LAND DRAINAGE BY MEANS OF PUMPS. 43 
tractors often have underbid others who have become familiar with 
foundation construction under such circumstances, and the former 
have been awarded the contract. However, such bids often prove 
to be the highest, because of delays, unsatisfactory results, and even 
forfeiture of contract. Often the expense of foundation is a large 
part of the cost of the completed plant. When properly constructed 
it is the most permanent part of the plant, and should outlast the 
building and serve as the support for several sets of machinery. 
ARRANGEMENT OF SUCTION AND DISCHARGE PIPING. 
Proper arrangement of the suction and discharge pipes is essential 
to the economical and reliable operation of the plant. The pipes 
should be as direct as possible. All bends should be of long radius, 
and the interior of the pipes should be as smooth as practicable, 
in order that the lost work, due to friction, may be small. Since 
the head Consumed in overcoming friction varies as the square of 
the velocity, the larger the piping the less the friction loss. The 
piping should be made large enough to reduce the velocity in the 
pipe to as near 5 feet per second as practicable. All changes in size 
and direction of the piping should be gradual, and at no point should 
the water be permitted to flow around a sharp corner. 
The suction pit should be carried to a greater depth than the main 
canal, even though this results in some danger of excessive seepage 
and of opening springs or boils through the lower layers from the 
river when the suction pit is close to the river bank. This has been 
a frequent source of difficulty in pumping plants, and on this account 
the discharge pipe should be made longer than it often is. The sides 
of the suction pit should be protected by a reinforced-concrete wall 
supported by round piling, and usually a cut-off wall of sheet piling 
should be driven along the center lines of these side walls. If the 
material in the bottom of the pit is inclined toward quicksand, or if 
there are springs and boils, the bottom as well as the sides of the pit 
should be of reinforced concrete well tied down by the use of round 
and sheet piling, as it must be remembered that there will be an up- 
ward pressure on the bottom of the pit when the water is lowered. 
The pit should be shaped to form a suitable gradually-curved entrance 
to the suction pipe, and should be provided at its outer end with a 
steel screen. The screen openings should be of such size that the 
velocity through them, under normal conditions, would not be more 
than 1 foot per second. 
In order that the suction lift may be kept low, the pump should be 
set as low as is consistent with securing good foundation, ease of 
installation, and safety after installation. In general, the plant 
should be at such an elevation as would make it very unlikely that 
excessive rainfall or suspension of pumping would cause the water 
