Drain_and_sewer by ajizai

VIEWS: 20 PAGES: 16

									                   CENTRE FOR HIGHER EDUCATION

                   CONSTRUCTING ARCHITECT EDUCATION




Drains and sewers




     August 2004
        TJA
List of contents
1. Drains ........................................................................................................3
2. Frost............................................................................................................3
3. Dimensioning fall in pipes ........................................................................4
  Crossing from standing to laid piping. .......................................................................................... 4
  Connecting laid pipe to laid pipe. .................................................................................................. 5
  Connecting stand pipes to laid pipes ........................................................................................... 5
  Connecting stand pipes to laid pipes ........................................................................................... 6
  Pipe dimension in soil. .................................................................................................................... 6
  Routing pipes outside the building. .............................................................................................. 6
  Local planning restrictions ............................................................................................................. 7
  Pipe connections ............................................................................................................................. 7
5. Strengthening foundations .................................................................7
6. Pipes crossing........................................................................................9
7. Cleaning access .....................................................................................9
8. Service pipes ........................................................................................10
9. Rainwater ...............................................................................................10
  Dry pipes – these are rain water pipes which do not always contain water. ....................... 10
  Example: - just before a rainwater well. ................................................................................... 10
  Rain water wells ............................................................................................................................ 10
  Sand trap Drain pipes must be protected from blockages caused by sand, gravel, paper,
  leaves and twigs etc Sand traps should be used by: .............................................................. 10
  Drain from outside basements shaft .......................................................................................... 11
  Drains from light shaft................................................................................................................... 11
10. Drain water systems .........................................................................12
  Separate systems.......................................................................................................................... 13
  Branch pipes .................................................................................................................................. 13
  Falls in terrain ................................................................................................................................ 13
11. Materials...............................................................................................14
12. Wells .......................................................................................................14
  Inspection chambers. ................................................................................................................... 15
13. Ventilation of waste water pipes above the roof. .....................16
                                Drain and sewer systems

1. Drains
Difference in height between floor level FL and the bottom of the pipe (L) is normally about 250 mm.
                           FL
                           FL                FL
                                              FL




                       L

                                                   FL
                       FL




FL = Floor level L = Bottom of pipe

   a) The radius bend is normally 250 mm under floor level (FL), when the bend is placed with the
      collar at floor height. (a)
   b) A floor drain with water trap (b) is at least 250 mm under floor level - depending on the
      system used.
   c) In a floor drain with a water trap followed by a bend the height difference can be from 250 -
      400 mm.
   d) A pipe must always be laid so that the spigots do not get embedded in the concrete floor,
      especially when there is heavy traffic on the floor.

2. Frost
Frost-free depth is normally 750 mm below the ground level - measured from the bottom of the
drain.

In the following cases a lower frost-free depth is permitted:
     Dry pipes for rainwater (300-400 mm)
     Water traps or inspection wells by basement stairs and similar (250 mm below the floor)
     Pipes in drain systems with soakaway or seepage systems (600 mm)
     Insulated pipes (see diagram below)
     Drain pipes by heated buildings (600 mm)




Polystyrene insulation above a pipe, which could freeze.




                                                                                        Page 3 of 16
                               Drain and sewer systems

3. Dimensioning fall in pipes




                                                       FD




A straight run from the floor drain FD to the main pipe A would give a deeper well B and extra soil
excavation –(hatched area).

A constant 35 ‰ fall gives the best self-clearing function, but it is an expensive solution, because
there is so much soil to excavate.

Big falls => deep pipes - which can be expensive when strengthening foundations.

                                                                          The cheapest solution is to
                                                                          choose a minimum fall for
                                                                          each pipe.


                                                                          In practice the pipes are laid
                                                                          in a straight line and only
                                                                          have a change in fall in
                                                                          wells or bends.




4. Waste water pipes

Crossing from standing to laid piping.
(Stand pipes are also known as down pipes)

Connections can be     ade with an 87–88     short branch pipe, if:

      No connections to the standing pipe are more than 2 m above the bend - and not closer than
       1 m to the laid pipe.
      The height from the highest connected water trap to the bend is not more than 10 m.
      There are a maximum of 3 toilets connected to the down pipe

                                                                                          Page 4 of 16
                              Drain and sewer systems




                                                  Max 10m
                                                  Max 3 WC’s




          No connections

n othe cases the bend should be     ade up of   x 5   bends, or an 87 –88˚ la ge adius bend, o a
VA-approved bend .

Bends in laid pipes
                                                                Pipes with only one joint pipe, can
                                                               use a adius bend up to 88 .



                                                               A: Bad solution.
                                                               B: Good solution - large radius.




 o pipes with o e than joint pipe, it is eco     ended to use 5
 . Bends. f the change in di ection is 9  put a straight pipe
(min 300 mm) between the bends.


Connecting laid pipe to laid pipe.




                           Double branch
                           pipes must not be
                           used!!!



