Pumping tests, epa guidance

TECHNICAL GUIDANCE MANUAL FOR HYDROGEOLOGIC
INVESTIGATIONS AND GROUND WATER MONITORING
CHAPTER 4
SLUG AND PUMPING TESTS
February 1995

-ii-
TABLE OF CONTENTS
SINGLE WELL TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
SLUG TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
Design of Well . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Number of Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Test Performance and Data Collection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Modified Slug Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2
Packer Tests Within A Stable Borehole . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Pressure Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-3
Vacuum Tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-4
Analysis of Slug Test Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
SINGLE WELL PUMPING TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6
MULTIPLE WELL PUMPING TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
PRELIMINARY STUDIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9
PUMPING TEST DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Pumping Well Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Pumping Well Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-12
Pumping Rate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Pump Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-13
Observation Well Number . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
Observation Well Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
Observation Well Depth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
Observation Well Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-14
Duration of Pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16
Discharge Rate Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Discharge Measuring Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Interval of Water Level Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Pretest Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17
Measurements During Pumping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-18
Measurements During Recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19
Water Level Measurement Devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-19
Discharge of Pumped Water . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20
Decontamination of Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20
CORRECTION TO DRAWDOWN DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-20
Barometric Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22
Saturated Thickness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-22
Unique Fluctuations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23
Partially-Penetrating Wells . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23
ANALYSIS OF MULTIPLE WELL PUMPING TEST DATA . . . . . . . . . . . . . . . . . . . . . . . . 4-23
RECOVERY TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-24
PRESENTATION OF DATA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-36
SINGLE WELL TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-36
MULTIPLE WELL PUMPING TESTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-36
REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-39

CHAPTER 4
SLUG AND PUMPING TESTS
Slug and pumping tests are used to determine in-situ properties of water-bearing formations and
define the overall hydrogeologic regime. Such tests can determine transmissivity (T), hydraulic
conductivity (K), storativity (S), connection between saturated zones, identification of boundary
conditions, and the cone of influence of a pumping well in a ground water extraction system. To
enable proper test design, it is important to define objectives and understand site hydrogeology as
much as possible. Methods, instruments, and operating procedures should be specified in a
workplan. The results of tests, methods, and any departures from the work plan that were
necessary during implementation should be documented in a report.
This chapter covers various types of tests, including single well and multiple well. Their advantages
and disadvantages and the minimum criteria that should be considered prior to, during, and after
implementation are summarized. It is beyond the scope of this document to address all details on
test design and analysis; therefore, additional sources have been referenced.
SINGLE WELL TESTS
A single well test involves pumping, displacing, or adding water and measuring changes in water
levels in the well. This type of test allows a rapid and economical calculation of K and T of the zone
of interest at a single location. Single well tests also can determine response criteria for
observation wells in multiple well pumping tests.
Single well tests should be conducted in properly designed and developed wells or piezometers.
If development is inadequate, the presence of drilling mud filter cake (use of mud is not
recommended) or the smearing of fine-grained material along the borehole wall may result in data
that indicate an artificially low K. This may lead to underestimation of contaminant migration
potential. Drilling methods, well design and installation, and well development are covered in
Chapters 6, 7 and 8, respectively. The various types of tests are discussed briefly below.
AdditionalinformationcanbefoundindocumentsbyBlack(1978),Chirlin(1990),DawsonandIstok
(1991), Kruseman and de Ridder (1991), and Lohman (1972).
SLUG TESTS
A slug test involves the abrupt removal, addition, or displacement of a known volume of water and
the subsequent monitoring of changes in water level as equilibrium conditions return. The
measurements are recorded and analyzed by one or more methods. The rate of water level change
is a function of the K of the formation and the geometry of the well or screened interval.
Slug tests generally are conducted in formations that exhibit low K. They may not be appropriate
in fractured rock or formations with T greater than 250 m2
/day (2, 690 ft 2
/day) (Kruseman and de
Ridder, 1991); however, in some instances, a vacuum or slug test conducted with a pressure
transducer or electronic data logger may be warranted.

4-2
Hydraulic properties determined by slug tests are representative only of the material in the
immediate vicinity of the well; therefore, slug tests should not be considered a substitute for
conventionalmultiple well tests. Due to the localized nature of hydraulic response, the test may be
affected by the properties of the well filter pack. Therefore, the results should be compared to
known values for similar geologic media to determine if they are reasonable.
If slug tests are used, the designer should consider the amount of displaced water, design of the
well, number of tests, method and frequency of water level measurements, and the method used
to analyze the data.
Design of Well
Well depth, length of screen, screen slot size and length, and distribution of the filter pack must be
known and based on site-specific boring information in order for a well to be used as a valid
observation point. For example, equations used in data analysis make use of the radii of the well
and borehole. The nature of the materials comprising the screened interval (i.e., thickness, grain
size, and porosity of the filter pack) also must be known.
Number of Tests
Properties determinedfromslugtestsatasinglelocationarenotveryusefulforsitecharacterization
unless they are compared with data from tests in other wells installed in the same zone. When
conducted in large number, slug tests are valuable for determining subsurface heterogeneity and
isotropy. The appropriate number depends on site hydrogeologic complexity.
Test Performance and Data Collection
Data collection should include establishment of water level trends prior to and following the
application of the slug. Pre-test measurements should be made until any changes have stabilized
and should be taken for a period of time, at least as long as the expected recoveryperiod. Water
levelmeasurements in low-permeability zones may be taken with manual devices. Automatic data
loggers should be used for tests of high permeability zones. Slug tests should be continued until
at least 85-90 percent of the initial pre-test measurement is obtained (U.S. EPA, 1986).
Whenever possible, water should either be removed by bailing or it should be displaced by
submerging a solid body. According to Black (1978), an addition of water invariably arrives as an
initial direct pulse followed by a subsequent charge that runs down the sides of a well. This may
result in a response that is not instantaneous, which may subsequently influence the data (Figure
4.1). An advantage of displacement is that it allows for collection and analysis of both slug injection
and slug withdrawal data. However, slug injection tests should not be conducted in wells where the
screened interval intercepts the water table.
The volume of water removed or displaced should be large enough to insure that build-up or
drawdown can be measured adequately, but it should not result in significant changes in
saturated zone thickness (Dawson and Istok, 1991). It should be large enough to change water level
by 10 to 50 centimeters (Kruseman and de Ridder, 1991). Field procedures for slug tests are also
described in ASTM D 4044-91 (1992).

