Drainage System And Its Significance
Drainage is the disposal of excess water on land (either used or in type of storm water). It must be distinguished from flood management which is the prevention of damage because of overflow from river. There are two type of system adopted for waste water collection. Separate sanitary and mixed system. In separate sanitary system, there is a separate sewer that collects the household, commercial and industrial waste water and disposes them while a separate sewer collects the storm water and disposes it separately. In the mixed system, each the storm water and domestic water are conveyed by way of the same pipe network.
Sanitary sewers ought to have a self cleansing velocity of (.6-1
m/s). This self cleansing velocity is achieved by laying the drain on a steep slope. Manholes ought to be positioned at interval of a hundred-120m for the purpose of maintaining and servicing of the sewer. It should be noted that waste water within the sewer are usually transported by gravitational force slightly than mechanical means (pumping) for convenient sake. This is why in laying sewer pipes; the topography of the world needs to be well understood.
The storm water flow can be estimated by .278CIA where C is the coefficient of runoff, I is the rainfall intensity and A is the catchment area. C is usually obtained from table which is a operate of factors that affect infiltration. From rainfall data I will be estimated.
A might be estimated through the use of planimeter or superimposing scaled grid paper on the map and note the grid that fall within the boundary of the map . The waste water from trade, commercial centers and domestic makes use of are normally estimated by knowing the quantity of waste water the customers' discharges by using questionnaire and personal interview. The inhabitants of individuals and number of industries must be noted for this estimation.
The overall steps in format sewers include:
Establish complete map of the world including road contour, topography and utilities
Drains are shown with a single line with arrows for direction
Manholes are shown with a dot at all its essential places because the junctions and its intermediate level of a hundred-120m interval
Sewers are design to follow natural topography
Sewers are principally branch network
Sewers or drains are often located along the road
Design approach for sewers is as follows;
Estimate manning fixed and choose slope
Compute the section factor
Get the best hydraulic part either rectangle or trapezoid
Check the satisfaction of minimum velocity
Addition of adequate freeboard to avoid overflowing
The disposal of the waste water may very well be handled or not treated. Nevertheless, the remedy is normally by biological method. The disposal of waste water is of immerse necessary for economic growth. The treated or untreated waste might be used as a source of irrigation, complement stream or river flow and could be used as a supply of recharge for ground water.
It is obvious within the cities of the developing countries that the most of construction industries don't take note of all of the above talked about process. In consequence storm water follows drains that are not specified for them or overflows the drains there by causing erosions. However, some of the storm water are stagnant in the drains there by turning into a breeding place for mosquitoes and toads. This might end in enhance of malaria and water related disease in the vicinity. All this is because; most authorities in such cities have not yet understand the important of drainage systems and the role it plays in social- financial development.
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