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4 Construction works Scale of construction work of water supply system in Thanh Thach commune, Tuyen Hoa district, capacity 400 m3day 4 1 Inlet construction work The inlet and pumping station level I. The raw water pipeline is responsible for transporting water from the dam to the treatment plan. Design 01 raw water pipeline from the foothill (at elevation +35.70m) to the water treatment plant located in the high hill area (the location of the treatment cluster is at the elevation of +65.50m). Raw water pipeline design with working capacity 400 m3day. The treatment plan works 2024h, so the raw water pipe works 2024h with 1 mode.
4 Construction works Scale of construction work of water supply system in Thanh Thach commune, Tuyen Hoa district, capacity 400 m3/day 4.1 Inlet construction work The inlet and pumping station level I (raw water pumping station), capacity 20 m3/h, located in Gianh river, the foothill area, 60m from the construction site of the water plant Building elevation +35.70m; pit structure by M250 reinforced concrete Install 02 submersible pumps operating alternately 20/24 hours, supplying water to the treatment cluster at the water plant area 4.2 Raw water pipeline: a) Design plan: The raw water pipeline is responsible for transporting water from the dam to the treatment plan Design 01 raw water pipeline from the foothill (at elevation +35.70m) to the water treatment plant located in the high hill area (the location of the treatment cluster is at the elevation of +65.50m) Raw water pipeline design with working capacity 400 m3/day The treatment plan works 20/24h, so the raw water pipe works 20/24h with mode - Flow: Q= 20m3/h - Velocity: (0,8-2,0) v=1.2m/s - Required pipe cross-section: F=Q/(v*3600)=30/(1.2*3600)=0.00463 m2 - Pipe diameter: d=sqrt(4F/3.14)=sqrt(4*0.00595/3.14)=0.0768m Choose pipe with diameter: d=80mm Design diameter of HDPE pipe –D90 going on above road Pipe sections buried directly in the ground use HDPE pipes to reduce investment costs b) Hydraulic calculation of raw water pipeline: - Water plant capacity: 400 m3/day - Operating time t=20h - Flow of pump: 20m3/h=0.005556 m3/s - Hazen Williams coefficient: C=140 Unit loss: i=6.824*(v/C)^1.852*D^(-1.167)=0.0193 1000i=19.3m/km Raw water pipe length: 60m Loss along the pipeline: Hdd=19.3*0.06=1.158m Local loss: Hcb=v2/2g*C=1.5m Residual pressure at treatment system: 6m Level difference: 40m Required pump head: 48.658m Choose Hđ=50m 4.3 Cluster of Mixing tank, cylindrical vortex reaction tank, vertical settling, rapid filtration: The treatment system with a capacity of 400m3/day includes: 4.2.1 Static mixer The requirement is that the static mixing has enough strength to mix chemicals, ensuring that the chemicals are evenly dissolved in the raw water before being distributed to the filter settling cluster, avoiding the uneven mixing of chemicals leading to effective low processing, wasted chemical consumption Static mixer equipment is designed with the following parameters: - Dimension DxH: 150x1000 mm; - Material: Inox SUS 304; - Connection by flange BS4504 DN80; - Hydraulic loss: 0.06 meters of water; - Mixing intensity is 460 gradient (make sure the mixing intensity is in the range of 200-1000 gradient); 4.2.2 Lamella settling tank Lamella settling tank has an operating capacity of 20m3/h According to article 6.66 and formula (6-9) TCVN 33-2006, the horizontal area of the settling tank is calculated according to the following formula: F q (m ) a In which: - q: Flow of water in m3/h q = 20 m3/h - a: Surface load of the settling tank for less turbid water is taken from 3-3.5 m /m h; for medium turbid water taken from 3.6-4.5 m3/m2.h and for more turbid water from 4.6-5.5 m3/m2.h Choose a= 4.5 m3/m2.h F = 20/4.5 = 4.44 (m2) Lamella settling tank is designed in a circular cross-section The tank diameter is: Dtank = sqrt(4*4.44/π) = 2.38 (m) Choose a tank diameter of 2.4m The settling tank height includes the sludge reservoir height, the suspended sediment height, the lamellar sediment height, the safety water layer height and the vortex reaction height The height of the settling tank is 6.4m - Dimension of settling tank: DxH=2.400x6.400mm - Material: SS400 steel with layers of epoxy coating - Accompany with: + Lamella settling plate, water collection trough + Railing, galvanized steel SS400 working floor 4.2.3 Self-cleaning Gravity Filter Design capacity of treatment system: 20 m3/h The required filter tank area is: V = 20/8 = 2.5 m2 Choose a fast filter tank filtration speed v = m/h The filter sand layer thickness is 0.6-1mm To increase structural durability and conform to technology, choose a round cylindrical tank The required diameter of the tank is: V = 3.14 * D2/4 => D = 1.78m The thickness of the filter material layer is 1-1.2m (according to section 7.8 "Book of water treatment for domestic and industrial use" - Trinh Xuan Lai) Choose h = m The volume of filter media layer is: V = 1*1.8*1.8*3.14/4 = 2.54 m3 Volume of sludge container Vsludge = 38% Vfilter = 0.96 