FLORIDA GEOLOGICAL SURVEY


be predicted on the basis of data collected elsewhere. Figure 39 illus-
trates how water levels are affected in the vicinity of a pumped well
near the Chemstrand plant. This figure shows theoretical drawdowns in
the vicinity of a well pumped at the rate of 700 gpm (about 1 mgd)
from an aquifer having a transmissibility coefficient of 150,000 gpd per
foot and a storage coefficient of 0.15. As the drawdowns outside the
pumped well vary directly with discharge, drawdowns for greater or


DISTANCE. IN FEET. FROM PUMPED WELL
 100 1,000

 ------ I 7


S.. .. .... Computed on the bosis of:
 ST rSO150,000 gpd/ft
 ;0 '5 015
 Q 700 gpm i
 Note Compulolaons based on pumpig from storage from on
 1Logqufer of lorge orel extent

 Figure 39. Graph showing theoretical drawdowns in the vicinity of a well.

lesser rates of discharge may be computed from these curves. For ex-
ample. as shown in figure 39, under the assumed conditions, the draw-
down 100 feet from a well discharging at 700 gpm would be 4.3 feet after
100 days of pumping. If the well had discharged 2,100 gpm for the same
length of time, the drawdown at the same distance would have been
three times as much, or 12.9 feet.

 MINERAL CONTENT
 THE SAND-AND-GRAVEL AQUIFER
 The sand-and-gravel aquifer is the major source of ground water used
in Escambia and Santa Rosa counties. Differences in the composition of
the aquifer affect the chemical quality of the water. In some areas clay