METHOD STATEMENT VRAMP – CONTRACT PACKAGE RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA DRAINAGE TABLE OF CONTENTS I CONSTRUCTION METHOD FOR PILE CULVERT, BOX CULVERT II DETAIL CONSTRUCTION[.]
VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA DRAINAGE PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA TABLE OF CONTENTS I CONSTRUCTION METHOD FOR PILE CULVERT, BOX CULVERT II DETAIL CONSTRUCTION METHOD FOR DITCH AND SURFACE DRAINAGE III DETAIL CONSTRUCTION METHOD FOR RELOCATION OF EXISTING IRRIGATION CHANNELS IV DETAIL CONSTRUCTION METHOD MANHOLES, INLETS, AND OUTLETS V CONSTRUCTION OF ROAD SIGNS VI IMPLEMENTATION OF ROAD MARKINGS VII SODDING FOR CATCH BASINS, VIII CONSTRUCTING MORTARED STONEWORK STRUCTURES PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA I CONSTRUCTION METHOD FOR BOX CULVERT Description This section described construction method for constructing new reinforced concrete pipe culverts, reinforced concrete box culverts, underpass box culverts and storm water drains This work shall include headwalls, inlet and outlet structures and reinforced concrete pipe cradles, as well as associated erosion and scour protection works The Contractor will build all of works in accordance with the Drawings and Specification and at the locations indicated by the Engineer Reference Standards 22TCN159-86 Specifications for construction and acceptance of precast reinforced concrete TCVN 9116:2012 Pre-cast RC box culvert Technical requirements TCVN 4453 – 1995 Monolithic concrete structure – Norm of construction and acceptance The construction of reinforced concrete box culverts, head walls, inlets, outlets and other reinforced concrete drainage structures shall be in accordance with the provisions of Section “Concrete and Concrete Structures” Material requirements 3.1 Concrete Concrete used for all structural work described in this Specification section shall be of the classes indicated on the Drawings and shall conform to the requirements specified in Section “Concrete and Concrete Structures” All finished surfaces of concrete, which are not permanently covered shall; have a smooth fair finish, be even and free from waves, be finished true to line/levels and contours, be free of blow holes, be free of honeycombing and air bubbles and the like Any holes left by bolts used to position the formwork shall be filled in with epoxy grout flush with the surrounding surfaces 3.2 Reinforcing Steel for Concrete All reinforcing steel used in the works shall conform to the requirements specified in Section, “Reinforcing Steel and steel works” 3.3 Bedding Granular material for bedding shall be in accordance with Paragraph 4.2, Table of Vietnamese Standard TCVN 7570-2006 and subject to the approval of the Engineer PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Lean concrete for bedding shall be class CIO bedding or blinding concrete in accordance with the requirements of Specification Section “Concrete and Concrete Structures” 3.4 Stone Masonry Stone Masonry and mortar used in the works shall conform to the requirements specified in Section “Stone Masonry” 3.5 Porous Backfill or Filter Material In case of requirement in drawings, Porous Backfill or Filter Material shall be in accordance with the provisions of Section “Porous drainage and Backfill” or as directed by the Engineer 3.6 Backfill Filling material used in the works shall conform to the requirements specified in section “Excavation and Backfill for structure” Detail construction method for box culvert 4.1 Preparation for construction The Contractor shall furnish shop drawings containing the constructions details for culverts and concrete drains indicated on the Drawings and as directed by the Engineer Shop drawings shall be submitted to the Engineer prior to the start of the construction of culverts and concrete drains Construction of culverts and concrete drains shall begin only after the Engineer gives approval of the shop drawings to the Contractor Temporary drainage work shall be in place and operating before beginning embankment works, or as directed by the Engineer No subgrade preparation or pavement overlay work (either in the road or the shoulder areas) shall commence until the culverts, headwalls, and other minor structures below the subgrade level along that particular section of the project are complete 4.2 Construct for Precast Concrete Elements Precast box culvert, precast bearing including box culvert 1.5x1.5m, 2x2m, bearing indicate in design drawings Reinforced Concrete Culverts shall be precast reinforced concrete class C25 and shall conform with Specification Section “Concrete and Concrete Structures” The precast box culvert shall be laid with male/female joints and reinforcement in all precast shall consist of steel cages with longitudinal bars all as indicated on the Drawings unless otherwise approved by the Engineer Bearings to support the precast shall be of the numbers and types indicated on the Drawings and subject to the approval of the Engineer They shall be of precast PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA reinforced concrete of concrete class C20 and shall conform with Specification Section “Concrete and