exhausting, passing between rollers, acid flotation, or dissolved-air flotation with or
without heat. It involves reducing from a liquid to a semi-dry condition capable of being
shoveled other than merely changing the density of the liquid (concentration) on the
one hand or drying (as in a kiln) on the other.
Sluice Gate. A gate, used for sluicing, constructed to slide vertically and fastened into
or against the masonry of dams, tanks, or other structures.
Slurry. A suspension of small undissolved particles in a very high concentration.
Softening, Water. The process of removing from water certain mineral substances
which produce a condition called hardness. There are two softening processes in
general use: chemical precipitation and the zeolite ion-exchange process.
Solids-Contact Process. The name given to the process of chemical mixing,
coagulation, flocculation, and sedimentation when carried on in a single tank in such a
manner that the mixed chemicals are introduced into a zone already precipitated floc
which serve as nuclei for further floc formation.
Solution. A gas, liquid, or solid dispersed homogeneously in a gas, liquid, or solid.
Solution Feeder. A feeder for dispensing a chemical or other material in the liquid or
dissolved state to water at a rate controlled manually or automatically the quantity of
flow. The constant rate is usually volumetric.
Sparger. An air diffuser designed to give large bubbles, used singly or in combination
with mechanical aeration devices.
Specific Capacity. The rate at which water may be drawn from a formation through a
well, to cause a drawdown of a stipulated depth. The usually units of measurement are
gallons per minute per foot and liters per minute per meter.
Specific Gravity. Ratio of weight of a unit volume of a substance to an equal volume or
water under standard conditions.
Spillway. A waterway in or about a dam or other hydraulic structure, for the escape of
Spring. A surface feature where water issues from a rock or soil onto the land or into a
body of water, the place of issuance being relatively restricted in size. Springs are
classified in accordance with many criteria, including character of water, geologic
formation, geographical location, etc.