1
Skin effects result from locally increasing the K near the well by opening fractures (positive skin) or decreasing the K (negative skin) by
filling voids or coating borehole walls with drilling cuttings (Sevee, 1991).
4-3
Figure 4.1 Results of a slug test with addition of water. Water arrives as an initial direct
pulse followed by a subsequent charge that runs down the sides of the well
(Source: Adapted from Black, 1978).
Modified Slug Tests
Inaddition to removal or displacement of water, a change in static water level can be accomplished
by pressurizing a well with air or water or by creating a vacuum. Packers are often used to seal the
zone to be tested.
Packer Tests Within A Stable Borehole
Horizontal K for consolidated rock can be determined by a packer test conducted in a stable
borehole (Sevee, 1991). A single packer system can be used when testing between a packer and
the bottom of the borehole (Figure 4.2A). Two packer systems can be utilized in a completed
borehole at any position or interval (Figure 4.2B). A packer is inflated using water or gas. Water
should be injected for a given length of time to test the packed-off zone.
Pressure Tests
A pulse or a pressure test may be appropriate in formations where K can be assumed to be lower
than 10-7
cm/sec. In a pulse test, an increment of pressure is applied into a packed zone. The
decay of pressure is monitored over a period of time using pressure transducers with electronic
data loggers or strip-chart recorders. The rate of decay is related to the K and S of the formation
being tested. This test generally is applied in rock formations characterized by low K.
Compensation must be made for skin effects1
and packer adjustments during the test. An
understanding of the presence and orientation of fractures is necessary to select an appropriate
type curve to analyze test data (Sevee, 1991).

4-4
Vacuum Tests
According to Orient et al. (1987), vacuum tests can be used to evaluate the K of glacial deposits
and compare favorably to more conventional methods. Figure 4.3 shows typical test design. In
general, water level is raised by inducing vacuum conditions. Once it reaches the desired height
and sufficient time has been allowed for the formation to return to its previous hydrostatic
equilibrium, the vacuum is broken and the recovery is monitored. The data is evaluated using the
same techniques that are used to evaluate conventional slug test data.
Figure 4.2 In-Situ packer testing. A - Single packer system, test conducted during drilling. B - Double
packer system, test conducted after borehole is complete (Source: Design and Installation of Ground Water
Monitoring Wells by D.M. Nielsen and R. Schalla,Practical Handbook of Ground Water Monitoring, edited by David M. Nielsen,
Copyright©1991bypermission.)Lewis Publishers, an imprint of CRC Press, Boca Raton, Florida.
With permission.)
Copyright requirements preclude including the
figure on Ohio EPA’s Web page. Please see
original source.

4-5
Figure 4.3 Vacuum testing setup (Source: Vacuum and Pressure Test Methods for Estimating
Hydraulic Conductivity by J.P. Orient, A. Nazar and R.C. Rice. Ground Water Monitoring
Review. Volume 7, No. 1, Page 50 (Figure 5). 1987. Reprinted from Ground Water
Monitoring Review with permission from the National Ground Water Association.
Copyright 1987.)

4-6
T '
43.08Q
Sw
Analysis of Slug Test Data
Mathematical models for slug test data analysis are summarized in Table 4.1. Models have been
developed to deal with confined, unconfined, partial penetration, and skin effects. Calculation of K
for a fully screened zone is achieved by dividing T by the entire thickness of the zone. A test of a
partially penetrating well yields a T value that is only indicative of that portion of the zone that is
penetrated by the well screen. Results from slug tests should not be "over-interpreted". The values
obtained are for the geologic material immediately surrounding the well intake, which invariably has
been altered to some degree by the installation process.
SINGLE WELL PUMPING TESTS
A single well pumping test involves pumping at a constant or variable rate and measuring changes
inwater levels during pumping and recovery. Such tests are used to determine T and K when water
level recovery is too rapid for slug tests and no observation wells or piezometers are available.
A simplistic single well test consists of pumping at a constant rate and measuring drawdown. When
the water level has stabilized, steady flow conditions can be assumed and the following variation
ofthe Theim equation can be used for estimating T (modified from Boonstra and de Ridder, 1981):
where: Q = the constant well discharge in feet3
/day.
Sw = the stabilized drawdown inside the well at steady flow in feet.
T = the transmissivity.
The equation can be applied to data for both confined and unconfined zones; however, for
unconfined zones, drawdown (sw) must be corrected to sw' = sw - (s2
w/2D), where D is the saturated
zone thickness in feet. Appreciable error can be made in calculating for T using this equation,
especially if well construction is unknown or inaccurate or if the screen is partially clogged (Boonstra
and de Ridder, 1981). The equation, T = KD can be utilized to determine K.
The drawdown in a pumped well is influenced by well loss and well-bore storage. Well loss is
responsible for drawdown being greater than expected from theoretical calculations and can be
classified as linear or non-linear. Linear loss is caused by compaction and/or plugging of
subsurface material during well construction and installation and head loss in the filter pack and
screen. Non-linear loss includes head loss from friction within the screen and suction pipe. Since
well-bore storage is large when compared to an equal volume of formation material, it must be
considered when analyzing drawdown data from single well pumping tests (Kruseman and de
Ridder, 1991). However, Papadopulos and Cooper (1967) observed that the influence of well-bore
storage on drawdown decreases with time (t) and becomes negligible at t > 25rc
2
, where rc is the
radius of the unscreened part ofthe well where the water level is changing. The effects of well-bore
storage on early-time drawdown data can be determined by a log-log plot of drawdown (sw) verses
time (t). Borehole storage effects exist if the early-time drawdown data plots as a unit-slope straight
line (Kruseman and de Ridder, 1991).

Table 4.1 Analysis methods for slug tests.
GENERAL ASSUMPTIONS
1. The aquifer has an apparently infinite areal extent.
2. The zone is homogeneous and of uniform thickness over the area influenced by the test (except when noted in application column).
3. Prior to the test, the water table or piezometric surface is (nearly) horizontal over the area influenced and extends infinitely in the radial direction.
4. The head in the well is changed instantaneously at time to = 0.
5. The inertia of the water column in the well and the linear and non-linear well losses are negligible (i.e., well installation and development process are assumed
to have not changed the hydraulic characteristics of the formation).
6. The well diameter is finite; hence storage in the well cannot be neglected.
7. Ground water density and viscosity are constant.
8 No phases other than water (such as gasoline) are assumed to be present in the well or saturated portion of the aquifer.
9. Ground water flow can be described by Darcy's Law.
10. Water is assumed to flow horizontally.
APPLICATION
METHOD "Aquifer"
Type
Flow
Condition
Can account for ADDITIONAL
ASSUMPTIONS
PROCEDURE/ANALYSIS REMARKS
Partial
Penetration
Anisotropic
Cooper et al.
(1967) (a,b)
Confined Transient No No - The rate at which the
water flows from the well
into the aquifer (or vice
versa) is equal to the rate
at which the volume of
water stored in the well
changes as the head in
the well falls or rises
- Conventional**
- Type curve analysis
Difficult to match due to
similarities of type curve.
- Also described in
ASTM D4104-91 (1992)
Bouwer and
Rice (1976)
Bouwer (1989)
(a,b)
Unconfined
or leaky*
Steady
state
Yes No - Aquifer is
incompressible
- Buildup of the water
table is small compared
to aquifer thickness
- Conventional**
- Calculations based on
modified Theim equation
and geometric parameters
- Can be used to
estimate the K of leaky
aquifers that receive
water from the upper-
semi confining layer
through recharge or
compression