Concrete Structures” No precast concrete products shall be cast until the Engineer has approved the manufacturing plant and the equipment therein The Contractor shall ensure that no damaged precast concrete items are taken to Site or installed on Site Damage is deemed to include, inter alia, honeycombing, chips, cracks and blemishes in appearance In the event the precast concrete items are damaged they shall be removed from the Site and never used in the Works No repairs or patching will be accepted by the Engineer whether the damage occurs on the Site or before or after delivery to Site The Engineer shall periodically inspect the precast concrete manufacturing plants to ensure compliance with the approved method statements for manufacturing The Contractor will supply material samples for laboratory testing to ensure quality compliance and will make the necessary arrangements to facilitate the inspections by the Engineer Such inspections shall include the inspection of reinforced precast concrete items All precast items shall be marked with a unique reference and no item shall be delivered to the construction Site without approval from the Engineer In order to maintain the quality of the precast concrete items the Contractor shall cast these in a factory off the Site Execution of concrete, reiforced steel, formwork comply with the requirements specified in section “Concrete and Concrete Structures” Execution order is described as followings: 4.2.1 Preparation of casting area: Units are casted in flat area, enough large to cast concrete and placing material The casting area is leveled and compacted to not be subside during casting and placing material as well as moving eqiupment and crane for installation units The casting area is reinforced with concrete, thickness of concrete layer 10-15cm 4.2.2 Preparation for material All material for executing units, design for component of concrete mixture must be approved by Project Manager prior to put in to use and comply with the requirements as indicated in article above – “Material requirements” 4.2.3 Reinforced steel works Reinforced steel is processed as Design Document which has been approved by Project Manager Steel is worked in to set for each culvert units Quantity of set for pouring concrete daily must be accepted by Project Manager prior to the start of the execute of concrete PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Reinforced steel works conform to the requirements specified in section TCVN 5709:2009 (Hot-rolled cacbor steel uses on construction) conform to the requirements as indicated section, “Reinforcing Steel and steel works” Installation of reinforced steel in to casting mould must ensure the requirement for thickness of protective concrete layer as specified in Design Document Use the trestle to control the thickness of protective concrete layer (if necessary) The trestle is made of material which assures the intensity and is similar colour to concrete and approved by Project Manager 4.2.4 Place and compaction of concrete: Concrete is mixed by mixer according to mix design approved by Project Manager Concrete need to tested the slump before placing, sampling under witnessed by Project Manager or authorized person After pouring concrete on formwork, will be compacted with specialized equipment These equipments operate inside the narrow formworks, ensuring not to displace the steel bars or trestle The vibrator equipments attach outer surface of formwork are encouraged to use Process of pouring and compacting concrete conform to the requirements specified in section “Concrete and Concrete Structures” 4.3 Construction of box culvert at the site 4.3.1 Construction plan and organization The positions of box culverts are for construction of service road; the service road contractor shall carry out construction of entire culvert length At the culvert positions that the service road or pipe culvert can not be constructed, the contractor shall ensure transport by construction of 1/2 the lower culvert first After that, the remained 1/2 culvert in the lower section shall be constructed; these culvert shall be strengthened and opened to its edges by disposed stone or gravel aggregate foundation The service road shall be large enough for directionally safe traffic movement The service road shall be arranged with sufficient signal posts, signal plate, lighting (at night) with traffic control staffs at ends continually during construction period Horizontal drainage culvert shall be arranged temporarily for not affecting the culvert construction activities as well as the existing discharge flow of the road, residential area and irrigational activities 4.3.2 Excavation of culvert trench Excavation of culvert trenches will execute conform to the requirements specified in section “Excavation and backfill for structure” Construction method and construction order as follows: - Located the centre of culver, scope of trenches as Design Drawings; PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA - Removal of old structures (if any); - Excavation of trenches by excavator, and using man-power for completing trenches Transporting waste material to regulated area - Excavation