DUBLIN CITY COUNCIL WATER SERVICES DIVISION CODE OF PRACTICE FOR THE LAYING OF DISTRIBUTION WATERMAINS

Transcription

1 DUBLIN CITY COUNCIL WATER SERVICES DIVISION CODE OF PRACTICE FOR THE LAYING OF DISTRIBUTION WATERMAINS 1. GENERAL June 2009 Contractors have a responsibility to comply with all national legislation and any Code of Practice called up by that legislation, the provisions of which take precedence over this Specification. Contractors and their employees are expected to be competent in the basic elements of designing and constructing water systems such as water main and service pipe laying; service connections; health and safety; understanding materials selection; regulatory requirements; principles of water supply hygiene; customer care and environmental issues. This specification refers to watermains up to and including 300mm in diameter. The Contractor shall submit an as constructed drawing to the Water Services Division, in hard copy and DXF CAD format, within four weeks of completion of the watermain. 2. PLANS The Contractor shall apply for a connection from the existing watermain before construction commences on site. The application shall involve the submission of drawings and other information for approval as specified on the Application Form. Application Forms are available from the Dublin City Council website > Your Drinking Water > Connect a property to the water supply. 3. INSPECTION A Water Services Division representative may inspect works from time to time to ensure that: Watermains have been laid in accordance with this Specification. Pressure, chlorination and bacteriological tests have been carried out and approved. Specific testing requirements may be specified for individual works. 4. MATERIALS No materials shall be used without the prior approval of the Water Services Division. It is the responsibility of the Contractor to ensure that all materials/fittings to be used on the site have been approved for use by the Water Services Division in advance of work commencing. A copy of the Water Services Division Standard Details is available on request. In the event that ground conditions in any part of the site prove to be anything other than inert material, the Contractor shall inform the Water Services Division accordingly and take whatever precautions are deemed necessary by the Water Services Division to deal with the situation. These precautions may include, but not be restricted to, the laying of watermains 1

2 which are specially designed for use in contaminated ground. Such mains shall also be laid in specially designed trenches as approved by the Water Services Division. 5. PIPES & SPECIAL CASTINGS Pipes shall be only MOPVC (up to and including 200mm), CPE/PVC alloys (up to and including 200mm), Ductile Iron, MDPE or HPPE. All plastic water pipes shall be blue in colour. MOPVC pipes shall conform to the UK Water Industry Specification No and manufacturers shall operate a quality system in compliance with BS 5750 Part 2 (EN29002). CPE/PVC alloy pressure pipe shall conform to BS PAS 27. All fittings should conform to this standard also. Ductile iron pipes shall conform to Class K9 of EN 545. Ductile iron fittings shall be Class K9. All ductile iron pipework shall be coated internally with a centrifugally applied cement mortar lining containing a sulphate resistant cement and shall be sealed with an approved bitumen or epoxy resin seal coat in accordance with BS 4722: External protection shall include a zinc coating to EN 545 under bitumen based coating to BS 3416: MDPE pipes should be of type PE-80 and have an SDR rating of 11. They shall conform to IS EN 12201: Part 2: HPPE pipes should be of type PE-100 and have an SDR rating of 17. They shall conform to IS EN 12201: Part 2: Service Pipes & Fittings Service pipes and fittings laid underground should be of blue polyethylene to I.S. EN MDPE and HPPE service pipes and fittings shall conform to: I.S. EN : Plastics piping systems for water supply-polyethylene (PE) part 2: pipes. I.S. EN : Plastics piping systems for water supply-polyethylene (PE) part 3: Fittings. UK WIS : Specification for PE 80 and PE 100 spigot fittings and drawn bends for nominal sizes up to and including Copper service pipes may be laid in the ground in certain circumstances. Copper pipe for use in ground conditions should be type R220 (annealed) or R250 (half hard) and comply with I.S. EN Copper pipe joints for use underground should conform to I.S. EN capillary soldering or I.S. EN : Type B; manipulative compression fittings. Copper alloy fittings for use underground shall be made from gunmetal to I.S. EN 12165, I.S. EN 12163, I.S. EN or I.S. EN material CZ 132 (resistant to dezincification) or be tested for dezincification resistance in accordance with I.S. EN ISO 6509:1995. The sizing of service pipes to any premises and the approval of pipes and fittings for this purpose must be approved in advance by Water Services Plumbing Inspectorate. 5.2 Boundary Box All service pipes shall include the installation of an approved boundary box with integral stopcock (note that the use of the traditional stopcock has been discontinued). The boundary box shall be a telescopic type self contained chamber system with Class C load bearing capacity (capable of supporting a 5 tonne wheel load). Contractors shall consult with the DCC Water Services Division in relation to approved types of boundary box. The only approved types of boundary box at the moment are the Talbot range and the Atplas range. 2

