Aggregate SABS 1083 SANS 1083

Drying shrinkage of aggregates SABS method 836 SANS 5836

Drying shrinkage of concrete SABS method 1085 SANS 6085

Aggregate size SABS 1083 SANS 1083

Sulphate content: Aggregates SABS 850 SANS 5850-1

Drilling cores SABS 865 SANS5865

Evaluate cores SABS 0100 Part ii SANS10100 Part 2

Load tests SABS 0100 Part ii SANS10100 Part 2

3.2.2 Alternative Types of Cement


The blending of fillers (slag and fuel ash) on site will not be allowed unless written approval is

obtained from the engineer.

3.2.3 Storage of Cement


All cement on the Works shall be fresh and of the best quality and cement which has been

damaged in any way or which has been stored on site for a period exceeding six weeks shall be

condemned and removed from site.

All cement should come from one approved manufacturing source. Cement cannot be supplied

from any different source without the prior approval of the Engineer.

3.4 AGGREGATES

3.4.2 Plums

The use of plums will not be allowed in reinforced concrete.

New item:

3.4.4 Supply of Aggregates


New item:

3.9 ALKALI-SILICA REACTION

The Contractor is to ensure that the aggregates will not have a detrimental effect on the concrete

used on Site and all aggregate must comply with the requirements of SANS 1083. Certificates

stating the alkali content of each delivery of cement to Site shall be supplied by the Contractor.

4. PLANT

4.5 FORMWORK

4.5.3 Ties




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The bolt/feral holes shall be placed with regularity and precision and the tie irons must be removed

and calked completely in the case of water retaining areas.

5. CONSTRUCTION

5.1 REINFORCEMENT

5.1.3 Cover


Fixing/Cover blocks for the attachment of fixtures may be embedded in concrete provided that the

strength is equivalent to the concrete mix being used and any other desirable feature (such as

appearance of the member) is not, in the opinion of the Engineer, impaired thereby.

The contractor must ensure the correct cover as specified is obtained.

5.2 FORMWORK

5.2.1 Classification of Finishes

Replace sub-clause 5.2.1 c) with the following:

c) Special. No special finishes

5.2.5 Removal of Formwork

New item:

5.2.5.6 The use of ‘low heat of hydration’ cements and/or fillers may require special consideration in the

stripping of the formwork and table 2 of SABS 1200G may not be applicable. The Contractor shall

provide a method statement for the removal of formwork prior to placing concrete containing such

cements and/or fillers.

5.5 CONCRETE

5.5.1 Quality

5.5.1.4 Chloride content

The maximum chloride content will be as specified in column 5 of Table 4 for reinforced concrete

exposed to marine environment

5.5.1.5 Durability

The water cement ration will be as per column 5 in Table 5 for moderate section; retaining walls,

piers, beams and exterior portions of mass concrete.

5.5.1.7 Strength Concrete.


The concrete mixes shall be designed for vibration, heat of hydration, shrinkage and expansion

characteristics and the Contractor must demonstrate that the concrete mix design has adequately

addressed these issues.

Surface Bed strength concrete design requires concrete to achieve a minimum concrete strength in

72 hours and a minimum Modulus Ratio at 28 days.

5.5.3 Mixing

5.5.3.2 Ready mix concrete


Should the Contractor propose the use of ready-mixed concrete, a motivation detailing with the

reliability of supply and travel time of the delivery trucks from the supplier’s yard to the Site must be

submitted for approval by the Engineer.



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5.5.7 Construction Joints

5.5.7.1 Replace items b) of sub-clause 5.5.7.1 with the following:

Construction joints are to coincide with contraction joints. The contractor must provide a method

statement prior to casting critical elements that includes the following information:

Casting sequences proposed.

Times between major pours.

Volumes of concrete to be poured.

Curing equipment to be used.

Supply of materials.

Means of ensuring that joints are water proof

5.5.7.4 Construction Joint between the Existing Concrete and New Concrete

In addition to the requirements of clause 5.5.7.3c the rate tendered shall allow for the following:

a) Insitu concrete surface is to be scabbled thoroughly to expose uncontaminated concrete

aggregate.

b) The scabbled surface is to be brushed with a wire brush to remove any loose aggregate.

c) The surface is to be thoroughly soaked for 24 hours before pouring of concrete.

d) The mortar applied immediately before placement of concrete must be treated with an approved

latex bonding agent used in accordance with the manufacturers requirements.

5.5.8 Curing and Protection

e) Curing compound shall be a must white resin based compound containing no water and

complying with ASTM C 309 and applied immediately after placing the concrete.

5.5.8.1 PKW Concrete

Replace items a) to e) of subclause 5.5.8 with the following:

The contractor will be required to supply, erect and maintain an approved fog spray irrigation

system to cover the whole structure. The system must have the facility to run on an automatic timer

and be able to provide the correct curing over a 24 hour period.

The system will be required during all the casting stages and must be maintained for a minimum

curing period of 14 days.

The contractor will only be permitted to place concrete once the system is functioning to the

approval of the Engineer.

5.5.11 Watertight Concrete


The ‘Piano Key Weirs’ are to be considered as water retaining structures and the Contractor will be

responsible for ensuring water tightness in accordance with the requirement of the specification.

Appropriate specifications in DWS 0750: Water Retaining Concrete will also apply.

The works will not be certified complete until the units have been proved by testing to be watertight.

The structure will be considered water tight if there are no leaks or white carbonation marks on the

downstream surface of the structure.

5.5.13 Grouting


Where grouting in of rebar dowels is specified on the drawings the following additional

requirements shall apply:



133

All dowels shall be installed in holes drilled into existing concrete structures in

accordance with the details shown on the drawings and secured by means of the

specified.

The holes should be 1.3 times larger than the prescribed fixing bar detailed for

optimum bonding or as prescribed by the epoxy / adhesive manufacturers

specifications.

The hole is to be cleaned thoroughly of dust and loose aggregate using

compressed air followed by water jetting or in accordance with the adhesive being

used.

The dowel bars must be fixed solid before concrete is cast. They will be tested by

the engineer prior to casting.

The contractor must allow in his tendered rate all wastage, health requirements,

machinery and materials required to mix the epoxy grout to manufacturer’s

requirements.

New Clause

5.5.16 Water Proofing of Joints

All joints formed in the PKW, whether indicated on the drawings or whether agreed to in terms of

the concrete placement method statement, must be water proof and the contractor is to supply

samples of all proposed sealers along with the relevant manufacturer’s details for approval.

Where water proofing by application of special measures is specified on the drawings such as in

the case of the installation of water bar for the expansion joints or where deemed prudent by the

Contractor as a necessary precaution and agreed to by the Engineer, the following will apply:

a) Use of water bar

The water bar must comply with the specifications of DWS 1810 in Volume 3 of this document.

The construction joints (or contraction joints) are shown on our drawings. These joints are

important with respect to the shrinkage of the concrete after casting. The final jointing drawings

with respect to water stops and construction procedures by the contractor must be produced by the

contractor for approval by the engineer. The technical support for the final jointing arrangements

must take into account the concrete design mix proposed, water stop supplier specifications,

standard details, jointing details and technical advice.

The water bar selected must take into consideration the existing water bar in the structure as it

must be bonded to the existing water bar in order to ensure continuous water proofing.

b) Swell-able Water-stops

The use of a swell-able water stop for providing an integral seal between new and old concrete will

be permitted in certain instances where waterproofing by this method is deemed to be appropriate

and as approved by the Engineer. In such applications the manufacturer’s specifications must be

strictly adhered to by the Contractor.

6. TOLERANCES

6.2 PERMISSIBLE DEVIATIONS

6.2.3 Append sub-clause 6.2.3 with the following:



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Levels to top of PKW walls

The top of the end wall of the central inlet key shall be finished to an accuracy of 1mm in 3m of

length and 1mm tolerance with respect to the level specified. All other top levels must be finished to

Degree of Accuracy II but with no negative tolerance.

7. TESTS

7.1 FACILITIES AND FREQUENCY OF TESTS

7.1.2 Frequency of Sampling

7.1.2.2 Replace sub-clause 7.1.2.2 with the following:

At least two sets of samples shall be taken from each day’s casting and from at least every 50m3

of concrete of each grade placed.

The Contractor shall take additional sets of samples, at his own cost, to verify the concrete

strengths for stressing and formwork stripping of concrete pours for critical elements.


8.4.3 Strength Concrete

a) 40/19 concrete to PKW

The rate must allow for the concrete to comply in all respects with best practice for water retaining

structures, the joint to be treated as specified in clause 5.5.7.4 above and for curing to be done in

accordance with 5.5.8.1 above.

b) 30/19 concrete to Emergency spillway topping slab

The rate must allow for the concrete to comply in all respects with best practice for thin slabs. The

joint between the old and new concrete must be treated as described in 5.5.7.4 above and the

curing must be carried out as specified in 5.5.8e of SANS 1200 G

8.5 JOINTS

Append clause 8.5 with the following

As appropriate the rates tendered will also cover the cost of complying with clauses 5.7, 5.8, 5.11

and 5.16 above.

Where cutting of joints is specified these joints are to be cut as soon as the concrete surface will

permit cutting and the rate will cover the cost of supply, delivery, use and operation of any plant

required, in addition to all other costs incurred for forming the joint.

8.6 MANUFACTURE AND PLACE PRECAST ELEMENTS

Append to Clause 8.6

The rate shall also cover the cost of securing in place and casting into the concrete any anchor

embedment items required (Cost of the embedment item to be included in the supply of the Rock

Anchor under Section GG) as well as the supply and casting in of the structural steel frame and lid

to be provided in accordance with the Drawings.

8.7 GROUTING

In addition to the provisions of Clause 8.7b in the standard Specifications the rate shall allow for the

additional provisions of 5.5.13 above.



135

PS HA STRUCTURAL STEELWORK (SUNDRY ITEMS)


8.3 SCHEDULED ITEMS

8.3.6 Replace sub-clause 8.3.6 with the following:

Corrosion Protection

The Rates for all items under Pay Reference 8.3 will include for Heavy Duty Hot Dipped

Galvanizing Corrosion Protection in accordance with the relevant clauses of the DWS 9900 C6

Specification, included in Volume 3 of this document.



136

PS L PIPELINES

3. Materials

3.4 Steel Pipes, fittings and specials

3.4.3 Pipes of nominal bars over 150mm

Append to Clause 3.4.3

The provisions of specification DWS 1110: Construction of Pipelines will also apply.

The provisions of specification DWS 2510: Supply of Valves will also apply.

3.9 Corrosion protection

3.9.1 Steel Pipes

3.9.2.2 Steel Pipes of nominal bore over 150mm

Append to Clause 3.9.2.2

The provisions of specification DWS 9900: Corrosion Protection of Steel Pipes and Specials for

Pipelines will also apply.

8. Measurement and Payment

8.1 General

8.2 Scheduled Items

8.2.5 The rates tendered for items E1.1 a; b; c; d and e in the Bill of Quantities shall also allow for work to

be performed in accordance with the drawings and with clauses 3.4 and 3.9 above.

The rate tendered for item d) will allow for the supply of gate valves that comply in all respects with

DWS 2510 Supply of Valves - Particular Valve Specification – Gate Valves, included in Volume 3.



137

C.3.3.2 Additions and Amendments to Standard Specifications Other Than SANS 1200

PS B1 Rock Anchor Specification

General introduction

The specification applies to the supply, installation, stressing and testing of 379 No. post-tensioned anchors

with a working load of 3400 kN.

The anchors are to be generally fabricated, installed, stressed and tested in accordance with BS8081:1989

Ground Anchorages. However, the purpose of this section of the document is to highlight project specific

aspects which shall be implemented by the specialist anchor contractor.

Definitions

Definitions are as defined in Section 2 of BS8081:1989. However, the term anchorage(s) will be referred to

as anchor(s) within this document.

4. RESPONSIBILITIES

Table 1. Recommended design and construction duties

Consultant Contractor

(1) Site investigation data for ground anchorages (1) Anchorage components and details

(borings near fixed anchor locations and outside the (2) Determination of fixed anchor dimensions

site working area if necessary). (3) Meet the requirements of Anchorage

(2) Decision to use ground anchorages, required trials spacing/orientation free anchor length and

and testing and provision of a specification anchorage loads

(3) Overall design of anchored structure, calculations (4) Detailing and performance of the corrosion

of anchorage force required. Definition of safety protection system for anchorage

factors to be employed. (5) Supply and installation of anchorage monitoring

(4) Definition of anchorage life and requirements for system

corrosion protection. (6) Quality control of works

(5) Anchorage spacing and orientation. Free anchor (7) Anchorage maintenance as directed by the designer

length and anchorage load.

(6) Anchorage behaviour monitoring system,

(structure/anchorages) and interpretation of results.

(7) Supervision of the works (inspection by testing and

sampling).

(8) Maintenance specification for anchorages.

(9) Instruction of all contracting parties of key items

within design philosophy to which special attention

should be directed.

In the event of the proving test anchors failing, the Client will not be held liable for costs incurred relating to the

delays while the Contractor redesigns the anchorage system and installs proving test anchors that do pass the

proving tests.



138

6. DESIGN

6.1 GENERAL

Suitable safety factors are listed in Table 2 under the Anchorage Category of Permanent

Anchorages.

6.2 GROUND/GROUT INTERFACE

All anchorages are subject to a testing procedure as detailed in clause 11. Proving tests shall be

carried out to determine ultimate load holding capacity

8. CORROSION AND CORROSION PROTECTION

8.2 CORROSION PROTECTION

Due to permanent anchorages being installed and a maximum design life of the anchorages

warranted, a minimum of double corrosion protection is required on all anchorages.

Double protection implies the supply of two barriers where the purpose of the outer second barrier

is to protect the inner barrier against the possibility of damage during tendon handling and

placement. The second barrier therefore provides additional insurance, given the distinction

between the degree of protection of the tendon once installed in the ground, and that of the tendon

as supplied.

At the anchor head location, components cannot be wholly prefabricated. Because of the strain in

the tendon associated with prestressing, friction grips for strand and locking nuts on bars cannot fix

the tendon until extension has been achieved.

All existing locking arrangements require bare strand on which to grip and any preformed corrosion

protection of the tendon has to be removed. This leaves two sections of the tendon, above and

below the bearing plate, which require separate protective measures in addition to the protection of

the bearing plate itself.

