general method statements

Rehabilitation and Upgrading of Pakpattan Canal,Khadir Branch and Pakpattan Islam Link

Contract: PCSBIP/ICB-01

1. SETTING OUT THE WORK

1.1 Objectives:

The purpose of this method statement is to define the procedure for true and proper setting out of

the works in relation to the points, lines and grades of reference given in specification and

drawings.

1.2 Scope:

For the construction of different types of structures, canal banks or excavation, the setting out

work includes proper demarcation and laying out at site, the structure’s dimension in accordance

with specification and drawings or Engineer’s instructions.

1.3 Procedure:

Prior to the commencement of actual execution, the centerline of the canal, Hydraulic structures

or excavation will be clearly marked on ground with the help of total station. Temporary Bench

Marks will be installed close to the proposed structures or on the canal banks where the earth

work has to be done. The exact position of the structures to be constructed will be identified by

means of demarcation / layout plan. A deep furrow shall be excavated and pegs shall be installed

at every 50 ft along the alignment. Top and bottom edges of the excavation and toes of the

embankments shall be clearly staked out. All curves along the alignment shall also be properly

laid out. After making the alignment, a complete profile of the embankment or excavation shall

be set out at 100 ft intervals or every change of section and at every curve. The profile shall

have a dimension of 10 ft and shall be constructed to the proper shape and lines and grades. All

necessary arrangements shall be provided in this profile.

1.4 Tools & Equipment

Total Station

Pegs with red flags

Measuring Tape

Spikes

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Templates

Platforms etc.

1.5 HSE Instructions

Material and equipment will be maintained in an orderly manner.

All efforts will be made to keep the environment neat and clean.

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2. CARE AND HANDLING OF WATER

2.1 Purpose

The purpose of this method statement is to define the procedure to enclose the area for the re-

construction / rehabilitating the hydraulic structures without interrupting the flow in existing

irrigation canals.

2.2 Scope

The work to be done under care and handling of water shall consist of, but not limited to:

Construction of diversion channels in accordance with the diversion channel plans

approved by the Engineer.

Protection of all works and structures to be constructed from rains and surface runoff

during the entire period of construction so as not to be interrupted the construction of

works.

Dewatering and maintain all foundations, excavation and surfaces dry and free of water

required for proper construction of the works.

Not to disturb the flow in existing irrigation canal, distributary channels, water courses

and natural drainage system of the area.

Furnish water for all aspect of construction.

2.3 Procedure

For the reconstruction of hydraulic structures, the diversion channels are required to be

constructed so as not to disturb flow in the existing irrigation channel during the period, the

structures remained under construction. The diversion channels will be constructed as per

approved plan by the Engineer. The diversion channels have the following components:

i. Main Diversion channels

ii. Mouths U/S & D/S

iii. Plug Bunds U/S & D/S

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As the plans of the diversion channels have already been approved by the Engineer and the

works of excavation of the diversion channel will be started as soon as possible on getting the

sites cleared from the trees standing in the alignment of diversion channels. However, the work

of construction of mouths U/S & D/S and plug bunds U/S & D/S will be carried out during

annual canal closure exactly in accordance with the approved drawings.

Dewatering pumps will be installed, maintain and operated for dewatering the rain and surface

runoff for keeping the foundation dry and free from water as required for the construction of the

structures. Prior to beginning of any dewatering for works, a dewatering plan will be proposed

and got approved from the Engineer. The dewatering plan shall be proposed in a manner that will

maintain stability of excavated slopes. Any seepage along the bottom of the foundation and

elsewhere will be controlled to prevent the accumulation of standing water. Trenches of adequate

depth will be excavated at U/S & D/S of the proposed structures. Dewatering pumps with motor

or peter engines will be placed at extreme ends of trenches to dewater the collected seepage. In

addition to these, four dewatering pumps two each at U/S & D/S of structures will be installed to

further lower the water of sub-surface.

2.4 Tools & Equipment

Electric Motor pumps




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3. SURVEYING3.1 Objective

The purpose of this method statement is to define the procedure for carrying out survey work.

