MS 009 01 ECSI method statement

GENERALThis method statement describes the procedures for construction of the Existing Combined Sewer Improvement and Secondary Interceptor Sewer by open cut method including preparatory

M ETHOD S TATEMENT

MS-009-01

SHIMIZU CORPORATION

PACKAGE D CONVEYANCE SEWER CONSTRUCTION AND EXISTING COMBINED SEWER IMPROVEMENT

b) Each copy is issued to a particular person or organization If the

document is no longer required it should be returned to the relevant person;

c) It is not to be photocopied either in whole or in part Additional copies are available on request;

d) Copy holders will be automatically issued with any amendments

Responsibility for incorporating such amendments rests with the copy holder.

O CAMPO

TABLE OF CONTENTS (CONT’D)

APPENDICES:

1 GENERAL

This method statement describes the procedures for construction of the Existing Combined Sewer Improvement and Secondary Interceptor Sewer by open cut method including preparatory works, earthworks, pipe / box culvert installation and construction of the inlet pits / manholes / diversion chambers The Method Statements noted hereunder will be submitted under separate cover by the Contractor in compliance with the Specification and Conditions of Contract:

• MS-009-02 Design of Temporary Shoring for Excavation (01)

• MS-009-03 Design of Formwork (01)

• MS-010-01 Method Statement for Road Reinstatement

1.1 Purpose

The purpose of this documents are as noted hereunder:

a) to construct additional sewers as part of the existing combined sewer improvement

b) replacement of sewers as a part of the existing combined sewer improvement

c) construction of secondary interceptor sewer

The following drawings are applicable to the contents of this document:

a) Contractor’s Drawing No GE - T - 1xx “Existing Utility Survey / Protection”

b) Contractor’s Drawing No.’s L#1 - P - 1xx “Plan and Profile of ECSI”

c) Contractor’s Drawing No.’s L# - P - 2xx “Cross Section of ECSI” d) Contractor’s Drawing No.’s L# - P - 3xx “Plan and Profile of ISC” e) Contractor’s Drawing No.’s L# - P - 4xx “Cross Section of ISC” f) Contractor’s Drawing No.’s L# - P - 6xx “Structure of Inlet Pit / Manhole / DC”

g) Contractor’s Drawing No.’s L# - P - 7xx “Reinforcement Arrangement of Inlet Pit / Manhole / DC”

h) Contractor’s Drawing No.’s L# - T - 4xx “Shoring Section, Shoring Plan and Profile”

i) Contractor’s Drawing No.’s L# - T - 5xx “Excavation Scheme and Traffic Control Plan for Main Works”

2 SCOPE OF WORK

This scope of works associated with the Existing Combined Sewer Improvement (Including Secondary Interceptor Sewer) are outlined in Tables 2.1, 2.2 and 2.3 hereunder and on page 5 For a pictorial

presentation of the works reference is also made to Appendix No 1

M ANHOLE (N O )

C AST IN S ITU

C ONCRETE ( M 3 )

Table 2.1 Combined Sewer Improvement

2,0004

M ANHOLE (N O )

C AST IN S ITU

C ONCRETE ( M 3 )

Total Length: 9,220.00 metres

Table 2.2 Secondary Interceptor Sewer and Diversion Chamber

M ANHOLE (N O )

C AST IN S ITU

C ONCRETE ( M 3 )

Table 2.3 Existing Manhole and Inlet Pit

M ANHOLE (N O )

C AST IN S ITU

C ONCRETE ( M 3 )

M ANHOLE (N O )

C AST IN S ITU

C ONCRETE ( M 3 )

Works will commence at Line 4 An Duong Vuong Street and proceed along Le Hong Phong Street upto Manhole ref: M10 Thereafter the work team will re-locate to Line 1 to complete this line prior to re-mobilising to Line 4, Le Hong Phong Street, to complete the works from Manhole ref: M10 to M01.

