Method statement of Underground Water Tank

CÔNG TY CỔ PHẦN XÂY LẮP THƯƠNG MẠI 2
Architects & Construction Service Corporation

METHODSTATEMENT
SMC Manufacturing (Vietnam) Factory-Phase 1 Project

SUB BUILDING 1- UNDERGROUND WATER
TANKS

Ref No:
SMC-ACS-MS-22A-CCW-001 Rev 00

ACSC- CONG TY CO PHAN XAY LAP THUONG MAI 2

SC-MS- Sub-building 1/Underground Water Tanks,.

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Revision History
Revision
00

Date of issue
31-Jan-2016

Purpose of issue (approved/ revision)
For Approval

Submitted by ACSC
Prepared by
Reviewed by
Approved by

Name
Le Long Hau
Nguyen Hoang Trinh
Nguyen Van Trung

Position
Deputy Site Manager
Site Manager
Project Manager

Date

Signature

Approved by KOA
Checked by
QA-QC
QA-QC
HSE
KDA

Position

Date

Signature

Date

Signature

Reviewed by
Approved by

Approved by Client Name
Prepared by
Reviewed by

SC-MS- Sub-building 1/Underground Water Tanks,.

Position

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Architects & Construction Service Corporation

Contents

1. INTRODUCTION
1.1. PURPOSE
The purpose of this Method Statement is to set up a policy for construction procedures and quality
according to Contract Specifications. Besides, it’s also outline the work instruction by which subbuilding 1 (including underground water tank, trench line and cooling water tank) by mentioning

typical structures such as bottom slab, wall and top slab of tank.

1.2. DEFINITIONS:
PROJECT PARTICULARS:
Project name

: SMC MANUFACTURING (VIET NAM) FACTORY-PHASE 1 PROJECT

Address

: Long Duc Industrial Park, Long Duc Ward, Long Thanh District, Dong Nai Province,
Viet Nam.

PARTY:
Client/ Owner : SMC MANUFACTURING VIETNAM CO., LTD
Contractor

: KAJIMA OVERSEAS ASEA PTE LTD.
Responsible for the supervision of Contractors who will construct the podium and all
related activities as outlined in this procedure.

SCOPE OF WORK
The works to be carried out by Sub-Contractor (ACSC) and shall apply for works at Factory No.9 of
SMC MANUFACTURING (VIET NAM) FACTORY-PHASE 1 PROJECT.
1. Construction Reinforcement Concrete Structure works included:
a. Pile head treatment
b. Earth work
c. Formwork
d. Reinforcement Steel Rebar work.
e. Concrete work

2. Finishing works included:
a. Brick work.
b. Plaster work.
c. Painting work.
d. Tiling work (Wall & Floor).
3. Sub-building included:
a. Underground water tank, trench line, cooling water tank.
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2. BUILDING DESCRIPTION:
Location:
Underground Water Tank is located under Sub building No.1, next to Factory No.9 at the corner of Road
No.D5 &N2-5 in Long Duc Industrial park as below

Sub Building No.1

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Sub Building No.1

54000

A1

D
B
22A-AR-201

500

6500

3000

1/20

EL+42.70

1/20

3000

EL+42.55

B
AW
1

AW
1

SD
1

AW
1

SS
1

AW
1

SD
1

AW
1

AW
1

SD
1

AW
1

SS
1

AW
1

SD
1

Ø

10000

EL+42.55

10000

EL+42.55

A
22A-AR-201

AW
1

AW
1

AW
1

AW
1

AW
1

AW
1

A
22A -A R-201

LSD
1

AW
1

AW
1

AW
1

AW
1

AW
1

AW
1

A

8500

EL+42.55
10000

10000

10000

10000

10000

10000

60000

1

2

B
22A-AR-201

3

4

5

6

7

3700~4200

3700~4200

E

? GFL±0

?

?

