Water and Wastewater Engineering
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WELLS 4-43
4-3. Determine the transmissivity of a confined aquifer that yields the following results
from a pumping test of a 0.46 m diameter well that fully penetrates the aquifer.
P umping rate 0.0076 m
3
/ s
s 3.00 m in 0.10 min
s 34.0 m in 1.00 min
4-4. An aquifer yields a drawdown of 1.04 m at an observation well 96.93 m from a well
pumping at 0.0170 m
3
/ s after 80 min of pumping. The virtual time is 0.6 min and the
transmissivity is 5.39 10
3
m
2
/ s. Determine the storage coefficient.
4-5. Using the data from Problem 4-4, find the drawdown at the observation well 80 days
after pumping begins.
4-6. If the transmissivity is 2.51 10
3
m
2
/ s and the storage coefficient is 2.86 10
4
,
calculate the drawdown that will result at the end of two days of pumping a 0.50 m
diameter well at a rate of 0.0194 m
3
/ s.
4-7. Determine the storage coefficient for an artesian aquifer from the pumping test
results shown in the table below. The measurements were made at an observation
well 300.00 m away from the pumping well. The pumping rate was 0.0350 m
3
/ s.
T i me (min) Drawdown (m)
100.0 3.10
500.0 4.70
1,700.0 5.90
4-8. Rework Problem 4-7, but assume that the data were obtained at an observation well
100.0 m away from the pumping well.
4-9. Determine the storage coefficient for an artesian aquifer from the pumping test
results shown in the table below. The measurements were made at an observation
well 100.00 m away from the pumping well. The pumping rate was 0.0221 m
3
/ s.
T i me (min) Drawdown (m)
10.0 1.35
100.0 3.65
1,440.0 6.30
4-10. Rework Problem 4-9, but assume that the data were obtained at an observation well
60.0 m away from the pumping well.
4-11. Determine the storage coefficient for an artesian aquifer from the following pumping
test results on a 0.76 m diameter well that fully penetrates the aquifer. The pumping
rate was 0.00350 m
3
/ s. The drawdowns were measured in the pumping well.
T i me (min) Drawdown (m)
0.20 2.00
1.80 3.70
10.0 5.00
4-44 WATER AND WASTEWATER ENGINEERING
4-12. Two wells located 106.68 m apart are both pumping at the same time. Well A pumps
at 0.0379 m
3
/ s and well B pumps at 0.0252 m
3
/ s. The diameter of each well is 0.460
m. The transmissivity is 4.35 10
3
m
2
/ s and the storage coefficient is 4.1 10
5
.
What is the interference of well A on well B after 365 days of pumping? Report your
answer to two decimal places.
4-13. Using the data from Problem 4-12, find the total drawdown in well B after 365 days
of pumping. Report your answer to two decimal places.
4-14. If two wells, no. 12 and no. 13, located 100.0 m apart, are pumping at rates of
0.0250 m
3
/ s and 0.0300 m
3
/ s, respectively, what is the interference of well no. 12 on
well no. 13 after 280 days of pumping? The diameter of each well is 0.500 m. The
transmissivity is 1.766 10
3
m
2
/ s and the storage coefficient is 6.675 10
5
.
Report your answer to two decimal places.
4-15. Using the data from Problem 4-14, find the total drawdown in well 13 after 280 days
of pumping. Report your answer to two decimal places.
4-16. Wells X, Y, and Z are located equidistant at 100.0 m intervals. Their pumping rates
are 0.0315 m
3
/ s, 0.0177 m
3
/ s, and 0.0252 m
3
/ s respectively. The diameter of each
well is 0.300 m. The transmissivity is 1.77 10
3
m
2
/ s. The storage coefficient is
6.436 10
5
. What is the interference of well X on well Y and on well Z after 100
days of pumping? Report your answer to two decimal places.
4-17. Using the data in Problem 4-16, find the total drawdown in well X at the end of 100
days of pumping. Report your answer to two decimal places.
4-18. For the well field layout shown in Figure P-4-18 , determine the effect of adding
a six
th well. Is there any potential for adverse effects on the well or the aquifer?
Assume all the wells are pumped for 100 days and that each well is 0.300 m in
diameter. Well data are given in the table below. Aquifer data are shown below the
well field data.