Works will commence at Diversion Chamber No 16 and proceed along Tran Binh Trong Street upto the completion of the line at Manhole ref: Line 3 - M01 Thereafter the work team will re-locate

to Line 2 to complete the works at Nguyen Bieu Street commencing from Diversion Chamber No 15 The Secondary Interceptor Sewer works located along lines 2 and 3 will be executed at the same time as the Existing Combined Sewer Improvement works (with the exception of the range between M15

- 1 to M15 - 2 which will be executed separately).

Works will commence at Diversion Chamber No 17 and proceed along Huynh Man Dat Street, An Duong Vuong Street and Su Van Hanh Street The Secondary Interceptor Sewer works located along line 5 will be executed at the same time as the Existing Combined Sewer Improvement works.

Works will commence at Manhole ref: M65 on Mac Cuu Street and proceed along Chau Van Liem Street, Thuan Kieu Street, Le Dai Hanh Street, 3 Thang 2 Street and Ly Thuong Kiet Street.

One work team will be mobilised to each front, as highlighted above, and the works will be executed in blocks of approximately 200m For each stage of the work traffic control plans, including the construction schedule and the diversion procedure will be submitted

to the Department of Transportation and Public Works (DTPW) for approval The works shall be arranged on the road occupancy permission received from the relevant Government Authorities.

Existing drainage facilities shall be maintained during the course of execution of the works.

3.2 Care of Water

a Downstream portion of line constructed first;

b Mainline pipe upstream of construction area (Part 1) is blocked and the flow is diverted around the area under construction into the completed downstream portion;

c Upon completion of Part 1 the completed lines and inlet branches are opened for use;

d Mainline pipe upstream of construction area (Part 2) is blocked and the flow is diverted around the area under construction into the completed downstream portion;

e Upon completion of Part 2 the completed lines and inlet branches are opened for use;

f Mainline pipe upstream of construction area (Part 3) is blocked and the flow is diverted around the area under construction into the completed downstream portion;

g Upon completion of Part 3 the completed lines and inlet branches are opened for use;

The sequence above is repeated until the line in question is completed.

CONCEPT FOR CARE OF WATER (ADDITIONAL LINE)

a Downstream portion of line constructed first;

b Mainline pipes upstream of construction area (Part 1) are blocked and the flows are diverted around the area under construction into the completed downstream portion;

c Upon completion of Part 1 the completed lines and inlet branches are opened for use;

d Mainline pipes upstream of construction area (Part 2) are blocked and the flows are diverted around the area under construction into the completed downstream portion;

e Upon completion of Part 2 the completed lines and inlet branches are opened for use;

f Mainline pipes upstream of construction area (Part 3) are blocked and the flows are diverted around the area under construction into the completed downstream portion;

g Upon completion of Part 3 the completed lines and inlet branches are opened for use;

The sequence above is repeated until the line in question is completed.

For a pictorial representation of the above procedure reference is made to the drawing on page 9 hereinafter.

Inlet Manhole

Flow

Flow

Flow Flow Flow

Flow Flow

Construction Scheme for Improvement of Existing Sewer

Flow Manhole Inlet

Inlet Flow

Flow Flow Flow

Flow Flow

New Sewer Line

Flow Flow Flow

Flow

Flow Flow Flow

Flow

Temporary Diversion

Manhole Manhole

Manhole Manhole

Existing Sewer Line

Inlet Inlet

Flow Flow

Flow Flow

Flow Flow Flow

Flow Flow

Flow

Flow Flow

Flow Flow Flow

Flow Flow Flow

Flow Flow

PART 2 Under Construction PART 1 Under Construction

New Sewer Line

in service

(PART 2 Completed) (PART 1 Completed)

Temporary Diversion Temporary Diversion

Temporary Diversion

Construction Scheme for Improvement of Existing Sewer

Replacement

3.3 Flowchart

The flowchart detailed on page 10 hereinafter shows the basic sequence of works for each section of the Existing Combined Sewer Improvement (including Secondary Interceptor Sewer):

Excavation

MobilisationFence / traffic diversionCutting of existing pavement

Shoring systemProtect existing affected utilities

Pipe / box culvert installation

Manhole construction

Backfilling

Extract sheet piles

Road reinstatement

Sand bedding and leveling

concreteBase slab concretePipe installation or box-

Wall and top slab concretePipe installation to box-

Backfilling

Manhole shaft concrete

BackfillingExtract sheet piles

3.4 Preparatory Works, includes all necessary permits from relevant Government Authorities shall be obtained by the Contractor at his own expense, prior to commencement of the works.

