Method Statement -Removal of USM and Ground Treatment Works

1.0 OBJECTIVE

     This Work Method Statement is to outline the sequence of activities, method and resources needed for the operation of unsuitable material’s removal and ground treatment works.

 

 2.0 SCOPE

 This method statement shall apply for excavation of unsuitable material and backfill with suitable fill works for (your project name). Details of the procedures contained herein may be modified based upon actual ground condition and site requirements.

 

 3.0 REFERENCES

Ø  Construction Drawings

Ø  Project Specifications

 

4.0 DEFINITIONS

       -Nil-

 

5.0 RESPONSIBILITIES

Ø  Safety Officer/Supervisor

Ø  Site Manager

Ø  Project Engineer

Ø  Surveyor

Ø  Site Supervisor

 

6.0 MATERIALS

Material to be used is as follows :-

Ø   As approved.

 

7.0 HANDLING AND STORAGE OF MATERIALS

Handling - Transport of materials shall be carried out by lorry or other suitable machinery.

Storage – stockpile at suitable area.

 

8.0 PLANT, MACHINERY AND EQUIPMENT

Ø  Lorry

Ø  Excavator

Ø  Dozer

Ø  Compactor

Ø  Backpusher

 

9.0 PREPARATORY WORK

         i.            Obtain relevant approved construction drawing from client / client’s representative.

        ii.            Carry out survey to obtain original ground level and submit to client / client’s representative.

      iii.            Carry out Mackintosh Probe Test to determine the depth of unsuitable material and submit the results to the client / client’s representative for decision on depth of unsuitable material that needs to be replaced.

      iv.            Plot the cross section for embankment and excavation of unsuitable material (USM) to determine the extent of width to be removed. The cross section  shall be endorsed by the Licenced Surveyor.

        v.            Set out the location and limits of work.

      vi.            Joint survey to record the excavated levels and proceed with excavation of USM and dispose to the designated dumping area.                         

 

10.0 WORK METHODOLOGY

         i.            Prepare access to the working area and plan for the lorry and plant movements. 

        ii.            Excavate the unsuitable material to the required depth as specified by the client / client’s representative and dispose at approved disposal area.

      iii.            Soil replacement (compacted suitable material in dry condition) or by free draining material to 0.3m above standing ground water level.

      iv.            Carry out field density test.

        v.            Repeat step (iv) until the required level is achieved. Carry out necessary tests as per Inspection and Test Plan.

      vi.            Submit Request for Work Inspection Form for joint inspection and joint measurement with client / client’s representative using Earthworks Inspection Checklists.

     vii.            On completion of joint inspection, request client / client’s representative to sign on the Request for Work Inspection Form and file as per Project Filing Index.

   viii.            Carry out computation and submit for claim.

 

11.0 TRAFFIC MANAGEMENT AND MONITORING

11.1 Maintenance of existing roads, footpaths and service drains, etc.

Ø  The construction team shall maintain all existing site excess, roads, footpath, service drain, etc. and reinstate any damage caused by any reason whatsoever during the progress of the works.

Ø  It will be the Safety Officer/Supervisor’s responsibility to ensure that ingress and egress to the site are kept free from obstruction brought about by the work on this site and in no way shall cause hindrance to traffic or ancillary works either by his own vehicles or by his work people, material, etc.

 

12.0   SAFETY PROGRAMME

Ø  The Safety Officer/Supervisor shall be responsible for submission of plans and drawings to the relevant Authorities for the construction of all the necessary temporary drains and desilting pits, safety nettings for the works. 

Ø  The Safety Officer/Supervisor shall provide adequate signboards at all strategic positions warning the public to keep away from the work site and erect temporary fencing and barriers where necessary around the site to prevent unauthorized trespassing during works.

Ø  To obtain permit to work (PTW) for the excavation 2.5m and above.

  

13.0   ENVIRONMENTAL PROGRAMME

All works should be carried out in accordance with best practice environmental management as defined in the EMP.

13.1    Site Access.

Ø  The access as well as the portion of public road and walkway connected with it shall be always kept clean and safe.

 

13.2   Temporary Work.

Ø  Existing drain shall be identified by contractor together with the flow of drain until discharge point in order to make use of it during clearing work. Silt trap shall be provided before any discharge of surface water within site towards existing drain. This work should be completed prior to the commencement of any activities.

