This Method Statement of Storm Drainage (Installation and Testing) defines the requirements for installation and testing of vitrified clay pipes and fittings for the storm drainage system. Moreover, this provides guidelines to check that specified materials are installed and as per quality procedures, health, safety & environmental (HSE) standards are implemented during the execution of work.
The specifications, procedures, and guidelines contained in this method statement specify the technical requirements to be followed and also act as a reference to clearly establish standards for work assessment.
Transportation, Handling, and Storage
- All materials shall be handled/transported/stored in an optimal way that will not cause
damage to them.
- The material will be delivered at the site in undamaged condition, in manufacturer’s packaging,
with identifying labels intact and legible.
- Pipes are to be checked on unloading. Possible damages are reported on the delivery note.
- Timbers and packing shall be provided by the contractor, necessary for the correct stacking of
pipes, fittings, and other delivered materials.
- Pipes or fittings will not be drop or drag.
- Pipes and fittings will be offloaded in our laydown area prior to transport to the site.
- The storage area must be flat. The ground must not be marshy or unstable.
- Timber supports of suitable size shall be placed at an equal distance below the vitrified clay
- Pallets are loaded/unloaded only by convenient equipment (i.e. a forklift) which do not
allow any damages to pipes and fittings.
- Dropping, lifting, or lowering pipes with jerking movements or suddenly letting them to the
ground will cause damages. In case of other lifting machines (i.e. Cranes) is used for loading/unloading, wooden bars must be laid between the slings to ensure that no damages occur to the pipes
- Pipes shall be handled special care during transportation/loading in order to protect from accidental damage. Use hooks with special protection of plastic or rubber to avoid damage to the exterior of the pipe.
- The layer of pipe stacks will be in accordance with the manufacturer’s storage and handling recommendations.
- Do not move the pallets on the truck with the aid of levers or crowbars.
- Put the pallets down only on the ground that is sufficiently hard to prevent the base timber from sinking into it.
- Leave sufficient space between individual pallets.
- The storage area shall be cleaned and is at an appropriate height from the ground level. The materials shall be stored in a shaded area to protect them from exposure to direct sunlight/rain etc. Separate areas in the storage zone must be marked for different materials.
- Whenever heavy or bulky material is to be moved, the material handling needs will be evaluated in terms of weight, size, distance, and path of movement.
- Never transport individual pipes in the excavator shovel.
- Dragging or rolling pipes is not allowed. Packs or individual pipes should be set down on a reasonable leveled surface and off the ground by a square timber to protect the “K” joint of the spigot end from the damage.
- Pipes shall be stacked on a flat surface free from any sharp objects and shall be given adequate supports at all times. Put down the parcel on flat ground so that the pipes do not slip when the securing bands are cut.
- Damaged and defective pipes shall not be used at the site. The pipe shall be re-inspected just prior to installation. Pipe shipping, storage, and handling shall comply with the manufacturer method statement.
For materials to be inspected (as per approved material submittal after receiving at the site, the following points are to be followed:
- Each material item shall be allotted a distinct and separate reference number and mentioned on the material requisition. Make sure that material is approved/examined by the Consultant and QAQC and associated documents/test certificates are approved.
- The Store In-charge shall ensure that all approved supplies be delivered to the site as per the approved material submittal; with the manufacturer’s seals, labels, or other proof of origin intact. These labels and seals shall not be removed until the material is required for use and shall be retained for inspection by the Consultant and QA/QC.
- Store In-charge shall initiate material inspection for all incoming material to QA/QC and the material shall be inspected against reference documents and as per approved material submittal. Moreover, the physical condition of the material shall be checked. Afterward, an IR (Inspection Request) shall be raised by QA/QC to the Consultant and inspection will be carried out by the Consultant.
- Materials, which do not conform to the given specification/approved material submittal, shall be rejected. Any discrepancies or damages will be notified and reported for further action.
- For any materials inspection (especially pipes, fittings, other accessories), the items shall be segregated as per their type/sizes and placed items separately in racks or on different pallets.
- Each rack/pallet shall have an identification posted on laminated paper with the description of the items clearly written on it.
- There shall be appropriate spaces between the pallets so that the engineer/inspector can freely go around them and inspect the materials thoroughly.
- Staking the materials all over each other & in one corner is strictly not allowed.
- All items shall be kept in a protective environment and shall not be kept directly on the floor; they shall have wooden pallets underneath them.