3500

2800

150

42.55

150

? GFL±0

10000

10000

10000

10000

10000

10000

60000

1

2

3

4

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5

6

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7

42.55


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Underground water treatment tank
+ Dimension
: L x W x H : 10 x 10 x 4.1 (m)
+ Structure
: Reinforced concrete

RC Concrete Volume (m3):
Structure

Dimension (m)
Length
10.4
10.4
10.4

Bottom slab
Walls
Cover slab

Wide
10.4
0.3
10.4

Concrete
Volume (m3)
Height
0.35
3.5
0.25

37.86
43.68
27.04

3. ORGANIZATION CHART
3.1. Organization Chart

Project Manager
NGUYỄN VĂN TRUNG (MP: 090 330 7742)


Site Manager
NGUYỄN HOÀNG TRINH (MP: 090 291 1235)


Deputy Site Manager

Deputy Site Manager

NGUYỄN TRÍ KHOA (MP: 093 722 9680)

LÊ LONG HẬU (MP: 093 232 5944)





Site Engineer

QC engineer

NGUYỄN MINH TUẤN (MP: 098 314 5069)
SC-MS- Sub-building 1/Underground Water Tanks,.
NGUYỄN VĂN HÀO (MP: 093 872 2730)

PHAN QUỐC TRƯỜNG (MP: 098 314 5069)
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Safety Supervisor

Shop Drawing

ĐỖ VŨ QUYỀN ANH (MP: 090 853 1908)

HOÀNG VĂN HẢI (MP: 0122 761 2260)


Construction Team
PHƯƠNG PHƯƠNG VIỆT COMPANY

3.2 Assignment
Position
Deputy Site manager
Site Engineer
QA&QC Engineer
Safety Supervision

Factory No.1
NGUYỄN TRÍ KHOA

Factory No.9
TRẦN AN TOÀN

NGUYỄN MINH TUẤN
NGUYỄN VĂN HÀO
PHAN QUỐC TRƯỜNG
ĐỖ VŨ QUYỀN ANH

LÊ VĂN TUẤT
BÙI CÔNG HUYNH
NGUYỄN ANH ĐỨC

PHẠM VĂN MẠNH

4. FLOW CHART AND DIRECTION OF WORK
The sequence of construction is shown at the following flowchart.
Excavation foundation
Lean concrete
RC Bottom slab
RC Walls

Formwork installation
Steel rebar installation
Casting concrete

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Backfilling excavation

Formwork installation
Steel rebar installation
Casting concrete

RC Cover slab

Removal of formwork

Waterproofing work

5. SCHEDULE
Construction Schedule of water tanks is attached in Appendix-2.

6. SPECIFIC STANDARD
Reinforced Concrete Footings shall be carried out in accordance with the requirements of:
-

SMC MANUFACTURING (VIET NAM) FACTORY-PHASE 1 PROJECT Specification for Footing works.
Current Vietnamese Construction Standards.
+ TCVN 4447-2012 Vietnamese standard 4447-2012 (Earth works - construction, check and
acceptance)
+ TCVN 5593 : 1991 Vietnamese standard 5593-1991 (Building engineering work - Permissible
tolerances in geometry)
+ TCVN 1651-2008 Vietnamese standard 1651-2008 (Steel for the reinforcement concrete,
part1+2)

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-

+ TCVN 4453 – 1995 Vietnamese standard 4453-1995 (Concrete structures- codes for

construction, check and acceptance)
+ TCXDVN 371 - 2006Vietnamese standard 371-2006 (Acceptance of constructional quality of
building works).
Related Materials approved by KAJIMA & Owner.

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7. TOOL & EQUIPMENT
The equipment to be used for the construction of Footings is listed below.
Description

Unit

Q’t
y

Dump Truck

10 tons capacity

Nos.

1

Transport the excavated soil

Backhoe

L= 4.5m, 0.70m3
capacity

ea.

1

Excavation and backfill

Submersible Pump

4 inches, H=24m
minimum

Nos.

1

Stand by pump for dewatering

Rammer

Nos

2

Compacting backfilled soil

Plate compactor

Nos

1

Compacting for lean concrete

Nos

4

Vibrate concrete

Concrete cutter

Nos.

