1. TITLE Method Statement for the Backfiling Works. 2. SCOPE OF WORKS 2.1 General Description ·          The scope and pur...

Method Statement for Backfilling Works

11:20 PM 0 Comments

1. TITLE

Method Statement for the Backfiling Works.

2. SCOPE OF WORKS

2.1 General Description

·         The scope and purpose of this method statement is to outline the general requirements and precautionary measures which should be taken into consideration during backfilling works. Either between foundation base, behind walls or other related to the Permanent Work or Structures and to ensure that works are according to the drawings, standards and project specification.

2.2 Plant and Equipment

§  Water

§  Approved Back fill material

§  Warning tape, Barriers and Lighting as necessary

§  Shovels

§  Trucks

§  Water Tanks

§  Roller/Plate Compactor

§  Surveying Equipments

§  Personal Protective Equipments

§  Others to be provided as needed

2.3 Materials

§  Suitable Backfill Material

2.4    Site Planning and Preparation

2.4.1     Site Management Plan and Access Route

·         Upon receiving approved construction drawings, all concreting routes / locations will be set out and marked routes plan and access shall be divided by geographical zones. The information will be provided to the construction team for implementation.

2.4.2           Permits

·         Backfill work permits should be secured ahead of time from HSE Department.

2.4.3           Communication

·         Communication on site will be by GSM mobile phones.

2.5      Work Methodology

2.5.1           Pre-activity Meetings

Coordination between different disciplines will be done prior to commencing the concreting of particular structure based on the submitted work for inspection, Tool box meeting should be conducted based on the approved Method statement & Risk assessment by the execution team. A pre-activity meeting will be held in order to provide the following information:

·      The location of the structure to be backfilled particular grid, type, area, volume etc.

·      All necessary inspection to be performed for backfill works,

·      Related Interfaces, coincidences and integration with all partners involved.

·      Related NCR, Technical query, Technical deviation or concession request.

·      Ensure shop drawings are in place and approved Released for Construction Drawings.

The pre-placement activity meeting Safety task analysis risk reduction talk, has to be set to assign all tools required, rate of pouring, vibration and finishing procedures, staff requirements, testing specialties, traffic flow, number of pumps, emergency plans if any, etc.

2.5.2           Scheduling

The backfilling works shall be scheduled well in advance to allow the control of geometry, block-outs, embeds, waterproofing and other activities in the backfill area.

2.5.3           Work Sequence

2.5.3.1      Backfill Works Preparation

·      The surveyor would conduct the site survey to mark/stake-out the lines and levels of the objective excavation as per indicated in the approved shop drawings.

·      The area must be clear from debris, organic matter, oils and other unsuitable materials prior to backfilling works

·      All other activities such as repairing of concrete, waterproofing, etc. shall be complete and approved by the Engineer prior to commencement of works.

·      Necessary equipment and tools (roller, plate-compactor, survey equipment, etc.) will be arranged as per work requirements.

·      A designated lot of suitable backfill material shall be assigned and to be marked by flags.

2.5.3.2      Backfilling Works Execution

A.      Back filling for Buildings and Structures:

·         The backfill will be laid in every layer and to be compacted in every 150 mm thickness.

·         A steel rod should be driven into the ground to indicate the level of the layers.

·         The material is to be placed in layers within the effective range of compaction that the maximum loose (uncompact) thickness of each layer does not exceed 200 mm.

·         Each layer will be compacted to a min. 95% MDD of the material by roller vibrators in wider spaces and by hand tamper in narrow spaces.

·         The backfill materials, which shall be approved by client/consultant and shall be tested by independent certified local laboratory in Qatar. Stocked file near site to be arrange for easily access.

·         Backfilling will be executed in layers and the thickness of the layer is subjected to the backfilling depth. (Refer to ITP for detailed test and inspection).

·         All adjustment of moisture content shall be carried out in such a way that the specified moisture content remains uniform throughout compaction.

·         No completed fill layer shall be covered by the next layer until it has been tested, inspected and approved by the Engineer.

B.      Backfilling of MEP services, trenches etc.

·      Any MEP services that required backfilling shall be performed in every layer.

·      Backfilling of trenches shall be started only after the inspection of the laid services and the execution clearance shall be issued.

·      Where the designated minimum cover cannot be achieved, they shall be bedded and surrounded with 150 mm of grade 20 concrete.

·      Any sleeves crossing the trench will be encased with concrete if needed.

C.      Testing & Initial Acceptance Criteria

Testing shall be performed on in situ soil by a third party laboratory. (Refer for ITP for frequency and applicable standards for the tests to be performed).