The contractor will submit the road occupancy application together with detailed schedule including diversion procedure for each section / portion of work to the Department of Transportation and Public Works (DTPW) for approval.

After receipt of DTPW road occupancy permission, the construction area which is covered by the approved road occupancy application will be handed over from Urban traffic Management Organization (UTMO).

Traffic control devices shall be implemented in accordance with the provisions of Decision No 47/2005/QD-UB issued by PC HCMC on 24 March 2005

Safety Fence and Traffic Control Devices will be set-up in accordance with the road occupancy application approved by DTPW as outlined hereinabove.

Permit shall be posted on the safety fence when the construction work commences to inform the public that the works possess the appropriate permission for execution.

Prior to commencement of the works, for coordination purposes, and if deemed necessary, a meeting may be held for each particular area / district with attendance from the representatives of the People’s Committee to inform them about the project including the anticipated working schedule and associated road occupancy permission.

3.4.2 Existing Utility Survey

The test pits to determine the location of existing services which may be affected by the Works are classified into two types as noted hereunder:

a) Type 1 - Services lying parallel to the location of the Works b) Type 2 - Services lying within the area of the Works

Type 1 test pits are executed to determine sheet pile arrangement while Type 2 are utilised to identify services within the works area.

For further details reference is made to the Contractor’s approved Method Statement for Utility Service Survey MS-003- 01.

Table 3.4.2 on Page 12 hereinafter summarises a list of responsible entities pertaining to existing services together with authorised contact staff members and details as appropriate.

Table 3.4.2 List of Responsible Entities and Contact Details

Company

2 Hung Vuong, District 10

8 Bis Pham Ngoc Thach, District 1

Chu Quoc Huy

Mr Khan

General DirectorEngineer

1 Cong Truong Q

Te, District 3

Bach Vu HaiNguyen Van Toan Chau

Tran Van Thuong

Vice DirectorStaff

DirectorStaffStaff

63 Ly Tu Trong, District 1

Tran Quang PhuongNguyen Viet Son

DirectorVice Director

Company

12 Thi Sach,

Company

1a Thuan Kieu, District 5

9555 - 998

If some existing utility(ies) require temporary, or perhaps even permanent diversion, to permit the execution of the Works the Engineer shall instruct the Contractor to execute the diversion

or re-location in accordance with the Responsible Entity(ies) directions / instructions or arrange for a contract with the Responsible Entity to carry out the required works After discussions between the representatives of the Employer and the Responsible Entity have been finalised, such diversion will

be indicated in the drawings or advised in writing by the Engineer prior to the commencement of works near the utility,

as prescribed in Sub-Clause 1.9.4.4 of Section 1, Division A, Volume 2 “Specifications”.

The Contractor shall take all necessary due precautions to prevent damage to any existing utility which may be affected

by the execution of the Works.

Nevertheless, in the event that any service is damaged as a direct result of the Contractor’s operations the following contingency plan shall be implemented:

a) Authorised representative(s) from the Utility Owner shall be immediately contacted by the quickest means possible to advise of the actual situation on Site

b) Representative(s) of the Employer and Engineer shall be subsequently advised if they are unaware of the situation c) If possible temporary measures2, as advised by the authorised representative(s) from the Utility Owner, shall

be implemented as soon as reasonably possible d) Upon further inspection by the authorised representative(s)

of the Utility Owner further concrete reinstatement measures shall be discussed and agreed within the shortest possible timeframe

e) Once reinstatement measures have been agreed they shall

be implemented as soon as reasonably practicable under the close supervision of the authorised representative(s) of the Utility Owner

f) Once reinstatement measures have been completed a joint inspection by the authorised representative(s) of the Utility Owner, the Employer, the Engineer and the Contractor

2 Such measures may involve temporary disconnection of the utility in question if soapproved by the authorised representative of the Utility Owner

shall be conducted to confirm completion of the reinstatement measures

The designed location of the sewer pipe and box culvert alignment and designed coordinates of manholes, diversion chambers, inlets pits, and other structures shall be marked by the surveyor and inspected together with the Engineer This marking will identify whether or not existing structures may require adjustment / realignment of the section of works in question as prescribed in Sub-Clause 1.3.3 of Section 1, Division A, Volume 2 “Specifications”.