10. CONSTRUCTION

10.2.4 Hole Geometry

The overall alignment and deviation should not exceed 1:300.

10.4 GROUTING

Provide for all grouting operations to be carried out under the personal direction of one or more

skilled supervisors experienced in similar work. The Designer may direct cessation of grouting at

any time when such supervision is not provided. It is desirable that the supervisor is experienced in

the successful handling of grout mixes with a W/C ratio of about 0.45: I by weight. The Designer will

advise the Contractor of the acceptability, or otherwise of his supervisor(s).

10.4.2 Borehole Testing

On completion of grouting it is necessary to ensure that the loss of grout over the fixed anchor

length is insignificant. This can be achieved by the use of tremie pressure injection techniques

during routine grouting of the anchor or alternatively by pre-testing for and/or providing a grout-tight

borehole over the fixed anchor length.

11. TESTING

11.2 PROVING TESTS

Proving tests will be required to demonstrate or investigate, in advance of the installation of working

anchors, the quality and adequacy of the design in relation to ground conditions and materials used

and the levels of safety that the design provides. The tests may be more rigorous than on-site

suitability tests and the results, therefore, cannot always be directly compared, e.g. where short

fixed anchors of different lengths are installed and tested, ideally to failure. In such cases where the



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ground capacity is being investigated, loads are quoted in terms of characteristic strength of tendon

and the appropriate working load is deduced from the proving test results.

7 No. proving tests shall be carried out on site, in order to demonstrate the suitability of the

materials, components, methods of construction, workmanship and to establish the ultimate in situ

bond stress that can be mobilised in the vicinity of the fixed anchor zones.

1 no. through the spillway crest

1 no. through the emergency spillway crest

1 no. through the spillway downstream face

1 no. through the emergency spillway downstream face

3 no. directly into the underlying rock possibly accessed through the downstream side of the dam

On-site suitability tests are carried out on anchors constructed under identical conditions as the

working anchors and loaded in the same way to the same level. These may be carried out in

advance of the main contract or on selected working anchors during the course of construction. The

period of monitoring should be sufficient to ensure that prestress or creep fluctuations stabilize

within tolerable limits. These tests indicate the results that should be obtained from the working

anchors.

At least the first three anchors should be subjected to suitability tests with further tests for each

category of anchors envisaged in the works. Anchors are categorized by the following:

(a) Geometry, e.g. vertical or inclined;

(b) Ground types, e.g. clay, gravel or rock;

(c) Load capacity.

11.3.2 Proof Loads

The maximum proof load should be 150%Tw for permanent anchorages, where Tw is the working

load of the anchorage.

The maximum proof load shall be 80% of the characteristic strength of the tendon in proving tests

and 150% working load for permanent production anchors.

INFORMATION REQUIRED

The specialist anchor contractor shall provide a Method Statement giving details of the post-

tensioned anchors that are intended to be supplied and installed. Include details of clearances

required around anchor assemblies, grout tube size, experience with and achievability of the

specified grout mix and W/C ratio, details and dimensions of the proposed sheathings and the

tendon installation procedures. Note and outline any necessary changes to concrete and

reinforcement drawings. Provide details of the epoxy mortar for supporting the bearing plates.

Provide details of anchors head for approval. Supply design calculations and all other details

considered necessary by the Designer within 2 weeks of the award of the Contract. Acceptance of

the Method Statement by the Designer is a prerequisite to the start of the works. The Contractor is

also to provide their intended plans for substantial Quality Assurance and Quality Control within 2

weeks of the award of the Contract.

APPROVAL REQUIRED

Unless otherwise advised by the Designer, do not commence fabrication of the cables until

acceptance by the Designer of the Contractor's design calculations and all other important details

are obtained.

LOAD MONITORING



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The DWA will monitor the performance of the anchors on completion of the Contract by periodically

measuring the loads in the anchors. The Contractor shall supply and install suitable load cells (or a

similar approved monitoring system) and associated equipment for this purpose which shall

comprise portable monitoring equipment for periodically checking the loads in selected anchors.

Load monitoring shall consist of a hydraulic pressure transducer load cell and other associated

equipment (or a similar approved monitoring system). The dimensions of the load cell shall be such

that it can be readily and easily moved to the anchor head location and can be accommodated in

the space around all post-tensioning anchor head assembly. The Contractor shall supply the load

cell complete with all necessary adaptor rings and saddles. Submission of details of proposals for

the load monitoring and transport system shall accompany the Tender submission.

The load cell and anchor head assembly so required to be supplied shall enable adjustment of the

anchor head level so that the tendon may be re-stressed by a minimum of 5% of MBL following

completion of the anchor head installation, stressing and trimming of excess strand. The anchor

head assembly arrangement shall provide for re-stressability of individual strands.

Equipment so required to be supplied shall measure the load in the cables to an accuracy of ± 2%

of the actual load. Demonstrate to the satisfaction of the Designer, on an anchor nominated by the

Designer, that the equipment is capable of measuring load to the required accuracy.

12 MEASUREMENT AND PAYMENT

12.1 GENERAL

The rates and pricing assume anchor types and forces as specified in the Drawings and Project

Specifications. The Contractor is at liberty to provide alternative design and stability anchor types

provided that all tests are performed as specified in clause 11 above and the loads specified are

provided in the equivalent position and inclination specified on the drawings.

12.2 SCHEDULED ITEMS

12.2.1 Drilling of 275mm diameter holes for Rock Anchors:

12.2.1.1 Set up at each position

The rate will cover for the design, erection and removal of all scaffolding and support work

necessary to create a platform capable of supporting the drilling rig in position to drill the hole,

crane requirements to place the rig on the platform and remove it afterwards, accurate positioning

of the drill rig and setting up of direction and inclination in order to drill the anchor hole in the

position indicated on the drawings and to the tolerance required..

12.2.1.2 Drilling of holes

The rate will cover drilling operations to drill the hole within the specified tolerances, water testing,

grouting and re-drilling as necessary, until the hole is to the correct depth and tolerance and water

loss under water test is within the specification.

12.2.2 Manufacture and assembly of 3.4 MN Rock Anchors

12.2.2.1 Anchor Heads

The rate will cover for the manufacture, supply and assembly of all components, including the

necessary supply of storage sheds and assembly beds and covering as required.

12.2.2.2 Strand, sheathing, corrosion protection etc for the free length

The rate will cover for the manufacture and supply of strand, fittings, corrosion protection materials

and sheathing, storage and handling on site, measuring and cutting of strand and assembly of all

components including corrosion protection, supply of assembly beds and covering as necessary.

12.2.2.3 Strand, etc, for fixed length

The rate will cover for the manufacture and supply of strand and fittings, storage and handling on

site, measuring and cutting of strand and assembly of all components including corrosion

protection, supply of assembly beds and covering as necessary per anchor.



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12.2.3 Transport and install 3.4 MN Rock Anchors

The rate will cover the supply and use of all equipment and plant required to transport the Rock

Anchors from the assembly beds to the position in which the anchor is required as well as inserting

the anchor into the hole already prepared.

12.2.4 Grouting in of fixed length


necessary to create a platform capable of supporting the plant and equipment required to perform

the grouting operations, all pipework and fittings to connect to the grout pipe in the anchor

assembly, supply and mixing of grout, pumping of grout, all as required, as well as crane

requirements to place the equipment on the working platform and to remove it afterwards.

12.2.5 Tensioning of Rock Anchors


necessary to create a platform capable of supporting the plant and equipment required to perform

the tensioning operations, the supply and operation of the tensioning plant and equipment, the

tensioning and locking off of anchors as required, as well as crane requirements to place the

equipment on the working platform and to remove it afterwards.

12.2.6 Corrosion Protection of Anchor Heads

The rate will cover the supply and application of all corrosion protection methods as specified in

terms of Clause 8 of BS 8081.

12.2.7 Testing of Rock Anchors

The rate will cover the coring of holes, assembly, installation and tensioning of Rock Anchors all as

described in 12.2 1 to 12.2.6 above inclusive of additional tensioning of anchors to test load as

specified in Clauses 10 and 11 of BS 8081 The rate will also cover the cost of making good

afterwards.

12.2.8 Monitoring of Anchors

As indicated in clause C.3.2.2 (d) above, the monitoring of the rock anchors is important throughout

the life of the anchors. The following items are included in the Bill of Quantities (BOQ) to allow for

this process on the basis of either monitoring a sample of anchors and all inaccessible anchors,

OR monitoring all anchors.

12.2.8.1 Anchors

a) The rate will cover the cost of supply, assembly and installation of the measuring and monitoring

equipment for each anchor.

b) The rate will cover the cost of supply, assembly and installation of the measuring and monitoring

equipment for each anchor in the event that it is decided to limit monitoring to a sample of

approximately 100 anchors.

12.2.8.2 Network

a) The rate will cover the cost of supply and installation of all hardware and software required to

provide a continual data record of the load in all the anchors for the lifetime of the anchors. Should

the proposed network be a wireless network, then the trenching in BOQ item B.1.2.8 will not be

required. Should a wired monitoring system be proposed, then the rate will include for the provision

and embedment of all ducting, wiring etc. in the trenches provided.

b) As for a) above in the event that monitoring is limited to a sample of 100 anchors.



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C.3.3.3 Other Particular Specifications

PARTICULAR SPECIFICATION B2: DRILLING 1. SCOPE ......................................................................................................................................... 143 2. DEFINITIONS ............................................................................................................................... 143 3. MATERIALS ................................................................................................................................. 143 3.1 General ........................................................................................................................................ 143 3.2 Water ............................................................................................................................................ 143 3.3 Drilling Fluid ................................................................................................................................ 143 3.4 Core Boxes .................................................................................................................................. 143 3.5 Casing Materials ......................................................................................................................... 144 3.5.1 General ........................................................................................................................................ 144 3.5.2 Core Holes ................................................................................................................................... 144 3.5.3 Drainage Holes ............................................................................................................................ 144 3.5.4 Grout Holes ................................................................................................................................. 144 4 PLANT .......................................................................................................................................... 144 4.1 General ......................................................................................................................................... 144 4.2 Rotary Core Drilling Equipment ................................................................................................. 144 4.3 Rotary Percussion (top hammer) Drilling Equipment .............................................................. 144 4.4 Rotary Percussion (bottom hammer) Drilling Equipment ........................................................ 145 5 CONSTRUCTION ......................................................................................................................... 145 5.1 General ......................................................................................................................................... 145 5.2 Drilling Rotary Core Holes .......................................................................................................... 145 5.3 Drilling Grout Holes .................................................................................................................... 145 5.4 Drilling Drainage Holes ............................................................................................................... 146 5.5 Drilling Holes through Concrete ................................................................................................ 146 5.6 Drilling Instrumentation Holes ................................................................................................... 147 5.7 Drilling Holes for Rock Dowels, Rock Bolts and Rock Anchors ............................................. 147 5.8 Storage of Cores ......................................................................................................................... 147 5.9 Handling of Cores ....................................................................................................................... 147 5.10 Marking Exploratory Holes ......................................................................................................... 147 5.11 Plugging of Holes ........................................................................................................................ 147 5.12 Drilling Records .......................................................................................................................... 148 6 TOLERANCES ............................................................................................................................. 148 6.1 General ......................................................................................................................................... 148 7 TESTING ...................................................................................................................................... 148 7.1 Standard Penetration Test ......................................................................................................... 148 8 MEASUREMENT AND PAYMENT .............................................................................................. 149 8.1 General Principles ....................................................................................................................... 149 8.1.1 Rotary Core Drilling .................................................................................................................... 150 8.2 Scheduled Items ......................................................................................................................... 150 8.2.1 Setting up over Holes ................................................................................................................. 150 8.2.2 Drilling .......................................................................................................................................... 150 8.3 Scheduled Items ......................................................................................................................... 151 8.4 Casing .......................................................................................................................................... 151 8.5 Core recovery ............................................................................................................................. 151 8.6 Core boxes .................................................................................................................................. 151 8.7 Standpipes for grout holes ........................................................................................................ 152 8.8 Grouting of holes for stabilization ............................................................................................ 152 8.9 Plugging of holes ....................................................................................................................... 152 8.10 Marking of exploratory holes .................................................................................................... 152 8.11 Standard Penetration Test (SPT) .............................................................................................. 152 8.12 Standby........................................................................................................................................ 152 FIGURES Figure 11.1 : Details of Core Box 125 Figure 11.2 : Labelling of Core Box 126



143

1. SCOPE

This specification deals with the drilling of holes for grouting, drainage, instrumentation and rock

support by means of rotary percussion methods and holes for geotechnical exploration by

means of rotary core methods.

The maintenance of accurate drilling records and the disposal of waste, the cleaning up of the

areas upon completion of the work and all other operations that are incidental to performing the

above operation also fall within the scope of this specification.

2. DEFINITIONS

The following definitions shall apply:

“Confined hole” : A hole drilled in any required direction above or below horizontal where an

immovable obstruction such as a wall or rock face would prevent a straight rod of 2,5m length

being inserted into the hole.

“Drainage hole” : A drainage or pressure relief hole is a hole required to relieve hydrostatic

pressure in the rock mass or concrete. It may be drilled from the surface or from a gallery,

through concrete or through a pipe embedded in the concrete for this purpose.

“Exploratory hole” : A hole drilled to obtain information about the ground conditions either by

recovering a cored sample of as much of the material drilled that is feasible and/or to only

recover drill cuttings and to provide access for the purpose of testing.

“Grout hole” : A hole drilled for the purpose of injecting grout into the ground.

“Instrumentation hole” : A hole drilled for the purpose of placing instruments in the structure, soil

or rock.

“Well-screened hole” : A hole, usually of large diameter drilled in soil or unconsolidated gravels

or boulders to be developed with filter gravel and a screened inner casing.

3. MATERIALS 3.1 General

Subject to the Engineer's approval of materials used, the Contractor shall make his own

arrangements for any materials required for the satisfactory completion of the work.

3.2 Water

Water used for drilling shall be clean and free from injurious amounts of acids, alkalis, suspended clay and other substances, which may have a detrimental influence on drilling performance or on the subsequent behaviour of the drilled hole when being tested for water loss or when being grouted.

3.3 Drilling Fluid

Drilling fluid shall only be used where previously agreed to by the Engineer and shall be such that it does not change the properties of the rock or soil or seal the inner wall of the hole. Bentonite and other similar drilling muds shall not be used.

