specification for construction of manholes,

7/27/2019 Specification for Construction of Manholes,

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Specification for Construction of manholes, Joint Box and Laying of Ducts

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SPECIFICATION FOR CONSTRUCTION OF MANHOLES,

JOINT BOXES AND LAYING OF DUCTS

1.0 GENERAL

This section of the Specification describes and specifies requirements

for the supply, delivery, installation, testing, commissioning,

handing over in approved working order and maintenance during the

Defects Liability Period of the manholes, joint boxes and ducts all in

accordance with the Specification, Supplementary Notes, Bill of

Quantities, Conditions of Contract, Drawings etc.

2.0 STANDARDS AND APPROVAL

The installation works shall comply with the latest relevant British

Standard Specification and Syarikat Telekom Malaysia Berhad (STM)

specification and requirements. All material used shall be of thetypes approved by STM and acceptance by the S.O.s Representative.

Samples of materials shall be submitted to the S.O.s Representative

for approval prior to installation. Sample of the materials which have

been approved by the S.O.s Representative for use in the Works shall

be displayed at the site office for reference.

3.0 WORK PROGRAMME

The Contractor shall submit to the S.O.s Representative detail work

programme for approval within two weeks after acceptance of tender of

such shorter period as required by the S.O.s Representative. If the

work programme submitted is not acceptance by the S.O.s

Representative, the Contractor shall amend and resubmit the programme

for final approval.

4.0 SITE DIARY

The Contractor shall keep at the work site a site diary, to which the

S.O.s Representative shall have access at all times during working

hours. The Contractor shall keep the site diary posted up to date,

entering therein all measurements on the day on which they are taken

and details of any deviations or extra work. Records of works shall be

submitted daily to the S.O.s Representative for verification. All

entries in the said shall be considered to be, and shall remain, theproperty of the S.O.s Representative.


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5.0 SAFETY

Adequate approved traffic warning signs and lamps shall be provided

and displayed by the Contractor at all time. The form, placing and

light of the warning signs must comply with all local and national

regulations and safety codes for road works. The Contractor shall take

all necessary precautions and follow the correct procedures to avoid

accidents due to presence of explosive gases, asphyxiating gases and

toxic gases in the underground network. The Contractor shall take all

necessary measures to ensure the safety of the workmen, members of the

public, plant or property, especially when carrying out any works in

manholes or joint boxes.

6.0 QUALITY OF MATERIALS

6.1 CONCRETE

Concrete shall be of quality A,B,C,F or G as provided by this

Specification and the proportions of the ingredients shall be as

follows :-

Concrete

Mixture

Parts by Measure

Cement Sand Aggregate

Usage

Quality A

Quality B

Quality C

Quality F

Quality G

Cement

Mortar

1 2 4

1 2 7

1 3 9

1 2 3

1 1 3

1 4 3

1 3 -

All Jointing

Chamber, Plinth.

Placed between

two sets of plant

if separation

clearance is

152mm or less.

For supporting

protecting or

filling in

purpose.

Concrete Troughs.

Filling in

Manholes covers

3E & 7E.

Encasement of

Ducts.

Dummy ducts in

jointing chamber,

repairing damaged

or split ducts.

The concrete used for encasing ducts shall be relatively dry and

having the consistency of wet sand. In no circumstances shall the

water content be increased appreciably as this will result in a weak

concrete. The cement used for encasing ducts shall be rapid-hardening

type.


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Concrete mixing shall be done manually or by machine. Ready mixed

shall be the first preference if available. In the process of mixing

the concrete, the ingredients shall be repeatedly turned over and

mixed in a dry state on mixing boards, after which water from the nose

of a watering can shall be added and the materials shall than again be

turned over sufficiently to ensure thorough mixing. The mixing boards

shall be sufficiently large to give ample room for turning over the

ingredients entirely from one place to another and shall be so

arranged or constructed that liquid cement shall not escape through

the joints. When mixed by machine the water shall be poured in first

and the ingredients shall be put into the machine dry without prior

mixing.

The standard of cleanliness of water for mixing is that it shall be

fit for drinking. The quantity used shall be sufficient to effect the

proper hydration of cement to obtain a plastic mixture. The S.O.s

Representative may reject concrete which is, in his opinion, so over

watered that it would be deficient in ultimate strength.

The concrete shall be deposited carefully in its intended position as

quickly as possible after being mixed and all concrete footings and

foundations shall be tamped and carefully leveled. All concrete shall

be compacted by the used of a poker type vibrator until a dense solid

mass without voids is obtained. Under no circumstances must the

vibrator be used longer than is necessary to obtain compaction nor

left unattended in the concrete, otherwise segregation of the mixture

will occur.

Concrete which has become hard, dry, dirty or not placed within 30

minutes after being mixed shall not be used, and of any earth fall on

top of any concrete after laying and before the work is completed, it

shall be carefully removed.