m3 The height of the filter is: H = 0.45 + 1+ 1.05+2.0 = 4.5 m In which: - Height of the bottom of the filter floor: 0.45 meter - Height of filter sand layer: meter - Safe water layer height Backwash water tank: 1.05+2= 3.05 meter - Dimensions of open backwash gravity filter tank with siphon: DxH = 1,800x4,500 mm - Material: SS400 steel with layers of epoxy coating - Accompany with: + Filter cap, filter sand + Railing, galvanized steel SS400 working floor Calculation of the filtering process Backwash tank volume Vbackwash= x (1.8x1.8x3.14/4)= 5.1 (m3) Filter media size: 1-2 mm, heterogeneity factor is 1.5 mm Rinse the filter with water stored on the backwash tank When washing the filter, there is water on the surface washing water intensity is 6-8 m 3/m2.h (according to section 7.8 "Book of water treatment for domestic and industrial use" - Trinh Xuan Lai) Washing time minutes The volume of water to be washed and filtered is: Vwash= 2.54 *6*5*60/1000 = 4.57 (m3) From the above we have Vbackwash ≤Vwash So the device meets the filter washing process - The filter settling system is protected in SS400 steel structure, 3-layer epoxy coating - Output water after treatment meets QCVN 01:2009/BYT National Technical Regulation on drinking water quality and QCVN 02:2009/BYT National Technical Regulation on domestic water quality 4.4 Chemical house, combined with operator shift: The chemical house is a place to dosing and mixing chemicals in the process of settling, filtering and disinfecting water The items in the chemical house include: a) Chemical coagulant PAC - PAC mixing tank: 01 plastic tank, tank capacity: Wh = 0.5 (m3) - SUS 304 stainless steel stirrer: 01 set - Mixing device: stirring motor Power N = 0.75 kW + Select the number of rotations of the propeller: 30 rpm + Propeller length is taken as: 0.45 x d = 0.45 x 0.8 = 0.36 (m) - Dosing device: Dosing pump + Flow of pump: 28 l/h + Head pressure: H=30m + Power 14W b) Chemical flocculation: polymer - Polymer mixing tank: 01 plastic tank, tank capacity: Wh = 0.5 (m3) - SUS 304 stainless steel stirrer: 01 set - Mixing device: stirring motor Power N = 0.75 kW + Select the number of rotations of the propeller: 30 rpm + Propeller length is taken as: 0.45 x d = 0.45 x 0.8 = 0.36 (m) - Dosing device: Dosing pump + Flow of pump: 28 l/h + Head pressure: H=30m + Power 14W - Chemical warehouse + Chemical reserve is about 3.00 tons/15 days + Warehouse floor area: 1.98m2 b) Chlorine disinfection: Disinfect water with liquid chlorine Expected chlorine dosage is 1-3g/m of water; On days when the water supply system is in normal operation, the dose of 1g/m3 is used When there is an epidemic or when cleaning pipes, use the dose of 2g/m3 The capacity of chlorination is calculated by the formula: P = Q * CLmax = 20 * = 40 g/h Q: Treatment water flow, Q= 20 m3/h; CLmax: The largest amount of chlorine added to the water, CLmax = 2g/m3 Amount of chlorine used for day: M = 400*2/1000 = 0.8 kg/day With the amount of Active Chlorine needed in one hour: 33.33g/h Disinfectant chlorine injection system includes: - The metering pump has Q = 28 l/h 3Bar pressure; P=14W Including 02 machines: 01 active machine and 01 standby machine - 500ml composite tank - Stirring motor - SUS 304 stainless steel stirrer: 01 set The chemical house is built at the windward end to store chemicals and install equipment for mixing and dosing chemicals The chemical house has a water supply, electricity supply and ventilation system The size of the chemical house is 7.8m*11.4m, 3.6m high Reinforced concrete floor frame, brick wall with only XM grade 75 mortar The roof floor is poured with reinforced concrete, tiled with heat-resistant bricks and covered with Xika waterproofing layer Finished ceramic tile floor Arrange water supply and drainage systems, daily-life electricity supply, synchronous lighting In the chemical house, 01 room is arranged and there is a separate toilet area to place control cabinets and staff on duty 4.5 Clean water tank: a) Calculation of tank capacity: The capacity of the clean water tank is determined according to the working mode of the raw water pipeline of the level pump Raw water pipe works of raw water pipes 24/24 hours a day with a regime of 4.17% Qday Level pump is fitted with a frequency converter, so the mode is controlled according to the water demand of the water supply network Graph of water demand for the corresponding water supply network K hour = 1.8 % Q day Time/day Calculation table of tank capacity Hour of day Tank Network water Tank inlet Raw water pipe outlet consumption flow flow (%Q) flow (%Q), Khour=1,6 (%Q) (%Q) Water flow in tank (%Q) 0-1 4.17 0.80 3.37 7.39 1-2 4.17 0.80 3.37 10.76 2-3 4.17 0.80 3.37 14.13 3-4 4.17 0.80 3.37 17.50 4-5 4.17 2.10 2.07 19.57 5-6 4.17 4.30 0.13 19.44 6-7 4.17 6.10 1.93 17.51 7-8 4.17 6.20 2.03 15.48 8-9 4.17 4.70 0.53 14.95 9-10 4.17 5.40 1.23 13.72 10-11 4.17 5.50 1.33 12.39 11-12 4.17 6.20 2.03 10.36 12-13 4.17 4.10 0.07 10.43 13-14 4.17 3.80 0.37 10.80 14-15 4.17 4.00 0.17 10.97 15-16 4.17 5.80 1.63 9.34 16-17 4.16 