- All necessary work permits shall be obtained prior to the commencement of any activity at the site and shall remain valid throughout the entire duration of the operation.
- Site interface permits to be taken from other contractors before placing pipe at tie-in point to reconfirm invert level and coordinates.
- All activities for surveying, earthwork, trench excavation, pipe bedding in trenches, initial backfilling and final backfilling, laying of marker tapes, and all associated jobs relate to Civil shall be done by Civil Contractor.
- Dewatering shall be added if the excavation level is lower than the water table. Dewatering shall be performed by Civil Contractor.
- Check & verify that the civil work is completed in compliance with all requirements for installation as per approved shop drawing and handed over for mechanical works. Joint inspection of the location shall be carried out by Consultant & Contractor before releasing the excavated trench for installation works.
- For water-logged area, Gabbro material as gravel shall be used.
- Prior to the commencement of work, inspect areas and access to confirm that the site is ready to commence the work and coordinate with other trades and subcontractors.
- Ensure that proper and dry trench beddings are placed.
- Ensure that gridlines, reference levels, etc. are marked.
- Ensure trenches are free from obstruction, rocks, and other debris prior to laying pipes.
- All relevant documentation approved shop drawings, and material applicable to a particular section of works will be checked by Site Engineer prior to commencement of work.
- Ensure that Material received is in compliance with the Project Specifications/Authorities Regulations and is approved.
- Ensure that all required materials and accessories are delivered, inspected, and approved by the Consultant and are readily available at the site to carry out the work.
- The site Engineer and his Supervisor/Foremen will carry out a site survey and mark the route of piping as per approved shop drawings. In the event of any discrepancies or difficulties in executing the work, these shall be brought to the notice by the Construction Manager for corrective action.
- All relevant documentation (includes MST and RA are approved, obtain necessary work permits, fill up STARRT cards after completion of daily toolbox talk), will be checked by Site Engineer prior to commencement of work.
- The Site Engineer/Site Supervisor will give necessary instructions to tradesmen (Plumbers/pipe installers) and provide necessary approved construction/shop drawings.
- The Site Engineer/Site Foreman will check that proper tools and equipment are available to carry out the work and are in compliance with contract specifications.
- The Site Engineer will explain to his team about HSE precautions to be observed.
- Visually check the condition of pipe i.e. Crack, straightness, and rust.
- If the required length is not standard, pipe cutting shall be performed. Preferably cutting of pipe should be avoided at the site.
- Pipes up to 450 mm in diameter shall be cut by chain cutter. Pipes 150 mm and 100 mm in diameter shall be cut by using a cutting ring.
- Measure the required pipe length and mark it for the cut.
- Adjust the chain at the required length of the pipe for cutting.
- Tight the chain around the pipe and buckle it up with the arm of the cutter and fold back the surplus chain.
- Tighten up the chain by turning the horizontal handle till the pipe is cut.
Laying of pipes in Trench Bedding
All Civil related works are mentioned here for reference only. Civil works shall be performed by Civil Contractor.
The laying of drainage pipes in trenches shall be in accordance with the relevant provisions of project specification/manufacturer’s recommendations.
- Vitrified clay pipes shall be installed in trenches that shall not exceed the maximum trench width at 300 mm above the crown of the pipe as shown in Table 2.1.
- Pipe bedding shall be provided as shown on the Drawings or stated in the Contractor’s approved methods statement.
- Pipe bedding shall be well compacted and shall completely fill the whole width of the trench excavated.
|Nominal Bore mm||Maximum Trench|
|Nominal Bore||Maximum Trench|
Granular bedding material for rigid pipes shall conform with the following requirements:
- Shall be clean gravel or broken stone from a source approved by the Engineer.
Gabbro shall be used in water-logged ground.
- The granular material size shall be according to the following grading limits giving in Table 2.2.
|Nominal Bore mm||BS Sieve Size, 100% Passing By Weight-Dry Condition||BS Sieve Size, 100% Passing By Weight-Wet Condition|
|100 & 150||14||20|
|1000 & above||37.5||50|
- Bedding for pipes shall be constructed by spreading and compacting granular bedding material over the whole width of the pipe trench.
- Bedding material shall be in accordance with the project specifications.
- Nominal single-sized aggregate and graded aggregate shall comply with Table No. 4 of BS 882.
