TECHNICAL DEPARTMENT-CIVIL (Replace by the Project Doc. No.

TEC-221300-MET-DoR-002
Name) (Rev No.)
METHOD STATEMENT Issue Date 02 October 2013
Rev. Date NA
Method statement for drainage & Sewage works
Pages 1 of 16

METHOD STATEMENT FOR DRAINAGE AND SEWAGE

WORKS

PROJECT : (Replace with the project’s name, at location , city name)

CLIENT : (Replace with the client’s name)

MASTER DEVELOPER : (Replace with the master developer’s name)

PMC : (Replace with the PMC’s name)

LEAD CONSULTANT : (Replace with the lead consultant’s name)

SUB-CONSULTANT : (Replace with the sub-consultant’s name)

MAIN CONTRACTOR : (Replace with the main contractor’s name)

SUB-CONTRACTOR : (Replace with the sub-contractor’s name)

TABLE OF CONTENTS
1. REVISION RECORD..........................................................................................................................................4
2. PURPOSE..........................................................................................................................................................5
3. SCOPE...............................................................................................................................................................5
4. REFERENCES...................................................................................................................................................5
4.1. Contract documents.......................................................................................................................................5
4.2. Contractors Submittal....................................................................................................................................5
5. DEFINITIONS / ABBREVIATIONS.....................................................................................................................6
5.1. Definition........................................................................................................................................................6
5.2. Abbreviations.................................................................................................................................................6
6. RESPONSIBILITIES...........................................................................................................................................6
6.1. Project Manager.............................................................................................................................................6
6.2. Site Engineer.................................................................................................................................................7
6.3. Project Engineer............................................................................................................................................7
6.4. QA/QC Engineer / Inspector..........................................................................................................................7
6.5. Surveyor.........................................................................................................................................................7
6.6. HSE Engineer/Officer.....................................................................................................................................7
6.7. Foremen/ Works Supervisor..........................................................................................................................8
7. EQUIPMENTS/ TOOLS / MANPOWER/MATERIALS........................................................................................8
7.1. List of Equipment’s/Tools...............................................................................................................................8
7.2. List of Manpower............................................................................................................................................8
7.3. List of Materials..............................................................................................................................................8
8. GENERAL PROCEDURAL MATTERS..............................................................................................................9
8.1. Dewatering.....................................................................................................................................................9
8.2. Where Rock Is Encountered..........................................................................................................................9
9. PROCEDURE FOR CONSTRUCTION OF GRAVITY SEWER LINES PIPE LAYING....................................10
9.1. Procedure for Water Test for GRP Pipes....................................................................................................11
9.2. Procedure for the Storage of Pipes.............................................................................................................12
9.3. Procedure for backfilling..............................................................................................................................12
9.4. Procedure for concrete bed & surround for GRP pipes...............................................................................12
9.5. Procedure for construction of chambers......................................................................................................12
9.6. Procedure for construction of manholes......................................................................................................13
9.7. Procedure for backdrop construction...........................................................................................................14
9.7.1. Material approved for backdrop construction...............................................................................................14
9.8. Procedure for reinforcement works..............................................................................................................14
9.8.1. Machineries and tools required for reinforcement works.............................................................................14
9.9. Procedure for waterproofing works..............................................................................................................15
9.9.1. Approved material for water proofing works................................................................................................15
9.9.2. Tools required for water proofing works......................................................................................................15
9.10. Procedure for fixing DI cover & frame..........................................................................................................16
9.10.1. Tools required for fixing DI cover and frames.........................................................................................16
9.11. Procedure for GRP manhole liners..............................................................................................................16
9.11.1. Material required for site GRP lamination...............................................................................................17
10. STORAGE REQUIREMENT............................................................................................................................17
11. HEALTH, SAFETY AND ENVIRONMENT.......................................................................................................18
12. ATTACHMENTS...............................................................................................................................................18
12.1. Inspection Checklists...................................................................................................................................18
12.2. Inspection Test Plan....................................................................................................................................18
12.3. Risk Assessment.........................................................................................................................................18
12.4. Technical Data sheet (TDS)........................................................................................................................18
1. REVISION RECORD
This page is a record of all revisions of the document identified below by number and title. All
previous revisions are hereby superseded and are to be destroyed.
Rev Date By Chkd. Approved Description of Revisions
0 First issue

Signature field
Revision
Revision
Number
Date
Prepared by Checked by

Reviewed
By Construction Technical QA/QC MEP Co- Sub-
Manager Manager Engineer HSE Officer ordinator contractor

Approved
By Project
Manager
2. PURPOSE
The purpose of this Method Statement is to define the procedure for the preparation and construction of
Gravity Sewer lines with GRP pipes with associated inspection chambers, manholes in accordance with the
requirements specified in the relevant specifications specification 220000considering safety and quality of
the work activities.