6.20 2.04 7.30 17-18 4.16 6.40 2.24 5.06 18-19 4.16 6.70 2.54 2.52 19-20 4.16 5.80 1.64 0.88 20-21 4.16 4.80 0.64 0.24 21-22 4.16 4.40 0.24 0.00 22-23 4.16 2.60 1.56 1.56 23-24 4.16 1.70 2.46 4.02 Total 100.00 100.00 - Storage tank capacity: Wstorage tank = (Qday max ) x (19.57% + 4% backup) = (520 )*23.57% = 122 m3 - Water reserve capacity for the treatment plan of the tank and other factors: Wtreatment plant = 20 m3 Total storage tank capacity calculated: Wtank = Wstorage tank+ Wtreatment plant = 122 + 20 = 142 m3 Design tank capacity 150 m3 b) Design plan of storage tank: The tank is designed with the size of 10.0 m x 6.0 m, the height of 3.0 m The tank is placed semi-submersible, designed with reinforced concrete- M250 with 250mm thick wall, 250mm thick M250 crushed stone BT bottom, 150mm thick reinforced concrete-M250 lid, a layer of soil 30cm thick on the top of the tank strip, planting insulation grass 4.6 Sludge drying bed The water and sludge from the settling tank and filter discharged into the water source are taken to the sludge drying kept in the sludge drying bed, the water is discharged into overflows and self-infiltrates into the soil after being treated sludge drying bed is designed with compartment tank before being bed The sludge is the water source, satisfactorily The - Basic size of each compartment: LxB = 6.6x15.00m - Surrounding wall structure: 300 thick stone masonry, brick wall, concrete slab bottom 4.7 Power supply for Treatment plant: 4.7.1 Design basis Use those normative standards outlined in the Framework and in the list below: - TCXDVN 46:2007: Grounding and lightning protection standards for houses and buildings - TCXDVN 394-2007: Standard for installing electrical cables in construction works - 11 BC (18:21)-2006 Regulation on electrical equipment - TCVN 4086-95 Electrical safety in construction - System of international standards: (IBC, IEC, BS, EIA, IEE, NEC, ) 4.7.2 Calculation of required load a - Lighting calculation formula: E = (lux) In which : E : The illuminance of the lamp : The luminous flux of the lamp S : Area of use With average illuminance on the plane from 100-300 (lux) b - Formula for calculating power and wire cross-section: Calculating capacity according to the number of equipment installations and rated power: PTT = In which : Ptt: Calculated power Kđt:Simultaneous factor (select Kdt = 0.7-0.85 according to the property of the sub-load) n: Number of devices that are the same Pđm : Rated power of the device c Formula for calculating current consumption: * Single phase voltage: * phases voltage: In which : 10 avoid long-term accumulation of gas at those piles, reducing the cross-section of water pipes and causing real gas phenomena to destroy the pipeline network According to the topography, at the position of turning the slope from the top down, place the air release valve and the bottom turn up, place the sludge discharge valve The exhaust valve is located near the locations where the discharge water can be received Install tee and valves to connect and operate safely and continuously Arranged along pipeline routes; Used to protect valves Valves with DR < φ60 use brass threaded valves; Valves with condition >= φ60 use flanged gate valve AVK; Valve pit poured concrete stone 1x2, M200, reinforced concrete cover grade 200 Construction solutions, safety and site clearance plan 5.1 Construction solutions Thanh Thach commune's clean water supply system is a project of social infrastructure, it is necessary to have an aesthetic architecture to create a beautiful landscape with orientation for the future, stimulating the desire to use of the local people, ensuring the environment In terms of land use: Use the land fund rationally and economically to avoid waste Specifically, the land recovered to build the water plant is the land for planting production forests managed by the Commune People's Committee In terms of architecture: Reasonable layout of premises to avoid negative impacts from residential activities, neighboring livestock production, as well as the opposite impact Avoid affecting the sustainability of surrounding works, such as: passing roads, drainage system of adjacent production areas and people's activities The construction area of the water plant has a relatively good soil mechanical structure, so the cost of foundation construction is reduced The buildings are built of reinforced concrete, to increase the sustainability and stability The leveling of the water plant is suitable to the planning elevation and the current natural terrain, the leveling area is suitable for each construction phase 19 Construction of the pipeline saves the maximum amount of excavation and backfilling, the sections with suitable terrain apply mechanization to speed up the construction progress and reduce investment costs 5.2 Safety in construction 5.2.1 When building the foundation Before building the foundation, it is necessary to check the condition of the soil wall and the soil wall support system (if any) to see if there are any signs of unsafety that must