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1.8 Transmission Works 17

3
2
(c) Surface area A V>H (1,576 m )>(3.05 m – 0.61 m) 646 m (such as 10.7 m by
61 m).
2
2
(d) Surface rating SR Q>A (26,268 L/min)>(646 m ) 40.7 L/min/m .
4. Six rapid sand filters.
2
(a) Assumed rating SR Q>A 122.1 L/min/m ; number of filters N 6.
2
(b) Area A Q>(N SR) (26,268 L/min)>(6 122.1) 35.86 m (such as 4.6 m by
7.9 m).

1.8 TRANSMISSION WORKS

Supply conduits, or aqueducts, transport water from the source of supply to the commu-
nity and so form the connecting link between collection works and distribution systems.
Source location determines whether conduits are short or long, and whether transport is
by gravity or pumping. Depending on topography and available materials, conduits are
designed for open-channel or pressure flow. They may follow the hydraulic grade line
as canals dug through the ground, flumes elevated above the ground, grade aqueducts
laid in balanced cut and cover at the ground surface, and grade tunnels penetrating hills;
or they may depart from the hydraulic grade line as pressure aqueducts laid in balanced
cut and cover at the ground surface, pressure tunnels dipping beneath valleys or hills,
and pipelines of fabricated materials following the ground surface, if necessary over
hill and through dale, sometimes even rising above the hydraulic grade line. The 336
mile (541 km) long Central Arizona Project aqueduct shown in Fig. 1.6 is the largest

Figure 1.6 Central Arizona Project
Aqueduct
Source: Wikipedia http://en.
wikipedia.org/wiki/Image:
Arizona_cap_ canal.jpg