Part-01 General

  • 1 GENERAL ...................................................................................................... 2
  • 1.1 INTRODUCTION ........................................................................................... 2
  • 1.1.1 Scope 2
  • 1.1.2 References 2
  • 1.2 REGULATIONS AND STANDARDS .............................................................. 2
  • 1.2.1 Public Works Authority 2
  • 1.3 CONTRACTOR’S RESPONSIBILITY ............................................................ 2
  • 1.3.1 General 2
  • 1.3.2 Existing Services 2
  • 1.3.3 Maintenance Period Requirements 2
  • 1.4 CRAFTSMEN ................................................................................................. 2
  • 1.4.1 Workmanship 2
  • 1.4.2 Qualifications 3
  • 1.5 MATERIALS ................................................................................................... 3
  • 1.5.1 General 3
  • 1.6 DRAWINGS ................................................................................................... 3
  • 1.6.1 Shop Drawings 3
  • 1.6.2 Co-ordination Drawings 3
  • 1.6.3 As-Built Record Drawings and Survey Drawings 3
  • 1.7 SITE WORKS ................................................................................................ 4
  • 1.7.1 Co-operation with other Trades 4

 


1 GENERAL

  • 1.1 INTRODUCTION
    • 1.1.1 Scope
      • 1 This Section specifies the requirements for the construction and installation of drainage works for buildings. It does not include highway drainage.
      • 2 Related Sections are as follows:
      • Section 1 General
      • 1.1.2 References
      • 1 The following standards are referred to in this Part:
      • BS 8000...................... Workmanship on building sites
  • 1.2 REGULATIONS AND STANDARDS
    • 1.2.1 Public Works Authority
      • 1 The Contractor shall carry out his work in accordance with the relevant requirements of the Public Works Authority.
  • 1.3 CONTRACTOR’S RESPONSIBILITY
    • 1.3.1 General
      • 1 The Contractor is responsible for obtaining all necessary approvals and permits required to complete the parts of the Works included in this Section.
    • 1.3.2 Existing Services
      • 1 The Contractor is responsible for locating and identifying all existing services that may affect, or be affected by, the construction of the parts of the Works included in this Section.
    • 1.3.3 Maintenance Period Requirements
      • 1 The Contractor is responsible for all the maintenance period requirements for all parts and components of the Works included in this Section.
  • 1.4 CRAFTSMEN
    • 1.4.1 Workmanship
      • 1 Workmanship shall comply with the relevant provisions of BS 8000.
      • 2 Construction of each part of the Works covered in this Section shall be undertaken by experienced craftsmen capable of performing the tasks allocated to them in a professional and competent manner.
      • 3 If required by the Engineer, the Contractor shall instruct craftsmen to demonstrate their ability to perform tasks allocated to him.
    • 1.4.2 Qualifications
      • 1 Where the Project Documentation specifies that specialist craftsmen are required to undertake a specific work task, the Contractor shall furnish the Engineer with copies of qualifications pertinent to performing such work tasks for those craftsmen who will be undertaking the work.
  • 1.5 MATERIALS
    • 1.5.1 General
      • 1 All materials, components and products shall comply with the relevant provisions of Section 1, General.
      • 2 All materials, components and products shall be supplied by experienced manufacturers as designated in the Project Documentation or to the written approval of the Engineer.
  • 1.6 DRAWINGS
    • 1.6.1 Shop Drawings
      • 1 The Contractor shall prepare shop drawings for all parts of the Works to be installed or constructed under this Section and submit them to the Engineer in accordance with the relevant provisions of Section 1, General. The shop drawings shall include diagrams, illustrations, schedules, general arrangements of equipment and appurtenances in relation to buildings and structures, method statements and details of specialised installation and construction work.
    • 1.6.2 Co-ordination Drawings
      • 1 These shall be prepared by the Contractor to show how interdisciplinary work will be co-ordinated. The location, size and details of fixings, box-outs, ducts, holes, pipe chases and plinths shall be shown on the detailed layout drawings which shall be fully co-ordinated with all other work disciplines.
    • 1.6.3 As-Built Record Drawings and Survey Drawings
      • 1 The Contractor shall prepare Record Drawings of all works constructed or installed under this Section in accordance with the relevant provisions of Section 1, General. These shall be prepared as work proceeds. They shall provide a record of any modification to materials and equipment, and to the layout, arrangement and installation of the Works.
  • 1.7 SITE WORKS
    • 1.7.1 Co-operation with other Trades
      • 1 The Contractor shall so organise work progress to harmonise with the work of all trades so that work may proceed as expeditiously as possible. The Contractor shall be responsible for the correct placing of the Works and the connection thereof to the work of all related trades.

 

END OF PART

 

Part-03 External Drainage Works

  • 3 EXTERNAL DRAINAGE WORKS .................................................................. 2
    • 3.1 GENERAL ...................................................................................................... 2
      • 3.1.1 Scope 2
      • 3.1.2 References 2
      • 3.1.3 System Description 2
    • 3.2 PIPEWORK .................................................................................................... 3
      • 3.2.1 General 3
      • 3.2.2 Vitrified Clay Pipework 3
      • 3.2.3 Unplasticized Polyvinyl Chloride (PVC-U) Pipework 3
      • 3.2.4 Testing of Pipework 3
    • 3.3 ACCESSORIES ............................................................................................. 3
      • 3.3.1 Gullies and Gully Gratings 3
    • 3.4 CONNECTION TO EXISTING PIPELINES .................................................... 4
      • 3.4.1 Connections to Existing Government Mains 4

 


