DAEWOO-MS-DR-A1-EN

METHOD STATEMENT

Urban infrastructure Construction for THT Newtown Project Method Statement

For Technical Trench DAEWOOP1-MS-TT-A1-EN

CONTENTS1. General

---------- 22. Scope of Work

---------- 23. Construction Schedule ---------- 2

4. Site Organization Chart

---------- 25. Material

---------- 36. Equipment and Tools

---------- 37. Construction Procedure

---------- 48. Quality Control

---------- 129. Safety Control

---------- 1410. Environmental Control

---------- 14APPENDIXAppendix - Technical Trench - Construction shop drawing (File Attached)1. GeneralThis Method Statement is to describe the work procedures for the construction of Technical Trench. This work item shall be done in accordance with the contract and Chapter 16 of the Specifications. 2. Scope of work This method statement shall apply to Technical Trench work activities in construction of Urban infrastructure Construction for THT Newtown Project are as follows:Technical TrenchNoFunctionDimensionLength (m)Remark

BxH (m)Phase I (m)

1Technical Trench Type 10.8 x 1.41422

2Technical Trench Type 20.8 x 1.65143

The above quantities are only for reference. The design quantity will be made from approved shop drawings. The actual construction quantity will be shown on As-built Drawing.

3. Construction ScheduleConstruction Schedule shall be referred to Latest Overall Schedule. In addition, Technical Trench work shall be indicated and updated in monthly and weekly schedule. For each location, Detail Schedule shall be submitted together with working drawing.4. Site Organization ChartSite Organization Chart shall be referred to final approved The Site Organization Chart and Emergency Communication Flowchart.5. MaterialList of required material for construction is shown below:

When stored at site, materials such as rebar and Angle must be kept off the ground and shall be covered by vinyl sheet. Other materials used for backfilling shall be timely transported to the site.Nominal diameter and permissible deviation are specified in table below:

No.Internal diameterSpecified thickness

BxH (mm)Permissible deviation (mm)Specified thickness (mm)Permissible deviation (mm)

1800x140010150+5

2800x165010150+5

6. Equipment and ToolsList of required equipment and tools for construction is shown below:

7. Construction ProcedureWork Sequence for Technical Trench SHAPE \* MERGEFORMAT

All Material shall be divided into several segments (as indicated on approved shop drawing) and each segment shall be constructed one by one. The description of each segment work item is shown as follows:7.1 Preparatory Works

Construction of Technical Trench shall be commenced after shop drawing, method statement and working drawing have been approved from the Engineer.

Confirmation of approval for working drawings and preparation of working area shall be carried out before execution of work. Survey line marking and layout for Technical Trench shall be established. Mobilize all necessary materials and equipment before execution of work.Survey works has been carried out follow the benchmark, that was approved by Engineer. 7.2 Excavation, Trimming Works, Lean Concrete a) Excavation and trimming works shall be carried out based on approved Working Drawing. After excavation must be inspected by the Engineer, and the Excavation shall be cleaned and ensure safety and protect the slope.

Before carring out excavation work, Contractor must make sure cleaning for site. Excavation work: Construction and acceptance follow TCVN 4447-2012: Earth works Construction, check and acceptance.b)Survey marking shall be established prior for placing and casting lean concrete for foundation of Technical Trench and Manhole. Lean concrete shall be placed and casted as indicated in the Approved Shop Drawings. Mix Trucks tank must be rotated during transportation and concrete slump and temprature shall be checked at site prior to concreting. Placing concrete shall be carried out either by direct pouring, using excavator or crane and concrete bucket.7.3 Installation of Reinforcement Bara) Survey marking layout shall be carried out prior to rebar and formwork installation for concrete base.b) Rebar used for structures shall be in accordance with Specification of the Project and approved by the Engineer. Rebar manufacturing and testing follow TCVN 1651-2:2008 Steel for the reinforcement of concrete Part 2: Ribbed bars.c) Rebar, before and after fabrication, shall not be placed directly to the ground but firmly chocked and covered by nylon canvas to minimize all the external effects.d) Rebar shall be fabricated by cutting and bending machine at fabrication yard and shall be transported to construction site.

e) Rebars shall be installed and fixed with wires in workmanship manner based on Approved Shop Drawings. Rebar protection thickness shall be ensured by installation of pre-cast concrete spacer and follow Specification and Shop drawing.f) Starting rebars for next segment shall be installed and carefully protected from corrosion.g) After installation, rebar must be inspected by the Engineer. 7.4 Installation of Formwork7.4.1) Formwork shall include all temporary mould for forming the concrete. Falsework shall include all temporary constructions required such moulds, the weight of the concrete and all other applied loads.

