METHOD STATEMENT FOR CW PIPE LINE CIVIL WORK

Comment Response Sheet (CRS)
Project Title

Van Phong 1 BOT Thermal Power Plant Project

Document Title

METHOD STATEMENT FOR CW PIPE LINE CIVIL
WORK

Document Type

For Approval

Document No

VP1-0-L4-C-UPF-10051

Returned Status

NA

Prepared by

CRS No

VP1-0-L4-C-UPF-10051-B-CRS

CRS Issued Date

1/06/2020

Engineer

Construction

Review
Date

Status O/C *

Remarks

15/05/2020

O

1/06/2020

C

15/05/2020

O

1/06/2020

C

15/05/2020

O

1/06/2020

C

No.

1

Section/
Page
2

Owner’s Comment

Response to Comment

15/05/2020
TCVN 4447:2012 shall be referenced

DHI has been updated

Lot 4

1/06/2020
Closed
2

3

15/05/2020
- Capacity of machine should be stated
- Pump for de-watering system shall be mobilized.

DHI has been updated

1/06/2020
Closed
However, further comment about the capacity of
pump is shown on page 3.
3

4

15/05/2020
QC will participate in which step of this sequence
for inspection?
By that, Lot4 can establish a proper ITP.

QC shall be follow ITP of General Excavation &
backfilling and General concrete work.

1/06/2020
Closed

Page 1 of 6


Comment Response Sheet (CRS)

4

6

15/05/2020
In case the worker will work at the bottom of
excavation (pipe adjusting, welding, compaction..)
the width shall be 700 for safety purpose, please
refer to TCVN 4447:2012
1/06/2020
OPEN
Applied standard shall be complied properly.

5

6

15/05/2020
De-watering system shall be mention and reflect
on section/layout

At the design stage, The excavation section had
been reviewed by Lot3. there is no issue about
working space for Civil & Mechanical work.

15/05/2020

O

1/06/2020

Closed
O

15/05/2020

O

1/06/2020

C

15/05/2020

O

1/06/2020

C

DHI revised as following comment & TCVN.

DHI has been updated

1/06/2020
Closed
6

6

15/05/2020
Specify the distance between the barricade and
dike to the edge of the excavation. The slope is
very steep and the excavation is almost 6m deep.
A surcharge too close to the edge could lead to
failure. The dike also needs to be at a sufficient
distance so that any minor local slope damage
does not compromise the dike and lead to
additional erosion damage.

The distance between the barricade and dike to
the edge of the excavation is 2m. DHI revised.

1/06/2020
Closed

Page 2 of 6


Comment Response Sheet (CRS)
7

6

15/05/2020
- With a deep excavation, any slope protection will
be provide? slope stability check for 1:0.5 will be
provided?
- To insert the reference soil boring log to cross
section of each zone or different soil condition.

1/06/2020
OPEN
- How to evaluate it is enough ratio for slope? CW
pipeline is very long and soil condition change
along Zone 2,3,4,5,6. Mean each zone may have
a different typical section.
- To insert the reference soil boring log to cross of
each zone or diff. soil condition

8

14

15/05/2020
Present a typical access way and its arrangement

1:0.5 is enough ratio for temporary slope in
consideration of ground condition at site.

15/05/2020

O

1/06/2020

O
Closed

15/05/2020

O

1/06/2020

C

15/05/2020

O

1/06/2020

C

DHI added the Soil Investigation Report to
reference list.

Slope stability for 1:0.5 had been checked as
attachment2. The result is safe.
if there is any concern of soil condition during
excavation time, DHI can make more slope,
maximum 1:1

DHI has been updated

1/06/2020
Closed
9

17

15/05/2020
Excavation pit for welding work of CW pipe shall
be mentioned?
Is there any interface with Lot3?

The excavation section had been reviewed by
Lot3. There is no issue about working space."
Mechanical work and the related will be fulfilled
by Lot3

1/06/2020
Noted
And will review in the method statement of pipe
erection from Lot3.

