Storm Drainage Water Piping Network Method Statement

TABLE OF CONTENTS

1. REVISION RECORD

2. PURPOSE

3. SCOPE OF WORKS

4. REFERENCES

4.1. Contract documents

4.2. Contractors Submittal

5. DEFINITIONS / ABBREVIATIONS

5.1. Definition

5.2. Abbreviations

6. RESPONSIBILITIES

6.1. Project Manager

6.2. Site Engineer

6.3. Project Engineer

6.4. QA/QC Engineer / Inspector

6.5. Surveyor

6.6. HSE Engineer/Officer

6.7. Foremen/ Works Supervisor

7. EQUIPMENTS/ TOOLS / MANPOWER/MATERIALS

7.1. List of Equipment’s/Tools (To be used as per requirement)

7.2. List of Manpower

7.3. List of Materials

8. PROCEDURE

8.1. General Procedural Matters

8.2. Dewatering

8.3. Where rock is encountered

8.4. Notes on excavation

8.5. PIPE LYING – GRP PIPE (GRAVEL SURROUND)

8.6. Backfilling

8.7. PIPE LYING – UPVC PIPES (GRAVEL SURROUND)

8.8. Method Statement of Concrete Bed & Surround for  G.R.P., uPVC  Pipes

8.9. Procedure for water Test for G.R.P., uPVC Pipes

8.10. Procedure for the storage & Handling of Pipes

8.11. Procedure for Backfilling

8.12. Procedure for New Port at Existing Storm Manhole

8.13. Procedure for Inspection of Chambers

8.14. Procedure for Fixing the cover & frame

8.15. 1500 mm Dia Manhole on 200-500 Dia Surface  Lines up to 6m Depth

8.16. 2000 mm Dia Manhole on 600-900 and Dia Surface water Lines (Depth>6.0M.)

9. HEALTH, SAFETY AND ENVIRONMENT

10. ATTACHMENTS

10.1. Inspection Checklists

10.2. Inspection & Testing Plan ITP

10.3. Risk Assessment

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 All previous revisions are hereby superseded and are to be destroyed.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 Number Revision Date Prepared by Checked by
Reviewed By Construction Manager Technical Manager QA/QC Engineer HSE Officer MEP Coordinator Sub-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 line Storm water in accordance with the requirements specified in the relevant specifications, procedures and drawings, considering safety and quality of the work activities.

3. SCOPE OF WORKS

General procedural matters

Dewatering

Notes on excavation

Pipe laying, testing, storing, backfilling, cone pipe surround & port construction

Construction of chamber, catch basins & manholes

4. REFERENCES

Contract documents

Project Specifications

Contract Drawings

Contractors Submittals

Project Quality Plan

Project Safety Plan

Material approvals

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

Shop Drawings

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

Related method Statements

Sr. No. Description Method No. Rev No. Date Remarks
1          
2          
3          

 

5. DEFINITIONS / ABBREVIATIONS

Definitions

Project –

Client –

Developer –

Consultant –

PMC –

Contractor –

Sub-contractor –

Supplier –

Abbreviations

Engineer – Representative of  engineering consultancy

SSC – Sewage Services Company

ICL- Inspection Check List

IR – Inspection Request

ITL-Independent Testing Laboratory

ITP – Inspection and Test Plan

ITR -Inspection & Test Requests

MAT – Material Submittal

MEP – Mechanical Electrical Plumbing

MET – Method Statement

MIR- Material Inspection Request

MSDS – Material Safety Data Sheet

PPE -Personal Protective Equipment

PQP -Project Quality Plan

PTW -Permit To Work ( Working at Height or enclosed spaces)

HIRA -Hazard Identification and Risk Assessment

RFIA – Request for Inspection and Approval

SPD – Shop Drawing

TBM – Temporary Bench Mark

6. RESPONSIBILITIES

Project Manager

Ensuring that the subject works in coordination with other works with the requirements of Quality Plan & program.

Ensuring the full compliance of subcontractors with Company Quality policies and with the requirements of this method statement.

To ensure that all the equipment required to execute the works according to the construction program are available, in good condition, and provide any additional equipment that might be required.

To co-ordinate with the Construction Manager, Project Engineer, Safety Engineer, Foreman and Surveyor for a safe and proper execution of the works.

