Biện pháp thi công mở rộng tuyến cống hạ tầng đô thị song ngữ bản English

Biện pháp thi công mở rộng tuyến cống hạ tầng đô thị song ngữ bản English 1. Giới thiệu về gói thầuKết cấu (Hố ga, CSO, cửa xả):Một hố tách dòng (CSO) cho lưu vực D sẽ được xây dựng tham chiếu theo bản vẽ LT2MS_OutD… Thêm vào đó 100 hố ga đặc biệt và điển hình sẽ được xây dựng tham chiếu theo bản vẽ LT13MSMHT… và LT2MSMHS… .Tuyến công chính:Ở gói thầu 2 các tuyến cống chính sau (cấp 1 và cấp 2) sẽ được xây dựng tham chiếu theo bản vẽ LT2MSPP…Tuyến cống cấp ba trong hẻm:Trong gói thầu 2 tổng chiều dài đường ống là khoảng 1.800 m sẽ được xây dựng trong tổng số ~ 15 hẻm theo bản vẽ LT2TNA .... Trong số 1.800 m khoảng 620 m là ống DN300 đến DN500 phải được lắp đặt trong giữa của các con hẻm và khoảng 1,400 m là ống DN200, cho đấu nối của một số hộp kết nối nhà dân đến ống DN300 đến DN500.Tuyến cống cấp ba trên đường:Trong gói thầu 2 tổng chiều dài là khoảng 6,350 m đường ống DN200 đến DN300 sẽ được xây dựng trên vĩa hè dọc theo các tuyến đường. Trong trường hợp có các chướng ngại vật ở vỉa hè ngăn cản xây dựng trên vỉa hè các đường ống sẽ được lắp đặt gần sát mặt của đường. Các khu vực chính cho thi công tuyến cấp ba dọc theo đường là lưu vực D, G, F và JN tham chiếu bản vẽ LT2TNS ....

SITE ORGANIZATION AND CONSTRUCTION METHODS

Name and form of Bidding: Extension of sewer systems

Bid package:

The Employer:

PART 1 – GENERAL INTRODUCTION

I INTRODUCTION TO THE BID PACKAGE

1 Introduction to the Bid package

Structures (Manhole, CSO, discharge outlet):

A flow separation outfit (CSO) for basin D shall be constructed as referred

Code Basin Point US PointDS Length Name of roads

Grade 3 sewers in alleys:

In Bid package 2, the total length of conduits is approximately 1800 m,which shall be constructed in a total of ~ 15 alleys according to Drawing LT2-TN-A- Of which 1,800 m, approximately 620 m including DN300 to DN500

is placed in the middle of the alleys and around 1,400 m is conduits DN200 forthe connection of some household connection boxes to conduits DN300 toDN500

Grade 3 sewers in roads:

In Bid Package 2, the total length is about 6,350 m for conduits DN200 toDN300, they shall be constructed on pavements along the road routes In thecase of pavement obstructions that prevent the construction on such pavements,conduits shall be placed close to the road surface Main areas for construction ofthe grade 3 route along the roads are basins D, G, F and JN as referred in theDrawing LT2-TN-S ;

2 Completion duration: 18 months

PART 2 – CONSTRUCTION ORGANIZATION

I Organizational structures of the Site:

Tổ CốT THéP

Tổ THI CÔNG

Số 1

Tổ thi công

số 2

Tổ thi công

số 3

Tổ BÊ

TÔNG

Tổ CốP PHA

bộ phận kỹ thuật hiện

tr ờng

bộ phận quản lý chất

l ợng

bộ phận hành chính

bộ phận

đảm bảo an toàn

bộ phận thí nghiệm

bộ phận quản lý môi

tr ờng

II Description of organizational structures of the Site:

* Project Manager:

The Project Manager is the highest decision-making person and directly

to units in the Site for effective performance of provisions under economiccontracts The Manager shall have the right to coordinate the progress schedules,general construction quality at the site for arrangement and adjustment of tasksamong units, coordinating works, mobilizing equipment and materials in the site

in accordance with capacities of the units as well as ensuring the progress

* Superintendent:

Be fully responsible for implementation and assurance of the quality andefficiency Directly providing orders to construction units as well as ensuring therelationships with supervisors of the Employer and design agency

* On-site Technical Department:

Under the management of the Superintendent in terms of constructionperformance and construction management, including: method planning andimplementation of construction measures

* Quality Management Department:

NG DEPARTME

NT

QUALITY MANAGEM ENT DEPARTME NT

ADMINIS TRATIVE DEPARTME NT

SAFETY SECURITY DEPARTME NT

LABORATOR

Y DEPARTMENT

ENVIRON MENTAL MANAGEME

NT DEPARTME NT

SURVEY

TEAM TE TEAMCONCRE REINFORCED

CONCRETE TEAM

SCAFFOL DING TEAM

CONSTR UCTION TEAM 1

CONSTR UCTION TEAM 2

CONSTR UCTION TEAM 3

Quality Management Department shall manage all issues within the scope

of contracts relating to the quality, such as:

- Organizing the quality management system for the site

- Preparing project quality assurance plans and implementation monitor

- Coordinating with the Employer, partners to supervise the qualitymanagement of works, ensuring the quality of the package

* Safety Security Department:

In charge of guiding, supervising and making the first-aid in case ofaccidents at the site through the first-aid stations Ensuring the labor safetyactivities as required in the contract and this requirement

- Preparing detailed construction safety plans during the construction tosubmit to the Employer for approval and implemented during the constructionperiod of the bid package

* Laboratory:

The Laboratory shall be responsible for testing and inspecting the quality,this Department is equipped with a full range of test equipment, measuringdevices relating to the objects to be tested

Material Testing Department and Quality Inspection Department haveproper work-related equipment to control the quality of inputs from othersuppliers

* Environmental Management Department:

Environmental Management Department is responsible for guiding andsupervising construction activities that affect the environment according torequirements of the Project

- Environmental Management Department shall, on behalf of theSuperintendent, disseminate all directives and instructions related to theenvironmental impacts according to requirements of the Project

* Department of materials, equipment and storekeeper

Department of materials, equipment and storekeeper is responsible forsupplying materials and equipment to ensure that the construction items are inaccordance with the design, procedures, current regulations as well as meet thehighest requirements of the construction progress and quality of the works

III Layout of construction site:

The Contractor shall undertake the study of approved documents and receive the landmarks, elevation piles Based on actual conditions, the

Contractor shall compare with the design documents, in case of defects, the Contractor shall submit to the Employer and Engineers for review and repair according to actual conditions at the Site

Each specific duty shall be prepared in advance as planned to avoid

overlapping works and ensure the construction progress as required

The Contractor plans to arrange 01 Site Management Board, site-huts in convenient areas for the purposes of construction

Auxiliary works include: Headquarters of the Project Management Board

of the Bid Package, houses for staff, workers, information and living facilities,sports and entertainment facilities, material storehouses and gathering yards ofmaterials, construction equipment etc

Based on the actual terrain conditions, the Contractor plans to execute theworks in a sequential way according to the progress assurance procedures andthe quality of the works

The work items of the Project Management Unit are constructedalternatively Include the following construction teams:

+ Survey team

+ Reinforced concrete team

+ Scaffolding team

+ Concrete construction team

+ Construction team of conduits including: construction team No 1, 2,3…

IV Arrangement of signs and barriers

To ensure environmental sanitation

To ensure labor safety for people, construction equipment and works

To place signs, traffic signs, mobile barriers at the site to prevent people,means and animals from accessing to the item

V Supply water and power for construction

* Power sources

Power sources are connected from the local power grid Electric wires arerubber cables Main circuit breakers and meters are installed at the powersources Power transmission lines are connected along to the fences TheContractor uses two 50KVA back-up generators to supply the power

* Water

Water for construction and firefighting is taken from wells to preventlong-term water loss

VI Material sources:

All materials used at the site must meet Vietnamese standards with qualityregistration of the manufacturer

The Contractor undertakes that all types of materials used for the worksshall be submitted to the Engineers regarding to the sources of supply andmust be thoroughly tested in accordance with the requirements as stated in theBidding Documents and approved by the Employer

(Sources of materials are based on legal documents)

List of materials used for the construction

TCVN 6016-1995; TCVN6017-1995; TCVN 4030–85; TCVN 141 : 1998

5 Types of uPVC conduits and

reinforced concrete culverts

Current Vietnamesestandards

- TCVN 9398:2012 : Surveying in construction - General requirements.

