Method Statements For Excavation And Backfilling Works

Method Statements for Test Pile of Access Trestle andCoal Unloading Jetty_The purpose of this Method Statement is to describe the methodology for structural work of Method Statements For Excavation And Backfilling Works and to details out the steps to be taken in meeting the technical requirements of Van Phong 1 thermal power plant project

General comments: (1) Project specifications and code/ standard applied for earth works indicated to be listed Noted that code/standard for APPROVED underground works, filled & bedding Approved AP AC APPROVED WITH COMMENT materials and so on Contractor to revise the correction and resubmit (2) Over-excavation for rock or soil ground to be more specific requirement and NA NOT APPROVED For Approval Revise the correction and resubmit before proceeding RE REVIEWED acceptance Information acknowledged with no comment (3) For deep hole, pit, foundation, please RC REVIEWED WITH COMMENT consider the access to go up and down for Information acknowledged with comments safety issue Note: Approval or comment does not relieve the Contractor of all obligations covered under contract (4) Protection slope during construction to Discipline: Civil and Structural 08 Jan 2020 Date: be considered particularly in rain season A 19-Dec-2019 For Approval JH Choi KS Kim ET Kim REV DATE DESCRIPTION Approved Checked Prepared OWNER VAN PHONG POWER COMPANY LIMITED PROJECT Van Phong BOT Thermal Power Plant Project Status □Approved □Approved with Comment □Not Approved □Reviewed OWNER’S ENGINEER Pöyry Switzerland Ltd EPC CONTRACTORS IHI–TESSC–CTCI–DHI CONSORTIUM PROJECT DOCUMENT No VP1-0-L4-C-GEN-10008 REV A DOCUMENT TITLE METHOD STATEMENT FOR EXCAVATION AND BACKFILLING WORKS EPC EPC DOCUMENT No REV VP1-0-L4-C-GEN-10008 Doosan Heavy Industries and Construction A VAN PHONG BOT THERMAL POWER PLANT PROJECT CONTENTS PREFACE 2 MACHINERY & EQUIPMENT RESPONSIBILITIES PROCEDURE AND SEQUENCE QUALITY CONTROL ENVIRONMENT, HEALTH AND SAFETY (EHS) of 14 - Definite what the 'General excavation and backfilling' is VAN PHONG BOT THERMAL POWER PLANT - Applicable case of this MS (For example: PROJECT onshore open excavation and max meter depth or ect.) - Format in one font 1.0 PREFACE The purpose of this Method Statement is to describe the methodology involved in general excavation and backfilling works and to details out the steps to be taken in meeting the technical standards and EHS requirements • Plant Project: VP1 BOT Thermal Power Plant • Company/Owner: Van Phong Power company limited(VPCL) • Contractor: DHI 2.0 MACHINERY & EQUIPMENT No Description Excavator Loader Dump Trucks Roller or small vibrating roller Water Tanker Total Station Automatic Level with Tripod and Staff Rod Hand Tools Barriers 10 Submersible Pumps 11 Generator 12 Rammer 3.0 RESPONSIBILITIES Q’ty Who is DMPP and what attachment? • It is overall responsibility of Project Manager to organize resources prior to perform construction activities as per project specification in compliance with the quality, schedule & safety requirements • EHS Manager will ensure in coordination with Site Engineer that all measure/construction taken shall be maintained till completion of job • It is the responsibility of Construction Manager/Site Engineer that construction activities are executed according to the relevant project specification in compliance with the quality, schedule & safety requirements • DMPP will ensure that all works are performed safely according to the attachment • The relevant DMPP Supervisor will ensure that the work is carried out in accordance with this method statement and project specification • The QC Inspector will ensure that the work is executed according to the requirements of quality dossier are fulfilled of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT 4.0 PROCEDURE AND SEQUENCE Describe clearly basic requirement of site clearance before each excavation, backfilling 4.1 Site Clearance • It has been done before the commencement of any excavation or placing of fill material 4.2 Mobilization • Prior to entering the working area, all equipment and machinery will be inspected by safety personnel Safety personnel shall be responsible for preparing and providing relevant documents • All machineries, equipment and material shall be entering using the designated entrance gate 4.3 Equipment Setting-up • All material, machineries and equipment shall be located at designated area • Setting-up of equipment will be done by Supervisor by adhering to all safety measurement and requirement outline • Upon completion of set-up, joint inspection will be carried out to satisfy all parties and ensure all relevant equipment/machineries shall be complied with safety rules and regulation 4.4 Survey • Prior to the work commencement, construction drawing will be reviewed to check of its latest issuance for construction and