3 EXTERNAL DRAINAGE WORKS

  • 3.1 GENERAL
    • 3.1.1 Scope
      • 1 This Part specifies the requirements for pipework and accessories for external drainage works in building areas. External drainage works includes foul water sewerage and surface water sewerage.
      • 2 Related Sections and Parts are as follows:
        • This Section
        • Part 1 General
        • Part 6 Commissioning of Systems
        • Section 1 General
        • Section 5 Concrete
        • Section 6 Roadworks
        • Section 8 Sewerage
    • 3.1.2 References
      • 1 The following standards are referred to in this Part:
        • BS 2494 ...................... Elastomeric seals for joints in pipework and pipeline
        • BS 4346 ..................... Joints and fittings for use with unplasticized PVC pressure pipes.
        • BS 4660 ...................... unplasticized polyvinyl chloride (PVC-U) pipes and plastic fittings of nominal sizes 110 and 160 for below ground drainage and sewage
        • BS 5481 ...................... Unplasticized PVC pipe and fittings for gravity sewers
        • BS 6209 ..................... Solvent cement for non-pressure thermoplastic pipe systems
        • BS EN 295 ................. Vitrified clay pipes and fittings and pipe joints for drains and sewers
        • ISO 4633 .................... Rubber Seals -Joints rings for supply, drainage
    • 3.1.3 System Description
      • 1 Pipes and fittings to be used for foul sewerage shall be suitable for carrying sewage at temperatures of up to 45.C with hydrogen sulphide concentrations up to 400 mg/l.
      • 2 Pipes shall be suitable for immersion in corrosive groundwater conditions typically exhibiting the following characteristics unless otherwise specified:
        • SO3 Content : 1.7 g/l
        • CI Content : 1.07 g/l
        • pH : 8.6
        • Conductivity : 4000 .s/cm
      • 3 The Contractor shall be responsible for providing a jointing system as recommended by the pipe manufacturer that enables the installation and use of the designated pipeline systems.
  • 3.2 PIPEWORK
    • 3.2.1 General
      • 1 Pipes shall have adequate strength to meet the loading requirements, be sufficiently robust to withstand site handling and be sufficiently durable to remain watertight for the anticipated life of the system.
      • 2 Pipes and joints should remain sufficiently water tight to prevent the ingress of ground water and the ingress of effluent when subject to ground movement and settlement.
    • 3.2.2 Vitrified Clay Pipework
      • 1 Vitrified clay pipes and fittings for drains and sewers shall comply with the relevant provisions of BS EN 295.
      • 2 Pipes shall have spigot and socket joints complying with the relevant provisions of BS EN 295. Joints shall have elastomeric joint seals. Complying with the relevant provision of ISO 4633 or, BS 2494 (Type D) and shall be obtained from the pipe manufacturer. For pipes up to 150 mm diameter, push-fit (sleeve type) polypropylene flexible couplings may be used in place of spigot and socket joints.
      • 3 All other requirements related to the manufacture, inspection and testing of vitrified clay pipes shall be in accordance with the relevant provision of Section 8, Sewerage.
    • 3.2.3 Unplasticized Polyvinyl Chloride (PVC-U) Pipework
      • 1 PVC-U pipe joints and fittings for gravity drains and sewers shall comply with the relevant provisions of BS 4660 or 5481.
      • 2 Joints shall have elastomeric joint seals complying with the relevant provisions of ISO 4633 or BS 2949 (Type D) and shall be obtained from the pipe manufacturer.
      • 3 Solvent cements for jointing PVC-U pipes shall comply with BS 4346. For pipes and fittings complying with BS 4660, solvent cement may alternatively comply with BS 6209.
      • 4 All other requirements related to the manufacture, inspection and testing of PVC-U pipes shall be in accordance with the relevant provisions of Section 8, Sewerage.
    • 3.2.4 Testing of Pipework
      • 1 Internal and external pressure tests shall be carried out on external drainage pipes. Test procedures are detailed in Part 6 of this Section.
  • 3.3 ACCESSORIES
    • 3.3.1 Gullies and Gully Gratings
      • 1 Gullies and gully gratings shall comply with the relevant provisions of Section 6, Roadworks.
  • 3.4 CONNECTION TO EXISTING PIPELINES
    • 3.4.1 Connections to Existing Government Mains
      • 1 Connections to existing Government mains shall comply with the relevant provisions of Section 8, Sewerage, and the following clauses.
      • 2 Where possible and practicable, connections shall be made to future connection ports in existing Government manholes. The caps on future connection ports to which connections are made shall be cleaned and delivered to the government stores in accordance with he relevant provisions of Section 1, General.
      • 3 Where it is not possible of practicable to utilise future connection ports in existing manholes, connections shall be made by either breaking into existing manholes or constructing new manholes on existing mains.
      • 4 If it is necessary to break into an existing manhole, the Contractor shall break into the manhole wall, insert pipework, break out the existing benching, construct benching to suit new connection and make good. If necessary, the Contractor shall relocate the access ladder and the cover slab to suit the new benching layout.
      • 5 Manholes built on an existing Government mains shall be constructed in accordance with Clause 6 of this Part. On completion, such manholes shall become the property of the government.
      • 6 The Contractor shall be responsible for all over-pumping operations associated with making connections to Government mains.

 

END OF PART

 

Part-05- Structures Relates to Drainage Work

  • 5 STRUCTURES RELATED TO DRAINAGE WORK ....................................... 2
    • 5.1 GENERAL ...................................................................................................... 2
      • 5.1.1 Scope 2
      • 5.1.2 References 2
      • 5.1.3 Concrete Work 2
      • 5.1.4 Pipes built into structures 2
    • 5.2 CONSTRUCTION OF MANHOLES, CHAMBERS AND SOAKAWAYS ........ 2
      • 5.2.1 General 2
      • 5.2.2 Soakaways 2
    • 5.3 PRECAST CONCRETE MANHOLES ............................................................ 3
      • 5.3.1 General 3
      • 5.3.2 Jointing of Precast Manholes 3
    • 5.4 TESTING OF STRUCTURES RELATED TO DRAINAGE WORK ................. 3
      • 5.4.1 General 3

 