-TCVN 4447-2012: Earth works - Construction, check and acceptance;

-TCVN 9394:2012: Pile driving and static jacking works – Construction, checkand acceptance;

-TCVN 8859 -2011 : Graded aggregate bases and subbases pavementspecifcations for construction and acceptance;

-TCVN 8859-2011: Specification for Construction of Hot Mix Asphalt ConcretePavement and Acceptance;

-22TCN 247-98: Construction standards and acceptance of prestressed concretebridge beams;

-TCVN 5308 -1991: Technical regulations on Safety in Construction

-TCVN 5674:1992 Finised works in construction – execution, check andacceptance;

-TCVN 1771 – 1986 : Gravel, crushed gravel used in construction - Technicalrequirements;

-TCVN 4314 -1992: Mortar for masonry – Specifications;

-TCVN 4452:1987: Kết cấu bê tông và bê tông cốt thép lắp ghép – Thi công vànghiệm thu;

-TCVN 4453 -1995 : Prefabricated concrete and reinforced concrete - Codes forconstruction, check and acceptance;

-TCVN 9202:2012: Masonry cement;

-TCVN 4085 – 1985: Brick, stone structural - Codes for construction, check andacceptance;

-TCVN 5640 -1991: Hand over of building works - Basic principles;

-TCVN 4252 – 1988: Procedures for formulation of the building organizationdesign and the building works design Construction regulations and acceptance;-TCVN 2287 -1987: Labour safety standards system - Basic rules;

-TCVN 4086 -1985: Electrical safety in construction – General requirements;-TCVN 3255-1986: Explosion safety- General requirements;

-TCVN4244 – 1986: Safety regulations of heavy equipment;

-TCVN3254-1989: Fire safety- General requirements;

-TCVN 3508 – 1991: Technical regulations on safety in construction;

- And other current standards and regualtions;

PART 3 – GENERAL CONSTRUCTION METHODS

A/ PREPARATION:

1 Taking over the site and inspection

The Contractor shall take over the site after the Employer decided to handover the site The process of taking-over and handover of the site shall beattended by all stakeholders including Employer, Design Consultants, Engineer,Constructor and cadastral management units

After handing over the site, the Contractor shall receive the landmarks,including the boundary landmarks of the bidding package, landmarks of landclearance, landmarks of construction corridor, design landmarks, landmarks ofdesign elevation and piles, if any), (central piles, curve piles, edge piles of talusetc.);

After taking over the site and landmarks, the Contractor shall checkcurrent status In case of any difference between the current status and thedesign, the Contractor shall submit to the Employer and Engineer for review andrepair in accordance with current status

Constructing barriers, signs at the Site for each location

Determining the elevation and driving piles for each work item

2 Construction of site-huts, gathering yards of materials and equipment

Based on the current site, natural conditions, climatic conditions,surrounding infrastructures and construction volume of the Bid package, theContractor shall make specific calculations to arrange and construct site-huts,gathering yards etc in the most reasonable manner

Construction works include the Headquarters of the Project ManagementBoard of the Bid Package, houses for staff, workers, information and livingfacilities, material warehouses, gathering yards of materials, constructionequipment etc The Contractor shall level these auxiliary works and backfilled

by ballast with the thickness of 15cm and covered with mortar M75 with thethickness of 3mm

For the access roads, the Contractor shall execute ballast with thickness of15cm for the construction works

Power sources for production and daily life are connected from currentsources used for the construction site To prevent any interruption, theContractor shall reserve 02 generators

The water sources used for production and daily life are from the currentwater sources The Contractor shall use tankers to transport water to locations

where water is not available.

