FLOOD07651

• County: Statewide
• Basin: Statewide
• Title: Groundwater Pumping Tests: Design and Analysis
• Date: 12/1/1997
• Floodplain - Doc Type: Educational/Technical/Reference Information

102 GROUNDWATER PUMPING TESTS

CASE STUDIES 103

.'

Table 5.8. Database for Case Study 5.8

Distance Adjusted Drawdown
(ft) (ft)

28 1.68
85 1.22
230 .83
420 .56

2.0

C,., = (0.72/0.27 - 1.59/0.62)/(0.62 + 0.27)
C,., = 0.11 sec'/ft'

I.S
.....
u..
c 1.0
.
0
"0
.
0
L
Cl O. S

The average value of the well loss coefficient is 0.08 sec'l
ft'. Well loss at the 1400 gpm rate was calculated to be 0.77
ft and amounted to about 10% of the total drawdown in the
production well.

0.0
10

100

1000

INDUCED STREAMBED INFILTRATION

Distance eFt>
Figure 5.9. Distance-drawdown graph for Case Study 5.8.

A pumping test was conducted in Case Study 5.8 on
February 20-23, 1956, using a group of six wells located
along the Mad River about 4 miles northwest of the city of
Springfield, Ohio (see Walton, 1963). Wells were located
400 ft west of Mad River. Observation wells were located
28, 85, 230, and 420 ft north from a production well. Logs of
wells and test holes indicate that the 100-ft-thick aquifer
consists of coarse sand and gravel, is about 4000 ft wide,
and trends southwest to northeast through the pumping
test site. The constant pumping rate was 1034 gpm and the
test duration was 4310 minutes. Distance-drawdown data
for observation wells at the end of the test when steady
state conditions prevailed are presented in Table 5.8.
A straight line was drawn through the semilogarithmic
distance-drawdown graph and aquifer transmissivity was
calculated to be 547,000 gpdift. The recharging image well
simulating induced streambed infiltration was located at a
distance of 1372 ft from the production well. Aquifer

specific yield is 0.01 and depletion of streamflow at the end
of the test was 960 gpm or about 93% of the discharge rate.
The reach of the streambed within the area of influence of
pumping was calculated to be 8000 ft and the average
width of the streambed is 82 ft. The streambed area of
induced infiltration is 656,000 square ft. The induced
infiltration rate is 9.2 X 10' gpdiacre. The average
drawdown beneath the streambed was calculated to be 0.09
ft. The induced infiltration rate per ft of head loss is 1.0 X
10' gpd/acre/ft at a surface water temperature of 390F. The
streambed induced infiltration rate is in the clogged slow
sand filter category (see Walton, 1970, p. 266). Well storage
capacity and delayed gravity yield impacts were negligible
at the end of the test. Calculations are as follows:

Q = 1034 gpm,
T = 52811034)/1.0

s, = 1.0 ft
T = 545,952 gpd/ft

The distance.drawdown graph is presented in Figure 5.9.