Table 4.1 (continued): Analysis Methods of Slug tests.
APPLICATION
METHOD "Aquifer"
Type
Flow
Condition
Can account for ADDITIONAL
ASSUMPTIONS
PROCEDURE/ANALYSIS REMARKS
Partial
Penetration
Anisotropic
Hvorslev
(1951) (a)
Confined or
Unconfined*
Transient Yes Yes - The injection well is
considered to be a slot
(line source) with
infinitesimal width
- Conventional
- Analytical equations and
calculations of hydraulic
equation based on test
conditions
- Differences of 0.3X to
0.5X can be observed
when comparing the K
calculated from other
methods
- In some cases can be
applied to unconfined
aquifers, Fetter (1988)
Bredehoeft
and
Papadopulos
(1980)
Confined Transient Yes - Modified
- Measure decay of head
change by pressurizing a
volume of water in the well
- Type curves
- Type curves
- Low to extremely low K
(i.e. silts, clays, shales)
Uffink (1984)
(Oscillation
Test) (b)
Confined Transient No -Inertia of water column is
not negligible, the head
change in the well at t> to
can be described as an
exponentially damped
cyclic fluctuation
- Storativity (s) and the
skin factor are already
known or can be
estimated
- Modified
- Stress zone by lowering
water table by compressed
air. Calculate K by
Hvorslev method.
* see remarks
** conventional refers to either injecting or withdrawing or displacing using a solid slug
a Described in Dawson and Istok (1991)
b Described in Kruseman and de Ridder (1991)

4-9
A step-drawdown test can be conducted to account for well loss. This test involves pumping at a
constant rate until drawdown has stabilized. The rate of pumping is then increased. This process
should be repeated through a minimum of three steps. Methods for analyzing the data have been
summarized by Kruseman and de Ridder (1991).
Table 4.2 presents several methods for analyzing the drawdown data for constant discharge,
variable discharge, and step-discharge single well tests. Analysis of recovery test data (residual
drawdown) is invaluable with a single well pumping test. Methods for analysis are straight line
methods, which are the same as for conventional pumping tests. However, with single well tests,
one must account for the effects of well-bore storage when evaluating recovery (Kruseman and de
Ridder, 1991). Available methods to analyze recovery are discussed in the Multiple Well Pumping
Tests section of this chapter.
MULTIPLE WELL PUMPING TESTS
A multiple well test is implemented by pumping a well continuously and measuring water level
changes in both the pumped and observation wells during pumping or subsequent recovery.
Properlydesignedandconductedmultiplewelltestscanbeusedtodefinetheoverallhydrogeologic
regime of the area being investigated, including T, S and/or specific yield of a zone. They also can
help design municipal well fields, predict rates of ground water flow, determine interconnectivity
between saturated zones, and design a remediation system.
Two basic types are constant discharge and variable discharge. The former is performed by
pumping at a constant rate for the duration of the test, while the latter is distinguished by changes
in rate. Measurements obtained from the pumping well generally are less desirable for calculating
hydraulic properties because of the irregularities induced from the operation of the pump and well
bore storage. Obtaining data from observation well(s) allows for characterization of the pumped
zone over a larger area.
Test design and data analysis are dependent on the characteristics of the zone tested, the
desired/required information, and available funds. Design and analysis are summarized below.
References suggested for more detailed information include Lohman (1972), Walton (1987),
Dawson and Istok (1991), and Kruseman and de Ridder (1991).
PRELIMINARY STUDIES
Prior to initiating a test, the following data should be gathered:
• The geologic characteristics of the subsurface that may influence ground water flow.
• The type of water-bearing zone and its lateral and vertical extent.
• The depth, thickness, and lateral extent of any confining beds.
• Location of recharge and discharge boundaries.
• Horizontal and vertical flow components (e.g., direction, gradient)
• Location, construction, and zone of completion of any existing wells in the area.
• Location and effects of any pumping wells.
• Approximate values and spatial variation of formation T and S.
• Determination of seasonal ground water fluctuations and any regional water level trends.

Table 4.2 Single well pumping tests.
GENERAL ASSUMPTIONS
1. The aquifer is infinite in areal extent.
2. The aquifer is homogeneous, isotropic, and of uniform thickness over the area influenced by the test.
3. Prior to pumping, the piezometric surface is horizontal, or nearly so, over the area to be influenced by the test.
4. The well penetrates the entire thickness of the aquifer and, thus, receives water by horizontal flow.
5. The water removed from storage in the aquifer is discharged instantaneously with decline of head.
6. Non-linear well losses are negligible.
The following assumptions/conditions apply to leaky confined aquifers.
1. The aquitard is infinite in areal extent.
2. The aquitard is homogeneous, isotropic and of uniform thickness.
3. The water supplied by leakage from the aquitard is discharged instantaneously with decline in head.
APPLICATION
METHOD "Aquifer" Type Flow
Condition
ADDITIONAL
ASSUMPTIONS/CONDITIONS
ANALYSIS/PROCEDURE REMARKS
Papadopulos and
Cooper (1967)
(a & b)
Confined Transient The well diameter cannot be considered
infinitesimal, hence, storage in well cannot
be neglected
Constant discharge
Equations take storage
capacity of well into
account
Type curves, data curve,
log/log
- Early time data does
not adequately reflect
aquifer characteristics
- May be difficult to
match the data curve
with appropriate type
curves because of
similarities of curves
Rushton and Singh
(1983) (b)
Confined Transient The well diameter cannot be considered
infinitesimal, hence storage in well cannot
be neglected
Constant discharge
Type curve fitting, data
curve semi-log
More sensitive curve
fitting than Papadopulos
and Cooper method
Birsoy and
Summers(1980) (b)
Confined Transient Storativity is known or can be estimated
with reasonable accuracy
Variable discharge (aquifer
is pumped stepwise or is
intermittently pumped at
constant discharge)
Hurr-Worthington
(Worthington, 1981)
(b)
Confined or leaky
confined
Transient Storage in well cannot be neglected.
Storativity is known or can be estimated
with reasonable accuracy
Constant discharge
Modified Theis Equation

Table 4.2 (Continued): Single well pumping tests.
APPLICATION
METHOD "Aquifer" Type Flow
Condition
ADDITIONAL
ASSUMPTIONS/CONDITIONS
ANALYSIS/PROCEDURE REMARKS
t < 25
r
2
c
KD
t <
cS
20
Jacob's Straight Line
Method (b)
Confined or leaky
confined
Transient For confined,
if net effect of
well borestorage can be neglected.
For leaky, 25
r
2
c
KD
< t <
cS
20
as long as the influence of
leakage is negligible.
Constant discharge
T determined by drawdown
differences
Sensitive to minor
variations in discharge
rate
May be able to account
for partial penetration if
late-time data is used
Hantush (1959b) (b) Leaky
confined/artesian
Transient Flow through aquitard is vertical
Aquitard is incompressible (i.e. changes in
aquitard storage are negligible)
At the beginning of the test (t=0), the water
level in the well is lowered instantly, at t>0,
the drawdown in the well is constant and
its discharge is variable
Variable discharge
Type curve matching
Jacob and Lohman
(1952)(b)
Confined/artesian Transient At the beginning of the test (t=0), water
levels screened in the artesian aquifer are
lowered instantaneously.
At t>0, the drawdown is constant and
discharge is variable
Uw <0.01
Variable discharge
(drawdown is constant)
If value of the effective
radius is not known then
storativity cannot be
determined
a Described in Dawson and Istok (1991), b Described in Kruseman and deRidder (1991)
t = time since start of pumping, KD =transmissivity of the aquifer, rc = radius of the unscreend part of the well where water level is changing, c = hydraulic resistance of the
aquitard, S = storativity, Uw = equation function