3 Management, relocation and positioning of piles at the Site:

For piles, stakes, important details within the construction site, theContractor shall apply measures to move to other locations and preparepositioning plans without changing during the construction process

After completing the management plan for reallocation of piles, theContractor shall hand over a set of documents to technicians and Engineers forsupervision during the construction process

4 Preparation and gathering of materials

Based on construction volume, requirements of works and constructionprogress of the Bid package, the Contractor shall prepare and gather materialaccording to types, quantity and time of use

The Contractor shall mobilize materials and supplies based on thematerial mobilization schedule for the bid package

The Contractor shall use high-quality materials and supplies inaccordance with requirements of the Bid package and current regulations andstandards of the State

The Contractor shall only use materials and supplies for the Bid package

in case of the quality certificate Before use, materials and supplies must betested and approved by the Employer and Engineer

The Contractor shall prepare sufficient quantity of materials to ensurefully and timely supply

5 Preparation of construction equipment

Based on construction volume, requirements of the works andconstruction progress, the Contractor shall prepare and gather constructionequipment according to correct types, quantity and time of use

The Contractor shall use modern machinery, equipment with highcapacity to meet requirements of the works Prior to use, machinery andequipment must be approved by the Employer and Engineer

To meet the continuity of the works, guarantee the quality andconstruction progress, the Contractor shall reserve equipment and machinery Incase of failure, machinery and equipment must be stopped and replaced byothers

6 Preparation of construction procedures

* The Contractor shall submit to the Employer the following procedures:

+ Project performance method.

+ Quality management plan

+ Use plans of materials and supplies

+ Origin of materials

+ Mobilization and use plans of construction equipment and machinery.+ Features and capacity of equipment used for the bid package

+ Use plans of material mines (if any)

*The Contractor shall notify the Employer’s preparation of procedures as follows:

+ Construction permits

+ Notice to power and telecommunications companies to identify thelocation of cables in the construction area

+ Construction site map and traffic flow solution

+ Location map of temporary storages

+ ESHS method (as stated in the Bids)

+ Other required materials relating to the additional construction works (ifany);

* The Contractor shall apply for water and power supply, installation at the Site.

* The Contractor shall contact to local authorities to apply for the temporary residence of all personnel involved in the Project.

* The Contractor shall carry out procedures to transport materials and equipment to the Site.

7 Construction and installation of formworks

The Contractor shall use steel, word formworks or Fuvi plastic formworksduring the processing process of formworks Faces of formworks are guaranteed

to be flat and smooth as required

Formworks shall have the same thickness In case of using laminatedwood, the thickness shall not less than 12mm and waterproof sealant shall beused in the fabrication

Formworks shall have correct structures corresponding to the shape ofconcrete blocks as detailed in the drawings Formworks are designed properlywith strong structures and be approved by the Employer In the design andconstruction of formworks, the Contractor shall consider the shrinkage,deformation or deflection during the construction process to adjust in order to

ensure that the dimension of concrete blocks is consistent with the straightness,elevation and curvature.

Do not concrete without prior approval of concrete-related works such asthe installation of reinforcing steels, steel anchors or pre-stressed steels as well

as other written documents relating to the formworks of the Employer

The formwork removal is performed when the concrete strength reaches

at least 75% as for wall formworks and 100% as for bottom formworks

8 Construction methods of reinforcing steel:

* Processing of reinforcing steels

The reinforcing steels are cut and bent to the forms as shown in theschedules Tolerances shall be consistent with the standards All steel bars shall

be cold bending, unless otherwise provided Steel bars buried in concrete blocksshall not be bent, unless otherwise provided in schedules or approved

Sizes of anchor hooks and bending diameters measured inside of the steelbars shall be determined according to parameters shown in the plan If the size

of anchors or bending diameter is not shown in the drawings, provisions of Part

I, Article 8.23 “Construction code - Requirements for reinforced concrete” shall

be applied

Each reinforcing steel shall be cut and bent to the size as specified in theDrawings For some structure, the number and length of steel bars may need to

be measured at the site to be consistent with the size of the structure

As for the bending of reinforcing steels, recommendations of themanufacturer shall be complied with in each case All steel bars shall be coldbending All reinforcing steels shall be bent according to procedures of theAmerican Concrete Institute, unless otherwise specified Steel bars insideconcrete blocks shall not be bent, unless otherwise specified on the Drawings orallowed