2

Use for cutting surplus pile head

Portable steel cutter

Nos

2

Use for cutting steel bar

Straightening machine

Nos

1

Use for reinforcing steel work
Diameter <8mm

Cutting machine

Nos

1

Use for reinforcing steel work

Welding machine

Nos

4

Use for reinforcing formwork

Bending machine

Nos

1

Use for reinforcing steel work

Hack-sawing machine

Nos

2

Manufacturing formwork

Screwdriver /Drilling machine

Nos

4

Manufacturing formwork

Level machine

Nos

1

Control the elevation

Theodolite

Nos

1

Locate the gridline

Item

Concrete Vibrator

Gasoline

8. MATERIALS
a/ Concrete: ready mixed concrete (supplied by KOA)
-

For Lean concrete: grade B10
For structure: grade B20

b/ Steel rebar: (supplied by KOA)
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Remarks


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-

With Diameter < 10mm: SR295
With Diameter >10mm : SD390, B15-B35

c/ Formwork:
-

Plywood, 18mm thickness. reinforced with steel boxes 40x80x1.8 (mm)

9. MATERIALS HANDLING, STORAGE AND DELIVERY
-

Concrete: Ready- mixed concretes are transported from batching plant to site in concrete truck (6
to 12 m3 capacity). The concrete must be delivered to site within maximum 60 minutes depend
on the mix design of concrete supplier.

-

Formwork: Formwork will be pre-fabricated then stocked on yard with protection of plastic
cover. Before installing, the formwork will be transported to site and placed near the excavation.
The surface of formwork must be clean of dirt, loose concrete and to be applied the release
agent, if needed.

-

Steel rebar:
Delivered reinforcement bars are to be stored in stockyard nearby fabrication shop for
convenient moving to the shop for cutting and bending.
Fabricated bars will be separately stored in the next area in the fabrication yard with tagged

bundles to avoiding steel scraps mix-up.
Steel bars are stored on the steel platform or concrete blocks to prevent the contact of steel
rebar with the ground. All steel rebar are stocked in the steel yard with roofing and cover with
plastic sheet to protect them with rain water.
Unloading reinforcement from trailer will be carried out by a suitable crane for lifting up
reinforcement bundles.
Prior to fabrication of reinforcement, samples shall be taken from each batch of each size of
each delivery and tested for compliance in accordance with Quality Control procedures.

-

Other materials are keeping in storage and they are transported to the site work when they are
in used.

10. PREPARATION WORKS
-

Excavation foundation
+ Receiving the construction area transited by KOA.
+ Receiving the coordinate, benchmark system from main Contractor (KOA).
+ Clearing the ground and remove any obstruction on the ground.
+ Set up drainage system for rainwater and underground water inside and outside pit
+ Prepare internal road from the excavation to the stock yard of surplus soil.
+ Setting out excavations with their center lines, dimension and marking on the ground.

-

Casting lean concrete
+ Completing the excavation above design level about 100mm high.
+ Drainage and pump water regularly, keep the pit dry.

+ Trimming the surplus soil by hand to the design elevation.
+ Compacting the base of foundation and testing, if required.

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-

Installation of form work
+ Completing lean concrete
+ Setting out and marking the gridlines and dimensions of footings on lean concrete surface.
+ Pre-fabricate formwork
+ Cleaning and applying release agent on formwork surface, if required.

-

Installation of rebar
+ Shape and dimension of rebar.
+ Machine for fabricate rebar.
+ Obtaining the approved Shop drawings.

-

Casting concrete
+ Inspecting of rebar and formwork (record, pictures).
+ Prepare internal road for delivery concrete

+ Cleaning formwork, lean concrete's surface, pump water out of pit.
+ Check finishing level of concrete
+ Covered starter rebar by PVC sheet before casting.
+ Prepare bucket or slide for casting from top to bottom.
+ Order the concrete.

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11. CONSTRUCTION METHOD
11.1. Excavation
•

Step 1: Survey and mark the foundation boundary on the ground included: Hand over &
Take over Coordinate markers, Level markers, Gridlines, Survey Point & Temporary
Benchmarks. Set up Perimeter of area to be excavated and temporary access to
excavations.

•

Step 2: Excavate the soil: Using backhoe machines (0.7 m3) to excavate the soil. Excavate
with backhoe to the level 100mm higher than the design levels. The slope of excavation is
generally 75o. The dimensions of excavation generally ≥ 500mm wider on each side of
footing for worker operation and installation of formwork.

•

Step 3: The remaining soil will be trimmed by hand to the design level.

•

Step 4: Transportation and disposal surplus soil to designated location.

a. Stocked soil:
Surplus soil will be transported to the soil reservation location on the site designated by KOA.
For the back filling process, the soil is gathered as masses which less than 1.5m height and
more than 1.5m distance far from the edge of opening hole. It is temporary covered by
canvas to prevent the dust and used for back filling process later.