4-12
This preliminary information can assist in the proper design of the test and the choice of a
conceptual model. Test design also can be facilitated by preminary conceptual modeling efforts
that predict the outcome of the test beforehand (Walton, 1987). This serves two purposes. First,
it describes the aquifer so that an appropriate data analysis method is evident. Secondly, it
suggests deficiencies in observation well locations.
Costs frequently are reduced by using existing wells rather than installing new ones; however, few
existing configurations are suitable. Evaluation of existing wells to identify ones that are potentially
useable is the first step in design (Stallman, 1983). Single well tests should be conducted on the
existing wells to determine whether they will respond appropriately.
PUMPING TEST DESIGN
As indicated, the design of a pumping test is dependent on the hydrogeologic environment and the
purpose of the test. The designer must determine pumping well location and design, pumping rate,
pump selection, location and depth of observation wells, test duration, discharge rate
measurements and devices, interval and method of water level measurements, and method of
analyzing data.
Pumping Well Location
A pumping well should be located far enough away from hydraulic boundaries to permit recognition
of drawdown trends before boundary conditions influence the drawdown data (Sevee, 1991). To
minimize the effect of stream, river or lake bed infiltration, it should be located at a distance equal
to or exceeding the aquifer thickness from the possible boundary (Walton, 1987). However, if the
intent is to induce recharge, then the pumping well should be located as close to the boundary as
possible (Sevee, 1991). The appropriate depth should be determined from exploratory boreholes
or logs from nearby wells.
Pumping Well Design
The design of a pumping well is dependent on the hydrogeologic environment, the choice of
conceptualmodel, and economics. Components that must be considered include diameter, length
and depth of the screened interval, and screen slot configuration.
A general rule is to screen the well over at least 80 percent of the aquifer thickness. This makes it
possible to obtain about 90 percent or more of the maximum yield that could be obtained if the
entire aquifer were screened, and also allows horizontal flow toward the well to be assumed, which
is an assumption that underlies almost all well-flow equations. Pumping wells completed in thick
zones often have intake lengths less than 80 percent of the thickness. These wells are considered
partially-penetrating (Kruseman and deRidder, 1991), and pumping would be expected to induce
vertical flow components. As a result, corrections to the drawdown data may be necessary.
Corrections are discussed later in this chapter.
The diameter of a pumping well is dependent on the conceptual model and the estimated hydraulic
properties. It must accommodate the pump, assure hydraulic efficiency, and allow measurement
of depth to water before, during and after pumping. Table 4.3 recommends casing diameters

4-13
based onpumpingrates;however,thefinalselectionshouldbebasedonconsultationwiththepump
manufacturer.
The screen slot size and filter pack material should be based on the grain size distribution of the
zone being pumped. The screen should be factory-slotted or perforated over no more than 30 to
40 percent of its circumference to keep entrance velocity less than 3 cm/sec (Kruseman and de
Ridder, 1991). At this velocity, friction losses in the screen are small and may be considered
negligible. Slots should be long and narrow or continuous. The screen should be factory-produced.
Slots produced manually are not appropriate under any circumstances.
Table 4.3 Recommended pumping well diameter for various pumping rates.
(Dawson and Istok, 1991, after Driscoll, 1986).
PUMPING RATE DIAMETER
gal
min
m3
day (in) (mm)
<100
75-175
150-350
300-700
500-1000
800-1800
1200-3000
<545
409-954
818-1910
1640-3820
2730-5450
4360-9810
6540-16400
6
8
10
12
14
16
20
152
203
254
305
365
406
508
Pumping Rate
Insufficientpumpingratesmayresultinunderestimationofthehydraulicparametersofboththezone
tested and confining layers. Likewise, excessive rates for too short a duration may lead to
calculationof erroneously large hydraulic properties. The rate(s) should be sufficient to ensure that
the aquifer is stressed and that drawdown can be measured accurately. The water table in an
unconfined zone should not be lowered by more than 25 percent. This is the largest drawdown that
canbecorrectedandanalyzedwithananalyticalsolutionofthegroundwaterflowequation(Dawson
and Istok, 1991). The pumping rate for tests conducted in confined zones should not readily
dewater the pumping well.
Well efficiency and an appropriate pumping rate for a constant discharge test can be determined
by conducting a step-drawdown test. A step test involves pumping a single well at a low constant
rate until the drawdown within the well has stabilized. The rate is then increased to a higher constant
discharge until the water level has stabilized once more. At a minimum, to insure that an
appropriate rate can be determined from the data, three successively greater rates of equal
durationshould be utilized. The duration of each step generally should be at least 2 hours; however,
the required time is dependent on aquifer characteristics. References detailing the mechanics of
a step test include Kruseman and de Ridder (1991), Driscoll (1986), and Dawson and Istok (1991).

4-14
Other methods that may be useful to estimate an appropriate pumping rate for a constant head test
include: 1) using an empirical formula to predict well specific capacity, and 2) predicting drawdown
using analytical solutions. These methods are described by Dawson and Istok (1991). It should be
noted that these techniques predict discharge rates that can be utilized to determine hydraulic
parameters and should not be utilized to estimate an appropriate rate for capturing a contaminant
plume.
Pump Selection
The pump and power supply must be capable of operating continuously at an appropriate constant
discharge rate for at least the expected duration of the test. Pumps powered by electric motors
produce the most constant discharge (Stallman, 1983).
Observation Well Number
The appropriate number of observation wells depends on the goals of the test, hydrogeologic
complexity, the degree of accuracy needed, and economics. Though it is always best to have as
manywells as conditions permit, at least three should be employed in the pumping zone (Kruseman
and de Ridder, 1991). If two or more are available, data can be analyzed by both drawdown versus
time and drawdown versus distance relationships. Using both and observing how wells respond
in various locations provides greater assurance that: 1) the calculated hydraulic properties are
representative of the zone being pumped over a large area, and 2) any heterogeneities that may
affect the flow of ground water and contaminants have been identified. In areas in where several
complexboundaries exist, additional wells may be needed to allow proper interpretation of the test
data (Sevee, 1991).
Observation Well Design
Ingeneral, observation wells need to be constructed with an appropriate filter pack, screen slot size,
and annular seal, and must be developed properly. Practices for design and development of
observation wells can be similar to those for monitoring wells (see Chapters 7 & 8). The
observation wells/piezometers must be of sufficient diameter to accommodate the measuring
device, but should not be so large that the drawdown cannot be measured.
Observation Well Depth
Fully-penetrating wells are desirable. The open portion of an observation well generally should be
placed vertically opposite the intake of the pumping well. When testing heterogeneous zones, it is
recommended that an observation well be installed in each permeable layer. Additional wells
should be placed in the aquitards to determine leakage and interconnectivity (Kruseman and de
Ridder, 1991).
Observation Well Location
Observation well location is dependent on the type of aquifer, estimated transmissivity, duration of
the test, discharge rate, length of the pumping well screen, whether the aquifer is stratified or

