Method statement for pipe culvert

Biện pháp mô tả chi tiết quy trình thi công hạng mục cống tròn bê tông cốt thép. Biện pháp được biện soạn dựa trên chỉ dẫn kỹ thuật dự án, tiêu chuẩn AASHTO

III ORGANIZATION CHART 6

IV MANPOWER AND EQUIPMENT 7

1.Manpower 7

2.Equipment 7

V MATERIALS 7

1.Bedding 7

2.Concrete for culvert and headwalls 7

3.Bar reinforced for culvert and headwalls 7

VII QUALITY CONTROL 11

VIII SAFETY CONTROL 11

IX ENVIRONMENT CONTROL 12

1 Ambient air quality 12

2 Noise and vibration level 12

3 Water environment 12

4. Waste management 13

X APPENDIX 13

I.GENERAL DESCRIPTION1 Introduction

This method statement provides the details of the procedure, the manpower, the equipment, thematerials and relevant documents related to construction pipe culvert including the quality controlverifications, the measurement verifications, and also the safety precautions and environment protectionto be implemented for this work

2 Project Information

The project road connects Tbong Khmum district to Kratie province of the Cambodia, stretching alongthe northern, to Kratie province The road passes on a comfortable alignment through flat/wavy terrainalong the toe of hilly land Four (4) rather sharp curves along the road are considered non-critical due toadequate super-elevation of the road way and appropriate signage The traffic on the road is a mediummix of private cars and quite heavy trucks that contribute mainly to the road wear The PR.377 andPR377A of RCIP are located in Kratie province The length of the PR377 is 35.00 km and the PR377Ais 13.593km The location of the packages is shown in Figure-1

Figure 1: Location of Contract Package on CW-3(PR377 & PR377A)

3 Project Objective

The objective of the project is to ensure continued effective use of the rehabilitated national andprovincial road network in support of the economic development in Cambodia It will do so byimproving the institutional and technical capacity of the Ministry of Public Works and Transport forroad maintenance planning, budgeting and operations as well as by expanding of strengtheningmaintenance activities

The project seeks to contribute to cultivating a road asset management culture within the sector by: (i).expanding maintenance of the national road infrastructure nationwide and facilitating interventions inpriority areas, (ii) allocating adequate maintenance funding during the budgeting process; (iii).knowledge building in MPWT on road network management, maintenance technology and contractmanagement; and (iv) private sector involvement in competitive bidding and performance quality.Project is expected to bring significant benefits to local residents in six Cambodian provinces, Kampongchham, Tbong Phmum, Kratie, Mondulkiri, Ratanakiri and Stung treng province; by reduced traveltimes and cost, less arduous journeys and better connectivity along the national road network It isintended that the benefits to local populations are maximized, and to ensure that the benefits are sharedby local communities.

4 Topography and Climate

The topography in the project area is mainly flat with some hilly sections and the road elevation variesfrom minimum 23.52m to maximum 50.95meter The maximum temperature is around 40°C, the annualtemperature fluctuates more than 10°C and from 6 – 7°C in a day In hot weather the absolute hightemperature may be up to 39°C (in April) By contrast, in January the absolute low temperature maydescend to 16°C

5 Rainfall Records

The available hydrometeorological data such as rainfall are obtained from the Kratie ProvincialDepartment of Water Resources and Meteorology (PDoWRAM) The rainfall station is located at(X=610976, Y=1379728) The data ranged from 1980 to 2019 is considered to conduct frequencyanalysis for hydrologic modeling The 24hr maximum annual rainfall over 3 decades were extracted forthe analysis as shown in Figure 4.1 and 4.2 below From the figure below, it’s clearly observed that thehighest rainfall over the period was in the year of 1988 with a value above 250mm, followed by the yearof 1982 as the second highest with the precipitation of above 270mm The year 2009 is observed to haveabove 150mm which was the highest rate over the 10 year after 1992 and it was revealed during theKetsana storm In 2001 was noted as lowest rainfall, it’s reflected to the Drought period

Figure 1.5-1 Daily Rainfall Ditribution in Kratie 1980-2019

Figure 1.5-2 Rainfall Distribution over 1980-2019

II DESCRIPTION OF WORKS1 Scope of Works

 This item includes works related to the completion of a drainage pipe culvert such as: Surveying theconstruction area; excavation of foundation pit; construction of foundation layer; installation of pipe,construction of outlet, inlet, backfill material for pipe culvert and other works

Table 2.1-1: Schedule of cross pipe culvert (CW3-PR377)

Table 2.1-2: Schedule of cross pipe culvert (CW3-PR377A)