7.4.2) Falsework shall be capable of with standing temperature changes without causing damage to the concrete.7.4.3) Falsework and centering shall be designed and construced to provide the necessary rigidity to support all loads placed upon it without undue settlement or deformation. 7.4.4) Falsework columns shall be supported on bases not on any part of the structure, except the permanent foundations.7.4.5) The forms shall conform to the shape and dimension of the structures shown in the issued for construction drawings and will be tight at joints in order to prevent leakage of cement paste.7.4.6) Form support and bracings shall be installed and properly fixed. Formwork and supporting system shall be ensured so that formwork is even without distortion and deformation during concreting.

7.4.7) Installed formwork shall even and tighten to avoid water leakage during concreting which may influence the quality and appearance of the structure. So that the gaps on form joint shall be treated and filled by cleat.7.4.8) Prior to concrete, entire surface of formwork shall be oily coated for easy dismantling in the next stage.7.4.9) Scaffolding, temporary staging and access ladders will be provided whenever necessary in order to access and egress work areas. And its shall be installed prior to install rebar and formwork.7.4.10) After installation, form alignment shall be carefully checked by survey works.7.4.11) Openings for the inspection and cleaning of the inside of formwork shall be formedand constructed so that they can be conveniently closed and properly sealed before placing of concrete.7.4.12) The work of striking (dismantling) the formwork will only be carried out undern the personal supervision of a competent foreman.

7.4.13) Formworks shall be removed after the concrete has achieved 80% of the designed concrete strength.

7.4.14) After removal of the formwork, all fins and projecting edges shall be cleaned from the concrete faces, which are to be exposed in the permanent works.7.4.15) Construction joint shall be chipped by steel brush and water to ensure loose concrete shall be removed until sound aggregate is exposed. 7.4.16) Curing procedures shall be initiated immediately after removal of formwork and completion of finishing work.7.5 Casting Concrete.

7.5.1) Prior to casting concrete, the below items shall be strictly followed:- Concrete casting by handle by manpowers. Plastic hose shall be provided and attached on the tip of mobile pump pipe to avoid the concrete segregation during casting.- Cleaning inside the form and water shall be sprayed on construction joint.

- Resources of materials shall be checked such as supply of concrete and equipments.

- Concrete casting equipment shall be set-up and check its condition before casting concrete. -Placing of concrete shall not be commenced until the engineer has inspected and passed the formwork or other area to receive concrete and any reinforcement, cast in fixings etc., against which the concrete is to be placed.-When all elements and procedures meet the requirements, concrete is then ordered.-Concrete shall be mixed at plant and shall be transported to site by concrete mixer trucks. Mixer Trucks tank must be rotated during transportation so that concrete shall not be segregated.

-When concrete arrives at site, immediately a quality control inspection such as grade, slump, temperature, time of batch, and time of arrival at site will be done, before placing is done to ensure that it is as per the specifications.- Pouring guide level shall be established for finishing. Pouring guide level shall be placed at the centerline transversely and a maximum distance of 2 meter longitudinally.7.5.2) During casting, the below items shall be strictly followed- Vibrators shall be used in workmanship manner in order to consolidate and compact the concrete properly. Vibrator shall be applied to area of concreting on a vertical position at 5 to10 sec at one place.

-The vibrator will be inserted systematically in a regular grid with spacing of insertion points depending on mix characteristics equipment. The grid spacing will be selected to ensure adequate compaction of all parts ofthe concrete, without over-compacting it. The spacing of insertion ofr normal area is n x d ( n=10, d=diameter of vibrator head)

- The poker vibrator would not be inserted closer to the form side than 3 times its diameter, and it must not be inserted in the cover layer (between the reinforcement and the form) The vibrator will be immersed vertically in its full length and through the entire thickness of the concrete layer. A sloped immersion will be madeonly if the thickness of concrete is less than the length of the vibrator.

- Regularly check the verticality of forms and necessary adjustment shall be made immediately if displacement or movement on forms is found.

- Discharging concrete shall be done layer by layer with a maximum I = (0.6 ~ 0.8) x S.

-The layer thickness would not be less than 0.5 x S to protect the vibrator.

Prior to casting of the next lift, the previously cast concrete top surface must be covered with a pure cement mortar layer. - Concrete supply shall be closely monitored to avoid cold joint.