The volume of soil stocked on construction area (for backfilling) are based on the excavated soil
subtract the volume of casting concrete. The volume of excavating soil, casting concrete are shown in
table below:

Excavated Soil volume (m3)
No.

Excavation
Waste water tank

SC-MS- Sub-building 1/Underground Water Tanks,.

Level
-4.35m

Page 13

Q’ty
1

Volume
60,41x13,27

Total (m3)
801,64


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The surplus soil will be transported by truck to the stock yard (≈2000 m2) designated by KOA.
Remaining soil will be leveled at height of 0.5m from existing ground level.

ACSC Soil stock area

b. De-watering excavation:
Because of construction in dry season, the dewatering work is not critical. However a standby pump
will be prepared.

11.2. Lean concrete.
•
•
•

Step 1: Trimming the soil: This work is carried out by digging by hand to form an even and
firm base at the right bottom levels of foundation.

Step 2: Using the rammer and plate compactor to compact the soil to get the level K >=
0.95
Step 3: Using steel box 40x80 (mm) to manufacture the form work for foundation lean
concrete layer. The dimensions of lean concrete will be 100mm wider on each side to
facilitate the installation of formwork later.

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•

11.3.

Step 4: Casting lean concrete grade B10, stone 1x2 with ready-mixed concrete from the
concrete truck via the chute. Finishing the concrete surface using straight bar and level
machine.

Formwork of bottom slab
•
•
•
•
•
•

Step 1: Setting out the gridline and perimeter of foundation on the surface of lean
concrete using theodolite machine.
Step 2: Install the pre-fabricated formwork at the locations and dimensions, which are
marked before.
Step 3: Fix the bottom of formwork with steel box, nails.
Step 4: Adjust the formwork to be plumb and straight with steel propping and adjusting
jack.
Step 5: Fix the corners of formwork with nails and secure the formwork with adjusting
jack against the stake on ground.
Step 6: Fill any gap of formwork with lean concrete with mortar.

ELEVATION OF WASTE WATER TANK
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LAYOUT OF FONDATION FORMWORK

11.4.

Steel work of bottom slab
•
•
•
•
•

•

Step 1: Cleaning rebar surface.
Step 2: Fabricate the steel rebar by cutting, bending in compliance with approved shop
drawings. Tagging the steel rebar.
Step 3: Transport the fabricated steel rebar to site.
Step 4: Marking the positions of rebars on lean concrete surface and place the rebars in
sequence bottom first and then top. Position for lap and lap length as direction
Step 5: Tie the steel rebar strongly with wire in correct positions and distance. For water
bar, we also carry out same way.
Step 6: Insert spacer under and outside of steel cage to form the concrete cover.
Spacers will be pre-made with fine aggregate concrete, grade B20. They are shaped by
casting in PVC mould D42- D49 (mm). Their heights are depended on the thickness of
concrete cover determined in Technical Specification for each kind of structures. The
concrete proportion is proposed for one mix as below:
Cement

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: 50 kg
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Sand
: 49 liter
Fine stone (dmax=10mm) : 99 liter
Water
: 22.8 liter

11.5.

Concrete work of bottom slab
•
•
•

•
•
•

Step 1: Delivered ready-mixed concrete will be checked of slump as regulation, slump for
foundation should be 8÷10 cm.
Step 2: Concrete will be poured to formwork with chute or concrete pump, depend on
the distance from the concrete truck to the footings.
Step 3: Casting concrete should be performed outside to inside, around edge, then
coming center. Using vibrator for compaction of concrete. Duration of each vibration is
not less than 10 second.
Step 4: Check the finished top level of concrete surface and remove surplus concrete.
Step 5: Finishing the concrete surface with troweling.
Step 6: Curing concrete. After 12 hours casting concrete, the surface of RC footing is
covered by a hessian. Spraying water at least 2 times per day (sunny day). Curing
concrete is not less than 05 days

CURING CONCRETE FOR BOTTOM SLAB

11.6.

Formwork of walls

•
•

•
•

Step 1: the procedure of installing show in picture below. Wall formwork and column
formwork will install at the same time.
Step 2: Install the pre-fabricated formwork at the locations and dimensions, which are
marked before. Normally, install outside wall first, then install wall rebar completely.
Finally, install the inside wall formwork.
Step 3: Fix the bottom of formwork with steel box, nails. The formwork of columns and
wall will be braced with the tie rods D10 as illustrated.
Step 4: Adjust the formwork to be plumb and straight with steel propping and adjusting
jack.