of trenches with enough large (500 mm minimum from road margin which around the culvert) in order to execute body culvert and embank both sides of culvert Slope of trenches will be executed comply with stability of trenches’s geology - Constructing culvert at the location where water flows frequently will be use cofferdam in method of constructing trenches It will be needed to construct a small ditch system around inlet to collection water and use pump to pump water out of trenches - When excavating to the trenches bottom, if the weak geological layer is found, the contractor shall inform the Engineer for on-time solution to keep progress - If the soil in the trenches is mixed with quarry stone then the over elevated excavated area shall be backfilled by materials of little deformation under pressure as sand, gravel sand or concrete with the same mark with the trenches and shall be in compact with the foundation The material type and compact requirements shall be in accordance with regulated design documents or with the instructions from the Engineer - Structures of blinding stone and concrete of culvert foundation will be only allowed install when trenches be executed as Design Drawings, be accepted by Project Manager 4.3.3 Installation of precast units The Contractor shall lay reinforced concrete cradles and pipes carefully The hubs or grooved ends shall be up grade The spigots or tongued ends shall be fully entered into the adjacent hub or groove and be true to the required lines and grades Before laying succeeding sections of reinforced concrete pipe which not require cambering, the Contractor shall plaster the lower half of the hub of the preceding sections on the inside with Portland cement mortar The mortar shall be sufficiently thick to bring the inner surface of the abutting pipes flush and even The Contractor shall plaster the upper half of the spigot of the succeeding pipe with mortar at the same time All Box Culverts shall be laid and fitted together such that the joint sealant forms a full and effective seal around the full circumference of the Box Culverts Joint sealants shall be placed such that any joints or overlaps in the sealant are at the top of the Box Culverts After laying the reinforced concrete pipe, the Contractor shall fill the remainder of the joint with sufficient mortar to form a bead around the joint The Contractor shall wipe PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA the inside of the joint and finish it to a smooth and even surface The mortar on the outside shall be cured and remain damp for two days or until the Engineer allows backfilling to proceed 4.3.4 Culvert Headwalls, Inlets, and Outlets Unless otherwise shown on the Drawings, the Contractor shall construct all culvert aprons, wing-walls, and headwalls using reinforced concrete of the class indicated on the Drawings and in accordance with requirements and provisions of section “Concrete and Concrete Structures” Scour protection works will normally be mortared rip-rap unless indicated in the Drawings 4.4 Construction of in-situ box culvert After constructing culvert trenches as described in article 1.4.3 (b), Work items for executing in-situ box culvert comply with order as follows: - Spreading blinding stone for culvert foundation; - Construction of bedding stone and foundation lean concrete; - Installation of reinforced steel, pouring concrete for bottom slab of body box culvert; - Installation of reinforced steel, pouring concrete for bodywall and face slab of culvert; - Execution of headwalls, wingwalls, structure of inlets, outlets - Execution of mortar stone structure, reinforcing slope of headculvert, reinforcing to unti – erosion of culvert downstream - Installation of over slab when filling soil to design elevation All works for executiong concrete, reinforced steel, formwork conform to the requirements specified in section “Concrete and Concrete Structures” Furthermore, these works need to comply with specific requirement as follows: Reinforcement erection in accordance with the design drawings The steel bars are discalced and cleaned Reinforcement connection methods as welding or binding shall be carried out right in accordance with regulations Reinforcement frames, fenders or rebars shall be laid on the skids; the cement skids have the similar thickness to the protection concrete thickness; the steel cable shall be lined in the skids to bind them on the reinforcement The skids laid on the suitable positions basing on the reinforcement density but not over 1m from a skidding place The salvage shall not be used to skid the outer surfaces of the structures Frame and fender of the reinforcement shall be binded tightly and not deflecting when installed in the platform and during concrete casting The pre-erected parts not affect to the parts erected afterwards The reinforcement installation shall be accepted by the SC before concrete casting PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Erection of the reinforcement platform: Before erection, the platform shall be cleaned and an anti-adhesive oil layer shall be applied The platform shall be erected by crane in cooperation with manpower and closely