GROUND WATER IN NORTH-CENTRAL TENNESSEE
GROUND WATER IN NORTH-CENTRAL TENNESSEE
GROUND WATER IN NORTH-CENTRAL TENNESSEE
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<strong>GROUND</strong> <strong>WATER</strong> <strong>IN</strong> <strong>NORTH</strong>-<strong>CENTRAL</strong> <strong>TENNESSEE</strong><br />
generally encounter concentrated salt water in the Ordovician rocks,<br />
from which brine was formerly pumped and evaporated to obtain<br />
salt for household use. In some wells the salty water contains a<br />
small amount of oil. In the hilly area southeast of Cotton town<br />
drilled wells encounter but little water, and that is inferior in quality<br />
and is associated with natural gas; hence it is in some places difficult<br />
or impossible to develop adequate household water supplies. Unfor<br />
tunately, strata bearing fresh water are not likely to occur below<br />
those from which the salty and oil-bearing waters are obtained.<br />
In the rolling country of the Nashville Basin, which constitutes the<br />
southernmost part of the county, ground-water conditions differ so<br />
greatly from place to place that it is impossible to predict the depth<br />
and water-yielding capacity of the permeable zones. In the inter-<br />
stream tracts many domestic water supplies are derived from drilled<br />
wells, most of which are between 25 and 50 feet deep. However, not<br />
all such wells obtain adequate supplies, and some are dry. Neither is<br />
this shallow ground water satisfactory in chemical character at all<br />
places, for it is generally high in noncarbonate hardness and may con<br />
tain an appreciable quantity of hydrogen sulphide. Analyses 131 and<br />
132 (pp. 112-113) are representative. In a few places the water is ex<br />
tremely concentrated in sulphate, chloride, and hydrogen sulphide, like<br />
that from Castalian Spring (analysis 137), and is quite unfit for all or<br />
dinary uses. Seemingly the earthy Middle Ordovician limestones that<br />
occupy much of this area have never been extensively channeled, and<br />
such permeable rocks as exist have been largely drained by the<br />
tributaries of the Cumberland River. Several relatively deep wells<br />
in Gallatin, such as Nos. 134, 135, and 136, reach a water-bearing<br />
zone from 124 to about 200 feet below the surface, at approximately<br />
the same altitude as the Cumberland River. The tested capacity of<br />
these wells, which is reported as 80 to 150 gallons a minute, is much<br />
greater than the capacity of any other known wells within the county.<br />
Furthermore, the water is only moderately concentrated, has only a<br />
very little noncarbonate hardness, and is suitable for all ordinary<br />
purposes if softened. Within the meander belt of the Cumberland<br />
River along the southern edge of the county the limestone is extremely<br />
cavernous and contains many sink holes into which the water is<br />
reported to rise from below when the river is in flood, the water level<br />
fluctuating with the stage of the river. Hence there are in this area<br />
systems of solution channels adjusted to the level of the river in its<br />
present erosion cycle, and it is possible that the deep wells at Gallatin<br />
tap a channeled zone that is tributary to one of these systems. If<br />
such is the case, it may be that ground water of satisfactory chemical<br />
character can be obtained at many other places south of the Highland<br />
Rim escarpment by drilling to or slightly below the level of the<br />
Cumberland River. However, no other wells as deep as those at