5 STRUCTURES RELATED TO DRAINAGE WORK

  • 5.1 GENERAL
    • 5.1.1 Scope
      • 1 This Part specifies the requirements for the construction of manholes, chambers and soakaways for drainage works.
      • 2 Related Section and Parts are as follows:
        • This Section
        • Part 1 General
        • Part 3 External Drainage Works
        • Part 6 Commissioning of Systems
        • Section 5 Concrete
        • Section 6 Roadworks
        • Section 8 Sewerage
    • 5.1.2 References
      • 1 The following standards are referred to in this Part:
      • PWA Developer’s Drainage Guide
    • 5.1.3 Concrete Work
      • 1 Concrete for manholes, chambers and soakaways shall comply with the relevant provisions of Section 5, Concrete.
    • 5.1.4 Pipes built into structures
      • 1 Where pipes are built into concrete, they shall be rigidly secured in position to prevent movement and shall be free from external coatings which might adversely affect the bond.
  • 5.2 CONSTRUCTION OF MANHOLES, CHAMBERS AND SOAKAWAYS
    • 5.2.1 General
      • 1 The construction of manholes and chambers for drainage works for foul sewage and surface water sewage shall comply with the relevant provisions of the following:
        • (a) Section 8 of this Specification, Sewerage
        • (b) PWA - Developer’s Drainage Guide
    • 5.2.2 Soakaways
      • 1 Soakaways for surface water sewage shall comply with the relevant provisions of Section 6, Roadworks, except as amended in this Part.
      • 2 Soakaways shall not be constructed closer than 5 m from a building or in a position where the ground below foundations is likely to be affected.
      • 3 Precast concrete soakaways shall be dry jointed.
  • 5.3 PRECAST CONCRETE MANHOLES
    • 5.3.1 General
      • 1 Precast concrete manholes shall comply with the relevant provisions of the PWA, except as amended in this Part.
    • 5.3.2 Jointing of Precast Manholes
      • 1 The jointing material for precast manholes shall be mortar or a proprietary bitumen or resin mastic sealant, with the concrete surfaces primed with an appropriate sealant. The jointing material which is extruded inside the manhole shall be trimmed off and joints pointed on completion.
      • 2 Units which bed onto bases shall be manufactured so that imposed vertical loads are transmitted directly via the full wall thickness of the unit.
      • 3 For joints between units and the underside of slabs, joint profiles shall be capable of withstanding applied loadings from such slabs. Spigot ended sections shall only be used where the soffit of the slab is recessed to receive them.
  • 5.4 TESTING OF STRUCTURES RELATED TO DRAINAGE WORK
    • 5.4.1 General
      • 1 Testing of structures related to drainage work shall be done in accordance with the relevant provisions of Part 6 of this Section.

 

END OF PART

 

Part-02 Internal Drainage Works

  • 2 INTERNAL DRAINAGE WORKS ................................................................... 2
    • 2.1 GENERAL ...................................................................................................... 2
      • 2.1.1 Scope 2
      • 2.1.2 Reference 2
      • 2.1.3 Contractor’s Responsibility 3
      • 2.1.4 System Description 3
      • 2.1.5 Site Work 3
      • 2.1.6 Fixing 3
      • 2.1.7 Sealants 3
      • 2.1.8 Inspection 4
    • 2.2 INTERNAL DRAINAGE PIPEWORK ............................................................. 4
      • 2.2.1 General 4
      • 2.2.2 Materials 4
    • 2.3 LABORATORY DRAINAGE SYSTEMS ......................................................... 4
      • 2.3.1 General 4
    • 2.4 GULLIES ........................................................................................................ 5
      • 2.4.1 Floor Gullies 5
    • 2.5 ACCESS TO DRAINS .................................................................................... 5
      • 2.5.1 General 5
    • 2.6 ROOF TERMINATION ................................................................................... 5
      • 2.6.1 Ventilating Pipes and Stack Vents 5
    • 2.7 PUMPING FACILITIES .................................................................................. 6
      • 2.7.1 Sump Pumps 6
    • 2.8 SANITARYWARE INSTALLATIONS ............................................................. 6
      • 2.8.1 General 6
      • 2.8.2 Pedestal WC Pans 6
      • 2.8.3 Squat Type Toilet 6
      • 2.8.4 Flushing Cisterns for Toilets 6
      • 2.8.5 Slab Urinals 7
      • 2.8.6 Bowl Urinals 7
      • 2.8.7 Wash-basins 7
      • 2.8.8 Sinks 7
      • 2.8.9 Showers 8
      • 2.8.10 Taps 8
      • 2.8.11 Traps 8

 


