Method Statement for Protection of Existing Gas Pipelines Using Precast Concrete Slabs

CONTENTS

1. Purpose

• Scope of Work

• Definitions

• References

• Materials

• Plant  & Equipment

• Safety

• Prior Activities

• Procedure

1. Responsibilities

1. Attachments

1.0      Purpose

1. To ensure that the protection of existing gas pipelines using precast concrete slabs, and related activities are executed safely and in accordance with the contract requirements and that all quality assurance / control activities are conducted in a systematic manner, works are inspected and conformance is verified and documented.

2.0      Scope of Work

• This procedure is applicable to the following works associated with the project titled, “New 2k Runway – Main Runway Works”- Contract Number NRTW-1008-CN.

• This method statement outlines the procedures to be followed in the protection of the existing gas pipelines using precast concrete slabs at locations shown on contract drawings and as directed by Client / Consultant.

3.0      Definitions

3.1     CM               Construction Manager

3.2     PE/SE           Project Engineer/Site Engineer

          3.3     CS                Chief Surveyor

          3.4     ME               Material Engineer

          3.5     ESHO           Environmental, Safety, and Heath Officer        

• References

4.1     Specifications:         Volume 3 – Section 9 – Part A

          4.2     Drawings:               Volume 2 – Section 8 – Part B – Civil, Mechanical and

                                                  Navaids, Drawing No. PGAD 745/1008/C/187, Rev. A                                

          4.3     B.O.Q                     Bill No. 18

          4.4     Method Statements: 1008-OAJ-MS-1002-R2 Method Statement for General

                                                  Excavation and Filling

                                                  1008-OAJ-MS-1012 Method Statement for Excavation

                                                  to Locate Existing Services

• Materials

• Class 50/20/R Concrete for Slabs
  • Class 40/20/S Concrete for Blindings
  • Reinforcement
  • Select Fill
  • Grade Stakes
  • Warning Tapes
  • Water Proofing Membrane
  • Traffic Cones
  • Formwork/Shuttering
  • Temporary Signs
  • Safety Barriers

• Tools, Plant and Equipment

• Dewatering Equipment (if required)
  • Light Vehicles
  • Surveying Instruments
  • Ladders
  • PPE (Personal Protection Equipment)
  • Manual Excavation Equipment
  • Cable Indicator (if required)
  • Ropes, Pipes and Supporting Materials
  • Dozer and Grader
  • Wheel Loaders
  • Trenchers
  • Vibrating Rollers
  • Dumper Trucks
  • Excavators
  • Water Tankers
  • Plate Compactors
  • Light Towers
  • Electrical Grinder/Saw
  • Loader
  • Crane
  • Generator
  • Concrete Plant
  • Air Compressors

7.0      Tools, Plant and Equipment

• Prior to the commencement of any activities, the workforce will receive an induction talk on the project site safety requirements. This induction talk will include both activity safety issues, as well as general safety requirements.

• Where possible hazards may arise from filling activities, the necessary safety measures will be taken to prevent accident or injury at all times. This may include barriers, warning tape/ net, signage, flagman, and proper lighting.

• Where work upon existing services may be required, the necessary work permits and safety equipments should be obtained prior to the activity commencement.  The necessary work permits from M/s GASCO and safety equipment should be obtained prior to the activity commencement.

• ESHO will enforce that Personal Protective Equipment be worn by site personnel at all times during construction activities.

• Heat Stress Training will be provided.

• Provisions of adequate cool drinking water, shade, and salt water tablets will be in place.
  • Plant & Equipment will be provided back-up alarms, lights, and all other applicable safety devices.

8.0      Prior Activities

• Prior to the commencement of any part of the work, the surveyor will locate and mark all live services that are present in the site (this will include services both above ground as well as buried).  These services will be clearly marked using stakes and warning tapes.  Near these services, only manual excavation will be permitted.  Excavation and procedures to locate existing buried services will be in accordance with 1008-OAJ-MS-1012 Method Statement for Excavation to Locate Existing Services. The CM/SE shall ascertain the actual locations of the existing gas lines. If the works conflict with any another existing services or road the CM/SE should obtain the Engineer’s approval for the protection or relocation (diversion) of these services, before commencing the work.

• Before commencement of any work within 30 meters from existing GASCO pipelines, a work permit should be obtained from the required authority.

• Detailed shop drawings will be submitted for approval regarding protection of existing gas pipelines using precast concrete slabs.

• After the shop drawings approval, inspection requests for site activities will be submitted to the Engineer.

• Procedure

• The concrete protection slabs will be precast off-site and will have to be properly coordinated with other activities (sewerage, storm water, road works, etc.) in the area and should basically follow the approved programme of works.

• Excavation, to the bund level, shall be in accordance with 1008-OAJ-MS-1002 Method Statement for General Excavation and Filing.
  • Levelling of the ground at the bund level will be done with the use of hand shovels. Plate compactors will be used to achieve the required level of compaction and homogeneous surface.  The rest of the activities will proceed after the approval of the inspector(s).

• A 1000 gauge polythene sheet will be laid on the approved finished bund surface.

• The shuttering/formwork for blinding concrete will be fixed in place as per the approved shop drawings. Shuttering/formwork shall be handled and erected as per specifications.  The shuttering/formwork will be checked, for conformance with the contract documents and shop drawings, by the surveyor and inspector(s).

• Concrete Class 40/20/S, for blinding, will be poured in accordance with the contract specifications and approved shop drawings.

• The cast-in-place blinding concrete will be cured in accordance with the contract specifications.

• The shuttering/formwork for the blinding concrete will be removed and the precast concrete slabs will be installed with the use of a crane.  All of these activities will comply with the approved shop drawings and will be coordinated with GASCO.

• The inspector(s) and surveyor will check the work (level, alignment, etc) continuously.

• After the above works are approved, backfilling operations will commence.  Select fill material will be used for backfill and the placing of the select fill shall be in accordance with the approved 1008-OAJ-MS-1002 Method Statement for General Excavation and Filling.
  • The select fill operations will be done with extreme care, especially during laying and compaction of materials above the protection slabs, and will need to be coordinated with the laying of electrical and communication ducts.

• After the laying of the select fill and completion of the duct laying activities, the service road will be constructed.

• After completion of works, the area shall be cleaned of any loose material. 

10.0  Responsibilities

1. The CM will coordinate with SE and ensure that the necessary resources to implement the approved method statement have been allocated to the task.

1. The SE will ensure that the site preparation activities are conducted according to the approved method statement.

1. The ME will ensure that the materials being used are in accordance to the project specifications and the approved method statement.

The ESHO, along with his team, will ensure implementation of all ES&H procedures related to the nature of the works being carried out and is in accordance with ES&H Plan.