Method of structure excavation a1 ENG s1

GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN CONTENTS General .3 General Locations .3 Construction Schedule .9 Site Organization Chart Materials 10 Equipment and Tools 11 Major Types of Structure Excavation 11 a 7.1 Structure Excavation without Temporary Cofferdam .12 b 7.2 Structure Excavation with Temporary Cofferdam 17 Quality Control 23 Safety Control 23 10 Environmental Control 24 Appendixes Appendix I - Typical Construction Sequence (Structure Excavation without Temporary Cofferdam) Pages Attached Appendix II - Typical Construction Sequence (Structure Excavation with Temporary Cofferdam) Pages Attached Appendix III - Inspection and Test Plan Pages Attached Appendix IV Page Attached - Inspection sheet forms Total 36 pages General Revision A1, 23th Jul, 2010 page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Structure Excavation shall be undertaken in accordance with Section 03200 of the General Specifications This method generally applied to the Structure Excavation for Foundation of Bridge, Culvert, Sub-drain, Box Culvert, and other structures as directed by the Engineer This work defines and describes the cutting and excavation of the original ground at locations where pile cap or footings, box culvert and other structures are to be in placed in accordance with the designed bottom elevation Excavation for Structures such as Box Culvert and Abutment located at Embankment areas and on Soft Ground conditions shall be in accordance with the Engineer’s instruction for residual settlement due to consolidation Where the Engineer orders the excavation after embankment has been placed, this extra excavation in the embankment will be measured for payment as Structure Excavation Backfilling and restoration works of adjacent area on completed structures, disposal of unsuitable excavated material, dewatering works and related works to free the accumulation of ground water and artificial run off water inside excavated area shall be part of Structure Excavation except the removal or diversion of existing water flows Excavation shall be done in accordance with the lines and grades as indicated on the approved working drawing Accurate quantity will be calculated based on approved working drawing General Locations Location and intended type of excavation is shown as below table Detail shall be indicated on the working drawing No A7/01 A7/02 A7/03 A7/04 A7/05 A7/06 A7/07 A7/08 A7/09 Bridge Name Station Chau Que Thuong bridge Khe Sang Bridge Khe Hong Bridge Tan An Bridge Khe Can Bridge Xom Danh Bridge Thin Thung I Bridge Thin Thung II Bridge Tan Thuong Km190+487 35 Km191+353 15 Km193+379 65 Km194+765 Km195+233 50 Km198+438 50 Km199+050 50 Km199+131 40 Km199+860 Revision A1, 23th Jul, 2010 Excavation without cofferdam Excavatio Excavati n with a on with part of cofferda cofferda m m P1,P2 A1,A2 A1,P1,P4,P5,P6,P7, P8 P2,P3 A1,P3,,P4,A2 A1,P2,P3,P4,P5,A2 P1,P2 P1 A1,P1, A2 A1,P1,P2, A2 A1, P1,A2 A1, P1,A2 A1,P1,P3,A2 P2 page Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 A7/10 A7/11 A7/12 A7/13 A7/14 A7/15 A7/01C A7/02C A7/03C A7/04C A7/05C A7/06C A7/07C A7/08C A7/09C A7/10C A7/11C A7/12C A7/13C A7/14C A7/15C A7/16C A7/17C A7/18C A7/19C Bridge Khe u Bridge Khe Dai Bridge Ngoi bong Bridge Tan Tien Bridge Cam Con Bridge Xom Cam Bridge Pipe culvert Underpass Box culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Underpass Box culvert Pipe culvert Drainage Box culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Underpass Box culvert Pipe culvert Pipe culvert Revision A1, 23th Jul, 2010 Km204+591 05 Km201+815 50 Km 207+936.55 Km 209+329.70 Km 209+690.65 Km214+679 00 Km191+780 00 Km191+960 00 Km191+980 00 Km192+162 00 Km192+300 00 Km192+394 00 Km192+550 00 Km192+720 00 Km192+890 00 Km192+895 00 Km192+930 00 Km193+155 00 Km193+650 00 Km193+810 00 Km194+015 00 Km194+280 00 Km194+486 00 Km194+540 00 Km195+137 A1,A2 A1, A2 P1 　 A2 A1 P2,P3,P4.P5 　 A1,A2,P1 P1.P2 　 A1.A2 P1 A1,A2 　 Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 A7/20C A7/21C A7/22C A7/23C A7/24C A7/25C A7/26C A7/27C A7/28C A7/29C A7/30C A7/31C A7/32C A7/33C A7/34C A7/35C A7/36C A7/37C A7/38C A7/39C A7/40C A7/41C A7/42C A7/43C A7/44C Drainage Box culvert Underpass Box culvert Pipe culvert Pipe culvert Pipe culvert Underpass Box culvert Pipe culvert Underpass Box culvert Drainage Box culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Underpass Box culvert Drainage Box culvert Underpass Box culvert Underpass Box culvert Underpass Box culvert Underpass Box culvert Underpass Box culvert Underpass Box culvert Underpass Box Revision A1, 23th Jul, 2010 00 Km195+674 00 Km195+912 00 Km195+957 00 Km196+118 00 Km196+374 00 Km196+460 00 Km196+475 