2 INTERNAL DRAINAGE WORKS

  • 2.1 GENERAL
    • 2.1.1 Scope
      • 1 This Part specifies the requirements for internal drainage pipework, internal drainage systems and sanitary appliances.
      • 2 Related Sections and Parts are as follows:
        • This Section
        • Part 1 General
        • Part 7 Commissioning of Systems
        • Section 1 General
        • Section 8 Sewerage
        • Section 9 Mechanical and Electrical
    • 2.1.2 Reference
      • 1 The following standards are referred to in this Part:
        • BS 416 ........................ Discharge and ventilating pipes and fittings, sand-cast or spun in cast iron
        • BS 437 ........................ Specification for cast iron spigot and socket drain pipes and fittings
        • BS 539 ........................ Dimensions of fittings for use with clay drains and sewer pipes
        • BS 1010...................... Specification for draw-off taps and stopvalves for water services (screw-down patterns)
        • BS 1125...................... WC flushing cisterns
        • BS 1184...................... Specification copper and copper alloy traps
        • BS 1188...................... Ceramic wash basins and pedestals
        • BS 1206...................... Fireclay sinks. Dimensions and workmanship
        • BS 1212...................... Float operated valves
        • BS 1244...................... Metal sinks for domestic purposes
        • BS 1254...................... Specification for WC seats (plastics)
        • BS 1255...................... WC seats (plastics)
        • BS 2456...................... Specification for floats (plastics) for ballvalves for hot and cold water
        • BS 3402...................... Quality of vitreous china sanitary appliances
        • BS 4514...................... Unplasticized PVC soil and ventilation pipes, fittings and accessories
        • BS 5254...................... Polypropylene waste pipe and fittings (external diameter 34.6 mm, 41.0 mm and 54.1 mm)
        • BS 5255...................... Thermoplastics waste pipe and fittings
        • BS 5503...................... Specification for vitreous china washdown WC pans with horizontal outlet
        • BS 5572...................... Sanitary Pipework
        • BS 5889...................... One-part gun grade silicone-based sealants
        • BS 8313...................... Code of Practice for accommodation of building services in ducts
    • 2.1.3 Contractor’s Responsibility
      • 1 The Contractor is responsible for checking the dimensions of all internal drainage works to be installed against the availability of space at their intended installation location.
    • 2.1.4 System Description
      • 1 Internal drainage systems shall generally conform to the relevant provisions of BS 5572.
      • 2 Internal drainage systems shall comprise the minimum pipework necessary to carry away the discharges from sanitary appliances in buildings quickly and quietly.
      • 3 Drainage pipework installations shall be such that there is no leakage of contaminated water or foul air into the building.
      • 4 Drainage systems, including materials, joints, supports and fixings shall be durable under the expected operating conditions.
      • 5 Pipework and fittings in drainage systems shall be installed so that defective parts can be replaced without undue difficulty.
    • 2.1.5 Site Work
      • 1 A check should be made to ensure that all holes, chases and ducts required for pipework have been properly provided in accordance with the relevant provisions of BS 8313.
      • 2 Where several pipes pass through floors in close proximity, the Contractor may provide a single framed opening in lieu of individual sleeves. Framed openings shall be to the approval of the Engineer and shall be provided with 100 mm high curbs, on all sides.
    • 2.1.6 Fixing
      • 1 Water supply and discharge pipes should be installed before sanitary appliances are fixed. Before fixing an appliance into position, the Contractor shall ensure that the discharge pipe is clear of obstruction. Joints between appliances and traps and/or pipes should be of the union or detachable type.
      • 2 Sinks and baths should be installed so that they drain to the outlet by gravity.
      • 3 Cistern overflow pipes should be arranged to give a visible warning of discharge.
    • 2.1.7 Sealants
      • 1 Sealants shall comply with the relevant provisions of BS 5889, type B (high modulus sealant) with a fungicide incorporated. The sealant should be applied using a purpose made gun or devise.
    • 2.1.8 Inspection
      • 1 Upon completion of the work, all appliances, materials and workmanship should be carefully examined for defects and for faults in installation. Any defects or faults shall be corrected before the appliances are handed over for use.
  • 2.2 INTERNAL DRAINAGE PIPEWORK
    • 2.2.1 General
      • 1 Pipes and fittings used shall be suitable for their purpose.
      • 2 If pipes, pipe joints and pipe fittings are of dissimilar metals, measures shall be taken to prevent electrolytic corrosion.
      • 3 The Contractor shall comply with all the recommendations of manufacturers when jointing pipes of different materials.
    • 2.2.2 Materials
      • 1 Soil, waste and ventilating pipes, fittings and accessories for above ground drainage systems shall comply with the relevant provisions of the appropriate standard, as set out in Table 2.1.
  • Table 2.1
    Standards for pipes, fittings and accessories for above ground drainage systems
MaterialStandard
Cast Iron BS 416, Parts 1 and 2
PVC-U (soil and ventilating) BS 4514
Polypropylene (waste) BS 5254
Plastic (waste) BS 5255
      • 2 Internal drainage pipes and fittings for below ground applications shall comply with the relevant provisions of Section 8, Sewerage.
  • 2.3 LABORATORY DRAINAGE SYSTEMS
    • 2.3.1 General
      • 1 The chemical resistance properties of pipes, fittings, jointing systems and any other drainage accessory shall be suitable for conveying all solutions expected to be discharged to the drainage system. Where possible, technical advisory services provided by manufacturers shall be used to ascertain the suitability of products to be used in the drainage system. A full list of the solutions expected to be discharged to the drainage system is given in the Project Documentation.
      • 2 Drainage systems for the collection of solutions which are not permitted to be discharged to existing drainage facilities shall be kept totally separate form other drainage systems.
      • 3 Drainage systems to which grit, gravel, sand or other granular material shall be discharged shall have sufficient abrasion resistance properties and be fitted with suitable traps and catch basins.
  • 2.4 GULLIES
    • 2.4.1 Floor Gullies
      • 1 Floor gullies shall comply with the requirements of the following paragraphs unless otherwise detailed in the Project Documentation.
      • 2 Floor gullies shall be coated cast iron and comply with the relevant provisions of BS 539. They shall have a 90 mm diameter trapped outlet and be fitted with a galvanised flat grating of an approved type.
      • 3 Floor drains shall be selected with sufficient grate free area to pass the anticipated flow. The grate free area is defined as the total area of the drainage openings in the grate and shall be not less than 1.5 times greater than the pipe to which the grate is draining.
      • 4 With the exception of those located in toilets, all floor drains fitted with traps shall incorporate a removable bucket.
      • 5 The gully should be installed on a firm base and located relative to the floor finish. The method of fixing shall be as detailed in the Project Documentation.
  • 2.5 ACCESS TO DRAINS
    • 2.5.1 General
      • 1 Sufficient and suitable access should be provided to enable all pipework to be tested and maintained effectively. Access covers, plugs or caps should be sited so as to facilitate the insertion of testing apparatus and the use of equipment for cleaning and/or for the removal of blockages. The use of apparatus or equipment should not be impeded by the structure or other services.
      • 2 Access points should not be located where their use may give rise to nuisance or danger if spillage occurs.
  • 2.6 ROOF TERMINATION
    • 2.6.1 Ventilating Pipes and Stack Vents