Page 3 of 6


Comment Response Sheet (CRS)
10

22

15/05/2020
It is totally unacceptable, this task contain a lot of
potential critical hazards. Moreover, risk
assessment is a kind of anticipated document and
preparing based on each kind of method
statement. EPC to prepare risk assessment for

this task and pertaining to this method statement
as it is integral part for the submission and site
implementation.

DHI has been updated

15/05/2020
1/06/2020

O

OPEN O
Please refer to section 8.1 for
detail comment

1/06/2020
OPEN
Please refer to section. 8.1 for detail comment.

Page 4 of 6


Comment Response Sheet (CRS)
11

Cover

1/06/2020
(1) Pls update the underground water level into
the drawing sections.

(2) Item 6.2- Sand bedding: Noted excavated soil
is not suitable for all. Pls re-check and confirm.
AND compaction required layer by layer should be
K95.

1/06/2020

O

1/06/2020

Closed
O

(1)UG water level in Soil Investigation Report is
meaningless for now cause the site condition has
been changed by site development work.(some
UG water level in SI report is indicating EL.+10 or
9). So we cannot figure out exact UG water level
before excavation. Or we can assume UG water
level EL.+0.07 same as BH-42 which the
elevation had not been changed remarkably.
(2)The mention was mistake. DHI deleted.
Sand bedding will be tested for 95%.
Backfilling will be fulfilled layer by layer with
mentioned % in design drawing.
(3)

(3) Show protection of steel pipe at anchor contact

pipe perimeter. Please ensure no pipe uplift at any
cases during construction.

12

3

1/06/2020
Pump capacity ~20m3/h?
It is seem not okay with an area of 150m x 16m?

1. DHI will use soft material (ex. Sand in site)
around manhole of CW pipe.
2. DHI had discussed with CTCI. they will not
block end of pipe during installation to prevent
pipe floating. In addition, DHI make dike around
excavation area to block ground water flowing
into excavated area. (in case CTCI install sand
bag at the end of pipe, the height must be
checked to prevent effective buoyancy.)

DHI revised. 2 pumps can cover the area for rain
100mm/hour.

Page 5 of 6


Comment Response Sheet (CRS)
1/06/2020
1. Please provide the identification and propose

the countermeasure for step of sand bedding
mentioned in this method statement.
2. Based on Doosan's risk assessment procedure
the JSEAs for identified tasks be prepared in for
steps identified through the risk assessment
process as having a Residual Risk Number
greater than 6. Please supplement the missing
JSEAs for the review and site implementation.
Additional Notes (if any)
* O - Open, C – Closed
13

24

1.DHI has been updated
2.JSA is basically same except the capital “E”
(environment).And the submitted JSA is covering
environment too.

1/06/2020

OPEN
PleaseOrefer to section 8.1 for
detail comment

Page 6 of 6


AP

APPROVED
Approved

AC

APPROVED WITH COMMENT
Contractor to revise the correction and resubmit

NA

NOT APPROVED
Revise the correction and resubmit before proceeding

RE

REVIEWED
Information acknowledged with no comment
For Approval

RC

REVIEWED WITH COMMENT
Information acknowledged with comments

Note: Approval or comment does not relieve the Contractor of
all obligations covered under contract

Discipline: Civil
16 Jun 20
Date:

C

5-Jun-2020

For Approval

J.H CHOI

K.S KIM

D.H JEONG

B

21-May-2020

For Approval

J.H CHOI

K.S KIM

D.H JEONG

A

08-May-2020

For Approval

J.H CHOI

K.S KIM

D.H JEONG

REV

DATE

DESCRIPTION

Approved

Checked

Prepared

OWNER

VAN PHONG POWER COMPANY LIMITED
PROJECT

Van Phong 1 BOT Thermal Power Plant Project
Status
□Approved
□Approved with Comment
□Not Approved
□Reviewed