be corrected immediately Pay special attention to digging holes where the soil is loose, wet, near roads under the impact of vehicles Check to see if on the edge of the pit, excavated soil, construction materials and construction equipment can cause landslides Check to see if on the edge of the pit, excavated soil, construction materials and construction equipment can cause landslides Along the foundation pit, there must be an empty strip of land at least 0.5m, on which construction materials and machinery must not be loaded Put bricks into the foundation pit with a slide board, put mortar with an inclined board - During construction, if the foundation pit is flooded due to rain or groundwater, measures must be taken drainage, when the pit is dry, the construction will continue - When backfilling the foundation pit, it must be filled evenly on both sides, filling up to where compacted soil 5.2.2 When building the wall - Before building a wall, it is necessary to check the condition of the foundation or the pre-built wall as well as the condition of the means of working at height such as: Scaffolding, check the arrangement of materials and the position of the workers - When building a wall with a height of less than 7m, a barrier must be made on the human side along the perimeter of the work 1.5m from the wall to prevent tools and materials from falling on people's heads - The holes in the wall from the 2nd floor and above must be covered if those holes can be passed through 20 - Do not stand on the wall to build, not lean on the ladder against the newly built wall to go up and down - When lifting materials, lifting equipment such as hoists, winches, and cranes must be used - Do not throw bricks and tools from above to the ground - Equip workers with full protective equipment such as shoes, plastic hats, safety belts, gloves and boots - Do not dump construction waste indiscriminately on the ground, especially in residential areas, cause polluting the environment Construction humus must be concentrated in one place to be transported to the designated landfill - Workers working with cement or sand screening must wear masks to avoid inhaling dust affecting their health - Regularly disseminate regulations on occupational safety and labor discipline to workers, keep a log of training sessions on occupational safety and health for workers - Workers working at height must ensure good health and not get dizzy - Prohibit the use of alcohol while working - Scaffolding must be installed firmly, braced stably, with guardrails It is forbidden to erect brick or stone scaffolding columns 5.2.3 When constructing the water supply pipeline a Construction methods and construction time: During the construction process, the unit strictly implements the agreed measures and construction time, must ensure smooth and safe traffic according to regulations and must not cause damage to existing road works b Arrange signs, barriers, baries, signal lights, lights to ensure traffic safety on the construction route Fully arrange traffic safety system such as road signs, barriers, baries, signal lights, warning people in accordance with the provisions of the National Technical Regulation on road signs (QCVN 41:2012) /BGTVT) c Material collection arrangement 21 - Construction materials are mainly gathered in the construction site yard with tarpaulin to cover the rain, only during construction will they be transported to the construction site - Bring to the scene all kinds of construction materials and materials for a certain item and get enough in working shift, neatly arranged in the fence class within the construction scope - Arrange materials so that they are easily identifiable and neat, tidy and reasonable for construction and transportation - Construction materials are only brought to the site enough to use from two to three construction sections and the length so that the materials not extend more than 100m Materials must be placed on one side of the road, not parallel to both sides, which narrows the ground and road surface - Before the flood, it is necessary to complete construction, remove all excess materials on the road and have a plan to ensure traffic safety in case of accidents caused by rain and floods within the assigned construction site The contractor must make a plan to ensure traffic safety and send it to the local road management unit for coordination - It is strictly forbidden to spread materials that obstruct traffic or flow to the road surface, causing slippery, unsafe traffic and environmental pollution, or burning asphalt on roads in densely residential areas 5.3 Fire prevention 5.3.1 Requirements for fire prevention - Fire prevention measures must be applied to minimize the possibility of fire In the event of a fire, it is necessary to detect the fire quickly in order to save it in time to prevent the fire from spreading to other areas, creating a large fire that is difficult to cure, causing serious consequences - Fire prevention measures must ensure that when there is a fire, people and assets in the