      • 1 Ventilating pipes and stack vents shall terminate with a domical cage or other cover that does not restrict air flow. They shall be positioned so that foul air does not cause a nuisance or health hazard.
  • 2.7 PUMPING FACILITIES
    • 2.7.1 Sump Pumps
      • 1 Sump pumps shall comply with the relevant provisions of Section 9, Mechanical and Electrical Equipment.
  • 2.8 SANITARYWARE INSTALLATIONS
    • 2.8.1 General
      • 1 Sanitary fittings shall, unless otherwise stated in the Project Documentation, be as described in the following Clauses.
      • 2 Where screws are used to fix sanitary appliances to concrete, blockwork or brickwork they shall be rust-proofed steel and plugged.
    • 2.8.2 Pedestal WC Pans
      • 1 Pedestal WC pans shall be of white glazed fireclay and shall comply with the relevant provisions of BS 5503. They shall have P, Q or S traps as required. WC seats shall be black plastic and shall comply with the relevant provisions of BS 1254. The traps shall be provided with antisyphonage outlets, where required
      • 2 Where pans are fixed to timber floors they shall be jointed to the drain pipe with hemp gaskin and red lead putty. Where pans are fixed to concrete floors, they shall be jointed to the drain pipe with cement/sand mortar mixed in a 1:2 ratio. The pans shall be screwed to the floor.
    • 2.8.3 Squat Type Toilet
      • 1 Squat type toilets shall comprise a closet of white vitreous china complying with the relevant provisions of BS 3402 for sinking into the floors and integral or separate tread plates in a matching material. They shall have P, Q or S trap as required. The traps shall be provided with antisyphonage outlets, where required.
      • 2 The closets and tread plates shall be set into a concrete bed with the top surface level with the floor finish.
    • 2.8.4 Flushing Cisterns for Toilets
      • 1 Flushing cisterns shall be black plastic or white vitreous china complying with the relevant provisions of BS 1125 and shall be the single flushing type. They shall be fitted with a nylon or brass ball valve complying with the relevant provisions of BS 1212 with a plastic float complying with the relevant provisions of BS 2456. They shall have connections for 12 mm diameter supply and 20 mm diameter overflow pipes. Flush pipes complying with the relevant provisions of BS 1125 shall be provided and shall be of galvanised mild steel.
      • 2 Flush pipes shall be jointed to the bottom of the cisterns by means of watertight unions which allow for easy removal and shall be jointed to WC pans by means of approved rubber cone connectors. The cisterns shall be fixed to walls with screws.
      • 3 High level cisterns shall be provided with chromium plated chains with rubber pull handles. They shall be fixed a height of 1500 mm from finished floor level to the underside of the cistern. Flush pipes shall be 30 mm diameter and shall be fixed with pipe clips which shall be screwed to walls.
      • 4 Low level cisterns shall be provided with chromium plated lever flushing handles. They shall be fixed at a height of 600 mm from finished floor level to the underside of the cistern. Flush pipes shall be 35 mm diameter.
    • 2.8.5 Slab Urinals
      • 1 Urinal slabs shall be white glazed fireclay and shall have end screens. All urinals shall have a white glazed fireclay floor channel and white glazed fireclay fluted treads set flush with the floor finish. The channel shall have a 40 mm diameter chromium plated brass outlet with hinged grating.
      • 2 The urinal slabs, channel and floor treads shall be bedded in cement mortar and jointed and painted with white cement. The flushing cistern shall be a white glazed fireclay automatic flushing cistern, complete with cover, and shall be fixed on white porcelain enamelled cast iron brackets which shall be screwed to the wall.
      • 3 Flush pipes and spreaders shall be chromium plated and shall be fixed to walls with chromium plated holderbats. A 40 mm diameter trap with 40 mm or 75 mm deep seal as necessary shall be provided.
    • 2.8.6 Bowl Urinals
      • 1 Urinals bowls shall be white glazed fireclay with lipped basin and flushing rim. Urinal bowls shall be screwed to the wall. Flushing cisterns, flushing pipes and spreaders shall be as described for slab urinals. The bowl urinals shall be complete with chromium plated brass outlet and trap.
    • 2.8.7 Wash-basins
      • 1 Wash-basins shall be white glazed fireclay size 625 mm x 450 mm overall and shall comply with the relevant provisions of BS 1188. Each basin shall be provided with a 30 mm diameter chromium plated waste outlet and rubber plug with a chromium plated chain and stay.
      • 2 A 30 mm diameter trap shall be fixed to each basin having a 40 mm deep seal and one or two 12 mm pillar taps shall be fixed as required. Where only one tap only is required, the basin shall be provided with a tap hole stopper to match the basin. Unless otherwise specified, each wash-basin shall be fixed on two cast iron brackets complying with the relevant provisions of BS 1255 which shall be screwed to the wall. If required the pedestal WC pan shall match the basin.
    • 2.8.8 Sinks
      • 1 Ceramic sinks shall be white glazed fireclay size 600 mm x 450 mm x 250 mm deep and shall comply with the relevant provisions of BS 1206.
      • 2 Metal sinks shall be stainless steel or aluminium to the sizes stated in the Project Documentation and shall comply with the relevant provisions of BS 1244.
      • 3 Each sink shall be provided with a 40 mm chromium plated brass waste outlet, outlet grating, overflow and rubber plug with chromium plated chain and stay. A 40 mm diameter trap shall be fixed to each sink having a 40 mm or 75 mm deep seal as necessary. Each sink shall have one or two 12 mm diameter pillar or bib taps, as required. Where only one tap is required, a tap hole stopper to match the sink shall be provided. Pillar taps shall have 150 mm raising pieces and bib taps shall have extension pieces of adequate length.
      • 4 Sinks shall be supported and fixed on brackets or legs unless otherwise specified in the Project Documentation. Two cast iron brackets shall be used for sinks supported and fixed on brackets. The brackets shall comply with the relevant provisions of BS 1255 and shall be screwed to the wall. Legs for supporting sinks shall be of cast iron or galvanised steel with a painted finish. Sinks shall be fixed at a height of 550 mm from the outlet grating to finished floor level.
    • 2.8.9 Showers
      • 1 Shower fittings shall comprise a 100 mm diameter adjustable chromium plated brass inclined shower head with rose and 12 mm diameter supply pipe(s) with 12 mm diameter stop valve(s) to control the water supply.
      • 2 The shower head shall be fixed a height of 1800 mm above the finished floor level. All exposed pipework and fittings serving the showers within the shower area shall be chromium plated and fixed with chromium plated holderbats.
    • 2.8.10 Taps
      • 1 All taps shall comply with the relevant provisions of BS 1010. Taps shall be of the following type as appropriate and, where necessary, shall be provided with extension pieces.
        • (a) pillar taps shall be 12 mm diameter chromium plated brass with cross heads.
        • (b) bib taps, unless otherwise stated, shall be 12 mm diameter chromium plated brass with cross heads, complete with backplate elbow or wall flange. Bib taps to stand pipes shall be 12 mm diameter unplated brass, and shall have an extended nozzle suitable for hose connections.
    • 2.8.11 Traps
      • 1 Traps shall be of the following types:-
        • (a) traps for sinks, lavatory basins and baths shall be copper, brass, or aluminium complying with the relevant provisions of BS 1184, complete with cleaning eye. Traps to sinks, baths shall have an overflow connection.
        • (b) traps for urinals with suspended drains shall be 75 mm diameter cast iron complying with the relevant provisions of BS 416, Table 14. They shall be fitted with cast iron connectors and threaded to receive the outlet from the urinal.
        • (c) traps for urinals with buried drainage shall be 75 mm diameter cast iron complying with the relevant provisions of BS 437. They shall be fitted with cast iron connectors and threaded to receive the outlet from the urinal.