- Tightness of the formworks shall be inspected regularly by the pouring guards to make sure that there is no deformation or displacement of forms and rebar and leaks at the formworks. During concreting, formworks and supporting system shall be always supervised to prevent problems if any. If displacements occur, immediate adjustment shall be done to reposition the forms or rebar before concrete placing continues.

7.5.3) Finishing. -Finishing on concrete surfaces will be done as per specified on the drawings.

-Appropriate tools and equipment such as straight edge brush, timber float, steeltrowel will be used at site to achieve proper finish.

After the water sheen has disappeared, the surface will be floated with a finishing machine using vinyl sheet. Trowel is to be done twice as minimum to avoid early shrinkage on the top of concrete. The water spray should be used during finishing operations and curing shall be started as soon as the surface of the fresh concrete is sufficiently hard to permit it without damage.7.6 Concrete Curing and Treatment of Construction Joint

7.6.1) Curing shall be done after concrete surface start dry. Concrete surface shall be covered by wet burlap or vinyl sheets. These burlaps or vinyl sheets shall be kept moisture during curing period. Curing shall be at least 7 days from finishing concrete.

.

7.6.2) Formwork removal can only be done at least 1 day after completion of concrete casting for vertical structure. After remove forms, concrete shall be covered by vinyl sheet for curing. 7.6.3) Construction joint shall be chipped by steel brush and water to ensure loose concrete shall be removed until sound aggregate is exposed.

7.7 Backfilling and Compaction 7.7.1 Backfilling and compaction shall be carry out layer by layer with material approved by the Engineer. 7.7.2) Each layer of backfilling shall be compacted until density of not less than requirements of that determined by TCVN 9436:2012 Highway embankments and cuttings Construction and quality control.7.7.3) Material placing and compacting

- The embanking/backfilling materials shall be black sand. The material shall be in accordance with TCVN 9436-2012.

Before making use of material the Contractor shall submit test results as required by the Engineer approval, showing exact locations and hauling distances of embanking/backfilling.- Embankment materials shall be placed continuously and horizontally with a thickness not exceeding thirty (30) cm before compaction. Compaction shall be done for each stratum in line with the conditions stated herein or as instructed by the Engineer.- Reference standards:

No.SpecificationsDescription

1TCVN 9436 : 2012Emankment work. Construction procedures and inspection.

222TCN 346-06Field density test sand cone replacement method

322TCN 333-06Max density of materials in laboratory

422TCN 332-06Determinate CBR index in laboratory

7.8) Cleaning Up SiteAll excess materials and rubbish shall be removed and disposed leaving the site neat, tidy and acceptable to the Engineer. 7.9) In Case of Emergency7.9.1) If it is necessary to stop placing concrete before a casting is completed, make the surface flat until the last available batch of concrete, and make proper construction joint. In case of rainfall, pooling water shall be removed from concrete surface before making the surface flat.

7.9.2) Extra specimens for concrete compression test shall be taken from emergency stopped concreting area in order to confirm the strength of concrete at the corresponding section.

7.9.3) In case of rainfall, all areas of concreting shall be covered by plastic vinyl sheet.7.9.4) If casting equipment breakdown, a standby casting equipment shall be utilized for concrete casting. Casting concrete shall follow the direction initially poured.8. Quality ControlThe whole procedure shall be thoroughly checked by the Engineer in charge for operation. Quality control shall be carried out in accordance with this Method Statement and other applicable specifications. Inspection and Test Plan and Inspection Checklist are attached as Appendix 2. Inspection and Test Plan and Inspection Checklist are subject to revision in accordance with the instruction by the Engineer.8.1) Tolerance for Concrete Structures The temperature and slump of concrete shall control quality as below table:

ItemsTemperatureSlump

Lean concrete 32C52.5 cm

Concrete Grade C1 32C102.5cm

8.2) Tolerance for Concrete Structures

Tolerance for concrete structure is shown as below table:

8.3) Testing frequency of materials for concrete shall be complied with chapter 10 of Specifications.8.4) Necessary tools shall be used such as level bar for controlling the elevation of concrete top surface during casting concrete. 8.5) Sampling of concrete for compressive strength test shall be in accordance with Inspection and Test Plan. 8.6) Slump test and temperature check shall be done on each concrete mixer truck delivered to site. The slump tests shall be carried out in accordance with TCVN 4453:1995 Monlithic concrete and reinforced concrete structures Codes for construction. Check and acceptance.9. Safety Control Safety control shall conform to Approved -HSE PROGRAM and that method shall be part of this Method Statement. Prior to start the construction work, the following particular matters are to be through to all members working in the construction site in order to complete the Drainage System and construction efficiently without any accident or casualty.