3.4 Core Boxes

All core recovered from all boreholes shall be retained and carefully, neatly and securely packed in the correct sequence in approved core boxes, the design of which is given in Figure 11.1, so as to produce reliable record of the formation drilled. No core box shall contain core of more than one hole. The borehole number, depths of core and the box number shall be marked clearly, neatly and indelibly on boxes as specified in Figure 11A.2.



144

Core boxes shall be of robust wooden construction to withstand the weight of core and any full boxes which may subsequently be placed upon them and also sufficiently watertight to protect the core from rain on Site or in transit. They shall be made to hold the particular size of core tightly in place in rows separated by securely fitted partitions. Core box lids shall be kept securely fastened to the boxes at all times except when inspected. A sample core box shall be submitted to the Engineer for acceptance prior to manufacture or placing of orders.

3.5 Casing Materials

3.5.1 General

All metal and uPVC pipes and fittings required for casings and standpipes shall be of the size matching the particular size of hole being drilled and shall be furnished, cut, threaded, fabricated and embedded by the Contractor.

3.5.2 Core Holes

Casings to support the sides of holes in caving ground shall be mild steel flush screw jointed tubes conforming to BS1387.

3.5.3 Drainage Holes

Casings to support the sides of holes in caving material shall be steel conforming to BS 1387 or uPVC conforming to SANS 966 and shall be Class 6.

3.5.4 Grout Holes

The casings required for grout holes shall be steel, conforming to BS 1387 or uPVC conforming to SANS 966 and shall be Class 6.

4 PLANT

4.1 General

All equipment shall be of the most modern type in good mechanical condition with adequate capacity and suitable for doing the work. Full details of all drilling equipment shall be submitted to the Engineer for approval before starting any drilling operation.

The Contractor shall provide and maintain all drilling machines and equipment needed for drilling the holes to the sizes and depths shown on the Drawings, in the Schedule of Quantities or in the Specifications.

The Contractor shall provide equipment capable of measuring the slope and direction of holes accurately to within 1 degree.

All drilling equipment shall be capable of drilling holes in compliance with the tolerances set out in Clause 11A.6 of this specification.

4.2 Rotary Core Drilling Equipment

Rotary core drills and associated equipment shall be capable of producing N and H size core from holes drilled in any direction and drilling 150mm diameter cored holes in concrete in any direction. Drills shall be equipped with hydraulic feed control and double tube core barrels. The equipment shall be capable of drilling and recovering core to a depth of 70m. Drilling equipment shall also be available to drill from a gallery with size 2,5m wide by 3m high.

4.3 Rotary Percussion (top hammer) Drilling Equipment

Rotary percussion type drills, using compressed air fed down hollow drill rods for the removal of

drill cuttings shall generally be used for drilling holes from 38mm diameter up to 100mm

diameter. The drills shall be capable of drilling holes at any angle to depths of 60m. Drilling

equipment shall also be available to drill from a gallery with size 2,5m wide by 3m high.



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4.4 Rotary Percussion (bottom hammer) Drilling Equipment

Not applicable.

5 CONSTRUCTION

5.1 General

Drilling, sampling and testing shall be performed in a workmanlike manner and only by

competent and experienced workmen. The Contractor shall submit details of the qualifications

and experience of the supervisors and operators he proposes to use to the Engineer for

approval before starting any drilling operation.

The Contractor shall ensure that no pollution of the Site or defacement of structures occurs as a

result of drilling operations.

The positions, directions, depths, sizes and inclinations of holes and the type of drilling equipment to be used shall be as indicated in these specifications, on the Drawings or as

directed by the Engineer. The Contractor shall set out all holes to be drilled.

All holes shall be drilled straight without deflection in the directions and at the inclinations

indicated.

Due allowance shall be made by the Contractor for interrupting the drilling to flush or pressure

wash the boreholes and to perform water pressure tests as specified in Section 11B, to survey

the boreholes if required in terms of the Contract or to rinse, flush or grout sections of boreholes

as specified in Section 11C.

5.2 Drilling Rotary Core Holes

Rotary core drilling may be required for grout holes, piezometers, exploratory work and for RCC

quality testing. Rotary core drilling shall only be performed as directed by the Engineer. The hole

size shall normally be N size (76mm diameter) for grouting and exploratory work, but may be

larger for piezometer installation (100mm diameter) and 150mm for RCC coring. Continuous

core recovery shall be obtained whenever possible in both hard and soft material.

5.3 Drilling Grout Holes

All holes for grouting shall be drilled by rotary percussion drilling methods in the sequence and

at the locations, in the directions, at the inclinations and to the depths and diameters shown on

the Drawings or ordered by the Engineer. Standpipes, nipples or casings set in the concrete or

rock shall generally only be required for grout holes in fractured and/or weak rock, where

surface water or debris can enter the top of the hole or as shown on the Drawings or instructed

by the Engineer.

Grout holes shall be drilled in stages conforming to the specified grouting stages using the split

spacing method. The spacing of the primary holes will depend on conditions encountered and

shall be as indicated on the Drawings or as directed by the Engineer, but in general they shall

be spaced at a distance of 8m for curtain grout holes. Sequential holes shall only be drilled at

the instruction of the Engineer.

The Contractor shall ensure that drill bits used to drill grout holes are in good order so that

excessive wear of bits will not cause wedging if at any time a hole has to be deepened.

Each hole drilled shall be protected from becoming clogged or obstructed by means of a screw

cap on the standpipe or other suitable device. Any hole that becomes clogged or obstructed

before completion of grouting shall be cleaned out in a manner to the satisfaction of the Engineer or another hole provided.



146

Whenever drill water is lost, or artesian flow is encountered, the drilling operation shall be

stopped and the hole cleaned, pressure tested and grouted in accordance with the relevant

specification and to the instructions of the Engineer before drilling operations are resumed. The

grout so remaining in a partially completed hole shall be removed therefrom by flushing or other

methods before it has set sufficiently to require redrilling.

Where casings are used when drilling in caving ground such casings shall be supplied and installed by the Contractor in such a manner that easy removal of the casings is facilitated. All

casings shall be cleaned thoroughly of all dirt, grease or oil before embedment.

In situations where it proves impossible to install casings in caving ground with conventional

methods due to collapsing of the hole, the Contractor shall, with the approval of the Engineer,

use specialized drilling methods whereby the casing proceeds concurrently with drilling, such as

the "ODEX" method.

Where drilling through concrete placed in the Works is required, the Contractor may substitute

pipes of the appropriate diameter in lieu of such drilling, subject to the approval of the Engineer.

Where required by the Engineer and where conditions dictate, grout holes shall be provided with standpipes at the head of the hole. They shall project approximately 150mm above the rock or

concrete surface and shall be bonded firmly into the surface for a length of not less than

500mm. The bore of the standpipe shall be adequate to accommodate the size of drill bits

required.

All standpipes shall be cleaned thoroughly of all dirt, grease, grout and mortar before being

embedded in the concrete or rock.

The Engineer may order the drilling of a check hole(s) to determine the effectiveness of a

grouted section. Such a check hole shall be drilled as for a grout hole, but comprehensive water

pressure tests shall be performed according to Section 11B.

5.4 Drilling Drainage Holes

Unless otherwise directed, drainage holes shall be drilled by percussion drilling and flushed

clean. The holes shall be drilled to the diameter and in the direction, inclination and location as

indicated in the Drawings or directed by the Engineer.

Drainage holes shall not be drilled until all grouting required within the vicinity has been

completed to the satisfaction of the Engineer.

Drainage holes through concrete and rock shall be lined with an approved slotted PVC sleeve

where shown on the Drawings or directed by the Engineer.

5.5 Drilling Holes through Concrete

Where holes are required through concrete, the Contractor will be permitted to either drill the

holes or where indicated on Drawings or as instructed by the Engineer embed PVC sleeves in

the concrete through which the rock behind or below the concrete can be reached.

No drilling shall be allowed in concrete less than 7 days old.

In the case of reinforced linings, the formwork shall be marked by means of plugs or in some

other way approved by the Engineer to indicate positions where drilling may be carried out

without obstruction by reinforcement.

Should steel reinforcement be encountered during the drilling of any hole into concrete, where

required by the Engineer, drilling shall be discontinued immediately and a new hole shall be

drilled alongside. Such discontinued holes shall be plugged as specified in Section 11C.5.3.1(j).

Sleeves left in the concrete, but which have not been used for drilling holes shall also be

plugged.



147

Holes of 150mm diameter in RCC as ordered by the Engineer shall also fulfil the requirements

of Section 6, Sub-clause 6.9.1.2 – RCC Coring Programme. 5.6 Drilling Instrumentation Holes

Unless otherwise directed, instrumentation holes shall be drilled by percussion drilling and

flushed clean. The holes shall be drilled to the diameter and in the direction, inclination and

location as indicated on the Drawings or directed by the Engineer.

Instrumentation holes shall not be drilled until all grouting required within 10m from the hole has

been completed to the satisfaction of the Engineer.

5.7 Drilling Holes for Rock Dowels, Rock Bolts and Rock Anchors

Unless otherwise directed, holes for rock dowels, bolts and anchors shall be drilled by

percussion drilling and flushed clean. The holes shall be drilled to the diameter and in the

direction, inclination and location as indicated on the Drawings or directed by the Engineer.

Water pressure tests shall be performed in such holes as directed by the Engineer.

5.8 Storage of Cores

A suitable storage facility for core boxes shall be provided on Site by the Contractor.

.

5.9 Handling of Cores

The core shall be removed from the core barrel by a method designed to produce minimal

disturbance to the core. Extraction under steady carefully applied pressure, the use of split inner

barrels or other method acceptable to the Engineer shall be used. The cores shall not be

extracted by hammering the barrel or by extrusion under high air or water pressure. Where the

core may be prone to slaking, the core shall be sealed in an appropriate plastic sheath.

Core shall be laid in the boxes in correct sequence clearly marked with wooden spacers, giving

the depth at any points of interest and marking all points of core loss.

5.10 Marking Exploratory Holes

When directed by the Engineer, exploratory holes shall be marked by means of a concrete block

and steel peg. The steel peg shall be of 16mm diameter, extend 50mm above the top of the

concrete block and be 300mm long. The concrete block shall be round with 300mm diameter

and 150mm into the ground surface and not protruding above ground surface.

5.11 Plugging of Holes

All exploratory holes drilled prior to construction and holes drilled during the Contract for

exploratory purposes and not used for any other purpose such as for grout or drainage holes,

shall be plugged, unless otherwise ordered by the Engineer. The Engineer shall identify and/or

locate the holes that need to be plugged and such plugging shall be carried out at an early

stage of the Contract, before the standpipes or identification marks are damaged by

construction activities.

All holes that have become clogged shall be cleared before being plugged. Where necessary

to clear the hole, rotary percussion equipment may need to be employed.

After the removal of standpipes or casings the holes shall be backfilled with a 1:1 mixture (by

volume) of cement and water. In dry holes the grout may be poured in from the top, but if the

hole contains standing water the grout shall be fed through a tremie pipe, the outlet of the

tremie pipe being kept submerged in the grout at all times. If running water is encountered in

the hole, the Engineer shall direct what procedure is to be followed.



148

Grout holes shall be plugged according to Section 11C, Sub-clause 11C.5.3.1(j).

Where the hole, or portion thereof is in a concrete structure, it shall be backfilled with a 1:0,75

grout mixture (by volume) of cement and water upwards from the bottom of the hole so that all

water is replaced by grout.

5.12 Drilling Records

The Contractor shall each day provide the Engineer with an accurate record on forms approved

by the Engineer of all holes drilled on the previous day.

The information provided shall inter alia include the following :

a) The reference number, location of the hole, drilling method and stage of hole (where

applicable).

b) The actual positions of the boreholes recorded to an accuracy of 20mm and the actual

directions and inclinations of the borehole at the borehole collars recorded to within an

accuracy of 1 degree of arc.

c) A non-technical description of all materials encountered, their locations in the holes, the

material recovery for each stratum, changes in the formation (fissures, cavities, seams,

etc.) and any other data which may help in the evaluation of the ground.

d) Size and type of bits used.

e) Levels at which groundwater was encountered and wash-water lost or gained.

f) Drilling pressures and rotation speeds.

g) Any relevant incidents that occurred during the course of the work.

6 TOLERANCES

6.1 General

Unless otherwise indicated on the Drawings or in the Project Specifications, all holes to be

drilled shall be collared to a tolerance of 200mm of the specified position or 25% of the specified

distance between holes, whichever is the lesser. All holes shall be drilled to a tolerance of 3

degrees of the specified inclination and orientation. Where holes are drilled through mass

concrete, such as for grout holes, the holes shall be collared to a tolerance of 50mm of the

specified position and shall be drilled to a tolerance of 3 degrees of the specified inclination and

orientation. Nipples or sleeves set in concrete to act as guides for drilling shall be set in the

concrete to a tolerance of 30mm. The holes shall be drilled to within 0,5m of the specified final

depth.

7 TESTING

7.1 Standard Penetration Test

Standard penetration tests (SPT) shall be carried out in accordance with the international

reference test procedure laid down in the proceedings of the First International Symposium on

Penetration Testing (ISOPT) 1988 except that the number of blows for each 75mm of the total

450mm penetration shall be recorded. Prior to any SPT’s being carried out, the engineer shall

inspect and approve the equipment to be used.



149

Before commencing the test, the borehole shall be cleaned to the depth where the testing is to

be done. Care must be taken to prevent disturbance of the material to be sampled. The washing

out of the hole by means of side discharge bits is allowable, but not by means of washing

through an open tube. Care shall be taken to ensure that the borehole is cleaned right to the

bottom of the hole in all circumstances. Where casings are used, the bottom end of the casing

shall be no closer than 150mm to the level where the tests are commenced.

When drilling in sand or silt below the water table, the water level in the casing shall always be

kept higher than the ground water level, so that sand and silt is kept from flowing into the

borehole. A valid SPT cannot be executed where an influx of sand or silt has occurred, since

such influx disturbs the materials under the base height of the casing, as well as causing greater

friction against the sample tube. When boring under the said conditions, water shall be

continuously added in order to maintain the water level in the casing level with the top of the

casing. Steady water supply is extremely important during the removal of the drilling rods since

removal is accompanied by a drop in level of the water in the hole. The rods must be removed

slowly and gradually.