3.2 Scope

This work instruction covers the survey work under the project specification, codes and

standards.

3.3 Responsibilities

Site Manager will be responsible for implementation of this work instruction.

QA/QC Manager will ensure that all the relevant work is carried out in conformance with project

specification.

3.4 Procedure

Steps to be taken for performing this activity are as under:

Temporary bench marks will be established with the help of bench marks specified in the

approved drawings or fixed by the Engineer. These bench marks will be maintained for the

proper execution of the works in the vicinity thereof, in perfect condition and to the

satisfaction of the Engineer.

The additional bench marks will be established in a way that no level would be transferred

more than 3000 ft.

The bench marks will be numbered.

Maps and records in an approved form in duplicate giving details of the location (including

coordinates) and level of each bench marks shall be provided to the Engineer.

Field books and tabulated data will be maintained.

Survey data shall be recorded in accordance with the recognized professional surveying

standard, original field notes, computations and other survey data shall be recorded in the

field books.

3.5 Tools and Equipment

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Total station with all accessories

Auto level with all accessories

Measuring tape

Spray paint for marking

Calculator / Computer

3.6 HSE instructions



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4. EXCAVATION (MAIN CANAL / STRUCTURES)

4.1 Objectives

The objective of this general method statement is to define the procedure for carrying out

excavation in Main Canal / Structures.

4.2 Scope

This work instruction covers the excavation of Main Canal / Structures under the project

specifications, codes and standards.




specification.

4.4 Procedure

Steps for performing this activity are as under:

All excavation for Main and Branches shall be done accordingly to the designed section

shown on the drawings or instructed by the Engineer.

The excavation of the Main Canal and Branches will be executed through mechanical

means.

Full details of the earth moving machinery shall be provided in accordance with the

bidding document.

A plan for earth works operation, detailing the locations and program of excavation will

be prepared and submitted to the Engineer for approval.

The survey of the area to be excavated shall be carried out and marking the excavation

layout and slope cut stakes as per excavation plan.

Determination of ground level and depth of excavation required.

Check request for joint verification of NSL and layout of the area will be submitted to the

Consultants.

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For deep / loose excavations proper shoring with sheets will be provided.

Suitable material excavated from the channel shall be placed alongside of fill to from

berm and inspection paths as per drawings.

Excavated material containing stumps, roots, vegetation matter and other unsuitable

matters should be placed in the designated spoil banks or as directed by the Engineer.

Frequently checking the levels of excavations as per drawings to avoid extra cutting

during the progress of work.

The inspection paths will be formed with material excavated from bed and from borrow

areas.

All spoil banks shall be leveled and sloped to channel and trimmed to reasonably regular

line or as directed by the Engineer.

Compaction at the bottom of excavation will be done and checked / tested as per

requirements of the project.

All necessary precautions will be taken to preserve the materials below and beyond the

lines of all excavations in the soundest possible conditions.

Any excavation made for our convenience, for any purpose or reason shall be back filled

properly and compacted to the required specifications.

Check request will be submitted to the consultant for final approval.

4.5 Excavation in Foundation of Structure

The bottom and side slopes of excavations upon or against which structures or other

required construction are to be placed shall be finished accurately to the required grades

and dimensions and if required by the Engineer, shall be moistened with water and rolled

with suitable tools or equipment for the purpose of forming a firm foundation.

The disturbed or loosened foundation material or excavated beyond the approved lines

and grades, shall be removed and the over excavation shall be back filled with selected

material and will be thoroughly compacted by rolling in layers not exceeding 6 inches

according to the required specifications.

Unsuitable material for foundation shall be removed and backfilled with selected

materials thoroughly compacted in layers.

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All excavation shall be kept free from water, from whatever source it may come from, at

all times to the satisfaction of the Engineer.


Survey equipments.

Excavators.

Shovels.

Dozers with ripper.

Front end loader.

Dump trucks or Tractor Trolleys.