6.2 CEMENT

All cement used shall comply with the relevant British Standard

Specification. The cement shall be fresh, fine, smooth, loose and warm

and the S.O.s Representative reserves the right to reject the cement

which is found unsatisfactory. The Contractor may employ generally

rapid hardening Portland cement or high alumina cement in lieu of

ordinary Portland cement for his convenience and acceleration of

progress. Before high alumina cement is used, all tools and plants

shall be cleaned. High alumina cement shall not be used with P.V.C.

ducts. The Contractor shall ensure that all cement is protected

adequately against moisture while being transported and stored. Theused of cement aids where an additive is added to ordinary Portland

cement to render it rapid hardening is not recommended and permission

for its use shall first be obtained from the S.O.s Representative who

shall also determine the amount of additive to be used.


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6.3 SAND

All sand to be used shall be river sand. It shall be clean, sharp,

gritty and free from loam or other impurities. If the sand is found to

contain more than 5 percent by volume of silt, the sand shall not be

used. The sand used shall be course and the grains graded in size to 5

mm.

6.4 AGGREGATE

The aggregate for concrete shall be cleaned screened river ballast,

gravel, stone or other materials as approved by the S.O.s

Representative. The aggregate shall be of the nature of cubes, not of

flakes and graded in size and free from dirt, floury stoned duct,

loam, earth or any other impurities. Clinkers, brick sandstone or

other porous stone shall not be used.

The maximum size of aggregate for each of the qualities of mixtureincluded in Section 6.1 shall be as follows :-

A ..20mm, B40mm, C..any size suitable for work, F&G 10mm, for

encasement of ducts .6mm. Any portion which will pass a 5mm mesh

shall be used as sand.

6.5 BRICKS

The bricks used shall be best quality hard burned common bricks,

either wire cut or plastic pressed, or selected hard hand-made, stock

bricks or other hard or over-burned hand-made bricks of comparable

quality. They shall be of good shape, free from visible particles or

lime and from serious cracks, and shall not absorb more than 12

percent of their weight when immersed in water for 24 hours. Five

bricks from each batch delivered at site shall be tested and all shall

be required to pass the test. The dimensions of bricks described as

type 2 and 3 in B.S. 657 shall be regarded as standard.

6.6 CEMENT MORTAR

The cement mortar shall consist of one measure of cement and three

measure of sand. The materials after being gauged shall be thoroughly

mixed in a dry state and then thoroughly mixed with sufficient water

to form a stiff mortar. Water, cement and sand shall not be added

after mortar has one been mixed and set. If mortar has once begun toset and excess water has been used for mixing, further quantity of

sand and cement not be added but the whole mortar shall be rejected.


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6.7 STEEL, IRONWORK AND HARDCORE

All structural steel shall be in accordance with British Standard

Specification. All invoices for steel shall be inspected by the S.O.s

Representative.

If the Contractor cannot procure such reinforcing steel in the

Imperial sizes as described in the Drawings but can obtain such steel

in the Metric sizes and the dimensions approximating to those in the

following table, then the Contractor shall forthwith obtain the

approval of S.O.s Representative before such steel are ordered.

Imperial size (ins) 5/16 3/8 5/7 7/8

Metric size (mm) 6 8 10 12 16 20 22

Imperial size (ins) 1 11/8 1.25 1.5

Metric size (mm) 25 28 32 40

Bolts, nuts, rivets and other accessories shall be in accordance withthe relevant British Standard Specification. All invoices for iron

shall be inspected by the S.O.s Representative. All hardcore shall

consist of hard brick, concrete or stone graded down to a minimum of

80mm. Sufficient hardcore material under the sizes of 80mm shall be

added up to fill voids and aid consolidation.

7.0 EXCAVATION

The Contractor shall carefully segregate the surface and foundation

material from the lower sub-soil. Sub-soil shall be protected whilst

above ground from weathering action which could cause a damaging

increase in the natural moisture content of soil leading to the

formation of voids and/or settlement after back-filling. Sub-soil

which is damages shall be removed and replaced by undamaged sub-soil.

Except where otherwise provided, the excavation shall include all

necessary/timbering and shoring.

Mechanical excavator shall be used in a manner as to fulfill the

requirements of excavation work. A timber base support or platform

shall be placed under the fees of the excavation machine as a

protection to prevent the carriageway surface being marked when the

machine is in operation.

Pneumatic drills or other power driver appliance shall be fitted with

efficient silencing devices and the compressor machine shall be

maintenance in an efficient condition so as to avoid undue noise.

The Contractor shall obtain prior approval of the S.O.s

Representative to dig pilot holes and excavation of trenches. Pilot

holes shall be dug at positions selected by the S.O.s Representative,

normally one per sectional length to ascertain the most suitable

position for the work.

Timber support for excavation shall be so designed and placed as to

permit wherever possible withdrawal of such timber and consolidation

of the space it occupied.


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____________________________________________________________________________________________The routes of the trench shall be marked out and approved by the

S.O.s Representative before excavation. The width of trench excavated

shall not be greater than is necessary for satisfactory execution of

the work. The routes of the excavated trench shall be as straight as

possible and any bends or curves shall be of the maximum radius

possible. Where ducts are to be encased in concrete the width of

trench shall be dependent upon the number of ducts to be laid in a

horizontal direction. In unstable ground, timbering shall be used to

support the trench and to act as a former for the concrete.