3. SCOPE
1. Gravity sewer lines of about 2.1 Kms with 36 manholes 1500mm dia. Associated with house connection
chambers to facilitate the project.
2. The G.R.P pipes 150mm dia. 1173 Mts, 200mm dia. 191 Mts and 300mm dia. 241 mts. Laid in a trench
width of 600mm + pipe diameter in a stable soil and 5 times pipe diameter in unstable soil.
3. The limit of contract is gravity feed connection to the pumping station constructed by others adjacent to
project boundary.

4. REFERENCES
4.1. Contract documents
1. Project Specification :- Division 22, Section 221300
2. Contract Drawings :-

4.2. Contractors Submittal

3. Project Quality Plan :-
4. Project Safety Plan :-
5. Relevant standards and specifications as issued by ADSSC

6. Material approvals
Sr. No. Description Material Sub. No. Rev No. Date Remarks
1
2
3

7. Shop Drawings
Sr. No. Description Shop Drawings Rev No. Date Remarks
1
2
3

8. Related method Statements

Sr. No. Description MET no. Rev No. Date Remarks
1
2
3

5. DEFINITIONS / ABBREVIATIONS
5.1. Definition
1. Project -(Replace with project name)
2. Client -(Replace with clients name)
3. Developer -(Replace with developers name)
4. Consultant -(Replace with consultants name)
 5. PMC -(Replace with PMC name)
6. Contractor -(Replace with contractors name)
7. Sub-contractor -(Replace with sub-contractors name)
8. Supplier -(Replace with suppliers name)

5.2. Abbreviations
1. Engineer - Representative of “Name of engineering consultancy”
2. ADSSC -Abu Dhabi Sewage Services Company
3. ICL - Inspection Check List
4. IR - Inspection Request
5. ITL -Independent Testing Laboratory
6. ITP - Inspection and Test Plan
7. ITR -Inspection & Test Requests
8. MAT - Material Submittal
9. MEP - Mechanical Electrical Plumbing
10.MET - Method Statement
11.MIR - Material Inspection Request
12.MSDS - Material Safety Data Sheet
13.PPE -Personal Protective Equipment
14.PQP -Project Quality Plan
15.PTW -Permit To Work ( Working at Height or enclosed spaces)
16.RA -Hazard Identification and Risk Assessment
17.RFIA - Request for Inspection and Approval
18.SPD - Shop Drawing
19.TBM - Temporary Bench Mark

6. RESPONSIBILITIES
6.1. Project Manager
1. Ensuring that the subject works in coordination with other works with the requirements of Quality
Plan & programme.
2. Ensuring the full compliance of subcontractors with Company Quality policies and with the
requirements of this method statement.
3. To ensure that all the equipment required to execute the works according to the construction
programme are available, in good condition, and provide any additional equipment that might be
required.
4. To co-ordinate with the Construction Manager, Project Engineer, Safety Engineer, Foreman and
Surveyor for a safe and proper execution of the works.
5. To guide specific attention to all measures in coordination with the safety Officer/Engineer.

6.2. Site Engineer

1. Ensure area is ready and safe to start the works.
2. Arrange for required Plant manpower & Equipment’s in arrangement with Project Engineer / Site
Foreman.
3. Liaise and co-ordinate with the Project Manager to execute the works as per approved drawings.
4. Coordinate with Safety Officer to maintain safe working & proper housekeeping of site all time.
6.3. Project Engineer
1. The Project Engineer will carry out his duties in a manner that will be coordinated by the Project
Manager on a daily basis, and will ensure proper distribution of construction groups.
2. To be aware of test frequencies related to the activities.
3. To control disposal of waste excavated material according to the instructions received from the Project
Manager.
4. To inform the QC Inspector of the areas ready for inspection and to prepare the RFIA with complete
attachments.

