GROUND WATER IN NORTH-CENTRAL TENNESSEE

WIIJSON COUNTY 227
associated with the more permeable strata 200 feet or less below the
surface, is generally satisfactory for most purposes. Those repre­
sented by analyses 328,330,333,347, and 348 (pp. 116-117) are typical.
These are moderately concentrated calcium bicarbonate waters that
have moderate carbonate hardness and some noncarbonate hardness,
so that they are somewhat objectionable as scale formers and soap
consumers unless softened. The waters of this type that are asso­
ciated with the deeper beds are usually higher in noncarbonate hard­
ness. Some, such as No. 353, are much too hard for satisfactory use
in laundering or as boiler feed water and even if softened are likely to
be unsuitable for certain purposes. In contrast with waters of this
type are the highly concentrated sulphate and chloride waters, of
which analyses 326,344, and 352 are representative. They may occur
at slight depth in such thin-bedded and shaly formations as the Her­
mitage formation and Lebanon limestone or at moderate depth in
any of the rock formations, especially in the hilly areas and the contig­
uous parts of the peneplain in the southeastern quadrant of the coun­
ty. These are the areas in which underground drainage has not been
completely established in the present erosion cycle. The sulphate and
chloride waters are of two general classes those, such as No. 344,
which contain much more sodium than other bases and hence are
moderately soft unless very highly concentrated and those which
contain large amounts of calcium and magnesium and have much
noncarbonate hardness. The waters of the first class may be used
for domestic and some other purposes if they do not contain much
more than 1,000 parts per million of dissolved mineral matter, although
they are somewhat objectionable. Those of the second class are
generally unfit for any ordinary use. A considerable proportion of
the sulphate and chloride waters contain appreciable amounts of
hydrogen sulphide and objectionable amounts of iron, which, in the
presence of air, form a suspended precipitate of black ferrous sulphide.
In the vicinity of Norene and possibly elsewhere in the southeastern
quadrant of the county some of the ground water contains moderate
quantities of hydrocarbon gases. It is reported that for about two
years gas issued from one well in Norene, about 60 feet deep, in suffi­
cient quantity to illuminate a store. The water from well 352 (pp. 230-
232) is unusual in that most of the combined sulphur occurs as the hy-
drosulphide radicle (HS). In general, highly concentrated waters of
these types are likely to be found in any part of the county in beds
more than 100 feet below the surface and, so far as is known, in all
beds much more than 200 feet below the surface. Furthermore, it
is not known that potable ground water exists at any place in beds
underlying those which contain the highly concentrated sulphate or
chlorid.6 water.