Samples recovered from the split barrel sampler shall be sealed in an approved, airtight,

transparent container and placed in the core box at the relevant depth and the blow counts

written onto the sample container.

When it becomes evident that the SPT tests cannot be performed with the standard split barrel

sampler due to gravel or pebble layers, the driving shoe and the standard split barrel sampler

shall be replaced with a 60° cone-end shoe and a normal tube barrel, the overall dimensions of

which correspond to that of the standard split barrel sampler. The outside diameter of the cone-

end shoe shall be 51mm and the total length from tip to base shall be 56mm.

The test with the cone-end shoe shall in all other respects be executed in accordance with

ISOPT standards except that the number of blows for each 75mm of the total 450mm

penetration shall be recorded.

Care shall be taken to ensure that the energy of the hammer is not reduced by friction between

hammer and wall or by any other cause. “Refusal” of the SPT is defined as when the number of

blows necessary to penetrate 75mm exceeds 25. If refusal occurs, the blow counts recorded till

refusal and the actual penetration in mm for the last (refusal) cycle shall be recorded.

8 MEASUREMENT AND PAYMENT

8.1 General Principles

Specific items such as drilling and casings will be measured by length and classified by size,

making provision for various ground conditions. With the exception of casing, payment for

materials used shall be limited to those installed in the Permanent Works, which shall be

classified according to their nature and usage. Measuring of water levels as required from time

to time shall be covered by the various drilling rates.

No measurement for payment shall be made for the redrilling of any drilled hole due to wedging

caused by the excessive wear of drill bits. No measurement for payment shall be made for

providing another hole or for cleaning a drilled hole that becomes clogged or obstructed before

the completion of flushing, pressure washing, water testing, grouting, or borehole surveys.

Redrilling required of grout holes due to the Contractor's failure to clean out a hole before grout

in the hole has set, shall not be measured for payment, except in the case where the Engineer

has instructed the Contractor that the grout be allowed to set.

No measurement for payment shall be made for interrupting the drilling to flush or pressure

wash the boreholes and to perform water pressure tests, to survey the boreholes, or to flush,

rinse and grout sections of boreholes that are being drilled. In the case of grout holes the



150

Contractor would be entitled to additional measurement under Clause 11A.8.2.1 if the drilling

equipment has been moved, with the approval of the Engineer, to drill another grout hole while

grouting of the particular hole is in progress.

8.1.1 Rotary Core Drilling

The quantity to be paid for shall be the linear metre actually drilled to the satisfaction of the

Engineer. All measurements of depths drilled shall be measured from the point at which physical

drilling commences.

Consistency and Hardness

For measurement and payment purposes distinction shall be made between the consistency

and hardness of the materials drilled as follows:

Category A : All materials that can be augered.

Category B : Material (rock) that cannot be augered.

Gravel

Gravel shall be defined to be any hard aggregate of average dimension between 10mm and

50mm, with or without a matrix of loose material, and which moves during drilling, resulting in

difficult drilling, and where the hard aggregate occupies more than 30% of the volume of the

hole (measured per individual drill run).

Boulders

The definition shall be as for gravel but the average dimension shall be between 50mm and

300mm.

Inclined drilling

Payment for inclined holes shall be an extra over payment per metre of hole drilled.

Concrete drilling

Any drilling through concrete shall be measured under category B material. Where steel is

encountered in reinforced concrete, this shall be measured and paid for per millimetre

(measured as the diameter of the bar cut). Where a bar is cut more than once, each cut shall be

measured separately.

8.2 Scheduled Items

8.2.1 Setting up over Holes Unit: No

The rates shall cover all costs of setting out the hole position, setting up plant and equipment at

each hole and moving the same to the next hole, including for handling and transporting plant

and equipment, any excavation, or filling necessary for setting up platforms, and cleaning up on

completion of each hole.

Adjustment of the drilling equipment to deal with a number of angled holes at one position shall

not be regarded as separate setups.

Separate items shall be provided for different types of drilling equipment.

For holes to be drilled in stages conforming to the specified grouting stages, setup measurement

shall be made for each setup.

8.2.2 Drilling Unit: metre (m)

Measurement shall be the length of hole drilled as detailed on the Drawings or as instructed by

the Engineer. Distinction shall be made between percussion drilled holes, rotary core drilled

holes and the size of holes drilled.



151

Separate items will be provided for: i) 0 – 25m depth

ii) 25 – 50m depth

iii) over 50m depth

The tendered rate shall cover the cost for drilling holes inclined at 0° to 30° to the vertrical, but

extra over payment items will be provided for drilling at inclinations to the vertical as follows:

i) 31° – 60°

ii) 61° – 90°

The rate tendered for percussion drilled holes shall cover all variations in strata encountered

(including mass or dental concrete) and the direction and inclination of the hole and include full

compensation for all labour, materials, including drilling fluid and work required to drill the holes

to the required depth.

The rate tendered for rotary core drilled holes shall cover all strata encountered and separate

items shall be specified for Category A and B materials, gravel and boulders. Drilling through

concrete shall be measured as Category B material. The rate tendered shall include the supply

and usage of all labour, materials (including drilling fluid), tools, equipment and plant to drill the

holes to the required depth.

Extra over payment items shall be specified for drilling in confined spaces such as galleries.

8.3 Scheduled Items Unit: metre (m)

Measurement shall be the length of hole redrilled where grout has been allowed to set on

instruction of the Engineer. Grouted holes redrilled on account of the Contractor’s failure to flush

out grout before it has set, shall not be measured. The redrilling shall be percussion drilled.

The tendered rate shall cover the cost for drilling holes inclined at 0° to 30° from the vertical.

Separate extra over items will be provided for drilling at inclinations to the vertical as follows:

i) 31° – 60°

ii) 61° – 90°

The rate shall include full compensation for all work required to redrill grouted holes, irrespective

of the depth of grouted hole.

8.4 Casing Unit: metre (m)

Measurement for payment for casings shall be for any type of drilled holes. No distinction shall

be made between installing casings in vertical or inclined holes. Distinction shall be made for the

drilling method used, size of hole, temporary and permanent casing.

The rates shall cover all costs for the supply and placing of all materials, labour, tools,

equipment and plant necessary to complete the work as specified in this Specification,

regardless of the depth to which casing is installed. No extra measurement for payment shall be

made for the use of drilling fluids or muds for the installation of casing.

8.5 Core recovery Unit: metre (m)

Measurement of core recovery in all types of material will be the length of core recovered from

the core barrel and placed in core boxes. The rates tendered for core recovery shall include full

compensation for special methods adopted during core drilling and core extraction to ensure

recovery of the greatest possible length of complete core and for placing in core boxes.

8.6 Core boxes Unit: No



152

Measurement will be by the number of core boxes required. The rate tendered shall include full

compensation for the supply to Site of core boxes, the temporary waterproof storage (if required)

on Site of boxes and cores and transport to permanent storage on site.

8.7 Standpipes for grout holes Unit: No

The number of holes, into which a standpipe is installed, shall be measured. The rate shall cover

all costs incurred in complying with the relevant requirements of Clause 11A.5.3.

8.8 Grouting of holes for stabilization Unit: kg

The weight of cementitious material approved or instructed by the Engineer as being necessary

for grouting of the sections of any hole for the stabilisation of unstable sidewalls shall be

measured. The rate shall include all costs for the supply of all materials, labour, tools, plant and

equipment, preparation and insertion of the grout. Redrilling through set grout shall be measured

in terms of the appropriate clause in this Specification.

8.9 Plugging of holes Unit: metre (m)

The total length of the holes which were plugged as instructed by the Engineer shall be

measured for the different hole sizes. The rate shall cover all costs for the supply of the

materials, labour, plant and equipment as well as the removal of all concrete caps and uPVC

pipes which were inserted in the exploratory holes. No distinction shall be made between

backfilling through a tremie pipe or from the top. Where it is required to redrill exploration holes,

setups and drilling shall be measured in terms of the appropriate clauses in this Specification.

8.10 Marking of exploratory holes Unit: No

The rate shall include all labour, materials, including cement, sand, 16mm steel rod, excavation,

mixing, placing, marking to supply and install the concrete block marker in accordance with

Clause 11A.5.10 of this Specification.

8.11 Standard Penetration Test (SPT) Unit: No

The rate shall cover all the costs to carry out and complete each SPT as ordered by the

Engineer according to Clause 11A.7.1 of this Specification.

8.12 Standby Unit: h

The unit of measurement shall be the time in hours that the different drill rigs or grouting

equipment are on standby as ordered by the Engineer to await the Engineer’s instruction to

complete the drilling/grouting or to be moved. The rate shall cover the cost of keeping the drill

rig, drilling personnel and other equipment and materials on standby. It shall not cover any time

during which plant and labour are standing by while tests or any other operations by the

Contractor that are necessary for the completion of the drilling are being carried out.



153

Figure 11.1 – Details of Core Box



154

Figure 11.2 – Labelling of Core Box



155

PARTICULAR SPECIFICATION B3: WATER PRESSURE TESTING OF BOREHOLES

1. SCOPE ......................................................................................................................................... 156 2. DEFINITIONS ............................................................................................................................... 156 3. MATERIALS ................................................................................................................................. 156 3.1 Water ............................................................................................................................................ 156 4. EQUIPMENT ................................................................................................................................ 156 4.1 Water Pumps ............................................................................................................................... 156 4.2 Packers ........................................................................................................................................ 157 4.3 Gauges and Meters .................................................................................................................... 157 5 EXECUTION ................................................................................................................................. 157 5.1 General Procedures for Water Pressure Testing .................................................................... 157 5.2 Comprehensive Water Pressure Tests ...................................................................................... 158 5.3 Abbreviated Water Pressure Tests ............................................................................................ 160 5.4 Water Test Records .................................................................................................................... 160 6 TOLERANCES ............................................................................................................................. 160 7 TESTING ...................................................................................................................................... 160 8 MEASUREMENT AND PAYMENT .............................................................................................. 160 8.1 General Principles ....................................................................................................................... 160 8.2 Scheduled Items .......................................................................................................................... 161 8.2.1 Connections to drilled holes ...................................................................................................... 161 8.2.1.1 Connections for performing comprehensive water pressure tests using a single packer ............... 161 8.2.1.2 Connections for performing comprehensive water pressure tests using double packers ............... 161 8.2.1.3 Connections for performing abbreviated water pressure tests using a single packer .................... 161 8.2.1.4 Connections for performing abbreviated water pressure tests using double packers .................... 161 8.2.2 Comprehensive water pressure tests of 50 minutes duration ........................................................ 161 8.2.3 Comprehensive water pressure tests of 15 minutes duration ........................................................ 161 8.2.4 Extra over Clauses 11B.8.2.2 or 11B.8.2.3 as applicable for measuring the rate of fall of

water levels in boreholes ............................................................................................................... 161 8.2.5 Abbreviated water pressure tests .................................................................................................. 161 8.2.6 Extra over Clause 11B.8.2.5 for pressure washing of holes .......................................................... 161



156

1. SCOPE

This specification deals with performing:

a) comprehensive water pressure tests generally conducted in exploratory holes but also in

any other drill holes such as grout holes, and

b) abbreviated water pressure tests usually conducted in grout holes as part of the routine

testing procedures associated with grouting operations.

The disposal of waste water, keeping accurate daily records of all test results, the submission of

the test results to the Engineer on approved forms, the cleaning up of the areas upon

completion of the work and all other work incidental to the performance of the above operations

fall within the scope of this specification.

2. DEFINITIONS

The following definitions shall apply :

“Lugeon unit” : A water take of 1 litre per minute per metre length of hole tested at a pressure of 1MPa. For tests carried out at other pressures:

UL = water taken in pressure test (litre/metre/min) x 1000 P Where

UL = unit water loss in Lugeon units P = gauge pressure at borehole collar in kPa + (10 x ℓ x sin Ø) - pressure loss in drill rods Ø = angle of hole from horizontal ℓ = half length of stage + length of previous stage(s)

“Stage” : The portion of a hole that is to be drilled, water pressure tested and (where applicable)

grouted.

“Flushing” : The cleaning of a borehole by inserting a suitable pipe or tube down to the bottom of

the hole or stage and pumping in a mixture of air and water while moving the pipe up and down

until the wash water runs clear.

“Pressure washing” : The cleaning of seams and crevices containing clay or other materials by

pumping water into a borehole or section of a borehole sealed off by means of a packer(s) while

the water take is recorded at 5-minute intervals. Wash water is allowed to escape from surface

openings or adjacent, interconnecting boreholes and gives an indication whether fracture filling

is being removed.

3. MATERIALS 3.1 Water

Water used for water pressure testing shall be clean and free from injurious amounts of acids,

alkalis, suspended clay and other substances which may have a detrimental influence on the

water pressure test or on subsequent grouting operations.

4. EQUIPMENT 4.1 Water Pumps



157

The test pump shall be of the centrifugal type or of the positive displacement type capable of

delivering at least 100 litres of water per minute at a pressure of 1MPa measured at the

borehole collar. Where a positive displacement type pump is used an air vessel shall be fitted to

the pump with a size capable of limiting the range of pressure to 5% of the mean pressure.

4.2 Packers

Single and double packers or obturators at least 500mm long capable of sealing percussion or

rotary core drilled holes of any size between 100mm and 38mm, both sizes inclusive, at a

maximum pressure of 1MPa shall be available so that any section of a hole can be tested at any

stage of the drilling. The packers shall be of the pneumatic or hydraulic type or of soft

expandable rubber capable of sealing tightly against the sides of the hole, particularly when the

material is soft or friable to the extent that enlargement of the hole is unavoidable. The packers

shall be so designed that they can withstand the specified water pressure, to a maximum of

1MPa, without leakage. Mechanically expanded packers may be used at the top of the hole for

single stage testing if approved by the Engineer, but pneumatic or hydraulic packers shall be

used where the hole has to be sealed at depth.

4.3 Gauges and Meters

The water pressure gauges shall be precision instruments of durable construction, graduated to

read in increments of 10kPa and accurate to within 5%. Pressure gauges shall be oil actuated

and shall have a range of approximately twice the expected maximum pressure for the particular

borehole. The pressure gauges shall not be throttled to damp pressure surges and shall be

connected to indicate the water pressure at the borehole collar.