all essential details are given It will be checked that the intermediate dimension agreed with the overall dimension • The setting-out will be made at the beginning stage of the work by referring to the construction drawing and all reference points will be made necessary for the entire work This will be acquired and develop method of checking and cross-checking on all setting-out operations When principal lines and levels haste be set-out, it would be advised to be the relevant persons 4.5 Layout and Marking • Layout and marking will be marked using surveying equipment having a valid calibration certificate and will be Excavation should be divided by depth so that in each case, can design: 4.6 Excavation Necessary space for manpower working or not Kind of slope and slope protection or shoring 4.6.1 Excavation by Mechanical Means system Kindof of existing barricade, distance to edge line • If required trial holes will be dug with hand tools to confirm the locations services before Loading distance to edge line carrying out excavation using the excavators to widths, lengths and5 depths in theequipment Type as of given excavation De-watering system specification/drawings ect verified by QC • For foundation excavation, leave the bottom layer of minimum 50mm undisturbed while mechanical excavation and subsequently remove this layer manually when the blinding concrete is about to be placed This prevents softening or deterioration of the excavated surface If hard strata appear then jack hammer and breaker can be used 4.6.3 Excavation Concrete foundations, Manholes and Miscellaneous Structures • Excavation for concrete foundation, concrete valve boxes, manholes and appurtenant structures shall include the work of removing all earth, sand, gravel, quicksand, stone, loose rock, solid rock, clay, shale, cement, of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT hardpan, boulders and all other materials necessary to be moved in excavating the trench for the pipe and other structures; maintaining the excavation by shoring, bracing and sheeting or well pointing to prevent the sides of the trench from caving in whilst in progress and removing sheeting from the trench after pipe has been laid • Trench support system shall be suitable for the soil structure, depth of cut, water content of soil, weather conditions, superimposed loads, vibration The method shall be ensuring safety of workers on the trench • Sloping sides of trench to the angle of repose at which the soil will remain safely at rest • Shoring trench sides by placing sheeting, timber shores, trench jacks, bracing, piles, or other materials to resist pressures surrounding the excavation • Trenches shall be of the necessary width for proper laying of pipe Care shall be taken not to over-excavate The bottom of the trenches shall be accurately graded to provide uniform bearing and support for each section of the pipe along the entire length of the barrel of the pipe • Grading of trenches shall be performed to avoid interference of water and sewer lines with other underground utilities and structures • Excavation for manholes, concrete foundations, and similar structures shall be sufficient to leave at least 400mm in the clear between the outer surfaces and the embankment or timber that may be used to hold and protect the banks • Excess materials shall be hauled away from the construction site or otherwise disposed of on designated disposal area • TYPICAL FOUNDATION Rock excavation shall be included in this MS or separated submission of MS for rock excavation - showing barricades - drainage trench if any EXCAVATION PLAN DUMP TRUCK EXCAVATOR SECTION A-A of 14 Excavation should be divided by depth so that in each case, can design: Necessary space for manpower working or not VAN PHONG BOT THERMAL POWER PLANT Kind of slope and slope protection or shoring PROJECT system Kind of barricade, distance to edge line Loading distance to edge line Type of excavation equipment De-watering system ect 4.6.4 Excavation on Underground Service Pipeline • If required trial holes will be dug with hand tools to confirm the locations of existing services before carrying out excavation using the excavators to widths, lengths and depths as given in the specification/drawings • Pipe trenches shall not be opened too far in advance of pipe laying • Width of the trench shall be minimum of 1M (excavator bucket width) but in any case shall not be less than the outer diameter of the pipe plus 300 mm on either side to allow proper compaction of the side fill material • Bottom of the trench shall be trimmed to form the pipe bed as per the pipe gradient Where solid rock is encountered at invert level, it shall be removed by breaking with jack hammer Please input slope protection ratio & angle? 