The Contractor proposed an adequate measures to ensure safety, security and environment during construction process in accordance with Decision 55/2009/QD-UBND date 17/03/2009 on Establishing Regulation for Security, Safety and Eviromental Sanitation during Construction works in Ha Noi City.9.1) Joint MeetingPrior to start any activity, a joint meeting with relevant staffs shall be held for the purpose of general explanation on the whole contents of works as well as the method for the implementation of efficient work in accordance with this Method Statement.

9.2) Instruction All workers shall wear Personal Protective Equipment (PPE) at all times, such as hardhat (helmet), safety shoes and working uniform.9.3) Prevention of Accident by Heavy MachineOnly skilled operator shall be allowed to operate equipment on site. In case of new operators, a test of skill shall be conducted first prior to his acceptance to the job. Preventive maintenance check shall be done regularly at equipment working at site prior to full operation. Stability of working area and foundation of equipment shall be checked particularly at locations of outrigger and track pad of cranes.9.4) Prevention of Accident of the Falling Object

During handling of materials and equipment, it shall be tied up properly to prevent from falling. Lifting wire ropes shall have designed capacity for heavy lifting. Lifting wire of lifting equipment such as crane shall be carefully checked.9.5) Prevention of Accident of ElectrocutionElectric generating equipment shall be properly protected and properly installed with earth connection. Electric wires shall be connected with electrical tapes to prevent electric leakage. Only skilled operator shall be allowed to operate equipment on site.

9.6) Prevention of Accident in Night Shift Works

Sufficient quantity of lighting system shall be provided for night shift works especially installed at working platforms. If necessary all of the surrounding working area shall be lighted up.9.7) Existing FacilitiesExisting facilities especially existing overhead electric line, water line, telecommunication line and other important facilities at surrounding area shall be taken with care not to damage. 9.8) Working platform

Working platform and access ladder shall be provided for work efficiency and safety as well.10. Environmental Control Environmental control shall conform to the approved - HSE PROGRAM. That Method Statement and shall be part of this method statement. Responsibility for surrounding environment during construction work and shall comply with the Condition of Contract and Vietnams National Law on Protection of Environment and other relevant legislation such as: Decision 55/2009/QD-UBND date 17/03/2009 on Establishing Regulation for Security, Safety and Eviromental Sanitation during Construction works in Ha Noi City.If any other problems occurred in the site, applicable counter measures or prevention action shall be considered immediately and executed as soon as possible.

APPENDIX Technical Trench - Construction Shop drawing title(File attached) EMBED Excel.Sheet.8

EMBED Excel.Sheet.8

Backfill and Cleaning up Site

Survey

(Location & Line marking)

Form Removal and Site Cleaning

Casting conerete Wall and Top Slab

Install Top Slab

Rebar and Form Assembly

(wall)

Install Cable Support & Grounding

Cast in Bottom Slab

Cast in lean concrete

Rebar and Form Assembly

(Bottom slab)

Survey

(Alignment + Level)

Excavation Work

PAGE Revision A1, 15th April, 2010page 1

_1384235592.dwg

_1468648696.xlsSheet1

No.Material forDescriptionDetailQuantityRemarks

Blinding Stone

?1BackfillExcavated Soil /SandConform to Chapter 7varies

?2Lean ConcreteClass E - Unreinforced Conc.

?3ConcreteClass C1Strength - M200 - Conform to Chapter 10

?4Reinforcing Steel barGrade 300, Grade 400Conform to Chapter 11

?5Angle Steel 80x80x7L80x80x7

_1468817273.xlsSheet1

No.NameDescriptionUse forRemarks

ExcavationBackfillingBox CulvertBlinding StoneConcreting

?1Excavator0.70 m306 ea

?2Dump Truck15 m306 ea

?3Bulldozer16 ton03 ea

?4Mini Compactor1 ton12 eaincl. Base compaction

?5Submersible Water Pump4 inches06 eaDewatering

?6Diesel Generator50 KVA03 eaLighting for nightwork

?7Lighting System03 lotNightwork

?8Survey Equipment03 ea

?9Minor Tools06 lotincl. Joint sealing

?10Concrete VibratorDia.(25~60mm)06 eaincl. spare

?11Formwork06 lotSteel form panel

?12Bending Machine03 ea

?13Cutting Machine03 ea

_1384235593.dwg

_1384235591.dwg

_1383992031.dwg