6.4. QA/QC Engineer / Inspector

1. Ensuring that Consultant/Client inspection requests are implemented.
2. Compilation of all necessary quality control checklists
3. Assisting Consultants during the Inspections.
4. The control of work performance by means of checking the work before consultants’ inspection and
issuing RFIAs & punch lists as necessary.
5. Completion of documentation to verify the work performed.
6. Controlling all inspection activities on-site in line with ITPs.
7. Ensuring that all test equipment including surveying equipment is calibrated and is suitable for use on-
site.

6.5. Surveyor
1. To establish benchmarks from agreed reference points, provide required setting out and level
markings and follow up with regular checks.
2. Co-ordinate with the Site Engineer / Foreman and ensure the approved shop drawings/construction
drawings will be implemented properly.
3. Maintain survey details and reports, periodically check the progressing works and advise the Project
Manager of any deviation from the drawings.

6.6. HSE Engineer/Officer

1. To have latest revision of drawing on site all times.
2. To ensure implementation of all safety measures related to the nature of works being carried out, and
in accordance with the Project Safety Plan.
3. To ensure that all the persons involved in the works are aware of their responsibilities, and that they
have enough understanding of the safety procedures.
4. The Safety Officer will report directly to the Project Manager, who will ensure that all the
recommended safety measures are implemented and maintain safe working on the site.
5. To maintain continuous inspections of the site activities, advise and train persons on a daily basis to
prevent accidents and personnel injury.
6. To give special concern to housekeeping, and ensure that the site is maintained clean and tidy.
7. To ensure all the relevant safety sign boards for different works are in place.

6.7. Foremen/ Works Supervisor

1. Ensure the works are progressed in the sequence as agreed with the Site Engineer.
2. Ensure ready mix concrete ordered from the approved supplier is delivered on time and with sufficient
quantity for continuous casting of the planned pour.
3. Liaise with the Project / Site Manager for the allocation of the work force, ensuring adequate
manpower is available.
4. Liaise with the site manager to ensure all the required plant / materials are available to construct the
works.
 5. Full time supervision will be required to ensure the works are progressing to the latest approved for
construction drawings and specification.

7. EQUIPMENTS/ TOOLS / MANPOWER/MATERIALS

7.1. List of Equipment’s/Tools
1. Transit Mixer (concrete supplier) from 8. Survey Equipment’s (Calibrated)
RMC company 9. Excavators
2. Vibrators 10. Wheel Loaders
3. Concrete Pumps 11. Dewatering Pumps & Accessories
4. Scrabblers /Chipping Gun 12. Plate compactors
5. Masonry tools 13. Safety Cones
6. Mobile Crane 14. Ladder
7. Concrete Buckets

7.2. List of Manpower

1. Project Manager 6. Lab Technician
2. Project Engineer 7. Foremen/Work Supervisors
3. Site Engineer 8. Equipment Operators
4. QA/QC Engineers/ Inspectors 9. Skilled and unskilled labourers
5. Safety Engineer/Officers

7.3. List of Materials

1. Ready mix concrete with approved design & trial mix of 40N/mm2 and 20N/mm2.
2. Reinforcement Steel Bars, Assorted sizes
3. 18mm thick Phenolic Board (Plywood)
4. Assorted Wood
5. Cover & Frame
6. Assorted Nails and Concrete spacer
7. Marker Tape
8. Tie Rods and Steel Clamps
9. Cup-Lock with Steel Decking and Infill System
10. 10mm Course Aggregates(natural)
11. Polyethylene sheets, Absorptive Mats and Water
12. Poly Release WB Mould/Shutter Release Agent.
13. Geotextile Filter Fabric

8. GENERAL PROCEDURAL MATTERS

1. Shop drawing for each line will be prepared and approved by Engineer prior to start the actual work.
1. Upon formal receipt of construction approval from the Engineer, setting out for the sewer lines will be
carried out by the Contractor’s Surveyor, which will be agreed with the Engineer’s Surveyor before
proceeding with any permanent work.
2. Any obstruction observed during site inspection will be recorded and photographed and confirmed in
writing for reference and records.
3. Work will proceed in the event the proposed sewer is unaffected by obstruction.
4. In the event of obstruction conflict of any kind, necessitating relocation outside the allocated sewer
reserve, the necessary permission for such relocation will be acquired by the Engineer.
5. Prior to dewatering, necessary approval will be obtained from the concerned authorities prior to
discharge in existing system. (Approved)
6. All operation will follow contractors Safety Manual, and when there are omissions, ADSSC Safety
manual will be followed.
7. Copies of approved QA/QC Forms will be used for all approval procedures.
8. General Method Statement for Construction of Gravity Sewer Line, Manholes & Chambers

