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DRAINAGE (Defects (Strucutral (Delamination, 3rd Party Damage, Poor Joints…

- - - - H1 - FOUL WATER DRAINAGE
        
        REQUIREMENT
        An adequate system shall carry foul water from appliance to a
        
        public sewer
        
        private sewer to public
        
        Septic tank/cesspool
        
        P1 - Sanitary Pipework
        
        Traps
        
        Min depths of water seal traps to prevent foul air
        
        Branch Discharge Pipe
        
        No discharging into open hoppers
        
        Use of sub-stacks for GF appliances
        
        Only discharge into drain if depth is <1.3m
        
        No cross flow
        
        Bends and min. height to discharge to stack
        
        Branch - falls @ 18 and 19mm/m (vented stacks where distance between stack and appliance is large).
        
        Ventilating pipes - connect to D.P within 750mm of trap
        
        B.V.P should finish 900mm above any opening of the building nearer than 3m
        
        Discharge Stacks
        
        Discharge to drain
        
        Large radius at bend and
        at least 200mm at centre line
        
        Size
        
        Urinals @ 50mm / WCs @ 75-100mm
        Dia. not reduce in direction of flow
        
        Sub stacks
        
        Used if it connects to a V.D.S or Vent'd drain
        
        Materials for pipes/ fittings/ joints
        
        In accordance with BS standards
        
        P2 - Foul Drainage
        
        Outlets to connect to public/private sewer
        
        Simple layout
        
        Drains running under building to have 100mm granular around pipe to overcome settlement/subsidence
        
        Pipes penetrating wall - joints within 150mm of wallface and 600mm joint cts OR 50mm space around pipe where lintel provided
        
        Pipe run near buildings -Where <1m fill concrete fill trench
        
        Flow Rates @ 2.5 litres//sec for single dwelling
        
        Beddng and Backfilling
        
        limits for cover between 600mm - 8m
        
        Protection at shallow depths - backfill/ slab/ compressible mateiral
      - H3 - RAINWATER DRAINAGE
        
        Requirement
        -Adequate provision for RW from roof
        
        Paved areas should be adequately drained
        
        RW shall discharge to 1)Soakaway 2) Watercourse 3) Sewer
        
        Section 1
        Gutters/RW pipes
        
        Rainfall Intensities
        
        Gutters
        
        Gutter size dependent on:
        Roof area
        Pitch
        Fall of gutter
        
        Rainwater Pipes
        
        Discharge into drain; gulley; or surface if drained
        
        Rainwater Harvesting
        
        Section 2.
        Drainage to
        Paved Areas
        
        Design falls min 1:60 max 1:40
        
        Away from buildings
        
        pervious vs impervious
        
        contaminants/ pollutants
        
        Discharge into soakaway/ infiltration system
        
        BS EN 752-4:1998
        
        Section 3
        Surface Water Drainage
        
        Discharge
        
        Soakaway
        
        Watercourse
        
        EA consent
        
        Main Sewer
        
        Combined Sewer taking
        foul and surface water
        
        2 more items...
        
        Rainfall Intensities
        0.014litres/second/m2
        
        S/W Sewers
        Min 75mm dia for 1 dwelling
        Min. 100mm for +1 dwelling
        
        Contaminated drainage should be separate or treatment system
      - H4 - BUILDING OVER SEWERS
        
        Requirement
        Applies to any work: (within 3m of ctr line of drain in silty soils):
        
        over drain/sewer shown on 'map of sewers'
        
        to any site that may interfere with use, obstruction of access to drain/sewer shown on Map
        
        Map of Sewers - Map kept by S.U under Section 199 of Water Industry Act 1991
        
        Should consult drain owner or S.U if construction near/over drain
        
        Extension/ Underpinning
        
        Satisfactory diversion
        route so as not to obstruct
        work to replace drain/sewer/main
        on its present alignment
        
        Construction shouldn't remove maintenance access
        where currently exists UNLESS alternative access can be provided
        
        Length of drain under building should be <6m unless
        permission granted by owner of sewer
        
        Risk of damage to building from failed drain is not excessive
        due to nature of ground, condition/location of main; nature/volume of main and design&construction of foundation/building
        
        Special measures
        
        Required if building over/within 3m
        
        On non cohesive soils (find sands/ peat/silts)
        
        of any rising main
        
        any drain/sewer constructed by brick
        
        Any drain/sewer in poor condition
        (crack/fracture/deformed by +5%)
        
        Not required if
        
        Above foundations
        
        Above water table
        
        More than 1m deep
        
        Protection from Settlement
        
        100mm granular/flex filling
        provided around pipe where drain runs under
        building
        
        Where drains run below building is <2m depth, foundations should be extended locally so drain passes through wal
        
        Lintel to foundation where drains > 2m deep to invert are laid
        beneath foundations. Span of lintel should extend 1.5m either side of pipe
      - H5 - SEPERATE SYSTEMS OF DRAINAGE
        Applies only to extensions/erections of buildings where it
        would be practical to discharge effluent separately.
        
        Requirement
        Systems for discharging RW to a sewer should be
        separate from conveyance of foul water from building - aiming to minimise volume of RW entering foul sewer systems which can overload sewer and cause flooding.
        
        Separate Sewer Systems Provided
        
        Where buildings are drained to public sewer system, and S.U
        provides separate systems, separate drainage systems will be required to comply with Section 106 (Rights to communicate with Public Sewer System- Water Industry Act 1991.
        
        Separate Systems Proposed
        
        Where a combined sewer exists, but a separate sewer is under construction, separate foul and surface water should be provided so to minimise disruption to occupiers when change-over occurs
        
        Beware of contaminants where separate systems are proposed.
      - H6 - SOLID WASTER STORAGE
        
        Requirement
        Adequate provision shall be
        provided for storage of solid
        waste and from place of storage
        to collection point
        
        Environmental Protection Act 1990
        
        Capacity
        0.25m3 or
        Low Rise <4Flrs- Moveable units - 1.2 x 1.2 area<4Flrs - Chute
        
        Siting not to exceed >25-30m distance
      - H2 - WASTE WATER
        TREATMENT SYSTEMS & CESSPOOLS
        
        Requirement
        Shall be sited so doesn't effect heath/contaminate water course/ means to empty&maintain; adequate capacity
        
        At least 7m away from habitable part of a building
        
        Size @ 2,700 for upto 4 users - 180litres pp after that
        
        Drainage to fields to be >10m away from watercourse; 15m away from buildings/ afar from other drainage fields
        
        Maintenance
- - - - 1991 - 2001
        LAs Phases Out
        
        2011
        Adoption of existing
        private sewers and lateral drains
        New drains private until transferred to Water Authority