Material and equipment will be maintained in an orderly manner. Prior to excavation, a survey will be carried out to find underground utilities (like

overhead lines etc.) All shoring shall be constructed capable of withstanding collapse. All efforts shall be made to keep Environment clean.

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5. BACK FILLING AROUND STRUCTURES

5.1 Objectives

The objective of this work is to define the procedure for carrying out back filling around

structures.

5.2 Scope

This work instruction covers back filling around structures under project specifications, codes

and standards.




specification.

5.4 Procedure

All fill or backfill around structures below the NSL shall be placed as compacted fill.

All fill or refill around structures above the NSl shall be placed as compacted

embankment except as otherwise specifically mentioned in the drawings.

Where sufficient materials are not available from the required excavation to construct the

embankment or backfill, suitable materials shall be excavated from borrow pits located in

designated areas.

The unsuitable material not required for backfill shall be placed in designated spoil

adjacent to the canal or road.

All material designated for use in compacted embankments shall have the proper water

content either in natural state or to be achieved by sprinkling water or other suitable

means before and during the backfilling.

Approved backfill material will be spread in layers horizontally.

Layer of backfill material will be of uniform thickness with a slight outward slope.

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Compaction of backfill material layers will be done by mechanical rollers, rammers or

any other approved plant.

Compacted depth of backfill material will not be greater than 6”. In placing and

compacting backfill or embankment adjoining structure, sufficient material shall be

carefully placed initially on sides.

The material in backfill shall be compacted until the dry density of the compacted

material in not less than 90% of laboratory max dry density.

All possible help will be provided to the Engineer for taking representative samples to

carry out the compaction tests.


Mechanical rollers

Rammers

Excavators

Dozers

Dumpers / Tractor Trolleys



Back-mirror will be used if backfilling is done by reversing dumpers etc.

All efforts will be made to keep Environment clean.

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6. PROCURING CONCRETE AGGREGATES

6.1 Objectives

The objective of this work is to define the procedure for the procurement of concrete aggregates.

6.2 Scope

This work instruction covers the procurement of concrete aggregates under the project

specification, codes and standards.




specification.

6.4 Procedure

Steps for performing this work activity are as under:

All the aggregates required for the construction shall be handled, loaded, transported,

unloaded and stockpiled after the approval of the Engineer.

The location and arrangement of all stockpile area shall be subjected to the approval of

Engineer.

All sites / area designated for stockpiling of aggregate will be cleared and evenly graded

for drainage.

Stockpiling operation for the aggregates shall be handled carefully so that the segregation

and the breakage of aggregate may be kept minimum.

The stockpiled materials will be protected and will not be contaminated with soil or other

foreign material due to rain, surface runoff or sub-surface water.

The contaminated or segregated material due to improper stockpiling will be reprocessed.

The stockpiling operation will be conducted in such a manner as to deposit all material

directly in final position in the stockpiles and in layers not more than 4 feet deep.

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The aggregates shall not move from place to place in the stockpiles excepts as superficial

leveling may be necessary to provide suitable roadway for trucks in placing successive

layers.

Effective means will be provided to prevent breakage of aggregates caused by trucks

operation over the stockpiles.

Dumping over the ends or sides of the stockpiles will be avoided.

To avoid breakage, necessary measures by running down the out side slopes of stockpiles

shall be adopted.

The total capacity of the storage for each category of aggregates shall be sufficient to

ensure progress of work on the site for a duration of at least 5 days.

6.5 Tools and Equipment:

Loading trucks Independent laboratory having facilities of performing standard tests of aggregates.

6.6 HSE Instructions:

Material and equipment will be maintained in an orderly manner. All efforts shall be made to keep Environment clean.

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7. PROPORTION OF CONCRETE MIX

7.1 Objective

The objective of this work is to define the procedure for proportioning of concrete mix.

7.2 Scope

This work instruction covers the proportioning of concrete under the project specifications, codes

and standards.


Site Manager will ensure that the concrete design mix activities are conducted according to this

work instruction, latest project drawings & specifications.

