Method Statement for Manhole Construction (Cast In Situ Stormwater Manholes)

CONTENTS

1. Scope of Work

• Definitions

• References

• Subcontractors

• Materials

• Plant  & Equipment

• Safety

• Prior Activities

• Procedure

1. Responsibilities

1. Attachments

1. Scope:

1.1	This Method Statement covers the cast in situ concrete storm water manholes, single and double catch pit Type (I), (II), and (III).

2. Definitions:

2.1	MS: Storm Water Drainage Method Statement
2.2	ITR : Inspection and Testing Request
2.3	PPS :  Particular Project Specification
2.4	GPS :  General Project  Specification
2.5	UG :  Underground
2.6	TPS :  Technical  Project Specification

3. References:

3.1   3.2   3.3   3.4   3.5   3.6   3.7   3.8   3.9   3.10

GPS:      Section 401  : Clause 401.13 Formworks   GPS:      Section 401  : Clause 401.3 and 401.14 Concrete Reinforcement   GPS:      Section 401: Clause 401.7and 401.12 Cast –in-place Concrete   GPS:      Section 401: Clause 401.9 Quality control.   TPS:       Section 901: Clause 901.4.7 Construction manholes and chambers.   TPS:        Section 901: Clause 901.4.7: Formwork.   MS :         STM-1004 Dewatering   MS :         STM-1005 Surveying   MS :         STM-1002 Earthworks   MS :         STM-1009  GRP pipe Laying

4. Subcontractors:

None

5.  Products:

5.1   5.2   5.3   5.4   5.5   5.6   5.7   5.8

Shutter.   Waterproofing membrane of approved source.   Protection board of approved source.   Epoxy paint of approved source.   Steel Reinforcement   Class” 40/20/S for blinding and 50/20/R “Concrete.   Cover & Frame   Access ladder rings.

6. Tools & Equipments:

6.1	De watering Equipment
6.2 6.3 6.4 6.5 6.6 6.7 6.8 6.9 6.10 6.11 6.12 6.13 6.14 6.15 6.16 6.17 6.18	Excavators Front End Loader (Shovel) Tipper Trucks Mobile Crane Flat- bed truck and trailer. Concrete Trucks Light Vehicles Compactor (Plat or Roller) Concrete Vibrators Surveying Instruments Nylon lifting slings Ladders Concrete Barricades Flagging Tape/Warning Tape Concrete Form work Concrete Temp. Gauge Slump cone, cube moulds.

 7. Safety

7.1	GPS Section 102: Clause 102.11, 102.12 and 102.14 General and Preliminary.
7.2	TPS    Technical Project Specification Section 901 Clues 901.3: Trench Excavation and Backfill.
7.3   7.4   7.5   7.6   a).       b).                 c).               d)	PPS Section 100: Clause 100.2Airport Emergency And Safety   CSM   : Construction Safety Manual   OAJ JV: Safety Manual.   Safety Hazards and Precautions   Strike UG Services:   Use locator and hand excavation  (trial holes)   Excavation Collapse:   Batter sides to sage slope or provide shoring (as directed by geotechnical consultant) and subject to Engineer’s approval.   Keep vehicles/equipment safety away from excavation edge.   Keep spoil at least 2.0 meter away from edge. Fall into Excavation   Provide fencing, guardrails of flagging tape around edges and night lights.   Provide safely fixed ladders(every 50m)   Provide banks man when operating equipment near excavation.   Crane Accidents   All cranes checked and certified.   Operators professional and well experienced   Provide banks man when operating near excavation.   Check load indicator, slings and wire ropes daily.
e).	Falling Objects:   Stand clear during lifting operations   Wear Hard Hats
f).	Equipment & Vehicles:   Use Safety Belts   Slow down and obey speed limits.   Provide banks man when operating equipment near excavation.
g).	Confined Space   Check air in deep narrow trenches or excavation before entry.   Check excavations for snakes and scorpions before entry.   Take precautions against flooding.   Develop rescue procedure.

8. Prior Activities:

8.1	Prepare Shop Drawings.
8.2	Check for Existing Utilities before Excavation (Trial Holes) according to MS-1012
8.3	Proper discharge away from work area will be provided.  Permits will be obtained where needed.

 9. Procedure:

All excavation and filling will be carried out to comply with the requirements of OAJ-JV Inspection test Plan which in turn reflects the testing requirements of the Contract.