 

END OF PART

 

Part-06 Surface Water Drainage

  • 6 SURFACE WATER DRAINAGE .................................................................... 2
    • 6.1 GENERAL ...................................................................................................... 2
      • 6.1.1 Scope 2
      • 6.1.2 References 2
      • 6.1.3 Submittals 3
      • 6.1.4 Pipe Marking 4
      • 6.1.5 Handling and Storage 4
      • 6.1.6 Quality Assurance 4
    • 6.2 PIPEWORK .................................................................................................... 4
      • 6.2.1 General 4
      • 6.2.2 Vitrified Clay Pipework 4
      • 6.2.3 Unplasticized Polyvinyl Chloride (PVC-U) Pipework 5
      • 6.2.4 Reinforced Concrete Pipes 5
      • 6.2.5 Testing of Pipework 5
    • 6.3 PIPE LAYING ................................................................................................. 5
      • 6.3.1 General 5
      • 6.1.1 Pipe Bedding 6
      • 6.3.2 Concrete Protection to Pipes 6
      • 6.3.3 Completion of Pipe Surround 6
      • 6.3.4 Backfilling 6
    • 6.4 GULLIES AND DRAINAGE CHANNELS ....................................................... 7
      • 6.4.1 Gullies 7
      • 6.4.2 Pre-formed Gullies 7
      • 6.4.3 Drainage Channels 8
    • 6.5 SOAKAWAYS ................................................................................................ 8
      • 6.5.1 General Requirements 8
    • 6.6 MANHOLES AND CATCH PITS .................................................................... 8
      • 6.6.1 General Requirements 8
    • 6.7 CONNECTION TO GOVERNMENT MAIN .................................................... 9
      • 6.7.1 General Requirements 9

 

6 SURFACE WATER DRAINAGE

  • 6.1 GENERAL
    • 6.1.1 Scope
      • 1 This Part specifies the requirement for pipework, gullies, manholes, catch pits, soakaways and other items related to surface water drainage.
      • 2 Related Sections and Parts are as follows:
        • This Section
        • Part 1 General
        • Part 6 Commissioning of Systems
        • Section 5 Concrete
    • 6.1.2 References
      • The following standards are referred to in this Part:
        • BS 65 .......................... Vitrified clay pipes, fittings and ducts, also flexible mechanical joints for use solely with surface water pipes and fittings
        • BS 497 ........................ Manhole covers, road gully grating and frames for drainage purposes
        • BS 743 ........................ Materials for damp-proof courses
        • BS 1142...................... Fibre building boards
        • BS 1247...................... Manhole steps
        • BS 2494...................... Elastomeric seals for joints in pipework and pipelines
        • BS 4660...................... unplasticized polyvinyl chloride (PVC-U) pipes and plastic fittings of nominal sizes 110 and 160 for below ground gravity drainage and sewerage
        • BS 6076...................... Tubular polythene film for use as protective sleeving for buried iron
          .................................. pipes and fittings
        • BS 5481...................... unplasticized PVC pipe and fittings for gravity sewers
        • BS 5911...................... Precast concrete pipes, fittings and ancillary products

