- 1 Pipelines
- 1.1 Scope
- 1.2 General
- 1.3 Materials
- 1.3.1 Ductile Iron Pipes and Fittings
- 1.3.2 Steel Pipes and Fittings
- 1.3.3 Asbestos Cement Pipes and Fittings
- 1.3.4 Polyvinyl -Chloride Pipes
- 1.3.5 Repair of Coating and Linings
- 1.3.6 Joints - General Requirements
- 1.3.7 Push-on Joints
- 1.3.8 Mechanical Joints
- 1.3.9 Flanged Joints
- 1.3.10 Welded Joints
- 1.3.11 Screwed Joints
- 1.3.12 Thrust Resisting
- 1.4 Handling and Storage
- 1.5 Cutting of pipes
- 1.6 Installation of Pipes - Generally
- 1.7 Installation of Pipes Underground
- 1.7.1 Lowering of Pipes into Trench
- 1.7.2 Cleaning of Pipes and Fittings
- 1.7.3 Laying of Pipes
- 1.7.4 Coordination with Excavation
- 1.7.5 Socket Ends
- 1.7.6 Unsuitable Conditions
- 1.7.7 Pipe Insulation
- 1.7.8 Buried Ductile Iron Pipes
- 1.7.9 Bedding to Pipes
- 1.7.10 Concrete Bed and Surround
- 1.7.11 Installation of Pipes above Ground
- 1.7.12 Installation of Service Connections
- 1.8 Installation of Valves and Fittings
- 1.9 Testing, Disinfection and Rinsing
- 1.10 Markers
This section covers the requirements for pipelines outside structures. The specification for pipe work within structures and up to 600 mm outside the face of structures is covered in the General Specification for Mechanical Works.
The Contractor shall supply and install all piping, valves, fittings and all other appurtenances as required to provide a complete functioning system. The Contractor shall permit access at all reasonable times to those parts of manufacturer's work where pipes and fittings are being made or tested. The Contractor shall supply a signed test certificate to confirm that each pipe and fitting conforms to the appropriate DIN standard specified hereafter in all respects, irrespective of whether tensile of any other tests have been carried out in the presence of the Engineer.
1.3.1 Ductile Iron Pipes and Fittings
Ductile iron pipes and fittings shall be in accordance with DIN 2410, DIN 28500 and DIN 28600 up to DIN 28648. Standard pipes shall be in any case not less than 5.5 m in length. Ductile iron pipes and fittings shall be mortar lined to AWWA C 104, double thickness. Rubber joint rings shall be in EPDM rubber.
1.3.2 Steel Pipes and Fittings
Steel pipes and fittings shall be in accordance with DIN 2401, DIN 2402, DIN 1626, DIN 1629 and the other appropriate DIN standards for fittings.
1.3.3 Asbestos Cement Pipes and Fittings
Asbestos cement pipes and fittings shall be in accordance with DIN 2401, DIN 2402, DIN 2410, DIN 19800 and DIN 19802 up to DIN 19808. Cast iron fittings shall be obtained through the manufacturer of the asbestos-cement pipes. All asbestos-cement pipes shall be jointed by flexible detachable ‘Gibault’-type couplings.
1.3.4 Polyvinyl -Chloride Pipes
Polyvinyl-chloride pipes and fittings shall be in accordance with DIN 2401, DIN 2402, DIN 8063,DIN 16450, DIN 16451, DIN 16929 and DIN 19532.
1.3.5 Repair of Coating and Linings
Any pipe with lining that is broken, defective, or not adhering in all places to the metal interior of the pipe, or not otherwise in accordance with the Specification shall be rejected. Remedial lining operations may be carried out by a method that has been approved in writing in advance by the Engineer. The standard of the remedial lining shall satisfy the requirements of the Specification. Damage to external coatings shall be made good to equivalent for the original coatings applied by the manufacturer and to the satisfaction of the Engineer. Exposed surfaces shall be finish painted according to the manufacturer's instructions, or as directed by the Engineer, using a corrosion resistant paint.