4-15
M.D.$$ 1.5 D
KH
KV
fractured,and anticipated boundary conditions. Placing observation wells 10 to 100 meters (33 to
328 feet) from the pumping well is generally adequate for determining hydraulic parameters. For
thick or stratified, confined zones, the distance should be greater (Kruseman and de Ridder, 1991).
It also is recommended that additional observation wells be located outside the zone of influence
of the pumping well to monitor possible natural changes in head.
Ingeneral, observation wells completed in a confined zone can be spaced further from the pumping
well than those completed in an unconfined aquifer. The decline in the piezometric surface of
confined zones spreads rapidly because the release of water from storage is entirely due to
compressibility of water and the aquifer material. Water movement in unconfined zones is
principally from draining of pores, which results in a slower expansion.
Under isotropic conditions, the distribution of the observation wells around the pumping well can be
arbitrary. However, an even distribution is desirable so that drawdown measurements are
representative of the largest volume of aquifer possible (Dawson and Istok, 1991). If feasible, at
least three wells should be logarithmically spaced to provide at least one logarithmic cycle of
distance-drawdown data (Walton, 1987). If anisotropic conditions exist or are suspected, then a
single row of observation wells is not sufficient to estimate the directional dependence of
transmissivity. A minimum of 3 observation wells, none of which are on the same radial arc, is
required to separate the anisotropic behavior.
The length of the pumping well screen can have a strong influence on the distance of the observation
wells from the pumping well. Partially-penetrating pumping wells will induce vertical flow, which is
most noticeable near the well (Figure 4.4). As a result, water level measurements taken from these
wells need to be corrected; however, the effects of vertical flow become more negligible at
increasing distances from the pumping well. For partially-penetrating pumping wells, corrections
to the drawdown data may not be necessary if the following relation holds true (Sevee, 1991; and
Dawson and Istok, 1991):
M.D. = minimum distance between pumping well and observation well.
D = thickness of the aquifer.
KH = horizontal K.
KV = vertical K.
Drawdown measured in observation wells located less than the minimim distance should be
corrected. Typically, horizontal K is ten times greater than vertical K. If this ratio is used, then the
minimum distance becomes 1.5D/10. It should be noted that partially-penetrating wells located
at or greater than the minimum distance may be too far away to show drawdown.
Anticipated boundary conditions (e.g., an impervious zone or a recharging river) also can affect the
placement of observation wells. Wells can be placed to either minimize the effect of the boundary
or more precisely locate the discontinuity (Dawson and Istok, 1991). According to Walton (1987),
to minimize the effect of the boundary on distance-drawdown data, wells should be placed along
a line through the pumping well and parallel to the boundary. Observation wells also should be

4-16
placed on a line perpendicular to the boundary. If more than one boundary is suspected or known,
the wells should be located so that the effects on drawdown data encountered by the first boundary
have stabilized prior to encountering the second boundary (Sevee, 1991).
4.4 (A) Flow to a fully penetrating well. (B) Flow to a partially penetrating well. (Source:
Analysisand Evaluation of Pumping Test by G. P. Kruseman and N.A. de Ridder, Copyright © 1991
by International Institute for Land Reclamation and Improvement, publication 47, 377 pp. Printed
with permission).
Duration of Pumping
It is difficult to predict how long a pumping test should be conducted. The duration depends on the
hydrogeologicsetting,boundaryconditions,anddegreeofaccuracydesired. Economicfactorsand
time constraints also may be influential; however, economizing the period of pumping is not
recommended. The cost of continuing a test is low compared to total costs, particularly when the
wells have beenspecially constructed and positioned for test purposes (Kruseman and de Ridder,
1991).
Pumping tests commonly last from five hours to five days (Walton, 1962). Though not absolutely
necessary, it is recommended that tests be continued until the cone of depression has stabilized
and does not expand as pumping continues. Such a steady state or equilibrium can occur within
a few hours to weeks or never. According to Kruseman and de Ridder (1991), the average time to
reach steady state in leaky aquifers is 15 to 20 hours. A test of a confined aquifer should last a
minimum of 24 hours. Three days or more should be allowed for tests conducted in unconfined
aquifers because of the slow expansion of the cone of depression. The duration necessary to
define the hydraulic parameters depends on the regional and local geologic/hydrogeologic setting.
Plotting drawdown data during tests often reveals anomalies and the presence of suspected or
unknown boundaries, and assists in determining test duration.

4-17
Discharge Rate Measurement
Variation in discharge rates produces aberrations in drawdown that are difficult to treat in data
analysis. Engines, even those equipped with automatic speed controls, can produce variations up
to 20 to 25 percent over the course of a day. The rate should never vary by more than five percent
(Osborn, 1993). In order to obtain reliable data, discharge should be monitored and adjustments
made as needed.
The frequency of measurements is dependent on the pump, engine power characteristics, the well,
and the zone tested. Discharge from electric pumps should be measured and adjusted (if
necessary) at 5, 10, 20, 30, 60 minutes, and hourly thereafter. Other types of pumps may require
more frequent attention; however, no "rule of thumb" can be set because of the wide variation in
equipment response (Stallman, 1983).
Discharge Measuring Devices
Some discharge measurement techniques are more accurate than others and some allow for a
convenient means of adjusting rate. A commercial water meter of appropriate capacity can be
utilized. It should be connected to the discharge pipe in a way that ensures accurate readings. A
disadvantage is the unavoidable delay in obtaining values at the start of the test, when pumping rate
is being adjusted to the desired level (Driscoll, 1986). When discharge is low, the rate can be
measured as a function of time to fill acontainer of known volume. Theorifice weir is commonly
used to measure discharge from high capacity pumps. A manometer is fitted into the discharge
pipe. The water level in the manometer represents the pressure in the pipe when the water flows
throughthe orifice. Figure 4.5 shows a diagram of a typical circular orifice weir. Details on orifice
design and interpretation of results can be found in Driscoll (1986). Finally, discharge rate can be
obtained by water level measurements taken from weirs and flumes. The rate of flow is
determined within known constriction dimensions placed in the discharge channel originating at the
well head (Driscoll, 1986).
Interval of Water Level Measurements
Pretest Measurements
Prior to the start of tests, water level data should be collected from the pumping and observation
wells to determine existing trends for all zones to be monitored. The pumping phase should begin
onlyif identified and recorded trends are expected to remain constant. As a general rule, the period
ofobservation should be at least twice the length of the estimated time of pumping (Stallman, 1983).
Water levels should be measured and recorded hourly for all zones. In addition, the barometric
pressure should be monitored, at least hourly, to determine the barometric efficiency of saturated
zone(s), which may be useful in correcting the drawdown data. Barometric efficiency is discussed
later in this chapter.

4-18
Figure 4.5 Construction diagram of a circular orifice weir commonly used for measuring
rates of a high capacity pump. (Source: Ground Water and Wells by E.G. Driscoll.
Copyright , © 1986; Johnson screens. Printed with permission).
Measurements During Pumping
The appropriate time interval for water level measurements varies from frequent at the beginning
of a test, when water-levels are changing rapidly, to long at the end of the test, when change is slow.
Typical intervals for the pumping well and observation wells located close to the pumping well are
given in Tables 4.4 and 4.5, respectively. Though specified intervals need not be followed rigidly,
each logarithmic cycle of time should contain at least 10 data points spread through the cycle
(Stallman, 1983). Frequent readings are essential during the first hour since the rate of change is
faster. For wells further away and those located in zones above or below the pumping zone, the
frequent measurements recommended by Table 4.5 for the first few minutes of the pumping tests
are less important (Kruseman and de Ridder, 1991).