Ø  Temporary earth drain shall be constructed along working area to retain the surface water from dismissal directly towards existing drain. Desilting work shall be carried out regularly and the existing drain will be maintained during work.

Ø  As the slope area will not be disturbed, the existing turf or grown grass shall be remain and only manually cut the grown trees without uprooting it. Plastic sheet /canvas will be provided on site on standby basis in order to be use as slope protection if necessary.

Ø  Any effluent discharges from the site must comply with the Third Schedule of the Environmental Quality (Sewage and Industrial Effluents) Regulation 1979.

 

13.3   Waste Management.

Ø  Any construction wastes, solid wastes and domestic wastes other than schedule wastes must be disposed-off at the approved disposal site. On site compositing for biodegradable waste is allowable but land filling and open burning activities for the solid waste are strictly prohibited.

Method Statement -Piling Works

1.0       INTRODUCTION

This Work Method Statement is to outline the installation of drive pile and testing for piling works.

 

2.0       SCOPE OF WORKS

This method statement shall apply for all piling works for (your project name). Details of the procedures contained herein may be modified based upon actual ground condition and site requirements.

 

Material, manpower, plant and equipment as below;

Material                                 : Spun pile 400mm dia. And 600mm dia.

Manpower                            : Piler, welder, operator and general workers.

Plant and equipment         : Hydraulic hammer, pile driver.

 

3.0       RECORDS

Contractor shall submit to the Superintending Officer the piling form format for approval prior to the commencement of piling works.

Contractor shall provide the Superintending Officer with two copies of the records for each pile.

These records shall have the following formation:-

 

a. Drawing Ref No.                                                             i. Length Form Toe to Ground Level  

b. Project Name                                                                  j. Initial Pile Length  

c. Block                                                                                 k. Extension Pile Length  

d. Pile No.                                                                             l. Total no. of extension  

e. Pile Size                                                                            m. Total Pile Length  

f. Type of Hammer & Weight of Hammer                      n. Final Set Per 10 Blows  

g. R. L. of Ground                                                                o. Length of Drop (M)  

h. R. L. of Cut-Off Level; of Driving                                  p. Remarks.  

 

Records of piles shall be made and submitted in the order in which the pile have been driven. Any unexpected driving conditions reported in accordance with, shall be note in the records.

 

4.0       HANDLING OF PILES

Contractor shall exercise the greatest care in the lifting and handling of piles and no pile shall be lifted other than by slinging through the lifting holes. All piles damaged during handling, driving or at any other time shall be replaced at contractor own expense.

 

5.0       PITCHING AND DRIVING

Piles shall be pitched accurately in the positions and driven to the appropriate lines and levels and to a predetermined set as directed by the Superintending Officer. Piles may be suitably constrained to maintain their correct position by means of guys or guides but the piles which has been deflected from its course, or has been incorrectly aligned shall be forcibly brought back to its correct alignment.

Sufficient care shall be exercised in handling and slinging of piles, and no pile shall be lifted other than by slinging from designed and approval lifting points.

Where piles are driven below the level of the bottom of the leads of the pile frame, extension leads shall be fitted.

Before the commencement of driving of each pile, the guides of the pile frame shall be checked for plumb in any two different directions and shall be maintained during driving to the entire satisfaction of the Superintering Officer (S.O.) or his representative. At no time during driving operation shall the center of the hammer or hydraulic ram be more than 50mm off center with respect to the center of pile being driven, in any direction.

Driving of a pile shall, as far as possible, be in continuous operation until the required set is obtained.

For rc square pile, during driving heads of the pile shall be protected by a helmet of cast steel or mild steel fitting closely around the pile. Packing of soiled hemp rope or plywood, 25mm thick, covering the head of the pile, shall be placed within the helmet to separate the helmet from the head of the pile. The top of the helmet shall be recessed and fitted with a timber stub dolly lift 300mm long. The packing a stub dolly shall be renewed as often as necessary to prevent damage to the piles.