Knotquite Well Field No. 1
Well no. Pumping rate (m
3
/ s) Depth of well (m)
1 0.0221 111.0
2 0 . 0 315 112.0
3 0.0189 110.0
4 0.0177 111.0
5 0.0284 112.0
6 (proposed) 0.0252 111.0
The aquifer characteristics are as follows:
Storage coefficient 6.418 10
5
Transmissivity 1.761 10
3
m
2
/ s
Nonpumping water level 6.90 m below grade
Depth to top of artesian aquifer 87.0 m
WELLS 4-45
4-19. For the well field layout shown in Figure P-4-19 on page 4-46, determine the effect
of adding a sixth well. Is there any potential for adverse effects on the well or the
aquifer? Assume all the wells are pumped for 100 days and that each well is 0.300 m
in diameter. Aquifer data are shown below the well field data.
Fair Well Field No. 2
Well no. Pumping rate (m
3
/ s) Depth of well (m)
1 0.020 105.7
2 0 . 0 35 112.8
3 0.020 111.2
4 0.015 108.6
5 0 . 0 30 113.3
6 (proposed) 0.025 109.7
The aquifer characteristics are as follows:
Storage coefficient 2.11 10
6
Transmissivity 4.02 10
3
m
2
/ s
Nonpumping water level 9.50 m below grade
Depth to top of artesian aquifer 50.1 m
Knotquite
1.0 km
Proposed new well
N
Knotquite
Well Field No. 1
Approved:
50 m
50 m
50 m
50 m
001
50 m
003
50 m
005
004
002
100 m100 m
FIGURE P-4-18
4-46 WATER AND WASTEWATER ENGINEERING
4-20. What pumping rate, pumping time, or combination thereof can be sustained by the
new well in Problem 4-19 if all of the well diameters are enlarged to 1.50 m?
4-21. For the well field layout shown in Figure P-4-21 on page 4-47, determine the effect
of adding a sixth well. Is there any potential for adverse effects on the well or the
aquifer? Assume all the wells are pumped for 180 days and that ea
ch well is 0.914 m
in diameter. Well data are given in the table below. Aquifer data are shown below the
well field data.
Bode Well Field No. 3
Well No. Pumping rate (m
3
/ s) Depth of well (m)
1 0.0426 169.0
2 0.0473 170.0
3 0.0426 170.0
4 0.0404 168.0
5 0.0457 170.0
6 (proposed) 0.0473 170.0
FIGURE P-4-19
300 m
300 m
300 m
300 m
300 m
300 m
4
2
1
3
5
150 m 150 m 150 m 150 m 150 m
Proposed
new well
N
Plant
1.5 km
Fair Well
Well Field No. 2
Approved:
WELLS 4-47
The aquifer characteristics are as follows:
Storage coeffi cient 2.80 10
5
Transmissivity 1.79 10
3
m
2
/ s
Nonpumping water level 7.60 m below grade
Depth to top of artesian aquifer 156.50 m
4-22. What pumping rate, pumping time, or combination thereof can be sustained by the
new well in Problem 4-21 if all of the well diameters are enlarged to 1.80 m?
The design elements required in the following problems are:
a. Demand estimate
b. Well details
(1) Number
(2) Distanc
e between wells
(3) Diameter
(5) Depth and anticipated 100-day drawdown
(6) Screen dimensions
(5) Slot size
FIGURE P-4-21
Bode Well
Proposed
new well
125 m
125 m
145 m
137.5 m
125 m
125 m
Plant
54
63
54
4
2
5
3
1
N
Well Field No. 3
Approved:
4-48 WATER AND WASTEWATER ENGINEERING
c. Well protection requirements
(1) Casing
(2) Grouting
(3) Disinfection
(4) Well house specifi cations
d. Pump details
(1) Capacity
(2) Select a candidate pump
(3) Specify the number of stages an
d NPSH
4-23. Your firm has been retained to develop plans for a well system for the village of
Waffle. Using the design elements listed above Problem 4-23 and the following data,
design the well system.
a. Population: 250
b. Demand: 570 Lpcd
c. Water is to be supplied from wells. No treatment will be provided.
d. Top of res
ervoir is 66.0 m above ground level
e. Friction losses minor losses in piping from well to top of reservoir 0.5 m
f. Water supply is to be chlorinated, but no other treatment will be provided.