connected by bolts It shall be noted to erect the scaffolding and bearing braces to ensure the stability of the platform during concrete casting The cleats shall be arranged for easy disassembling of the scaffolding and platform when the concrete reaches the allowed strength Concrete casting and vibration: Equipments and materials as well as manpower shall be checked before concrete casting The materials shall be sufficient for continuous concrete casting and the concrete batching machine shall operate well - Concrete casting-in-situ shall be done by batching machine and crane Concrete shall be casted in the silo right after poured out from the batching machine Crane shall be used to take to concrete to right place - During casting, sample shall be taken to test the slump of the concrete for adjustment as in the design Sample shall be casted for later test The aggregate measurement system shall also be checked to ensure the design batching ratio for concrete - Concrete transference chute shall not be over dip, the free falling height of the concrete shall not be overt 1m because of making concrete stratification - The upper concrete layer shall be casted and vibrated before the concrete layer below starts to freeze - Concrete shall be well vibrated right after casted - If the needle vibrator and plate vibrator are used, then the maximum thickness of the concrete layer shall be as follows: If the needle vibrator is used, the concrete layer thickness shall be by 1.25 of the effective length of the needle arm If the plate vibrator is used, the concrete layer thickness shall be 12cm for the structure with much reinforcement, or shall be 25cm for the nonreinforcement structure The distance for needling the vibrator shall not exceed 1.5 time of the effective radius of the vibrator The vibrator shall not penetrate to the lower concrete layer casted before, if this layer is freezing - If the plate vibrator is used, then the vibrating marks shall overlapped by 5cm Vibrating through the reinforcement shall not be done - Concrete casting shall be done continuously until part by part of the construction works is completed Concrete maintenance: After concrete casting no later than 10 -12 hours in winter or - hours in summer, watering shall be done and the concrete surface shall be PHUONG THANH TRANCONSIN VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA covered in days and nights; if the temperature exceeds 150C, then watering shall be done in the first days and nights: in daytime, watering shall be done after every hours and in night time, watering shall be done for – times, then at least times of watering in a night is required Platform disassembling: Culvert wall platform (the non-load-resistant, non-strengthresistant structure) shall be disassembled when the concrete reaches the strength of minimum 25kg/cm2 For the strength-resistant scaffolding and platform, concrete shall reach 70% of the designed strength then the platform can be disassembled The platform disassemble shall be done carefully for not creating the thrust to the concrete structure Before and after strength-resistant platform disassemble, the slump of the deformation area and structure shall be measured 4.5 Backfill Backfill of foundation pit and fill material both side of culvert comply with the requirements specified in Section “Excavation and backfill for structure” The Contractor shall not backfill any pipe until the Engineer inspects and approves the site conditions The Contractor shall backfill and compact the soil around and over the reinforced concrete culvert pipes in accordance with the requirements specified in Section “Embankment Construction” and “Excavation and backfill for structures” The Contractor shall take the fill to a minimum height of 500 mm above the top of the pipe Unless in a trench, the fill shall extend for a minimum distance of one and a half diameters from the centerline of the pipe on each side of the pipe The Contractor shall take special care to compact the backfill under the haunches of the pipe properly The backfill shall be brought up evenly on both sides of the haunches for the entire pipe length Heavy earth moving and compacting equipment shall not operate closer than 1.5 meters from the culvert until the cover above the pipe is at least 500 mm Light weight equipment may operate within the limitation mentioned above provided the backfill is placed and compacted at least 300 mm above the top of the pipe Notwithstanding these conditions, the Contractor shall be responsible for and shall rectify any damage resulting from such operations 4.6 Cleaning Culverts The Contractor shall clean all culverts until they are free of loose debris, soil, and all foreign material The Contractor shall keep the culverts clean and maintain them in an operating condition throughout the Contract Period The Contractor shall only permit water to flow through the cleaned culvert after the Engineer inspects and approves the culvert II CONSTRUCTION METHOD FOR DITCH Description PHUONG THANH TRANCONSIN 10 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA This work shall consist of furnishing, constructing and/or installing side drainage types of structures