1.3.6 Joints - General Requirements
In general all jointing shall be in accordance with the manufacturer's instructions. Before making any joint the Contractor shall ensure that the interior of each pipe or valve is clean and it remains clean. Immediately before starting a joint the Contractor shall clean the end of each pipe to be jointed and shall otherwise specially prepare the ends for jointing as may be necessary for the particular kind of joint. All mechanical joints shall be cleaned and have their paintwork or coating made good before assembly. The Contractor shall use only the proper jointing parts as specified and obtained through the suppliers of pipes or valves. All joints shall be accurately made and shall be capable of passing tests for individual joints and for the completed pipeline.
1.3.7 Push-on Joints
A penetration gauge shall be used to check each joint after assembly, to ensure that the rubber ring is properly seated. When it is desired to deflect push-on joint pipe in order to form a long-radius curve, the amount of deflection shall be directed by the instructions of the manufacturer and approved by the Engineer. It is important that in making the joint the pipes are maintained in a straight line and the deflection introduced after the joint has been assembled.
1.3.8 Mechanical Joints
Bolts shall be tightened alternately on opposite ends of joint diameter and in rotation around the pipe. When properly assembled the gland shall be equidistant from the socket face at all joints. Under no conditions shall extension wrenches or pipe-over-handle or ordinary ratchet wrenches be used to secure greater leverage.
1.3.9 Flanged Joints
Normal flanges shall be integrally cast with the body of the pipe and shall be of the raised face type. Flanged joint pipe shall be firmly and fully bolted with machined bolts provided by the manufacturer. Gaskets shall be used at all flanged joints. Slip-on flanges shall be double welded to the pipe with a strength weld joining the flange hub to the pipe and a seal fillet weld inside the flange at the pipe end. All flanges of the same diameter shall be compatible.
1.3.10 Welded Joints
Welding of joints, where required or directed, shall be in accordance with DIN 19630, DIN 2470 and DIN 2559 (butt welding).
1.3.11 Screwed Joints
All pipe thread shall conform to the appropriate DIN standard mentioned above. All threads for screwed joints shall be clean, machine cut, and all pipe shall be reamed before installation. Each length of pipe shall be up-ended and rapped to dislodge dirt and scale. Screwed joints shall be made up with good quality thread compound applied to the male thread only. After having been set up, a joint must not be backed off unless the joint is completely broken, the threads cleaned, and new compound applied. All screw joints shall be airtight.
1.3.12 Thrust Resisting
To prevent the main from pulling apart joints at certain pipe sections, and where those sections are not otherwise anchored, the Contractor shall use fittings with thrust resisting joints in accordance with the appropriate DIN standard.
1.4 Handling and Storage
The Contractor shall only use such methods and equipment as will prevent damage to the pipes and valves and to any sheathing lining or paintwork, and such methods shall include the use in appropriate cases of pipehooks, lifting beams, reinforced canvas slings, protective padding, struts, cradles and pipe trailers. Temporary packing, coverings or crated provided by the supplier for the protection of pipes and valves in transit shall not be removed (except for purposes of inspection after which they shall be replaced) until immediately before the pipe or valve is installed, and shall then be disposed of by the Contractor. No pipe shall be moved by rolling save over suitable timber planking so arranged as not to damage the pipe or its sheathing.
1.4.2 Ductile Iron Pipes
The pipe shall be handled in such a way to prevent damage to the cement lining or exterior coating and any damage shall be repaired promptly before installation. For large diameter ductile iron pipes (greater than 600 mm) the ends of the pipe shall have wooden stiffeners at quarter points of the spigot end to prevent any distortion of the pipe at its end. This blocking shall remain in the pipe until it is ready for installation. The pipe shall be stored on site without stacking unless blocking is provided between layers of pipes. For stacking see the table below (item 10.4.6).