For spun pile, when driving commence, the first few blows and meter of penetration shall be closely monitored to enable any initial deviation to be physically corrected. Large deviations in terms of position and inclination (in excess of specified tolerances) shall merit an extraction and re-drive at this stage if forcible corrections are not adequate. For deviations that inevitably occur at deeper penetrations, only measurements in the final set position shall dictate, amongst other factors, the pile acceptance or otherwise. Where driving depths go below the piling rig’s base level, a suitable temporary pile extension of known length and material properties shall be used to enable proper computation of the pile set.

Contractor shall maintain a record of the driving of all piles giving sets and other data required by the Superintending Officer and four copies shall be submitted to the Superintending Officer. All piles shall be driven to the shown on the Drawings or to such final set of depth as may be approved by the Superintending Officer.

The weight, type, height of fall for the hammer and the final set shall be strictly observed by the contractor but under main-con supervision.

The predetermined set must be obtained for three consecutive trails of 10 blows each before driving can be stopped.

 

6.0       BASIC FOR ACCEPTANCE OF INSTALLED PILES

a. The basis for the acceptance of installed piles is that the driving criteria and final set of a driven pile or the design criteria of any other type of installed pile which has been verified by successful load test shall form a basis, on which other piles are to be driven or installed and their performance compared.  

b. Contractor shall ensure that all the other piles are strictly driven or installed to the same conditions or better than the initial tested pile which passes the load test requirements, as any further pile chosen for load test which fails to meet the requirement shall be rejected and all costs for remedial piles and amendments to pile caps shall be borne by the contractor.

c. The pile sections and details have been designed to safely carry the maximum design load as far as the strength of the pile section itself is concerned and subjected to its proper handling. The safe bearing capacity of the pile will depend on the driving criteria adopted and the actual soil conditions and shall have to be verified by an initial load test. Any driving criteria or final set suggested to the contractor by the Superintending Officer shall be fully responsible in all aspects of the design and the contractor only responsible in the aspects of installation of the piles. Contractor shall have the right to adopt a different driving and final set provided their suitability are verified by a load test and also provided the stresses on the pile during driving shall not damage the pile.

 

7.0       HILEY FORMULA FOR PILE DRIVING CALCULATION

For driven piles, calculations are usually based on the Hiley formula, or on one of the many variations of this, designed to give more accurate results or great ease of calculation. The basic formula is:

(Refer to submission of blow count calculation using Hiley Formulae in separate submission).

This formula should only be used when piles are driven into sands, gravels or similar non-cohesive soils or into hard clay or into rock.

The capacity of driven piles is generally a matter of experience on the part of the piling contractor though empirical formula have been devised by many companies. The number of variables and the range of variability are usually too many and too great for even reasonable measurement, but the piling contractor’s estimate of the carrying capacity of one of these own piles is usually fairly accurate.

Temporary compression, C is assumed 14.0mm, fixed value for size of piles. The actual value shall be confirmed after actual set is determined and set calculation shall be recalculated based on actual temporary calculation.

In general, the coefficient of restitution is 0.25 to 0.4 and the hammer coefficient is 0.8 to 0.85.

 

8.0       VERTICALITY OF PILE

For the checking of the verticality of the leader (guide) throughout the driving process, we will use the plumb stand at the side of machine and spirit level. During pitching and installation, the verticality of the pile will be continuously monitored and plumbed to ensure the pile is centrally in line with the pile axis to receive the ram to prevent pile whip, twist or rotation.

 

9.0       PILE JOINTING AND SPLICING

9.1          Pile jointing and splicing

Piles shall be joined at the specified position using the recommended method or propriety systems as required.

Equipment – Welding Set. The type of welding rod are E6013 and size of welding rod shall used 3.2mm and 5.0mm. 

The required setting and hardening times for primers and epoxies, where used, shall be adhered to when pile joints are made, to ensure a safe and effective joint.

The pile will be extended by butt-welding the steel plates on the pile heads. On completion of welding, the slag will be chipped off and wire brushed to receive red-oxide paint.

When welding joints, no gaps shall be allowed and full bearing at the connecting plates between the driven and the extended length shall be ensured. Pile driving will then be resumed after the required setting/hardening times for the weld to develop its strength.

 

 

9.2          Weld Tests

Ø  During production of welded tube piles, at least one radiograph or ultrasonic test approximately 300mm long shall be required on each end of a length as a spot check on weld quality. This shall be taken on a circumferential or longitudinal weld and its position shall be as directed by the S.O.