 Detail list as shown on contract drawing+ Design length of PC D1000 = 472.50m (PR377)+ Design length of PC D1000 = 129.00m (PR377A)

2 Standards and technical specification related

a Standards related

AASHTO, 2002 Standard Specifications for Highway BridgesAASHTO T280 Standard Method of Test for Concrete Pipe, Manhole Sections, or TileASTM C 76M Standard Specification for Reinforced Concrete Culvert, Storm Drain, and

Sewer PipAASHTO T27 Sieve Analysis of Fine and Coarse AggregatesOther Standards related

b Technical specification

+ Section 5.1: Concrete of Specifications+ Section 5.2: Reinforcement of Specifications + Section 6.1: Reinforced concrete culvert pipes

3 Construction Schedule

Construction Schedule shall be referred to latest approved Schedule

III.ORGANIZATION CHART

Organization Chart is as follow:

IV.MANPOWER AND EQUIPMENT

For the construction of pipe culvert, the Contractor will divide into the construction sections, eachconstruction section will be mobilized personnel and equipment as described following

V.MATERIALS1 Bedding

Granular material to be used as bedding shall conform to the requirements as specified in Section 5.8of Technical Specification - Porous Backfill Material Type A, or similar material approved by theEngineer, and shall be compacted in layers not exceeding 100 mm thickness to a density not less than90% of that determined by AASHTO T 180, or such other standard as shall be directed on theDrawings or by the Engineer

2 Concrete for culvert and headwalls

Concrete culverts and headwalls for pipe culverts shall be constructed as shown on the Drawings inaccordance with the requirements of Section 5.1 of Technical Specifications

3 Bar reinforced for culvert and headwalls

Steel reinforcement for culverts and headwalls shall be as shown on the Drawings and in accordance tothe requirements as specified in Section 5.2 of Technical Specifications

4 Mortar

Mortar for joints shall contain one part portland cement and two parts sand by dry volume unlessotherwise required by the Drawings or these Specifications The sand shall conform to therequirements of AASHTO Standard Specification M 45

All mortar shall be used within 30 minutes of adding the water

Construction of Inlet and OutletInspection

embankment

Cleaning up of siteLaying/Installation of R.C Pipe Inspection of Location, alignment and elevation

Backfill and compaction

Refer to Approved method statement of

embankment

Inspection of R.C Pipe Dilivered on sitePlacing of bedding material bedding material, confirm of approved materialInspection for dimension and elevation of

Survey Marking for Base corner/ Surrounding

Pouring Blinding concrete/ Surrounding

concrete

Inspection for dimension and elevation of blinding concrete, confirm of approved materialSurvey and Setting out

Survey Marking for Base corner/ Bedding

2 Construction Methoda) Setting Out the Work, Staking and Surveying

Setting out, staking and surveying shall complement as shop drawing approved

Surveying tolerances Survey tolerances shall be as detailed below.

(mm)

Vertical(mm)

b) Excavation works

 The Contractor shall carry out any excavation and preparation of trenches for pipe culverts that may berequired in accordance with the provisions of Teachnical Specification The Contractor shall beresponsible for all dewatering and temporary support works of the trenches and all other necessarytemporary works that may be required during construction

 First step of excavation shall be undertaken using excavating equipment Bottom of excavation shallbe up to 20cm average above the designed bottom of structure excavation Depths shall be checkedand monitored carefully to prevent damage and disturb the subsoil of foundation

 Pumping pit may be provided located at one or two corners inside the excavation area Temporarydrain canal sloping towards the pumping pit may be provided around the perimeter of the excavationpit and shall be constructed outside the perimeter of the blinding stone

 Excavated materials found to be suitable for backfill and embankment shall be hauled to a designatedarea and shall be protected to keep dry Unsuitable materials upon approval by the Engineer shall bedisposed separately The vertical sides of the excavation shall be sloped approximately to a minimumof 1:1 for good stability The slope shall be properly covered with plastic sheet against soil collapseand erosion during rainfall

 Second step is manual trimming, leveling and excavation shall be done on the remaining 20cm averagefrom the first step of excavation up to the designed bottom elevation of structure excavation The baseshall be compacted using a portable compacting machine or equivalent In cases that unsuitable or softmaterial still exists at the designed bottom elevation of excavation, removal and replacement of suchwill be checked and confirmed by the Engineer

 After completion of excavation, all loose and displaced material shall be removed, leaving a neatly andsolid finished bed for construction of base of pipe culvert

c) Construction for bedding material ( if any)

 Determined limit of boundaries of bedding material indicated in shop drawing by stakes. Approved material for bedding material shall be placed following the approved shop drawing The in-

placed bedding material shall be compacted thoroughly to the satisfaction of the Engineer usingportable compacting equipment or equivalent