1.4.3 Steel Pipes
The ends of the pipes shall have wooden stiffeners installed inside the pipe at quarter points at both ends of the pipe. This blocking shall remain inside the pipe until the pipe has been installed. The Contractor shall prevent any fires from being made beside or adjacent to the pipe. While the pipe is stored on site, the pipe sections shall be kept free of any objects being stored inside and the larger diameter pipes shall not be occupied by workmen for any purpose. Stacking of pipe will be allowed only if blocking is provided between pipes. For stacking see the table below (item 10.4.6).
1.4.4 Asbestos Cement Pipes
While the pipe is stored on site the pipe sections shall be kept free of any objects being stored inside and the larger diameter pipes shall not be occupied by workmen for any purpose. Pipes must not be stored on site with stacking.
1.4.5 Polyvinyl-Chloride Pipes
Careful consideration must be given to the handling and temporary storage on site of PVC pipes and fittings. The pipe must be stored out of any direct sunlight. Extreme care shall be taken to prevent any scarring or nicking of the pipe and from bearing on sharp objects. Jointing rubber gasket type pipes into the socket shall be achieved by applying pressure against the opposite end of the pipe being installed. A wooden block or other suitable device shall be used to prevent any damage to the socket being pressed. No blocking will be allowed under the pipe and it shall bear evenly along its entire length on the bedding material.
1.4.6 Stacking Pipes
When not otherwise required by the pipe manufacturer, pipes when stacked may be nested between each other or square stacked with timber bearers between each layer and shall be supported on timber bearers clear of the ground.
The maximum number of layers in any stack of pipes shall be as follows: Nominal diameter (mm) Number of Layers in Stack 150 14 200 12 250 10 300 8 350 7 400 7 450 6 500 6 600 4 700
All rubber joint rings and other items shall be kept out of direct sunlight.
1.4.7 Taking Delivery of Pipes and Valves Provided by Contractor
The Contractor shall take delivery of and off-load pipes and valves which he is required to provide at times and at locations or storage areas on or about the site to be arranged by him with his suppliers. Any such location or storage area shall be arranged for by the Contractor at his own risk and expense.
1.4.8 Transport on Site
After pipes and valves have been delivered to and offloaded at delivery locations as aforesaid, the Contractor shall make all arrangements for subsequent transport and handling on or about the site to the point of installation, including where necessary any movement into and out of temporary storage.
1.4.9 Temporary Storage
The Contractor shall take into temporary protective storage all pipes and valves not required for immediate installation in the works. Valves shall be stored under cover until they are required for installation and particular care shall be taken for the protection of any associated electrical or mechanical equipment. The period between taking delivery of a pipe and the completion of its installation shall be kept to a minimum. Any period during which the pipes are strung out along the pipeline or placed alongside the works awaiting installation shall also be kept to a minimum and if this period exceeds one month pipes shall be raised at least 75 mm from the ground on timber bearers. Jointing parts and materials shall in any case be stored under cover as for valves.
1.4.10 Inspection at Time of Installation
Any special material required for the repair of pipe sheathing or lining shall be obtained from the pipe supplier and shall be used with due regard to his recommendations. The Engineer may himself, and without thereby relieving the Contractor of any of his obligations, inspect and test the pipes and valves by any means he considers appropriate and any damage discovered by such inspection shall be repaired by the Contractor as aforesaid. The Contractor shall remove from the site and shall provide a replacement for any pipe or valve which in the opinion of the Engineer is so badly damaged as to be unfit for repair on the site.
1.5 Cutting of pipes
1.5.1 Ductile Iron Pipe
Any cutting of pipe shall be made by use of cutting tools recommended by the manufacturer and approved by the Engineer. Cutters utilizing compression will not be allowed for cutting ductile iron pipe. All cuts shall be clean and perpendicular to the axis of the pipe. Any damage to the linings shall be repaired.
1.5.2 Steel Pipe
All field cutting of the pipe shall be minimized. When such cutting is required it shall be done by a suitable cutting machine, leaving a. smooth cut at right angles to the axis of the pipe. Care shall be taken not to damage the coating or lining of the pipe.