                                                                                        Page 5 of 16
                              Drain and sewer systems

Connecting stand pipes to laid pipes



 Stand pipe                Laid pipe




                                                                           pipe
                                                                     Stand Standing pip



                     NOT okay


      Side connection is recommended => always use it!
                                                    Laid pipe




 Pipe dimension in soil.
The minimum dimension for pipes in soil is Ø 75 mm.
If one or more toilets are connected to the system the dimension must be at least Ø 100 mm.

Routing pipes outside the building.
For better accessibility pipes should be led as directly as possible out of the building.
This is not an absolute requirement, if it makes the sewer system unreasonably expensive.

Recommended distances between building and outside sewer systems:

                       Standard

                                                Light
                                                shaft




                                            Staircase
                                            foundation


   a) Shows normal or standard distance, but it can be larger or smaller - depending on other
      installations, adjoining sites and foundations etc.
   b) Gives a reasonable minimum distance to light shafts / stairs etc all building – mainly to give
      space for digging / excavation.
   c) Gives the normal distance between pipes in a separate (2 pipe system) - depending on
      where the well is placed.




                                                                                          Page 6 of 16
                               Drain and sewer systems


Local planning restrictions




 Building line

 Boundary



Local authorities must give permission for installations to be placed outside the building line –a).
If any roads are planned to be built then pipe must run as shown in b).

Pipe connections

Pipe connections always state two levels:
    Main pipe - bottom joint level (BL) (Here BK)
    Service pipe – bottom joint level (BL) (Here BK)

The levels can be placed as shown:




                                    BL 14.17                   BL 14.36




5. Strengthening foundations
A new standpipe must be led to the system A-B. The best solution is number 1, but the cheapest is
probably number 4. Pipes led through foundations should not only be restricted to a right angle - 4
and 5.




                                                                                           Page 7 of 16
                               Drain and sewer systems




Use a smaller angle (as in 2) if it gives a better water run. Very small angles – as in b - are not good,
but they can be used if the foundation is strengthened.

The pipe should not be directly embedded – there should be space around the pipe - 50-100 mm is
usually sufficient.




                                                         Hole
                                                          Hole




If the pipe passes under the foundation -
up to 500 mm below it - it is necessary to
strengthen the foundation:-




If the pipe is more than 500 mm below
the foundation, the foundation must be
reduced :_




                                                                                            Page 8 of 16
                              Drain and sewer systems




6. Pipes crossing
Pipes or channels for :                          Normal depth from ground to the top of the
                                                 pipe in cm
Water                                            120-140
Gas                                              60-80
District heating                                 Very varied
Waste water                                      Min. 75


7. Cleaning access
Cleaning access (rodding access) in waste water and combined piping should be as follows:
    Max length under ground slab – 20 m.
    Where a down pipe joins laid piping.
    After a total direction change of 9 (base bends not included)
    Max 40 m between 2 wells in terrain.
    Max 20 m between final cleaning access in the building and the first cleaning access in soil.
    In buildings where pipes crossover to pipes in soil. (Cleaning access in drain pipes in
       basement).




                                                                                       Page 9 of 16
                               Drain and sewer systems

8. Service pipes
Service pipes must be able to clean:




                                                                           Rodding / cleaning access




          Main pipe                         To place in a public area needs a special licence

Cleaning access for service pipes:
A:          If connection to the main pipe is not in an access well/inspection well/flushing well, the
            distance to the first cleaning access point should be max 20 m.

B:           If connection is in an access well/inspection well/flushing well, the distance to the first
             cleaning access should be max 40 m.

C & D:       Where the building is built on the site boundary cleaning access to the
             service pipe must be straight inside the building.

9. Rainwater
                 Dry pipes – these are rain water pipes which do not always contain water.
                                    Example: - just before a rainwater well.


                                    Dry pipes before sand-trap
                                        Depth 300-400 mm
                                        Fall     ‰

                                    After first sand-catch:
                                         Frost free depth 750 mm
                                         Fall      ‰.

                                    Rain water wells
                                    Rainwater wells are small wells with sand and water traps.

                                  Sand trap Drain pipes must be protected from blockages
caused by sand, gravel, paper, leaves and twigs etc Sand traps should be used by:
    Surface drains - from paved or non-paved areas.
    Down pipes from the roofs or similar which may have leaves and twigs on them.
    Drain water installations before connection to a pump well or sewer system.

                                                                                           Page 10 of 16
                               Drain and sewer systems

Drain from outside basements shaft
A basement shaft executed as shown:




       Normally bottom of
              the foundation

Note that the bottom of the shaft is about 50 mm lower then the basement floor, and the foundations
around the bottom are 600 mm because of the risk of frost.

The best way to remove the water from the basement shaft is shown below:




                                                  FD
                                                  FD




Separate systems
The drain from the basement shaft must be led to the rain water system. This can be difficult
because the basement shaft is normally placed much deeper than the rain water system. If we want
to lead the water to the waste water system it can only be done after permission from the local
authorities.

Drains from light shaft




                  FD                                   FD




Drain from individual light shafts.