The depth of trenches shall comply with the specification and as

directed by the S.O.s Representative. The floor of the trench shall

be leveled and shall not follow surface irregularities. The bottom of

the trench shall be normally leveled with 50mm of sand and rammed.

In passing from footway to carriageway and vice versa or where ducts

enter jointing chambers below standard depth or in any other

circumstances where it is necessary to change level, the bottom of the

trench shall rise or fall gradually as directed by the S.O.s

Representative.

The Contractor shall dispose of the water in the trench so as to

prevent any risk of the ducts, cables and other materials to be laid

in it being detrimentally affected. He shall provide all pumps and

appliances required and shall carry out the necessary pumping and

bailing.

8.0 DUCTS LAYING

8.1 GENERAL PROCEDURES

The routes of ducts shall be kept as possible. In the case of 4-ways

ducts or more, the lines shall break joint by approximately half the

duct length in alternative lines, horizontally and vertically.

Unless otherwise permitted by the S.O.s Representative, no ducts

shall be laid and covered up in the absence of the S.O.s

Representative.

All ducts laid direct in the ground shall be kept well clear of water

mains, service pipes, sewers, subways, manholes, joint boxes etc.

belonging to others. In order to permit the use of tapping machine

on water mains, a minimum clearance of 152mm shall be given wherever

possible. This clearance shall also be given, if practicable, to the

other service mentioned above. In no case shall the clearance be less

than 25mm, where the two services cross each other, the minimum

vertical clearance shall be 50mm.

The following minimum separating distance between the electrical

supply cables and lines of ducts shall be provided :-

(a) High-voltage single-core cables (exceeding 650 volts)Standard minimum clearance .460mm

No exception to this requirement will be permitted.

(b) High-voltage multi-core cables (exceeding 650 volts)


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____________________________________________________________________________________________Standard minimum clearance . 300mm

If difficult cases a reduced clearance shall be permitted. Where

it is impossible to provide a greater clearance than 150mm, a

layer of quality B concrete, not less than 50mm thick and of a

width to overlap the electrical services by 50mm on each side,

shall be placed between the two services. Where the two service

cross each other, the length of the layer of concrete shall not

be less than the width of the telephone services.

(c) Low and medium-voltage cables (not exceeding 650 volts)

Standard minimum clearance .50mm

Where the two services cross each other no exception to this

requirement shall be permitted. At other points a clearance down

to 25mm shall be allowed in difficult cases. Wherever the

clearance is 50mm or less, the spare between the two services

shall be filled with a layer of quality B concrete.

In all cases the concrete shall overlap the electrical services by

50mm on each side, and at crossing, the length of the layer of

concrete shall nor be less than the width of the telephone services.

The Contractor shall cut and bend the ducts according in the

requirements of the work. Inside edges of cut ducts shall be

thoroughly rounded off to prevent damages to cables from the edges.

The trench bottom shall be filled with a layer of sand 50mm thick and

holes shall be taken out of the bottom of the trench at all points

where sockets occur so that the barrels of the ducts rest on solid

ground. In rocky soils, the trench shall be bedded with 80mm thick

sand on which the ducts are laid.

On completion of the ducts line between any two jointing chambers of

sites, a cylindrical brush connected to the following end of a mandrel

shall be passed twice through each way to clean the duct and to remove

any foreign matter which may have entered.

All test shall be carried out in the presence of the S.O.s

Representative. If any obstruction or other defect be discovered, it

shall be rectified to the satisfaction of the S.O.s Representative.

A hardwood plug shall be inserted at the ends of each way in a line of

ducts until the length has been tested and passed.

When jointing chambers are provided on an existing duct routes or when

any disturbance takes place which may affect the alignment of the

ducts, a test mandrel of appropriate dimensions shall be drawn through

each of the spare ways. The Contractor shall take all reasonable stepsto prevent damage to the paving by his plants.


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____________________________________________________________________________________________8.2 GALVANISED IRON PIPES

All galvanized iron pipes shall comply with STM Specification Lines D

0010. Galvanized iron pipes shall be provided in nominal lengths of 6m

and provided with screwed socket at one end.

The procedures of laying galvanized iron pipes shall be as specified

in Section 8.0. Where one line of ducts is laid over the lower line of

ducts and carefully rammed to form a bedding of 50mm in thickness for

the top ducts. Sand shall also be rammed between the ducts laid said

by side in the same trench. The ducts shall break joint by

approximately half the length in alternative lines, horizontally and

vertically.

Joints shall be made by positioning the threaded end of the pipes to

the screwed socket of the other pipe end. One of the pipes shall be

turned until it cannot be turned any more and the thread of the

threaded end cannot be seen.

Pipes shall be cut where necessary at right angle to the bore only.The inside edges shall be filed so that there can be no possibility of

damages to cables from the edges.

To ensure the alignment of the ducts, a working mandrel of 457mm in

length and 83mm in diameter shall be drawn through as the ducts are

laid.

The test mandrel used for testing and cleaning shall be 457mm in

length and 83mm in diameter, the cylindrical brush shall be 108mm in

diameter.

