2013-07-03_REVISION - M1985112 ‎(3)‎

• Permit No: M1985112
• IBM Index Class Name: REVISION
• Doc Date: 7/3/2013
• Doc Name: TR Submittal
• From: Loloff Construction, Inc.
• To: DRMS
• Type & Sequence: TR1
• Media Type: D
• Archive: No

WELL HYDRAULICS
Ground surface
Radius of well- r A
pe to
R water table
4 Radius of influence — _ SWL-
cone of /
depression
Drawdown
Drawdown curve in well.
H - h
Pumping water level- H
Saturated �_
thickness of - h
formation
before
pumping
Well screen
Figure 9.8. Well in an unconfined aquifer showing
the meaning of the various terms used in the equi-
librium equation.
R
14- Radius of influence
-� Cone of
-,,depression
Drawdown curve
(potenhometnc surface)
Pumping water level—
Thickness of
water - bearing
formation
213
Ground surface
Depth to static
potent4ometnc surface
i
/ ZDawdown
rn well,
H - h
H
Figure 9.9. Well in a confined aquifer showing the
meaning of various terms used in the equilibrium
equation.
tions, all dynamic conditions in the well and ground are assumed to be to equilibrium,
that is, the discharge is constant, the drawdown and radius of influence have stabilized,
and water enters the well in equal volumes from all directions. Both assume horizontal
flow everywhere in the aquifer with recharge occurring at the periphery of the cone of
depression. Figure 9.8 shows a vertical section of a well constructed in an unconfined
aquifer. The equation for the well yield of an unconfined aquifer is:
English Engineering Units*
K (H2 - h')
Q 1,055 log R/r
where
Q = well yield or pumping rate, in gpm
K = hydraulic conductivity of the water -
bearing formation, in gpd /ft-
H = static head measured from bottom
of aquifer, in ft
h =depth of water in the well while
pumping, in ft
International System of Units*
1.366 K (H2 - h2)
Q log R/r
where
Q = well yield or pumping rate, in m`/ day
K = hydraulic conductivity of the water -
bearing formation, in m` /day /m2
(m /day)
H= static head measured from bottom
of aquifer, in m
h =depth of water in the well while
pumping, in m
'The United States is slowly converting to the International System of Units from the older English sys-
tem. For years the scientific community has used the metric system (now System International (SI)1, but
only recently have other business and technological entities adopted it. In the future, many engineers and
drillers will have to present information in the metric system. Therefore, equations in both the Sl and
English systems of measure are given throughout this text; the SI notation is on the night of each page and
the English system is on the left. The complete International System of Units as it applies to water re-
sources is given in Appendix 9.A. A convenient unit conversion table is also provided. Symbols used in
the text are given to Appendix 9.B.
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