building can easily evacuate to safe areas as quickly as possible - In any condition, when a fire occurs in a fire-prone location in the building, it must be detected immediately at the place where the fire is generated in order to organize timely rescue 22 5.2.3 Requirements for fire fighting Fire fighting equipment of the works must meet the following requirements: - Fire fighting equipment must be ready in standing mode, when a fire occurs, it must be used immediately - Fire-fighting equipment must be suitable and effective for fighting fires that may occur in the building - Fire fighting equipment equipped for works must be easy to use, suitable for works and conditions of country - The main equipment must have technical parameters that meet the standards of Vietnam, standards of advanced countries - Fire fighting equipment must be fire fighting type that does not damage other tools and equipment in secondary damage fire fighting areas - Equipped fire protection system equipment must ensure minimum investment conditions but maximize efficiency The original fire fighting vehicle used portable fire extinguishers MFZ4, CO2MT3 gas cylinders for operators, chemists 5.4 Site Clearance Plan According to the regulations of the project Improving sustainable income and improving the quality of human resources for peaceful rural communities in Quang Binh province, the project only supports capital to build infrastructure, no funding for site clearance Therefore, the Commune People's Committee is responsible for site clearance and coordinates with relevant units to carry out site clearance for handover before the project starts Technical instructions for major works 6.1 Site preparation, receiving and cleaning Receive construction site The site management board will work with the Investor, Design Consultant, Supervision Consultant to carry out the delivery and receipt of the construction site The details are as follows: 23 Get landmarks Fixing and checking on design drawings, making Minutes of handing over piles, landmarks and reinforcements for each position, each item on the construction site Tools: Theodolite, hydro flask, nivo, total station, etc During construction, the measuring machine system is regularly used to check and locate the center and core of construction parts on the basis of landmark centre, standard elevation Locating the work before starting construction work The construction unit recognizes the landmarks and sets up the main center pile grid system for each specific item, arranges additional landmarks necessary for the construction All landmarks are led out of the influence of the construction machine, properly fixed and carefully protected so that the main landmarks can be quickly restored to the design position when inspection is required Determine the exact distance between work items, then send the above landmarks to safe locations that will not move during the construction process of the work While performing the work of locating the work, the construction unit ensures correct and accurate identification of locations such as the centre and axis of the work that the design consultant has handed over Fixed the basic axis, the horizontal and vertical axes of the construction in the field by the locating rack system and fixed by nailing and painted lines To locate the foundations, measure the centre position and elevation with steel piles using a construction machine After fixing with steel piles, use theodolite to check the accuracy of landmarks and determine by ink lines for each foundation, pile, column The center axis, column system is always checked by measuring machine, before installing reinforcement, coffa and after pouring concrete For raw water pipes and clean water transmission and distribution networks, the construction unit must accurately determine the centre line, the height of the back of the pipe according to the landmarks, the distance to the fixed standards 24 along the route such as electric poles , fence, other fixed points Pay special attention to locations with pipe rotation angle, positions with variable elevation, locations that cut through underground works, other architectural works Record arising points, deviations from the design and report to the Investor, Supervision consultant, Design consultant to find solutions before implementing construction Cleaning of construction site The construction unit conducts ground clearance work before starting official construction work Cleaning is carried out by mechanical combined manual - Clearance: All trees, obstacles, materials within the scope of the handover will be cleaned up In case there are materials belonging to the people or the State within the premises, the relocation must be agreed upon (for materials of large volume, moving far away, the Investor must be reported to the project owner) treatment direction) As for the raw water pipeline as well as the supply water pipe, the site cleaning will have to be carried out in parallel during the construction process - Peeling: The topsoil should be removed and