Authorized person shall cut and bend steel bars and use proper equipment

to do so

* Installation of reinforcing steels

Reinforcing steels are assembled according to shapes and sizes as shown

in the Drawings Bars are tied together firmly at intersections to form a solidframe and fixed during the concreting process Steel wires are not allowed to beloosen in the surface of concrete

Concrete blocks and fillers must ensure the strength to avoid the breaking

or cracking during the concreting They are fabricated as small as possible andkept in fixed places by wires These blocks are soaked into the water just beforeconcreting

The temporary support bars for reinforcing steels shall not be put intoconcrete blocks without permission of the Employer

When concreting, all reinforcing steels must be cleaned and removedthoroughly all liquid detergent, scale, mud, oil or any other coatings that maydestroy or reduce the binding; these steel structures must be cleaned the whole

or any part for a specific equipment as stated in the notice of concrete

The minimum distance of parallel steel bars is 2.5 times higher thediameter of the steel bars; if the distance is not specified clearly, the distancebetween bars shall not less than 1.5 times the maximum dimension of materialsused for concreting

All reinforcing steels must have a protective layer as shown in theDrawings Steel bars shall be placed on concrete fillers (prefabricated) with thesame Mac with the concrete used for the structures; the thickness of these fillers

is as same as the thickness of the protective layer

Protective layers, general limits on reinforcing steels and distancebetween them shall be complied with regulations as stated in the Drawings

9 Concreting:

* Concrete aggregate:

After receiving a written approval for materials, the Contractor shallsubmit the Employer a written design of concrete aggregate

The Contractor shall strictly comply with minimum compressive strength

of testing blocks after 3 and 7 days After obtaining testing results, theContractor shall submit a written request to require the Employer to approve thedesign of concrete aggregate The concrete is only carried out when theEmployer approves the design

* Concrete testing

- Testing of concrete strength.

Before concreting, the Contractor shall submit to the Employer with aConcrete sampling plan

The concrete testing shall be carried out by an independent laboratory asappointed or approved by the Employer with consultancy of the Contractor

The sampling is implemented at the Site with presentation of theEmployer’s representative.

Numbers of concrete strength samples are determined as follows: Aconcrete sample is taken for every 50m3 Samples are marked with serialnumbers and time, work items and any other information as required Thensamples are sent to the certified laboratory

If 7-day testing results fail to meet requirements, the Contractor shall,under the Employer’s guidance, carry out testing and inspection for suspectedstructures If the testing results prove that concrete blocks don’t meetrequirements, the Contractor shall demolish damaged concrete and reconstructsuch structures

The testing results shall conform to current standards

- Technical workers shall have skill grade 3 or higher

- Workers in charge of transporting materials for concreting shall be skillgrade 3

- The construction process is implemented comprehensively and properly.Materials are prepared properly with good construction equipment Theconstruction process shall be executed continuously until all technicalspecifications are met

In case of rain, nylon films are used to cover the entire concreting areas

In hot weather conditions >300C, canvas are used to cover to avoid directsunlight after concreting

Concrete slump test (flexibility): Using Abrams equipment to measure theslump

After concreting, concrete blocks shall be covered and maintainedaccording to current construction regulations

*Mixing concrete by concrete mixers:

The mixing and transport of concrete is carried out in accordance with therequirements of applicable standards The mixing and transport of concrete shall

be regulated to ensure that the concreting process is implemented in acontinuous status The time of each concreting shall not be too long to voidpartly solidification, that period shall not exceed 45 minutes

The addition of water or additives shall not be carried out without priorconsent of the Employer; however, the ratio of water-cement should not exceedthe regulations

Concrete mixers shall be operated at the speed as indicated on themanufacturer’s nameplate Any concrete batch that the mixing time is shorterthan the specified time shall be disposed or removed by the Contractor

