Sanitary System Task 5

SANITARY SYSTEM

Introduction:

The sanitary sewer is a system of underground pipes that carries sewage from bathrooms, sinks, kitchens, and other plumbing components to a waste water treatment plant where it is filtered, treated and discharged. The storm sewer is a system designed to carry rainfall runoff and other drainage.

A sanitary sewer or "foul sewer" is an underground carriage system specifically for transporting sewage from houses and commercial buildings through pipes to treatment facilities or disposal. Sanitary sewers are part of an overall system called a sewage system or sewerage.

Sewage may be treated to control water pollution before discharge to surface waters. Sanitary sewers serving industrial areas also carry industrial wastewater.

Separate sanitary sewer systems are designed to transport sewage alone. In municipalities served by sanitary sewers, separate storm drains may convey surface runoff directly to surface waters. Sanitary sewers are distinguished from combined sewers, which combine sewage with stormwater runoff in one pipe. Sanitary sewer systems are beneficial because they avoid combined sewer overflows.

Background of sanitary system:

Sewage treatment is less effective when sanitary waste is diluted with stormwater, and combined sewer overflows occur when runoff from heavy rainfall or snowmelt exceeds the hydraulic capacity of sewage treatment plants. To overcome these disadvantages, some cities built separate sanitary sewers to collect only municipal wastewater and exclude stormwater runoff collected in separate storm drains. The decision between a combined sewer system or two separate systems is mainly based on need for sewage treatment and cost of providing treatment during heavy rain events. Many cities with combined sewer systems built prior to installing sewage treatment have not replaced those sewer systems.

Drainage above ground

Waste Pipe Connections:-

• Where an appliance is installed it will need to connect to ‘suitable system of drainage’  
• This is done by installing a ‘waste’ fitting called a trap to the appliance & connecting it to the discharge pipe 
• Each type of appliance has a standard size of waste & trap, as follows:

Type of appliance	Waste fitting size (inches BSP)	Discharge pipe & trap size (mm)
Sinks, showers, baths, washing machines & trough urinals	1.5	40
Wash basins, bidets, drinking foundation & bowl urinals	1.75	32
Stall & slab urinals	2.5	65

• Appliances such as sinks & baths use a combination overflow (o/f) & waste fitting (the o/f connects to the waste before the trap) 
• Appliances such as Belfast sinks, bidets & wash basins have an integral o/f so they need a ‘slotted’ waste  
• Some appliances such as showers have no o/f at all, & may use an ‘unslotted’ waste

Traps:

• A trap is a fitting attached to the waste which is designed to retain a water seal between the appliance & the drain to stop smells coming back into the room 
• There are P, S, running, bottle, integral & resealing traps
•  For discharge pipes of less than 50 mm, the trap seal should be 75 mm
•  For discharge pipes above 50 mm, only a 50 mm seal is required
•  If the appliance is fitted with spray taps & has no plug (basin or shower), then a 50 mm trap seal may be used
•  Tubular traps are less prone to blockage than bottle traps
•  Resealing traps may be used where the seal could be lost
•  The trap to a WC is an integral part of the WC. It has a 50 mm deep seal & the outlet is approximately 100 mm in dia
  
  

Discharge Systems:- 

There are 4 types of discharge systems:-

1. Dual Pipe System 

• Oldest system - based on soil & waste fittings kept separate until below ground
•  Soil stack discharges via slow bend, with ventilation (or anti-siphon ) pipe connected to each appliance
•  Ventilation pipes & stacks venting above roof with cages to prevent birds/matter entering
•  Waste stack discharges to a common gully with ventilation pipes also fitted to each appliance
•  Waste appliance traps may be 38mm (1 1/2”) seal
  
  
  
  

2. Single Pipe Ventilated System

• Has a single stack discharging via slow bend to drain
•  Stack vents above roof via cage
•  Waste fittings have 75mm deep seal traps
•  Ventilation pipe fitted to each discharge branch – not each appliance
•  Used where long individual branches are required
•  The ventilation pipe may have its own separate vent, or return back into the stack vent at the top

 

3. Single Pipe Ventilated Stack System

• Similar to Ventilated System, but only the stack is ventilated (mainly because of compression)
•  None of the branch pipes are ventilated
•  Only suitable where appliances are closely grouped to the stack

4. Single Stack System

• By far the most common with domestic dwellings
•  No ventilation pipes because stack is large enough to prevent pressure fluctuations
•  All waste fittings have 75mm deep seal P traps
•  Main stack is 100mm minimum with slow radius bend at base
•  Each branch connection should not cause ‘cross- flow’ into other branches
  
  
  

Drainage below ground

The combined system

• Combined drainage system is used in the cases when vertical or horizontal drainage cannot provide required capture of groundwater.
• This type of drainage is used both in homogeneous and stratified soils of different permeability and large thickness of filtering stratum.