 Completed bedding material shall be inspected and approved by the Engineer prior to pouring blindingconcrete

d) Construction for blinding concrete/ Surrounding concrete (bottom level)

 Determined limit of boundaries of bedding material indicated in shop drawing by stakes. Approved material for blinding concrete shall be poured following the approved shop drawing. Completed blinding/ Surrounding concrete shall be inspected and approved by the Engineer prior to

laying or installation of RC Pipe

e) Fabrication and delivery of RC pipes

 RC pipe shall be pre-cast and Approved by engineer before transporting it to the site After Castingand Curing, RC pipe shall be handled with care and delivered on site Use crane to load and downsegment of precast to car and transport to the site They must be free of damage and shall be inspected

 Profile of factory, technique and procedure of fabrication for RC pipe in these factories shall besubmitting separate document.

f) Placing reinforced concrete pipes culvert

 Use crane or excavator for install R.C pipe culvert Checking for location of pipe follow indicated inthe shop drawing or as directed by the Engineer

 The contractor shall lay reinforced concrete pipes carefully The hubs or grooved ends shall be upgrade The spigots or tongued ends shall be fully entered into the adjacent hub or groove and be true tothe required lines and grades

 Before laying succeeding sections of reinforced concrete pipe which do not required cambering, theContractor shall plaster the lower half of the hub of the preceding sections on the inside with Cementmortar The mortar shall be sufficiently thick to bring the inner surface of the abutting pipes flush andeven The Contractor shall plaster the upper half of the spigot of the succeeding pipe with the mortar atthe same time

 After laying reinforced concrete pipes, the Contractor shall fill the remainder of the joint withsufficient mortar to form a bead around the joint The Contractor shall wipe the inside of the joint andfinish it to a smooth and even surface The mortar on the outside shall be cured and remain damp fortwo days or until the Engineer allows backfilling to proceed

g) Completed surrounding concrete of pipe culvert

 After completed installation of pipe culvert, the contractor continue construction of remaining part ofSurrounding concrete

 Determined limit of boundaries of surrounding concrete indicated in shop drawing by stakes. Completed Surrounding concrete shall be inspected and approved by the Engineer prior to

constructing backfill layer

h) Backfill and compaction

 Backfilling shall be carried out with material approved by the Engineer placed in uniform layers notexceeding 100 mm in un compacted depth and thoroughly compacted Each layer of backfill material,if dry, shall be wetted uniformly to a moisture content approved by the Engineer to obtain a density ofnot less than 90% of that determined by AASHTO T180 or such other density as shall be directed onthe Drawings or by the Engineer

 Special care shall be taken to compact thoroughly the material under the haunches of the pipe, and toensure that the backfill shall be brought up evenly on both sides of the pipe for the full required length.Heavy earth moving and compacting equipment shall not operate closer to the culvert than 1.5 metresuntil covered to a depth equal to at least one fourth of the diameter of the culvert, but in no case lessthan 600 mm, unless otherwise approved by the Engineer Light weight equipment may be operatedwithin the above limitation after embankment has been placed and compacted to give a minimumcover of 300 mm over the top of the culvert

 Implement backfill both sides of pipe culvert at the same time and inspection density for each layerfrom below to above

i) Cleaning culvert

 The Contractor shall clean all culverts until they free of loose debris, soil and all foreign material TheContractor shall keep the culvert clean and maintain them in an operating condition throughout the

Contract period The Contractor shall only permit water to flow through the cleaned culvert after theEngineer inspected and approved the culvert.

j) Culvert headwalls, inlets and outlets

 Unless otherwise shown on the drawing, the Contractor shall construct all culvert aprons, wing walls,and headwalls using reinforced concrete of the class indicated in the drawing and in accordance withrequirements and provisions of Teachnical Specification

VII.QUALITY CONTROL

 QC Engineer shall inspect all work to ensure compliance to the requirement of Specification andDrawings

 Quality control flow chart:

After finish work

Inspect by site engineer

Inspect by QC manager

Inspect by Engineer:

Next workStrictly control of materials according to specifications and construction equipment.“Quality control plan” shall be submitted separately and shall be a part of this method statement

“Safety Control Plan” shall be submitted separately and shall be part of this method statement Priorand during the execution of the Road Earthworks, basic safety precautions shall be implemented towork efficiently and to prevent any accident or casualty

IX.ENVIRONMENT CONTROL

The Contractor shall be responsible for implementing and managing mitigation measures during theconstruction of the Works The recommended mitigation measures are presented below

1 Ambient air quality