          BS EN 124 ................. Gully tops and manhole tops for vehicular and pedestrian areas
        • BS EN 295 ................. Vitrified clay pipes and fittings and pipe joints for drains and sewers.
    • 6.1.3 Submittals
      • 1 The Contractor shall order materials to suit the construction programme and obtain the Engineer’s approval of submittals before placing orders. The Contractor shall submit two copies of the following documents for the approval of the Engineer.
        • (a) Product Data
          • (i) originals of catalogues and engineering data sheets for manufactured items; each item and option to be provided shall be clearly marked and each item not to be provided shall be deleted
          • (ii) literature to show that products provided meet the requirements for material, construction, operation, and testing
          • (iii) information on the following items as a minimum: pipes; pipe jointing systems, manhole covers and frames and gully covers, gratings and frames.
          • (iv) manufacturer’s installation instructions for all items
          • (v) certified reports for all tests and inspections designated herein, signed and sealed, showing full compliance with referenced standards
          • (vi) maintenance requirements and procedures
          • (vii) period of guarantee for products.
        • (b) Shop Drawings showing the following:
          • (i) profiles of each pipe system including chainage, ground levels, invert levels, critical clearances and position of pipework structures.
          • (ii) material, class, grade, joint type, pressure rating, dimension, location and identification number of each pipe and pipe fitting to be furnished and installed.
          • (iii) procedures for building pipes into concrete structures.
          • (iv) procedures for encasing pipes in concrete.
          • (v) class, dimensions, location and identification of each manhole cover and frame to be furnished and installed.
          • (vi) procedures for placing and fixing manhole covers and frames.
          • (vii) class, dimensions, location and identification of each gully cover, grating and frame to be furnished and installed.
          • (viii) procedures for placing and fixing gully covers, gratings and frames.
          • (ix) details for handling and storage of pipes, manhole covers and frames and gully covers, gratings and frames.
          • (x) all other miscellaneous details required for complete installation.
    • 6.1.4 Pipe Marking
      • 1 Each pipe and pipe fitting shall be marked with the following:
        • (a) serial number
        • (b) class of pipe
        • (c) nominal diameter
        • (d) name or trademark for manufacturer
        • (e) date of manufacture.
    • 6.1.5 Handling and Storage
      • 1 Each item to be provided under this Part shall be stored and handled in accordance with the recommendations of the manufacturer of the item.
      • 2 Products susceptible to ultra violet degradation shall be stored under cover and out of direct sunlight.
      • 3 Pipes and fittings shall be subject to visual inspections after off-loading at the site and before installation.
    • 6.1.6 Quality Assurance
      • 1 Pipes, pipe fittings, manhole covers and frames and gully covers, gratings and frames shall be supplied by approved manufacturers as designated in the Project Specification. Production facilities shall be quality assessed in accordance with ISO 9000 or equivalent.
  • 6.2 PIPEWORK
    • 6.2.1 General
      • 1 Pipes shall have adequate strength to meet the loading requirements, be sufficiently robust to withstand site handling and be sufficiently durable to remain watertight for the anticipated life of the system. Pipes and joints should remain sufficiently water tight to prevent the ingress of ground water.
    • 6.2.2 Vitrified Clay Pipework
      • 1 Vitrified clay pipes and fittings for surface water drainage shall comply with the relevant provisions of BS EN 295.
      • 2 Pipes and pipe fittings shall be extra strength class.
      • 3 All pipes and pipe fittings shall have flexible mechanical joints. Pipes with diameters larger than 150 mm shall have spigot and socket joints complying with the relevant provisions of BS EN 295. Spigot and socket joints shall have elastomeric joint seals, Type D, complying with the relevant provisions of BS 2494, and shall be obtained from the pipe manufacturer. Push-fit (sleeve type) polypropylene flexible couplings may be used in place of spigot and socket joints for pipes up to 150 mm diameter.
    • 6.2.3 Unplasticized Polyvinyl Chloride (PVC-U) Pipework
      • 1 PVC-U pipes and fittings for surface water drainage shall comply with the relevant provisions of BS 4660 and BS 5481.
      • 2 All pipes and pipe fittings shall have spigot and socket joints complying with the relevant provisions of BS 4660 and BS 5481. Spigot and socket joints shall incorporate Type D elastomeric joint seals complying with the relevant provisions for BS 2494 and shall be obtained from the pipe manufacturer.
    • 6.2.4 Reinforced Concrete Pipes
      • 1 Reinforced concrete pipes and fittings and flexible or ogee joints shall comply with the relevant provisions of BS 5911: Parts 100 and 110 respectively.
      • 2 All pipes and fittings shall have gasket type joints of spigot and socket or rebated form, unless otherwise described in the Project Specification or shown on the Project Drawings.
    • 6.2.5 Testing of Pipework
      • 1 Pressure tests shall be carried out on surface water drainage pipes. Test procedures are detailed in Part 6 of this Section.
  • 6.3 PIPE LAYING
    • 6.3.1 General
      • 1 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 made.
      • 2 Pipes shall be laid on setting blocks only where a concrete bed or cradle is used.
      • 3 Where pipes are required to be bedded directly on the trench bottom, the final excavated surface shall be trimmed and levelled to provide even bedding of the pipeline and shall be free from all extraneous matter that may damage the pipe, pipe coating, or sleeving.
      • 4 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.
      • 5 Suitable measures shall be taken to prevent soil or other material from entering pipes, and to anchor each pipe to prevent flotation or other movement before the Works are complete.
      • 6 Where pipeline marker tape is specified, it shall be laid between 100 mm and 300 mm above the pipe.
      • 6.1.1 Pipe Bedding
      • 7 Bedding for pipes shall be constructed by spreading and compacting granular bedding material over the full width of the pipe trench. After the pipes have been laid, additional material shall, if required, be placed and compacted equally on each side of the pipes, and where practicable, this shall be done in sequence with the removal of the trench supports.
    • 6.3.2 Concrete Protection to Pipes
      • 1 Pipes to be bedded on or cradled with concrete shall be supported on precast concrete setting blocks. The top face of each block shall be covered with two layers of compressible packing complying with BS 743.
      • 2 Concrete provided as a protection to pipes shall be Grade C20, placed to the required depth in one operation.
      • 3 Where pipes with flexible joints are used, concrete protection shall be interrupted over its full cross-section at each pipe joint by a shaped compressible filler of bitumen impregnated insulating board to BS 1142 or equally compressible material. The thickness of the compressible filler shall be in accordance with Table 6.1.
  • Table 6.1 Thickness of Compressible Filler
Nominal bore of pipe (mm)Thickness of compressible filler (mm)
Less than 450 18
450 to 1200 36
Exceeding 1200 54
      • 4 Rapid hardening cement shall not be used in concrete for the protection of plastics pipe.
      • 5 Plastics pipes shall be wrapped with a layer of plastic sheeting complying with a composition in accordance with Clause 3 of BS 6076 and a nominal thickness of 125 microns before being surrounded by concrete.
    • 6.3.3 Completion of Pipe Surround
      • 1 Fill material shall, where required, be placed and compacted over the full width of the trench in layers not exceeding 150 mm before compaction, to a finished thickness of 250 mm above the crown of the pipes.