- Sand for bedding material shall comply with the relevant provisions of BS 882.
- Bedding systems other than those specified in this clause may be allowed upon approval of the Engineer or as recommended by the pipe manufacturer.
- Unless otherwise specified, pipe bedding shall be as shown on the Contract Drawings.
- Notwithstanding the above, for vitrified clay pipe, the special pipe bedding requirements as Table 4.2 are to be provided in all cases whether or not shown on the drawings or indicated in the bills of quantity.
|Nominal bore mm||Depth to Invert (D) m||Bedding Type|
|700-800||D>9.0||220.127.116.11.1 Plain concrete|
|>900||4.0<D<5.0||18.104.22.168.2 Plain concrete cradle|
|>900||5.0<D<9.0||Reinforce concrete cradle with|
minimum 0.4% transverse steel
|>900||D>9.0||Reinforced concrete surround with|
minimum of 1% transverse steel
- Where socketed pipes are required to be laid on a granular or sand bed, or directly on a trench bottom, joint holes shall be formed in the bedding material or final excavated surface to ensure that each pipe is uniformly supported throughout the length of its barrel and to enable the joint to make.
- Pipes shall be laid on setting blocks only where a concrete bed or cradle is used and is required by approved drawings and project specifications.
- Where pipes are required to be bedded directly on the trench bottom, the final excavated surface shall be trimmed and leveled to provide even bedding for the pipeline and shall be free from all extraneous matter that may damage the pipe, pipe coating, or sleeving.
- Where rock is encountered, the trench shall be cut at least 150 mm deeper than other ground and made up with well compacted selected fill material.
- No protective cap, disc, or other appliance on the end of a pipe or fitting shall be removed permanently until the pipe or fitting which it protects is about to be jointed. Pipes and fittings, including any lining or sheathing, shall be examined for damage and the joint surfaces and components shall be cleaned immediately before laying.
- Suitable measures shall be taken to prevent soil or other material from entering pipes and to anchor each pipe to prevent flotation or other movements before the Works are complete.
- Where pipeline marker tape is specified in approved drawings/specification, it shall be laid between 100 mm and 300 mm above the pipe.
- Marker tape shall be installed as per the project specifications. Its wording and color shall be in accordance with the project requirement. For Foul water Red color tape.
- Coatings, sheathings or wrappings shall be examined for damage, repaired where necessary, and made continuous before trench excavations are backfilled.
Backfilling shall, wherever practicable, be undertaken immediately the specified operations preceding it have been completed. Backfilling shall not, however, be commenced until the parts of the works to be covered have achieved a strength sufficient to withstand all loading imposed thereon.
- Suitable material shall be used for backfilling. All required tests shall be performed prior to bedding surround / backfilling.
- Backfilling around existing structures shall be undertaken in such a manner as to avoid uneven loading or damage.
- Filling material to excavations shall be deposited in layers not exceeding 250 mm unconsolidated thickness and compacted to 95% modified proctor.
- Where the excavations have been supported and the supports are to be removed, these, where practicable, shall be withdrawn progressively as backfilling proceeds in such a manner as to minimize the danger of collapse. All voids formed behind the supports shall be carefully filled and compacted.
- All safety measures shall be taken during excavation, bedding, compaction, and backfilling.
- The open trench will be barricaded by warning tape. A warning sign shall be in place i.e. “Danger” “Deep Excavation” “Keep Away” “Do Not Enter” “Work Under Progress” etc. Trench barricade requirement shall not be limited to warning tape, adequate barricade to be provided to suit site conditions and area.
- After completion of backfilling the pipe trench all warning signage, warning tape shall be removed and the area will be cleaned.
- Geotextile filter membrane shall be placed in the trench after formation level.
- Concrete surround shall be provided around the pipe if the minimum cover depth is less than 1.2 m.
Installation Procedure for Underground Piping
The laying/lowering of pipes shall be performed according to the project specifications, manufacturer’s recommendations, and project specifications.
- The trench will be made clear from any debris or any sharp object before laying the pipe in. The trench bottom will be level to provide uniform bearing and support of pipes.
- A trench survey will be done for ensuring the required pipe elevation as per approved drawings.
- Lower the pipes and fittings into the trench with a crane or any suitable lifting / lowering machinery or manually depending upon the weight, size, and length of the pipe. As per approved material and specification, any external treatment or protection (sleeves, etc) are not applicable.