Water shall be added to the drum before cement and aggregates are added.Water is added regularly and all water volume must be added to the drum untilthe end of the first 15 seconds of mixing Approximately 10% of the watervolume required for the mixing batch is put into the drum before cement andaggregate are added, while the remaining water volume is gradually added to thedrum so that all water volume is added within the first 1/4 period of time of themixing The mixing time shall not less than 60 seconds for the mixer withcapacity of 1.5 m3 or less For mixers which have a capacity higher than 1.5m3,the mixing time shall not less than 90 seconds If the start time to set up themixer to the maximum capacity, further 4 seconds are calculated to the mixingtime The mixing time is completed with the feeder is opened The concrete ismixed until the mixture has a homogeneous color and the consistency isattained

The amount of concrete in a batch shall not exceed the rated power of themixer All concrete of a mixing batch shall be taken away before materials areadded for a new mixing batch After completion or there is any interruption formore than 20 minutes, the mixer and other equipment must be cleaned withwater If concrete is still remained in the mixer, it must be cleaned by rotatingthe aggregate and water in the drum before mixing the fresh concrete

The mixed concrete as stated above shall not be changed by adding water

or any other ingredients

Concrete added into the drum within one hour or stated to be solidifiedshall not be used

The slump of concrete will be measured according to current standards

Formwork shall be treated with anti-corrosion materials or saturated waterbefore concreting Open formwork surfaces shall be treated with an anti-corrosion agent to prevent the adherence of the concrete and must be approved

by the Employer

The concreting work shall be carried out carefully with the height of lessthan 1 meter The outer surface shall be thoroughly cleaned during theconcreting process by using approved tools and equipment This work includesthe removal of large-size aggregates out of the surface, separating the mortar inthe formworks to form a flat surface without water, air bubbles or honeycombs

The Contractor shall concrete by mixers

The concreting work shall be implemented so the water is notconcentrated to a corner or formwork surface; it is not allowed to add a largevolume of water in a specific period of time and remaining water must run alongthe formworks

All concrete should be poured and compacted in layers and bonded withprevious concrete layers The thickness of concrete is varied from 15 to 30 cm

as for reinforced concrete and up to 45 cm for non-reinforced concrete

* Compaction of concrete

Concrete shall be compacted continuously and carefully; especiallyaround the reinforcement parts and at corners of formworks so that the concrete

is tightly bonded and contains no honeycomb

Concrete is compacted by plate vibrators or spud vibrators according torequirements of the Employer Do not use vibrators to compact concrete withtoo high vibration

All compactors shall have a proper diameter according to the distance ofreinforcing steels with sufficient frequency and carried out by experienced

personnel Concrete shall be compacted at regular distance which isapproximately 10 times higher than the diameter of the vibrators and same depth

in the concrete The vibration works shall be implemented carefully to avoid anymovement of reinforcing steels or effects on the solidified concrete Theequipment shall not be attached to the reinforcing steels in any case Eachcompaction time shall be carried out continuously until there is no air bubble onthe concrete surface, but shall not exceed 30 seconds The vibrators shall beremoved slowly and in the vertical direction to ensure that no air bubble isgenerated

The concrete shall be compacted by vibrators as approved by theEmployer Whenever necessary, vibration works shall be supplemented byshovels or suitable tools to ensure proper compaction

The Contractor shall prepare the back-up equipment during theconcreting

All works of compaction and completion shall be completed right afterconcreting

Workers are not allowed to walk on the surface of new concreting layersuntil they are solidified to bear the weight without distortion

It must pay attention to avoid any exposal of reinforcing steels out of theconcrete surface The original structures of concrete exposed to reinforcingsteels shall not be demolished or damaged by the vibration

The concreting in any structure or part shall be carried out continuouslywithout interruption In case that beams and plates are an integral part ofstructures, they shall be concreted in the same phase

All newly-placed concrete shall be maintained, and this maintenance shall

be commenced immediately after finishing the concreting and maintaining for atleast 7 days The purpose of maintenance is to ensure the moisture of concrete

The Contractor's maintenance methods shall be approved by theEmployer The Contractor shall apply the following maintenance methods.