3 5.3 Sluice Valves Sluice valves shall be double flanged with ductile iron resilient seal gate valves and shall comply with the relevant requirements of BS : 2004 Type B and have the BS Kitemark. The number of turns to fully open/close the valve must be n = 2N + 1 where N = the equivalent diameter in inches. All flanges shall be drilled to P.N. 16. The spindle shall be fitted with a cast iron oval false cap (complete with grub screw) of standard Dublin City Council pattern. All sluice valves shall be ANTI-CLOCKWISE CLOSING. 5.4 Hydrants (80mm) Hydrants shall be manufactured in accordance with BS 750: 2006, Type 2 and shall incorporate a screw-down valve, underground, guide in head type, with bayonet lug outlets and false spindle cap of standard Dublin City Council pattern. A contractor may not use hydrants (which are provided for emergency supply) without the written permission of Dublin City Council The hydrant valve shall be ANTI-CLOCKWISE OPENING i.e. the opposite of a sluice valve. Note: Both sluice valves and hydrants shall be coated with an electrostatic epoxy powder spray, or bitumen trichloroethylene solution to U.K. National Water Council and Dublin City Council approval. 5.5 Hydrant and Meter Chambers Chamber floors shall be Grade C25/30 concrete with 215mm thick solid block walls. Alternatively, Polypit Modular Chambers or similar approved may be used. 5.6 Surface Covers Valves and hydrants when installed shall be covered with approved heavy-duty metal surface covers to I.S EN 124: These approved metal covers shall conform to the Dublin City Council Specification for valve and hydrant covers. Where a chamber is located in grass, the cover shall be surrounded by a concrete plinth 200mm all round and 100mm deep. Concrete to be Grade C15/ Hydrant and Valve Indicator Plates Hydrant indicator plates and baseboards shall comply with B.S while sluice valve indicator plates and baseboards shall comply with the Dublin City Council Specification. They shall be mounted at the boundary of the public thoroughfare nearest to the hydrant or valve. Marker posts shall be concrete, comply with IS EN206-1 and be set 450mm deep in a concrete base. 5.8 Storage, Handling and use of Materials All pipes and fittings shall be stored off the ground in a clean environment to prevent any contamination of materials prior to use. All pipes shall be capped at either end until they are used in the Works to prevent vermin entering them and contaminating these materials before their use. All fittings supplied in sealed bags shall remain bagged until immediately prior to installation. Materials and components shall be handled in such a manner as to avoid any damage or contamination and in accordance with all applicable recommendations of the manufacturers. Pipes and fittings, including any lining or coating, shall be examined for damage before laying. Plastic pipes shall be carefully examined for flaws; particular watch shall be kept for 3

4 signs of impact damage and scoring. No polyethylene pipe shall be installed with scores or cuts penetrating more than 10% of the wall section. If, after installation, scores or cuts penetrating more than 10% of the wall section are found, the affected lengths of pipe shall be removed. 6. DEPTH AND POSITION OF PIPES All pipes shall have a minimum depth of cover of 750mm and maximum depth of 900mm measured from the top of the pipe to the finished ground surface. There shall be a minimum clear horizontal distance of 300mm between the distribution watermain and other utilities, cabinets, poles, junction boxes or chambers. No other service shall be laid over the line of the watermain. There shall be a minimum vertical clearance of 100mm where other services cross over the watermain. Pipes/ducts, cabinets, poles, junction boxes or chambers shall not be constructed on top of a watermain. 7. TRENCH WIDTH The trench should be kept as narrow as possible, but must allow adequate room for pipe jointing and placing and compaction of backfill, a width of 300mm greater than the outside diameter of the pipe being laid will normally be found adequate for these purposes. The trench width should normally not exceed the diameter by more than 500mm. A guideline for trench width is shown below. Diameter of main( mm) <80mm 100mm 150mm 200mm 250mm 300mm 350mm 400mm 450mm Trench Width (mm) 500mm 500mm 600mm 600mm 750mm 750mm 750mm 900mm 900mm Initial lines in bituminous or concrete roads and footpaths shall be cut using a concrete saw or equivalent mechanical means. 8. THRUST BLOCKS Appropriate thrust blocks shall be designed and installed on the main. Except where selfanchoring joints are used, thrusts from bends and branches in mains shall be resisted by concrete thrust blocks cast in contact with undisturbed ground. Concrete support blocks shall be cast to hydrant tees and sluice valves installed in plastic pipelines in order to resist the torque forces imposed on the fittings during operation. Support blocks shall be cast in such a manner so as not to interfere with the operation or maintenance of the apparatus. In general, support blocks should not cover any pipe or fitting joints. Plastics pipes shall be wrapped with a layer of plastic sheeting having a composition in accordance with BS 6076 before being surrounded by concrete (grade C28/35 to IS EN 206-1). Thrust blocks shall be allowed to develop adequate strength before any internal pressure is applied to the pipeline. 4