                                 i.            For tubes of wall thickness 12mm or less, three spot radiographs, one at each end of each length of the tube as manufactured and one at position to be chosen at the time of testing by the S.O; and spot check radiographs as required by the S.O on the weld joints between strip lengths

                                ii.            For tubes of any wall thickness, continuous ultra-sonic examination over the weld, supplemented where necessary by radiographs to investigate defects revealed by the ultrasonic examination.

 

Ø  Weld tests shall be performed by radiographic or ultrasonic methods as specified. Provided that satisfactory result are being obtained, one test of a length of 300mm shall be made 10% or more of the number of welded splices in the case where the load will be carried by the wall or section of the pile will not normally exceed 10%. Results shall be made available to the S.O within 10 days of completion of the tests.

 

9.3          Pile Load Test

 

10.0     PILE CUT-OFF

Piles shall only be cut-off after securing the directive and acceptance by the S.O.  This is to ensure that any re-driving work that would be required can still be carried out when such situations warrant.

The value for pile cut-off level must be formally agreed and any piles that need to be ‘brought up’ to the required cut-off level must meet the S.O.’s agreement and guidelines.

Where pile cut-off levels are below ground, excavation sides shall either be sloped or protected by an earth retaining structure to prevent collapse of the excavated pit.

Where pile cut-off levels are below water level, suitable enclosing structures (e.g. cofferdams) shall be installed to exclude water from the works.

 

11.0     HEALTH, SAFETY & ENVIRONMENT PROGRAMME

11.1     Health & Safety

Ø  Safety induction to be conducted to all new workers that involved to this activity and safety toll box meeting shall be conducted every day to remind the workers about concerning the safety.

Ø  All workers shall be provided with PPE (Personal Protective Equipment) and shall be worn at all time on site. Safety Manager / Safety Supervisor shall ensure all the workers wear all the safety equipment provided

Ø  All workers shall be advised to report any accident or injury to supervisor.

Ø  Proper and adequate provision of temporary signage’s and barricades at diversions and temporary haul road as necessary (if applicable).

 

11.2     Environment

Ø  All workers shall educate on good environmental management practices and well- disciplined to environment.

Ø  The garbage bin shall be provided at the working area and Supervisor shall ensure its must be collected regularly and disposed-off at the approved dumpsite.

Ø  All workers shall ensure that all tools and equipment machinery are in good condition to avoid any oil leakage that could harm to environment.

Method Statement -Earthworks

1.0 OBJECTIVE

To outline the method statement by which the earthworks are carried out. This shall include method statement for excavation and backfilling works.

2.0 SCOPE

 The activities for earthwork shall consist of many stages that include:

·         Preliminary work

·         Excavation

·         Excavation in rock (if any)

·         Embankment fill

·         Slope protection

 

3.0 REFERENCES

·                Construction Drawings

·                Project Specifications

·                Surveying Field Book

 

4.0 DEFINITIONS

       -Nil

 

5.0 RESPONSIBILITIES

·                Safety Officer/Supervisor

·                Site Manager

·                Project Engineer

·                Land Surveyor

·                Site Supervisor

 

6.0 MATERIALS

       -Nil

 

7.0 HANDLING AND STORAGE OF MATERIALS

Handling         : Transport of materials shall be carried out by dump trucks / other suitable machinery.

     Storage            : Nil

 

8.0 PLANT, MACHINERY AND EQUIPMENT

Excavator                    : For bulk excavation and slope trimming.

Dump truck                : For transporting the material.

Bulldozer                     : For ripping, loosening of earth, pushing and spreading the earth in layers for compaction.

Motor grader              : For spreading, leveling and shaping works

Backhoe                      : For general excavation in trenching works.

Water bowser            : For spraying of water.

Compactor                 : For compacting soil

Back pusher               : For spreading and leveling.

Survey equipment    : Theodolite / leveling.

 

9.0 PREPARATORY WORKS

Earthworks is based on the information and data obtained in the following document:-

 

5                

6                

7                

8                

9                

9.1               Earthworks shall be carried out in accordance with standard code of practice (refer to BS 6031 : 2009) approved by consultant/consultant’s representative.

9.2               Approved Pre Com plan endorsed by relevant Authority and Topographical Survey endorsed by Licensed Surveyor.

