Graded Filter

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Filter, Graded

 

a device in headworks that consists of several layers of unconsolidated material with increasingly coarse particles in each layer. The material may be sand, gravel, rubble, or pebbles; the coarseness of the particles increases toward the seepage line. Graded filters are used mainly in earth dams and other hydraulic-engineering installations erected on soft foundations. Such filters prevent seepage from washing fine soil particles from the body and base of the installation.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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Once dosed, effluent passes through 6 inches of rock and 2 feet of graded filter sand before being collected by three 1,200 gallon pump tanks connected to form one 3,600-gallon pump chamber.
By merging and processing 16 exposures, 4 shot by Jonathan Kern using radial graded filters and 12 unfiltered images that she herself took, Wendy Carlos (www.wendycarlos.com/eclipse.html) created a view of totality that faithfully reproduces how the eclipsed Sun actually appeared in the sky over her observing site at the Barn Motel in Lusaka, Zambia.