moved to another place before excavation or backfilling, with the thickness of the excavated soil indicated on the design drawings - Disposal of materials: The materials are incinerated or moved out of the construction site to the gathering place as approved by the Investor Power supply, water supply, communication for construction: - Electricity: After starting the unit, contact the local power company to install temporary Electricity meters used during construction In addition, there is always a generator on the construction site in case of interruption of power supply due to breakdown or periodic interruption of power supply Power supply capacity as well as generator capacity ensure sufficient supply for all construction equipment on site 25 - Water: the construction unit uses the existing water source to serve the construction In addition, backup wells can be drilled to ensure sufficient water for construction with the highest quality - Communication system: Contact the phone company to supply and install landline telephones, with ADSL modems to ensure communication and update for the Site Management Board Key staff in the construction site are equipped with mobile phones A set of short-range radios is available to serve the needs between construction departments - The traffic and drainage system uses temporary roads and self-destructing sewage pits 6.2 Technical solutions for pipeline network installations Construction surveying work Receiving the handover of the basic landmarks from the Investor, these points will be the basis for the implementation of the next survey works and the long-term acceptance The design and actual status of the work, the grid of these landmarks will be carefully preserved during the construction process and later used to monitor the work Control points, including Construction site control net: the construction site control grid points have a milestone made of cast-in-place concrete with a size of 20cm, a depth of 30-35m, with a steel or porcelain base with a sharp cross engraved In buildings, it is possible to use additional landmarks that are shot directly at fixed objects Construction high-mode control grid: the high-control points (which are the standard points) have a spherical head structure arranged in stable places Special attention is paid to the landmarks buried deep to the stable soil layer, the high-level control grid is connected to the national altitude and the elevation is led directly from the high-level control points to build the construction control network Ground displacement, elevation and axis displacement 26 Position the site by building around the perimeter of the site Use those points to navigate upward with an accurate theodolite Measure the length with a steel ruler with an average error of 1/5000 from which to mark the axis center positions When marking, turn on the ink on the floor, these lines are used to check the formwork of the masonry wall Change the height with a water level machine and a steel ruler After the height control system is in place, the next job is to put it in the field by means of a water tank, these landmarks are measured to turn ink into the wall for later use such as installing paving doors 6.3 Construction of transmission and distribution pipe network Prepare locations to gather pipes and other materials for construction The transportation of pipes from the warehouse to the construction site is carried out by special vehicles with horns and warning lights to ensure traffic safety Make a construction plan for each line In which, it is necessary to solve the problem of local circulation to avoid the construction area: to arrange signs, fences, boundaries that must not be violated, lighting of the construction area, bypass of the construction area For locations where the road must be cut for construction: A bypass must be arranged for people and vehicles to pass through Barriers must be sturdy, with signs from a distance and traffic coordinators With locations, roads without bypass (dead-end road), only ½ of the road can be constructed After completion, construction of the remaining ½ of the road will continue Before the construction of the route, it must be informed to the local authority and people to avoid traffic into the construction area Market areas, agencies, schools, medical stations must carry out night construction so as not to affect the operation of these agencies After construction, the site must be returned immediately, and the temporary site return must be completed before am 27 Excess excavated soil must be immediately moved out of the construction area, without affecting the circulation of people Sand blocks, soil blocks for leveling must be left inside the roadside The road surface must be cleaned immediately after construction is completed 6.4 Installation of pipes and fittings General rule: Pipe installation work is carried out after the pipe foundation has been accepted and accepted as satisfactory Before laying down the pipe, the pipe must be checked and accepted, the contents include: (1) Check