- Wire rope or any metallic lifting sling will not be directly in contact with Vitrified Clay pipe while lifting or lowering into the trench. Cotton Jute or soft rubber material will be wrapped to avoid damage to the pipe at the place where the sling will tie for lifting the pipe. Care shall be taken to avoid damage of pipes during lowering into the trench. Care should be taken in lowering the pipe into the trench to prevent damaging the joint material or disturbing trench condition. Never allow the pipe to be damaged along the ground or even at the trench bottom.
- The pipe shall be laid in the upstream direction with the bell end laid upstream.
- Make/dig the pit (hole) in the soil under each pipe socket (Bell) for firmly resting pipe barrel on the trench bottom or bedding material so that load is supported by the pipe barrel and not the pipe socket.
- Join the pipe and fitting ensuring it invert elevation is as per the latest approved shop drawings. Please refer section jointing procedure of this method statement.
- For jointing methods, the manufacturer’s recommendation shall be followed where applicable.
- Pipe passing through the concrete/wall shall be installed in sleeve. Sleeve material will be as per approved material submittals. Pipe sleeve diameter to be 13 mm larger than the outside diameter of the pipe.
- If required to prevent misalignment, underground piping shall be stabilized and secured as per approved drawings or by thrust block at intervals, every branch, and every change of direction as specified in the specification or drawings.
- Protective caps shall be removed from pipes and fittings end prior to making joints and at every end of the working day, pipes ends will be covered or will close with end caps.
- After installation check for correct leveling, position, alignment, straightness, and required slope as per International Plumbing Code.
- Installation inspection will be offered for the part or complete portion of the entire underground piping. Air Testing Inspection will be offered after approval of installation. Both inspections will be independent.
- Piping will be backfilled and compacted as per project specifications. The minimum top coverage shall be 300 mm. This shall be in accordance with finalized specification document.
- Clean the hub and spigot to be joined so they are free of all dirt, mud, sand, gravel, and other foreign materials.
- Remove sharp edges by filling or tapping with a ball-peen hammer.
- By using a paintbrush apply the approved lubricant on both surfaces to be joined i.e. inside the socket end and outside the spigot end. Lubricant to be stored as per manufacturer’s recommendations. Apply lubricant to molding inside and on the spigot end (of K joint). Apply lubricant to lip ring and spigot end (of L joint)
- While applying lubricant care shall be taken to avoid contact with eyes or skin. The manufacturer’s safety instruction shall be strictly followed.
- Yellow marks printed at the external side of the pipes should be kept always at the crown.
- Prepare trench bedding in the proper way and make sure it’s homogeneous, leveled, and dry.
- Line up the socket and spigot and shave the pipes together with steady pressure, (for small diameters this can be done by hand while for larger sizes, a crowbar may be used). Care should be taken not to damage the lip of the socket by using a wooden block. The special device may be used for big diameters.
- Laying pipes should be in the upstream direction with the bell end laid upstream.
- Holes must be dug at each socket (bell hole) to make sure that the pipe barrel is resting firmly on the trench bottom or bedding material so that load is supported by the pipe barrel and not the pipe socket.
- Align (hub and spigot) yellow marks with other pipe yellow mark, then push spigot fully home into the socket/hub with steady pressure.
- Make the joint of further pipes/fittings as procedure mentioned above.
Tips for laying sewer pipes
- Keep the trench width narrow, especially at the top of the pipe. A wide trench means more load on the pipeline. Spread bedding material in front of the last pipe laid. Smooth it out.
- Imported bedding should be at least 4 inches thick – thicker for the larger pipe. Make sure the bedding is packed down.
- Use a grade rod, laser, or grade machine to check the grade of bedding. This means less pipe handling when the pipe is laid.
- Dig bell or coupling holes before the pipe is laid. Just scoop out bedding with a shovel.
- Keep water out of the trench so bedding can be placed and graded accurately. Pipe joints can be made easier too.
- Pump out water or use well points sunk below the depth of the trench bottom.
- Follow manufacturer’s instructions for installation of flexible compression joints (where required).make sure joints are clean before installing them.
- If a bar is used to shove the pipe home, use a block of wood to cushion the bell. Make sure the pipe is laid straight and to grade.
- Tamp a layer of bedding material under the pipe haunches, not under the bell. This gives the pipe added support and keeps it in line.
