By Joyce Peterson,2014-12-25 23:41
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Construction Method Statement of

    Water Supply, Drainage and Firefighting Engineering

    in Dry Port

? General

    The water supply engineering of this project contains 1946m installation of PE?DN50~DN300?water supply pipeline and 12 valve pits. The water drainage engineering is constituted by 2256m installation of HDPE ?DN50~DN300?plastic pipeline, 50 cast-in-site reinforced concrete square manholes, 8 brick round manholes, 84 gutter with single grating, and the installation of oil wastewater treatment plant. The firefighting engineering mainly contains 10 outdoor below-ground and above-ground hydrants and 9 outdoor reinforced concrete below-ground hydrant pits.

    ? Construction Staff, Machinery and Equipments, and Schedule


    2.1 List for Construction Staff

    Table 1: Construction Staff

    No. Type of Job Post Quantity 1 Project Manager 1 2 Deputy Project Manager 1 3 Project Deputy Chief Engineer 1 4 Engineer 2 5 Technician 1 6 QA/QC Engineer 1 Management 7 HSE Engineer 1 8 Test Engineer 1 9 Machine Engineer 1 10 Business Engineer 1 11 Survey Engineer 1 12 Material Engineer 1 13 Machine Driver 8 14 Machine Repairman 2

    Operation 15 Foreman 2 16 Technical Worker 30 17 Local Worker 30 2.2 List for Construction Machinery and Equipments

    Table 2: Construction Machinery and Equipments No. Name Model Unit Quantity 1 Crane 40T/55T 1 2 Excavator PC200 1 3 Concrete mixing plant 120m3/h Set 1 4 Concrete delivery truck HDJ5241JBFU 2 5 Generator 4BTA3.9-G2 50KW 1 6 Water truck SLA5200GPSE 1 7 Oil truck SLA5152GJYE 1 8 Total station instrument TC802 1 9 Gradienter NA2 1 10 Electric melt machine 2

    Electromotion booster 11 1 pump


2.3 Construction Schedule

    thThe construction shall be started on July 15 2009, and completed on

    thDecember 27 2009.

? Construction Method

    3.1 Construction Technology Process

    The construction technology process of water supply and firefighting

     foundation trench engineering shall be as follows: setting-out survey?

    excavation? foundation tamping? pipelines installation? pipeline joints

    treatment? well chamber construction? pipeline pressure test? firefighting

    equipments installation? foundation trench backfilling and tamping.

    The construction technology process of water drainage engineering shall contain: setting-out survey? foundation trench excavation? foundation

    tamping? pipelines installation? pipeline joints treatment? well chamber

    construction? sealing test? foundation trench backfilling and tamping

    3.2 Construction Method

    3.2.1 Setting-out Survey

    According to design drawings, pipelines shall be set-out and surveyed, mainly for marking the positions and elevations of the trenches in site. 3.2.2 Foundation Trench Excavation

    The foundation trench shall be excavated mainly by excavator, finished manually. The excavation by machine shall be till 0.1m above the bottom of foundation trench according to pipe diameter and design requirements, continued to be cleared manually to designed elevation, with no disturbance to parent soil.

    For water drainage engineering, if the excavation depth is beyond 2m, channel beams shall be used for temporarily vertical supports on both sides, which shall also be supported by profiled steels at certain intervals to keep the


    stability of both slopes. The temporary supports need to be approved by Employer’s Representative before use.

    3.2.3 Foundation Tamping

    With the completion of foundation excavation, the surface of foundation bottom shall be tamped by tamping machine before paving medium-coarse sand foundation of 10cm thickness, also tamped by tamping machine and watered.

    Table 3: Test of Foundation

    Test No. Test item Test standard Test frequency method

    Compaction Sand Comply with One point for every 50m 1 degree replacement design requirement of foundation trench

    3.2.4 Pipeline Installation

    The center line shall be set out before installing pipelines manually assisted by truck crane. The pipes shall be colligated by soft ropes and put in the trench slowly with supports and sprags fixing temporarily. Each pipeline shall be installed on the paved sand bedding course tightly and combined well for uniform bearing.