1:n Pipe 300 - showing barricades - drainage trench if any Is there enough for - if deep foundation, people walking & working access path for inspector space? is required 300 Min 1,000 4.6.5 Maintenance of Excavated Area • Continuously monitor the dimension/level of excavation to avoid over cutting If any accidental over cutting takes place, fill and compact with suitable material to the desired level • Remove any undesirable material (vegetation, organic soils, etc.) encountered during the excavation Take necessary measures to keep the excavation free from water by dewatering wherever required • Arrange shoring so that it does not interfere with the progress of work As work proceeds, remove the shoring carefully without causing any damage to the excavation • What is meaning of properly slope, please describe ratio & angle of slope If any accidental slips or settlement occurs in the excavated area, properly filled by selected materials 4.6.6 Cutting and Sloping the Sides of Excavation • Whenever there are chances of sliding, properly slope side of excavation Trim the slopes by hand or be It is a very common mechanical means to uniform batters Trim any rock or boulders appearing in the face of the slope and description, not know what deep what slope, space for remove it altogether if it seems unstable working, drainage • If any rock is removed, fill the resulting void with compacted material • Any overhanging, loosed or unstable material shall be removed • In cutting where the strata consist of earth overlaying rock which is required to be cut to a slope of 1:2, the face of the rock shall be given its appropriate slope up to the junction of the rock and earth and the latter shall be stripped to form a bench and sloped to the gradient as specified of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT • In all cuttings, whether in earth or rock, undulations in the general plane of the slope will not be permitted • The excavation shall be so arranged that the working areas are adequately drained throughout the period of construction 4.6.7 Removal of Rocks • Supplement compaction • requirement on the surface of excavation pit • Should rock be met in the course of excavation, it shall be removed by approved means The written consent of the OWNER shall be obtained on occasion DHI wishes to use a method The OWNER shall be fully informed by DHI as to the steps and precautionary measures taken to safeguard the surroundings It shall be determined the danger zone likely to be created and ensure that no damage is caused to persons or property on site 4.7 Backfilling 4.7.1 Placing of Fill Material • Filling material shall comply with Code/ Standard Please make it clear Where the concrete protective coating is applicable the area shall be cleaned thoroughly and protective coating shall be applied in accordance with the approved coating specification before backfilling work • Approved suitable excavated material from the site can be used for backfilling/general filling If the excavated material is of a poor quality, obtain fill material from approved borrow pits or any other source • This is backfill work after completion of permanence structure, 500mm Filling area surface shall be kept free from water, such as materials and debris layer thickness is not accepted • Fill materials shall be placed and spread in uniform horizontal layers across the full area of the foundation able to provide material as per specifications without segregation The thickness of each layer after compaction shall not exceed 300 mm from third layer, first and second layer shall not exceed 500mm • Fill in areas not intended to receive concrete foundations shall be placed and spread in uniform layers not exceeding 300 mm after compaction from third layer, first and second layer shall not exceed 500mm • Filling operations shall be programmed so as to ensure that the specified compaction is attained throughout • Fill materials shall be laid, spread and leveled using manpower and compacted by using roller compactor to the required levels • No person shall be permitted to position or operate machinery in a manner likely to endanger that person or others in vicinity of the excavation area • Filling? Field density test (FDT) shall be carried out randomly on agreed area before proceed to the next excavation site or layer • Setting out the level again for rechecking the excavation level as stated in the drawings • Each lift shall be evenly spread and moistened or dried by other means so that the required density will be produced • Rocks or stones larger than 100 mm, shall not be used for fill Place compacted fill in successive horizontal layers of loose material not more than 300 mm thicktowhen compaction by rollers or vibrators,uniformly and 150 mm is Backfilling adjacent structures shallisbemade placed and compacted inwhen such mechanical manner astamping to prevent required eccentric loading Field upondensity or adjacent to the structures Slopes bounding within areas backfilled test shall be carried