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Drainage gradient (DG) is a term in road design, defined as the combined slope due to road surface cross slope (CS) and longitudinal slope (hilliness). Although the term may not be used, the concept is also used in roof design and landscape architecture. If the drainage gradient is too low, rain and melt water drainage will be insufficient.
Cross slope, cross fall or camber is a geometric feature of pavement surfaces: the transverse slope with respect to the horizon. It is a very important safety factor. Cross slope is provided to provide a drainage gradient so that water will run off the surface to a drainage system such as a street gutter or ditch.
The Industrial Revolution increased population density in manufacturing districts, and produced pipes useful for drain-waste-vent systems from buildings to sewers. Gravity sewers have been assembled from cast iron pipe , vitrified clay pipe , precast concrete pipe, asbestos-cement pipe, and plastic pipe . [ 8 ]
Combined sewer outflow into the Anacostia River in Washington, D.C. Ratcliff Beach CSO discharges into the River Thames in London [7]. These relief structures, called "storm-water regulators" (in American English - or "combined sewer overflows" in British English) are constructed in combined sewer systems to divert flows in excess of the peak design flow of the sewage treatment plant. [6]
For such drainage systems to work properly it is crucial that neutral air pressure be maintained within all pipes, allowing free gravity flow of water and sewage through drains. It is critical that a sufficient fall gradient (downward slope) be maintained throughout the drain pipes to keep liquids and entrained solids flowing freely from a ...
Effluent sewer systems, also called septic tank effluent drainage (STED) or solids-free sewer (SFS) systems, have septic tanks that collect sewage from residences and businesses, and the effluent that comes out of the tank is sent to either a centralized sewage treatment plant or a distributed treatment system for further treatment. Most of the ...
the design drain spacing (L) can be found from the equation in dependence of the drain depth (Dd) and drain radius (r). Drainage criteria One would not want the water table to be too shallow to avoid crop yield depression nor too deep to avoid drought conditions. This is a subject of drainage research.
England sets maximum spacing at 90 metres (300 ft). The only exception is for sewers with diameters larger than human heights. Those can have spacing up to 200 metres (660 ft). [10] Maximum spacing of 100 metres (330 ft) is used in Scotland. [11] The 120-metre (390 ft) requirement is used in Brazil, [12] and 150-metre (490 ft) in South Africa. [13]