GROUND WATER IN NORTH-CENTRAL TENNESSEE

224 GEOUND WATEK IN. NORTH-CENTRAL TENNESSEE
Lebanon, all of which tap a common water-bearing bed. Wells 333
and 334 (Nos. 1 and 2, respectively, city of Lebanon) are 205 and
196 feet deep and 10 and 8 inches in diameter. They are about 75
yards east of the Lebanon station of the Tennessee Central Railroad.
Both of these wells obtain water from the Eidley (?) limestone about
185 feet below the surface (about 345 feet above sea level); the static
level in the wet months is 64 feet below the surface (about 465 feet
above sea level), or about 25 feet below the near-by Sinking Creek.
Presumably the water was obtained in solution channels. Well 335
(No. 3, city of Lebanon), which was originally about 200 feet deep,
was deepened to 351 feet in 1924 without finding any water-bearing
beds below that which is about 185 feet below the surface. These
wells are pumped by air lifts. Two of the three wells are generally
operated 10 hours or more each day, and the yield of each ranges
from about 100 to more than 200 gallons a minute, varying with the
season; The specific capacity is relatively large for north-central
Tennessee and ranges between 5 and 10 gallons a minute for each foot
of drawdown. In 1927 wells 334 and 335 were pumped steadily from
September 16 until October 12, and the combined yield decreased
gradually in that period from 325 to 200 gallons a minute. About
8 a. m. October 12, about 10 hours after the start of a long heavy
rain on the adjacent region, the yield began to increase, and on October
13 it reached a maximum of about 450 gallons a minute. Most of
the increase in yield was probably due to rise in static level of the
ground water in response to the rainfall, although a part of it may have
been due to greater efficiency of the air-lift pumps as their submer­
gence increased with rising static level. Furthermore, it is reported
that the discharge from well 335 is slightly turbid after rainfall in the
vicinity, even though it is cased from the surface to the water-bearing
bed. If this report is correct it follows that the changes in static
level induced by rainfall are not merely hydrostatic effects but represent
actual saturation, of permeable rock. Furthermore, as the
changes take place so promptly after rainfall, the water-bearing bed
tapped by the municipal wells must communicate rather directly
with the surface by solution channels or other openings which can
transmit water rapidly. Well 336, which is owned by the Interstate
Ice &
Coal Co., derives most of its water from an open channel or
cellular zone of the limestone about 18 inches thick and about 185
feet ]>elow the surface. Another water-bearing bed was penetrated
at a depth of 85 feet, but none was found below the 185-foot bed,
although the well is 304 feet deep. Like the Lebanon municipal wells,
weH 3 36 is pumped by an air lift whose capacity is about 150 gallons
a minute. It also interferes with the municipal wells, whose yield is
reported to drop 50 or 75 gallons a minute within 15 minutes after
the piunp oa well 336 is started. The two wells (No. 347) that con*