After the alignment setting-out has been completed and prior

to commencing excavation works for the area in question the existing ground elevation shall be checked and recorded.

Reference points, to be used for one particular section / portion

of the works, will be set-out and marked from the agreed control points.

3.4.4 Temporary Fencing and Traffic Maintenance

The proposed temporary safety fence and to be erected shall require the approval of relevant Government Authorities in accordance with the specification sub-clause 1.11 2.4 Safety fence shall consist of black colour iron tubular frame to which green colour galvanised corrugated steel sheeting is attached The fence shall be made up of panels with each panel being 2,000mm in length by 1,800mm in height Each post shall be provided with a concrete base for stability.

Typical signage which will be required during construction are:

• Vehicle prohibited to turn left / right

• Keep right / left

Danger Deep Excavation (Nguy hiể m Hố đà o sâ u)

GREEN STEEL SHEET

TY PIC AL LAY -OUT

EXC AVATION AREA

To maintain traffic flow the Contractor shall follow the plan approved by the Department of Transportation and Public Works (DTPW) and shall closely liaise and co-ordinate therewith during the course of execution of the works.

Cutting of the existing road pavement will be executed using concrete cutter An allowance of 200mm from the outer face of the sheet pile is preferable to prevent any damage of the existing asphalt pavement The existing pavement shall be cut straight and parallel to the construction area to provide a uniform edge.

After cutting the asphalt pavement shall be removed from Site, either using mechanical or manual means depending upon the space available, and disposed of accordingly.

3.5 Excavation Work and Temporary Shoring

Based on the results of the soil investigation works undertaken the shoring systems for each area of work shall be designed and Contractor’s drawings reflecting the same shall be developed and submitted for approval.

After completing the check of utilities within the works areas driving of sheet piles shall be commenced.

A guide frame, consisting on two h-beams, shall be laid on the ground to provide a guide for the sheet pile location Sheet piles shall be driven by vibratory hammer affixed to an excavator shall be joints firmly secured The vertical alignment

of the sheet piles shall be checked during driving.

To prevent twisting of the sheet pile within the guide frame outlined above the free leg of the U - type shall be secured by a guide block during the driving process.

In the event any existing overhead electric lines exist within the area of the pile driving machine the lines shall be covered

by an appropriate insulation cover to prevent arcing or electric shock.

The sequence described hereinabove is repeated until the sheet piles for the works area in question are completed.

3.5.2 Care of Water

As outlined previously in Sub-Article 3.2 hereinbefore the concept for care of water is to divert the flow of water from the upstream to the downstream while constructing a additional line or replacing the existing line The outline of the procedure

is as noted hereunder:

• The upstream portion of the pipe is blocked

• A water pump, together with sufficient length of hose, is set-up to pump out the water from the upstream side to the downstream side An illustrated example of this principle, for Line 6, is shown on page 17 hereinafter:

3.5.3 Excavation including Dewatering and Shoring Erection3

At predetermined points during excavation works, waling and struts supports shall be installed in accordance with the approved temporary works design Walers and struts shall be firmly fixed in position at the required locations Excavation shall be continued until the desired elevation is reached.

In order to ensure dry conditions during construction an open drainage ditch shall be formed at the side of the trench to a pre-determined location where a sump pit shall be excavated From the sump pit the water shall be pumped out to the nearest existing drainage system by suitable capacity pumps The number and capacity of pumps shall be chosen based on the actual prevailing conditions during construction Either gasoline or electric type pumps shall be utilised for this purpose Standby pumps shall be available on Site in the event they are required during particularly heavy precipitation.