out once for each layer ofor compaction areato or be once for each shall layer of 400 sq.m be stepped or serrated to prevent sliding of the fill 4.8 Compaction and Leveling the Fill • During compaction, maintain the moisture content of fill material usually +/- percent of overall moisture of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT content If required, add clean water to the fill material in order to maintain the necessary moisture content • Around new (or existing remaining) concrete foundations or other sub structures, not compact by rolling instead, use mechanical rammers or plate compactors to compact the space in vicinity of concrete structure • After compaction, level the surface free from undulations using suitable equipment • Mechanical compaction shall be accomplished by the use of foot rollers, pneumatic tire rollers, vibrating rollers or other mechanical tampers of a size and type necessary to achieve the required degree of compaction • The type, size and efficiency of compaction equipment shall be subject to the OWNER approval and shall be capable of achieving the specified degree of compaction Minimum fill compaction will be as follows: • The mechanical rammers or plate compactors shall be used to compact the confined space in vicinity of Not accepted concrete structure instead of rollers • After compaction, the surface shall be leveled using suitable equipment • By using adequate capacity of vibrio-max roller about to passes are ensured to achieve minimum required compaction on 300mm thick layer from third layer, first and second layer shall not exceed 500mm 4.9 Dewatering • The DHI shall all pumping, shall build all drains and all the work necessary to keep the trench and pipes free from water during the progress of the work of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT What is meaning of DP? • What is process of disposal? Please describe detail how to control water before discharge? It shall be on proper steps to ensure that all water disposal is done in line with good engineering practices and is compliance with national & local laws, rules and codes • DP will take the proper steps to ensure that the backfilling works are kept free from water until completion of works This can be achieved by continually dewatering water from the area to the designated drainage system • Excavation and removal of the mud will be done by backhoe and dump trucked working simultaneously Please describe how far • The submerged pumps will be arranged sufficiently so that the excavation and removal of the mud can be barricade will be installed from the edge of excavation preceded with no obstruction 4.10 Protection • Provide barricades or warning tape with post and restrict access as appropriate to prevent damage to work in place • DHI shall be responsible for protection of work in place against displacement, damage, or loss until OWNER’s acceptance Any work and subsequently damaged, lost or displaced shall be repaired and replaced to the OWNER’s satisfaction 4.11 Cleaning • Thoroughly clean, rake, wash, flush or sweep as required to clean adjacent improvements of materials covered as part of this work to submitting for OWNER’s acceptance • Contractor shall provide all labor, equipment, materials and other items as required to perform clean up as required by the OWNER • Finish grading of areas affected by this work shall be required as part of clean up • The roadway including shoulders, slopes, ditches, and borrow pits shall be smoothly trimmed, and shaped - Code and standard should be stated at the beginning of the document - Frequency of testing should be stated in structure ITP so maintained until accepted Any surplus material not suitable for spreadingeach along the road to (5000m3 widen theapplied for site leveling only) existing shoulder or raise the grade shall be disposed of as specified above - State the requirement of field density of both excavation and backfill by machinery or other satisfactory methods to the lines, grades and cross-sections as established and shall be 4.12 Testing: • Tests for un-compacted materials shall be in accordance with ASTM/TCVN or equivalent method and tests for compacted materials shall be in accordance with ASTM D/TCVN or equivalent method Each test shall be executed every 5,000 m3 according to the instruction of the OWNER QUALITY Control Code and standard should be stated at the beginning of the document 4.6 The Site Inspection and Test Plan (ITP) for this work summarize various characteristics to be checked The concerned Site Engineer/Foreman will be responsible to ensure stage wise compliance for this operation and the Site QA/QC Engineer/Inspector will carry-out quality control checks and report the inspection results 4.7 Codes and Standards All excavation and fill works shall be in accordance with the Contract Part III-2 Exhibit B1 Tech Spec Section ASTM D1557 and 4254 