1.5.3 Asbestos Cement Pipe
Field cut ends shall be smooth and at right angles to the centreline of the pipe. Tapering of cut ends shall also be made in accordance with the manufacturer's recommendations.
1.5.4 Polyvinyl -Chloride Pipe
Cutting of the pipe shall be kept to a minimum. When cuts are necessary they shall be perpendicular to the axis of the pipe and smooth. Cuts shall be made in accordance with the pipe manufacturer's recommendations. Cut ends shall then be tapered and the bevelled end shall be exactly the same as the spigot end of the pipe as manufactured at the factory. Solvent welds which are only allowed for service connections shall be made in strict accordance with the manufacturer's recommendations and utilize only solvents furnished by the manufacturer. In addition, it will be necessary to install underground piping so that the offset from true horizontal alignment is not more than 30 cm in 30 metres of the laying length. Care shall be taken to ensure that the temperature of both sections of pipe being joined are the same.
1.5.5 Closing Lengths
Pipes which are required to be cut to form closing pieces in any portion of the pipeline or to terminate in manholes or other parts of the works shall not be cut until after all adjacent pipes have been installed and jointed. The Contractor shall determine the length of each closing piece and the required angle and shape of the cut. The cut shall be neatly performed and the end of the pipe shaped up and trimmed so as to ensure an accurate joint or termination as the case may be. Any damage to sheathing coating or lining shall be made good. The unused part of any cut pipe shall be the property of the Contractor and shall be disposed of by him off the site unless with the Engineer's approval it can be used elsewhere in the works.
1.6 Installation of Pipes - Generally
Unless specified otherwise pipes shall be installed singly and shall be jointed at the time of installation or afterwards if appropriate. The pipes shall be accurately installed to the lines, levels, grades and positions set out by the Contractor. Changes in direction or in grade of the pipeline shall be carried out by making use of any permissible deflection of joints between straight pipes or by the introduction of special bends as may be directed by the Engineer.
1.7 Installation of Pipes Underground
1.7.1 Lowering of Pipes into Trench
Proper instruments, tools and facilities satisfactory to the Engineer shall be provided and used by the Contractor for the safe and convenient performance of the work. All pipes, fittings, and valves shall be carefully lowered into the trench piece by piece by means of derrick, rope, or other suitable tools or equipment, in such a manner as to prevent damage to pipes, valves, fittings, etc., and protective coatings and linings. Under no circumstances shall materials be dropped or dumped into the trench. If damage occurs to any pipe, fitting, valve or accessory in handling, the damage shall be immediately brought to the Engineer's attention. The Engineer shall prescribe corrective repairs or rejection of the damaged items.
1.7.2 Cleaning of Pipes and Fittings
All lumps, blisters, and excess and fittings coating shall be removed from the socket and spigot end of each pipe. The outside of the spigot end and the inside of the socket shall be wiped clean, dry and free from oil and grease before the pipe is laid.
1.7.3 Laying of Pipes
Every precaution shall be taken to prevent foreign material from entering the pipe while it is being placed in the line. During laying operations no debris, tools, clothing or other materials shall be placed in the pipe. As each length of pipe is placed in the trench, the spigot end shall be centred in the socket and the pipe forced home and brought to correct line and grade. The pipe shall be secured in place with approved backfill material tamped under it except at the sockets. Precautions shall be taken to prevent dirt from entering the joint space. At times when pipe laying is not in progress, the open ends of pipe shall be closed by a means approved by the Engineer.
1.7.4 Coordination with Excavation
The construction of the pipeline in trenches shall be coordinated with the excavation and refilling of trenches so as to ensure expeditious completion of the whole operation.
1.7.5 Socket Ends
Pipe shall be laid with socket ends facing in the direction of laying, unless directed otherwise by the Engineer. Where pipe is laid on a grade of 10 % or greater, the laying shall start at the bottom and shall proceed upward with the socket ends of the pipe upgrade.
1.7.6 Unsuitable Conditions
No pipe shall be laid when, in the opinion of the Engineer, trench conditions are not suitable.