00 Km196+832 00 Km197+032 00 Km197+760 00 Km198+060 00 Km199+200 00 Km199+390 00 Km199+540 00 Km200+028 00 Km200+300 00 Km200+700 00 Km200+862 00 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Km201+685 Without cofferdam Km202+354 Without cofferdam Km203+420 Without cofferdam Km204+319 Without cofferdam Km204+610 Without cofferdam Km205+415 Without cofferdam Km206+239 Without cofferdam page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 A7/45C A7/46C A7/47C A7/48C A7/49C A7/50C A7/51C A7/52C A7/53C A7/54C A7/55C A7/56C A7/57C A7/58C A7/59C A7/60C A7/61C A7/62C A7/63C A7/64C A7/65C A7/66C A7/67C A7/68C A7/69C A7/70C A7/71C A7/72C A7/73C A7/74C A7/75C A7/76C culvert Underpass Box culvert Drainage Box culvert Drainage Box culvert Drainage Box culvert Drainage Box culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Pipe culvert Underpass Box culvert 2.70x4.00 Underpass Box culvert 2.70x4.00 Underpass Box culvert 2.70x4.00 Underpass Box culvert 2.70x4.00 Underpass Box culvert 2.70x4.00 Underpass Box culvert 4.50x6.00 Underpass Box culvert 2.70x4.00 Underpass Box Revision A1, 23th Jul, 2010 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Km206+865 Without cofferdam Km202+380 Without cofferdam Km203+408 Without cofferdam Km204+770 Without cofferdam Km206+360 Without cofferdam Km201+280 Km201+645 Km202+070 Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Km202+190 Km202+770 Km202+990 Km203+230 Km203+860 Km204+113 Km204+307 Km204+940 Km205+270 Km205+488 Km205+830 Km206+095 Km206+220 Km206+708 Km206+775 Km207+000 Km207+452 Km207+609 Km207+834 Km208+040 Km208+400 Km208+835 Km210+141 Km211+035 Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 culvert 2.70x4.00 Underpass Box culvert 4.50x6.00 A7/77C Underpass Box culvert 2.70x4.00 A7/78C Underpass Box culvert 2.70x4.00 A7/79C Underpass Box culvert 2.70x4.00 A7/80C Underpass Box culvert 2.70x4.00 A7/81C Underpass Box culvert 2.70x4.00 A7/82C Underpass Box culvert 2.70x4.00 A7/83C Underpass Box culvert 2.70x4.00 A7/84C Underpass Box culvert 4.50x6.00 A7/85C Underpass Box culvert 2.70x4.00 A7/86C Underpass Box culvert 3.20x5.00 A7/87C Underpass Box culvert 4.50x6.00 A7/88C Drainage Box culvert (3.0x3.0) A7/89C Drainage Box culvert 2(3.0x3.0) A7/90C Drainage Box A7/91C culvert 2(3.0x3.0) Drainage Box culvert 2(3.0x3.0) A7/92C Pipe Culvert A7/93C D1500 Pipe Culvert D1500 A7/94C Pipe Culvert A7/95C D1250 Pipe Culvert D1250 A7/96C Pipe Culvert A7/97C D1250 Pipe Culvert D1250 A7/98C Pipe Culvert A7/99C D1250 Pipe Culvert A7/100C D1250 Revision A1, 23th Jul, 2010 Km211+565 Km211+983 Km212+473 Km213+015 Km213+625 Km214+230 Km214+440 Km214+856 Km216+244 Km216+697 Km217+277 Km217+980 Km210+120 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Km211+051 Without cofferdam Km211+543 Without cofferdam Km217+355 Km207+000 Km207+112 Km207+290 Km207+444 Km207+580 Km207+810 Km208+060 Km208+230 Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 A7/101 C A7/102C A7/103 C A7/104C A7/105 C A7/106C A7/107 C A7/108C A7/109 C A7/110C A7/111 C A7/112C A7/113 C A7/114C A7/115 C A7/116C A7/117 C A7/118C A7/119 C A7/120C A7/121 C A7/122C A7/123 C A7/124C A7/125 C A7/126C Pipe Culvert D1500 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D2000 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert Revision A1, 23th Jul, 2010 Km208+440 Km208+608 Km208+897 Km210+153 Km210+393 Km210+515 Km210+640 Km210+810 Km211+063 Km211+310 Km211+450 Km211+640 Km211+800 Km212+146 Km212+520 Km212+720 Km212+948 Km213+068 Km213+180 Km213+410 Km213+540 Km213+635 Km213+815 Km213+880 Km214+050 Km214+155 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 A7/127 C A7/128C A7/129 C A7/130C A7/131 C A7/132C A7/133 C A7/134C A7/135 C A7/136C A7/137 C A7/138C A7/139 C A7/140C A7/141 C A7/142C A7/01R A7/02R A7/03R D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1250 Pipe Culvert D1500 Pipe Culvert D1500 Pipe Culvert D1500 Rataining Wall(left) Rataining Wall(left) Rataining Wall(left) Km214+361 Km214+773 Km214+836 Km215+038 Km215+140 Km215+300 Km215+464 Km215+580 Km215+732 Km216+060 Km216+500 Km216+600 Km216+710 Km216+910 Km217+180 Km217+906 km209+637km209+663 km209+995km210+033 km210+024km210+086 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Construction Schedule Construction Schedule shall be referred to latest approved Overall Schedule and to be updated monthly and weekly For each location, schedule for structure excavation shall be submitted together with working drawing Site Organization Chart Revision A1, 23th Jul, 2010 page GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Organization chart for management and construction of structure excavation work is as follows: Materials The proposal of materials will be