GROUND WATER IN NORTH-CENTRAL TENNESSEE

DICKSON COUNTY 148
mineral matter, whereas No. 191 yields a calcium sulphate water
which is so hard and so highly concentrated as to be unfit for ordinary
uses.
MUNICIPAL GROUND-WATER SUPPIJDES
Dickson. The municipal water supply of Dickson, the largest town of the
county, is derived from two springs near the head of the East Fork of the Piney
River. The collecting and distributing works are the property of the town. The
upper spring, which is known as Payne Spring No. 1 (No. 224, p. 147), is about a
mile northwest of the town and constitutes the perennial head of the East Fork.
It is a seepage spring supplied by underflow in chert gravel and sand, and its
catchment area comprises about 185 acres of timbered land and 15 acres of tilled
ground. The improved orifice is a concrete-walled pit about 20 by 25 feet in plan,
sunk to the water-bearing gravel and roofed over. The yield varies with the sea­
sons, but the estimated minimum is about 50 gallons a minute. This spring,
about 765 feet above sea level, discharges by gravity into a 404,000-gallon reser­
voir about 20 feet lower. The second spring, known as Baker Cave Spring (No.
225), is a tubular spring that issues from limestone in the west bank of the East
Fork about 300 yards south of the Centerville and Dickson pike and about a
mile southwest of Dickson. The orifice is about 700 feet abpve sea level. The
maximum and minimum discharge of the spring are not known, although it is
reported that the minimum yield exceeds the present draft, which is approximately
85 gallons a minute. The water from this spring is raised to the reservoir by a
3-stage centrifugal pump having a rated capacity of 250 gallons a minute. From
the reservoir the water is pumped directly into the distributing mains by high-
pressure pumps, including one single-stage centrifugal pump with a capacity of 300
gallons a minute, a similar pump with a capacity of 600 gallons a minute, and a
2-stage centrifugal fire pump with a capacity of 750 gallons a minute. All the
pumps are operated by electric motors. The chemical character of the water
from Baker Cave Spring is shown by analysis 225 (pp. 114-115). The approxi­
mate temperature of the water is 56° F.