1.7.7 Pipe Insulation
Wherever it is necessary to join pipes of dissimilar metals pipe insulation shall be installed as approved by the Engineer.
1.7.8 Buried Ductile Iron Pipes
Ductile iron pipelines, where buried, shall be protected with proprietary polyethylene sleeving according to DIN 30674. The sleeving shall be provided by the Contractor. Before installation of each pipe and fitting the Contractor shall apply the sleeving ensuring that it is correctly positioned relative to the spigot end of spigot and socket pipes, and terminated behind the socket. The sleeving shall be pulled tightly around the barrel of the pipe and any surplus folded over at the crown of the pipe to form a triple thickness layer of film. Plastic adhesive tape shall be used to secure the folds on the crown of the pipe at least four positions along the length of the pipe, and the ends of the sleeving shall be sealed to the pipe by taping around the whole circumference. The sleeving at joints, tees and tapers shall be completed by using the sleeving cut to form sheets to wrap around the joints, tees and tapers and secured with the adhesive tape, overlapping onto the sleeving of the adjacent pipe of fitting. Polyethylene sleeving shall not be applied to those sections of pipelines exposed either above ground or in chambers or to be cased in concrete. At such places the sleeving shall be terminated at a point 500 mm below the surface of the ground or at the external face of the valve chamber structure or the face of the concrete surround, whichever is applicable.
1.7.9 Bedding to Pipes
Refer to the General Specification for Earthworks, Part 2.
1.7.10 Concrete Bed and Surround
If necessary, pipes shall be bedded haunched or surrounded in concreted. Concrete shall be unreinforced and shall comply with the requirements of the General Specification for Concrete, except that vibration will not be required. Any formwork required shall be of class F1 to the requirements of the General Specification for Formwork. Such concrete shall not be placed until the joints at each end of the pipe have been completed. Each pipe shall be supported on at least two purpose made precast concrete blocks, which shall be left in place, and the full width and depth of bedding concrete shall be placed and carefully punned beneath the pipe followed at once by the addition of any haunching and surround concrete. Unformed surfaces shall be of spade finish. The pipe shall be prevented from floating or other movement during concreting. Where necessary, the continuity of concrete bed haunch or surround to pipe with flexible joints shall be broken at each joint.
1.7.11 Installation of Pipes above Ground
Pipes shall be installed above ground where required for river crossing and bridge crossing. The Contractor shall design, install and furnish all pipe hangers and supports to the approval of the Engineer. The Contractor shall install sleeves or wall casting or all pipes passing through masonry walls and concrete floors or walls and concrete inserts for hangers and supports, in accordance with the appropriate specification as soon as forms are erected and before concrete is in place. All pipes shall be rigidly supported by approved hangers, inserts, or supports with adequate provisions for expansion and contraction. Pipes shall not be supported from other pipes or from stairs, ladders, or walkways unless specifically directed by the Engineer. Where pipes are installed on structural steel supports, blocking of pipe shall be provided to avoid lateral pipe movement. All vertical pipes shall be supported at sufficient intervals by approved pipe collars, clamps, brackets, or wall rests, and at all points necessary to ensure rigid construction.
1.7.12 Installation of Service Connections
Service connections comprise the tapping unit at the main, the subsequent tertiary pipe and the actual service line to the house. The laying of service connections shall comply in general with the procedure specified previously. Service pipes shall be laid at sufficient depth to clear any obstructions such as stormwater drains, service ducts, irrigation channels, house connection drains and other underground installations. Caps shall not be removed from pipe ends until they are ready for jointing. Pipes shall be laid on firmly compacted beds, so that they rest evenly and uniformly. The connections shall be pressure-tested by applying the full mains pressure before backfilling the trench. If pipes are not laid in a separate concrete channel they shall be laid in the trench with a minimum of 750 mm of cover below the surface of the ground. The Contractor shall ensure that no water is allowed to enter the trench, and that no water or extraneous matter enters the pipes during laying.