shall be applied as an applicable code for the density test Relevant TCVN codes shall be applied for material laboratory tests ASTM D1194 shall be applied for Plate Load Test ASTM D6938 shall be applied in case Nuclear Density Gauge is used for site density test AASHTO T27 Standard shall be applied for sieve analysis of material of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT ENVIRONMENT, HEALTH AND SAFETY (EHS) 6.1 Responsibilities • The Safety Manager is responsible for the overall safety of the construction site His responsibilities include site inductions ensuring work permits are valid, accident reports, number of man-hours worked and ensuring all works are carried out in the safest possible manner consistent with good construction practices In case of imminent danger the site supervisor has to stop the work immediately The Safety officer at site is equally responsible from stopping the work in the above case 6.2 Safety • Personal Protective Equipment (PPE) will be issued to all workers such as safety shoes, hard hat, working gloves, safety goggles, reflective vest and safety harness for workers who will be assigned in elevated places 1.8m and above • Wearing of the basic PPE will be enforced fully • All new recruits will undergo proper orientation and safety induction before they could deploy at site for work • Place necessary warning signs as required • Provide flickering lights and reflectors while working in the night time • Where material must be stacked, make sure that they are staked on a firm and level base and in tidy manner • No waste, debris, toxic chemical, oil grease and etc from excavation and backfilling activities shall be spilled or burned on/in the ground, or discharge into any watercourse These wastes stored in drums/ containers and taken away and disposed of in the approved manner • Ensure that proper access is provided before entering excavation area • Always obey speed limits and traffic signs for ingress and egress from the site • Barricades/Signs will be provided sufficiently and maintained, as precautionary measures during the entire stage of construction, to protect the work and safety of the workmen • Prior to using any machines/equipment at site, ensure that they will be inspected and certified by qualified person • Operators and drivers are to be equipped with valid driver's/operator's license or permit from concerned government agency • Periodic Preventive Maintenance will be made on all equipment and machines • Lifting equipment as well as its accessories such as sling wire, nylon sling, shackles, chain blocks crane hook and latch will be inspected prior to using • Any potentially dusty material being transported from work sites will be securely contained Transporting vehicles, etc., will be monitored to prevent overloading and over-filling • Weight of dump truck containing the excavated material will not be exceeded the limited weight allowed by the nation, local and traffic law • Ensure all workers and equipment’s working overtime are properly accounted and obtained permit/ approval from DHI EHS Manager prior to carry-on works of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT • Periodic refresher trainings, tool box talk and audit shall be conducted • Excavation and delivery of materials are prohibited during heavy rains • All personnel should know the locations of fire extinguishers, communications, manual alarms • All personnel should be aware of assembly points, escape routes, emergency contact numbers Please explain, the deep excavation can be considered confined space entry or not? What kind of PTW will be applied? 10 of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT 6.3 Job Safety Analysis JOB SAFETY ANALYSIS VP1 BOT Thermal Power Plant Project (Developing a habit of analyzing methods to identify hazards & unsafe practices than developing solutions that control, minimize or eliminating hazards List of All Job Steps List of All Known Hazards How to Eliminate Hazards A Survey Works A.1 Instrument falling down and hit a workmen A.1 Area where the instrument is to be must be well compacted A.2 Instrument dropping ground by accident A.2 Focus and concentrate all the time during work execution B.Working Operation During Night Time to A.3 Stuck into the muddy area A.3 Always beware and walk on designated access A.4 Pegs splatters into the eyes A.4 Always wear safety PPE B.1 Working operation of the equipment may cause injury to personnel due to poor visibility of the area B.1a Must provide sufficient lightings on the entire working area B.1b All equipment must be fitted with appropriate safety device and ensure all lights are operational not obscured by dirt and mud B.1c Supervisor and safety personnel shall always be present for the necessary working B.1d All workers must be wearing visible PPE B.2 Generator (Diesel) equipment oil leakage during operation B.2a Daily check