4-19
Table 4.4 Range of interval between water-level measurements in the pumping well
(Kruseman and de Ridder, 1991).
TIME SINCE START OF PUMPING TIME INTERVAL
0 to 5 minutes 0.5 minutes
2 to 60 minutes 5 minutes
60 to 120 minutes 20 minutes
120 to shutdown of the pump 60 minutes
Table 4.5 Range of intervals between water-level measurements in observation wells
(Kruseman and de Ridder, 1991).
TIME SINCE START OF PUMPING TIME INTERVAL
0 to 2 minutes
2 to 5 minutes
5 to 15 minutes
50 to 100 minutes
100 minutes to 5 hours
5 hours to 48 hours
48 hours to 6 days
6 days to shutdown of the pump
approx. 10 seconds
30 seconds
1 minute
5 minutes
30 minutes
60 minutes
3 times a day
1 time a day
According to Stallman (1983), it is not necessary to measure water levels in all wells simultaneously,
but it is highly desirable to achieve nearly uniform separation of plotted drawdowns on a logarithmic
scale. All watches used should be synchronized before the test is started, and provisions made to
notify all participants at the instant the test is initiated.
Measurements During Recovery
After pumping is completed, water level recovery should be monitored with the same frequency
used during pumping.
Water Level Measurement Devices
The most accurate recording of water level changes is made with fully automatic microcomputer-
controlled systems that use pressure or acoustic transducers for continuous measurements. Water
levels can also be determined by hand, but the instant of each reading must be recorded with a
chronometer. Measurements can be performed with floating steel tape equipped with a standard
pointer, electronic sounder, or wet-tape method. For observation wells close to the pumped well,
automatic recorders programmed for frequent measurements are most convenient because water
level change is rapid during the first hour of the test. For detailed descriptions of automatic
recorders, mechanical and electric sounders, and other tools, see Driscoll (1986), Dalton et al.
(1991), and ASTM D4750-87 (1992). Chapter 10 of this document contains a summary of manual
devices.

4-20
The measurement procedure should be standardized and calibrated prior to the start of the test.
Transducers should be calibrated by a direct method, and the calibration should be checked at the
conclusion of the recovery test.
Discharge of Pumped Water
Water extracted during a pumping test must be discharged properly and in accordance with any
applicable laws and regulations. At sites with contaminated ground water, the discharge may need
to be containerized and sampled to assess the presence of contaminants and, if necessary, treated
and/or disposed at an appropriate permitted facility.
It is not the intent of this document to define Agency policy on disposal of pumped water. In general,
the water should be evaluated to determine if it is characteristically a waste. If the ground water has
been contaminated by a listed hazardous waste, the ground water is considered to "contain" that
waste,and must therefore be managed as such. Disposal must be at a permitted hazardous waste
facility. Treatment must be in a wastewater treatment system that is appropriate for the waste and
meets the definitions contained in OAC rule 3745-50-10.
If containerization is not necessary, then pumped water must be discharged in a manner that
prevents recharge into any zone being monitored during the test. At a minimum, the water should
be discharged 100 to 200 meters from the pumped well. This is particularly important when testing
unconfined zones. At no time should the discharge water be injected back into the subsurface. A
permit for discharge via stream or storm sewer may be required (contact the Division of Surface
Water, Ohio EPA).
Decontamination of Equipment
Decontamination of equipment is important throughout an in-situ test. Contact of contaminated
equipment with ground water (or a well) may cause a measuring point to be unsuitable for water
quality investigations. Details on appropriate methods can be found in Chapter 10.
CORRECTION TO DRAWDOWN DATA
Prior to using the drawdown data collected from a pumping test, it may be necessary to correct for
either external sources or effects induced by the test. Barometric pressure changes, tidal or river
fluctuations, natural recharge and discharge, and unique situations (e.g., a heavy rainfall) may all
exert an influence. In confined and leaky aquifers, changes in hydraulic head may be due to
influences of tidal or river-level fluctuations, surface loading, or changes in atmospheric pressure.
Diurnal fluctuations in water levels can occur in unconfined aquifers due to the differences between
night and day evapotranspiration. Corrections to measurements may be needed for unconfined
aquifer data due to a decrease in saturated thickness caused by the pumping test. Also,
corrections may be necessary if the pumping well only partially penetrates the zone tested. By
identifying pre-test water level trends in zone(s) of interest, long and short-term variations can be
eliminated from the data if their impacts are significant during the pumping phase (Figure 4.6).

4-21
In order to determine if corrections are necessary, measurements should be taken during the test
inobservation wells unaffected by the pumping. Hydrographs of the pumping and observation wells
covering a sufficient period of pre-test and post-recovery periods can help determine if the data
needs to be corrected and also to correct the drawdown data. If the same constant water level is
observed during the pre-testing and post-recovery periods, it can safely be assumed that no
external events exerted an influence (Kruseman and de Ridder, 1991).
Figure 4.6 Hydrograph for hypothetical observation well showing definition of drawdown
(adapted from Stallman, 1983).

4-22
BE '
Mh
Mka / ãw
x 100%
Barometric Pressure
Data for confined and leaky zones needs to be corrected for the amount of rise in water levels
resulting from a decrease in atmospheric pressure and/or the amount of fall resulting from an
increase. To make the correction, the barometric efficiency (BE) of the zone needs to be
determined. The BE can be calculated by the following equation [Dawson and Istok (1991) and
Kruseman and de Ridder (1991)]:
where: Mh = change of head in the observation well.
(Mka/Õw) = change in atmospheric pressure expressed as a height of water.
ka = change in atmospheric pressure.
Õw = specific weight of water.
If the change in hydraulic head is plotted versus the change in pressure (measured column height)
and a best-fit straight line is drawn, then the slope of the line is the BE. From changes in
atmospheric pressure observed during the test and the BE, the change in water level due to
changes in barometric pressure can be calculated and the drawdown data can be corrected. When
artesian zones are tested, barometric pressure (to a sensitivity of +/- 0.01 inch of mercury) should
be recorded continuously throughout the testing period. Barometric efficiency typically ranges
between 0.20 and 0.75 (Kruseman and de Ridder, 1991).
Saturated Thickness
The saturated thickness of an unconfined zone decreases during pumping tests; however, most
conceptualmodels are based on the assumption that it remains constant. This assumption can be
accepted if the saturated thickness does not decrease more than 25 percent. If the decrease is
greater then 25 percent, then the drawdown data should be corrected prior to analysis (Dawson and
Istok, 1991).
According to Jacob (1944), data for unconfined zones can be corrected for saturated thickness
change with the following equation:
scorrected = s - s2
/2m
where: scorrected = corrected drawdown.
s = observed drawdown.
m = initial saturated thickness.
However, this correction is based on the Dupuit-Forchheimer assumption (ground water flows
horizontally and hydraulic gradient is equal to the slope of the water table). Neuman (1975) showed
that this assumption is not valid for an unconfined aquifer until the later portion of the test when the
drawdown matches the Theis type curve. Therefore, the correction is not recommended with early
and intermediate data (Dawson and Istok, 1991).