8.1. Dewatering
1. Where formation levels are below the ground water table, we propose to dewater our excavation
utilizing well point dewatering system.
2. We shall pre-drill the wells using Drill head fitted to the boom of a wheeled or chain excavator.
3. The well-points of 6 m. in length will be installed into the pre-drilled holes using jetting pumps.
4. The slotted filter heads of the well-points will be surrounded with sharp filter sand while jetting.
5. 50 mm dia. UPVC well-points will be connected to 150 mm dia. Header pipes via 50 mm dia. Flexible
hoses. The header pipes will be linked to 150 mm dia. Vacuum pumps which will pump the
groundwater via 150 mm dia. Lay flat discharge lines, connected to 10” discharge lines laid up to
approved discharge points. (Through a setting tank) to avoid sand going to the existing system.

8.2. Where Rock Is Encountered

1. A well point dewatering system (as per (5.2.A) above) will be installed approximately for the first 30
metre length, in order to establish a sump, from where the ground water will be slumped out by
means of a suitable submersible pump or vacuum pump, if the formation area encountered by hard
soil. The available bore hole results will have due significance while deciding upon the method of
dewatering for a particular area.
2. General Method Statement for Construction of Gravity Sewer Line Manholes & Chambers
3. NOTES ON EXCAVATION
4. The Existing ground level will be recorded.
5. Excavation will proceed after successful dewatering wherever required
6. Where sewer lines are located in areas unaffected by space restriction and are in areas of stable
ground conditions, an open–cut excavation to the safe angle of repose of the soil will be adopted.
7. The deep excavation will be in stages as per depth band.
8. Where the proposed deep lines are located near an existing service or structure, we will use trench
shoring box support for excavation prior to commencement of any such excavation.
9. Due care will be taken to maintain and support all the existing services and structures.
10. A Night watchman will maintain a vigil on the excavation and dewatering installations, to keep the
excavation free of water or loose materials at all times.
11. Diversions will be carried out by safety barriers.
12. Access ladders or scaffolding staircase will be provided for ease of entry and exit from the excavations
every 25m.
13. Inspection requests, will be given to the Engineer/Inspectors, for obtaining approvals at various stages
in accordance with RFIA
14. The available bore whole results have due sign face upon the method of excavation and dewatering
for a particular area.
15. The excavated material will be moved to a safe distance from the trench sides.
16. Adequate shoring, battering of excavation sides will be undertaken to ensure the trench remains
stable & safe working environment.
17. Soft spots observed on excavation formation level will be notified to Engineer and replaced with
suitable material as directed by the engineer.
9. PROCEDURE FOR CONSTRUCTION OF GRAVITY SEWER LINES PIPE LAYING
1. Approved drawing shall be reviewed by the Project Engineer & communicated to foreman in charge
of pipe laying G.R.P. pipes are to be laid in accordance with the manufacturer’s instructions
concerning the laying of pipes and bedding for the same, as submitted for approval.
2. Written inspection requests will be given to the Engineer/Inspectors for approval of various stages
of work, such as –
a) Setting out
b) Excavation & formation
c) Side and above bedding
d) Pipe Laying (Alignment & Levels)
e) Water Test
f) Deflection Test (Ball test)
g) Backfilling
3. Upon receipt of the Engineer’s approval of the compacted formation, the bedding material will be
carefully placed in the trench on the spread geotextile (approved).
4. 10mm Granular bedding material will be spread and levelled to the pipe gradient to a level of 2cm
above the invert level, so as to have a compacted invert level.
5. The stacked pipes will be lowered carefully in to the trench and laid downstream to upstream.
6. Pipes will be laid in granular bed and surrounded by 10mm single size crushed aggregate, contained
within approved geotextile trench lining material.
7. The pipes will be checked for line and level jointly by our Surveyor and the Engineer’s inspector.
8. Each pipe joint will be enclosed with approved PVC wrapping tape.
9. Side bedding will be placed carefully by means of a crane and side discharge skip, discharging the
materials centrally. The side bedding will be compacted in 150mm layers, by 2 No. hand
compactors, simultaneously on either side of the pipe to impart symmetrical compaction. Care
must be taken that the compactor will not in any means have a direct contact with pipes to avoid
damages.
10. Following this, the pipe surround material will be placed carefully in the same manner, to a level of
30cm in two layers above the crown of the pipe and compacted. The Geo-textile Fabric overlap will
be 30cm.
11. Selected materials previously excavated from the trench will be utilized to backfill the trench in
250mm layers, carefully compacted by hand rammers , up to level of 600mm above the crown of
the pipe.
12. Water test in accordance with specification will be carried out as per the attached method
statement.
13. When pipe laying is not in progress, we will ensure that the pipe ends are closed at all times by
water-tight plugs.
14. Subsequently, backfilling will continue in layers, compacted in the lower regions by mechanical
plate compactors and in the upper region by hand operated drum rollers and where the trench is
wider than 2.0m a Banag vibrating steel “is-upon” roller shall be used.
15. Upon completion of the backfilling the 1st deflection test will be carried out (allowable limit: 3%)
16. A 2nd deflection test will be carried out immediately prior to PAC (allowable limit: 5%)
17. Compaction test will be carried out for the backfilling, as directed by the Engineer in unmade areas
to a minimum Proctor density of 90%. In areas under roads, the backfilling and compaction test will
be carried out in accordance with Abu Dhabi Municipality specification for backfilling of Trenches
and Excavation in Tiled/Paved Parking’s and Roads.
18. A final mirror test is carried out to ascertain the alignment.
 19. A 150mm wide service warning tape will be placed 800mm below FGL.

