Method Statement for Construction of Open Grouted Riprap Formed

CONTENTS

1. Purpose

• Scope of Work

• Definitions

• References

• Materials

• Plant  & Equipment

• Safety

• Prior Activities

• Procedure

1. Responsibilities

1. Attachments

1. Purpose

1.1       To ensure that the open grouted riprap formed channel 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 construction of open Grouted Riprap Formed Channel (Type 1).

• 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

• BOQ:                           Bill No. 7

• Material         

• Concrete grades 40/20/S
  • 150mm sized rock
  • Cement
  • Sand
  • Water
  • Polythene sheet
  • Hessian cloth
  • Polyethylene joint filler
  • Joint sealant
  • Formwork / shuttering
  • Warning tapes
  • Traffic cones
  • Traffic lights
  • Safety barrier

• Tools, Plant & Equipments:

• Excavator
  • Wheel loader
  • Dumper truck
  • Water tanker
  • Plate compactor
  • Hand tamping tools
  • Spirit level
  • Measuring tape
  • Hammer
  • Hand planer
  • Concrete chisel
  • Carpenter chisel
  • Plastic trowel
  • Steel trowel
  • Broom
  • Personal Protective Equipment
  • Wire Nails
  • Air compressor
  • Generator
  • Electric saw
  • Concrete vibrator

• 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

• Final approval for grouted riprap formed channel details should be obtained from the Engineer, through the shop drawings submittal process.

• The Surveyor will locate and mark all live services that are present in the site (this includes above ground services as well as buried services).  These services (electric, telephone, gas, oil, chemical, water, etc.) will be clearly marked using stakes and warning tapes.  Near these services, special precautions will be undertaken and coordination with the Engineer will be carried out to avoid any damages during the excavation and compaction process.  Any existing service, if exposed during previous excavation will be clearly marked, protected, and properly supported during all activities.

• Procedure

9.1       Excavation

• Trapezoidal trench for the Grouted Riprap channel shall be excavated to the lines and grades indicated on the approved shop drawings by using an excavator and in accordance with sub-clause 201.2 “Excavation” of the contract specifications.
  • The excavated material shall be removed by dumper trucks and heaped or disposed off according to sub-clause 201.2.1 of the contract specifications.
  • The excavated sides and bottom shall be watered, levelled and compacted.
  • Compaction shall be conducted by using plate and cylinder compactor at the channel’s bottom and hand tamping tools at the sides, to the satisfaction and approval of the Engineer.

            9.2       Casting of 75mm thick Concrete Blinding Grade 40/20/S

• Approval of the excavation and compaction of the open channel by the Engineer shall be followed by erection of the side formwork and laying of  1000 Gauge polythene sheets.
  • Construction joints shall be provided every 5 meters and expansion joints every 25 meters as shown in the shop drawings.
  • Concrete grade 40/20/S (75mm thick) shall be poured and levelled in three stages (base and two sides).
  • The concrete shall be protected by polythene sheet after finishing and wet Hessian cloth covered with polythene sheet after final set.
  • Concrete surface shall be kept continuously and thoroughly wet for a curing period of seven days.

9.3       Placing of 150mm thick Grouted Riprap

• Once the curing of blinding is completed, 150mm sized approved rock shall be placed in such a manner as to produce a reasonable well graded mass of rock with the minimum practicable percentage of voids, and shall be constructed to the lines and grades indicated on the shop drawings.
  • Placing of material shall begin at the base and progress up the slopes.
  • The finished riprap shall be free from pockets of small stones and clusters of larger stones.
  • Riprap shall be grouted with Cement / Sand mortar in a ratio of 1:4, with enough added water.
  • Expansion joints every 25m and Construction joints every 5m shall be provided.

1. Responsibilities

1. The CM will coordinate with SE and ensure that 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.