4-23
Unique Fluctuations
Data cannot be corrected for unique events such as a heavy rain or sudden fall or rise of a nearby
river that is hydraulically connected to the zone tested. However, in favorable circumstances, some
allowances can be made for the resulting fluctuations by extrapolating data from a controlled
piezometer outside the zone of influence. In most cases, the data collected is rendered worthless
and the test has to be repeated when the situation returns to normal (Kruseman and de Ridder,
1991). It is also important to understand the effects of nearby industrial or municipal pumping wells
prior to conducting a pumping test.
Partially-Penetrating Wells
In some cases, a saturated zone is so thick that it is not justifiable to install a fully-penetrating well,
and the aquifer must be pumped by a partially-penetrating well. Partial-penetration causes vertical
flow in the vicinity of the well, which results in additional head loss. As indicated earlier, this effect
decreases with increasing distance from the pumping well and no correction is necessary if the
observationwell is at a distance greater than 1.5 D/KH/KV. Variousmethodshavebeendeveloped
to correct data for the effects of partially-penetrating wells. These were discussed in detail by
Kruseman and de Ridder (1991). Table 4.6 lists the methods and their general applications.
ANALYSIS OF MULTIPLE WELL PUMPING TEST DATA
Many conceptual models exist for interpreting multiple well pumping test data. The hydraulic
properties computed by a particular method can only be considered correct if the assumptions
included in the conceptual model on which the method is based are valid for the particular system
being tested. Because the computed values depend on the choice of conceptual model used to
analyze the data, the selection of an appropriate model is the single most important step in analysis
(Dawson and Istok, 1991).
IIt is beyond the scope of this document to detail or discuss all conceptual models. Tables 4.7
through 4.11 can be used for a preliminary selection. In addition, the ASTM Method D4043-91
(1992) provides a decision tree for the selection of an aquifer test method and ASTM Methods
D4106-91 (1992) and D4105-91 (1992) offer information on determining hydraulic parameters.
Additional references are provided inthe tables that should serve as a guide for choice and use of
conceptualmodels. It should be noted that additional models may exist that are not listed here. Any
model utilized must be shown to be appropriate for site conditions.
Data collected during a pumping test are subject to a variety of circumstances that may be
recognized in the field or may not be apparent until data analysis has begun. In either case, all
information (including field observations) must be examined during data correlation and analysis.

4-24
Table 4.6 Corrections for partially penetrating effects (information derived from
Kruseman & de Ridder, 1991.)
METHOD APPLICATION ORIGINAL SOURCE
Huisman Method I - confined aquifer
- steady state
Anonymous, 1964
Huisman Method II - confined
- unsteady state
- time of pumping relatively
short
Hantush (1961 a, 1961 b)
Hantush Modification of
Theis Method
- confined
- unsteady state
short
Hantush (1961 a, 1961 b)
Hantush, Modification of
Jacob Method
- confined
- unsteady state
long
Hantush (1961 b)
Weeks', "Modification of
Walton and the Hantush
Curve Fitting Methods"
- leaky aquifers
- steady state flow
Weeks (1969)
Streltsova's Curve
Fitting Method
- unconfined
- anisotropic
- unsteady state
Streltsova (1974)
Neuman's Curve-Fitting
Method
- unconfined
- anisotropic
Neuman (1974, 1975,
1979)
RECOVERY TESTS
Recovery tests (also called residual drawdown tests) involve measuring water level rise after the
pump is shut down. These tests provide an independent check on the transmissivity determined
from a pumping test. Results of a recovery test conducted on confined and leaky confined zones
can be more reliable than pumping test results because recovery occurs at a constant rate that is
not influenced by the erratic fluctuations that can be characteristic of pumping rate. Hysteresis
effects must be accounted for when evaluating recovery data collected from unconfined aquifers.
Table 4.12 provides methods for analyzing recovery data.

Table 4.7 Multiple-Well, Constant Discharge Pumping Tests, Unconfined Aquifer.
GENERAL ASSUMPTIONS
1. The aquifer is unconfined. The aquifer is bounded below by an aquiclude.
2. All layers are horizontal and extend infinitely in the radial extent.
3. The aquifer is homogeneous, isotropic (unless noted) and of uniform thickness over the area influenced by the test.
4. Prior to pumping, the water table is horizontal over the area that will be influenced by the test.
7. Head losses through well screen and pump intake are negligible.
8. The aquifer is compressible and completely elastic.
9. The aquifer has been pumped long enough that equalibrium has been reached (drawdown is not changing with time).
10. Drawdown is small compared to the saturated thickness of the aquifer (i.e., no more than 25 percent).
11. Pumping and observation wells are screened over the entire saturated thickness and receives water from the entire aquifer (unless noted).
12. Ground water flow above the water table is negligible.
CAN ACCOUNT FOR
METHOD
Flow
Conditions
Partial
Penetration Other
ADDITIONAL ASSUMPTIONS
AND CONDITIONS
ANALYSIS/
PROCEDURES
REMARKS
Neuman's
Curve Fitting
Method
(Neuman,
1972)
(a,b) Transient No
anisotropic
conditions
The influence of the unsaturated
zone upon drawdowns of the
aquifer is negligible
The diameters of the pumped
and observation wells are small,
i.e., storage in them can be
neglected
The ratio of the specific yield
versus the elastic early-time
storativity is greater than 10,
i.e.,
Sy
SA
> 10
Curve fitting method Theory should be valid for
piezometers with short screens
provided that the drawdowns are
averaged over the aquifer (Van
der Kamp, 1985)

Table 4.7 (continued). Multiple-well, constant discharge pumping tests, unconfined aquifers.
CAN ACCOUNT FOR
METHOD
Flow
Conditions
Partial
Penetration Other
ADDITIONAL ASSUMPTIONS
AND CONDITIONS
ANALYSIS/
PROCEDURES
REMARKS
t>
2.5x10& 3
r
2
c
Ô
r> 3 00& rw
Thiem-
Dupuit's
Method,
(Thiem, 1906)
(b)
Steady
state No
Velocity of flow is proportional
to the tangent of the hydraulic
gradient instead of the sine as it
is in reality
Flow is horizontal and uniform
everywhere in a vertical section
through the well axis
The aquifer has been pumping
long enough that equilibrium
has been reached
Plot drawdown versus
time and substitute
values into analytical
equations
Steady state will only be
achieved after long pumping
time
Does not give accurate
description of drawdown near
the well
Assumptions ignore the
existence of a seepage face at
the well and the influence of the
vertical velocity component
Boulton and
Streltsova
(1976)
a
Transient Yes storage in
the well
Anisotropy
Type curve fitting The affects of well storage on
drawdown can be neglected if
either
or
Other models may be more
applicable.
Neuman
(1974) a
Transient Yes Anisotropy Type curve fitting
a Described in Dawson and Istok, 1991
b Described in Kruseman and de Ridder, 1991
t = time, Ô= transmissivity, r = radial distance from the pumping well, rw = effective radius of the pumping well, rc= inside radius of the pumping well within the range
of water fluctuations