1.8 Installation of Valves and Fittings
Valves, fittings, plugs, and caps shall be set and joined to pipes in the manner specified above for cleaning, laying and joining pipes. The Contractor shall furnish all components required for construction of valve chambers and valve control access to buried valves, including cast iron covers.
1.8.2 Air Valves
Air valves shall be installed at all high points when necessary.
Washouts shall be installed complete at all low points where necessary. Washouts shall be formed by a standard T-piece with the drain branch. The outlet of the drain must be directed to the lowest ground level, in such a way that no wash-aways of the main pipe can occur. The drain pipe of washouts shall not be connected to any sewer, submerged in any stream, or be installed in any other manner that will permit back-siphoning into the distribution system. If drainage by gravity is not possible the Contractor shall consider the installation of sufficient drainage pits including complete pumping equipment.
1.8.4 Fire Hydrants
Underground fire hydrants shall not be installed with their tops deeper than 450 mm below the surface. If the pipe is laid in such a way that the hydrant would be positioned deeper than 450 mm1 the vertical pipe to the fire hydrant T-piece must be extended by a flanged pipe section. The vertical pipe section to standpost hydrant shall be of sufficient length to allow the prescribed position of the hydrant above ground. All extension pipes must be cut and welded.
1.8.5 Isolation Valves
Isolation valves shall be installed as shown on the approved drawings. Special attention shall be drawn to clean and careful installation of valves. Any foreign matter resting in valve-seats shall be removed to ensure efficient operation of valves. All isolation valves shall be installed on concrete bases and joined with dismantling pieces. The top of the operating stem shall not be deeper than 600 mm below the surface, otherwise the stem shall be extended.
1.8.6 Bends and Fittings
Pipelines shall be laid in straight lines with gradual changes being taken up at the joints as approved by the manufacturer. Where a sudden change of direction cannot be avoided, bends shall be used. The location of bends, tees, and other fittings shall be determined in the field in close cooperation with the Engineer.
1.8.7 Blind Ends
All pipe ends that shall be connected to future extensions plugs, caps or blind flanges shall be installed and secured in place.
1.8.8 Valve Chambers and Similar Structures
The surface valve box shall not transmit shock or stress to the valve and shall be centred and plumb over the operating nut of the valve. The lid of the box shall be flush with the surface of the finished pavement or such other level as directed by the Engineer. Valve chambers shall be constructed of reinforced concrete. A precast concrete chamber may be installed upon the Engineer's approval. Cover frames shall be set in cement mortar. The construction of a valve chamber shall include the supply and installation of step irons, which shall be installed in all manholes deeper than 0.6 m. They shall be spaced 0.3 m in al vertical directions and 0.2 m in a horizontal direction. The valve nut shall be readily accessible for operation through the opening of the manhole or the surface box, which shall be set 0.3 m higher than the adjacent surface of the finished pavement. Valves, which will be installed in the ground, shall be provided with extension spindles and protection tubes up to the surface box.
1.8.9 Anchor Blocks
All movement of the pipeline shall be prevented by concrete anchor blocks. The Contractor shall design, supply and construct all necessary anchor blocks. Anchor blocks shall be provided for all branches, caps, tapers, bends, reducers, valves, hydrants, etc., and shall be placed in such a manner to allow easy access for removal of valves, hydrants, fittings, etc. The quality of concrete shall be of class B 25 and reinforced anchor blocks shall be of class B 25. Thrust forces, calculation and sizing of anchor blocks shall be taken from the manufacturer's instructions for a particular pipe material; pipe pressure for calculation purposes shall be the field test pressure. Thrust blocks shall be cast between the fitting which is to be supported and the undistributed wall of the trench. The concrete shall be placed around the fitting in such a way that the couplings are not covered or fixed by it to allow for flexibility and to provide access to the collars for replacing when necessary. Before casting concrete, bituminous felt shall be wrapped around the fittings at the interfere between concrete and the fitting. Where required, anchor clamps shall be cast into the anchor blocks.