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•
•

11.7.

Step 5: Fix the corners of formwork with nails and secure the formwork with adjusting
jack against the stake on ground.

Step 6: Fill any gap of formwork with sealant.

Steel work of walls
•
•
•
•
•
•

Step 1: Cleaning rebar surface.
Step 2: Fabricate the steel rebar by cutting, bending in compliance with approved shop
drawings. Tagging the steel rebar.
Step 3: Transport the fabricated steel rebar to site after installing outside formwork
completely.
Step 4: Marking the positions of rebars on lean concrete surface and place the rebars in
sequence bottom first and then top. Position for lap and lap length as direction
Step 5: Tie the steel rebar strongly with wire in correct positions and distance. For water
bar, we also modify position and then fix into rebar by wire.
Step 6: Place the spacers on both side of formwork, spacing 1m for vertical and
horizontal direction.

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11.8.

Concrete work for wall and column
•
•
•
•
•
•
•

Step 1: Delivered ready-mixed concrete will be checked of slump test. Slump of concrete
for wall/column should be 12±1 (cm).
Step 2: Concrete will be poured to formwork with chute or concrete pump, depend on
the distance from the concrete truck to the footings.
Step 3: Casting concrete should be separated layer by layer, with thickness less than
0.5m.
Step 3: Using vibrator for compaction of concrete. Duration of each vibration is not less
than 10 second.
Step 4: Check top level of wall concrete while casting and remove surplus concrete.
Step 5: Finishing the concrete surface with troweling.
Step 6: Curing concrete. Spraying water at least 2 times per day (sunny day). Curing
concrete is not less than 05 days.

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CURING CONCRETE FOR TANK WALL

11.9.

Formwork of cover slab
•
•
•
•
•

11.10.

Step 1: Install scaffolding, steel tube Ø49, steel box 40x80mm… as illustrated below
Step 2: Install the pre-fabricated formwork at the locations and dimensions, which are
marked before.
Step 3: Re-check level of formwork before casting, each 4m 2/ point
Step 4: Modify base/top jacks to get required level before casting.
Step 5: Fill any gap of formwork with tape.

Steel work of cover slab
•
•
•

Step 1: Cleaning rebar surface, chipping surplus concrete of wall.
Step 2: Fabricate the steel rebar by cutting, bending in compliance with approved shop
drawings. Tagging the steel rebar.

Step 3: Transport the fabricated steel rebar to site after installing formwork completely.

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•
•
•

Step 4: Marking the positions of rebars on formwork surface and place the rebars in
sequence bottom to top. Note lap length and reinforce around opening as spec.drawing.
Step 5: Tie the steel rebar securely with wire in correct positions and distance.
Step 6: Insert the spacer on slab formwork, spacing 0.6x0.6 (m).

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11.11. Concrete work of top slab
•
•
•

•
•
•
•

Step 1: Prepare concrete slump, concrete grade similar bottom slab.
Step 2: Concrete will be poured to formwork with chute or concrete pump, depend on
the distance from the concrete truck to top slab.
Step 3: Casting concrete should be performed outside to inside, around edge, then
coming center.
Step 3: Using vibrator for compaction of concrete. Duration of each vibration is not less
than 10 second.
Step 4: Check the finished top level of concrete surface and remove surplus concrete.
Step 5: Finishing the concrete surface with troweling.
Step 6: Curing concrete. After 12 hours casting concrete, the surface of RC slab is covered
by a hessian. Spraying water at least 2 times per day (sunny day). Curing concrete is not
less than 05 days

11.12. Back filling
+ Marking the height on tank wall. The thickness of each layer should not exceed 0.5m/ layer.
+ Backfill the excavation with excavated soil, using excavator, workers and rammer.
+ Spray water before compacting.
+ Compacting the soil using rammer to reach the designed compaction K≥ 0.95.
+ The testing will be carried out for each 300 m2 of each layer.
+ Repeat the backfill and compaction until reach to the finished level.