Structure of combined drainage:

1-      Ground surface, 2- low permeable stratum,

                                3 – water -bearing stratum; 4 – screen of well-amplifier; 
                                5 – well-amplifier; 6 – open and closed horizontal drains

The separate system

• 1       A separate drainage system is one were the foul water and the surface water are always kept separate.
•       This is shown in the two previous diagrams
•       When a separate system is used then the sewerage treatment plant will not get overloaded in periods of wet weather.

The partially separate system

•          A partially separate system is a combination of a combined sewerage system and separate sewerage systems.         
•         This type of sewerage system helps decrease the load from a combined sewerage system and the lag of separate sewerage systems.
•        With trenchless technology, it is now possible to create a separate sewerage system with minimum disturbance to the old sewer network.

Sanitary Fitting

• The fitting are required in building to perform different type of functions. Sanitary fitting are glazed chinaware. The fitting also are designed and shaped that they have non- absorbent surface which can be cleaned easily.

CISTERN

•  Cistern are commonly applied and incorporated in most water closet system.
•  Cistern are also used to flush away the content of soil fitting to the drain.
•  Then, its made up of materials from plastic or ceramic. 
•  After that, build cistern have dual flush functions.
•   In B11, the cistern applied in the toilet is without dual function.

Washdown Type

Disc Type

WATER CLOSET

• Water closet are usually subdivided according to where tey are mounted (wall mounted and floor mounted) and how they are flush (tank type and flush vavle type). 
•  The outlet may be obtained left or right hand and also ‘P’ or ‘S’ as shown and its will be flushed from a high or low level flushing cistern.
•  The high level cistern provide certain provide more effective flush compare to low level cistern.
• In B11 building water closet of washdown and disc type is available.

  

 Washdown in B11 Building

Disc Type

URINALS

•  Designed to accept and dispose of liquid human waste only.
• The type of urinal seramic slab, stall type and bowl type.
• The slab type is cheaper than stall type, but is does not provide the same degree.
• The installation of ceramic bowl-type urinal which have less fouling area then the slab and stall urinals.
• This fitting is not available in B11 Building. 

WASHBASINS

• Many wash basins designed are available, ranging from surgeon’s to small hand basin.
• They can be obtained to fit into a corner of the room and may be surported on brackets, a pedestal or by a ‘built in’ corbel.
• Photo show below is the basin in B11 Building for the washing purposes.

 

  

                                                                      Wash Basin

SINKS

• Sinks of all types are in wide use in a multitude of different applications.
• Sinks also can be made of porcelain, stainless steel. Plastic, fiberglass or any other nonporous material.
• Sinks can be wall mounted, floor mounted, set into countertop or free standing with legs.
• Sinks is not availabe in B11 Building.

SHOWERS

• This device for washing, typically consisting of an enclosed area an overhead nozzle.
• Human stands in enclosed area while nozzle spray water down on the body.
• Used for hygiene and washing perposes.
• In B11 Building, this its not available.

 

TRAPS

• This as fitting at the end of soil pipes of waste pipes to prevent foul gases coming out from the soil pipe or waste pipe.
• This fitting is available in toilet of B11 Building.

Ventilation:-

• Essential to allow air in & out of drainage systems to ensure atmospheric pressures e.g. if negative pressures inside pipe-work – trap seals may be lost
•  By allowing air through the system, any foul matter adhering to inside of pipe would soon dry & be washed away
•  Venting pipes prevents the build up of hazardous gasses such as methane
•  Air enters the drain at low level (manholes etc.) & rises through the stack by convection currents
•  The termination of the stack should be in a position that dies not cause nuisance or health hazard
•  If vent within 3 m’s of window opening – vent should be 0.9 m’s higher — Every vent should be fitted with a domical cage to exclude birds nesting etc.
•  Vent may be reduced in houses up to 2 storeys but must be 75 mm minimum
•  Discharge stacks may terminate with an ‘Air Admittance Valve’
•  These valves are designed to allow air into the stack but not out of
•  They must not be fitted to:-
•  drains which have a record of surcharging
•  drains which an interceptor fitted

• Limited in number to:-
•  where 5 houses connect to same drain – head of drain to be conventional vent
•  or where >5 houses head of drain & every 6th vent

Stub Stack:-

• A short 100 mm dia. discharge stack which is capped with rodding eye at the top, but connected to ventilated stack no more than 6 m’s away
•  This may be extended to 12 m’s where a group of appliances is fitted
•  Any WC connection should be no more than 1.5 m’s above invert & waste conns 2 m’s max.

Case Building ( Block 11 )

Student have the right to basic facilities such as school toilets, safe drinking water, clean surroundings and basic information on hygiene. Base on our case building, Block 11 in Faculty of Build Environment, the list below shows the sanitary appliances and fittings having in the building.

1) Water closets ( WCs )
      -

Washdown

Disc Type

2) Basin