submitted to the Engineer for approval and material tests in laboratory shall be carried out prior to commencement of work under the Inspection by the Engineer The general description and list of materials is as follows The detailed information for material shall be submitted separately as proposal for materials Revision A1, 23th Jul, 2010 page 10 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN 5-1 Material List List of required material is shown below Equipment and Tools Table1 - List of Minimum Equipment and Tools Note: Above stated schedule of equipment shall be increased in quantity if required and necessary Major Types of Structure Excavation Generally, Structure Excavation without Temporary Cofferdam will be applied However, Structure Excavation with Temporary Cofferdam shall be applied depending on the following cases: Structure is located on or adjacent to existing pond, canal and channels Structure is located on or adjacent to existing roads or highways and important facilities Actual conditions after verify and ascertain the reasons and factors for application of Temporary Cofferdam and after approval by the Engineer Revision A1, 23th Jul, 2010 page 11 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Structure Excavation without Cofferdam "Procedure of construction" "Action to be taken" Preparation Work Confirmation of Working Drawing for Cofferdam Site Clearance and Demolition Check Ground Condition Working area preparation Establish Limit of Work Cutting and Excavation Works/ Hauling out of Excavated Material Temporary Drainage Construction Trimming/Leveling Works Granular Backfill Confirmation of Topographic Survey of Orig ground Set survey marking points Check existing soil formation (unsuitable material) Check slope of excavation Check the location of pump pit and temp drain Inspection and Approval of Bottom Elev of Excav Confirmation of Subsoil Foundation by the Engineer Formworks setting/ Placing of Blinding Stone Inspection of limit and Elev Bott of Blinding Stone Confirmation of Approved Material Casting of Lean Concrete Inspection of limit and Elev Bott of Lean Concrete Confirmation of Approved Material Pile head Treatment Acceptance Commitee for Cast-In-Place Concrete Piling Pile Cap Construction Pier Construction Backfilling /Restoration Works Check Elevation of Cut-Off level and Pile Head condition Confirmation of As Built for Cast-In-Place Concrete Piles Method Statement shall be submitted separately Method Statement shall be submitted separately Confirmation of As built for Structure by the Engineer Confirmation of Approved Material Confirmation of Compaction by the Engineer 7.1.2 Construction Method 7.1.2.1 Preparation Work Revision A1, 23th Jul, 2010 page 13 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Confirmation of Working Drawing including Site Layout plan The type of Structure Excavation shall be shown on Working Drawing Prior to starting excavation operations in any area the Contractor shall:  Take steps on his own initiative to regulate the natural drainage of the water flows on the surface of the ground to prevent flooding of excavation  Ensure that all necessary site clearance and demolition in that area has been performed in accordance with these Specifications  Notify the Engineer sufficiently in advance of the beginning of any excavation so that cross sectional elevations and measurements can be taken of the undisturbed ground The existing ground adjacent to the structure shall not be disturbed without the permission of the Engineer 7.1.2.2 Establish Limit of Work Establish excavation limit including the working area inside excavation and shall be in accordance with the approved working drawing Topographic survey of original ground which had been approved shall be applied to calculate the quantity for structure excavation Average elevation of original ground shall be calculated based on topographic survey The elevation of the bottom of site clearing shall be 20cm below the average elevation of the original ground Depth of 20cm below the average elevation of original ground shall be under Site Clearing works Excavation below bottom of site clearing shall be applied to structure excavation Such elevation shall be shown on working drawing Marking elevation shall be provided prior to excavation at site 7.1.2.3 Cutting, Excavation and Trimming Works 7.1.2.3.1 First step of excavation shall be undertaken using excavating equipment Bottom of excavation shall be up to 20cm average above the designed bottom of structure excavation Depths shall be checked and monitored carefully to prevent damage and disturb the subsoil of foundation 7.1.2.3.2 Pumping pit may be provided located at one or two corners inside