Ground-water development in East St. Louis area, Illinois. Urbana, IL ...

in which the well is operated during three successive
and equal time periods at constant fractions of full capacity.
Step-drawdown test data are available for nine wells
in the East St. Louis area. The results of the step-drawdown
tests and construction features of the wells tested
are given in table 14. Well-loss constants for wells
tested immediately after construction range from 0.2
to 1.0 sec 2 /ft 5 .
Specific-capacity data collected during well-production
tests made on 32 industrial, municipal, and irrigation
wells are given in table 15. The well-production tests
consisted of pumping a well at a constant rate and frequently
measuring the drawdown in the pumped well.
Drawdowns were commonly measured with an airline,
electric dropline, or steel tape; rates of pumping were
largely measured by means of a circular orifice at the end
of the pump discharge pipe.
The lengths of tests ranged from 11 minutes to 2
days; pumping rates ranged from 104 to 1905 gpm.
Screen diameters ranged from 8 to 32 inches.
Specific-capacity data for 65 selected relief wells are
given in table 16. The wells were tested during the period
1952 through 1960 by the U.S. Corps of Engineers.
The saturated thickness of the aquifer at well sites was
estimated from logs of wells and water-level data. The
tests consisted of pumping the wells at a constant rate of
500 gpm for 2 hours and frequently measuring the drawdown
in the pumped well.
A coefficient of storage in the water-table range
(0.10) estimated from aquifer-test data and several
values of t and r w were used (see Walton 1962) to determine
the relationship between specific capacity and
the coefficient of transmissibility for various values of
r w 2 /t (figure 22). Specific capacities, data concerning
the lengths of tests and radii of wells in tables 15 and
16, and figure 23 were used to estimate theoretical coefficients
of transmissibility of the aquifer within the
cones of depression of production wells. Theoretical
coefficients of permeability within the cones of depression
were estimated by dividing the coefficient of transmissibility
by the average saturated thickness of the
aquifer within cones of depression The average saturated
thickness of the aquifer within cones of depression
was estimated from logs of wells and water-level data.
No great accuracy is implied for the coefficients of
permeabilities estimated from specific-capacity data because
they are based on an estimated coefficient of storage
and are not corrected for well-loss and partial penetration
losses. However, as shown in table 14, well-loss
constants for most newly constructed wells are small.
Most wells penetrate completely the more permeable parts
of the aquifer. Thus, well and partial penetration losses
were probably small and not significant. The data in
tables 15 and 16 can be considered only rough approximations
of the coefficient of permeability of the aquifer.
However, the coefficients of permeability in the Monsanto
area estimated from specific-capacity data agree
closely with the coefficients of permeability computed
from aquifer tests at the Mobil Oil Refinery and the Monsanto
Chemical Corporation, indicating that the estimated
coefficients of permeability are meaningful.
Water-level and pumpage data for existing pumping
centers were used to compute pumping center specific
capacities given in table 17. Pumping center specific capacity
is here defined as the total pumpage from wells
within the pumping center per foot of average drawdown
within the pumping center.
Summary of Aquifer-Test Data
A map showing how the coefficient of permeability
varies within the East St. Louis area (figure 23) was
Owner
Mobil Oil Co.
Screen
length
Driller
(ft)
Luhr Bros. 36
Table 14. Results of Step-■Drawdown Tests
Screen
diameter
fin)
16
Screen Material
Johnson Everdur
No. 50 slot
Date
well
drilled
12/59
Date
of
test
Well-loss
constant
(sec 2 /ft 5 )
10/61 2.0
Southwestern Layne-Western 20 10 Slotted pipe 11/60 12/60 0.2
Campus of SIU,
Edwardsville
Collinsville (V) Layne-Western 30 16 Layne No. 4 slot 8/50 8/50 0.7
Thomason Thorpe 32 X 40 Porous concrete 5/54 5/54 0.2
Amos Bonham Thorpe 30 X 40 Porous concrete 10/54 4/55 0.45
Herbert Bischoff Thorpe 60 30 X 40 Porous concrete 1/54 5/54 0.5
V. W. Eckmann Thorpe 48 30 X 40 Porous concrete 9/54 10/54 1.0
East St. Louis Luhr Bros. Wood 4/55 5/55 1.0
Drainage Dist.
East St. Louis Luhr Bros. Wood 4/55 5/55 1.0
Drainage Dist.
22