9.3               Obtained relevant approved construction drawing from consultant/consultant’s representative.

9.4               Set out the location, centre lines and limits of works.

9.5               Set out the toe peg and finish level for the work.

9.6               Set temporary earth drain and outlet structure before earthwork start.

9.7               Prepare temporary shoring or any slope protection if required for work safety.

9.8               During earthwork, temporary earth drain, sediment pond and outlet structure shall be maintained regularly.

 

10.0 WORK METHODOLOGY

 

10.1  Preliminary Works

         i.            Temporary perimeter drain with silt trap and lorry wash trough shall be constructed as per drawings.

        ii.            Temporary drain shall also be constructed from identified ponding areas to drain out the water prior to any inspection and testing.

      iii.            Joint inspection shall be conducted with the Consultant Representative to identify location of unsuitable /over wet materials and marked on a layout plan.

      iv.            Suitable earth shall be imported from cutting area to be identified by the Consultant Representative.

        v.            Survey to establish existing ground level (EGL) and proposed formation level shall be in accordance with contract, specification and drawings.

      vi.            Surveyors shall establish center line, boundary, slopes and level markers using wooden pegs with appropriate tags or colour coded for easy reference. OGL survey drawing shall be submitted before any actual earthwork to commence. OGL drawing shall comply with the contract requirement.

     vii.            All encumbrances shall be cleared or isolated with proper boundary markers.

   viii.            Inspection shall be conducted to confirm PBM and proposed TBM.

 

10.2  Excavation

         i.            The excavation works shall proceed first at the location of cut areas detailed on the EGL survey drawing to perform the waste and treatment pond.

        ii.            Prior to any cutting / excavation works, the surface of the ground shall be cleared of any waste, rubbish material, organic material and etc using the excavator to scrap the top surface.

      iii.            Excavation shall commence using excavators to form the required slope and formation level which are control by the survey pegs. Excavation to be kept dry whether in open cut or in trench.

      iv.            The excavated common material (not inclusive of rock) loaded into the dump truck and transport to the designated filling area or temporary stockpile area approved by Consultant Representative.

        v.            Any unsuitable materials identified as such shall be removed and transferred to other designated area upon approval from the Consultant / PMC Representative.

      vi.            Excavation materials for embankment fill shall be tested and complied with the clause 2.4.1(e) of the Technical Specification.

 

10.3  Excavation in Rock (If any)

         i.            Normal hydraulic excavation method cannot be employed for excavation of rock in trench or pit.

        ii.            For this, the rock shall be loosened either by drilling or blasting or by pneumatic tools. Normally pneumatic breaker or explosives are used to disintegrate the rock formation depending on the type and quantity of the rocks. The excavated rock shall be transport to the Consultant Representative approved stockpile area.

      iii.            A method statement shall be formulated and submitted upon encountering new method of excavation in rock (if necessary).

 

10.4 Embankment Fill (if necessary)

         i.            Suitable fill materials shall be hauled by dumper trucks to the designated fill areas.

        ii.            If suitable fill materials cannot be spread immediately, it shall be deposited at temporary stockpile area and then shall be shaped and compacted to ensure proper surface drainage.

      iii.            The fill material shall be deposited, spread, levelled and compacted using vibro compactor exceeding 20tonne. The maximum loose thickness for fill is 500mm each layer. For compaction of embankment slope, the fill shall be extended 600mm beyond the design slope and then trim back to the required slope angle. Degree of compaction for the whole embankment below the top 300mm of the subgrade shall not less than 90% of the Maximum Dry Density (MDD).

      iv.            When compaction has reached the full berm height, motor grader shall be used to grade the surface to the line, grade and level for the next construction activities.

        v.            The fill layer shall be built up evenly over the full width or up to the roadworks limit only (to facilitate the subsoil drain construction) with sufficient width (to ensure adequate compaction) and shall be always maintained with sufficient camber to avoid water ponding.

      vi.            In-situ Field Density Testing and CBR test shall be carried out on the subgrade and subsequent layers at the rate specified in contract or as deemed necessary at location to be selected by the Consultant Representative.