To guide specific attention to all measures in coordination with the safety Officer/Engineer.

Site Engineer

Ensure area is ready and safe to start the works.

Arrange for required Plant manpower & Equipment’s in arrangement with Project Engineer / Site Foreman.

Liaise and co-ordinate with the Project Manager to execute the works as per approved drawings.

Co – ordinate with Safety Officer to maintain safe working & proper housekeeping of site all time.

Project Engineer

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.

To be aware of test frequencies related to the activities.

To control disposal of waste excavated material according to the instructions received from the Project Manager.

To inform the QC Inspector of the areas ready for inspection and to prepare the RFIA with complete attachments.

QA/QC Engineer / Inspector

Ensuring that Consultant/Client inspection requests are implemented.

Compilation of all necessary quality control checklists

Assisting Consultants during the Inspections.

The control of work performance by means of checking the work before consultants’ inspection and issuing RFIAs & punch lists as necessary.

Completion of documentation to verify the work performed.

Controlling all inspection activities on-site in line with ITPs.

Ensuring that all test equipment including surveying equipment is calibrated and is suitable for use on-site.

Surveyor

To establish benchmarks from agreed reference points, provide required setting out and level markings and follow up with regular checks.

Co-ordinate with the Site Engineer / Foreman and ensure the approved shop drawings/construction drawings will be implemented properly.

Maintain survey details and reports, periodically check the progressing works and advise the Project Manager of any deviation from the drawings.

HSE Engineer/Officer

To have latest revision of drawing on site all times.

To ensure implementation of all safety measures related to the nature of works being carried out, and in accordance with the Project Safety Plan.

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.

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.

To maintain continuous inspections of the site activities, advise and train persons on a daily basis to prevent accidents and personnel injury.

To give special concern to housekeeping, and ensure that the site is maintained clean and tidy.

To ensure all the relevant safety sign boards for different works are in place.

Foremen/ Works Supervisor

Ensure the works are progressed in the sequence as agreed with the Site Engineer.

Ensure ready mix concrete ordered from the approved supplier is delivered on time and with sufficient quantity for continuous casting of the planned pour.

Liaise with the Project / Site Manager for the allocation of the work force, ensuring adequate manpower is available.

Liaise with the site manager to ensure all the required plant / materials are available to construct the works.

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

List of Equipment’s/Tools (To be used as per requirement)

Mobile Crane

C.B

Excavators

Roller Compactors (Double Drum)

Wheel LoadersStorm Drainage Piping & Sanitary Vent Installation Method Statement

De – watering Pumps & Accessories

Plate compactors

Generator welding Machine

Concrete Pumps

Scabbling /Chipping Gun

Masonry tools

Concrete Buckets

Survey Equipment’s (Calibrated)

Crow Bar

D Shackles

Nylon Slings

Carpenter Tools

Masonry Tools

Welding Tools

Tanking Tools

De Watering Tools

Mechanic Tools

Chipping Hammer

Hilti Drill

Jig Saw

Pressure Pump

List of Manpower

Project Manager

Project Engineer

Site Engineer

QA/QC Engineers/ Inspectors

Safety Engineer/Officers

Lab Technician

Surveyors

Foremen/Work Supervisors

Charge Hands

Equipment Operators

Skilled and unskilled laborer’s

List of Materials

Ready mix concrete with approved design & trial mix of Class B

Reinforcement Steel Bars, Assorted sizes, Please refer to approved shop drawings

18mm thick Phenolic Board (Plywood)

Assorted Wood

Assorted Nails and Concrete spacer

Tie Rods and Steel Clamps

Cup-Lock with Steel Decking and Infill System,

3/8” Aggregates(natural)

Polyethylene sheets, Absorptive Mats and Water

Poly Release WB Mould/Shutter Release Agent.

Note:  Quantity of manpower, equipment and materials will be submitted on the daily progress report.

8. PROCEDURE OF STORM DRAINAGE INSTALLATION

8.1 General Procedural Matters

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.

Any obstruction observed during site inspection will be recorded and photographed and confirmed in writing for reference and records.

Following the issuance of the notices of intent to all the concerned authorities, we shall liaise with the Engineer and the Municipality to accurately record the conditions of existing manholes, wherever necessary (for connection to existing system).

Based on received approved drawings from the various authorities in response to our notices of intent, we shall carefully excavate a series of trial holes with a view to locate the exact position of the services.