In the event the excavation of the trench is particularly wide and the working space is restricted steel plates shall be arranged to facilitate the movement of plant and equipment within the works area.

The illustration hereunder outlines the typical sequence of excavation and temporary shoring installation:

3.5.4 Protection of Existing Utility

3 Elevation of each level of strut and waling support is determined in accordance with theapproved temporary works design

STEP 1 STEP2 STEP3

In accordance with Sub-Clause 1.9 of Section 1, Division A, General of Volume 2 “Specifications” existing utilities will require protection This sub-article explains the typical protection method in this respect For a pictorial representation thereof reference is made to the Contractor’s Drawing No GE - T - 103 “Existing Utility Protection”.

Drainage and Water Pipe Utilities

A steel beam / pipe shall be laid across the road surface and

hung from the beam using metal chains at the required intervals The chain can be tightened or loosened as required

by using a sufficient quantity of tying wire twisted and tied to the chain or, alternatively, by using a turnbuckle.

Electric and Telecom Cable Utilities Principally the same method as above will be used.

Drainage Brick Arch Utility Due to uncertainties surrounding the existing brick arch detailed protection / diversion measures will be submitted separately, at a later date, after completion of the test pits whereupon further information can be obtained.

As far as can be ascertained by the Contractor the Department

of Natural Resources and Environment (DONRE) stipulate the requirements hereunder noted for disposal of excavated material:

• The Contractor shall prepare drawing(s) showing the location of the disposal area together with a letter of request for their approval

• After receipt of approval from DONRE the Contractor shall submit the authorised permit to the Engineer and Employer

• The Contractor shall comply with the requirements of Decision No 156 QD-TNMT issued by DONRE

Based on the anticipated working schedule the volume of disposal material is in the region of 200m3 per day In this respect the Contractor shall select dump trucks of sufficient capacity to maintain continuous excavation of the required works areas.

Before any trucks leave the works area location the wheels and body of the truck will be washed down with water and the excavated material will be trimmed down and covered with a canvas sheet to prevent spillage during transportation.

3.6 Pipe and Box Culvert Installation

The pipe and box culvert will be transported to their final location and lowered down into position by excavator or crane (with suitable attachment) Lowering shall be carefully controlled to ensure that the possibility of damage to the pipe / box culvert will be minimised Details of the crane to be utilised are included within Sub-Article 5.4

of this document.

Sand bedding4 shall be placed in layers not exceeding 200mm

in thickness and suitably compacted by a vibratory plate compactor or tamping rammer for the full width of the trench During the installation of the pipe / box culvert the second level

of waling and strutting support5, if present, shall be removed and the sheet piles shall be supported on both sides and on the inside of the pipe / box culvert A pictorial representation of this method is presented hereunder:

4 Only approved sand material shall be used

5 Elevation of each level of strut and waling support is determined in accordance with theapproved temporary works design

A

NEW STRUT

After completion of installation of the pipe / box culvert section

in question sand filling will be placed in layers, not exceeding 100mm unless otherwise approved by the Engineer, upto a level of 200mm (minimum) above the crown of the pipe / box culvert The sand filling shall be suitably compacted by a vibratory plate compactor or tamping rammer for the full width

of the trench.

Sand bedding shall be placed in layers not exceeding 200mm

in thickness and suitably compacted by a vibratory plate compactor or tamping rammer for the full width of the trench Prior to installing the pipe, pipe saddles (2 number per pipe) shall be placed Once secured, the pipe section in question shall be laid and the invert elevations shall be checked and confirmed.

Thereafter formwork for the concrete bedding shall be placed and concrete (Grade F) shall be cast to the required levels At defined junctures, the pipe saddles shall be removed The concrete shall conform to the approved mix design and shall be batched off-site at an approved batching plant and transported

to the required location by transit mixer For a typical presentation of the bedding type C120 and C180 reference is made to the illustration hereunder.

A A

3.6.3 Box Culvert including Jointing Works

Jointing concrete (Grade F) shall be formed around each joint and shall be allowed to cure for at least seven (07) days.