8.3 P.V.C. DUCTS

P.V.C ducts shall be supplied in 6m lengths. The ducts shall be stored

away from the direct rays of the sun. A solvent cement shall be used

for the process of jointing. The ducts shall comply with STM

Specification Lines D 0011. The trench shall be scooped out at all

points where the spigot rest, so that the duct lies upon rammed sand.

The condition for duct laying as detailed in Section 8.1 shall be

applied. Where one line of ducts is laid over another in the same

trench, sand shall be filled in and over the lower lone of ducts and

carefully rammed to form a bedding of 50mm in thickness for the top

ducts. Sand shall also be rammed between the ducts laid side by side

in the same trench. The ducts shall break joint by approximately half

the duct length in alternative lines, horizontally and vertically.

If it is necessary to deflect from a straight line or to vary the

depth, sets shall be given to the joints but deflections shall not be

greater than 12mm per 610mm run of the single ducts. Short ducts not

less than 610mm in length, shall be built into the track in order to

ensure the required deviation.

Ducts shall be cut when necessary, at right angles to the bore only,

preferably with a saw in a simple cutting guide. The inside edges of


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____________________________________________________________________________________________the ducts shall be trimmed so that there shall be no possibility of

damages to cables from the edges.

The spigot of the ducts shall be wiped clean. The solvent cement shall

be applied to the spigot as well as the end of another duct. The end

of the ducts where the solvent cement ware applied shall be positioned

and pressure applied for the two ducts to be jointed. In no

circumstances shall dirt or grit be allowed to enter the joint.

To ensure the alignment of the ducts, a working mandrel of 457mm in

length and 83mm in diameter shall be drawn through as the ducts are

laid.

When the construction of the jointing chamber is deferred, the last

joint of each duct shall be tested on completion of the jointing

chamber by means of the working mandrel mentioned above.

The test mandrel used for testing shall be 457mm in length and 83mm in

diameter, the cylindrical brush shall be 108mm in diameter.

8.4 ENCASING IN CONCRETE

The method of encasing ducts in concrete in the layer by layer method

where each duct is completely surrounded by concrete.

To install P.V.C ducts around curves, the rigid ducts shall be bent to

avoid obstacles or to negotiate curves.

The ducts shall be cold bent around stakes for radii above 10.6m. To

provide favourable cable hauling conditions, the radii should be as

large as possible. Cold bending in situ to the curve required is

achieved by provision of stakes to form the ducts to the required

shape. The stakes must be spaced at intervals not greater in length

than 1/20th of the radius of curvature or alternatively as indicated in

the Table below.

Bend

Radius

11.6m

-

11.2m

12.2m-

15.2m

15.2m-

18.2m

18.2m-

21.3m

21.3m-

24.3m

24.3m

-

27.4m

27.4m

-

304m

Support

Spacing

53.3

cm

61.0

cm

76.2

cm

91.5

cm

106.7

cm

122.0

cm

137.2

cm

Concrete cover above the top duct of a complete tier is to be a

minimum of 51mm.

After the initial set of concrete has occurred and before it sets

hard, all stakes shall be withdrawn by applying a lifting and turning

action to the stakes. Where additional ducts are to be installed abovethe first nest, the stakes shall be withdrawn until approximately

305mm remain embedded.


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8.5 FIXING DUCTS TO BRIDGES

The following two methods shall be used for fixing ducts to bridges :-

(i) fixing to steel R.S.Js or fabricated beams.(ii) Fixing to reinforced concrete bridge beams and masonry walls.It should be noted that extra care shall be taken when it is necessary

to make holes for fixing bolts in existing bridge beams. All bridge

fittings shall be thoroughly cleaned and painted with one coat of

bituminous paint.

Where it is necessary for duct to pass through abutment walls, the

masonry or brickwork shall be arched over the pipe, the diameter of

the hole thus formed shall be at least 13mm more than the external

diameter of the duct. The space between with masonry or brickwork and

the pipe shall then be filled with bitumen to provide a cushion of

bitumen to the perimeter of the pipe at least 13mm thick.

8.6 DUMMY DUCTS

One length of P.V.C ducts shall be positioned, in a wall of the

chamber or above the row of ducts terminated at a jointing chamber.

When it is necessary to increase the number of ways, the new ducts

shall be jointed to the dummy ducts and the ducts shall be made

available by breaking the mortar seal that was set previously in

position when the ducts and chamber were constructed.


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9.0 JOINTING CHAMBERS

9.1 TYPE OF MANHOLES

The standard types and sizes of manholes with code reference are shown

in the following tables :-

Reinforced Concrete Construction

Throughout

Internal Dimensions

Code STM

Standard

Drg. No.

Figures Length

(cm)

Breadth

(cm)

Height

(cm)

RO

RIA

RIB

R2Bmod

fr

RI3

RI3

mod.

R2A

R2B

R2A-

E

R2A

Mod.

R4

R6

R7

SM.

No.1

SM.No.2

SM.