1.8.10 Concrete Protection
Pipelines running under drain channels, streams or roads shall be encased in concrete class B 25 in full length, if not otherwise prescribed. Before the concrete is placed, the pipe and all fittings shall receive a double wrapping of bituminous felt. The minimum thickness of the concrete encasement around the pipeline shall be one quarter of the pipe diameter, but at least 15 cm. The concrete shall be reinforced by steel bars as calculated by the Contractor and approved by the Engineer. Where pipelines cross over drains or other utilities, and where the soil cover is not sufficient and a concrete encasing is not advisable, a reinforced concrete slab shall be placed 100 mm above the top of the pipe. This lead spreader slab shall be 100 mm thick with a width 3 times the outside diameter of the pipe. The slab may not be cast before the backfilled ground has been compacted. Concrete shall be of class B 25.
1.8.11 Railway Crossings
Where the pipeline crosses any railway, it shall be installed in accordance with the requirements of the related authorities. The Contractor shall be responsible for coordinating this work with the National Railway Company and other related authorities.
1.8.12 Metal Tape
Non-metallic pipes shall be laid with a continuous metallic tape for simple detection after installation. The tape (or wire) shall be or corrosion resistant metal and shall be placed on top of the pipe.
1.9 Testing, Disinfection and Rinsing
All pipelines and all works shall be subject to pressure and leakage tests after being laid and installed before commissioning. Pressure and leakage tests will be carried out simultaneously.
The test shall be performed in accordance with DIN 4279. Where lines cannot be tested under pressure in a single operation, they shall be tested in sections (section test). The length of the sections shall be at the discretion of the Contractor subject to approval by the Engineer. The results of the tests, specifying the layout of sections of system, pipes and fittings tested including all relevant data of testing as weather, time, duration, filling time, pressure, etc., shall be produced in form of a report by the Contractor to be approved by the Engineer. This report shall not relieve the Contractor of his responsibility of care and maintenance of the system until the date of the Maintenance Certificate.
1.9.3 Cleaning Out after Testing
After the completed pipeline is tested, approved and backfilled and the Contractor has removed all temporary works and has reconnected any parts temporarily removed from the pipeline, the Contractor shall finally clean out the whole pipeline and flush it through with water. The Contractor shall be liable to the Employer for any damage caused to the pipeline or to pumps and other equipment of the Employer as a result of foreign matter of any kind not having been cleaned out of the pipeline before it is handed over to the Employer.
After cleaning out, a disinfection shall be performed in the following manner: after flushing the pipes the system shall be drained completely, all valves shall be closed carefully and the system filled with a strong chlorine solution of about 50 ppm free chlorine. This solution shall remain in the system for at least 24 hours uninterruptedly and still show a chlorine content of at least 25 ppm. After draining the solution the system shall be rinsed with potable water with a free chlorine content of 2 to 4 ppm as ordered by the Engineer which is to be tested at the inlet by an orthotolidine reagent with a colour scale. After 24 hours, water samples taken at any outlet of the pipeline shall show the same chlorine content as charged. This proves adequate disinfection and rinsing. In case of failure of the test, chlorination and rinsing shall be repeated until fulfilment of the requirements. After completion of disinfection and rinsing the Contractor's results shall be reported by the Contractor in writing and signed by the Contractor and the Engineer. The Contractor shall provide at his own expense such sampling points as the Engineer may direct if permanent points are not available or suitably located.
1.9.5 Water for Testing and Cleaning
The Contractor shall provide all water required for testing and cleaning the pipeline, and shall use only potable water.
Markers for pipelines, valves and hydrants shall be made out of concrete class B 25 prefabricated with the following dimensions: 30/140/10 cm with chamfered corners and placed in a concrete bed of 50/50/50 cm so that the marker protrudes 90 cm. Figures and letters shall recess about 8 to 10 mm from the surface and give the following information for pipelines: reference of line, diameter, progressive distance; for valves: number of valve and offset; for hydrants: number of hydrant and offset.