The water meter shall be of the integrator type accurate to within 2% for flows from 1,0 litres per

minute to 100 litres per minute. All water meters and pressure gauges shall be sealed and

calibrated by an approved hydraulics laboratory before use on the Site. If at any time during the

execution of the work the Engineer reasonably suspects that the equipment is defective, the

Contractor shall, if so ordered, have the same tested and recalibrated at an approved laboratory.

When water losses are small, or if the Engineer desires to check the water meter, the flow

recordings are to be supplemented by flow measurements taken from a specially calibrated

suction tank. The suction tank shall be kept on Site at all times.

Calibration of the water testing equipment shall be done whenever ordered by the Engineer by

determining the pressure loss at flows of 20%, 40%, 60%, 80% and 100% of the pump output

for various total rod lengths in increments of 10m up to the maximum depth of hole envisaged.

These calibration tests shall be done with the rods laid horizontally with pressure gauges

installed at both ends. A device for regulating the outflow of the water shall be provided at the

outlet end. The calibration shall be done in the presence of the Engineer, who shall prepare

diagrams of pressure loss versus flow for different rod lengths.

5 EXECUTION 5.1 General Procedures for Water Pressure Testing

(a) Supervision and Responsibility

The Contractor shall continuously supervise water pressure testing operations and measure and

regulate the pressures so that they are at all times in accordance with the Engineer's

requirements. The Contractor shall ensure that there is no damage as a result of performing

water pressure tests. Pressure washing operations shall only be performed in the presence of

the Engineer or his duly authorised representative.

(b) Cleaning Holes before Testing

Any stage or section of any hole to be water tested shall be cleaned immediately prior to water

pressure testing by flushing.

(c) Surface Leaks



158

Where surface leaks are excessive the Contractor shall plug such surface leaks as directed by

and subject to the approval of the Engineer, and shall ensure at all times that no rock

movements occur. The points of emergence of any water on the surface shall be noted, their

positions recorded and an estimate of the flow rate made.

5.2 Comprehensive Water Pressure Tests

Comprehensive water pressure tests shall generally only be performed if required by the

Engineer on sections of grout holes. The tests shall be conducted in rock or boulder formations,

provided that a tight packer seal can be achieved. Unless otherwise ordered, downstage testing,

using a single packer, shall be performed in sections of holes between 3m and 6m long and be

conducted after the completion of the drilling of each consecutive test length, and in any event

before correcting any caving. The test section shall be flushed to remove all drill cuttings before

commencing the test. In caving ground the upper portions of the hole shall all have been water

tested to the satisfaction of the Engineer prior to correcting the caving.

Specific sections of a hole shall be tested by using double packers if required by the Engineer.

The test length of such sections can vary depending on the circumstances but would generally

be between 0,5m and 12m long.

Comprehensive water pressure tests shall generally be conducted by performing five

consecutive tests, each of ten minutes duration per single test section so that :

- 1st 10-minute interval is at a low pressure .............................................................. (pressure A)

- 2nd 10-minute interval is at a medium pressure ..................................................... (pressure B)

- 3rd 10-minute interval is at a peak pressure ............................................................ (pressure C)

- 4th 10-minute interval is at a medium pressure ....................................................... (pressure B)

- 5th 10-minute interval is at a low pressure ............................................................... (pressure A)

The pressures to be applied are governed by the depth of the stage under test and by the

competency of the rock to withstand the pressure. Unless otherwise ordered by the Engineer,

the pressures A, B and C shall be as shown in the following schedule:



159

SCHEDULE OF TEST PRESSURES

DEPTH* OF (UPPER) PACKER

BELOW SURFACE (m)

SURFACE PRESSURE (kPa)

A B C

1,0

2,0

3,0

4,0

5,0

6,0

9,0

12,0

15,0

18,0

21,0

24,0

27,0

30,0

33,0

36,0

39,0

42,0

45,0

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

-

2.0

3,0

4,0

5,0

6,0

9,0

12,0

15,0

18,0

21,0

24,0

27,0

30,0

33,0

36,0

39,0

42,0

45,0

60,0

10

20

30

35

45

55

80

110

135

165

195

220

255

280

310

340

350

350

350

15

30

50

65

80

95

140

190

240

285

340

390

440

490

545

595

640

690

700

25

45

70

90

115

135

200

270

340

405

485

555

630

700

780

850

915

985

1 050 (max)

*Depth (D) of packer in inclined holes to be determined by : D = d x sin ø where d = length of borehole at packer position ø = angle of hole from horizontal. The water level within the borehole shall be measured before commencing the test. The Engineer may from time to time require that the borehole above the packer be filled with water during testing to observe if a possible rise of the water level occurs, indicating that the packer has not sealed effectively. If the loss of water due to rock fracturing is such that the required pressure cannot be obtained, the test shall be conducted at the highest pressure that the equipment is capable of producing in that particular test section. The test shall then be performed for 15 minutes while the pressure and water take are recorded at 5-minute intervals. If ordered by the Engineer, the Contractor shall fill the hole with water and observe the rate of fall of water levels as directed by the Engineer. The pressures applied and the sections to be tested are all subject to variation by the Engineer in order to obtain the maximum information from each test. Should any difficulty be experienced with the water pressure testing or any particular section of a hole the Engineer shall be informed immediately in order to decide what action must be taken. In general if a test section cannot be properly sealed the packer(s) shall be moved to the position(s) used for the previous successful test and the two sections tested together at pressures equal to those used in the previous test. The Contractor shall in such instances obtain from the Engineer instructions as to what further testing (if any) must be performed. The accuracy of the individual water pressure tests and of the sealing of the packers shall be checked at regular depth intervals to be decided by the Engineer, but shall generally be conducted by performing check water pressure tests on sections of hole approximately 12m long. The Engineer shall be informed immediately of the results of the check water pressure tests if these differ by more than 10% from the results of the sum of the individual water



160

pressure tests. Where the length of hole not yet subjected to a check water pressure test exceeds 3,0m and it becomes necessary to correct caving, a check water pressure test shall be performed before correcting any caving.

5.3 Abbreviated Water Pressure Tests

Unless the Engineer requires that a comprehensive water pressure test be conducted in accordance with this specification, an abbreviated water pressure test, as described hereinafter, shall be conducted on each stage or section of every curtain grout hole immediately prior to grouting that stage or section. If so ordered by the Engineer to establish the effectiveness of the grouting operation, abbreviated water pressure tests of grouted holes shall be performed, but not before at least 6 hours has elapsed after grouting has been completed.

The test section shall be flushed to remove all drill cuttings before commencing the test. Water shall then be pumped into the hole or stage or section of hole ordered by the Engineer until the pressure rises to 100kPa at the collar of the hole. A lower pressure shall be applied if directed by the Engineer in areas of possible rock movement. The pressure shall be maintained constant for 15 minutes and the rate of flow shall be measured and recorded at 5-minute intervals. If the leakage is too great to enable the specified pressure to be attained then the discharge of the pump shall be maintained at a constant rate for 10 minutes at the maximum output of the test pump and be recorded, while the pressure in the hole is measured and recorded at 2-minute intervals.

The unit water loss in Lugeon units shall be calculated and recorded by the Contractor for each time interval of the test.

In the case where increasing water takes for a specific test section are measured, and where connection to adjacent holes has been established, the Contractor shall inform the Engineer or his authorised representative before removing the packer(s). Under such circumstances and if directed by the Engineer the Contractor shall pressure wash the relevant test section. Such pressure washing shall be performed in the presence of the Engineer or his authorised representative, using such pressures and for such durations as may be directed.

5.4 Water Test Records

The Contractor shall each day provide the Engineer with an accurate record of all comprehensive and abbreviated water tests on forms approved by the Engineer. The forms shall inter alia make provision for recording the borehole number, section tested, date and time of test, the duration of the test, test pressures, measured water loss, unit water loss (UL) in Lugeon units, the water level prior to testing and any general remarks. Aspects such as surface leaks, ineffective packer sealing and any sudden changes in pressures and water takes shall also be recorded.

6 TOLERANCES

Not applicable. 7 TESTING

Not applicable. 8 MEASUREMENT AND PAYMENT 8.1 General Principles

Water pressure testing in boreholes shall be measured by the number of tests satisfactorily performed and for which complete records have been produced. The rates for pressure testing shall include for the cleaning up of the areas upon completion of the work, for measuring water levels prior to testing, for flushing the test section prior to testing and shall include for all costs in connection with the keeping of records. The payment for testing and recalibration of equipment shall be determined in accordance with the provisions of the General and Special Conditions of the Contract.



161

No additional payment for the water used for the execution of water pressure tests shall be made. The Contractor shall be entirely responsible for damage as a result of errors that he may make in performing water pressure tests and shall at his own cost repair such damage.

8.2 Scheduled Items

8.2.1 Connections to drilled holes

The rates for payment shall cover all costs for connections to drilled holes for water pressure testing purposes. Separate items shall be provided for the different types of tests, but no distinction shall be made between different hole diameters.

8.2.1.1 Connections for performing comprehensive water pressure tests using a

single packer Unit: No

The number of connections shall be measured. A connection shall be measured once only for each test section of a borehole regardless of the number of times the packer is adjusted or reseated.

8.2.1.2 Connections for performing comprehensive water pressure tests using

double packers Unit: No

The number of connections shall be measured. A connection shall be measured once only for each test section of a borehole regardless of the number of times the packers are adjusted or reseated.

8.2.1.3 Connections for performing abbreviated water pressure tests using a

single packer Unit: No

The number of connections shall be measured. A connection shall be measured once only for each test section of a borehole regardless of the number of times the packer is adjusted or reseated.

8.2.1.4 Connections for performing abbreviated water pressure tests using double

packers Unit: No

The number of connections shall be measured. A connection shall be measured once only for each test section of a borehole regardless of the number of times the packers are adjusted or reseated.

8.2.2 Comprehensive water pressure tests of 50 minutes duration Unit: No

The number of separate comprehensive water pressure tests of 50 minutes duration which are satisfactorily performed, shall be measured.

8.2.3 Comprehensive water pressure tests of 15 minutes duration Unit: No

The number of separate comprehensive water pressure tests of 15 minutes duration which are satisfactorily performed, shall be measured.

8.2.4 Extra over Clauses 11B.8.2.2 or 11B.8.2.3 as applicable for measuring

the rate of fall of water levels in boreholes

Unit: h

The duration for which the Engineer has ordered the observation and measurement of the rate of fall of the water levels to continue per borehole, shall be measured regardless of the number of measurements.

8.2.5 Abbreviated water pressure tests Unit: No

The number of separate water pressure tests, which are satisfactorily performed, shall be measured. No distinction shall be made between tests of 15 minutes and of 10 minutes duration.

8.2.6 Extra over Clause 11B.8.2.5 for pressure washing of holes Unit: h



162

The duration ordered by the Engineer for washing holes under pressure shall be measured regardless the pressures used.



163

PARTICULAR SPECIFICATION B4: GROUTING

1. SCOPE ......................................................................................................................................... 164 2. DEFINITIONS ............................................................................................................................... 164 3. GROUT ......................................................................................................................................... 165 3.1 General ........................................................................................................................................ 165 3.2 Materials ...................................................................................................................................... 165 3.2.1. Cementitious Materials .............................................................................................................. 165 3.2.2. Water ............................................................................................................................................ 166 3.2.3. Sand ............................................................................................................................................. 166 3.2.4. Chemical Grouts ......................................................................................................................... 166 3.2.5. Bentonite ..................................................................................................................................... 166 3.2.6. Additives and Admixtures ......................................................................................................... 166 3.2.7. Grout Mix ..................................................................................................................................... 166 4. PLANT AND EQUIPMENT .......................................................................................................... 167 4.1. General ........................................................................................................................................ 167 4.2. Grout Pumps ............................................................................................................................... 167 4.3. Mixers .......................................................................................................................................... 167 4.4. Water Storage Tank .................................................................................................................... 167 4.5. Gauges and Meters .................................................................................................................... 168 4.6. Packers ........................................................................................................................................ 168 4.7. Supply and Return Lines and Grouting Pipes, Hoses and Fittings ...................................... 168 4.8. Bentonite Mixers ......................................................................................................................... 168 4.9. Measuring Equipment for Trial Mixes ...................................................................................... 169 5. CONSTRUCTION ......................................................................................................................... 169 5.1. General ........................................................................................................................................ 169 5.2. Drilling Grout Holes .................................................................................................................... 170 5.3. Standard Grouting Methods ...................................................................................................... 170 5.3.1. General Procedure for Grouting ............................................................................................... 170 5.3.2. Specific Procedure for Curtain Grouting ................................................................................. 173 5.3.3. Specific Procedure for Consolidation Grouting ...................................................................... 175 5.4. Specialised Grouting Methods .................................................................................................. 175 5.4.1. General ........................................................................................................................................ 175 5.4.2. Tube-a-manchette (TAM) Grouting Method ............................................................................. 176 6. TOLERANCES ............................................................................................................................. 176 7. TESTING ...................................................................................................................................... 176 7.1. Density (Mud Balance) ............................................................................................................... 176 7.2. Viscosity (Marsh Cone) .............................................................................................................. 177 7.3. Bleeding ....................................................................................................................................... 177 7.4. Test Cubes .................................................................................................................................. 177 8. MEASUREMENT AND PAYMENT .............................................................................................. 178 8.1. General Principles ...................................................................................................................... 178 8.2. Scheduled Items ......................................................................................................................... 178 8.2.1. Grout Connections to Drilled Holes ......................................................................................... 178 8.2.2. Grouting ....................................................................................................................................... 178 8.2.3. Materials used in all Grouting Operations ............................................................................... 178 8.2.3.1. Cementitious material ................................................................................................................ 178 8.2.3.2. Sand ............................................................................................................................................. 179 8.2.3.3. Additives ...................................................................................................................................... 179 8.2.3.4. Chemical grouts ......................................................................................................................... 179 8.2.4. Grout Cap .................................................................................................................................... 179 8.2.5. Rinsing drilled holes .................................................................................................................. 179 8.2.6. Tube-a-manchette (TAM) grouting ............................................................................................ 179 8.2.7. Density (Mud Balance) Test ....................................................................................................... 179 8.2.8. Viscosity (Marsh Cone) Test ..................................................................................................... 179 8.2.9. Bleed Test .................................................................................................................................... 179 8.2.10. Test Cubes .................................................................................................................................. 179



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1. SCOPE

This specification deals with the construction of a grout curtain along lengths of the dam

foundation, performing consolidation grouting of the rock below highly stressed parts of the

foundation and the final plugging of grout holes, in accordance with the Drawings or instructions

of the Engineer.