TEST BORING RESULTS, WAFFLE
Bore hole no. 2 (surface elevation: 335 m)
Strata Thickness, m Depth to bottom of strata, m
Soil (Rubicon) 1.2 1.2
S a n d 1 3.1 14.3
C l a y, red 6.1 20.4
Galena dolomite 44.8 65.2
M a q uoketa shale 39.0 104.2
S o meko sand 41.9 146.1
E a u Claire shale Boring terminated at 146.1 m
An analysis of the water indicates that it is not corrosive.
Grain size analysis of Someko sand
U.S. sieve no. Wt. % retained
8 2
1 2 1
1 6 2
2 0 1 5
30 35
4 0 33
50 6
7 0 2
100 2
PAN 2
WELLS 4-49
EXTRACT FROM WELL LOG
Location: Pancake, TX (approx. 5.6 km west of Waffle)
Boring results (surface elevation at 323 m)
Depth, m Soil description
0–1.8 Soil (Selkirk)
1.8–8.2 Clay, red
8.2–54.0 Galena dolomite
54.0–92.0 Maquoketa shale
92.0–133.9 Someko sand
1 33.9 Well terminated in shale
P umping test results
Static water level before pumping began: 38.7 m below grade
Drawdown in observation well 91.4 from test well pumped at 0.095 m
3
/ s.
T i me from start Drawdown from static
of pumping, min water level, m
20 2.00
100 2.68
1 500 3.79
4-24. Your firm has been retained to develop plans for a well system for the Bastogne
Retirement Center. Using the design elements listed below Problem 4-22 and the fol-
lowing data, design the well system.
a. Population: 150
b. Demand: 400 Lpcd
c. Water is to be supplied from wells. No treatment will be provided.
d. Top of reservoir is
35.8 m above ground level
e. Friction losses minor losses in piping from well to top of reservoir 0.25 m
f. Water supply is to be chlorinated, but no other treatment will be provided.
TEST BORING RESULTS
Bastogne Retirement Center
Bore hole no. 3 (surface elevation: 164 m)
Strata Thickness, m Depth to bottom of strata, m
Soil (Emmet-Trenary) 1 . 5 1 . 5
S a n dy loam 5.1 6.6
Silty clay 6.1 12.7
C l a y 6.1 18.8
U n consolidated sandy clay (water at 6.7 m) 7 5.6 94.4
C l a y 30.5 124.9
S a n d and gravel 45.7 170.6
Shale Boring terminated at 170.6 m
4-50 WATER AND WASTEWATER ENGINEERING
An analysis of the water indicates that it is not corrosive.
Grain size analysis of sand and gravel
U.S. sieve no. Wt. retained, g
6 16.7
8 4 4 . 5
1 0 2 3.0
1 6 56.6
2 0 6 3.1
30 48.5
4 0 34.0
50 53.4
6 0 2 3.3
8 0 4 3.5
100 57.3
PAN 50.2
Total 494.1
EXTRACT FROM WELL LOG
Location: Mt Blanc (approx. 3 km east of Bastogne Retirement Center)
Boring Results (surface elevation at 158.5 m)
Depth, m Soil description
0–0.5 S a n dy loam
0 . 5 –0.9 Sandy clay loam
0.9–1.5 Silty clay
1 . 5–10.7 Clay
10.7–11.1 Sandy loam
11.1–11.7 Sandy clay loam
11.7–12.1 Unconsolidated sandy clay (water at 17.0 m)
12.1–103.6 Clay
1 0 3.6–152.5 Shale
Well terminated in s
hale at 152.5 m
P umping test results
Static water level before pumping began: 2.4 m below grade
Test well pumped at 0.006 m
3
/ s.
Drawdown in observation well 38.1 m from pumping well.
T i me from start Drawdown from static
of pumping, min water level, m
1.0 0.42
2.0 0.53
4.0 0.69
8.0 0.79
10.0 0.85
20.0 0.96
WELLS 4-51
40.0 1.11
60.0 1.17
100.0 1.28
120.0 1.31
180.0 1.39
240.0 1.45
4-7 DISCUSSION QUESTIONS
4-1. An artesian aquifer is under pressure because of the weight of the overlying geologic
strata. Is this sentence true or false? If it is false, rewrite the sentence to make it true.
4-2. For the following well boring log, identify the pertinent hydrogeologic features. The
well screen is set at 6.0–8.0 m, and the static water level after drilling is 1.8 m from
the ground surface.