built, slope drainage types of structures built in conformance with the Contract Drawings Included are such items as trapezium shaped, rectangle shaped, and bench ditch, stepped drop, ditch at top of slope Materials requirement To construct roadside Ditches using mortared stonework, concrete, reinforced concrete, or precast concrete as shown on the Drawings or directed by the Engineer The Contractor shall submit to the Engineer, for his approval, details and samples of materials he intends to use for the construction of Ditches 2.1 Bedding: Granular material for bedding shall be in accordance with Paragraph 4.2, Table of Vietnamese Standard TCVN 7570 - 2006 and subject to the approval of the Engineer Lean concrete for bedding shall be class C10 bedding or blinding concrete in accordance with the requirements of Specification Section “Concrete and Concrete Structures” 2.2 Mortared Stone: Mortared stonework shall conform with the requirements of Specification Section “Mortared Stonework” 2.3 Concrete: Precast and cast in situ concrete for side drainage structures, shall conform to the requirements of section “Concrete and concrete structure” 2.4 Reinforcing Steel for concrete: All reinforcing steel shall conform with the requirements specified in Specification Section “Reinforcing Steel” 2.5 Rip-rap: Rip-rap for side drainage structures shall conform to the requirements of section “Mortared Stonework” Method of Construction 3.1 Site Preparation Drainage excavation is combined with embankment excavation, and then the drainage form shall be fixed manually Drainage before construction shall be cut off with abundant soil, the jumping compactor shall be used to compact the drainage bedding, assuring the gradient, compactness and the flat of the slope and drainage groove in conformity with the design PHUONG THANH TRANCONSIN 11 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Positioning for pipe driving and line stretching to create the form and limited surface, in parallel with the flat surface, shall be carried out Drainage foundation excavation shall conform to the requirements of Section “Excavation and backfill for structure” 3.2 Construction side drainage concrete Construction side drainage concrete, shall conform to the requirements of section “Concrete and concrete structure” Basic construction order as follows: 3.3 - Construction of ditch bottom slab; - Installation of formwork of ditch border, pouring concrete as design; - Removal of formwork, completing the ditch as design - Supplementary embankment of ditch structure (if any) - Clearing and removing of waste material Construction bench ditch, ditch at top of slope Construction bench ditch concrete, ditch at top of slope concrete, shall conform to the requirements of section “Concrete and concrete structure” Supplying concrete to construction location, transporting to bench ditch, top ditch by capstan system or hoist Basic construction order as follows: 3.4 - Constructing of ditch bottom slab; - Installation of formwork of ditch border, pouring concrete ditch as design; - Removal of formwork, completing the ditch as design - Supplementary embankment of ditch structure (if any) - Clearing and removing of waste material Construction stepped drop by stone masonry Rip-rap and mortar for stepped drop structures shall conform to the requirements of section “Mortared Stonework” Supplying riprap and grouting (mortar) to construction location by capstan system or hoist Preparation for foundation pit of stepped drop accordance with design document Executing mortar stone of stepped drop in process from low to upper All joints of inlets from bench ditches, top ditches, side ditchs, executing carefully the inlet of culvert and comply with Design Drawings Ensuring in good operation PHUONG THANH TRANCONSIN 12 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA III DETAIL CONSTRUCTION METHOD FOR CATCH BASINS, MANHOLES, INLETS, AND OUTLETS Description This Specification Section prescribes the requirements for the construction of Catch Basins, Manholes, Inlets and Outlets to culverts Requirement Materials The Contractor shall submit to the Engineer for his approval details and samples of materials he intends to use for the construction of Catch Basins, Manholes, Inlets and Outlets to culverts and ditches included in the Specification 2.1 Bedding Fine sand fill/bedding shall be black sand complying with the requirements of Table of Vietnamese Standard TCVN 7570-2006 with a fineness modulus of 0.7 to 2.0 Organic and other impurities shall be in accordance with Table of Vietnamese Standard TCVN 7570-2006 as follows: - Clay and balled impurities shall be less than 0.5% - Muds and dirt shall be less than 10% It will not be necessary to determine the alkali reactivity or the chloride content of the sand for this use Sand shall be sampled and tested in accordance with Vietnamese Standard TCVN 7572-2006 (Aggregates for concrete and mortar - Test methods) Granular material for bedding shall be in accordance with Paragraph 4.2, Table of Vietnamese Standard TCVN 7570-2006 and subject to the approval of the Engineer Lean concrete for bedding shall be class C10 conforming with the requirements