The work shall consist of flushing grout holes, making grout connections, supplying, mixing and

injecting grout into holes, disposing of waste water and grout, cleaning up of the areas upon

completion of the work and all such other operations as are incidental to grouting.

2. DEFINITIONS

The following shall apply :

“Cavity grouting” : Grouting to fill any voids in rock/concrete or first stage/second stage

concrete interfaces around structures.

“Cement” : All cementitious materials including pozzolans and pseudo pozzolans.

“Consolidation grouting” : Grouting to improve the quality of the rock mass, over an area, by

injecting grout through rows of holes of generally shallow depth. Where the grouting is

performed through concrete, consolidation grouting includes grouting of the contact between the

concrete and the rock mass.

“Contact grouting” : Grouting of embedded steel to fill any voids at steel/concrete interfaces.

“Curtain grouting” : Grouting a row or rows of holes in the rock mass to create a continuous

impervious curtain of grout.

“Depth” : The distance from the mouth of the hole regardless of direction.

“Downstage grouting” : The process of drilling a hole to a limited depth (stage), grouting to

that depth, either washing out the grout hole after the injected grout has attained its initial set or

redrilling through grout in holes that are not flushed after grouting, drilling the hole to a further

depth after the specified length of adjacent grout curtain for the particular stage has been

completed and also after at least 24 hours has elapsed since grouting the previous stage and

then grouting the further depth (next stage). Thus the hole is successively drilled and grouted

until the required depth is completely grouted to the satisfaction of the Engineer.

Downstage grouting can further be subdivided into:

(a) Grouting of each stage with the packer set at the surface. This shall include for a hole

which is completely grouted from bottom to surface in one operation.

(b) Grouting each stage with the packer set at the bottom of the previous stage.

“Grout cap” : A concrete cap constructed along the line of the curtain grout holes and

embedded into the rock, usually in areas where the surface rock is weak or is highly fractured.

“Grout take” : Grout take is the consumption of cement by mass (kilogram) per metre length of

a hole.

“Rinsing” : The circulation of clean water in boreholes to prevent the clogging of such open

boreholes due to the ingress of grout.

“Stable cement grout” : A homogeneous balanced blend of water and cement combined with

selected additives and admixtures to produce a product with minimal bleed, low cohesion and

good resistance to pressure filtration.



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“Stage” : A portion of a hole that has been drilled and is to be grouted. The depths of the

grouting stages shall be as indicated on the Drawings, or directed by the Engineer.

“Upstage grouting” : The process of drilling a hole to full depth initially and grouting from the

bottom of the hole upward at different depths by means of a packer set at different depths.

Upstage grouting shall be performed by attaching a packer to the end of the grout supply pipe,

lowering the grout supply pipe into the hole to the top of the lowest section to be grouted,

expanding the packer, grouting at the required pressure, allowing the packer to remain in place

until there is no back pressure, withdrawing the grout supply pipe to the top of the next higher

section to be grouted and thus successively grouting the hole in sections at the specified

pressures until the entire hole is completely grouted.

3. GROUT 3.1 General

Grout shall generally consist of a suitable mixture of a homogeneous balanced blend of cement,

additives, admixtures and water that comply with this specification. No lumps shall be permitted

in the grout mixture. All grout mixtures specified in this specification shall be by volume and shall

be batched by volume unless batching by weight is approved by the Engineer.

Where grout is required to fill large cavities the Contractor shall obtain the Engineer's

instructions regarding the possible use of a filler, such as sand that complies with this

specification. The use of admixtures to control the rate of setting of the grout shall be subject to

the approval or direction of the Engineer. The proportions of cementitious material, water and

sand and any admixtures used shall be as approved or directed by the Engineer and shall be

varied to meet the characteristics of each hole as determined by conditions encountered from

time to time.

Grout that has not been injected within two hours after mixing shall not be used for grouting, and

shall be disposed of as directed.

The method of batching shall be such that the ingredients are proportioned to an accuracy of

within 5%. Where sand is added to the grout, frequent bulking and moisture content

determinations shall be made and the necessary adjustments made to the batching proportions.

Prior to introducing the mixed grout into the grout circuit, it shall be mixed for at least 5 minutes,

as measured from the instant when all the ingredients have been added.

3.2 Materials

3.2.1. Cementitious Materials

Cement shall be either CEM 1 Class 42.5 N Ordinary Portland Cement (OPC) or CEM 1 Class

42,5N Rapid-hardening Cement (RHC) or CEM 1 Class 52,5N (RHC), all complying with the

requirements of SANS 50197-1 and passing a 0,090mm sieve, while not more than 10% shall

be retained on a 0,045mm sieve. The Blaine fineness shall be greater than 440m²/kg. RHC shall

only be used where the Engineer is of the opinion that improved grout injection can be achieved

due to the greater fineness of the cement. In the event that cement is found to contain lumps of

foreign matter of a nature and in amounts which in the opinion of the Engineer may be

deleterious to the grouting operation, screening through a standard No 100 square mesh screen

may be required.

All cementitious materials shall be obtained from approved sources. Bagged cementitious

material shall not be stored for longer than 30 days and shall be delivered in 50kg multi-walled

paper sacks. The volumes of standard 50kg sacks of cementitious materials shall be determined

by the Contractor in the presence of the Engineer for each type of cementitious material.

Separate storage facilities shall be provided on Site for each type of cementitious material used. During transportation, storage and at the place of the grouting activity, all bagged cementitious



166

materials shall be kept covered to provide proper protection against moisture and other factors that may promote deterioration of the materials. Sheds for the storage of bagged cementitious materials shall be dry, well ventilated, weatherproof and watertight. The bags shall not be stored or placed in contact with the floor or ground. The Contractor shall provide sufficient storage capacity to cater for at least one week's peak production of grouting.

3.2.2. Water

The water used in the grout and in the work described in this specification shall be fresh, clean and free from suspended matter and injurious amounts of oil, acid, alkali, salts, organic matter

and other substances that may impair the strength and durability of the grout. The Contractor shall provide an adequate water supply, from an approved source, in order that all operations necessary for performing the work described in this specification, such as drilling, pressure washing, rinsing, water pressure testing, flushing and grouting can be performed at the maximum efficiency.

3.2.3. Sand

Sand shall be from a source approved by the Engineer and shall comply with the relevant requirements of SANS 1083 for sand for concrete, shall be washed as necessary and thereafter screened to pass a 300 micron sieve.

3.2.4. Chemical Grouts

In special circumstances the use of proprietary grouts of a non-cementitious nature may be approved or ordered by the Engineer. Such grouts shall be handled, stored, mixed and injected in strict conformity with the manufacturer's instructions.

3.2.5. Bentonite

Bentonite shall be of approved manufacture and shall consist of pulverised natural sodium montmorillonite clay supplied in free-flowing granular form and shall comply with the relevant requirements of API SPEC 13A. The Contractor shall submit the results of tests performed, by a laboratory approved by the Engineer, in accordance with API SPEC 13A on each consignment of bentonite delivered to Site to confirm its compliance with the specified requirements. Peptised or other specially treated bentonite shall not be used.

Bentonite shall be delivered to Site in sacks not exceeding 50kg by mass and shall be stored in a shed that complies with the requirements specified in Clause 11C.3.2 of this specification for cementitious materials.

3.2.6. Additives and Admixtures

Admixtures such as plasticisers, accelerators, retarders, thixatropic agents and anti-washout agents may be used only with the approval of the Engineer. In support of the request to use additives and admixtures, the Contractor shall submit the results of relevant laboratory tests that have been performed on site with the grout materials that will be used to demonstrate the effectiveness and advantages of the product(s). Unless the chemical composition of such products is made known, such products will not be acceptable for use in the grout. Additives and admixtures used shall comply with AST C-494, AASH M-54 or BS 5075.

3.2.7. Grout Mix

The grout mix is specified as the ratio of water : cementitious material by volume. The grout mix design shall ensure that only stable grouts will be used. The permeability of the foundation rock as determined by water pressure tests may require that grouting may be started with a thinner grout mix, which can be thickened as grouting proceeds. Acceptable grout mixes will normally

be allowed to vary between water : cement ratios of 2 : 1 and 0,6 : 1. Other grout mix parameters shall be as follows:

Bleed : <5% at 2 hours

Apparent viscosity : Maximum 60 seconds (Marsh Cone)

Strength : Minimum 25MPa cube strength at 28 days



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The contractor shall perform sufficient laboratory tests on the grout mix proportions for acceptance by the Engineer before any grout operations will be allowed to commence.

4. PLANT AND EQUIPMENT 4.1. General

All grouting equipment shall be of the most modern type with adequate capacity, in good mechanical order and suitable for doing the work. All equipment shall be satisfactorily maintained to ensure continuous and efficient performance during all grouting operations. Any grout hole that is lost or damaged due to mechanical failure of equipment or inadequacy of grout supply shall be replaced by another hole drilled by the Contractor. The equipment available shall be capable of grouting all sizes of hole between 100mm and 38mm, both sizes inclusive. Adequate measures shall be provided to protect the equipment and materials from damage of

whatever nature. The grout lines shall be the shortest practical to prevent wastage of materials, high pressure drops or clogging of the lines. Adequate compressor capacity for the optimal performance of air driven equipment shall be provided. Prior to commencing any grouting, the Contractor shall submit to the Engineer for his approval full details of his proposed plant and equipment and also of the proposed layout of the plant. The Contractor shall at all times during grouting operations have 100% standby equipment of all types available to ensure that grouting operations can be continued without significant interruptions caused by breakdowns of equipment.

4.2. Grout Pumps

Grout pumps shall be of the positive displacement, centrifugal or the helical rotor type. Stand-by

pumps shall be available on Site during grouting operations. Pumps shall be equipped with

quick acting lubricated plug valves, an accurate pressure gauge and a bypass from the pump

discharge to the tank or inlet to the mixer. A screen having square openings of 3mm size shall

be provided at the intake of the pump, and all pumps shall have interconnecting pipes and

valves to permit the immediate transfer, if necessary, to stand-by equipment so that there will be

no interruption in the flow of grout to a hole that is being injected.

Grout pumps shall be capable of injecting grout at a rate of between 50 litres per minute and

100 litres per minute at a pressure of double the grout injection pressure shown on the

Drawings. The rate of pumping shall be readily and accurately adjustable from zero flow to the

maximum capacity, and equipment shall be such that grout consistency can be adjusted without

causing an interruption in the flow, which could result in setting of the grout before pumping is

resumed. Pumps shall be fitted with preset relief valves.

4.3. Mixers

Grout mixers shall be either air or electrically powered, and shall be single or double

compartment high speed (minimum 1200rpm) colloidal mixers that are capable of supplying a

continuous flow of well mixed grouting ingredients. The mixers shall be provided with a device

for accurately measuring the volume of mix water in litres. Where a single compartment mixer is

used, a sump tank equipped with mechanical agitators to keep the cementitious materials in

suspension shall be provided to ensure an uninterrupted supply of well mixed grout to the point

of injection. Mixers shall be of sufficient capacity to ensure that the grout pumps can be supplied

at their maximum pumping capacity.

4.4. Water Storage Tank

A tank of sufficient capacity and adequate bypass pipes and fittings for auxiliary water supply

shall be available to be used for water pressure testing, flushing and pressure washing

operations.



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4.5. Gauges and Meters

Pressure gauges shall be installed at the collars of all holes being grouted and at the grout

pump outlet. The pressure gauges shall all be numbered for identification, shall be oil actuated

and shall have a maximum scale deflection not exceeding approximately twice the expected

maximum pressure for the particular stage being grouted. A master pressure gauge, graduated

in divisions of 10kPa and calibrated by a recognised testing authority, shall be kept on Site for

checking and calibrating the working pressure gauges. The master gauge shall not be used for

any other purpose and the metering accuracy shall be 3%.

The working pressure gauges shall be calibrated to read in kPa, and be graduated in divisions

of 10kPa and have an accuracy of 5%.

A flow meter shall be used to accurately measure grout mix water.

Pressure gauges and flow meters shall be calibrated regularly and a 100% replacement stock of

working gauges and meters shall also be on hand at all times. Working gauges shall not be

used for longer than 50 hours of operation after which they shall be cleaned and re-calibrated.

Where ordered by the Engineer, displacement gauges shall be provided to enable any rock

movement during grouting to be measured. A displacement gauge may consist of a screw

adjusted spirit level on a steel straight edge 2m long, or other approved device.

4.6. Packers

Surface packers shall, in general, be used, but packers suitable for isolating a section of a hole

at depth shall also be available on Site.

Generally, packers shall consist of pneumatic or hydraulic tubes, mechanically expanded tubes

or mechanically expanded rings of rubber, leather or other suitable material attached to the end

of the grout injection pipe. The packers shall be so designed that they will seal any size drill

holes between 38mm and 100mm, both sizes inclusive, at the specified level, and then be

capable of withstanding water pressures equal to the maximum grout pressure to be used at

that point without leakage.

Packers shall be suitable for all pressures and rock conditions at the Site and the most

appropriate packers shall be selected. Mechanically expanded packers may be used at the top

of the hole (for downstage grouting) but pneumatic or hydraulic packers shall be used where the

hole has to be sealed at depth.

4.7. Supply and Return Lines and Grouting Pipes, Hoses and Fittings

A single supply line shall be provided between each grout pump and the grout hole. A return line

shall be used for temporary clearing of hoses, for emergency pressure relief and to provide

accurate grout pressure control regardless of how small the grout take may be. Return lines

shall discharge into the mixer only. All supply and return lines shall be the shortest length

practicable for the particular grout hole being grouted.

All grout pipes, hoses and fittings shall be capable of withstanding twice the expected maximum

grouting pressure. All pumps and mixing equipment shall be housed in a central grouting station

that can be moved to another location when necessary and which is located such that the length

of grouting hose from the grout pump to the hole to be grouted does not exceed 300m. Where

the various individual elements of the plant are located in such positions that communication by

normal voice between the hole being injected and the plant is not satisfactory, the Contractor

shall install a means of verbal communication such as a radio, a telephone or a suitable signal

system to the approval of the Engineer.

4.8. Bentonite Mixers



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Where bentonite is incorporated in the grout, separate mixing tanks shall be provided in which

the bentonite/water mix can be prepared and kept agitated until required. Complete hydration of

the bentonite shall be achieved before incorporation in the grout.