Shop drawing for each line will be prepared and approved by Engineer prior to start the actual work.

Work will proceed in the event the proposed sewer is unaffected by obstruction.

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.

Prior to dewatering, necessary approval will be obtained from the concerned authorities prior to discharge in existing system.

8.2 Dewatering

Where formation levels are below the ground water table, we propose to dewater our excavation utilizing well point dewatering system.

We shall pre-drill the wells using Drill head fitted to the boom of a wheeled or chain excavator.

The well-points of 6 m. in length will be installed into the pre-drilled holes using jetting pumps.

The slotted filter heads of the well-points will be surrounded with sharp filter sand while jetting.

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.

8.3 Where rock is encountered

A well point dewatering system will be installed approximately for the first 30 metre length, in order to establish a sump, from where the ground water will be sumped 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.

8.4 Notes on excavation

The Existing ground level will be recorded.

Excavation will proceed after successful dewatering wherever required.

As trunk 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.

The deep excavation will be in stages as per depth band.

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.

Due care will be taken to maintain and support all the existing services and structures.

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.

Diversions will be carried out by safety barriers.

Access ladders or scaffolding staircase will be provided for ease of entry and exit from the excavations every 25m.

Inspection requests, will be given to the Engineer/Inspectors,  for obtaining approvals at various stages

The available bore whole results have due sign face upon the method of excavation and dewatering for a particular area.

The excavated material will be moved to a safe distance from the trench sides.

Adequate shoring, battering of excavation sides will be undertaken to ensure the trench remains stable & safe working environment.

8.5 STORM DRAINAGE PIPE LYING – GRP PIPE (GRAVEL SURROUND):

Drawing shall be re-viewed 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.

Written inspection requests will be given to the Engineer/Inspectors for approval of various stages of work, such as –

  • Setting out
  • Excavation & formation
  • Side and above bedding
  • Pipe Laying (Alignment & Levels)
  • Water Test
  • Deflection Test (Ball test)

8.6 Backfilling

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).

The bedding material 150 mm depth increased to 300 in unstable grounds a directed by the Engineer 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.

The stacked pipes will be lowered carefully in to the trench and laid downstream to upstream.

GRP Pipes will be laid in granular bed and surrounded by 10mm single size crushed aggregate, contained within approved geotextile trench lining material, to have an overlap of 300 mm.

The GRP pipes for Dia above 500 will be joined by means of using turgor.

The pipe will be checked for line and level jointly by our Surveyor and the Engineer’s inspector.

Each pipe joint will be enclosed with approved PVC wrapping tape.

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.

Following this, the pipe surround material will be placed carefully in the same manner, to a level of 30 cm in two layers above the crown of the pipe and compacted. The Geo-textile Fabric overlap will be 30cm.

Selected materials previously excavated from the trench will be utilized to backfill the trench in 250 mm layers, carefully compacted by hand rammers , up to level of 600 mm above the crown of the pipe.

Water test in accordance with specification will be carried out as per the attached method statement.

When pipe lying is not in progress, we will ensure that the pipe ends are closed at all times by water-tight plugs.

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.

Deflection test will be carried out immediately after 100% backfilled (to allowable limit).

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  Municipality specification for backfilling of Trenches and Excavation in Tiled/Paved Parking’s and Roads.

150mm wide service warning tape will be placed 800mm below the finished ground level.

PIPE LYING – UPVC STORM DRAINAGE PIPES (GRAVEL SURROUND):

As Drawing shall be re-viewed by the Project Engineer & communicated to foreman in charge of pipe lying. UPVC pipes will be laid in accordance with the manufacturer’s instructions concerning the laying of pipes and bedding for the same, as submitted for approval.

Written inspection requests will be given to the Engineer/Inspectors for approval of various stages of work, such as

  • Setting out
  • Excavation & formation
  • Side and above bedding
  • Pipe Laying (Alignment & Levels)
  • Water Test
  • Deflection Test (Ball test)

Backfilling.

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).

The 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.

The stacked pipes will be lowered by downstream to upstream.

UPVC Pipes will be laid in granular bed and surrounded by 10mm single size natural aggregate, contained within approved geotextile trench lining material.

The pipe will be checked for line and level jointly by our Surveyor and the Engineer’s inspector.