the appearance of the product in turn according to the standards of the product, if it does not conform to the requirements of the standard, it must be re-marked and treated separately; (2) Sections that have been specified to be tested for tube deformation are required to first measure the actual diameter, and then record it It is possible for workers or machines to lay pipes For excavated ditches with slopes, it is also possible to use a flexible cable to fasten the two ends of the pipe to ensure that the body of the pipe slides evenly and evenly into the trench, it is strictly forbidden to let the pipe roll from the top of the ditch into the excavated ditch; When using machinery to put pipes into the ditch, a flexible cable must be used for hoisting, it is strictly forbidden to thread the rope through the pipe for hoisting When adjusting the length of the pipe, it is possible to use an electric saw or a hand saw to cut, the section must be flat and vertical, without chipping Connect the pipes by the opposite connection method Before connecting, crane the pipes into position, install the telescopic pipe in the position of the need to connect, wait for the leak prevention work to be completed, then tighten the bolts In order to avoid the situation of deflecting the arranged pipe's shaft position during pipe connection, it is necessary to use a method of stabilizing the pipe 28 Specifically, it is possible to fill the bag with golden sand, sew the mouth of the bag and then put it on top of the arranged pipe The number of sandbags depends on the pipe diameter After connecting the pipe, it is necessary to check the pipe level and the shaft line to ensure that the pipe connection meets the requirements Construction in the rainy season must apply measures to prevent pipes from floating, peeling off and axis deviation After installing the pipe, it is possible to fill the ground in advance to a stable height against the buoyancy of the pipe Pipelines must be installed in turn according to construction design requirements and construction conditions The wall of the valve pit placed on the pipe must be plastered and cemented, the bottom of the valve pit must be treated with waterproofing, the wall of the valve pit and the pipe joints must be meticulously treated for waterproofing 6.5 Sand, backfill and resurfacing work After installing the complete pipe and fittings to return the surface to the excavation work, follow these steps: Fill the back of the pipe with sand layer by layer, watering to compact The sanding to protect the pipe must be carried out in layers, each layer is 30mm thick Compress evenly and carefully, then pour the next layer of sand until the design height is reached While compacting can be watered with appropriate dosage to ensure the correct "k" compaction coefficient specified by design Sand filling is carried out sequentially in layers until the design elevation is set, when compacting, depending on the location, a rammer or a table compactor can be used At locations where spare parts are installed or valve pits are arranged, formwork and supporting bulkheads are carried out, no backfilling is carried out For these locations, filling and resurfacing work is done only when the concreting work of the pedestal is completed or the bulkhead construction of the valve pit is completed 29 After completing the backfilling of the pipe, backfilling shall be carried out, following the same order and requirements as sand filling At locations where pipes pass through existing works (floors, yards, roads, etc.), they must be temporarily rebuilt with compacted crushed stone to ensure traffic and wait for subsidence After the settlement compensation period, reestablish the ground according to the current state before construction 6.6 Construction of the roadway pipe: Drilling and digging activities at the construction site must ensure the safety of the work and employees at the construction site, as well as ensure traffic safety Take all necessary measures to collect and drain water from ditches and excavations (slanting surface, drainage ditch, sump, pump, etc.) to avoid adverse effects on existing roadbed soil and prevent landslides road surface landslide Road excavation work will ensure traffic safety for vehicles and passersby, such as making sure overpasses for people and vehicles to cross, not to cause traffic jams caused by road excavation Coordinate with local authorities to arrange routes to avoid the excavation area The two ends of the road will be blocked to ensure safety, and there will be directions to avoid routes, and there will be a guard to guide the traffic For drilling, digging and cutting positions at road junctions and crossroads: Only one side can be made, the remaining part of the road is at least 2.5m so that people and rudimentary vehicles can circulate Large and heavy vehicles will have to follow the bypass route The construction site will be fenced with a steel frame covering corrugated iron to ensure safety Install signs at both ends of the work with full content in accordance