Segments of the box culvert shall be carefully placed on the sand bed to ensure that adjacent units are properly jointed and that the concrete under the joint is in contact with the joint For typical details in this respect please refer to the pictorial presentation hereinbelow.

PLAN

A

JOINT CONCRETE

WORK DIRECTION

3.6.4 Alignment and Profile Control

As outlined in Sub-Article 3.4.3 hereinbefore the design location shall be set-out by the surveyor and checked by the Engineer Reference points will be set-up with nails installed in the pavement adjacent to the construction area prior to commencing excavation works The alignment and profile control will be based on these reference points.

For each area of work the surveyor will set out, from the reference points, four points on the sheet pile at both sides of the trench The intervals of each set of four points will basically be 20m.

Once excavation works are complete the bottom elevation of the trench will be checked by taking accurate measurements Once the first layer of sand bedding has been completed and after completing the compaction of the second layer of sand bedding the upper elevation of the bedding will be checked by taking accurate measurements Such checks will be carried out

at 2 metre intervals along the length of the pipe / box culvert section in question In the event any discrepancy between the design elevation and the actual elevation is identified as exceeding the permitted tolerances sand bedding material can

be added / removed as required.

Once the pipe / box culvert section has been placed the invert elevation of each will be checked against the approved working drawing by taking accurate measurements thereof.

The alignment of the pipe / box culvert will be maintained by transferring points into the trench, using a total station, at positions sufficiently close to the crown of the pipe A string line will then be installed through such points and the alignment of the pipe can subsequently be confirmed visually 3.7 Construction of Manholes and Inlet Pits shall be set-out according to its designed coordinates.

Where the Contract calls for the demolition of existing manholes / inlet pits such demolition shall be executed after the relevant temporary trench shoring systems6 have been installed and the diversion of water within the existing connection pipe have been completed.

Thereafter the structure shall be demolished by jackhammer or other suitable means As far as reasonably possible the structure shall be broken into small pieces for ease of transportation and disposal

Sand bedding, thickness of 200mm, will be placed to the underside elevation of the manhole / inlet pit in layers not exceeding 100mm in thickness, suitably compacted by a vibratory plate compactor or tamping rammer.

Levelling concrete, Grade G thickness = 100mm, shall be placed in accordance with the construction and approved working drawings.

3.7.3 Formwork and Falsework Installation

Formwork shall be constructed so as to be strong enough to withstand pressures during concrete placement and shall be constructed from either timber of metal.

Formwork shall be properly equipped with braces, ties and other devices such that the designed profile of the structure can be maintained at all times.

All formwork installed shall be free from dust, grease and shall

be treated with approved form oil prior to placing of reinforcement.

be left in contact with the formwork Welding of reinforcement

6 Either steel or timber depending upon the area in question

shall not be permitted unless previously approved by the Engineer.

Concrete spacer blocks shall be installed at pre-determined intervals in order to maintain the required concrete cover.

Immediately prior to concrete pouring all rust, oil, paint and other deleterious substances which may affect bonding shall be removed from the reinforcement.

3.7.5 Concrete Placing (including surface finishing, construction joint)

Concrete mix is Grade E for reinforced concrete.

Concrete shall be placed using short chutes and shall not be dropped over a vertical distance exceeding 1.5 metres to ensure that no segregation of the concrete constituents occurs and the possibility of displacement of reinforcement is minimised.

Prior to casting fresh concrete the surfaces of any construction joints shall be washed and brushed with wire brushes to expose clean aggregate The surface shall be kept wet at all times upto the casting of the fresh concrete.

Concrete shall be transported to the required location by transit mixers and shall be placed in the forms by concrete boom, chute or bucket.

Concrete shall be compacted utilising internal vibrators and vibration shall be carried out in such a way that contact with reinforcement and formwork shall be minimised.

After compaction is completed the vibrators shall be slowly withdrawn.

Care shall be taken to avoid over vibration.

Curing of concrete surfaces shall commence after any surface water has completely disappeared After removal of formwork the entire concrete surface shall be covered with wet burlap material and shall be kept moist during the entire curing period

at least seven days In the event any repairs are required to the concrete surface the burlap may be removed temporarily to permit such repairing but shall be replaced immediately upon completion thereof Alternatively, curing compound may be used if permitted by the Engineer.