OWNER’S ENGINEER
Pöyry Switzerland Ltd.
EPC CONTRACTORS

IHI–TESSC–CTCI–DHI CONSORTIUM

PROJECT DOCUMENT No

REV

VP1-0-L4-C-UPF-10051

C

DOCUMENT TITLE

METHOD STATEMENT FOR CW PIPE LINE CIVIL WORK
EPC

EPC DOCUMENT No.
VP1-0-L4-C-UPF-10051

Doosan Heavy Industries and Construction
Page | 0

REV
C

VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

Table of Contents
1. PREFACE ...........................................................................................................................- 2 2. REFERENCE .......................................................................................................................- 2 2.1 Applicable Code and Standard ............................................................................................................. - 2 2.2 Drawing and Method Statement.......................................................................................................... - 2 -

3. MANPOWER & EQUIPMENT ........................................................................................- 2 4. RESPONSIBILITIES AND ORGANIZATION .................................................................- 3 5. PROCEDURE AND SEQUENCE ......................................................................................- 4 6. CONSTRUCTION WORK ................................................................................................- 6 6.1

Excavation ................................................................................................................................................. - 6 -

6.2

Sand bedding .......................................................................................................................................- 17 -

6.3

Backfilling ................................................................................................................................................- 18 -

6.4

Concrete Encasement ........................................................................................................................- 21 -

7. INSPECTION AND TESTING ....................................................................................... - 22 8. ENVIRONMENT, HEALTH AND SAFETY (EHS) ....................................................... - 23 8.1 Risk Assessment ......................................................................................................................................- 23 8.2 Job Safety Analysis ................................................................................................................................- 49 -

9. ATTACHMENT……………………………………………………………………………- 49-

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

1.

PREFACE
The purpose of this method is to describe the methodology involved in construction work for the
CW Pipe line item and to detail out the steps to be taken in order to meet the technical
requirements of VP1 BOT Thermal Power Plant.

2.

 Project

Van Phong 1 BOT Thermal Power Plant

 Company/Owner

Van Phong Power company limited(VPCL)

 Contractor

DHI

 ITEM

CW Pipe Line

REFERENCE
2.1 Applicable Code and Standard
• Part III-2 Exhibit B1 Tech Spec Section 8.
• Part III-2 Exhibit B1 Appendix G Civil/Structure Technical Guideline.
• TCVN 4447-2012 Earth works – Construction, check and acceptance

2.2 Drawing and Method Statement

3.

•

VP1-0-L4-C-GEN-10007_ Rev C_ Method statement for General concrete work.

•

VP1-0-L4-C-GEN-10008_ Rev B_ Method statement for Excavation and backfilling work.

•

VP1-0-L4-C-UPF-12101_ Rev B_ CW Supply & Discharge Pipe Line Overall Plan Drawing

•

VP1-0-L4-C-UPF-12102_ Rev B_ CW Supply & Discharge Pipe Line Plan and Section Drawing.

•

VP1-0-L4-C-GEN-00001_Rev H_ Soil Investigation Report

MANPOWER & EQUIPMENT
• Manpower mobilized for construction of the Boiler are listed as followings:
No.

Position

Quantity

1

Site Manager

01

2

Site engineer

04

3

Safety supervisor

01

4

Surveyor

02

5

Excavator operator

03

6

Roller operator

03

7

Worker

60

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

• Equipment mobilized for construction of the Boiler are listed as followings:
No.

C

Equipment

Unit

Quantity

Capacity

1

Total station

nos

02

-

2

Auto level

nos

02

-

3

Dump truck

nos

10

8-18m3

4

Excavator

nos

03

0.7-1.5m3

5

Roller

nos

02

14ton

6

Rammer

nos

02

0.7ton

7

Plate compactor

nos

02

8

Light

nos

20

9

Electric Pump

nos

15

400W
11HP120m3/h

4. RESPONSIBILITIES and ORGANIZATION
• It is overall responsibility of Site Manager to organize resources prior to perform construction
activities as per project specification in compliance with the quality, schedule & safety requirements.
• EHS Manager will ensure in coordination with Site Engineer that all measure/construction taken shall
be maintained till completion of job.
• It is the responsibility of Construction Manager/Site Engineer that construction activities are executed
according to the relevant project specification in compliance with the quality, schedule & safety
requirements.
• Contractor will ensure that all works are performed safely according to the attachment.
• The relevant contractor Supervisor will ensure that the work is carried out in accordance with this
method statement and project specification.
• The QC Inspector will ensure that the work is executed according to the requirements of quality
dossier are fulfilled.