of Specification Section “Concrete and Concrete Structures” 2.2 Concrete Concrete used for all structural work described in this Specification section shall conform to the requirements specified in section “Concrete and Concrete Structures” 2.3 Reinforcing Steel for Concrete All reinforcing steel used in the works shall conform to the requirements specified in section, “Reinforcing Steel and steel works” 2.4 Mortared stone Mortared stone and mortar used in the works shall conform to the requirements specified in section, “Mortared stone” 2.5 Steelwork PHUONG THANH TRANCONSIN 13 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Steelwork items shall comply with the requirements of Vietnamese Standard 22TCN288-2002 and shall be galvanised in accordance with AASHTO M232 2.6 Brickwork Brickwork shall conform with the requirements of Specification Section “Brick Masonry” 2.7 Mortar Mortar for joints or other works shall only be used if required by the Engineer, or so indicated on the Drawings If or when required mortar shall conform with the requirements of Specification Section “Cement Mortar” 2.8 Steel Grating Steel grating covers for the Catch Basin for Median as indicated on the Drawings shall comply with the requirements of AS 3679 Grade 250, BS 4360 Grade 43A or ASTM A36 2.9 Porous Backfill or Filter Material In case of requirement in drawings, Porous Backfill or Filter Material shall be in accordance with the provisions of section “Porous drainage and Backfill” or as directed by the Engineer 2.10 Backfill Filling material used in the works shall conform to the requirements specified in section “Excavation and Backfill for structure” Detail construction method for catch basins, manholes, inlets, and outlets 3.1 Shop Drawings and Schedule 3.1.1 Shop Drawings: The Contractor shall prepare shop drawings and method statements showing his proposed construction details for the Catch Basins, Manholes, Inlets and Outlets to culverts and ditches indicated on the Drawings or as directed by the Engineer Shop drawings and method statements shall be submitted to the Engineer for his approval prior to the start of the any construction works, including the start of any precast works 3.1.2 Work Scheduling: Construction of the Catch Basins, Manholes, Inlets and Outlets to culverts and ditches shall not begin until the Engineer has approved the Contractor’s shop drawings and method statements The Contractor shall allow sufficient time in his program me for the submission and approval of his shop drawings and method statements and for any revision and resubmission of such documents that may be required to incorporate the comments of the Engineer PHUONG THANH TRANCONSIN 14 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA 3.1.3 Site Preparation The Contractor shall carry out any excavation that may be required for Catch Basins, Manholes, Inlets and Outlets in accordance with the requirements of Specification Section Structural Excavation The Contractor shall be responsible for all dewatering and temporary support works for the excavations and all other necessary temporary works that may be required during construction 3.2 Delivery, Storage and Handling Materials delivered to Site shall be inspected for damage, unloaded, and stored with minimum handling Any damaged materials shall be rejected and replaced at the Contractor’s expense 3.3 Connections Culvert pipes or ditch sections shall be placed or cast and properly bedded before being cast into or built into Catch Basins, Manholes or Inlet and Outlet structures 3.4 Manhole and Catch Basin Covers, and Frames Covers (R.C or Steel Grating) to manholes and catch basins shall be fabricated, precast or prefabricated, supplied and installed complete with steel frames and lifting points as indicated on the Drawings IV V IMPROVEMENT OF EXISTING DRAINS AND DRAINAGE STRUCTURE General Such work may include the addition of additional drainage lines and structures to existing drainage systems, the modification of existing draining structures and/or the cleaning of existing drainage lines and catch basins in accordance with drawing requirements and/or as required by the Engineer The materials for improvement of existing drains and drainage structures shall conform to the requirements specified in respective sections for materials of each type of existing drain or structure that will be improved In the event that the existing drain or structure is of a type that is not covered by the Specification, the material requirements shall conform to the Viet Nam Standards, or to be as determined by the Engineer The Contractor shall furnish Shop Drawings containing the construction details for improvement of existing drains and drainage structures indicated on the Drawings and as directed by the Engineer Shop drawing shall be submtited to the Engineer for the approval The Contractor shall not begin the improvement of drains and drainage structures work without the Engineer’s approval on the schedule and construction method proposed by the Contractor PHUONG THANH TRANCONSIN 15 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA Modifications and improvement of existing covered concrete drainage ditches