Formwork may be removed in accordance with the following conditions:

• Floor Slabs - the result of the concrete strength test on the specimen cubes exhibits strength exceeding 70% of the design strength

• Walls - after 24 hours The drawing hereinbelow illustrates the concrete casting sequence for the manholes / inlet pits.

3.7.7 Pipe Connection (Pre-install / Box Out & Install)

Two alternatives are available for the connection of the pipe to the manhole / inlet pit as noted hereunder:

After completion of casting the bottom slab the pipe can be installed prior to the installation of the wall formwork

• Box Out & Install

A box-out will be formed within the wall formwork at the required location After completion of casting of the wall the box out is removed Thereafter the pipe / box culvert is connected to the manhole / inlet pit and the remainder of the box-out is filled in accordingly.

3.8 Construction of Diversion Chambers

The flowchart detailed on page 26 hereinafter shows the basic sequence of works for the construction of the Diversion Chambers called for by the Contract.

Benching

Sand bedding and leveling

concrete

Base slab concrete

Pipe installation or box out

Main sewer line, secondary line, diversion chamber and inserting pipe and flap gate

Wall concrete

Pipe installation to box out

Main sewer line, secondary line, diversion chamber inserting pipe

Top slab concreteBackfilling

Manhole shaft concreteBackfilling

Plain Concrete (Class F) shall be placed in the bottom of the manhole as prescribed on the construction drawings.

The upper surface of the benching shall be finished with 20mm thick granolithic topping in the ratio of 1:2 cement : granite mix The maximum size of the granite chips is 6mm.

Prior to applying the topping the surface of the concrete shall be wire brushed to remove laitance and any loose materials and shall

Prior to commencing any backfilling works preceding materials i.e formwork, or similar shall be removed from the area in question The material to be utilised is “sandy soil”, the material source for which, together with test result, should be submitted to the Engineer for approval prior to use in accordance with Sub-Clause 3.4.2 b) of Section 3, Division B, Volume 2 “Specifications” The soil testing programme is

included within Appendix No 5.

Sand backfilling shall be placed in layers not exceeding 150mm

in thickness according to Sub-Clause 3.4.7 of Section 3, Division B, Volume 2 “Specifications”, spread manually and suitably compacted by a vibratory plate compactor or tamping rammer Backfilling shall be continued until the underside level

of the pavement to be reinstated is reached.

Backfilling shall be wetted in order to achieve optimum moisture content for compaction Backfilling material shall be compacted to 90% of the maximum dry density as determined

in laboratory compaction tests for the material in question 3.9.3 Extraction of Temporary Shoring7

7 Elevation of each level of strut and waling support is determined in accordance with theapproved temporary works design

If a second level of temporary walers and struts is required by the temporary shoring design this level shall be removed during installation of the pipe / box culvert (for further details refer to Sub-Article 3.6.1 hereinabove) Other levels of walers and struts will be removed as the backfilling reaches the required level.

If sheet piling temporary shoring is installed it shall be removed when the backfilling level reaches 70% of the height of the trench excavation At this juncture it can be determined whether any settlement will occur.

During the extraction procedure each sheet pile shall, as far as reasonably possible, be kept in a vertical position and extraction shall be guided by a spotter who shall keep the operator informed of the progress of the works to ensure correct and safe extraction Once extracted the sheet piles shall be moved to the next location.

3.10 Leakage Test

After completion of removal of the temporary shoring system and restoration of the normal sub-surface conditions the pipe / box culvert and manhole will be visually checked to see if there is any infiltration resulting from the pressure of the underground water In the event any infiltration is detected it shall be manually measured.

In accordance with Sub-Clause 7.9.4 of Section 7, Division B, Volume

2 “Specifications” the acceptance criteria is stated as being not exceeding 0.5 litre per linear metre per metre of nominal bore (for circular sections) / per metre width (for rectangular sections including manholes).