                                           Fall




                                      Terrain

                                                                                     Page 11 of 16
                                     Drain and sewer systems

Drains from other light shafts.

Another possibility is to lead the water to the drain water around the house:


                                       FD             Section
                                                      Section
                                                      Fall




                                                     Filter material
                                                    Fall
                                            Drain




                          FD




                          Section in plan
                          Fall
Separate system
Drains from light shafts must be led to the rain water system - possibly by pumping. Connection to
the waste water system can only be done with local authority permission.

10. Drain water systems
Fall 3-5 ‰.
The drain water pipe must not be less than 70 mm.
In heated buildings with ground slabs the frost-free depth is 600 mm.

Drain water pipe around the house:


               Terrain
                Terrain
                Fall


         Soil
         Foundation
         Filter material (min.0,1 m around the
         pipe)
         Drain pipe (minimum fall 3 ‰)




        Maximum excavated depth




                                                                                      Page 12 of 16
                               Drain and sewer systems




                                                    All bends must be able to be cleaned from both
                                                    sides of an access well.


                                                    It is not allowed to lead surface water to the drain
                                                    system – except for limited amounts of rain water,
                                                    from light shafts or roofed basement shafts which
                                                    could, for example, be led directly to the drain
                                                    around the house.

Separate systems
The drain water must be lead to the rain water system. Connection to the waste water system is
normally not allowed, but it may be if permitted by the local authorities.

Branch pipes




          Drain                      Capillary break
          Drain                     Capillary breaking layer

                               Branch pipe




The capillary breaking layer below the terrain deck is nearly never in danger for impounded water.

Falls in terrain
3 m from the building there must be a fall of:
          ‰ fo soil.
        5 ‰ fo flagstone paving.

Falls can be halved for buildings with no basement


            Correct fall away from building




                                                                                          Page 13 of 16
                                Drain and sewer systems

11. Materials
To make sure that the demands for a drain/sewer installation are complied with, drain/sewer
standards (DS 432) contain demands relating to the components and materials:

      Components and materials must comply with the functional demands in the standard.

Manufactured components in or connected to drain installations, must either be:

      App oved by the “Ministry of Housing”, unless the components had previously been
       approved according to provisions existing at that time.
      Are CE-labelled – showing that product conforms to agreed standards or is included in one
       of the European technical agreements.

Included under the Ministry of Housing “Bolig iniste iet” app oved sanction or control systems.

Ministry of Housing label - (Boligministeriets VA-sanction)




In the future it is expected that the VA- label will be replaced by a CE label


                          CE – ”Ce ticate
                          European label ”



12. Wells
Wells can be used for changes in fall, direction and dimension of the pipes - unless they are used for
cleaning access.

It is best if there is a maximum of two changes of di ections of 5˚ between two wells so that the
total change of di ection is axi u 9 ˚.

It is possible to have more than a 9 ˚ change of direction in an inspection chamber.




Inspection chamber. Change of pipe direction.

Changes of direction greater than 9 ˚ are possible but are not advised – they should be avoided.

Wells are also used as a collecting point for many inlets. In soil pipe connections are usually done at
an angle of ≤ 6 ˚. It is not permitted to use double branch pipes.




                                                                                         Page 14 of 16
                               Drain and sewer systems




Inspection chambers - Pipe connections

In wells with an internal diameter of 1, 0 m there should not have more than 4 inlets. If more are
necessary the diameter must be 1.25 m.

 Inspection chambers.
An inspection chamber is a cleaning - and inspection well with access to the bottom of the well and
the connection of the pipes.

                                        Cover
                                        Cover frame



           Connecting                   Top ring
           piece (cone)




    Side pipe
    (Rain water)




                                                                Section A-A




                                        Bottom canal
                                        Berm




                                             Side pipe
                                             (waste water or rain water)
Basic principles of an inspection chamber


                                                                                         Page 15 of 16
                              Drain and sewer systems

13. Ventilation of waste water pipes above the roof.
The pipe must be at least 50 mm above the roof surface to avoid rain water from getting into the
pipe.

Where the ventilation is led out of the roof, we must take into account windows, doors, other
ventilation pipes, air inlets, roof terraces, other residences and the wind.

Roofs with a pitch of less than 3 ˚ to the horizontal, the pipe must be at least 0,3 m above the
topmost hinged window or doors from habitable rooms, kitchens, bathrooms, toilets, staircases and
entrances and from pipes or ducts for natural ventilation, if they are closer than 1 m measured
horizontally:




Positioning of waste water system ventilation pipe - roof pitch under 30˚.

Roofs with a pitch g eate than 3 ˚ with ho izontal the pipe f o ventilation of the waste
water pipe must be at least 0,8 m above the highest hinged windows or doors from
habitable rooms, kitchens, bathrooms, toilets, staircases and entrance and from pipes from
canals from natural ventilation, if they are closer than 3 measured horizontally.




Positioning of waste water system ventilation pipe - roof pitch greater than 30˚.




                                                                                       Page 16 of 16

								
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