2006-12-19_REVISION - M2001107

• Permit No: M2001107
• IBM Index Class Name: Revision
• Doc Date: 12/19/2006
• Doc Name: Adequacy Review Response
• From: J&T Consulting, Inc.
• To: DRMS
• Type & Sequence: TR3
• Media Type: D
• Archive: No

WELL HYDRAULICS
Grou ntl surtace
tllus of well ~ ~ Dept h to
R water
~ table
~' Radius of influence
_ -SWL-
Cone of
depression /
Draw oown
Drawdown curve in well,
H- h
Pumping water level- H
Saturated °_
thickness o! h
lormatian
_
before
-
Pumping _
Well screen

I

213
Ground surface
R
Ratlius of inauence
~~ Cona of
\depression
Drawdown curve
Ipotentiometric surtace,
Depth fb stack
potentiometric surtace
__ /i
/ ~Drawtlown
in well,
H-h
Pumping water level-
Thickness of
water-bearing
formation
Figure 9.8. Well in an unconfined aquifer showing Figure 9.9. Well in a tronfined aquifer showing the
the meaning of the various terms used in the equi- meaning of various terms used in the equilibrium
librium equation. equation.
tions, all dynamic conditions in the well and ground are assumed to be in 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
International System of Untts*
Q = 1.366 K (H' - h=)
log R/r
where
(9./)
Q =well yield or pumping rate, in gpm Q =well yield or pumping rate, in m'/day
K =hydraulic conductivity of the water- 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
bearing formation, in m'/dayJmr
(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 [o the [nternaiional System of Units from the older English sys-
tem. For years the scientific community has used the metric system [now System International (Sq], 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 ofmeasure are given throughout this text; the SI notation is on the right ofeach page and
the English system is on the lets. 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 in Appendiz 9.8.
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