5 9. WARNING MESH All pipework shall have a 400mm wide water warning mesh, - Plyage HR 40D blue polyethylene warning mesh or similar laid directly over the centreline of the pipeline and tied to valves, at a depth of 350mm below the finished ground surface. Supply pipes shall have a mesh 200mm wide laid at the same depth. 10. PIPE JOINTS Pipe joints shall be one of the following types: Push-in rubber ring joint. Bolted flanged joints. Flexible couplings, e.g. Viking Johnson couplings with Rilsan coating, or similar approved types. Fusion welded joints. Site fusion jointing shall be carried out strictly in accordance with UK WIS using equipment to UK WIS All joints shall be made strictly in accordance with the manufacturer s instructions. 11. CLEANING PIPES All pipes shall be examined internally for dirt, stones, or any foreign matter and shall be thoroughly cleaned before laying in final position. To prevent foreign matter or vermin entering the main as it is being laid, all open ends of laid pipes shall be plugged until the next pipe is ready for insertion. 12. BEDDING MATERIAL All pipes shall be laid on a 150mm bed of rounded single sized pebble of 10mm nominal diameter and haunched and covered to a depth of 150mm with similar material. Pipes shall not be supported by stone or rock at any point. Rock shall be excavated to a depth of 150mm below the actual depth of trench required and backfilled with DOE Clause 805 prior to laying the pebble bed. In ground that contains ashes or chemicals or anything other than inert material, the material to be used and method of laying shall be agreed in writing with the City Council Water Division prior to laying. 13. BACKFILLING MATERIAL IN OR ADJACENT TO ROADWAYS All trenches in or near roadways shall be backfilled with DOE Clause 804, which shall be compacted to City Council requirements in layers not exceeding 225mm compacted by hand vibrators. Mechanical compactors should not be used until the total depth of backfill over the pipe exceeds 450mm. 14. LOCATION OF OTHER UTILITIES Any available records and proprietary cable locators shall be used prior to excavations taking place. Due diligence shall be used when making excavations for watermains and services and care shall be taken to protect and support all existing services (water, gas, telecommunications, drainage and electricity mains) and other works so as not to interfere with the working arrangement of same. 5

6 The Dublin City Council Water Services Division should be contacted before any work which is due to be carried out in the vicinity of an arterial watermain takes place. 15. NETWORK LAYOUT All mains must terminate in a ring or loop of sufficient size to accommodate at least one hydrant (See Dublin City Council Standard Details if necessary). Sluice valves shall always be inserted on branch lines and also as necessary to ensure that no more than 40 properties need be isolated at a time. The minimum size of watermain shall normally be 100mm nominal internal diameter but pipes with a nominal internal diameter of 80mm may be allowed in certain circumstances and only after prior written permission from the Water Services Division had been obtained. Watermains shall be located a minimum of 1m from the boundary of a premises. Watermains shall not be installed under buildings or in areas with either specialist finishes or trees / shrubs / flowers. Surface water attenuation tanks or barriers shall not be installed over watermains. No domestic property shall be more than 46m from a hydrant. Hydrants serving nondomestic properties shall be subject to the approval of the Dublin City Council Fire Officer. The location of hydrants should be such that they can be accessed in an emergency. Hydrants shall only be located in paths or open space or other approved areas. Where a watermain is located in a road, the hydrant shall be legged in to the nearest suitable path or open space. Such legged in hydrants shall include a separate valve on the tee piece off the main where the main is 300mm or greater. The connection to a development shall include the installation of the following at the boundary between the public and private sections of pipe: 1. A boundary box if the pipe is 32mm or less, 2. Two valves with a blank tee in between if the pipe is greater than 32mm and less than 100mm. A suitable chamber(s) plus cover and frame shall be installed. 3. A hydrant with a separate valve downstream of it if the pipe is 100mm or greater. A hydrant chamber plus cover and frame shall be installed. 16. ACCESS Developments shall have unrestricted access at all times. Accesses shall be at least 4m in height and 3m wide to facilitate public service vehicles. 17. TESTS After the pipes have been laid and jointed, the main shall pass the following tests: 18.1 Pressure Test Mains shall be subjected to 5 bar for 24 hours and shall be increased to 9 bar for 1 hour in the presence of a representative of the City Council. Testing shall be carried out between suitably supported blank end pieces. Testing between live shut valves will not be accepted. Polyethylene pipes shall be tested in accordance with the manufacturer s recommendations Chlorination Test All mains shall be swabbed and disinfected before being put in to supply. The pipelines shall be disinfected with water having a minimum concentration of 20mg/l of free available chlorine. This can be achieved using a sodium hypochlorite solution. Many hypochlorite solutions are available on the market, such as Chloros, Eirochlor, Chemchor, Sodium Hypochlorite etc. and 6

