A water filtration unit is made of uniform-size sand particles of 0.4 mm diameter witha shape factor of 0.84 and specific gravity of 2.55. The depth of the filter bed is 0.70 mand the porosity is 0.35. The filter bed is to be expanded to a porosity of 0.65 by hydraulicbackwash. If the terminal settling velocity of sand particles during backwash is 4.5 cm/s,the required backwash velocity is

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the required backwash velocity is

Fundamentals of Geotechnical Engineering (MindTap Course List)

5th Edition

ISBN:9781305635180

Author:Braja M. Das, Nagaratnam Sivakugan

Publisher:Braja M. Das, Nagaratnam Sivakugan

Chapter6: Hydraulic Conductivity

Section: Chapter Questions

Problem 6.7P

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The storm drains system transports rainwater or stormwater and other runoff from roads, parking lots, and roof downpipes directly to nearby creeks, rivers, or the sea without any treatment.

Question

A water filtration unit is made of uniform-size sand particles of 0.4 mm diameter with
a shape factor of 0.84 and specific gravity of 2.55. The depth of the filter bed is 0.70 m
and the porosity is 0.35. The filter bed is to be expanded to a porosity of 0.65 by hydraulic
backwash. If the terminal settling velocity of sand particles during backwash is 4.5 cm/s,
the required backwash velocity is

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