9.1. Procedure for Water Test for GRP Pipes

1. Complete the granular bedding up to the soffit of the pipe line
2. Fix stoppers end plugs both at the upstream and downstream with two pipes ½” dia. the upstream will
be “air release pipe’, while the downstream one will act as ‘filling pipe’
3. Fill the line from downstream pipe (Filling pipe)
4. Keep the Air Release Pipe open to release the air.
5. When water starts coming from the Air Release Pipe, the pipe will be closed.
6. A pump will be fixed at the downstream end, fitted with a gauge and pressure applied equivalent to
5m of water head or depth to invert plus 1.0m whichever is greater.
7. Measure the head at the down steam end.
8. The pressure will be maintained for a period of 30 minutes.
9. If there is any drop in pressure, water will be added from a measuring vessel at 10 minutes intervals.
10. A record will be kept of the quantity of water added.
11. The added quantity of water should not exceed 1 litre per day per millimetre of nominal internal
diameter, per kilometre of pipe.
12. Pipe line will be tested in length between manholes to manhole.
Method statement for Construction of Gravity Sewer Lines

9.2. Procedure for the Storage of Pipes

1. The Pipes & Fittings will be stored in a shaded area for G.R.P pipes with tarpaulins to protect from
direct sunlight and in accordance with manufacturer’s recommendations.
2. It will be ensured that the Pipes and fittings do not come into contact with sharp projections.
3. The pipes and fittings will be stored in a flat level area and raised above the ground on timber so that
the lowest point of any pipe or fitting is not less than 150mm above the ground.
4. The pipes will be stacked in such a manner so that the height of the stacked pipes does not exceed 2
meters.
5. The Spigot and Socket pipes will be stacked in such a manner so as to ensure that pipe layer have
sockets protruding at opposite ends of the stack.
6. Rubber Joint Rings will be stored in an air-conditioned store.
7. Only nylon slings shall be used for lifting pipes and units (Transportation / Installation)
8. Segregation of damaged products (if any) is brought to the notice of Engineer for either repair or
rejection of that piece.

9.3. Procedure for backfilling

1. Backfilling will be carried out in accordance with specification
2. Approved backfill material will be utilized to backfill the trench in 250mm layers, carefully compacted
by hand rammers up to a level of 600 mm above the crown of the pipe.
3. Subsequently, backfilling will continue in layers of 25cm compacted in the lower regions by mechanical
plate compactors and in the upper region by hand operated drum rollers.
4. Compaction test will be carried out for the backfilling, to a minimum Proctor density of 90% under
non-paved areas and 95% under roads and paved areas. In areas under roads backfilling compaction
tests will be carried out in accordance with the Abu Dhabi Municipality specification for backfilling of
trenches and excavation in tiles/paved parking and roads. The frequency of tests will be in accordance
with the requirements of the specification.
5. Backfilling will start immediately after the pipeline is tested and approved.
9.4. Procedure for concrete bed & surround for GRP pipes
1. All procedures method will be the same except for the following:
2. 100mm thick Class ‘C’ blinding concrete with hooks embedded to hold the pipes in position and level.
3. Concrete blocks for adjustment of pipe level placed at 3 Mtr. Intervals.
4. Concrete 20N/mm2 pipe surround with flexible joint at pipe joints.
5. Flexible sheet be provided at every joints.