7 these contain % of available chlorine by weight. These may be purchased in any good chemical supply company. The recommended dosage of sodium hypochlorite solution is as follows: Main Diameter Vol. of sodium hypochlorite per 100m of main 10% 14% 100mm 150ml 110ml 150mm 350ml 250ml Other dosage figures can be extrapolated from these figures. The chlorinated water shall be left in the main for a period of at least 24 hours. Chlorine residual tests shall be taken at the end of the main furthest from the point of injection. The sterilisation process shall be repeated if the chlorine residual is less than 10mg/l. The chlorinated water shall be discharged into a foul sewer and never into a surface water sewer or watercourse and shall be subject to the prior approval of the DCC Water Pollution Engineer 18.3 Bacteriological Test The main shall then be refilled and a sample of the water shall be taken for bacteriological analysis. Great care shall be taken when obtaining samples for testing and only sterile containers shall be used. This sampling shall be carried out in the presence of the Engineer and/or his/her representative. Samples shall be tested within 6 hours of collection. Water samples may be tested in the following centre or in any approved or accredited laboratory. Public Analyst Laboratory, Sir Patricks Dun s Hospital, Lower Grand Canal Street, Dublin 2. Tel: Note: The Water Services Division will not connect the new main to the existing network until a copy of a satisfactory bacteriological test report has been submitted to the DCC Water Services Division for approval Internal Plumbing All internal plumbing in every development must comply with the Dublin City Council Water Services Division Plumbing Regulations, the Bye-Laws for the Management of Water Services and the Conservation of Drinking Water Arrangements must be made to have the internal plumbing inspected and approved by a representative from the Water Services Division Plumbing Inspectorate. All developments over two storeys must submit details of the pump and break tank arrangement to the Plumbing Inspectorate for approval. It is strongly suggested that Contractors consult with the Water Division Plumbing Inspectorate at an early stage so as to ensure that only approved materials/fittings are used. A water connection approval will not be issued until the internal plumbing has been approved As Constructed Drawings Accurate as constructed drawings shall be submitted to the Water Services Division as soon as possible. The drawings shall be in hard copy and in DXF (Drawing Exchange Format) CAD Format. The DXF shall be geographically referenced to OSI coordinates and all reference files shall be included on the CD. The different utilities shall be on different layers. 7

8 Confirmation shall be provided that delivery media has been scanned and is free of all known computer viruses. 18. CONNECTION TO CITY COUNCIL MAINS Connections to mains, which are the property of the Dublin City Council, may be made by the City Council only. No other person shall interfere in any way with these mains. 19. FLUSHING When mains have been satisfactorily tested and connected to the City Council main, they shall be flushed out with potable water through a standpipe placed on the end hydrant before the main is brought into use. 20. HEALTH AND SAFETY A Safety statement prepared in accordance with the Health Safety and Welfare at Work Act 2005 and subsequent regulations must be kept on site at all times. 21. EU DIRECTIVE ON MATERIALS, PIPES AND FITTINGS Nothing stated in this Specification is to be construed as discriminating against products and materials manufactured in any of the Member States of the European Community. Where items to an Irish Standard Specification, a British Standard Specification, or any other Standard Specification of a Member State of the European Community are called for, this requirement shall be read as including items to a relevant international standard, or the relevant national standard of any Member State of the European Community, which provides an equivalent guarantee of safety and suitability. Where items certified by the National Standards Authority of Ireland as complying with an Irish Standard are called for, the provisions of Circular Letter BM2/97 shall apply, i.e. the requirement shall be read as either certified by the National Standards Authority of Ireland as complying with the Irish Standard, or shall be certified as complying with a relevant international standard, or with the relevant national standard of another Member State of the European Community, which provides an equivalent guarantee of safety and suitability