QA&QC Manager will assure that all the relevant work is carried out in conformance

with project specification.

7.4 Specifications Required

Maximum W/C (water to cement ratio)

Minimum cement content

Air content

Slump

Maximum size of aggregate − Strength

Other requirements (strength over design, admixtures, special type of

cement, other cementations materials or aggregates)

7.5 Tests/Details Required

Sieve analysis of fine and coarse aggregates

Unit weight of coarse aggregates

Bulk specific gravity of fine and coarse aggregates

Absorption of fine and coarse aggregates

Mixing water requirements of concrete developed from experience with available

aggregates

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Relationships between strength and W/C or W/C (+ other cementations materials)

for available combinations of cements, other compendious materials if considered and

aggregates

Specific gravity of Portland cement and other cementations materials, if used

Optimum combination of CA (coarse aggregates) to meet the maximum density grading

for mass concrete

Oven dried robbed weight of CA − fineness modulus of FA (fine aggregates).

Moisture content of natural FA & CA

7.6 Procedure

i. Choice of slump:

ii. Related standard Project specifications.

iii. Choice of maximum size of aggregate

iv. Estimation of mixing water and air content:

v. Related standard Project specifications

vi. Selection of water-cement or water-cementation materials ratio:

vii. For Type I Portland cement and typical materials calculation of cement content:

viii. Use steps iii & iv If, however, the specifications specify minimum

cement content, the mixture must be based on whichever criterion

leads to the larger amount of content

ix. Estimation of CA content:

x. For less workable concrete, increase the CA content determined by up to 10% and for

more workable concrete (e.g. for pumping concrete), decrease by 10%

xi. Estimation of FA content:

7.6.1 The Weight method

Mass of FA = Mass of concrete (From experience) - (Sum of masses of water, cement, C.A)

OR

= 10 Ga (100 - A) - C (1-Ga / Gc) - W (Ga - 1)

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Where,

U = Unit wt. of fresh concrete (kg/m3), obtained from previous experience with the material

Ga = Weighted average specific gravity of combined fine and coarse aggregates, bulk,

SD GC = Specific gravity of cement (generally 3.15)

A = Air content

W = Mixing water requirement (kg/m3)

C = Cement requirement (kg/m3)

7.6.2 Absolute Volume Method

Volume of FA = 1- (sum of volumes of water, air, cementations materials, CA), where Volume of

each ingredient occupied in concrete = weight / density Weight / (Unit wt. of water x bulk sp. Gr.

Of ingredient)

Adjustment for aggregate moisture

A = Calculate moisture content of C.A & F.A

B = Calculate % absorption of C.A & F.A

C = Surface water contributed by C.A & F.A

C = A-B

D = Mixing water (net) = Mixing water calculated in step 3 – C

Trial Batch adjustments.

If slump not correct, increase or decrease the water content by 2kg/m3 of concrete for each

increase or decrease of 10mm in slump desired.

The estimated mixing water to produce the same slump, as the trail batch will be equal to

the next amount of mixing water used divided by the yield of the trial batch in m3

Re-adjust the cement C.A & F.A

General Mix Design Requirement

ACI standard 211.1.70 further leads us to compute the mass of sand in the mix. Manufactured sand

a product of riverbed having rough and angular surfaces, when couple with flat and elongated

shapes, it proudest harsh and not so workable concrete. A greater content of cement paste and

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grater water content then are necessary. We can calculate the approximately 28 days strength of

the mix by the formula, provided 7 days compressive strength is known: -

Sc28 = Sc +30 ScWhere

Sc28 = 28 days strength

Sc = 07 days strength


Concrete mixer

Slump cone

Roller meter

Laboratory equipments


Material or equipment will be maintained in an orderly manner and labeled in

accordingly with statutory requirements and use in safe manner.

Cement paste is also a skin irritant, rinse hand after handling cement paste, safety gloves,

safety boots and helmet will be used.

Any liquid fuel spills and accidental waste disposal will be avoided and properly cleaned

up.

All efforts shall be made to keep the environment clean.

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general method statements

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