10 Construction and erection of main sewers

- Determining the central lines of sewers, locations of manholes

- Installing temporary fences, safety equipment

- Locating the excavation works

- Executing the road works

- Removing the surface layers of roads

- Executing the reinforcement

- Excavating

- Repairing manholes by manual

- Driving cajuput piles

- Executing sand layers

- Executing culverts and joints

- Filling sand and compacting

- Completing and handing over the site, acceptance;

In each construction phase, the site organization and equipment for theconstruction shall be arranged according to main equipment and themobilization of human resources for that phase

11 Construction and erection of uPCV conduits

- Executing road bases

- Executing ditch canals for placing culverts

- Laying sand of conduits and installing uPVC conduits;

- Implementing the connection and welding of conduits

- Testing pressures, excavation and filing sand;

- Constructing and returning the site and acceptance;

12 Construction of manholes

- Determining the central lines of manholes

- Erecting temporary fences, safety equipment

- Locating the excavation works

- Executing the road works

- Removing the surface layers of roads

- Executing the reinforcement

- Excavating

- Repairing manholes by manual

- Driving cajuput piles

- Executing sand layers

- Executing the bottom concrete plates

- Executing bottom concrete, wall concrete and concrete covers

- Completing and handing over the site, acceptance;

13 Progress guarantee

The construction progress guarantee is a very important work Prior tothe construction, the Contractor shall contact with the local power and watersuppliers to provide water and power for the construction of works

The construction equipment is arranged fully and in accordance withconstruction methods The construction site is close to other sites of theCompany, so that in case of failure of any equipment, the Contractor shall useother equipment to guarantee the construction progress In addition, theContractor shall also provide some additional equipment

The Contractor shall arrange qualified and experienced human resources

in accordance with the arrangement

The construction equipment is repaired and maintained regularly to avoidany damage during the construction process

However, the most important thing is to ensure the orders, combinationand proper succession between the construction progress and work items TheContractor shall cooperate with Employer, Engineers and other constructionunits to ensure the most effective construction Technical requirements andgeneral construction progress are guaranteed The construction in specific orders

is the most reasonable solution

Based on the volume and requirements of the progress, all forcesincluding machinery, equipment and personnel at the site shall be arrangedproperly to perform the bid package in the most effective ways

Based on the current status of the construction area

Based on the weather and climate conditions at the construction site

Based on construction capacity and experience, the Contractor shallprepare construction schedules for the Bid package with the total constructiontime from the commencement date to the date of delivery is 18 months

PART 4- DETAILED CONSTRUCTION METHODS

I Construction methods of reinforced concrete culverts and uPVC conduits

1 Construction procedures

Prior to the construction, the Contractor shall train all technicians andconstruction workers regarding to the construction procedures of conduits in anorder as specified in the diagram Based on the site conditions according to theorganizational diagrams, the Contractor shall disseminate the specificconstruction process to each site

2 Site preparation

* Site preparation

The Contractor shall agree and hand over the site to units who haveunderground works in the construction site of the Bid package, and hand overthe site in writing between the parties under the witness of the PMU

The Contractor shall prepare detailed construction plans and constructionschedules, so that units who have underground works and surrounding peoplewill acknowledge and then facilitating the construction of culverts in such areas.The Contractor shall prepare and gather all necessary elements such aslights, electric cables, equipment, motorcycles etc for the construction;

Based on construction capacity in the day, the Contractor shall execute theconduits to avoid any impacts on the traffic and daily life of people in the area.The execution of conduits and culverts are only carried out with theapproval of the Employer and full of construction permits

Auxiliary parts are also lifted by turbo-cranes, arranged in trunks, notthrown and overlap when transporting to the site

* Determination of central lines for erection of culverts, conduits and benchmarks

- Determination of central lines

Based on the position of each pile (as marked on the drawings) and based ondelivery documents of the Employer and Contractor, the Contractor shall drivewooden piles or iron poles to position all piles along the edges in order todetermine the central lines

