Science of Water : Concepts and Applications

72 The Science of Water: Concepts and Applications
BASIC PUMPING HYDRAULICS
Water, regardless of the source, is conveyed to the waterworks for treatment and distributed to the
users. Conveyance from the source to the point of treatment occurs by aqueducts, pipelines, or open
channels, but the treated water is normally distributed in pressurized closed conduits. After use,
whatever the purpose, the water becomes wastewater, which must be disposed of somehow, but
almost always ends up being conveyed back to a treatment facility before being outfalled to some
water body, to begin the cycle again.
We call this an urban water cycle, because it provides a human-generated imitation of the natural
water cycle. Unlike the natural water cycle, however, without pipes, the cycle would be nonexistent
or, at least, short-circuited.
PIPING
TABLE 3.3
C Factors
Type of Pipe C Factor
Asbestos cement 140
Brass 140
Brick sewer 100
Cast iron
10 years old
20 years old
For use as water mains in a distribution system, pipes must be strong and durable in order to resist
applied forces and corrosion. The pipe is subjected to internal pressure from the water and to external
pressure from the weight of the backfi ll (soil) and vehicles above it. The pipe may also have to
withstand water hammer. Damage due to corrosion or rusting may also occur internally because of
the water quality or externally because of the nature of the soil conditions.
110
90
Ductile iron (cement lined) 140
Concrete or concrete lined
Smooth, steel forms
Wooden forms
Rough
140
120
110
Copper 140
Fire hose (rubber lined) 135
Galvanized iron 120
Glass 140
Lead 130
Masonry conduit 130
Plastic 150
Steel
Coal-tar enamel lined
New unlined
Riveted
150
140
110
Tin 130
Vitrifi ed 120
Wood stave 120
Source: Adapted from Lindeburg, M.R., Civil Engineering Reference Manual,
Professional Publications, Inc., San Carlos, CA, 1986.