the excavation area Temporary drain canal sloping towards the pumping pit may be provided around the perimeter of the excavation pit and may be constructed outside the perimeter of the lean concrete Location of pumping pit may be shown on submitted working drawing 7.1.2.3.3 Excavated materials found to be suitable for backfill and embankment shall be hauled to a designated area and shall be protected to keep dry Unsuitable materials upon approval by the Engineer shall be disposed separately The vertical sides of the excavation shall be sloped approximately to a minimum of 1:0.5 for good stability The slope may be properly covered with plastic sheet against soil collapse and erosion during rainfall During excavation, care shall be taken in Revision A1, 23th Jul, 2010 page 14 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN consideration not to damage the Cast-in-Place piles at locations where pile cap or footing are to be in-placed 7.1.2.3.4 Second step is manual trimming, leveling and excavation shall be done on the remaining 20cm average from the first step of excavation up to the designed bottom elevation of structure excavation The base shall be compacted using a portable compacting machine or equivalent In cases that unsuitable or soft material still exists at the designed bottom elevation of excavation, removal and replacement of such will be checked and confirmed by the Engineer If found to be unsuitable material it shall be removed and replaced 7.1.2.3.5 After completion of excavation, all loose and displaced material shall be removed, leaving a neatly and solid finished bed for construction of footing or pile cap or base of box culvert and other structures 7.1.2.3.6 Substructure and Base foundation limit shall be marked with survey stakes for setting up boundaries of the blinding stone, lean concrete and pile cap 7.1.2.3.7 Completed Excavation shall be Inspected and Approved by the Engineer prior to construction of any permanent bedding or structure Same procedure shall be done for base of box culvert and other structures 7.1.3 Blinding Stone 7.1.3.1 Establish limit of boundaries of blinding stone for setting side forms 7.1.3.2 Approved material for Blinding Stone shall be placed following the submitted working drawing The in-placed blinding stone shall be compacted thoroughly to the satisfaction of the Engineer using portable compacting equipment or equivalent At the area around the cast-in-place pile, a mechanical rammer or equivalent equipment shall be used in the compaction taking care not to damage concrete piles Tolerance on thickness and elevation shall be ±20mm 7.1.3.3 Completed blinding stone shall be inspected and approved by the Engineer prior to construction of lean concrete layer 7.1.4 Lean Concrete 7.1.4.1 Revision A1, 23th Jul, 2010 Lean concrete shall be placed to the elevation and thickness as indicated on working drawing and shall be cast within the defined boundaries by setting side forms Placing shall be carried out either by direct pouring, excavator or by crane and concrete bucket page 15 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN 7.1.4.2 After consolidation and screeding to the correct plane and elevation, the concrete shall be floated to a smooth finish, the surface being free from depressions or projections The newly placed concrete shall be neatly finished and leveled to the design elevation as indicated on the drawing Tolerance on thickness and elevation shall be ±13mm 7.1.4.3 Curing of lean concrete shall be carried out after completion of finishing Curing shall be done by spraying water or by covering the exposed surface with vinyl sheet 7.1.4.4 Compressive strength test specimen may be taken from the lean concrete delivered to site Frequency shall be in accordance with Inspection and Test Plan Item 2.b 7.1.5 Pile Head Treatment Refer to approved method statement for cast-in-place concrete pile - GRBCC-MSCIPCP-A2-EN 7.1.6 Construction of Substructure Method Statement shall be submitted separately 7.1.7 Backfilling and Restoration 7.1.7.1 Backfill shall be placed in layers of 15cm thickness when using mechanical rammer equipment for compaction However, when vibration roller equipment is available for compaction, backfill shall be placed in layers of 20cm Backfill shall be compacted to the satisfaction of the Engineer Whenever necessary, backfill materials shall be sprinkled with water to maintain the required moisture 7.1.7.2 In cases that the area of Structure Excavation is under permanent roadway, such as Pipe Culvert and Box Culvert, backfill shall be carried out in accordance with Clause 3.11- “Protection of Structure”, Section 03400 – “Embankment construction” of the General Specifications and in