Each pipe joint will be enclosed with approved PVC wrapping tape.

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 using 2 hand compactors, simultaneously on either side of the pipe to impart symmetrical compaction.

Following this, the pipe surround material will be placed carefully in the same manner, to a level of 30 cm in two layers above the crown of the pipe and compacted. The Geo-textile Fabric overlap will be 30cm.

Selected materials previously excavated from the trench will be utilized to backfill the trench in 250 mm layers, carefully compacted by hand rammers , up to level of 600 mm above the crown of the pipe.

Water test in accordance with specification will be carried out as per the attached method statement.

When pipe lying is not in progress, we will ensure that the pipe ends are closed at all times by water-tight plugs.

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.

Upon completion of the backfilling, the 1st Pig test will be carried out (allowable limit: 3%), for uPVC Pipe & Deflection test for G.R.P Pipes

A 2nd Pig test will be carried out immediately prior to issue of the P.A.C (allowable limit: 5%), for uPVC Pipe & Deflection test for G.R.P Pipes.

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  Municipality specification for backfilling of Trenches and Excavation in Tiled/Paved Parking’s and Roads.

A final mirror test is carried out to ascertain the alignment.

150 mm wide service warning tape will be placed 800 mm below the finished ground level.

8.8 Method Statement of Concrete Bed & Surround for R.P., uPVC  Pipes

All procedures methods will be the same except for the following.

50 cm thick class c blinding concrete with hooks embedded to hold the pipes in position & level.

Concrete blocks for adjustment of pipe level placed at 3 meters intervals.

Concrete class C pipe surround O + 300 with flexible joint at pipe joints.

8.9 Procedure for water Test for G.R.P., uPVC Pipes

Complete the granular bedding up to the soffit of the pipeline.

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.’

Fill the line from downstream pipe (Filling pipe)

Keep the Air Release Pipe open to release the air.

When water starts coming from the Air Release Pipe, the pipe will be closed.

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.

Measure the head at the down steam end.

The pressure will be maintained for a period of 30 minutes.

If there is any drop in pressure, water will be added from a measuring vessel at 10 minutes intervals.

A record will be kept of the quantity of water added.

The added quantity of water should not exceed 1 liter per day per millimeter of nominal internal diameter, per kilometer of pipe.

Pipelines will be tested in length between manholes to manhole.

8.10 Procedure for the storage & Handling of Pipes

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.

It will be ensured that the Pipes and fittings do not come into contact with sharp projections.

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.

The pipes will be stacked in such a manner so that the height of the stacked pipes does not exceed 2 meters.

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.

Rubber Joint Rings will be stored in an air-conditioned store.

Only nylon slings shall be used for lifting pipes and units (Transportation / Installation)

Segregation of damaged products (if any) is brought to the notice of Engineer for either repair or rejection of that piece.

8.11 Procedure for Backfilling

Backfilling will be carried out in accordance with specification

Selected material previously excavated from the trench in 150 mm layers, carefully compacted by hand rammers up to a level of 600 mm above the crown of the pipe.

Subsequently, backfilling will continue in layers of 30 cm, compacted in the lower regions by mechanical plate compactors and in the upper region by hand operated drum rollers.

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 local 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.

Backfilling will start immediately after the pipeline is tested and approved.

The Marking Tape will be laid 50 cm from the finished ground level.

8.12 Procedure for New Port at Existing Storm Manhole.

After completion of open cut excavation for the portion between existing manhole and proposed manhole/chamber, the location will be exposed and marked on the external face of existing manhole wall.

Relevant authority shall be notified, before any activity in manhole to ensure condition of the down storm flow is in continuous operation to avoid any backflow and maintain normal flow to enable to carry out the respective works in sequence.

Cutting of existing manhole wall protection for the marked location will be carried out prior to breaking of concrete will be preceded by using small electrical hammer till reaching the internal face of manhole wall.

The GRP new port will be installed inside the cut portion as per the required level and alignment.

Grouting will be done surround the new port by using the approved grouting materials.

Once the curing time of grouting is completed, the protection for the disturbed portions (External and Internal) will be rectified as existing.

The outer connection from the proposed manhole/chamber to the newly constructed port will be done and encased by Concrete/Gravel Bed and surround.