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

5. PROCEDURE AND SEQUENCE

- 4 - | Page


VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

SEQUENCE: Divide CW Pipe line to 6 Zone, Direction of executing from north side to south side, Zone 1
to Zone 6

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

6. CONSTRUCTION WORK
•

Reference Method statement: “VP1-0-L4-C-GEN-10008_ Rev B_ Method statement for Excavation
and backfilling work” for requirement and describe of Excavation, backfilling and concrete work.

•

This method statement mention for Procedure and Sequence for CW Pipe line only.

6.1 Excavation
•

Before start excavate work, Dike and hard barricade system at Ground level surround pipe line
shall be made. Ratio of slope: 1H:0.5V. The distance between the barricade and dike to the edge
of the excavation is 2m.

•

Width of the trench shall not be less than the outer diameter of the pipe addition 500 mm on
either side as following design drawing.

•

Soil will be cut by excavator crawler, transportation by dump truck.

•

Always arranging watchman for each excavator. The standing position of the watch man must
be appropriate and outside of the rotation of the excavator.

•

Regularly using auto level or/and total station surveys bottom of trench in compliance the design
drawing.

•

Sump pit for de-watering shall be arrange along in bottom of the trench. Use electrical pump
to pump water out. Sump pit and human access way arrange next to location of Encasement
and not greater than 150m.

•

If there is any concern of soil condition during excavation time, contractor can make more slope,
maximum 1:1.

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

Zone 1 Plan

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

Zone 2,3,4,5 Plan

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

Zone 6 Plan

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

Typical of section for human access way and sump pit for de-watering. Access way for equipment
will be arranged along the next excavation area on excavating period.

C

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

6.2 Sand bedding
• Before placement sand bedding, the trench shall be checked for big stones or any other objects which
may have on the trench after excavation. And shall be kept free from water too.
•

C

• Fill materials shall be laid, spread and leveled by bulldozer and compacted by roller compactor to the
required density. Maintain the moisture content of fill material usually +/- 2 percent on optimum
moisture. If required, add clean water by spray water truck or dry up to fill material in order to maintain
the optimum moisture content.
• Use Crawler excavator put sand material into bottom of trench.

C

• Levelling by bulldozer and worker shall be finishing in difficult area if necessary.

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VAN PHONG 1 BOT THERMAL POWER PLANT PROJECT

C

6.3 Backfilling
• The filling shall commence only after approval by Engineer-in-charge is obtained and after the
structures or pipes getting buried are approved.
• Filling area surface shall be kept free from water, such as materials and debris.
• Backfill material shall be selected material to the acceptance of the Engineer. It shall be free of roots,
stone or debris and checked for big stones or any other objects which may have on the trench after
installation piping.
• The material shall be carefully placed and packed around the pipes.
• Care must be exercised to protect, pipes, joints and other features from damage due to backfilling and
consolidation.
• After finishing the Pipe install
• Fill materials shall generally be placed in layers, and uniformly compacted to the satisfaction of the
Engineer by field density test before the next layer is applied. Loose thickness of each layer shall not

be greater than 300mm.
• Field density test (FDT), Material backfill shall be carried out according with ITP General Excavation and
Backfilling work.

C

• DHI had discussed with CTCI. CTCI will not block end of pipe during installation to prevent pipe floating.
In addition, DHI make dike around excavation area to block ground water flowing into excavated area.
• Make sure the pipe is open, if rain suddenly, water can flow in, and backfilling soil to ensure balance
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