12. QUALITY CONTROL
With regards to the quality control, all works shall be carried out following the established Project
Quality Control Plan. Method to treat mistake or defect during constructing:

-

Excavation:
+ Locate position of project by survey machine.
+ Determine the level of bottom slab by leveling machine

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+ Check dimension of pit by tape.
+ Tolerance for border, center line, dimension of pit: ± 50mm.

-

Lean concrete:
+ Check the surface by survey machine, tolerance ±1cm

-

Installation of form work
+ Check by leveling machine, tape: Axis tolerance ±8mm; Tolerance for the whole foundation
height ±20mm
+ Check tightness of formwork by visual.
+ Check rigidity and stability of bracing.

-

Installation of rebar
+ Checking material: certificate, check dimension by caliper,take the sample for checking
physical-mechanical.
+ Check the length, number, position, anchor length, joint by visual and ruler.
+ Thickness of protection: checking by tape
+ Tolerance for installation: Spacing among main rebars:20mm, Stirrups spacing: 10mm.
+ Tolerance for protection layer: Foundation: 10mm.
+ Tolerance for fabrication: the whole length: 20mm, bending: 20mm
+ Lap length: Rebar SD390 Ribbed bar: 40d(tensile), 15d(compressive)

-

Casting concrete
+ Level tolerance on surface: 20mm.
+ Horizontal tolerance of section:± 8mm.
Back filling
+ Inspect each layer after compacting.
+ Testing compaction factor as technical requirements and method of owner.

-

13. RISK ASSESSMENT
See attached Appendix No.4

14. SAFETY PLAN
With regard to health and safety control, all the works shall be carried out following KOA Safety
regulations. Some of safety measures are shown as below:
No.

Description of job

Hazards

Hazard events
Injury or death to
workers or
operators

+Traffic accident
during
mobilization/dem
obilization
1

Excavation works

+ Accident during
excavation
and
transportation
the soil.

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Preventive measures
+ Security standby and control
public

traffic.
Mobilization/demobilization
should not carry out during
heavy traffic jam (morning
time/evening time)
+ Excavator should observe
roads speed limits.
+ Follow strictly the method
to prevent the landslide.
Heavy objects must stand by
at least 1.5m from the edge of
opening excavation.

Action by
Forman /
Supervisor /
Worker


CÔNG TY CỔ PHẦN XÂY LẮP THƯƠNG MẠI 2
Architects & Construction Service Corporation
+Apply the barrier, ribbon &
signboard to prevent the
workers fall down to the pit.
+ Excavator driver must has
license, excavator must be
verify certificate and good
active status.

+ The soil around

of foundation can
be slide.

2

3

4

5

6

Form and Re-bar
Installation and
Concreting Works

Removal or
dismantling forms
or any temporary
structures
Backfilling works

Unsanitary Site
Condition

Machinery & Other
Equipment

Fall down of

concrete
equipment
accessories
worker hit by
these falling
objects

Injury of
people/worker

Workers struck or
hit by falling fill
materials or any
objects.
Workers struck or
hit by falling fill
materials or
equipment

Injury of
people/worker

Scattering of
dirt/garbage and
some chemicals

Oil spillage to
earth

Injury of

people/worker

Damage to
neighborhood
inhabitants

Damage to
neighborhood
inhabitants

Safety check sheet is attached in Appendix No.5

15. APPENDIX
Appendix-1: Working Drawing
Appendix-2: Construction Schedule
Appendix 3: KOA’ ITP for related works
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+ Workers must alert when
installation of heavy steel
materials
and
during
welding works.
+ Wear protective equipment
during
installation and concreting
works.

+ Provide qualified personels
to do and supervise the job.
Provide proper equipment
platform and qualified
signal man for dump trucks
unloading backfill
materials.
+ Avoid leaking of chemicals
and other solution
+ Keep the site clean before
stop
working
+ To make sure all machinery
free of oil leak.
+ Repairing/maintenance of
machine and other equipment
should be done with proper
way to avoid oil spillage to
earth/ drain.

Forman /
Supervisor /
Worker

Forman /
Supervisor
Forman /
Supervisor

Forman /

Supervisor /
Worker

Forman /
Supervisor /
Worker


CÔNG TY CỔ PHẦN XÂY LẮP THƯƠNG MẠI 2
Architects & Construction Service Corporation
Appendix 4: Formwork calculation.
Appendix 5: Risk assessment
Appendix 5: Safety checksheet

END

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