No.3

13359/1

SHTI&4

}13359/1

}SHT&4

}19488/0}

}

19658/0

}

}13359/1

}SHT3&4

19636/0

19632/0

19634/0

19614/1

19615/1

}

}

}10750/2

}

}

}

}

}}

}

Rectangular

152

152

152

152

305

132

305

305

305

366

410

140

144

305

305

106

122

122

122

122

122

122

122

152

182

305

213

122

244

244

152

168

198

198

182

182

192

182-244

182

182

182

305

182

213

213

TABLE 1 (Contd.)


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R3

R5

R9

R9 MOD.

R10

R10 MOD.

R11

R12

R13

R14

R15

R16

19633/0

19609/1

19578/2

19649/0

19579/2

19652/0

19580/0

19588/0

19594/0

19638/0

19637/0

19635/0

A

S

S

O

R

T

E

D

S

H

A

P

E

S

&

S

I

Z

E

See STM Drawing

19650/0 for size and

shape

Table 1 (Contd.)

Reinforced Concrete Internal Dimensions

Code STM Standard

Drg No.

Figure Length Breadth Height

RT88 19485/0

19482/0

SHT.1&2

19484/1

19486/0

D A D

B B

F

A B C

117cm 107cm 244cm

F

274cm 182cm


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9.2 TYPE OF JOINT BOXES

The standard types and sizes of joint boxes are shown in the following

table :-

TABLE 2

Item Code STM

Standard

Drawing

Number

Length Breadth Internal

Depth

Carriag

eway

Joint

Box

Carriag

ewayJoint

Box

Carriag

eway

Joint

Box

to

accommo

date

L.P.

200 pr

JC9

Mod.

JC9C

Mod.

19647/1

19646/1

19540/0

157cm

182cm

244cm

66cm

97cm

97cm

107cm

144cm

108cm +

61cms.H

Note: Normal depths are indicated and shall be measured from the carriageway

of footway surface to the top of the floor in each case. They may

however be varied to suit the depths of the ducts.

All jointing chambers whether built of brick or reinforced concrete

shall be of waterproof construction. Ducts shall enter manholes at

such a depth to ensure a clearance of at least 460mm between the top

of the barrel of the uppermost ducts and the underside of the roof of

the manhole. Except where a duct seal is provided, when a clearance of

203mm is required clearance of 152mm depending on type of manhole,

shall be given between the outside of the barrel of the ducts and the

adjacent wall, and a minimum clearance of 460mm between the undersideof the lowest duct duct and the floor.

Where the duct capacity of any proposed manhole is not fully utilized,

the space shall be fitted with dummy ducts for future duct growth by

laying initially at standard depth. The dummy ducts shall be sealed

with cement mortar inside the chamber wall. To ensure that cables can

easily be housed in manholes with a minimum bending, the ducts shall

be splayed over the last length to enter the manhole equally on either

side.


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9.3 MANHOLE CONSTRUCTION

The ground shall be excavated to the required dimension, the sides of

the excavation shall be supported by poling boards or by other means

if there is any likelihood of the earth falling in. The foundation

shall taken leveled and rammed. Soft ground shall be dug out, filled

in with hardcore and consolidated.

Two light wooden template, slotted (not drilled) to receive the

reinforced bare shall be set up. The lower template shall be fitted

about 305mm above the foundation and shall be supported on four small

pegs at its corners. The upper template shall be fixed to correspond

with the lower template, but about 305mm below the position of the

roof of the manhole.

In the process of erecting the floor of manhole, shuttering for the

sump hole shall be set up and concrete laid over the foundation to a

thickness of 38mm.

The ends of side-wall-to-floor corner reinforcement shall be placed so

that horizontal portions are just covered by the concrete. The

vertical portions shall pass through the slots in this template and be

set so as to obtained 19mm cover from the outside face of the walls

when these are erected. Additional concrete shall next be laid until

the level is 19mm less than the concrete level for the floor. This

shall be done as soon as possible after placing the first layer of

concrete, so that the two layers units thoroughly. Anchor irons shall

be set in the floor in accordance with the relevant STM Standard

Drawings. The interior wall reinforcement shall be placed with the

horizontal portions flush with the surface of the concrete in the

floor and the vertical portions passing through the slots of both

template as to obtain 19mm cover from the interior face of the walls

when these are erected. To remaining 19mm layer of concrete shall than

be laid to reach the specified floor level.

The erection of the walls shall be commenced when the floor has been

left for at least 12 hours. The portion of the floor on which the

walls will be erected shall be cleaned and rendered with a 7mm

thickness of neat cement., well trowelled and placed in position, just

before wall concreting is commend. The wall shall as far as possible

be erected continuously to their full height, but if during erection a

break of 2 hours or more is unavoidable, the existing work shall be

cleaned and rendered as previously described.

The horizontal bars and side-to-end-wall corner reinforcement shall be

placed as walls are built up. Steps, manholes, bolts and cable bearersshall than be set in the walls. The template shall be removed when

work reaches such a stages that they impede the placing of the

concrete.