3.11 Repair of Concrete

Concrete repair may be classified in the following categories:

1 Cracks Through the wall

and slab

should be undercut in a U-shape

by at least 25mm beneath the surface of the concrete using a

C LASSIFICATION C RITERIA P ROCEDURE

3 Minor defects Other than those

1 4

1 6

1 8

2 0

2 2

2 4

2 6

2 8

3 0

3 2

3 4

3 6

Chief Engineer

Coordinati

on Officer

Chief Engineer

SurveyorCAD

operator

5.2 Suppliers / Sub-Contractors

The list of relevant sub-contractors / suppliers shall be informed by the Contractor under separate cover.

5.3 List of Machinery / Equipment

work

i.e welding machines, concrete vibrator, bar cutter, pumps etc

5.4 Crane Capacity

The maximum capacity of the crane shall be 25 tonnes Please

refer to Appendix No 2 for details in this respect.

8 Estimated only, subject to actual Site condition for each given area and available space

9 8 Estimated only, subject to actual Site condition for each given area and availablespace

9 For road reinstatement only

All works associated with the Existing Combined Sewer Improvement (including Secondary Interceptor Sewer) shall comply with the requirements of the Management System and Quality Control Plan, as may be amended from time to time.

6.1 Inspection and Test Plan

This plan deals with the construction activities for one set of work including outlining the frequency of internal and joint inspections Concrete Quality

All concrete shall be ready mix supplied from an approved off-site batching plant All concrete shall be monitored to ensure good quality and workability For further details of the quality control procedures in this respect reference is made to MS-005 Concrete Quality Control under separate submission by the Contractor.

Quality Programme for Reinforced Concrete Pipe and Box Culvert All finished pipes and box culverts will be subject to inspection at the factory prior to delivery to the Site and at the Site after delivery and prior to installation For the relevant control procedures in this

respect reference is made to Appendix No.’s 3 and 4 attached

herewith.

Inspection and Test Plan for Site Works

Appendices No.’s 5 and 6 hereto outline, respectively, the

Inspection and Test Plan applicable to the Existing Combined Sewer Improvement (Including Secondary Interceptor Sewer) and the Inspection Checklist(s) / Form(s).

Appendix No 5 hereto nominates the inspection steps to be

implemented in order to ensure that the required quality, and

substantiating records, are maintained while Appendix No 6

details the inspection records which are to be completed, maintained and filed on Site.

From Decree No 209 three forms are applicable to the “Open Cut” construction work - Forms 4A, 5A and 7.

• Form 4A - to be utilised for the completion of each specific item of work such as excavation, bedding, pipe laying, concreting etc.

• Form 5A - for the completion of all construction work in one particular set

construction work for Line 1 to 6 6.2 Non-Conformance Report

During the execution of the works, if a written complaint, via a site Instruction or similar, is received from the Engineer or the Employer, and the complaint is justified then action will be initiated by the Contractor A Non-Conformance Report shall be completed and a record thereof shall be retained by the Contractor.

All works described herein shall comply with the requirements of the approved Occupation Health, Safety and Rehabilitation Plan and Project Safety Plan.

Specific Safety considerations:

a) Working under heavy traffic conditions

Diversion schemes shall be provided in accordance with the requirements of the DTPW office and the regulations in the Decision

of the People’s Committee of HCMC 47/2005/QD-UB dated 24 March 2005.

Proper illumination / lights shall be provided if the works are executed at night.

Watchmen and traffic controllers (if required) shall wear reflective clothing.

b) All workers shall wear appropriate PPE, i.e helmet, shoes, gloves etc as appropriate and deemed necessary in accordance with the PPE matrix contained within the Project Safety Plan

c) First aid facilities shall be available

Appendix No 7 hereto includes the completed Safety Risk Assessment

for the Existing Combined Sewer Improvement (Including Secondary Interceptor Sewer) Works.

All works described herein shall comply with the requirements of the approved Environmental Management Plan.

Specific Environmental considerations:

a) Good housekeeping practices shall be implemented i.e management of waste and the like

Appendix No 8 hereto includes the completed Environmental Risk

Assessment for the Concrete Works.

APPENDIX NO 1 LOCATION MAP