accordance with Approved Method Statement for Road Earthwork GRBCC-MS-RE-A1-EN 7.1.7.3 Granular Backfill shall be placed behind Abutment and around pipe culvert and box culvert as shown on the approved shop drawing Granular Backfill shall be placed in 15cm each layer up to the designed elevation Compaction shall be done using proposed compaction equipment up to 95% of the maximum dry density as determined by AASHTO T180 Detail shall be shown on Working Drawing Revision A1, 23th Jul, 2010 page 16 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 7.1.7.4 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Backfilling shall be placed equally on both sides to the designed elevation or structures located in permanent embankment such as box culverts and pipe culverts Backfilling shall not commence until the concrete has not achieved sufficient strength 7.1.8 Cleaning Up Site Upon completion of backfilling works, all excess materials and rubbish shall be removed and disposed to designated area, leaving the site neat The site shall be of almost the same condition as the surrounding b 7.2 Structure Excavation with Temporary Cofferdam This defines the cutting and removal of existing ground and hauling out of excavated material inside the temporary cofferdam Structure Excavation with Temporary Cofferdam will be applied depending on the following cases: Structure is located on or adjacent to existing pond, canal and channels Structure is located on or adjacent to existing roads or highways and important facilities Actual conditions after verify and ascertain the reasons and factors for application of Temporary Cofferdam and after approval by the Engineer Design and proposal for application of cofferdam has been approved by the Engineer on locations where structure excavation without temporary cofferdam is not feasible In such cases, Temporary Cofferdam shall be applied to protect the excavated area for construction of structure and to prevent hazardous effect on surrounding area Each case shall be shown on Working Drawing Criteria and construction sequence including design calculation for Cofferdam work shall be submitted separately Working area inside the cofferdam shall be sufficient for construction of substructure The method of construction of Temporary Cofferdam for structures located on existing roads or highways and near existing important facilities shall be in consideration on the requirement of Related Authority Typical Construction Sequence for Structure Excavation with Temporary Cofferdam is attached on Appendix II 7.2.1 Typical Construction Flow Revision A1, 23th Jul, 2010 page 17 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Structure Excavation with Cofferdam "Procedure of construction" Preparation Work "Action to be taken" Confirmation of Working Drawing for Cofferdam Site Clearance and Demolition Check Ground Condition Working area preparation Grading and Leveling Works Establish Limit of Work Confirmation of Topographic Survey of Orig ground Set survey marking points Driving of Steel sheet pile for Cofferdam Check elevation of bottom and top of cofferdam Excavation/ Hauling out of Excavation Temporary Drainage Construction Trimming/Leveling Works Granular Backfill Confirm work sequence of Cofferdam Check elevation of excavation Check the location of pump pit and temp drain Inspection and Approval of Bottom Elev of Excav Confirmation of Subsoil Foundation by the Engineer Formworks setting/ Placing of Blinding Stone Inspection of Limit and Elev Bott of Blinding Stone Confirmation of Approved Material Casting of Lean Concrete Inspection of Limit and Elev of Lean Concrete Confirmation of Approved Material Pile head Treatment Acceptance Commitee for Cast-In-Place Concrete Piling Pile Cap Construction Pier Construction Initial Backfilling Works Check Elevation of Cut -Off Level and Pile Head condition Confirmation of As Built for Cast-In-Place Concrete Piles Method Statement shall be submitted separately Method Statement shall be submitted separately Confirmation of Approved Material Check Elevation Confirm as built of structure Confirmation of compaction by the Engineer Removal and Dismantling of Cofferdam Final Backfilling / Restoration Works Confirmation of Sequence of Construction of Cofferdam Confirmation of Approved Material Confirmation of compaction by the Engineer 7.2.2 Construction Method 7.2.2.1 Preparatory Works Revision A1, 23th Jul, 2010 page 18 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Confirmation of Working Drawing and Design Calculation of Temporary Cofferdam Preparation of working area for construction of Temporary Cofferdam Prior to starting Excavation operations in any area, the Contractor shall:  Take steps on