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____________________________________________________________________________________________

When the walls have been built to the requisite height, shuttering for

the roof shall be set up and the boards being arranged to form a

recess at the position of the roof beams. A 26mm thickness of concrete

shall then be laid throughout the roof area, including the recess of

the beams. The beam reinforcement which have been previously assembled

by threading and wiring of stirrups to the bars may now be laid and

the main reinforcing bars shall be set to obtain 26mm cover. The

remainder of the roof reinforcement shall be laid and to give the

correct cover of 19mm and the rods shall be just visible above the

surface of the concrete. The alternate bent bars shall be conveniently

supported by a single wire fixing at the point where they enter the

beam reinforcement. The concrete in the roof shall than be made up to

the necessary thickness and finally the roof-to-wall corner

reinforcement shall be embedded.

The correct cover of 19mm to the roof shall be checked by a wood

spike. Correction at each end of the horizontal part of the rod shall

ensure that the vertical portion has the correct cover throughout its

length. The upper face of the beams shall be spade-finished and theroof given a slight slope to the sides to avoid accumulation of water

on the roof.

The shuttering shall be struck and the floor shall be rendered with a

19mm cement mortar, with a fall to the sump hole on all sides and the

manhole frame shall then be fitted.

The arrangement of reinforcement for each type of manhole are as shown

pictorially in the relevant STM Standard Drawings as listed in Table

1.

The minimum concrete curing time for jointing chamber after completion

of concreting shall be as shown in the following table :-

TABLE 3 : Manholes Built In The Carriageway/Foot Way

Type of

Cement

Used

Minimum Period from Completion of Concreting

(a) to removal (b) before commencing c)before

of shuttering commencing allowing

reinstatement passenger

of traffic

Portland

Cement orits

equivalent

Rapid-

Hardening

Cement

High

Alumina

Carriage-

way

5days

2days

10hrs

Foot-

way

5days

2days

10hrs

Carriage

-way

7days

3days

24hrs

Foot-

Way

5days

2days

24hrs

Carriage-

way

7days

3days

24hrs

Foot-

way

7days

3days

24hrs


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____________________________________________________________________________________________Cement

The striking of the shuttering shall be commenced before the

expiration of 12 hours and the concrete shall be prevented from

becoming dry at any time by watering it within 24 hours of mixing.

9.4 JOINTING CHAMBER FITTINGS

The following fittings in the jointing chamber shall be hot-dip

galvanized and the following requirements shall be followed :-

(a) Grating for sump holes shall be fitted to the sump holes of allmanholes.

(b) Anchor iron shall be fitted in accordance with the relevantdrawing.

(c) Steps shall be installed in the position shown in the relevantdrawings for the manholes. The steps shall also be used in

entrance shafts for all manholes.

(d) Steel ladders shall be used in all type of manholes. The laddersshall be fixed in accordance with the relevant drawings to suitthe different heights of the manholes.

(e) Bolts shall be fitted for the attachment of cable bearers. Inall types of manholes, the bolts required for the walls shall be

fixed temporarily in the shuttering during the construction of

the manhole to ensure that they shall remain in their correct

position while the concrete is setting. The positions for holes

in the shuttering shall be obtained by using the cable bearer as

a template.

(f) The cable bearers shall be fixed to the walls as described in(e).

(g) The brackets for cable bearers shall be in accordance withrelevant drawing and the initial provision shall be 2 per Cable

bearer, e.g. in a R2A type manholes, where the cable bearers are

fitted 3 to a wall making a total of 6 cable bearers, the number

of brackets provided shall be 12.

(h) The pins locking and cable bearer shall be designed tofacilitate the removal of brackets.

9.5 FITTING OF MANHOLE COVERS

Manholes Cover No.3E shall be fitted in all classes of manholes inaccordance with the relevant drawings. Manholes Covers No. 7E shall be

fitted in all classes of joint boxes in accordance with the relevant

drawing.

(a) Where the manhole is to be set at the minimum depth (as shown onthe standard manhole drawings), one course of brickwork shall be

laid between the manhole roof and frame.


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____________________________________________________________________________________________(b) Where, due to anticipated alternations in level, the manhole is

to be set at an increased depth, one or more additional course

of brickwork shall be laid. This is particularly important in

the case of manholes built in the footway where there is

possibility of the frames and covers being installed to

carriageway level at a later date. Cement mortar shall be used

both for setting the brickwork and for bedding the manholes

frame.

(c) 24 hours must elapse after the building of a jointing chamberbefore the frame and cover are installed. The water used in the

concrete shall not exceed 643 litres per cubic metres.

The frame shall be positioned accurately in relation to the cover

before being filled so that the cover is flush and level with the

surrounding carriageway. Two methods of filling and setting may be

employed :-

(i) In-situ filling The frame shall be embedded on a layer ofstiff cement mortar, care being taken to ensure that the frameis fully supported along all the four side.