Based on such central lines, the Contractor shall locate the benchmarks fromdesign piles with the distance of 1 benchmarks for every 30 - 40 piles Thecentral lines of benchmarks are transferred from other benchmarks asdetermined by the leveling instrument and the Contractor is responsible forpreserving such benchmarks during the construction process and serves theinspection and testing works

Use white paints to paint asphalt roads or concrete surfaces

- Determination of elevation of ditch canals, bottoms and culverts

The determination of elevation of conduits is important when placingculverts and conduits and the hydraulic slope Through many years ofexperience, our Company has applied the methods as follows

+ From the standard elevation according to the design of the Employer, theContractor shall transfer the elevation to construction site, determine theelevation to the construction area and elevation to power poles or other fixedpositions of the local houses on road sides where conduits are constructed, orother fixed elevation near to the first pile, along to the ditch canals; in widespace without fixed items, wooden piles are driven with distance of 4x4x50,elevation distance is <25m to facilitate the construction process

+ After that leveling machines are used to determine the elevation of groundfor executing the ditch canals, depth and erection of culverts and conduits

- Benchmarks for inspection

The construction of conduits and culverts is within an areas as same as otherworks, therefore the determination of elevation not only minimizes the revisionbut also greatly affects the progress of excavation and construction

Conduits and culverts are divided into many construction areas and executed

at the same time; therefore, it must have many benchmarks subject to the terrainconditions, the distance of among benchmarks is 50m and 100m for inspection.Benchmarks are built by concrete or iron piles or in fixed structures, marked

by paints or by concrete with iron nails

3 Excavation of ditch canals and treatment techniques

* General methods

Prior to executing ditch canals for placing water sewers, the Contractor shallarrange signs, barriers, lights at night etc The ditch canals and sewers areconstructed in successive construction method, executing with the length of L =50m, then inspecting the ditch canals to meet requirements in the Technicaldocuments

Works of execution of ditch canals and culverts shall be executed in thefollowing steps:

* Step 1: Determination of culverts and sewers

- Determining central lines, conduits and marking by paints or limes orboundary lines

- Identifying the elevation of each culvert section by theodolite, Electrictachometers

* Step 2: Executing ditch canals

- At narrow areas of culverts and conduits, that are difficult to access bymotorcycles, the main construction method is by manual In convenient areasclose to large roads, suitable for the transport of machinery and equipment, theContractor shall use excavators with bucket capacity of 1.2m2, in combinationwith manual repair methods.

- For single or double ditch canals with slopes, the Contractor shall executeditch canals according to the design drawings and the Bidding documents asprescribed

- Execution of vertical ditch canals: The clearance width of ditch canals withvertical edges shall not less than or exceed 10% of the width of the clearance

- During the construction, the Contractor shall pump and discharge water tospecified areas to avoid the flooding and obstruction to the traffic systems or anyimpacts on the surrounding environment

* Step 3: Inspection of ditch excavation

- Before erecting the culverts and conduits, it must inspect the slope,dimensions by the theodolite, Leveling instrument and other special tools Thesewer bottom must ensure the flat and dry

- The depth of ditch canals is consistent with the design, slope of conduitsand not exceed 15% of the slope shown in the drawings All special cases shall

be consulted and approved by the Engineers

Some permissible tolerances for executing conduits shall be according torequirements of the Employer

* Step 4: Backfilling

- Soil used to fill ditch canals must be neatly arranged and not cause anydanger and obstruction to the traffic as well as daily activities of local people.Excess soil is transported by trucks and covered by canvas to the landfill at therequest of the Employer and competent authorities

* Step 5: Sand layers

- Filling sand layers with the thickness of 200mm for culverts and conduitsand then using vibrators to compact to the required compaction

Note: After executing the ditch canals, the Contractor shall place iron sheets

to cover the foundation pits to ensure the traffic safety

* Acceptance of the execution

After completion of the excavation, the Contractor shall cooperate with theEmployer and Engineer to accept foundation pits to transfer next works; basesfor acceptance are as follows:

+ Approved drawings of ditch execution

+ Elevation and size of current pits