Method Statement for Laying of 25mm Dia. AGL Duct in Existing Construction

CONTENTS

1. Purpose

• Scope of Work

• Definitions

• References

• Materials

• Tools, Plant  & Equipment

• Safety

• Prior Activities

• Procedure

1. Responsibilities

1. Attachments

1. Purpose

1.1       To ensure that the laying of the 25mm diameter AGL duct is 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.

• 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 laying of the 25mm diameter AGL duct in existing construction.

• Definitions

• CM                  Construction Manager
  • SE                   Site Engineer
  • CS                   Chief Surveyor
  • ME                   Material Engineer
  • ESHO              Environmental, Safety, and Health Officer
  • ITP                  Inspection and Testing Plan
  • AHA                 Activity Hazard Analysis
  • JHA                 Job Hazard Analysis

• References

• Specifications:             Volume 3 – Section 9 – Part A – General, Civil and Mechanical Infrastructure

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

Drawing PGAD 745/1008/C/704, Rev. A

• BOQ:                           Bill No. 5

• Materials       

• 25mm UPVC Duct
  • ISOLA N-S Grout Material (Non-Shrink, Non-Metallic)
  • Nitoseal 290
  • Water (complying to Clause 200.12A of contract specifications)
  • Hessian Cloth
  • Polythene Sheet
  • Warning Tapes
  • Safety Barrier
  • Traffic Cones

• Tools, Plant & Equipments:

• Surveying Instruments
  • Light Towers (if required)
  • Electrical Saw
  • Generator
  • Air Compressor
  • Power Wire Brush
  • Mechanical Mixer (Mortar Mixer with Moving Blades)
  • Trowel
  • Hopper
  • Mixing Bucket
  • Slow Speed Drill with Mixing Paddle
  • Water Measuring Jar
  • Personal Protective Equipment

• Safety

• 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.

• Front line supervisor will ensure that Personal Protective Equipment is worn by site personnel at all times during construction activities.

• Heat Stress Training will be provided.

• Adequate cool drinking water, shade, and salt water tablets will be in place.

• Plant and Equipment will be provided with back-up alarms, lights, and all other applicable safety devices.

• For AOA work, safety requirements as defined per Section 107 will be implemented. Specific safety training will be provided to personnel for AOA work.

• Prior Activities

• Prior to the commencement of the works, it will be ensured that all necessary equipment and tools are available.  Sufficient material, plant and labour will be made available to ensure a continuous process of application.

• A 100mm deep x 75mm wide chase will be sawn in the existing asphalt surface, using an electric saw.

• All loose dust and dirt from the chase will be removed using an air compressor.  The surfaces will be roughened by chipping or other mechanical means to assure bond of the grout to existing asphalt.

• It will be ensured that the surfaces to be grouted shall be clean, dry and free from dust, grease, oil, dirt laitance and other contaminants.

• The substrate will be saturated with water for at least two hours before placing grout, but ensuring that there is no free standing water just before placing grout.

• Consideration will be given to carry the grouting and backfill operations during the early morning or late in the afternoon when ambient temperature is decreasing.

• The unmixed ISOLA N-S Grout and Nitoseal 290 materials will be stored as per the respective manufacturer’s recommendation for high temperature working and storage.  As a general rule, the unmixed materials should be stored in a controlled temperature.  In the field, the materials have to be stored under temporary shade.

• Procedure

• Grouting Around AGL Duct

• Install the 25mm UPVC duct in the 100mm deep x 75mm chase, ensuring a cover of 25mm from the bottom of the chase.

• Calculate the total volume of ISOLA N-S grout that will be required to fill the hole.  Put the required amount of water into the mixer, and then slowly add grout while mixing. The range of mixing water can be varied between 3.40 to 4.50 litres per 25 kg bag of grout.  As a general rule, always start with the minimum water and add additional water to obtain the desired consistency.  The mixing water should be accurately gauged.  Mix for 3 to 5 minutes until mixture is smooth and homogeneous.  Ideally, the grout should be poured in one continuous operation.  If this is not practical, ensure that the mixing and pouring sequence in between batches is within 15-20 minutes.

• Immediately pour the grout into the chase.  Final grout level should be at a maximum of 20mm below the top of the chase.

• Finish the grout flush with a trowel.

• Cover the exposed section with a wet Hessian cloth and polythene sheet, and maintain this wet protection for 3 days.

• After the above works are completed and approved by the Engineer, application of Nitoseal 290 can proceed.

• Backfilling with Nitoseal 290

• After the ISOLA N-S grout has completely cured, clean the 20mm (maximum) groove by flushing it with water.

• Blow oil-free and dry compressed air to clean the groove free of all laitance, slurry, foreign matter, etc.

• Clean the groove with the power wire brush or abrasive blasting.

• Repeat the blowing procedure once again.

• Calculate the total amount of Nitoseal 290 required to fill the groove completely. Pour the entire contents of the liquid resin component of Nitoseal 290 into the mixing bucket.  Add the entire contents of the powder component whilst mixing with a slow speed drill attached with a mixing paddle.  Mix the components thoroughly for not less than 3 minutes ensuring a homogenous consistent mix.

• Pour the Nitoseal 290 directly into the prepared groove using a spouted container or watering can.
• Responsibilities

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

1. The SE will ensure that the site preparation activities are conducted according to the approved method statement, JHA and AHA.  The SE will also ensure that all in-situ tests, as required by the ITP, are implemented.

1. The ME will ensure that the materials being used are in accordance with the project specifications and the approved material submittals.

1. It is the site supervisor’s responsibility to organize the work in a safe manner to ensure that safety and protective equipment are being properly utilized.  He must also ensure that the AHA and JHA are implemented and the approved method statement procedure is followed and the ITP is applied.