Strata Depth, m R e marks
Top soil 0.0–0.5
S a n dy till 0.5–6.0 Water encountered at 1.8 m
S a n d 6.0–8.0
C l a y 8.0–9.0
Shale 9.0–10.0 Well terminated
4-3. For the following well boring log (Bracebridge, Ontario, Canada), identify the per-
tinent hydrogeologic features. The well screen is set at 48.0–51.8 m, and the static
water level after drilling is 10.2 m from the ground surface.
Strata Depth, m R e marks
S a n d 0.0–6.1
Gravelly clay 6.10–8.6
Fine sand 8.6–13. 7
C l a y 1 3.7–17.5 C a sing sealed
Fine sand 1 7 . 5–51.8
B e drock 51.8 Well terminated
4-4. Sketch the piezometric profiles for two wells that interfere with one another. Well A
pumps at 0.028 m
3
/ s and well B pumps at 0.052 m
3
/ s. Show the ground water table
before pumping, the drawdown curve of each well pumping alone, and the resultant
when both wells are operated together.
4-8 REFERENCES
AWWA, 1999 Design and Construction of Small Systems, American Water Works Association,
Denver, Colorado.
Boulton, N. S. (1954) “The Drawdown of Water Table under Nonsteady Conditions near Pumped Well in
an Unconfined Formation,” Proceedings of Institute of Civil Engineering (London), vol. 3, part III,
pp. 564–579.
4-52 WATER AND WASTEWATER ENGINEERING
Bouwer, H. (1978) Groundwater Hydrology, McGraw-Hill, New York, pp. 68, 76–79, 175–176.
Campbell, M. D., and J. H. Lehr (1973) Water Well Technology, McGraw-Hill, New York, pp. 45, 137,
139–140.
Cooper, H. H. and C. E Jacob (1946) “A Generalized Graphical Method for Evaluating Formation
Constants and Summarizing Well Field History,” Transactions American Geophysical Union,
vol. 27, pp. 526–534.
Davis, M. L. and D. A. Cornwell (2008) Introduction to Environmental Engineering, McGraw-Hill,
Borton, Massachusetts.
F
erris, J. G., D. B. Knowles, R. H. Brown, and R. W. Stallman (1962) Therory of Aquifer Tests, U.S.
Geological Survey Water-Supply Paper 1536-E, p. 96.
GLUMRB (2003) Recommended Standards for Water Works, Great Lakes–Upper Mississippi River
Board of State and Provincial Public Health and Environmental Managers, Health Education
Services, Albany, New York, p. 21–31.
Hanna, T. M. (2007) “Development of Water Wells,” in R. J. Sterrett (ed.), Ground Water and Wells,
Johnson Screens, A Weatherford Company, New Brighton, Minnesota, pp. 501–550.
Hunter Blair, A. (1970) “Well Screen
s and Gravel Paces,” Ground Water, vol. 8, No. 1, pp. 10–21.
Johnson (1975) Ground Water and Wells, Johnson Division, UOP, Inc., Saint Paul, Minnesota,
pp. 208–276.
MSDWA (1976) Michigan Safe Drinking Water Act, Acts of State of Michigan.
RMC (2007) A Guide to Water Well Casing and Screen Selection, Roscoe Moss Company, Los Angeles,
California, pp. 15–16.
Stollhans, J. R. (2007) personal communication.
Theis, C. V. (1935) “The Relation Between Lowering the Piezometric Surface and the Rate and Discharge
of a Well Using Grou
nd Water Storage,” Transactions American Geophysical Union, vol. 16,
pp. 519–524.
Thiem, G. (1906) Hydrologische Methoden, J. M. Gebhart, Leipzig, Germany.
U.S. EPA (1973) Manual of Individual Water Supply Systems, U.S. Environmental Protection Agency,
Office of Water Supply Programs, Washington, D.C.
U.S. PHS (1965) Recommended State Legislation and Regulations, U.S. Public Health Service,
Department of Health Education and Welfare, Washington, D.C.
Walton, W. C. (1962) “Selected Analytical Methods for Well and Aquifer Evaluation,” Illinois State
Water Survey Bulletin 49.
Walton, W. C. (1970) Groundwater Resource Evaluation, McGraw-Hill, New York, p. 300.