of the equipment prior to start of work B.2b Regular check &monitoring of the equipment prior to use B.2c Provide sundry containment protection under the equipment to prevent contamination of soil by oil spillage B.3 Oil/chemical storage B.3 Diesel/chemical shall be scored in sundry containment & MSDS requirement shall be communicated with all concerned B.2b Regular check &monitoring of the equipment prior to use B.2c Provide sundry containment protection under the equipment to prevent contamination of soil by oil spillage This is not in compliance with Doosan's HSE risk management procedure Please clarify the risk assessment as job safety analysis, when the both documents shall be prepared Please the intensive study on Doosan's procedure for proper document It seem that there is no review from Doosan's safety team on this document 11 of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT JOB SAFETY ANALYSIS VP1 BOT Thermal Power Plant Project (Developing a habit of analyzing methods to identify hazards & unsafe practices than developing solutions that control, minimize or eliminating hazards List of All Job Steps List of All Known Hazards How to Eliminate Hazards Excavation of Soil, Rock and Trenching C.1 Slip and trip of workers C.1 Secure confirmation by EHS manager regarding assigned engineers and workers C.2Fall of workers and equipment C.2 Excavation plan and excavation work checklist must be available at the work site C.3Cave-in of excavation walls C.3a Assign licensed and experienced operator C.3b Excavation site must be cordoned with safety warning tapes and/or hard barricades painted with red & white whichever is applicable including provision of sufficient lightings and blinker lights during nighttime C.3c Install adequate safety signs such as excavation in-progress, keep-out deep excavation, etc C.3e Assign experienced and trained personnel /workers C.3f Provide spoil area away at least meters from the edge of the excavation to avoid cave-in or collapse in case excavated materials will not be hauled or disposed at once C.3g Provide sufficient shoring system, sloping of ground or other equivalent means such as sheeting, cross bracings, trench shield or box and jacks, benching, etc whichever is applicable C.3h Prohibit movement of vehicles and equipment near the edge of the excavation that may result to side wall excavation cave in or collapse due to severe ground movement 12 of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT JOB SAFETY ANALYSIS VP1 BOT Thermal Power Plant Project (Developing a habit of analyzing methods to identify hazards & unsafe practices than developing solutions that control, minimize or eliminating hazards List of All Job Steps List of All Known Hazards How to Eliminate Hazards D Backfilling Works D.1 Slip and trip of workers D1 Implement method statement / procedures on safe backfilling works D.2 Fall of workers and tools /equipment D.2a Strict supervision during backfilling works D.2b Wearing of the required PPE D.2c Assign licensed and experienced operator D.2d Assign experienced and trained personnel /workers E Trenches E Falling from height and cavein E.1 Earth excavated to be stored meters away from excavation area E.2 Vehicle to be kept in meters from edge of excavation E.3 Experienced and trained workers E.4 Essential PPE in use F Environmental Conditions During Excavation Works F Extreme environmental condition such as high temperature & humidity and strong wind F.1 Implement safety procedures &guidelines on heat stress F.2 Inspect excavation and adjacent areas for possible hazardous atmosphere and any other condition that may present a hazard F.3 Suspend / stop all operations during extreme temperature & humidity and high wind G Dewatering G.1 Pump equipment (Diesel Engine) oil leakage during operation G.1a Daily check of the equipment prior to start of work G.1b Regular monitoring of the equipment sin order to control and prevent oil leakage and other engine trouble G.1c Provide sundry containment protection under the equipment to prevent contamination of soil by oil spillage 13 of 14 VAN PHONG BOT THERMAL POWER PLANT PROJECT JOB SAFETY ANALYSIS VP1 BOT Thermal Power Plant Project (Developing a habit of analyzing methods to identify hazards & unsafe practices than developing solutions that control, minimize or eliminating hazards List of All Job Steps List of All Known Hazards G.2 Electric shock due to without ground external box on pump station and circuit breakers How to Eliminate Hazards G.2a Provide adequate ground and circuit breakers G.2b Designate electrician/operator for the pump equipment H Disposal of Excavated/Exces s Materials H Collision between equipment H.1 Prepare access for the equipment to be provided I Dust Control I.Vehicle/equipment transporting of excavated soil to the disposal I.1 Spraying of water on the road as required to ensure no dust flying 14 of 14