Backfilling for the laid line and the exposed part around the existing manhole will be carried out on layers as specified.

8.13 Procedure for Inspection of Chambers

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.

Pre-cast Yard: Proposal for establishing a pre-cast yard will be submitted with location & the yard’s area

Shop Drawings:

  • Proposed Location for Chambers will be surveyed based on approved drawings.
  • Preliminary setting out will be carried to assess the feasibility of filing the chambers.
  • Shop drawing are attached include plan view, arrangement for base wall and roof slab.

Dewatering: Depending on the location of chamber and ground water presence, dewatering is required, shall be carried out as per method statement.

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.

Base: Shutter will either be steel or wooden shutter (Marine Plywood).

Steel reinforcement shall be fixed and placed where required according to the drawing.

  • Sufficient cement cover blocks shall be placed to maintain a 75mm clear concrete cover at the bottom of base in case of reinforced chambers.
  • The Engineer shall inspect all formworks, reinforcement and water bar in wall kicker before placing the concrete.
  • A Polypropylene formworks liner will be provided to the surfaces of the formwork to improve the finished surface of the concrete.
  • Approved concrete of 40N/mm2 shall be placed in accordance with the contract requirements and it shall be well compacted with vibrating pokers.
  • 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.

Wall & Cover Slab:

  • Construction of wall will be done to the entire height of the wall in a single pour.
  • Internal & external shutter work will be carried out and proper support will be given to the shutter to avoid any deformation.
  • The concrete cover slab will be constructed separately with respect to road levels.
  • Procedure for pouring concrete, de-shuttering and curing shall be the same as described in base section above.
  • Blinding:
  • After obtaining the approval from Engineer for the formation level blinding concrete shall be laid to a minimum of 75 mm thick.

8.14 Procedure for Fixing the cover & frame

Frame and cover fixing shall be as per specification and our Method statement for fixing D.I. Cover and Frame.

Internal finishing for drainage manhole will be approved epoxy paint as per specification.

8.15 1500 mm Dia Manhole on 200-500 Dia Surface Lines up to 6m Depth:

Use precast manhole unit as per standard details approved with internal coating and to use tanning externally for concrete protection.

Safety procedures will be adopted as described in the safety manual submitted and will generally comply with the requirements.

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.

Upon receipt of the Engineer’s approval for the formation, concrete blinding to depth of 50 mm will be poured and trowel finished to a top level 55 mm below the invert of the manhole. Prior approval of the Manhole production schedule will be obtained.

The ‘torch-applied’ water-proofing Membrane (5mm) will be placed in accordance with the manufacturer’s instructions.

The membrane will be protected with 50 mm screed.

Pre-Cast base pre painted is fixed on line & level followed by shafts, adjustments rings cover slabs

Fixing procedure is maintained by fixing 2 no. Gasket strips of 20 mm with between each joint. As detail 1 of drawing

250 mm thick removable concrete class b cover slab with 600 O circular opening will be (eccentric) as shown on plan.

Cover & Frame (class D400/B125) as specified will be fixed to line & level as per road camber by block work.

8.16 2000 mm Dia Manhole on 600-900 and Dia Surface water Lines (Depth>6.0M.):

The method for the construction of the manhole will be identical to that described in Method Statement expect for the SA, base to be casted on site. (App 20 T)

Upon completion of screed, the steel reinforcement for the base unit will be cut, bent and assembled at the steel yard as per Contract Drawings as well as the Bar Bending Schedules. It will then be brought to the site and with the help of a crane, placed above the concrete spacers between the screed and the steel cage.

Upon receipt of the Engineer’s approval for the steel reinforcement, the base top circular plywood will be positioned above the reinforcement using spaces between the steel and plywood.

The prevention of uplift during concreting will be ensured by placing a sufficient number of sand bags and tying the lifting hooks to plywood.

After placing the external shutters and having the same checked and approved by the Engineer, rest will be as per method statement, except that the first lift of shaft will be of 2000 mm Dia including the reducer slab, both of which will be concreted separately and the reducer slab will have reinforcement.

The manhole construction detail for 2000 mm dia.

A detailed sketches showing the construction details are explanatory.

9. HEALTH, SAFETY AND ENVIRONMENT

10. ATTACHMENTS

10.1 Inspection Checklists

10.2 Inspection Test Plan

10.3 Risk Assessment

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