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close this bookResidential and Non-Residential - Drinking water installations and drainage requirements in Nepal (MTC - SKAT, 1988, 188 p.)
close this folderPART 2 - DRAINAGE REQUIREMENTS
View the document1. SCOPE
View the document2. FIELD OF APPLICATION
View the document3. TERMS AND DEFINITIONS
View the document4. PRINCIPLES OF INSTALLATION
View the document5. PRINCIPAL REQUIREMENTS FOR PARTS OF PIPELINE
View the document6. PRINCIPAL REQUIREMENTS FOR DRAINAGE APPLIANCES
View the document7. PRINCIPLES FOR THE PLANNING AND FITTING OF DRAINAGE PIPES
View the document8. SANITARY APPARATUS (Fixture, Appliance)
View the document9. VENTILATION
View the document10. RAIN WATER
View the document11. MATERIALS
View the document12. PRINCIPLES OF CALCULATION
View the document13. DIMENSIONING
View the document14. INSPECTION AND TESTING

2. FIELD OF APPLICATION


These guidelines are applicable for:



- Domestic house drainage systems (soil and waste waters)



- Partly covered: Rain water pipes



2.100

PRINCIPLES


This manual covers modern methods of plumbing, namely, the single stack system, the divided stack system and the one-pipe system. However, in view of the simplicity and economy of the single stack system, it is recommended that for all new construction this system may be adopted in preference to other systems.



2.200

DESIGN CONSIDERATIONS


The system to be adopted will depend on the type and design of the building in which it is to be installed and will be one of the following:

a) Single stack system
b) Divided stack system

c) One-pipe system

2.300

STACK SYSTEMS


This is the name given to a simplified system, wherein all separate ventilation pipes are omitted. The stack itself is made to cater (or provide) for all vent requirements by restricting the flow into the stack to certain predetermined limits.


A stack is a pipeline for main vertical discharge, extending more than one storey in height, and where all fixtures connected to it require a trap.


Note: rain water pipes are not to be fitted to stacks for soil and/or waste water pipelines. Usually they are not connected to the ground pipelines but drained through separate systems.



Figure

2.310

Single Stack System (Standard Installation) - In this mixed system, the pipe conveys discharges from all waste water appliances (e.g. soil and waste appliances) such as water closets, urinals, bath tubs, wash basins, kitchen sinks, etc.).


Figure

CONNECTED DIRECTLY TO THE TOWN SEWER OR TO SEPTIC TANK OF ADEQUATE SIZE.

These pipelines convey waste water directly to the canalization main pipelines or into individual septic tanks of adequate size.

2.320

Divided Stack System (Individual Installation) - In this divided system there are two (or more) separate separate stacks:


Figure

CONNECTED SEPARATELY TO SEPTIC TANKS

i) The soil stack conveys discharges from water closets, urinals and similar soil appliances directly to the septic tank.

ii) The waste stack conveys wastes from ablutionary (washing, washing-off) and culinary appliances (food), such as wash basins, bath tubs, kitchen sinks, shower trays, etc., either to a separate septic tank, or to the last chamber of the septic tank.

Divided stacks are to be ventilated above roof level in the same way as single stacks. If required, a waste stack ventilation, instead of being led straight through the roofing, could be joined to a nearby soil stack ventilation by use of 88° to 45° bends, with the branch at least 0.5 m above the upper level of the top-most apparatus.

Note: Divided stack systems might be useful in places with individual, small septic tanks. It is not required for mixed systems, e.g. when led into the town mains, or where septic tanks of sufficient capacity are provided.

2.340

Note: Previously a “Two-Pipe System” was applied in building installations. In this separate pipelines conveyed discharges:



- The soil pipes from water closets, urinals and similar appliances discharged directly to the drainage system (e.g. septic tank). Thorough ventilation was maintained by an extensive pipe-work of additional branch and main ventilation pipes.



- The waste pipes from ablutionary and culinary appliances were conveyed to the drainage systems directly or through a trapped gully, where desired. In these pipelines also the ventilation was maintained by an extensive pipework of additional branch and main ventilation pipes.


As mentioned earlier, in view of modernization and consideration of economy this “Two-Pipe System” is not now applied in new buildings.


DIAGRAM OF TWO-PIPE SYSTEM

Main Soil Pipe (M.S.P.): A pipe connecting one or more branch soil pipes to the drain.

Main Waste Pipe (M.W.P.): A pipe connecting one or more branch waste pipes to the drain.

Main Soil Waste Pipe (M.S.W.P.): A pipe connecting one or more branch soil waste pipes to the drain.

Branch Soil Pipe (B.S.P.): A pipe connecting waste appliances to the main soil pipe, (stack).

Branch Waste Pipe (B.W.P.): A pipe connecting waste appliances to the main waste pipe, (stack)

Branch Soil Waste Pipe (B.S.W.P.): A pipe connecting soil and/or waste appliances to the main soil waste pipe (stack).

2.400 DRAINAGE REQUIREMENTS FOR BUILDINGS

Principles of system


Figure

Notes:

- Rain water drains may only be connected to combined or single sewer systems in which the sewer pipe is designed to take both sewage and rain water.

- Rain water drains must be properly trapped before entry into soil drainage system (town sewer).

- Written permission must first be obtained from the concerned government authorities befor rainwater drains can be connected to the sewerage systems.