 

Subject to FDT result approval, compaction of the layers shall be continued as the following :-

·         If FDT passed – proceed next layer

·         If FDT failed – proceed with rectification and retesting

 

     vii.            Upon confirmation of the Consultant Representative, the subsequent layer shall be carried out as per sequence until formation level is reached.

   viii.            Each inspection sheet shall be signed off every day by contractor and the Consultant Representative.

 

10.5  Slope Protection

         i.            A gentle gradient shall be adopted to have a more stable slope.

        ii.            Where the condition of high gradient (i.e. steep slope), turfing of the area shall be applied or staggering of slope shall be done (if applicable) to prevent any erosion due to weather or other means.

 

10.6   Inspection and Test Plan

As the progress of the preparation for the earthwork, there are few inspections involve for conformation and assurance of the specified requirements.

The inspections required are:

                       i.             Field Density Test

Ø  Core Cutter Method

Ø  Sand Replacement Method – small cone

Ø  Sand Replacement Method – large cone 

                     ii.             Soil Compaction Test with Soil Classification Test (Proctor)

                    iii.            California Bearing Test

Ø  Lab CBR Test (soaked)

Ø  In-situ CBR Test using Core Cutter method (soaked)

Ø  In-situ CBR Test using Load to carry out at site.

                    iv.             Grading Test (Sieve for Analysis)

                     v.             Mackintosh Probe Test

The testing equipment and laboratory apparatus required are as below:

·         A balance accurate to 0.01g

·         A balance accurate to 0.5g

·         Air-tight non corrodible metal container (50mm OD x 25mm high)

·         Desiccators

·         Scoops

·         British Standard sieves as follows :

75mm, 63mm, 50mm, 37.5mm, 28mm, 20mm, 14mm, 6.3mm, 5mm, 3.35mm, 2mm, 1.18mm, 425mm, 212mm, 150mm and 63mm and appropriate receivers.

·         Cone penetrator or Casagrande liquid apparatus

·         Other suitable accessories and equipment necessary to carry out density test (including In-situ Test) sieve analysis, liquid limit analysis, CBR, Mackintosh probe and etc.

 

11.0 TRAFFIC MANAGEMENT AND MONITORING

11.1 Maintenance of existing roads, footpaths and service drains, etc.

The construction team shall maintain all existing site excess, roads, footpath, service drain, etc. and reinstate any damage caused by any reason whatsoever during the progress of the works.

It will be the Safety Officer/Supervisor’s responsibility to ensure that ingress and egress to the site are kept free from obstruction brought about by the work on this site and in no way shall cause hindrance to traffic or ancillary works either by his own vehicles or by his work people, material, etc.

 

12.0 SAFETY PROGRAMME

12.1    Temporary Works and Public Safety

The Safety Officer/Supervisor shall be responsible for submission of plans and drawings to the relevant Authorities for the construction of all the necessary temporary drains and desilting pits, safety nettings for the works.

The Safety Officer/Supervisor shall provide adequate signboards at all strategic positions warning the public to keep away from the work site and erect temporary fencing and barriers where necessary around the site to prevent unauthorized trespassing during works.

 

13.0  ENVIRONMENTAL PROGRAMME

All works should be carried out in accordance to best practice environmental management as defined in the EMP.

13.1    Site Access.

The access as well as the portion of public road and walkway connected with it shall be kept clean and safe at all times.

 

13.2    Temporary Work.

Existing drain shall be identified by contractor together with the flow of drain until discharge point in order to make use of it during clearing work. Silt trap shall be provided before any discharge of surface water within site towards existing drain. This work should be completed prior to the commencement of any site clearing activities.

Temporary earth drain shall be constructed along clearing area to retain the surface water from dismissal directly towards existing drain. Desilting work shall be carried out regularly and the existing drain will be maintained during site clearing work.

As the slope area will not be disturbed, the existing turf or grown grass shall be remain and only manually cut the grown trees without uprooting it. Plastic sheet /canvas will be provided on site on standby basis in order to be use as slope protection if necessary.

Any effluent discharges from the site must comply with the Third Schedule of the Environmental Quality (Sewage and Industrial Effluents) Regulation 1979.

 

13.3       Waste Management.

Any construction wastes, solid wastes and domestic wastes other than schedule wastes must be disposed-off at the approved disposal site. On site compositing for biodegradable waste is allowable but land filling and open burning activities for the solid waste are strictly prohibited.