    Table 4: Allowable Deviation of Pipeline Installation

    Allowable deviation?mm?


    Water drainage pipe Water supply pipe

    Position of axes 15 30

    Elevation of pipe inner bottom ?15 ?30

    3.2.5 Pipeline Joints Treatment

    The pipeline shall be jointed by electric melt sleeve in accordance with design requirements. The voltage and heating of electric melt shall comply with the provisions of electric melt joint machine and welding technics parameters. They will be recorded. While welding, the current status shall be watched. During cooling time, the connection fittings can’t be removed or forced The

    cooling method shall adopt natural cooling, not appropriate to be forced cooling,


3.2.6 Pipeline Wash and Disinfection

    With the completion of water supply pipeline installation, the inner part of pipeline shall be cleaned before hydraulic test. For the portable water pipes, they shall be disinfected by dissociating chlorine before use according to design requirements.

    After pressure test, the pipe shall be disinfected by keep full water with dissociating chlorine of 20?30mg/l for over 24 hours.

    3.2.7 Well Chamber Construction

    The well chamber construction shall be carried out subsequently after pipeline installation, including round valve pit φ1200mm, outdoor reinforced

    concrete below-ground hydrant pit Φ1200mm, and square manhole 1100×

    1100mm, strictly following design requirements and related standards.

    For installing the well ring, the center line shall be set out by surveyors first, and the top elevation must be controlled by level instrument, The cast iron well bottom between well ring and well chamber shall be filled with M10 cement mortar of 10mm.

    a. Concrete Bedding Course Casting?C10?

    With check out of foundation tamping, the position and elevation of concrete bedding course sidelines shall be set out before concrete casting. The C10 concrete shall be delivered to foundation bottom by crane raising cage, spread manually, vibrated and compacted by flat slab.

    b. Reinforced Bar Colligation and Installation of Embedded Units and Formworks

    The reinforced bar colligation shall be carried out after lean concrete bedding course construction. According to design drawings, the framework of reinforced bars shall be checked and accepted entirely.

    Both inner and outer side formworks shall adopt light-duty steel structure, installed and removed by crane with manual assistance.

    c. Concrete Casting and Curing

    The concrete shall be transported to site by concrete trucks, casted


    assisted by raising cage of crane, spread in formwork manually with a height of free fall less than 3.0m, vibrated and compacted with individual thickness of 30?50cm,

    The formwork can only be removed after the concrete reaches certain strength, immediately curing by fresh water.

    Table 5: Allowable Deviation of Well Chamber

    Item Allowable deviation?mm?

    Length, width ?20

    Dimension of well body

    Diameter ?20

    Elevation between well cover and road ?5

    D?1000 ?10

    Elevation of well bottom

    D?1000 ?15

    3.2.8 Pipeline Pressure Test

    The pressure test of pipelines shall be carried out strictly according to design requirements, with the covering backfill soil on both sides and top no less than 0.5m.

    The technical requirements of pressure test: When the pressure of pipeline rises to test pressure 1.0Mpa, keep the constant pressure for 10 minutes. If theres no failure and leakage of joints and pipes, the strength of pipeline can be eligible. If the pressure falls no more than 0.02Mpa, the sealing can be tested to be eligible.

    Hydraulic test is adopted for pressure test, carried out after check out of appearance. To guarantee the construction of subsequent procedure, the pressure shall be tested in sections of every 100m with reference to site situation and construction schedule. The pressure test for integral pipeline shall be carried out with the completion of all water supply pipe installation.

    The leak test shall be start after the installation and check-out of water drainage pipelines. The test pipes are severed according to well space but with the scale of wells. When the test pressure reaches required pressure, timing


    and observation shall start. Water shall be filled in test pipeline continuously till the end of observation. The test pressure shall be kept constantly, and the observation of water leakage shall last no less than 30 minutes, and the allowable leakage shall comply with requirement of specification. 3.2.9 Firefighting Equipment Installation

    For the firefighting equipments, outdoor hydrant SS100/65-1.0 and SA100/65-1.0 are adopted for the project.

    oConcrete support shall be set at the base of firefighting 90 elbow. The

    well cover shall be marked by Hydrant and paint in red.