- If too much bedding is thrown on top of the pipe, it would not get under the pipe even with tamping. Don’t let this happen.
- Make sure fittings, stubs and risers are well supported. Tamp the soil around and under haunches of the pipe and fittings.
- Use short stubs with flexible compression joints at manhole walls (if project specification/drawings require). They will take care of the manhole settlements.
- Hand covers the pipe with about 12 inches (30 cm) of backfill over the top of the pipe. This protects the pipe during final backfilling.
- Do not let the rocks or lumps get into the trench. They can damage the pipe and ruin the alignment.
- Place final backfill into the trench at an angle. This keeps the impact on the installed pipe to a minimum.
- Heavy compaction equipment should be used with caution. The pipe can be damaged if the impact is not carefully controlled.
Swabbing/Cleanliness of Pipelines
- Before testing, cleaning and swabbing of the pipeline shall be carried out.
- Pipelines and manholes shall at all times be kept free of all silt, mortar, debris, and other obstructions. When work is not in progress the open ends of the pipeline shall be securely plugged with an approved watertight plug or stopper firmly fixed to resist unauthorized removal.
- The inside of each fitting and pipe length shall be cleared immediately before jointing and shall swab all fittings and pipe lengths to remove all dirt, sand, or other matter that may clog the pipeline or contaminate the fluid to be transported in the pipeline.
- After jointing, the interior of the pipes shall be freed from any dirt, stones, or other matter that may have entered them. For this purpose, a rubber disc, brush, or other suitable implements that will not harm the internal lining of the pipe shall be pulled through the pipe after jointing.
- Testing a pipeline shall be carried out before any backfilling takes place and shall be repeated after backfilling is completed, and should be in accordance with the standard specifications of water and air testing of drain and sewers.
- Each pipeline 600 mm or less in diameter shall be tested by air test. If any pipe fails the air test, the Consultant /Engineer may order a water test to be carried out. Acceptance of the pipeline will then be based on the results of the water test. All pipelines up to and including 1200 mm shall be tested by air test in accordance with the requirements of BS EN 752.
- Each pipeline shall be tested before backfilling and also after backfilling before carrying out road reinstatement or laying new road surfacing. Where the pipeline is located under a new road alignment, the pipeline will be tested after the sub-base compaction incomplete.
- All pipelines shall be subjected to pass infiltration tests as specified herein. All pipes are to be clean and empty at the time of testing. Tests shall be performed in the presence of the consultant/Engineer.
Air Testing of a Pipeline:
- Prior to Air Testing, IR (Inspection Request) will be raised for approval of the installation of piping work.
- Air testing of drainage will be carried out prior to closing / backfilling the trench.
- Piping may be tested in sections or in total, depending on on-site requirements.
- Trained Personnel will conduct the test monitored by a responsible site engineer and safety department.
- Arrange for test plugs, 4″ (100 mm) U – tube manometer test kit with accessories.
- Always coordinate with safety and construction departments for safe and methodical conduct of testing works.
Testing Criteria and Methodology:
- Installation Check – Piping layout, location, and size of pipe.
- Air testing shall be in accordance with the project specifications.
- Test Pressure-100 mm manometer (U – Tube) pressure.
- Test duration-5 minutes.
- Test Monitoring- pressure (in U tube – Manometer) should not fall below 3 inches (75mm) water gauge in 5 minutes.
- Pressure measurement/checking will be done in the U – tube manometer.
- Ensure that the pipes and fittings are capable of withstanding air leak tests.
- Air testing can be applied to the system in its entirety or in sections. Once the above is checked and found acceptable, proceed with the test.
- Inspect pipeline for possible damage during or subsequent to laying.
- Thoroughly check all plugs and equipment. The average drain plug is quite often not airtight and rubber tubing used in connections must be in good condition and not perished.
- Ensure that the ends of the line are adequately strutted against movement with all plugs held firmly in position.
- Pump or blow in the air until a pressure of slightly in excess of 4 inches (100mm) water gauge is indicated on the manometer connected to the system. Pumping or blowing warms the air so a minute or two should be allowed for this to cool to the pipe temperature.
- If necessary, then reduce the pressure to 4 inches (100mm) water gauge. During a further period of 5 minutes, the air pressure should not fall below 3 inches (75mm) water gauge.
- The Testing team will conduct a soap test at the joints if an air leak is identified.
- If any leaks are detected then they are to be attended to prior to proceeding further.