his own initiative to regulate the natural drainage of the water flows on the surface of the ground to prevent flooding of excavation  Ensure that all necessary site clearance and demolition in that area has been performed in accordance with these specifications  Notify the Engineer sufficiently in advance of the beginning of any excavation that cross sectional elevations and measurements can be taken of the undisturbed ground The existing ground adjacent to the structure shall not be disturbed without the permission by the Engineer 7.2.2.2 Construction of Temporary Cofferdam 7.2.2.2.1 Established limit of Temporary Cofferdam for driving steel sheet piles with minimum 1m clearance from each side of the pile cap allowing enough area for formwork and mobility of the workers; as well as the arrangement of drain and canal and pumping pit However, in cases where the cofferdam is to be constructed on or adjacent to road, highways and important facilities, near existing structures, where area is limited, less than 1m clearance of steel sheet piles from the side of pile cap shall be proposed Topographic survey of original ground which had been approved shall be applied to calculate the quantity for structure excavation Average elevation of original ground shall be calculated based on topographic survey The elevation of the bottom of site clearing shall be 20cm below the average elevation of the original ground Depth of 20cm below the average elevation of original ground shall be under Site Clearing works Excavation below bottom of site clearing shall be applied to structure excavation Such elevation shall be shown on working drawing Marking elevation shall be provided prior to construction of cofferdam 7.2.2.2.2 Construction of Temporary Cofferdam shall be carried out in accordance with the construction sequence and approved working drawing Driving of steel sheet pile shall be under taken using the proposed equipment 7.2.2.3 Excavation 7.2.2.3.1 Revision A1, 23th Jul, 2010 Excavation shall be carried out layer by layer to have sufficient time for the installation and setting of wale and struts to support inside cofferdam Depths of excavation shall be carefully checked following page 19 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN the criteria and sequence for the construction of cofferdam as defined by design calculation Wale and struts shall be installed as shown on Working Drawing 7.2.2.3.2 Excavation on each layer shall be temporarily stopped below the elevation of the strut and wale in accordance with the design calculation and criteria of cofferdam Excavation shall only proceed to the next level after installation of wale and struts 7.2.2.3.3 In case the Excavation on the next level can not be carried out by Excavator located outside the cofferdam, an excavator shall be hoisted down inside the Cofferdam to carry out the excavation inside cofferdam Crane with Clamshell or Vessel shall also be used to hoist up the excavated materials 7.2.2.3.4 Excavated materials shall be removed immediately at the area to maintain space for the mobility of the equipments Excavated materials found to be suitable for backfilling shall be hauled to a designated stock pile area Unsuitable material shall be disposed as well to a designated waste area upon confirmation by the Engineer Pumping pit shall be provided at one or two corners A drain canal sloping towards the pumping pit shall be provided around perimeter of the excavation pit Drain shall be constructed outside the perimeter of the lean concrete Sufficient quantity of water pump shall be installed to prevent the accumulation of water inside cofferdam during excavation 7.2.2.3.5 7.2.3 Trimming and Base Leveling 7.2.3.1 When excavation reaches 20cm average above designed elevation of structure excavation, cutting of soil shall be done manually to avoid over cutting or over excavation Care shall be taken so as not to disturb the subsoil The base shall be compacted using a portable compacting machine or equivalent In cases that unsuitable material still exists at the designed bottom elevation of excavation, removal and replacement of such will be checked and confirmed by the Engineer If found to be unsuitable material it shall be removed and replaced 7.2.3.2 Revision A1, 23th Jul, 2010 After completion of excavation all loose and displaced material shall be removed, leaving a neatly and solid finished bed for the construction of footing or pile cap Limits shall be marked by survey stakes for setting up boundaries of the blinding stone, lean concrete and pile cap Completed Excavation shall be Inspected and Approved by the Engineer prior to construction of any permanent bedding or structure page 20 