4.9. Measuring Equipment for Trial Mixes

The Contractor shall provide adequate scales, balances and measuring flasks for making up

trial grout mixes of the chemical or suspension type.

5. CONSTRUCTION 5.1. General

(a) Supervision and Responsibility

Grouting shall only be performed in a workmanlike manner by competent and

experienced workmen. The Contractor shall submit details of the qualifications and

experience of the supervisors and operators he proposes to use to the Engineer for

approval before starting any grouting operation.

Modifications to the techniques specified in this specification or on the Drawings may

become necessary as work proceeds and as knowledge and experience is gained of the

natural rock and other foundation conditions. The Contractor shall alter or vary his

operations, after approval by the Engineer, or if directed by the Engineer, to suit such

knowledge and experience of the natural rock and other foundation conditions.

Grouting of the first three primary holes and subsequent splitting holes shall be used to

confirm the grout mixes, pressures and proposed grouting procedure.

Seven days before work commences on any grouting the Contractor shall submit to the

Engineer full details of the proposed methods of carrying out the work and also a detailed

programme indicating the proposed order of execution of the work. The approved or

agreed procedures and programme shall be strictly followed, and records shall be

accurately kept.

The Contractor shall take all steps necessary to ensure that no pollution is caused as a

result of drilling and grouting work. Before work commences the Contractor shall submit

details of the methods proposed to be employed to cope with grout spillages, which may

occur as a result of defective equipment, burst pipes or any other reason, for the approval

of the Engineer.

The Contractor shall adequately provide for the disposal of all wash water and waste

grout resulting from all grouting operations. Such water and grout shall not be allowed to

contaminate the Works and shall not be allowed to flow into any watercourse until it has

passed through settlement ponds or tanks approved by the Engineer.

No grouting shall be performed within a distance of 100m from areas where blasting is

still to be performed.

The Contractor shall give all facilities to the Engineer for inspecting the operations at all

times and for checking the results.

Unless otherwise approved all grouting which has been started shall be performed

without interruption until completed.

Regulation measurements and supervision of pressure shall be carried out continuously.

Pressure increases shall be controlled and the Contractor shall take care that the

pressure does not reach too high a value, keeping it within such limits as will ensure that

it does not cause cracking or deformation of rock or concrete. The Contractor shall be

entirely responsible for any damage which may occur due to the use of pressures in



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excess of the maximum allowable pressure for any particular stage as directed by the

Engineer.

Special treatment may be required for faults, seams, fissures or other specified features.

The Engineer shall give the appropriate instructions in each case.

Grout samples shall be taken from time to time as directed by the Engineer for the

purpose of performing density and strength tests.

(b) Records

The Contractor shall provide the Engineer daily, on an approved form, with accurate

records of all water testing and grouting operations performed the previous day.

The information recorded shall inter alia include :

(i) The reference number, location and stage of the hole grouted and grouting

methods employed.

(ii) The results of comprehensive and abbreviated water pressure tests, which shall

include the pressure and water absorption at regular intervals.

(iii) Details of the grout injection giving pressures, mix proportions, grout absorption at

regular intervals to be directed by the Engineer and the time at the start and end of

the grout pumping operating and indicating clearly the duration of stoppages.

(iv) General remarks on grouting processes adopted, surface leaks, interconnections,

refusals and any other phenomena that may have become apparent.

5.2. Drilling Grout Holes Grout holes shall generally be drilled with rotary percussion equipment in accordance with

Section 11A. Where specialised grouting methods are employed, the additional requirements of

Clause 11C.5.4 of this specification shall be complied with.

5.3. Standard Grouting Methods

5.3.1. General Procedure for Grouting

(a) Method

Downstage grouting methods with surface packers shall be used for all stages unless

conditions are such that grouting with the packer set at the bottom of the previous stage is

approved by the Engineer or that another method is approved or ordered by the Engineer.

Each stage of each grout hole shall be grouted only after having been satisfactorily

flushed and water tested in accordance with Section 11B, unless otherwise directed by

the Engineer.

(b) Flushing of Grout Holes

Grout holes shall be cleaned out by flushing before water pressure testing any stage or

section, or after grouting a hole or section of a hole in order to remove partially set grout.

Cleaning of holes after grouting shall not commence before at least 6 hours has elapsed

since the last injection of grout has been completed, or as ordered by the Engineer.

Flushing shall be conducted by inserting a suitable pipe or tube down to the bottom of the

hole and pumping in a mixture of air and water while moving the pipe up and down until

the wash water runs clear.

(c) Rinsing Grout Holes



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If, in the opinion of the Engineer the possibility exists that grout holes adjacent to the one

being grouted could become clogged, the Contractor shall continuously rinse such holes

with clean water while grouting is in progress in the adjacent hole or for such other time

as the Engineer may direct. The Contractor shall rinse all holes that could become

clogged due to the ingress of grout from adjoining holes, as is evidenced by the

emergence of grout or washing water from such holes. In the event of such holes

becoming clogged the Contractor shall clear such holes or replace them with such new

holes as the Engineer may direct.

Rinsing shall be conducted by inserting a suitable pipe or tube down to the bottom of the

hole and pumping in sufficient clean water to produce an upward velocity of the water in

the hole of at least 1m/s.

(d) Protection of Filters and Drains

Unless otherwise authorised by the Engineer, no grouting shall be performed within 50m

of installed perforated pipes or gravel filters. Where permitted in such locations, the

Contractor shall maintain a flow of water through the drains likely to be affected. Where

leakage of grout into drains does occur, the Contractor shall immediately stop the grouting

operations and shall remove all grout from the drains affected by rinsing, to the

satisfaction of the Engineer. Such stoppage of grouting operations and rinsing of drains

shall be repeated as often as required.

(e) Starting Mixes and Thickening

If water pressure tests indicate a tight hole, grouting shall be started with a thin mix. If an

open hole condition exists grouting shall be commenced with a thicker mix with the rate of

grout injection at all times as uniform as is practicable. The water : solids ratio shall be

varied according to the conditions encountered such that the rate of absorption of solids is

a maximum at all times. Periodic applications of water under pressure shall be made only

if necessary to prevent premature stoppage. Under no circumstances shall the pressure

or rate of grout injection be suddenly increased as either may promote stoppage.

Should it prove impossible to attain the required pressure with the approved grout

consistency, the grout shall be gradually thickened up by adding cement while injection

continues at a constant rate until the required maximum pressure is attained.

The Contractor's proposed starting mix and thickening procedure shall be submitted to

the Engineer for his approval for each stage of each hole being grouted.

(f) Abnormal Takes

If a hole absorbs an abnormal amount of grout (more than 100kg of cement per metre

length of hole unless otherwise indicated by the Engineer) without reaching refusal or

without showing any reduction in grout take, the Contractor shall inform the Engineer

immediately to enable him to determine the procedure to be followed in dealing with the

situation. The rate of injection shall be reduced or injection carried out intermittently or

grout thickened or any other procedures ordered by the Engineer shall be adopted.

(g) Pressures

The injection pressure shall be measured and controlled at the collar of each hole with the

return line being used for temporary circulation in the hoses to avoid clogging and for

pressure control as indicated in Clause 11C.4.7 of this specification.

The pressure used for grout injection may vary with the conditions encountered. The

pressures shall be as high as practicable but shall be limited so that grout is not wasted



172

by leakage through the rock surface and so as not to cause displacement of the rock or

structure. Grouting pressures shall be as shown on the Drawings or ordered by the

Engineer. Should any movement of the rock or structure be observed during grouting

operations, the pressure in the hole shall immediately be released.

The maximum starting pressure for any new application shall be kept at 50kPa or lower

for at least 5 minutes during which the connections, possible rock movements and leaks

shall be closely observed. Only if no leaks or rock movements are experienced shall the

pressure steadily be increased during the next 25 minutes to the pressures indicated on

the Drawings or ordered by the Engineer.

Grout mix proportions shall be adjusted as necessary and as approved by the Engineer to

prevent any rapid build-up of pressure.

(h) Completion of Grouting

The grouting of any hole or stage of hole shall not be considered complete until that hole

refuses to take any grout whatsoever during a 15-minute interval at the maximum

pressure required for that stage and at the particular water : solids ratio indicated by the

Engineer.

After the grouting of any stage of a hole is complete the pressure shall be maintained by

means of a stopcock or other suitable device until the grout has taken its initial set and

shall be closed for at least 6 hours from the last application of grout in the hole. Unless

otherwise ordered by the Engineer, all the grout shall then be flushed from the hole by

means of a high pressure air and water jet until the wash water runs clear. If any stage of

a hole has to be re-drilled due to failure of the Contractor to remove the partially set grout,

such hole shall be re-drilled by the Contractor at his own expense.

(i) Interruption

If the grouting of any hole is interrupted for any reason, the Contractor shall immediately

clean the hole being grouted and any adjacent holes into which grout has entered by

flushing.

(j) Final Plugging of Grout Holes

Final plugging of grout holes shall generally not be performed until 48 hours after

completion of grouting of the final stage or section of a hole, and not until the approval of

the Engineer has been obtained, upon which the holes shall be filled with cement mortar

consisting of 1 : 0,75 mixture of cement and water or other of approved consistency and

composition from the bottom upwards so that all the water is replaced by grout.

Prior to plugging of grout holes the Contractor shall ensure that no hole becomes blocked

by any cause whatsoever.

(k) Removal of Standpipes and Casings

On completion of all grouting work on a hole, standpipes and casings shall be removed or

cut off at the ground or other surface to the satisfaction of the Engineer. All voids existing

after either procedure shall, as directed by the Engineer, be made good by grouting up

the hole as specified in the foregoing paragraph (j).

Where a portion of a hole is in overburden which may or may not have a casing, that

portion situated in the overburden shall be similarly treated.

(l) Making-good Holes in Finished Concrete Surfaces



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Where grouting is specified to be done from any finished concrete surface with thickness

not exceeding 2m, the holes shall be caulked up on completion of grouting. Where the

concrete thickness exceeds 2m, the holes shall be plugged as specified in the foregoing

paragraph (j).

Permission to caulk the holes shall be obtained from the Engineer before proceeding. The

holes shall be caulked to a minimum depth of 50mm from the surface of the hole. A

method approved by the Engineer shall be employed to caulk the hole, using a very dry

mix comprising 1 part cement and 2½ parts sand measured by weight.

(m) Construction of Grout Caps

Grout caps shall be constructed as shown on the Drawings in those areas directed by the

Engineer. No blasting shall be used for excavating grout caps except if approved by the

Engineer and only under such conditions as he may approve from time to time. Over-

excavation for the grout caps shall be kept to a practical minimum. Weak zones

intersecting the grout cap excavation shall be excavated as directed by the Engineer.

(n) Cleaning Operations

During grouting operations the Contractor shall take all precautions necessary to prevent

drill cuttings, equipment exhaust oil, wash water and grout from defacing or damaging the

permanent structure. The Contractor shall furnish such pumps as may be necessary to

handle waste water and grout from the grouting operations and shall, upon completion of

this portion of the work clean up all waste resulting from his operations, that is unsightly,

that may cause pollution or would interfere with the efficient operation of the Works.

5.3.2. Specific Procedure for Curtain Grouting

The spacing, diameter and depth of the primary holes shall be as shown on the Drawings or

directed by the Engineer.

(a) Downstage Grouting

Unless otherwise directed or approved by the Engineer the procedure for curtain grouting

shall be on the basis of downstage grouting.

Generally a grout curtain shall be formed by drilling primary holes at 8m centres or such

other spacings shown on the Drawings and in stages, as indicated on the Drawings, all of

which shall be flushed and water tested according to Section 11B and then be grouted

using downstage grouting and following the general procedure set out in Clause

11C.5.3.1 of this specification. Unless otherwise directed by the Engineer a secondary

series of holes shall then be drilled along the same line as the primary holes with the

secondary holes placed midway between the primary holes. After the secondary holes

have been drilled, water tested and grouted as necessary for a particular stage, zones

where a third (tertiary) or fourth (quaternary) series of splitting holes may be necessary,

shall be drilled as directed by the Engineer. Generally a splitting hole shall be drilled

where a water loss in excess of 2 Lugeon has been obtained.

The first stage of all grout holes shall generally be drilled to a depth of less than 10m into

the rock foundations, or as directed by the Engineer. The depth of the successive stage

shall be as shown on the drawings, or as directed by the Engineer, but shall generally not

exceed a depth of 18m. In areas where the grout curtain does not exceed a depth of 10m,

grouting shall be performed in a single stage only.

Drilling of a successive stage shall not be commenced until all drilling and grouting of the

upper stage between the primary holes within at least one primary hole spacing adjacent

to the hole to be deepened has been completed to the approval of the Engineer. As a

general rule, it means that drilling/grouting must stay one completed stage behind



174

previous holes. All successive stages shall be drilled and grouted in the same order as

the first stage. The number of holes between primary holes shall be determined by the

split spacing method between each pair or primary holes and for each stage being drilled

and grouted.

A curtain grout hole shall not be drilled until all consolidation grout holes within a distance

of 10m from the particular curtain grout hole have been finally grouted.

In general, surface packers, seated into solid rock or concrete, shall be used. However,

where it is found that grout from lower stages "breaks back" through a previously grouted

stage or where there is excessive surface leakage of grout or where it is found impossible

to build up a grout pressure, the Engineer may direct the Contractor to position packers

such that only a specific stage of a hole is grouted separately.

After grouting any stage of any hole it shall be cleaned by flushing as described in Clause

11C.5.3.1 of this specification, except when the Engineer directs that the grout be left

undisturbed to harden before then being re-drilled and flushed. No drilling of a further

stage shall be performed until a period of at least 24 hours has elapsed after grouting the

previous stage. Drilling, flushing, water pressure testing and grouting of successive

stages shall be performed until the specified depth of grout curtain is reached.

All stages of grout holes drilled shall generally be grouted after being water pressure

tested irrespective of the results of the water pressure tests, unless otherwise directed by

the Engineer.

Before drilling the next stage of a particular hole, the Contractor may be instructed to

perform an abbreviated water test on the stage(s) previously grouted. If the water loss of

the particular section exceeds 1 Lugeon (after grouting), such stage(s) shall be regrouted

before commencing drilling of the next stage, unless otherwise directed by the Engineer.