- Repeat the procedure after attending to the leaks (if any).
- Once it is confirmed that there is no leak in the system and maintain pressure in the piping for 5 minutes.
- Inspection Request (IR) will be raised for the client/ consultant to witness the Air Test. The local authority does not require witness the test.
- After consultant inspection, the system will be vented until normal pressure is attained.
Procedures for Handling Air Test Failure
I) Before Backfill
a) Readjust the pipe pressure to the specified test pressure and examine for leakage by pouring a
solution of soft soap and water over the exposed joints if the test fails.
b) Repair leaks and repeat testing where leaks are found at joints.
c) Where leaks are not found at joints, move the plug, the one that is not used to exert air pressure,
along the pipeline to isolate lengths with leakage. Uncover pipe barrels in the isolated lengths where
leakage in pipe barrels is suspected. Replace leaking pipe lengths and repeat testing.
d) Conduct low-pressure water testing to verify that the air test was not erroneous where the test
length fails the air test but no source of leakage can be identified. Consultant’s consent is required
as per site conditions.
II) After Backfilling
a) Move the plug up from the other end along the sewer pipeline to isolate the lengths that fail the
b) Exhume the failed length of the pipeline and replace pipe lengths.
c) Repeat the air test.
d) Conduct water testing to check that the air test was not erroneous when failed lengths could not
be isolated using the air test. Consultant’s consent is required as per site conditions.
e) Use CCTV or a suitable recording medium, when required or available, to identify the leakage if the
failed section cannot be isolated by the air test or water test.
Water Testing of a Pipeline:
(Shall be done after consultant’s approval where Air Test failed)
Before testing, attention should be paid to the following points:
1. Inspect pipeline for possible damage during or subsequent to laying.
2. Plugs, should be thoroughly checked. Faulty plugs will invalidate test results.
3. Close all openings in the line with watertight seals (Test Stoppers) ensuring against
movement. i.e. all plugs held firmly in position.
4. Ventilating valve should be fixed at the high point of the section.
- All the joints of the pipeline shall be able to withstand a pressure of a minimum of 5 m head of water, above the crown of pipe at the highest point of the pipeline without leakage. A layer of embedding soil equal to the diameter of the pipe shall be laid over the pipe to prevent the lifting of the pipe while applying test pressure. However, all the joints shall be left open for the purpose of inspection for leakage if any. All branches and open ends shall be closed with stoppers, secured with longitudinal braces/thrust block before testing begins.
- Water shall be filled from the lowest point and air allowed to escape through an air vent fixed for the purpose at the high points of the pipeline section under test. The diameter of the air vent shall be about one and half times the diameter of the water inlet pipe to allow easy escape of air. No entrapped air shall remain in the pipeline while testing.
- A pressure of 5 m head of water shall be maintained for one hour to allow initial absorption of water. After that, the test pressure shall be maintained for 15 min and water added shall be measured. If water consumption in 15 min does not exceed 0.1 l/m2 of wetted inner pipe surface and if there is no visible leakage through joints, the pipeline shall be treated as passed.
Infiltration Testing a Pipeline:
- This test method defines procedures for hydrostatic infiltration testing of new installations of vitrified clay pipelines, to demonstrate the structural integrity of the installed line as per ASTM C 1091 – 03a.
- This test method is suitable for testing gravity-flow pipelines constructed of vitrified clay pipes or combinations of clay pipes and other pipe materials.
- This test method is applicable to the testing of the pipelines only.
- The upper ends of the sewer and service connections shall be closed sufficiently to prevent the entry of water and pumping of groundwater shall be discontinued until the groundwater-surface reaches its natural level before beginning the infiltration test.
- The dewatering system shall be stopped, but not be removed until the infiltration test has been successfully completed or as otherwise permitted by the Consultant/Engineer.
- The hydrostatic infiltration test procedure is applicable where the measured water table is 2 ft (610 mm) or greater above the pipe barrel at the lower manhole of the test section. Where the groundwater elevation is indeterminate, less than 2 ft (610 mm) above the top of the pipe barrel, or the line is partially below the water table, use a combination of both the air test and infiltration procedure.
- Note 1-The most practical method for testing is Air Test Method and is recommended.
- However, where groundwater is present and meets the criteria established in this procedure, the infiltration test procedure outlined in this practice is recommended.
- Note 2- What can be called false infiltration represents condensate on the pipe walls.
