GROUND WATER IN NORTH-CENTRAL TENNESSEE

108 GROUND WATER IN NORTH-CENTRAL TENNESSEE
Many springs and wells that issue from tubular solution channels
in the limestone of north-central Tennessee at times discharge turbid
water containing much suspended clay and silt. This suspended
matter is derived from soil and rock waste that is carried through
sink holes into the underground drainage system, so that the under­
ground streams, like surface streams, carry more suspended matter
after periods of heavy precipitation and vigorous run-off. The
amount of suspended matter in the water, the duration of the periods
of high turbidity, and the lag between precipitation and increase of
turbidity may vary greatly and are generally very different at different
springs. The regimen of any spring can not be known even approxi­
mately unless its load of suspended matter is determined systemati­
cally at different rates of discharge and over a long period.
Suspended matter in a water may not be deleterious for some uses,
but it must be thoroughly removed to make the water satisfactory for
a municipal supply or for most industrial purposes. Many of the
tubular springs of north-central Tennessee offer difficult problems in
the removal of suspended matter to adapt them to use. In order to-
be successful, a clarifying plant must have a large overload capacity
to care for periods when the turbidity of the water is high .
SANITARY CONSIDERATIONS
The analyses of the representative ground waters and the statements
that have been made in regard to the suitability of the waters for
domestic use consider only the effects of the dissolved mineral constit­
uents. They do not consider the presence or absence of disease-
bearing bacteria, which is generally the critical factor in determining
the suitability of a public supply. The number of bacteria in the
water from a given source is not likely to be constant, so that a single
determination of the sanitary character of a water may be grossly
misleading.
Scrupulous care should be exercised to protect each well and spring
used for domestic supply from pollution by organic waste carried by
surface drainage, by seepage through the soil, by stock, or on the shoes
and clothing of people. Every well should be so located as not to
receive drainage from the vicinity of any building, sewer, cesspool, or
privy and should be tightly closed at the top in a sanitary manner.
Springs should be surrounded by sturdy stock barricades and pro­
tected from surface drainage by suitable dikes, cut-off walls, or other
structures. In a region underlain by limestone, such as north-
central Tennessee, ground water that is circulating in solution chan­
nels may be polluted over extensive areas. Hence the sanitary char­
acter of the water from all tubular springs and wells that enter solu­
tion channels is subject to distrust unless it is shown to be free from.