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Same procedure shall be done for base of box culvert and other structures 7.2.4 Blinding Stone 7.2.4.1 Establish limit of boundaries of blinding stone for setting side forms 7.2.4.2 Approved material for Blinding Stone shall be placed following the submitted working drawing The in-placed blinding stone shall be compacted thoroughly to the satisfaction of the Engineer using portable compacting equipment or equivalent At the area around the cast-in-place pile, a mechanical rammer or equivalent equipment shall be used in the compaction taking care not to damage concrete piles Tolerance on thickness and elevation shall be ±20mm 7.2.4.3 Completed blinding stone shall be inspected and approved by the Engineer prior to construction of lean concrete layer 7.2.5 Lean Concrete 7.2.5.1 Lean concrete shall be placed to the elevation, thickness as indicated on the working drawing and shall be cast within the defined boundaries by means of setting side forms Placing shall be carried out either by crane and concrete bucket and if necessary by concrete pump Tolerance on thickness and elevation shall be ±13mm 7.2.5.2 After consolidation and screeding to the correct plane and elevation, the concrete shall be floated to a smooth finish, the surface shall be free from depressions or projections The newly placed concrete shall be neatly finished and leveled to the design elevation as indicated on the working drawing Tolerance on thickness and elevation shall be ±13mm Pumping out of water shall be monitor and keep level of water so that the newly cast lean concrete will not be flooded until it is sufficiently set 7.2.5.3 Curing of lean concrete shall be carried out after completion of finishing Curing shall be done by spraying water or by covering the exposed surface with vinyl sheet 7.2.5.4 Compressive strength test specimen shall be taken from the lean concrete delivered to site Frequency shall be in accordance with Inspection and Test Plan Item 2.b 7.2.6 Pile Head Treatment Refer to GRBCC-MS-CIPCP-A2-EN (Method Statement for Cast-in-Place Concrete Piling 7.2.7 Construction of Substructure Revision A1, 23th Jul, 2010 page 21 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Method Statement shall be submitted separately 7.2.8 Backfilling & Compaction 7.2.8.1 Backfill shall be placed in layers of 15cm thickness when using mechanical rammer equipment for compaction However, when vibration roller equipment is available for compaction, backfill shall be placed in layers of 20cm Backfill shall be compacted to the satisfaction of the Engineer Whenever necessary, backfill materials shall be sprinkled with water to maintain the required moisture 7.2.8.2 Backfilling shall stop in accordance with design (minimum requirement) below the elevation of the wale and struts to give way for the removal and dismantling of support Backfilling shall continue after the removal of the struts 7.2.8.3 In cases that the area of Structure Excavation is under permanent roadway, such as Pipe Culvert and Box Culvert, backfill shall be carried out in accordance with Clause 3.11- “Protection of Structure”, Section 03400 – “Embankment construction” of the General Specifications and in accordance with Approved Method Statement for Road Earthwork GRBCC-MS-RE-A1-EN 7.2.8.4 Granular Backfill shall be placed behind Abutment and around pipe culvert and box culvert as shown on approved shop drawings Granular Backfill shall be placed in 15cm each layer up to the designed elevation Compaction shall be done using proposed compaction equipment up to 95% of the maximum dry density as determined by AASHTO T180 7.2.8.5 Backfilling shall be placed equally on both sides to the designed elevation or structures located in permanent embankment such as box culverts and pipe culverts Backfilling shall not commence until the concrete has not achieved sufficient strength 7.2.9 Extraction of Cofferdam Steel Sheet Piles used for cofferdam shall be removed and taken out using the proposed equipment Basically, all temporary cofferdams shall be removed unless otherwise it is required to remain Care shall be performed in order not to damage the in-placed structure 7.2.10 Cleaning Up Site Upon completion of backfilling, all excess materials and rubbish shall be removed and disposed to designated area, leaving the site neat and clean Revision A1, 23th Jul, 2010 page 22 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Quality Control The whole procedure shall be thoroughly checked by the engineer in charge for operation Refer to attached Inspection and Test Plan on Appendix III and attached Inspection sheet forms on Appendix IV Inspection sheet shall be subject to revision in accordance with the