Page 107 - Water Engineering Hydraulics, Distribution and Treatment

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References
In the aquifer represented by the pumping test in Problem
3.7
3
4
−5
3.5 (T = 2.6 × 10 gpd∕ft = 322.87 m ∕d∕mand S = 2.3 × 10 ),
significant amounts. Explain the following briefly:
a gravel-packed well with an effective diameter of 36 in. (914 mm)
(a) The reasons why groundwater is the principal source of water
is to be constructed. The design flow of the well is 1,000 gpm (5450
for small systems,
3
m /d). Calculate the drawdown at the well with total withdrawals
(b) The US EPA’s Groundwater Rule promulgation,
from storage (i.e., with no recharge or leakages) after (a) 1 min, (b)
(c) The meaning of “groundwater under the direct influence of sur-
1 h, (c) 1 day, (d) 1 month, and (e) 1 yr of continuous pumping, at
face water” (GWUDI) and the water monitoring and treatment
design capacity.
requirements of GWUDI.
Determine the drawdown of a quasi-steady state for a pro-
3.8
Define the technical terms of (a) well capacity; (b) uncon-
3.18
posed 36 in. (914 mm) effective diameter well pumping continu-
fined aquifer; (c) confined aquifer; (d) zone of aeration; and (e) zone
3
ously at 350 gpm (1907 m /d) in an elastic artesian aquifer hav-
of saturation.
3
ing a transmissivity of 5000 gpd/ft (62 m /d/m) and a storage
−4
coefficient of 4 × 10 . Assume that the discharge and recharge in soil formations (aquifers) from which it can be withdrawn in
Define the technical terms of (a) groundwater recharge; (b)
3.19
conditions are such that the drawdown will be stabilized after groundwater storage; (c) groundwater safe yield; (d) impounding
180 days. reservoir safe yield; and (e) river safe yield.
3.9 A well was pumped at a constant rate of 500 gpm (2,725
3
m /d) between 8 a.m. and 11 a.m., 2 p.m. and 5 p.m., and remained
idle the rest of the time. What will be the drawdown in the well REFERENCES
at 8 a.m. the next day when a new cycle of pumping is to start?
Assume no recharge or leakage. The transmissivity of the artesian American Society of Civil Engineers, Groundwater basin manage-
(
4
3
)
aquifer is 4.1 × 10 gpd∕ft 509.14 m ∕d∕m . ment, in Manual of Engineering Practice, no. 40, ASCE Pub-
lication, New York, NY, 1961, 160 pp.
3.10 Two wells with effective diameters of 36 in. (914 mm)
are located 1,500 ft (457.2 m) apart in an artesian aquifer with American Water Works Association, Groundwater, AWWA Publi-
−5
4
3
T = 2.5 × 10 gpd∕ft (310.45 m ∕d∕m) and S = 4 × 10 . Compute cation, Denver, CO, 2003, 207 pp.
the drawdown at each well when the two wells are pumped at 500 American Water Works Association, Water Resources Planning,
3
gpm (2725 m /d) for 20 days. AWWA Publication, Denver, CO, 2007, 378 pp.
3.11 Suppose it is desired to restrict the drawdown in each of American Water Works Association, Water Resources, AWWA Pub-
the wells to 40 ft in Problem 3.10. What will be the corresponding lication, Denver, CO, 2010, 210 pp.
discharges for individual wells?
Batu, V., Aquifer Hydraulics: A Comprehensive Guide to Hydro-
3.12 A gravel-packed well with an effective diameter of 36 in. geologic Data Analysis, John Wiley & Sons, Inc., New York,
(914 mm) pumps water from an artesian aquifer having T = 4.2 × 1998.
3
−5
4
10 gpd∕ft (521.56 m ∕d∕m) and S = 4.4 × 10 . The well lies at a
Brown, R. H., Selected procedures for analyzing aquifer test
distance of 2,000 ft (610 m) from a stream that can supply water
data, Journal of American Water Works Association, vol. 45,
fast enough to maintain a constant head. Find the drawdown in the pp. 844–866, 1953.
3
well after 20 days of pumping at 550 gpm (2725 m /d).
Brown, R. H., Drawdowns resulting from cyclic intervals of dis-
3.13 The interrelationship of pumping rate, drawdown, and spe-
charge, in Methods of Determining Permeability, Transmissi-
cific yield serves as a basis for the selection of optimal design bility and Drawdown, U.S. Geological Survey Water Supply
capacity. List the factors on which the obtainable yield from a well Paper 1537–1, 1963.
depends.
Department of Water Supply website, County of Maui, Hawaii,
3.14 A well having an effective diameter of 36 in. (914 mm) http://co.maui.hi.us/index.aspx?NID=126, 2014.
is to be located in a relatively homogeneous artesian aquifer with
3
a transmissivity of 15,000 gpd/ft (186.27 m /d/m) and a storage Downing, A. and Wilkinson, W. B., Applied Groundwater Hydrol-
−4
coefficient of 3 × 10 . The initial piezometric surface level is 30 ft ogy: A British Perspective, Oxford University Press, Oxford,
UK, 1992.
(9.14 m) below the land surface. The depth to the top of the aquifer
is 140 ft (42.67 m) and the thickness of the aquifer is 60 ft (18.28 m). Edward, E., Groundwater and Wells, Johnson, Inc., Saint Paul, MN,
The well is to be finished with a screen length of 30 ft (9.14 m). 1966.
Compute the specific capacity of the well and its maximum yield Fair, G. M., Geyer, J. C., and Okun, D. A., Water and Wastewater
after 10 days of pumping. Neglect well losses. Engineering, Vol. 1: Water Supply and Wastewater Removal,
3.15 Discuss the sanitary protection of wells constructed for sup- John Wiley & Sons, Inc., New York, 1966.
plying drinking water. Fair, G. M., Geyer, J. C., and Okun, D. A., Elements of Water Supply
3.16 Visit the US Environmental Protection Agency website and Wastewater Disposal, John Wiley & Sons, Inc., New York,
(www.epa.org) and find the Groundwater Rule (GWR). Explain 1971.
the background of the GWR and outline briefly the most recent Hantush, M. S., Hydraulics of wells, Advances in Hydroscience,
final GWR final requirements. vol. 1, p. 281, 1964.
3.17 About 25% of Earth’s freshwater supply is stored beneath Hantush, M. S. and Jacob, C. E., Nonsteady radial flow in an infi-
the surface of the land, where it remains for thousands of years. nite leaky aquifer, Transactions of the American Geophysical
Only a relatively small proportion of this groundwater is located Union, vol. 36, no. 1, pp. 95–100, 1955.