- The infiltration shall not exceed 6 liters per mm diameter per kilometer per day of the portion of a sewer being tested, including the length of service connection entering that section.
- The total length tested in one section shall not exceed 400 m in length. This length is dependent upon the type of deflection measuring equipment proposed by the Contractor if flexible pipes are used.
- No gravity pipeline will be accepted if the total infiltration exceeds the above-mentioned limit and joints will not be accepted if, during an internal inspection, any infiltration is visible.
- If the test section includes more than one pipe size, calculate the allowable test rate for each size and add to arrive at the total allowable test rate for the test section.
- External drainage pipelines shall be tested for infiltration after backfilling. All inlets to the system shall be effectively closed, and any residual flow shall be deemed to be infiltration.
- The pipeline shall be accepted as satisfactory if the infiltration, including infiltration into manholes, in 30 minutes does not exceed 0.5 liters per linear meter per meter of the nominal bore. This relationship in equation format, with water infiltration measured in liters, can be written as follows: Maximum volume of infiltration over a 30 minute period = 0.5 x L x D Where: L = pipe diameter (m) D = Length of test section (m)
- CCTV survey shall be carried out on a representative sample of no more than 12% of the length of constructed pipelines if the ConsultanUEngineer’s Representative requires.
- In case this survey indicates sections of the pipeline fail to meet the specification requirements, undertake additional CCTV after remedial works will be carried out.
Setting-up of Equipment
- Place visible signage i.e. “System Under Pressure”, “Keep Away”, “Danger”, “Caution”.
- Warning notices and barricades (if deemed necessary) will be used to identify the system under test.
Clean-up and restoration
- After a successful test, remove carefully all temporary plugs.
- Remove warning signage and temporary barricades in a safe and orderly manner such that the work area is restored as is prior to conducting the test.
- Clean the work area thoroughly prior to transfer to another test location.
Health, Safety and Environment -Method Statement Of Storm Drainage System
A. HSE Risk Assessment
B. Permit and Licensing Requirements
The required permit to work shall be obtained prior to the commencement of work. This shall be
coordinated with HSE. Site interface permits to be taken from other contractors before placing
pipe at tie-in point to reconfirm IL and coordinates.
C. Pre-Start Safety Briefing Arrangements
C.1 Protective and Safety Equipment
All workers Involved shall be equipped with adequate PPE as stated below:
- Safety Helmet with Company Logo
- Safety Boots
- High Visibility Vest
- Safety Goggles
- Hand Gloves
- Proper safety harness
C.2 Information to Personnel
- Safety Induction
- Job training
All the personnel involved in this task shall be provided training and only trained
personnel shall be authorized to work around this area.
C.3 Special Safety Requirements:
- All necessary personal/protective equipment (PPE), as well as harness, be provided.
- Rigging Team, wearing distinctive vests, shall be assigned to help operators maneuver their equipment.
- The equipment operators shall possess the required licenses and certificates.
- The required permit to work shall be obtained prior to the commencement of work.
- The project safety officer is responsible along with the project zone site engineer for ensuring that all operations are carried out with due regard to the safety of all project personnel & property.
- Working at height to be monitored with due care.
- The contractor must provide a safe place of works, with safe access and egress. Provide a safe working environment that is without risk to health.
Quality Assurance and Quality Control-Method Statement Of Storm Drainage System
A. Quality Assurance Requirements
The contractor shall provide the required documents for the Consultant’s approval prior to initiate
with the execution of this activity as per project specification requirements.
The Quality Control requirement shall include related ITP’s and other related documents
B. Quality Assurance Process
The contractor shall notify the Engineer 24 hours in advance prior to the start of activity and
Comments from the Site Instruction will comply with the satisfaction of the consultant.
The contractor shall consult the public utility authorities not less than one month before it is
proposed to commence work to ascertain whether any underground installations will be
affected by the proposed work, in which event the contractor shall make all necessary
arrangements with the public utility authorities to safeguard the installation.
C. Follow up and Evaluation
Follow up on quality performance shall be carried out through an in-house monitoring system
such as progress reporting to the planning department, daily, weekly, and monthly reports
generated by the planning department to closely monitor site performance.
All the above shall be conducted in close coordination with the quality department to
monitor any deviations from the Quality Management System requirement and induce
corrective actions whenever required to eliminate non-conformance or quality deviations.