9.1   9.2   9.3   Note:     9.4     Note:     9.5     9.6     9.7         9.8       9.9       Note:       9.10           9.11       9.12       9.13   9.14       9.15     Note:     9.16     Note:     9.17   9.18     9.19     9.20         9.21           9.22           10.1       10.2         10.3           11.1   11.2   11.3   11.4   11.5

Survey will be conducted according to MS -1005   De watering (if necessary)  will be conducted according to MS -1004   Excavation will be conducted to the proper formation level according to MS -1008   The Consultants Inspector will be notified if any areas are over excavated or unsuitable materials are encountered.   The soil at the formation level will be compacted to 98% of its MDD, or to the bearing capacity verified.   Formation compaction is a Hold Point and will be confirmed by the Engineer’s Inspector before proceeding with blinding concrete.   After formation compaction is confirmed and compliant with the specs, blinding concrete will be placed as shown on the drawings.   The formation level will be to the required lines and grades as detailed in the approved technical data   The actual location of the manhole might have a tolerable difference from the theoretical location. A shop drawing will be issued for each section of line depicting proposed locations for the manholes. This shop drawing will be submitted for the Engineer’s approval. Short pipes will be cast along with the Manholes.   Shutter for base slab will be erected and supported. Kicker and recess for joint sealant will be allowed for all through the top of kicker and around the pipe. The kicker height will be 15 cm.   The reinforcement steel for the base will be cut and bent as per the approved bar bending schedule, then it will be fixed on site over 75mm concrete spacers to allow for cover.   For details refer to attached Shop Drawing No PGAD 745/1008/C/928 REV (A), /9029, and 931. Steel fabrication is a Hold Point. It should be checked and approved by the Consultant prior to concrete.   Once all pre-pour aspects are checked and found acceptable by the Engineer, concrete Grade: (40/20/S and 50/20/R) will be poured. At least 2 vibrators with 50mm poker (and 1 stand-by) would be available prior and while concreting. Concrete will be carefully placed in horizontal layers not exceeding 500mm which shall be kept at an even height throughout the work.   Concrete shall be carried out continuously to construction joints. It shall be poured in its final position directly. Maximum height to pour shall not exceed 2.0m to avoid segregation and separation of the constituent materials.   As soon as is practicable, all concrete shall be cured by the application of approved concrete curing compound and/or covered with polythene sheet or other approved material for a period of 7 days.   Form work will be struck off as per periods mentioned in the Specifications.   The wall will be cast in 1st stage to 500mm above crown of pipe. The internal shutter will be fixed, steel erected and inspected, after which the outer shutter will be erected, tightened and supported. Sealant will be fixed along the pipe perimeter.   Once all pre-pour aspects are checked and found acceptable by the Consultant, concreting shall proceed.   Immediately before placing of new concrete, all foreign matters shall be thoroughly cleaned away and the surface moistened.   For concreting, curing, striking of shutter, the steps detailed under 9.12 and 9.13 shall be followed.   Utmost care will be taken for well Compacting the concrete below the pipe and at the acute angles.   After dismantling the wall 1st stage shutters, other stages (as required) will follow .   Roof slab (cast in situ or pre cast) and beams will be carried out as per the approved shop drawings.    After dismantling the internal slab shutter, the manhole will be cleaned from inside. Ladders (where required) will then be fixed.   Before proceeding with back filling, the grooves all through the joints around the pipes will be cleaned and filled with approved Joint Sealant. After drying, primer for tanking will be applied on external faces, water proofing membrane fixed then protected with approved protection board.   Internal Concrete faces will be treated and coated with approved Epoxy Coating System. The steps of surface preparation and Coating application will be forwarded to the Engineer along with the Material Submittal for the intended Epoxy Coating System     Frame and cover will be erected as specified refer shop drawing (PGAD 745/1008/C/928 REV (A) and /929 REV (A)). Backfilling can then proceed according to MS-1008.   10.Responsiblilities:   It is the Construction manager’s duty to ensure that all necessary safety and protective equipment are provided along with properly trained and qualified personnel.   It is the Site Supervisor’s duty to organize the work in a safe manner and to ensure that safety and protective equipment are being properly utilized. He must also assure the method statement procedure is followed and must observe the hold –points and notify the Consultant for inspection.   It is the worker’s duty to properly wear the protective equipment provided and obey all safety rules. He must also perform the work as described in the method statement procedure.   11.Attachments:   Contract Drawing PGAD 745/1008/C/928 REV (A)   Contract Drawing PGAD 745/1008/C/929 REV (A)   Contract Drawing PGAD 745/1008/C/960 REV (A)   Contract Drawing PGAD 745/1008/C/961 REV (A)   Contract Drawing PGAD 745/1008/C/962 REV (A)