Where indicated on the drawings and/or as required by the Engineer the Contractor shall execute the works for some or all of the following modifications to existing covered concrete drainage ditches: 2.1 - Extending the top elevation of exiting drainage ditches to accommodate revised sidewalk and or roadway elevations; - Removing and replacing existing concrete ditch covers; - Providing and installing new concrete ditch covers; - Removing existing cross drains and catch basins; - Installing new cross drainage piping and catch basins; and/or - Cleaning of existing concrete ditches Extending elevation of existing concrete ditch structures As required to extend the wall height of an existing drainage ditch, the Contractor shall remove necessary concrete, plaster, blocking Unless otherwise required by the Engineer, the Contractor shall extend the height of the drainage ditch walls to the required new elevation using materials similar to those employed on the original wall Unless otherwise required: 2.2 - Stone and or block shall be similar to those used for the original wall, subject to the approval of the Engineer - Wall plaster, if required, shall be proposed by the Contractor and subject to the approval of the Engineer - Concrete used shall be Class c in accordance with Specification section “Concrete and Concrete Structures”; moreover, concrete work shall also be in accordance with provisions of Specification - Concrete reinforcement, if required, shall be in accordance with the provisions of Specification section “Reinforcing Steel” - Mortar shall be in accordance with the requhements of Specification Concrete drainage ditch covers All existing concrete drainage ditches to be modified and/or cleaned shall be inspected by the Engineer to determine the acceptability of existing concrete ditch covers and the need for additional and new covers At this time the Engineer shall advise the Contractor what concrete covers shall be reused, the units that shall be replaced and the requirements for new cover sections PHUONG THANH TRANCONSIN 16 VRAMP – CONTRACT PACKAGE:RAP/CP15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA In accordance with the reqmrements determined by the Engineer, the Contractor shall provide new sections of precast concrete ditch covers similar in appearance, thickness and dimension to the existing concrete covers Unless otherwise determined by the Engineer, the concrete used for shall be Class c in accordance with Specification section “Concrete and Concrete Structures” Concrete works shall also be in accordance with provisions of Specification Concrete reinforcement shall be in accordance with the provisions of Specification 2.3 New cross drainage piping and catch basins In accordance with drawing requirements or as required by the Engineer the Contractor shall remove existing concrete cross drainage ditches and/or catch basins, and replace that with new cross drainage piping and/or new catch basins After removal of existing structures, and prior to the construction of new structures, the Contractor shall prepare the subgrade by removing all loose materials and thoroughly compacting the subgrade material as established in Specification Backfill materials if required, shall be in accordance with Specification, unless otherwise approved by the Engineer Drainage piping connections to existing concrete drainage channels shall be accomplished by using existing drainage ditch openings in the drainage channels as much as practicable The Contractor shall extend existing openings in existing drainage ditch walls or provide new connection openings as required to provide proper new cross drainpipe placement New cross drainage piping shall extend at least one (1) cm past the inside face of the existing drainage channel The Contractor shall fill areas around pipe openings in the drainage channel walls with mortar in accordance with provisions of Specification section “Cement Mortar” Where the removed drainage ditches opening extends to the top of the existing drainage channel wall, the wall section above the drainage pipe shall be installed in accordance with requirements of this Specification 2.4 Cleaning of existing drainage ditches and drains As indicated on the drawings or as duected by the Engineer, the Contractor shall remove all debris and obstructions from existing drainage ditches, cross drains and/or catch basins Such work for cleaning shall include the removal of all debris and obstructions from open as well as covered drainage structures to the satisfaction of the Engineer PHUONG THANH TRANCONSIN 17 ... otherwise approved by the Engineer Drainage piping connections to existing concrete drainage channels shall be accomplished by using existing drainage ditch openings in the drainage channels as much as... precast bearing including box culvert 1.5x1.5m, 2x2m, bearing indicate in design drawings Reinforced Concrete Culverts shall be precast reinforced concrete class C 25 and shall conform with Specification... PACKAGE:RAP/CP 15 – MAINTENANCE OF NH6 FROM KM193÷KM233 IN SON LA This work shall consist of furnishing, constructing and/or installing side drainage types of structures built, slope drainage types