9.5. Procedure for construction of chambers

1. Method Statement for Inspection of Chambers
2. Construction of these units shall be carried out in the following sequences details below and it shall be
understood throughout this method statement that every activity will be inspected and approved by
the engineer prior to the commencement of subsequent activity.
3. Shop Drawing: Proposed Location for Chambers will be surveyed based on approved drawings.
4. Preliminary setting out will be carried to assess the feasibility of filing the chambers.
5. Dewatering: Depending on the location of chamber and ground water presence, dewatering is
required, shall be carried out as per method statement.
6. Setting Out::Setting out of manhole shall be done as per the approved shop drawings, excavation will
be carried out along with the pipeline trenches.
7. Blinding: After obtaining the approval from Engineer for the formation level blinding concrete shall be
laid to a minimum of 100mm thick.
8. Base: Shutter will either be steel or wooden shutter (Marine Plywood).
9. Sufficient cement cover blocks shall be placed to maintain a 75mm clear concrete cover at the bottom
of base in case of reinforced chambers.
10. The Engineer shall inspect all formworks, reinforcement and water bar in wall kicker before placing the
concrete.
11. Approved concrete of 40N/mm2 shall be placed in accordance with the contract requirements and it
shall be well compacted with vibrators. Care will be taken not to entrap air underneath the
benching/liners.
12. Shuttering will be removed after concrete has gained sufficient strength to carry its own weight and
imposed loads. Curing of concrete will start after initial setting of concrete.
13. Wall: Construction of wall is done to the entire height of the wall in a single pour.
14. Internal & external shutter work will be carried out and proper support will be given to the shutter to
avoid any deformation.
15. The concrete cover slab will be constructed separately with respect to road levels.
16. Procedure for pouring concrete, de-shuttering and curing shall be the same as described in base
section above.
17. Protection of external concrete surfaces
18. External surfaces for concrete structures shall be protected with approved waterproofing membrane
system as per specification and our method statement of waterproofing.
19. Backfilling: Backfilling shall be done after the approval of waterproofing works and it shall be as per
specification and our method statement for backfilling.
20. Fixing the Cover & Frame: Frame and cover fixing shall be as per specification and our Method
statement for fixing D.I. Cover and Frame.
21. Internal finishing for drainage chambers will be with 7mm of GRP in-situ lamination in three layers.
22. Upper face of the benching will receive a non-slip finish of silica sand.

9.6. Procedure for construction of manholes

1500mm Manhole on 150, 200 and 300 G.R.P dia. Sewerage Lines up to 6m Depth
1. We propose to use a Pre-Fabricated 7mm thick one piece moulding formed precisely to suit the
required shape from approved GRP supplier manholes units as per standard details. Prior approval of
the manhole production schedule will be obtained.
2. Safety procedures will be adopted as described in the safety manual submitted and will generally
comply with the requirements and ADSSC safety manual.
3. All manholes shall have a circular base unit above which a circular shaft shall be constructed. The base
will be cast in a single part.
4. BASE: Upon receipt of the Engineer’s approval for the formation, concrete blinding to a thickness of
100mm will be poured and trowel finished to a top level 45cm below the top of benching of the
manhole. (Invert Level)
5. Base unit is fixed on line & level followed by shuttering benching is adequately loaded with sand bags
to avoid uplift during casting.
6. Approved concrete shall be placed in accordance with contract requirement.
7. Wall & Cover Slab: Wall construction is done to the entire height along with cover slab, with
preformed double skin liners used, from approved GRP supplier.
8. These double skin liners are used as concrete shutter during casting (with additional ring supports)
9. Lamination (Internal & External) shaft joints are laminated by qualified laminator.
10. 200mm thick concrete 40N/mm2; cover slab with 600 Dia circular opening will be as shown on plan
Contract Drawing.
11. D.I. Cover & Frame (Class D400/B125) as specified will be fixed to line & level as per road camber on
class C40 concrete.