    3.2.10 Foundation Trench Backfilling

    The top of the pipelines shall be backfilled by excavated soil, tamped by tamping machine in layers with each of 30cm thickness. There shall be no stones with diameter more than 20mm contained in the backfill soil 50mm on the top of pipes. The compaction degree shall meet design requirement before the backfill of next layer. Furthermore, the joints position of pipes shall be backfilled after completion of pressure test.

    Table 6: Minimum Compaction Requirement for Soil Backfilling

    Depth from sub-base?cm? Minimum compaction degree?%?

    ?80 95

    ?80~150 93

    ?150 87

? Quality Insurance Measures

    1. The pipe materials shall be stacked on a clean and smooth yard, avoiding bending. If theres some damaged materials, they will be removed from the stack.

    2. While excavating trench, the elevation of foundation bottom shall be strictly controlled, with no disturbance to parent soil.

    3. If theres ground water, it has to be drained until backfilling.


    4. The pipe materials shall be carried and installed slowly and gently. During pipe installation, there shall be no water in trench.

    5. The pipe materials shall be cut by machine, with cutting plane smooth and vertical with pipeline axes.

    6. While pipeline jointing, the spigot, sleeve and sealing elements etc. at joints shall be cleared without soil, water and other impurity.

    7. The axes at joints shall be aligned on the same axes of pipeline before electrifying. Moreover, the conducting wire shall be checked. The voltage and time of heating shall comply with the welding parameter provisions of electric melt pipe fittings.

    8. In the process of melting and cooling, the joints and pipeline on both sides cant be moved and turned, and no force can be put on them.

    9. The trenches must be backfilled immediately after the installation of pipelines. Before the pressure test of water supply pipelines, they are appropriate to be backfilled less than 0.5m except the joint positions.

?. Control Plans for Safety Construction

    The dangerous sources during construction are as follows: the traffic danger during travelling of machinery, dangers of power supply and collapse of foundation trenches.

    According to the dangerous sources, the following control measures of safety construction can be adopted:

    1. Enough safety caution marks shall be set up in site.

    2. Safety technical explanation shall be made to the workers before taking post.

    3. Safety officers shall be arranged to supervise the operation of the workers. 4. Before the concrete delivery trucks transport concrete, the performances of the trucks shall be checked by the drivers. During the transportation, the drivers shall not only pay special attention to the passerby and other vehicles,


    but also drive slowly according to the fixed route to avoid traffic dangers. 5. The construction power supply and machinery shall be executed in accordance with the requirements of specification.

    6. Workers shall be organized to drill of meeting an emergency, which can increase the safety consciousness of workers.

    7. The deposit soil by machine from foundation trench excavation shall be at least 2m far from the trench, while that by manually excavation shall be at least beyond 0.8m, and the height must be controlled within 1.5m. When the excavation depth is over 2m, channel beams shall be adopted for temporary support to prevent collapse. Furthermore, safety ladders, not made by bamboo, will be used for getting up and down the trench.

    ? Control Plans for Occupational Health, Environmental Protection and Civilized Construction

    Certain personals with necessary personal protection equipments shall be arranged to clean and water the roads dump trucks travel on. Rest shed shall be provided for the workers to prevent calenture. Furthermore, generators with low noise shall be used, and special zones for machinery cleaning, maintenance and repair shall be set up.

? Cleaning, Maintenance and Repair of Machinery

    Special workshops for machinery cleaning and maintenance have been set up on Dry Port camp, in which the machinery cleaning site is special for machinery cleaning, where the water after cleaning can be used after 2-grade settlement to avoid water waste and water pollution, while the maintenance and repair workshop is special for machinery maintenance and repair, charged by professional maintenance engineers and workers.



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