After completion of the final stage the hole shall be flushed in accordance with Clause

11C.5.3.1 of this specification and if ordered by the Engineer, the full length of the hole

shall be subjected to an abbreviated water pressure test conducted prior to finally

plugging the hole. Should the water loss exceed 1 Lugeon the hole shall be regrouted as

directed by the Engineer.

The Engineer may order the drilling of a check hole(s) to determine the effectiveness of a

grouted section. Such check hole shall be drilled and comprehensive water pressure tests

performed according to Sections 11A and 11B. If the water loss in the check hole

exceeds 2 Lugeon, the hole shall be grouted according to Clause 11C.5.3.2(b) and if the

water loss is less than 2 Lugeon, the hole shall be plugged according to Clause

11C.5.3.1.

If during the grouting of a hole, communication is established with a neighbouring hole,

the Engineer may instruct that rinsing of the neighbouring hole be dispensed with and that

the hole be grouted immediately. In such instances the point of entry of grout into the hole

shall immediately be determined by means of a packer. The hole shall then be sealed off

with the packer positioned just above the highest point of entry and grouting of the

adjacent hole shall be continued at such reduced pressure as may be dictated by the

level of the packer closest to the surface. The Contractor shall provide for making

simultaneous grout connections to a series of grout holes if during the pressure testing

operations it becomes evident that a considerable flow of grout would occur between

such holes and if the Engineer directs that such holes be grouted simultaneously.

When grouting holes near the surface of the foundations the Contractor shall, if any

substantial leaks of grout occur through cracks and fissures in the foundations, take

whatever measures that may be necessary, such as caulking, to stem the grout flow and

prevent the loss of grout. The pressures used for grout injection near the surface of the

foundations shall be as indicated on the Drawings or directed by the Engineer, but shall



175

be varied to suit the conditions encountered and shall be as directed or approved by the

Engineer. In general the upper stages shall be grouted at a low pressure and the deeper

stages at a higher pressure. The pressure shall generally be as high as possible but shall

be limited so as not to cause displacement of rock or concrete.

(b) Upstage Grouting

Unless otherwise approved by the Engineer, upstage grouting shall generally only be

employed when check holes, which were drilled to examine the effectiveness of the

curtain grouting operations, need to be grouted.

When employing upstage grouting the holes shall be grouted from the bottom up and the

lengths of the sections (stages) to be grouted shall be as approved or directed by the

Engineer. The packer shall be lowered to the top of the section to be grouted and the

Contractor shall take such precautions as may be necessary to ensure an adequate seal

and to prevent grout that may leak past the seal from causing the packer to stick in the

hole.

After the grout has taken its initial set the packer shall be removed and the hole flushed

as described in Clause 11C.5.3.1 of this specification. The packer shall then be inserted

at the next level and then the full length of the hole below the packer shall be grouted.

This procedure shall be continued until the hole has been grouted over its full length.

Immediately prior to the final plugging of a hole grouted by means of upstage grouting,

and if directed by the Engineer, abbreviated water tests using a double packer shall be

conducted on each section of the hole grouted, using a water pressure of 100kPa

measured at the collar of the borehole. If the rate of water loss exceeds 1 Lugeon for any

section tested, the Contractor shall regrout such sections of the hole and at such

pressures as the Engineer may direct.

5.3.3. Specific Procedure for Consolidation Grouting

Consolidation grouting shall be carried out by drilling and grouting groups of holes, at the

spacings and positions within the foundation area of the concrete structure and to the depths

into the rock as shown on the Drawings or as directed by the Engineer. Unless otherwise

directed by the Engineering, all drilling, water pressure testing and grouting shall be performed

in a single stage operation.

The grouting procedures and injection pressures shall in general be as indicated in

Clause 11C.5.3.1 of this specification, unless otherwise directed by the Engineer. Each group of

consolidation grout holes shall be grouted only after being satisfactorily flushed and if directed

by the Engineer, water pressure tested (abbreviated) in accordance with Section 11B.

The sequence of drilling and grouting the consolidation grout holes shall be as shown on the

Drawings or as directed by the Engineer. Grouting shall generally be done from the outer holes

towards the centre of the foundation area to be grouted.

Unless otherwise directed or shown on the Drawings, consolidation grout holes within 10m from

any curtain grout holes to be drilled shall have been completed before drilling the curtain grout

holes.

5.4. Specialised Grouting Methods

5.4.1. General

The Contractor shall use specialised grouting methods such as the Tube-a-manchette (TAM)

grouting method, or other method approved by the Engineer, if directed by the Engineer in areas

where:



176

a) the standard grouting procedures specified in Clause 11C.5.3 of this specification prove to

be ineffective, or

b) where joints in the concrete or the concrete/rock contact need to be grouted.

5.4.2. Tube-a-manchette (TAM) Grouting Method

The TAM grouting method comprises a perforated tube which is sealed into the ground with a

relatively weak cement/bentonite sleeve grout. Rubber sleeves covering the perforations shall

be fitted around the outside along the length of the tube. The sleeves shall act as one-way

valves to allow grout to rupture the sleeve grout and enter the ground, but preventing the re-

entry of the grout by closing onto the tube once the injection pressure has dropped.

The Contractor shall submit a detailed proposal concerning the TAM grouting to the Engineer for

prior approval.

Drilling shall be performed according to Section 11A of this specification. Positions of the grout

holes shall be determined by the Engineer.

The sizes of the boreholes shall be as approved by the Engineer and shall be large enough for a

TAM having an inner diameter of approximately 50mm to 70mm to be installed in the borehole

with the annular space sufficiently wide to ensure good embedment of the tube and the sleeves.

The TAM shall be made of uPVC tubing and shall be assembled on Site to the lengths required

for each borehole. The TAM shall be installed in the borehole and the annular space between

the TAM and the ground shall be grouted with a special grout mix consisting of a dense cement

mix containing a small percentage of bentonite to be determined experimentally on Site. If a

casing is present, it shall be pulled out as the sleeve grouting proceeds, leaving the TAM

properly embedded.

After the sheath grout has been allowed to set, grouting of the formation shall be done by using

a double packer at each sleeve. The packers shall be either normal leather cup packers or

inflatable packers.

The sequence of grouting and the pressures used shall be determined by the Contractor on Site

and be to the approval of the Engineer. The grout material and the grout mix proportions shall

be as directed by the Engineer. Cementitious grout shall generally be used for the first

application to fill major voids after which the Engineer may instruct the use of lower viscosity

chemical grouts. Complete records of water acceptances and grout takes shall be kept by the

Contractor, to enable the Engineer to detect where further injections are required.

The tubes shall be cleaned by flushing and shall be capped after completion of the grouting

operation leaving the TAM fully accessible for testing and/or regrouting at a later stage if so

directed.

TAM grouting may also be done from pipes/sleeves embedded in the concrete.

6. TOLERANCES

Not applicable.

7. TESTING

The Contractor may be requested to provide approved Marsh flow cones, thermometers, mud

balance and measuring cylinders (60mm diameter) to enable the Engineer to check the

consistency of the grout at any time. The applicable limits shall be jointly established by

laboratory and field tests prior to work commencing.

7.1. Density (Mud Balance)



177

Determination of the relative density of freshly mixed grout shall be with a mud-balance.

Reading of relative density taken directly from the calibrated beam shall be converted to a water

cement ratio by means of an agreed curve or table.

7.2. Viscosity (Marsh Cone)

The fluidity of grout shall be measured with a flow cone, immersion apparatus or viscometer.

The instrument shall be accurately calibrated in a laboratory so that the specified viscosity of the

grout can be controlled satisfactorily.

The procedure for conducting the flow-cone test for measuring the fluidity of grout shall be as

follows:

The type of flow shall be subject to the approval of the Engineer.

Immediately after the grout has been mixed, the pre-wetted flow cone, which is held firmly with

its top rim in a level position, shall be filled with grout to the level indicated by the pre-set pointer,

whilst the bottom orifice is held closed with a finger.

As soon as the required volume of grout (± 1 750mℓ), is reached, the finger shall be released to

allow the grout to flow out freely through the bottom orifice. A stop watch shall be used to

determine the flow time for emptying the cone, to the nearest second.

The readings obtained during grouting shall be compared with the times determined in the

laboratory for grouts of the specified viscosities.

7.3. Bleeding

The bleeding of grout shall be measured in a metal or glass container with an internal diameter

of approximately 100mm and a height of approximately 120mm. The grout and water levels in

the container shall be controlled with a metal bridge into which two adjustable studs A and B are

secured.

The procedure for determining the bleeding of grout shall be as follows:

Studs A and B in the metal bridge shall be adjusted and locked so that the distance from the

lower tips of the studs to the bottom of the container will be approximately 100mm and 107mm

respectively. The volumes VAand VB for the container at the respective levels of the stud settings

shall then be determined to the nearest millilitre.

The container shall be filled with freshly mixed grout to a level where the grout will just touch the

tip of stud A which points downwards. The bridge shall then be removed and the container

tightly sealed to prevent evaporation. The container shall then be stored at 20°C and kept free

from vibrations for the entire duration of the test.

Three hours after the grout has been mixed, the container shall be opened and the free (bleed)

water poured off. The bridge shall be placed over the container with the tip of stud B pointing

downwards and water poured onto the grout with a measuring apparatus until the water level

touches the tip of stud B. The volume of water added shall be determined to the nearest millilitre and designated as .

The percentage of bleeding shall be calculated from the formula.

7.4. Test Cubes

If requested by the Engineer, samples of grout shall be taken by the Contractor at the point of

mixing or of deposition as instructed by the Engineer and in the presence of a representative of

the Engineer, all in accordance with the sampling procedures described in SANS 5862.



178

Samples shall be taken on the basis of one for each 50m³ of grout pumped but in any case not

less than one sample per day per mixing station.

The Contractor shall cast from each sample, cure and test six test cubes as set out in

SANS 5863. Three cubes shall be tested at 7 days and 3 at 28 days.

The average strength of the 3 cubes crushed shall be referred to as one test result.

Grout shall be deemed to comply with the strength specified if the average strength of any 4

consecutive test results exceeds the agreed characteristic strength by 2MPa and the strength of

any test result is not less than the specified characteristic strength minus 3MPa.

8. MEASUREMENT AND PAYMENT 8.1. General Principles

Specific items such as percussion drilling, casings and standpipes shall be measured according

to Section 11A. Water pressure testing of boreholes shall be measured according to

Section 11B. Materials used in the permanent works shall be classified according to their nature

and usage and generally measured by mass of the dry materials.

The Contractor shall at his own expense, replace by another drilled hole any grout hole that is

lost or damaged due to mechanical failure of equipment, the grouting in of packers or the

inadequacy of grout supply, clear or replace all grout holes that become clogged due to the

ingress of grout from nearby grout holes and redrill any hole that is lost due to failure of the

Contractor to timeously remove partially set grout.

8.2. Scheduled Items

8.2.1. Grout Connections to Drilled Holes Unit: litre (ℓ)

The number of connections to drilled holes for grouting purposes shall be measured. Grout

connections shall be measured once only for each stage or section of hole unless the Engineer

orders the grouting equipment to be removed and subsequently set up again. The rate shall

include for the supply and installation of packers, other equipment and labour.

8.2.2. Grouting Unit: litre (ℓ)

The grout volume for payment shall be measured by the volume of grout that was pumped and

injected. The rate for payment shall include for mixing of the grout, keeping of grout records,

flushing of holes to remove partially set grout, for cleaning operations and any caulking required.

The rate shall include for removing any standpipes and casings as specified in Sub-clause

11C.5.3.1(k) and final plugging of the holes as specified in Sub-clause 11C.5.3.1(j).

No distinction between downstage and upstage grouting shall be made.

The grouting materials shall be measured for payment under Clause 11C.8.2.3.

8.2.3. Materials used in all Grouting Operations

8.2.3.1. Cementitious material Unit: tonne (t)

The weight of cementitious material actually used in the grouting operations shall be measured.

The rate for payment shall include furnishing and batching and screening. Grout that was lost as

a result of failure of equipment or on account of the Contractor's failure to comply with the

requirements of this specification or which was rejected by the Engineer as being unsuitable for

use in grouting operations, including grout that has not been injected within 2 hours after mixing

and has subsequently been disposed of, shall not be measured for payment.

Distinction between different kinds of cementitious materials as scheduled shall be made.



179

8.2.3.2. Sand Unit: m³

The volume of sand used in the grouting operation shall be measured separately in the dry.

8.2.3.3. Additives Unit: litre (ℓ)

The mass of additive scheduled or ordered by the Engineer shall be measured.

The rate for payment shall cover all costs of including the additives in the grout mix.

8.2.3.4. Chemical grouts Unit: kg

The mass of chemical grouts before mixing shall be measured. The rate shall cover all costs for

handling, batching and mixing.

8.2.4. Grout Cap Unit: m³

The cubic metres of concrete needed to form the grout cap shall be measured. The rate shall

include the cost of all materials and plant required for excavating for the cap, mixing and placing

of the concrete, formwork and casting in of any standpipes or casings where ordered.

Standpipes or casings shall be measured for payment in accordance with Section 11A.

8.2.5. Rinsing drilled holes Unit: h

The number of hours of rinsing of drilled holes that the Engineer has ordered to prevent clogging

during the grouting operation shall be measured. Rinsing of a portion of a hole above a packer

while injecting grout shall not be measured for payment.

8.2.6. Tube-a-manchette (TAM) grouting Unit: litre (ℓ)

The grout volume for payment shall be measured by the volume of grout that was injected. The

rate for payment shall include for mixing of the grout, keeping records, flushing the pipes, supply

and installation of TAM pipes, cleaning operations and caulking required. No additional payment

for connections to grout pipes will be made.

Extra over payment items shall be scheduled for regrouting of TAM pipes.

8.2.7. Density (Mud Balance) Test Unit: No

The rate shall cover all the costs to carry out and complete grout density tests as ordered by the

Engineer according to Clause 11C.7.1.

8.2.8. Viscosity (Marsh Cone) Test Unit: No

The rate shall cover all costs to carry out and complete grout viscosity tests as ordered by the


8.2.9. Bleed Test Unit: No

The rate shall cover all the costs to carry out and complete grout bleed tests as ordered by the


8.2.10. Test Cubes Unit: No

The rate shall cover all the costs for sampling, curing and crushing six test cubes, including

recording and providing test records according to Clause 11C.7.4 as ordered by the Engineer.

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