9.7. Procedure for backdrop construction

1. The backdrop lower connection to manhole shall be fixed and cast along with the manhole base.
2. While casting manhole shaft, a plywood box frame shall be fixed at the backdrop upper connection
level.
3. Backdrop construction shall start after finishing shaft construction; as per the following steps:
4. An opening in the shaft GRP liner, with a size as per backdrop pipe size shall be prepared at the
backdrop higher connection point.
5. The backdrop pipe shall be fixed and connected, by lamination.
6. Due to practicality, back drop concrete is done after shaft.
7. Shutter shall be fixed around the pipe as per the required size and concrete will be poured.

9.7.1. Material approved for backdrop construction

1. UPVC pipes and fittings (1 Elbow and 1 Tee required) used shall be from approved supplier.
2. In some cases GRP Tee and Elbow may be required which will be obtained from approved supplier
3. Concrete shall be from approved batching plant
4. Lamination material from GRP Factory.

9.8. Procedure for reinforcement works

1. Reinforcing bars to be used shall be from approved Manufacturers/Suppliers.
2. IFC drawings for structures (steel reinforcement) shall be used for construction typical.
3. After obtaining the approval, the steel reinforcement will be cut to the required length and then bent
to the required shape as per approved bar bending schedule.
4. The reinforcement steel shall be fixed as per the latest approved shop drawing.

9.8.1. Machineries and tools required for reinforcement works

1. Mobile Crane
2. Cutting Machine
3. Bending Machine
4. Pincers
5. Protective Instruments: Hand Gloves, Eye Glasses, Helmets
6. Steel Brush

9.9. Procedure for waterproofing works

1. Waterproofing material to be used shall be as per approved material submittal.
2. After the required curing time for the structure finishes, concreter surface shall be cleaned from any
dust, oil or any other material that will prevent the adhesion between concrete and the base
waterproofing material.
3. All external corners are to be chamfered and angle fillets formed with sand cement mixture are
provided to all internal corners to prevent a 90º bend to the water proofing membrane.
4. A single coat of primer shall be applied as per manufacturer’s recommendation. The primer is to
applied evenly on the subsurface using a roller or brush. The primer shall be allowed to dry until ‘tack-
free’.
5. The Consultant shall check the application of primer prior to proceed with the installation of the
waterproofing membrane.
6. After the approval is obtained, one layer of waterproofing membrane shall be applied to the ‘tack-free’
primed concrete surface; all membrane corners, overlaps and angles shall fully torched. Any void or
air gap must be corrected if found, by cutting, opening, patching with 150mm overlaps each side of
cut.
7. The membrane shall be fully bonded to the subgrade, by torching evenly forming 100mm side laps and
150mm end laps. All side end laps shall be fully bonded by torching so that a bead of molten bitumen
appears at the seam. This bead shall be smoothened using a round trip trowel.
8. The Consultant shall check the waterproofing membrane and shall be approved prior to proceed with
the membrane protection system.
9. After the approval is obtained, protection sheet shall be fixed on vertical sides. Overlapping between
protection sheets shall be 150mm as per specification. RFIA will be raised for Consultant′s approval.

9.9.1. Approved material for water proofing works

1. Concrete – Primer (from approved membrane source)
2. Waterproofing membrane from approved source.

9.9.2. Tools required for water proofing works

1. Gas torch (for membrane)
2. Gas cylinder with regulator and associated hose pipe (for membrane)
3. Trowel with round tip (for membrane)
4. Measuring tape (for membrane & protection board)
5. Rooter’s knife (for membrane)
6. Protective safety tools, i.e. hand gloves, helmets, shoes
7. Paint roller & paint brush (for primer)
8. Plastic Bucket (for primer & plastic screed)
9. Ladder
10. Saw (for protection board)
11. Hand shovel (for protective screed)
 9.10. Procedure for fixing DI cover & frame
1. Before fixing the DI Frame, surface of cover slab shall be chipped a cleaned; water proofing membrane
shall be properly terminated on top edge of slab. Also covers and frames must be coated before
fixing.
2. DI frame shall be installed as per the required level on cement blocks at the corners, which is 10cm by
10cm in width and depth respectively, while length shall be determined as per site requirements. GRP
liner edge shall be flush with internal face of the frame.
3. Plywood shutter shall be fixed inside at the internal face of the frame.
4. Proper external shutter as per the required dia. and height shall be fixed at the external side of the
frame, with proper chamfering.
5. Concrete is to be poured to surround the DI Frame at the top of the cover slab. The top surface of
concrete shall be smoothly finished.
6. Curing shall be made to the period required by specifications.
7. The plywood shutter which was fixed inside the frame shall be removed and the inner face shall be
prepared for lamination of a min. of 7mm
8. The outer face of concrete shall be painted with two coats of the approved bituminous paint.
9. GRP ceiling plate shall be fixed with EPDM rubber gasket and DI cover shall be fixed.