    • 6.3.4 Backfilling
      • 1 Backfilling shall, wherever practicable, be undertaken immediately the specified operations preceding it have been completed. Backfilling shall not, however, be commenced until the works to be covered have achieved a strength sufficient to withstand all loading imposed thereon.
      • 2 Backfilling around existing structures shall be undertaken in such manner as to avoid uneven loading or damage.
      • 3 Filling material to excavations shall be deposited in layers not exceeding 250mm unconsolidated thickness and compacted to 95% modified proctor.
      • 4 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 minimise the danger of collapse. All voids formed behind the supports shall be carefully filled and compacted
  • 6.4 GULLIES AND DRAINAGE CHANNELS
    • 6.4.1 Gullies
      • 1 Gullies shall incorporate rodding eyes. Rodding eyes shall be fitted with rubber stoppers during normal operation.
      • 2 All gullies shall be trapped to prevent unwanted odours escaping from the drain.
      • 3 All gullies shall incorporate aluminium silt buckets.
      • 4 The Contractor shall ensure that the gully outlet and the outlet pipework are compatible.
      • 5 Gully covers, gratings and frames shall comply with the relevant provisions of BS 497: Part 1 or BS EN 124.
      • 6 The class of gullies covers, gratings and frames shall be as described in the Project Specification or as shown on the Project Drawings.
    • 6.4.2 Pre-formed Gullies
      • 1 Precast concrete gullies shall comply with the relevant provisions of BS 5911: Part 2 and Section 5 - Concrete.
      • 2 Vitrified clay gullies shall comply with the relevant provisions at BS EN 295: Part 1 or BS 65.
      • 3 Polypropylene gullies shall be of a type detailed in the Project Specification or shown on the Project Drawings and shall be obtained from a reputable manufacturer as approved by the Engineer.
      • 4 Cast iron gullies shall be of a type detailed in the Project Specification or shown on the Project Drawings and shall be obtained from a reputable manufacturer as approved by the Engineer.
      • 5 Pre-formed gullies shall be bedded and surrounded with Grade C20 concrete to the thickness described in the Contract Documentation.
      • 6 Frames shall be bedded in mortar on two courses of Class B engineering brickwork or precast concrete gully cover slabs. Precast concrete gully cover slabs shall comply with the relevant provisions of BS 5911: Part 2 and Section.
    • 6.4.3 Drainage Channels
      • 1 Precast concrete drainage channels shall comply with the relevant provisions of BS 5911: Part 2 and Section 5 - Concrete.
      • 2 Drainage channel gratings and frames shall comply with the relevant provisions of BS EN 124.
  • 6.5 SOAKAWAYS
    • 6.5.1 General Requirements
      • 1 Soakaways shall not be constructed closer than 10 m from a building or in a position where the ground below foundations is likely to be adversely affected.
      • 2 Excavation round the soakaway shall be backfilled with a band of 40mm nominal single size stone to provide a permeable surround to the soakaway. The permeable surround shall be fully wrapped in a geotextile fabric. The dimensions of the band shall be as shown on the Project Drawings.
  • 6.6 MANHOLES AND CATCH PITS
    • 6.6.1 General Requirements
      • 1 Bases and walls to manholes and catch pits shall be cast in situ using Grade C30 concrete.
      • 2 Cover slabs to manholes shall be precast using Grade C40 concrete and shall incorporate an integral GRP liner with a minimum thickness of 3.5mm. The vertical sides of the openings of cover slabs shall be formed of filament would GRP pipe and soffits shall be formed of GRP sheet.
      • 3 The Contractor shall provide the Engineer with a seven year unconditional guarantee against failure of all GRP linings whether caused by defective materials or workmanship. The guarantee shall be valid from the date of completion of the installation and must be handed over to the Engineer before the issue of the Final Completion Certificate.
      • 4 Unless otherwise stated in the Project Specification or shown on the Project Drawings, manhole inverts and benching shall be formed in Grade C20 concrete. Where there is no change of diameter, the invert of the benching shall follow the same gradient as the outgoing pipe.
      • 5 Where a high strength concrete topping (granolithic finish) is required, the invert and benching shall be formed in Grade C20 concrete, and the topping shall be applied as soon as practicable thereafter.
      • 6 All concrete works, including benching, shall comply with the relevant provisions of Section 5 - Concrete.
      • 7 Step irons shall comply with the relevant provisions of BS 1247:Parts 1, 2 and 3.
      • 8 Covers and frames shall comply with the relevant provisions of BS 497:Part 1 and have a minimum clear opening of 600 mm diameter if circular or 600 x 750 mm if rectangular. All covers shall have closed keyways.
      • 9 The Contractor shall prepare a standard record sheet for every manhole and catch pit to the approval of the Engineer.
      • 10 Testing of manholes and catch pit chambers shall be as detailed in Part 6 of this Section.
  • 6.7 CONNECTION TO GOVERNMENT MAIN
    • 6.7.1 General Requirements
      • 1 Connection to government mains shall be done at manholes. Pipe saddles and oblique junctions will not be permitted.
      • 2 Where possible and practicable, connections shall be made to future connection ports in existing Government manholes. The caps on future connection ports to which connections are made shall be cleaned and delivered to the government stores on completion of the work.
      • 3 Where it is not possible or practicable to utilise future connection ports in existing manholes, connections shall be made by either breaking into existing manholes or constructing new manholes on existing mains.
      • 4 If it is necessary to break into an existing manhole, the Contractor shall break into the manhole wall, insert pipework, break out the existing benching, construct benching to suit new connection and make good. If necessary, the Contractor shall relocate the access ladder and the cover slab to suit the new benching layout.
      • 5 Manholes built on an existing Government mains shall be constructed in accordance with Clause 6 of this Part. On completion, such manholes shall become the property of the government.
      • 6 The Contractor shall be responsible for all over-pumping operations associated with making connections to Government mains:
      • 7 When a connection is made to an existing manhole in an area with high groundwater levels, the Contractor shall undertake the following if instructed to by the Engineer.
        • (a) undertake a CCTV survey and deflection test between the manhole immediately upstream and the manhole immediately downstream of the manhole to which the connection is to be made before commencing dewatering operations.
        • (b) construct two mass concrete stanks round the base of the manhole to prevent groundwater from flowing into the excavation. The stanks shall be positioned each side of the proposed connection and shall extend across the full width of the excavation. The stanks shall be in place before any dewatering takes place.
        • (c) undertake a CCTV survey and deflection test between the manhole immediately upstream and the manhole downstream of the manhole to which the connection has been made when work is complete and groundwater levels have returned to their natural levels.
        • (d) the Contractor shall submit all CCTV survey data and deflection test data to the Engineer. Such data shall be used to determine whether any damage has been caused to the existing main by the Contractor while carrying out his work.
        • (e) the Contractor shall be responsible for rectifying any damage caused as a result of his work.
        • (f) the Contractor shall submit his proposals for carrying out remedial works to the Engineer for approval prior to starting such work, should it be necessary.

END OF PART