The level of the frame shall be adjusted to the level of the

surrounding road surface by pieces of mild steel packing

approximately 152mm x 51mm and of appropriate thickness. The

cover shall than be placed in the frame. When the cover is

correct suited, the edges of the frame and the cover shall be at

the same level. If any irregularly can be felt by running the

finger along the joint, or if the cover rocks, the frame shall

be packed up until the edges are at the same level and the cover

is free from rocking. The cover and the frame shall then be

filled with concrete of Quality G, or an asphalt and granite

mixture. Great care shall be taken when filling the frame to

ensure that no voids are left, the concrete in each pocket shall

be thoroughly tamped with to reinforcing rod. Finishing shall be

done with a trower the concrete in the cover compartments being

left slightly proud but not more than 3.2mm at the edge to 6.4mm

crown in the center of the cover to allow for shrinkage, wear

and to protect the metal webs. The lettering on the plate

bearing the STM marking shall be left clear.

(ii) Where in-situ filling is not possible, the frame shall be placed

on a level surface with a piece of building paper beneath it to

prevent concrete adhering to the floor. The leveling of the

frame and cover, and the concrete filling shall then be done as

described in method (i). The frames and covers must be left

undisturbed for a minimum of 3 days. When the frame isinstalled, it shall be bedded on stiff 1:3 cement mortar.


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____________________________________________________________________________________________Shuttering shall be struck as follows :-

(i) For carriageway joint boxes, after the lapse of time given in

Table 3 of section 9.3 of this specification.

(ii) For footway joint boxes, after 24 hours, irrespective of the

type of cement used. A 20mm cement mortar rendering shall be

applied to level the floors or they shall be built up to give

25mm drainage fall where required.

Manhole cover No.7E shall be fitted to all joint boxes and the method

as described in Section 9.5 of this specification shall apply.

9.7 PROTECTION OF CABLES AND ASSOCIATED EQUIPMENT

The Contractor shall take such measures, to protect cables and

associated equipment during the cutting of duct entries into existing

structures or the demolition and rebuilding of jointing chambers. Such

measures may include any or all of the following :-

(a) A ladder must be provided by the Contractor for the access ofmanhole excavation. Under no circumstances shall cable, joints

and associated equipment be used for climbing, standing or

sitting on.

(b) Sufficient pumping capacity shall be made available to ensurethat when cables are removed from their bearers they shall not

be immersed in water at any time.

(c) All cables shall be protected at duct entries by packing withfoam rubber to act as cushion when any movement occurs.

(d) During demolition of the roof of a manhole the Contractor shallerect a deck of timber between the cables and the roof of the

manhole to protect the cables etc. from falling debris in the

following manner :-

(i) A minimum of three 229mm x 76mm timber upright shall be

evenly spaced against each long wall of the manhole with

the 229mm side against the wall. The length of the upright

shall be such that the terminate approximately midway

between the uppermost cables and the roof. Further length

of horizontally on top of the uprights and between the

uprights at the bottom, all positions shall be wedged and

blocked to the satisfaction of the S.O.s Representative.

Lengths of poling boards or other similar timber shallthen be placed on top of the horizontal supports.

(ii) When the manhole roof and walls have been demolished down

to the level of the timber decking and all debris and

decking removed, the cables and other associated equipment

shall be suspended from beams on the surface of the ground

to the satisfaction of the S.O.s Representative.


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____________________________________________________________________________________________(iii) Cables and joints and other equipment shall be protected

by wrapping (not tying) with several layers of sacking

while timber decking is being erected or dismantled.

(e) During rebuilding operations, cables shall be supported on

wooden benches with cushions of sacking or similar

material once the floor has been laid and the concrete

allowed to set.

9.8 BONDING AT JOINTING CHAMBERS FOR EARTHING FACILITIES

Where metal pipes are laid and terminated at jointing chambers, the

break in continuity shall be made good by embedding 51mm x 3.2mm G.I.

strips of required lengths in the walls of the jointing chambers

during construction. The ends of the G.I. strips shall be welded to

the pipes.

10.0 INTERIM RESTORATION, BACKFILLING AND PERMANENT REINSTATEMENT OF ROADSAND OTHERS

10.1 INTERIM RESTORATION

The Contractor shall execute interim restoration of all trenches and

ducts in accordance with the provisions and specification laid down by

JKR and other relevant authorities. A layer of sand shall first be

laid on the bed of the trench and hand punned to a thickness of not

less than 50mm before ducts are laid. All ducts shall be covered by a

layer of sand and hand punned to a thickness of not less than 50mm.

10.2 BACKFILLING

The spaces outside the walls of jointing chambers and surrounding area

shall be completely filled with sand free from stones in 230mm layers

and rammed. Care shall be taken such that the ramming shall not

disturb any recently completed work.

All materials shall be replaced in 150mm layers in the reverse order

to which they were excavated. The remaining 300mm top of the trench

shall be backfilled with good quality red earth and the materials

previously excavated shall be placed on top and the gaps filled with

quarry dust. All backfilling shall be thoroughly compacted at each

layer using a mechanical rammer. If mechanical rammer is impracticable

and hand ramming is employed, there shall be at least three persons

ramming to one filling. Where S.O.s Representative required

backfilling of trenches completely with sand or quarry duct, allexcavated materials shall be removed from site, and backfilling shall

be carried out as described in the following paragraph.