9.10.1. Tools required for fixing DI cover and frames

1. Hilti Drill / Mixer / Breaker
2. Steel Trowel
3. Plastic Bucket
4. Protective Instruments; Hand Gloves, Eye Glasses, Helmet
5. Mason Hammer
6. Chisel

9.11. Procedure for GRP manhole liners

Site Joint Lamination as per approved subcontractor method statement detailed below
1. All Surface to be joined should be clean dry and well abraded by grinder with 36 or 50 grade Sand Disc
and a flexible backing pad should be used, all the resin rich surfaces should be grinded to expose the
fibre so that the first layer of the in-situ lamination to be glass to glass. The minimum wide should be
100mm.
2. The humidity level should be considered and it should be below 75% when the site lamination is
carried out.
3. Prepare the 450g/m2 E glass (Advantex) CSM and ‘C’ glass veil surface tissue in minimum of 100mm
wide strips. The number of layers required for different lamination location is shown on the attached
sketch (7 layers).
4. Mix Catalyst (1 to 2% by weight) to the pre-accelerated resins (Vinyl ester and Isophthalic specified in
the sketch) in a bowl. Catalyst should be measured using a Catalyst dispenser. The percentage of
Catalyst shall vary according to the temperature the percentage of Catalyst should be less. The bowl
used should be clean and dry.
5. Apply a cost of Isophthalic (Vinyl ester) resin to the abraded surface with dacom roller or brush.
6. Position the first layer of 450g/m2 C.S.M. directly on top of the resin and apply another coat of resin.
7. Consolidate the CSM by rolling with 2inch to 4inch metal roller to expel all entrapped air in it.
8. Continue this procedure until all the required layers of CSM (450) are positioned in place.
9. Position the layer of ‘C’ glass veil surface tissue over the final layer of CSM with Vinyl ester Resin and
roll out all entrapped air until a resin rich surface is obtained.
 10. The liner layer shall comprise one layer of glass surface veil 450gm/m2 and two layers of CSM
300gm/m2, ‘Advantex’ powder bounded corrosion resistance or any other equivalent approved type,
impregnated with Vinyl ester resin of approved type with a glass resin ratio of 25:75 and a tolerance of
+/- 5%.
11. The structural layer shall comprise of six layer of chopped strand mat 450gm/m2 ‘Advantex’ powder
bounded corrosion resistance or equivalent approved type, impregnated with Isophthalic resin of
approved type and 0.5mm flow coat on the external surface with resin of approved type with a
minimum glass resin ratio of 70:30
12. Wash all the tools (metal rollers, brush, etc.) with acetone before the resin sets.
13. Wait until it is cured.
14. Apply a Vinyl ester flow coat with paraffin wax and after it is cured, all shall be cleaned and puffered
properly.

9.11.1. Material required for site GRP lamination

1. Surface tissue ‘C’ glass
2. 300gm CSM ECR glass
3. 450gm CSM ECR glass
4. Pre-accelerated Vinyl ester Resin
5. Isophthalic Resin
6. Catalyst
7. Flow Coat
8. Filler Paste (if necessary)
9. Acetone
10. Empty Plastic Bucket
11. Steel Roller 4” in length for Releasing the Trapped air
12. 3” Wide Brush for cleaning the surface with Acetone
13. 4” Paint roller for applying the Resin
14. Metal pot to carry the Acetone on site.

10. STORAGE REQUIREMENT

1. Pre-accelerated resin, catalyst flow coat and filler pasted should be stored at a temperature below 20
Cº
2. Surface tissue and CSM should be kept at a non humid place
3. The Pre-accelerated resin has only one month shelf life.

11. HEALTH, SAFETY AND ENVIRONMENT

12. ATTACHMENTS
12.1. Inspection Checklists
12.2. Inspection Test Plan
12.3. Risk Assessment
12.4. Technical Data sheet (TDS)