with the regulations of the Road Administration of Vietnam, the Department of Transport and Public Works Excavation, pipe fitting, sand filling, soil and rock filling will be carried out quickly After finishing the layer of crushed stone lining the new ditch, it will be transferred to the construction of the remaining side road 30 After the construction is completed, the road surface will be returned immediately 6.7 Pressure test Preparation and tools of pressure test - Install solid flanges in all branches, air release valves, exhaust valves, etc., place bearings and pipe anchors according to the design Apply soil to the back of the pipe and support before testing - At the beginning and the end of the pipe to be tested, install 02 tested pressure gauges of type ÷ 12 kG/cm2 - Place the air release valve on the solid flange at the end of the pipe and the highest positions on the test route, to ensure that all air is released before the pressure test Check the backrests and supports for enough pressure when testing - Prepare sufficient means to pump water into the pipe and other means when it is necessary to repair the pipeline - Only clean water should be used for pressure testing Length of pipe must be tested for pressure - Normally, when the pipe section is installed 500 ÷ 1000m, the pressure test must be carried out Depending on the specific construction conditions applied Pressure test stages - Backfill the pipe with sand, fill 1-2 layers of soil before pressure testing After the pressure test, the canal will be completely filled and re-leveled - Pump water into the pipe - Fill the pipe with water at the lowest point, and at the same time, there must be an air release device installed at the highest point of the pressure test pipe - The pipe must be filled with water at a pressure of 0.5 kG/cm and held for about 24 hours before the pressure test - Any leak detected while filling the pipe and waiting for it to soak must be repaired immediately - Pressure test in two stages: Stage 1: 31 - Test the durability of pipes with test pressure according to the design of each route - Increase the pressure in the pipe to the design pressure by continuously pumping water into the pipe, keeping this pressure value for 02 hours (permissible pressure fluctuation ±0.5 kG/cm2) If after 02 hours, the pipe joints are not broken, the endurance test period can be ended Stage 2: - Test the tightness of the pipe with the test pressure according to the design requirements of each section - Raise the pressure of the pipe to the design requirements of each section and maintain this pressure for not less than 02 hours - The test pipe will be approved if the pumped water flow does not exceed the allowable leakage value according to AWWA C600 – 93 standard: + L: allowable water loss (leakage) (l/hour) + S: Length of pipe to be tested (m) + D: Nominal diameter of the pipe to be tested (mm) + P: Pressure to be tested kG/cm2 - If after 10 minutes the pump inflow is q > the allowed additional water flow, the watertightness of the installed pipe is not satisfactory Detection should be considered to rule out leaks or undischarged gas reservoirs When you are sure that the repair is complete, proceed to retry until the specified requirements are met - In case of pressure drop, it is necessary to check along the test route, find out the damaged leak and fix it immediately After the repair, the pressure must be re-tested - The pressure test work of each stage is considered completed only when the Investor and the Supervision Consultant approve the acceptance 6.8 Disinfection and washing: After the pipeline has been pressure tested, the connection is completed and approved, it must be disinfected before being put into use 32 Disinfectant dispensers must be filled with clean water while the disinfectant solution is filled through a convenient junction with a volume such that the final solution contains 60 mg/liter of residual chlorine - The pipeline is accepted clean after meeting the following two requirements: - Take a water sample at the end of the tube with disinfectant solution after 24 hours of testing for residual chlorine - After sterilization, drain the water in the pipe through the fire hydrants, connectors, with the required flow rate in the pipe V = 0.75m/s A sample of the water at the end of the tube after rinsing the disinfectant solution is found to be of the same quality as the water of the existing system 33 ... Calculation of tank capacity: The capacity of the clean water tank is determined according to the working mode of the raw water pipeline of the level pump Raw water pipe works of raw water pipes 24/24... hydraulic calculation of water supply network Hydraulic calculation of the entire water supply network in order to select the pipe diameter to ensure: - The pipeline network has enough capacity. .. construction site in case of interruption of power supply due to breakdown or periodic interruption of power supply Power supply capacity as well as generator capacity ensure sufficient supply for all construction