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____________________________________________________________________________________________For all road crossing in carriageway, after the bedding of a layer of

sand in the trench has been satisfactorily carried out, the

backfilling shall be done with nothing else except sand or quarry duct

in layers. Each layer shall not be more than 230mm in thickness and

well rammed with mechanical rammer or watered down before the next

layer is laid. The top 300mm shall be backfilled with quarry dust

only. This shall be done in tow layers, one layer to be rammed with

mechanical rammers before the next layer is laid. The top layer shall

be rammed with mechanical rammer until it is flushed with the road

surface.

Backfilled excavation shall be tested by applying a power frog rammer

repeatedly over on half a square meter area for a period 3 minutes and

shall performed by the Contractor as instructed by the S.O.s

Representative at intervals he considers necessary.

The compactness shall be considered satisfactory of the test shows no

measurable change in level, a measurable change in level being a

depression which cannot be rectified by reshaping the tested area and

consequently requires additional imported material to restore thesurface of the test to the original level. Should any measurable

change in level occurred, then the area of faulty compaction, defined

by the results of this and further tests, shall be rectified by the

Contractor.

The reinstatement portions of unpaved footways or other excavations

shall be maintained by the Contractor and he shall ensure that they

shall be leveled and turfing shall be replaced to the satisfaction of

the S.O.s Representative. Any subsidence of other defects arising

during the Defects Liability Period shall be made good by the

Contractor.

10.3 PERMANENT REINSTATEMENT OF ROADS

Permanent reinstatement shall commence only after the back filling and

interim restoration has been allowed to settle well and that there is

no measurable change in level.

The reinstatement shall be carried out by removing the back filled

material from the trench to a depth of 300mm which shall then be

filled with a 250mm crusher-run stone (limestone or granite) not

exceeding 62mm in size and the voids between the metal filled with

quarry dust to serve as a bind. Where possible, consolidation by

rolling shall be carried out with an 8 tonne roller utilizing a

special hydraulic rolling wheel attachment. Elsewhere consolidation

shall be effected by means of power driven rammer. The 300mm crusher-run stone base for trenches within carriageway shall be consolidated

in 2 layers of 150mm each. The foundation of the footway shall be

consist of a layer of not less than 125mm of quarry dust. The layer of

quarry dust shall be rolled with a 2 tonne roller or by means of a

power driven rammer.


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____________________________________________________________________________________________A tack coat cationic bituminous emulsion (40%) must be applied to the

rolled crusher-run stone base/quarry dust base at the rate of 4.5

square metre per litre before the premixed asphalt macadam surface is

laid.

When the consolidation of the stone foundation is completed, premixed

asphalt shall be spread evenly over the treated stone surface/quarry

dust surface and rolled until complete consolidation has been obtained

and the resultant surface left slightly proud of the existing adjacent

surface. For carriageway consolidation, an 8 tonne roller shall be

used and for footpath consolidation, a roller not exceeding 2 tonne

shall be used. All surplus material shall be removed from site by the

Contractor on the same day the trench has been backfilled. The

Contractor shall be responsible for maintaining the backfilled trench

until the surface reinstatement is complete.

11.0 WORKING DRAWINGS

Within three weeks after award of the tender or such shorter period as

may be required by the S.O.s Representative, the Contractor shallsubmit to the S.O.s Representative for his approval, four sets of

detailed drawings the positions of manholes/joint boxes and cable

ducts routes. The drawings submitted shall be modified if necessary as

required by the S.O.s Representative and submitted for final

approval. It is to be understood, however, that approval of the

drawings will not exonerate the Contractor from any responsibility in

connection with the works.

12.0 SERVICE AND MAINTENANCE

During the Defects Liability Period, the Contractor shall perform

service and maintenance work for the complete installation by skilled

persons. All works, materials, tools and parts necessary to rectify

the defects due to manufacturing/installation/construction faults

shall be supplied/executed by the Contractor at no extra cost to the

Government.

The works to be performed shall include but not be limited to the

following :-

(a) Replacing and making good all manholes, joint boxes, ducts etc.(b) Making good any damage to roads, buildings, drains, cables,

pipes, concrete areas, paved areas etc. which had not been

properly made good.

(c) All other works as deemed necessary by the S.O.sRepresentative.

The maintenance work shall be carried out as soon as the

Contractor has been informed by the S.O.s Representative. If

the work has not been carried out and completed within a

reasonable period, the S.O.s Representative reserve the right

to engage another party to carry out the work in which case, the

Contractor shall be responsible for all the expenses incurred.


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____________________________________________________________________________________________13.0 AS INSTALLED DRAWINGS

Within three calendar months after the practical completion of the

project, one set of true to scale negative (110/115gm sq.m) and four

sets of prints of the layout of cable duct routes, manholes and joint

boxes with reference to easily recognizable buildings and structures

shall be submitted.

These drawings shall be provided whether or not they are separately

itemzed in the Bills of Quantities of the Tender Document. The cost of

all these drawings is deemed to be included in the Tender Price.

These drawings shall be properly stenciled and shall have at the lower

right hand corner the Contractors name and address date of

commissioning, scale, drawings number.

If the drawings submitted are not acceptable by the S.O.s

Representative, the Contractor shall amend and resubmit the drawing

within two weeks from the date of return of the drawings.

specification for construction of manholes,

Documents