Instruction by the Engineer Safety Control “Safety Control Plan” shall be referred to approved project safety plan-GRBCC-PSP-A2-EN and shall be part of this method statement Prior and during the execution of Structure Excavation, basic safety precautions shall be implemented to work efficiently and to prevent any accident or casualties Prior to start the excavation & backfilling works, the following particular basic safety and precautionary matters shall be described and inform to all members working in the construction site in order to complete the excavation & backfilling work efficiently without any accident or casualty 9.1 Joint Meeting Prior to start any activity, a joint meeting with relevant staffs shall be held for the purpose of general explanation on the whole contents of works as well as mutual implementation of efficient work 9.2 Instruction All workers shall wear their Personal Protective Equipment (PPE) at all times, such as hardhat (helmet), gloves, safety shoes and working uniform 9.3 Prevention from downfall accident The surrounding perimeter of excavation shall be installed with a barricade, and a warning sign shall be install and provide Safety rails and ladders shall be installed at inside cofferdam Hauling equipment shall also be check prior to working Running speed of equipment shall be limited to prevent accident 9.4 Prevention of accidents by heavy machine Only skillful operator shall be permitted to operate the equipment on site In a case of new operators, a test of skill shall be performed first prior to his acceptance to the job Preventive maintenance check shall be done regularly at equipment working at site prior to full operation Stability of working area and foundation of equipment shall be thoroughly checked especially at locations of outrigger and track pad of cranes 9.5 Prevention of accident in the night shift works Revision A1, 23th Jul, 2010 page 23 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Sufficient numbers of lighting system shall be provided for the night shift works especially installed at working platforms If necessary all of the surrounding working area shall be lighted up 9.6 Prevention of accident of the falling objects During handling/hoisting of materials and equipment, it shall be tied-up properly to prevent from falling Lifting wire ropes shall be of designed capacity for heavy lifting Lifting wire of lifting equipment such as crane shall carefully check 9.7 Existing Facilities Existing facilities such as water line, overhead electric line, overhead telecommunication line and other facilities shall be check prior to Structure Excavation works Underground facilities shall also confirmed to related Authority to prevent damages during excavation If necessary excavation works shall be carried out to check existing underground utilities Care shall be considered not to damage existing facilities in the surrounding area during excavation 10 Environmental Control “Environmental Control Plan” shall be referred to approved project Environmental control plan - GRBCC-ECP-A2-EN and shall be part of this method statement Responsibility for surrounding environment shall be implemented during Structure Excavation Works and shall comply with the Condition of Contract and Vietnam’s National Law on Protection of Environment and other relevant legislation such as: Government Decree No.175/CP, Government Decree on providing Guidance for the Implementation of the Law on Environmental Protection, 1994 If any other problems occurred in the site, applicable counter measures or prevention action shall be considered immediately and executed as soon as possible Appendix I Revision A1, 23th Jul, 2010 page 24 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Typical Construction Sequence (Structure Excavation without Temporary Cofferdam) (4 sheets attached) Appendix II Typical Construction Sequence Revision A1, 23th Jul, 2010 page 25 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN (Structure Excavation with Temporary Cofferdam) (5 sheets attached) Appendix III Inspection and Test Plan Revision A1, 23th Jul, 2010 (2 sheets attached) page 26 GRBCC Noi Bai-Lao Cai Highway Construction Project Package A7: Km190+420 ~Km218+040 Method Statement For Structure Excavation GRBCC-MS-STEX-A1-EN Appendix IV Inspection Checklist Revision A1, 23th Jul, 2010 (4 sheet attached) page 27 ... Km195+137 A1, A2 A1, A2 P1 　 A2 A1 P2,P3,P4.P5 　 A1, A2,P1 P1.P2 　 A1. A2 P1 A1, A2 　 Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam... Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam... Km200+862 00 Method Statement For Structure Excavation GRBCC-MS-STEX -A1- EN Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam Without cofferdam