Table 4.8 Multiple-well, constant-discharge pumping tests, confined aquifers.
GENERAL ASSUMPTIONS
1. The aquifer is confined. The aquifer is bounded above and below by aquicludes.
2. The aquifer is homogeneous, isotropic (unless noted in special conditions) and of uniform thickness over the area influenced by the test.
3. All layers are horizontal and extend infinitely in the radial extent.
4. Prior to pumping, the piezometric surface is horizontal and extends infinitely in the radial direction.
6. Ground water can be described by Darcy's Law.
7. Head losses through well screen and pump intake are negligible.
8. Ground water flow is horizontal and is directed radially to the well.
9. Pumping well and observation wells are screened over the entire thickness of the aquifer.
Additional assumptions for unsteady state flow.
10. The water removed from storage is discharged instantaneously with decline of head.
11. The diameter of the well is small, i.e., the storage in the well can be neglected.
APPLICATION
METHOD Flow
Condition
CAN ACCOUNT FOR ADDITIONAL ASSUMPTIONS
AND CONDITIONS
ANALYSIS/
PROCEDURES
REMARKS
Partial
Penetration
Other
Thiem (1906)
(a, b) Steady
state No
The aquifer has been pumped
long enough that equilibrium has
been reached (drawdown is not
changed with time)
Drawdown versus time
plotted on semi-log paper
and substitution of values
into analytical equations.
Equation should be used with
caution and only when other
methods cannot be applied
Drawdown is influenced by well
losses, screen and pump intake
Theis (1935)
(a,b) Transient No
The aquifer is compressible and
completely elastic
Type curve analysis Because there may be a time
lag between pressure decline
and release of stored water,
early drawdown data may not
closely represent theoretical
drawdown data
Hantush
(1964)
(b)
Transient Yes
Anisotropy in
the horizontal
plane
No vertical flow at the top and
bottom of the aquifer
Solutions involve type
curve analysis or
inflection point method
Inflection point method can be
used when the horizontal and
vertical hydraulic conductivities
can be reasonably estimated.

Table 4.8 (continued): Multiple-well tests, constant discharge pumping tests, confined aquifers.
APPLICATION
METHOD Flow
Condition
AND CONDITIONS
ANALYSIS/
PROCEDURES
REMARKS
Partial
Penetration
Other
Jacob's
Method
(Cooper and
Jacob, 1946)
(b)
Transient No
u < 0.01 where
u ' r2 S
4KDt
Based on Theis
Equation, straight line
method based on
drawdown versus time on
semi-log paper
Can also be applied to single
well pump tests
Condition that u values are
small usually is satisfied at
moderate distances from the
well within a hour or so.
at u < 0.05 or 0.10, error
introduced is 2 and 5%
respectively
Weeks
(1969)
(b)
Transient Yes
Anisotropy in
the vertical
plane
t >
SD
2Kv
Must have at least two
piezometers, one which is at a
distance of at least
r > 2D
Kh
Kv
Apply methods for fully
penetrating wells to
determine T and S, then
determine Kh & Kv by
data plots and
substitutions into
equations
Similar procedure can be
applied to leaky aquifers
Papadopulos
(1965)
(a)
Transient No
Anisotropy in
horizontal
plane
Curve fitting Two dimensional coordinate
system
Min. of three observation wells
Papadopulos
and Cooper
(1967)
(a)
Transient No Well Storage
Curve fitting Pumping rate is the sum of the
ground water entering in the
pumping well from the aquifer
and the rate of decrease of
water stored in well casing.

APPLICATION
METHOD Flow
Condition
AND CONDITIONS
ANALYSIS/
PROCEDURES
REMARKS
Partial
Penetration
Other
Neuman's
Extension of
Papadopulos
(Neuman et
al., 1984)
(b)
Transient No
Anisotropy in
the horizontal
plane
Aquifer is penetrated by at least
three wells, which are not on the
same ray.
Requires drawdown data
from at least 3 wells on
different rays from the
pumping well
Requires two pumping
tests conducted in
sequence
More reliable results can be
obtained by conducting 3
pumping tests.
Hantush
(1966)
(b)
Transient No
Anisotropy in
the horizontal
plane
Use of Theis (1906) or
Cooper and Jacob (1946)
Substitution into various
equations
If the principal direction of
anisotropy is known, drawdown
data from two piezometers on
different rays is sufficient. If
not, 3 wells on different rays will
be needed.
Hantush and
Thomas
(1966)
(b)
Transient No
Anisotropy in
the horizontal
plane
Apply methods for
confined isotropic
aquifers to the data for
each ray of piezometers
Calculation of T in the
major and minor
directions of anisotropy
involves substitution
a Described in Dawson and Istok (1991)
b Described in Kruseman and de Ridder (1991)
S = Storativity, K = hydraulic conductivity, D = thickness of saturated zone, r = distance to observation well, t = time since start of pumping

Table 4.9 Multiple-well, Constant discharge pumping tests, leaky aquifers.
GENERAL ASSUMPTIONS
1. The aquifer is leaky.
2. The aquifer and aquitard have seemingly infinite and areal extent.
3. The aquifer and aquitard are homogeneous, isotropic (unless noted), and of uniform thickness over the area influenced by the test.
4. Prior to pumping, the piezometric surface and the water table are horizontal over the area that will be influenced by the test.
5. The well penetrates the entire thickness of the aquifer and thus receives water by horizontal flow (unless noted).
6. The flow in the aquitard is vertical.
7. The drawdown in the unpumped aquifer (or aquitard) is negligible.
Additional assumptions for transient conditions:
9.Water removed from storage in the aquifer and the water supplied by leakage from the aquitard is discharged instantaneously with decline of head.
10. The diameter of the well is very small, i.e., the storage in the well can be neglected.
CAN ACCOUNT FOR
METHOD
Flow
Conditions
Partial
Penetration
Other ADDITIONAL
ASSUMPTIONS AND
CONDITIONS
ANALYSIS/PROCEDU
RES
REMARKS
DeGlee (1930 &
1951)
(b)
steady
state
No
L > 3D: where L
represents a leakage
factor and D is the
saturated thickness of
the aquifer
Substitution into
equations
Hantush (1960)
(b)
Transient No
Takes into account
storage changes in
the aquitard
The aquitard is
compressible, i.e., the
changes in the aquitard
storage are appreciable
t < S ) D)
10K )
Type curve analysis
Generally is Theis
equation plus an error
function
Only the early-time
drawdown should be
used to satisfy the
assumption that the
drawdown in the
aquitard is negligible

Table 4.9 (continued): Multiple-well, constant discharge pumping tests, leaking aquifers.
CAN ACCOUNT FOR
METHOD
Flow
Conditions
Partial
Penetration
Other ADDITIONAL
ASSUMPTIONS AND
CONDITIONS
ANALYSIS/PROCEDU
RES
REMARKS
Hantush-Inflection
Point (1956) (a,b)
Transient No
The aquitard is
incompressible, i.e.,
changes in aquitard
storage are negligible
It must be possible to
extrapolate the steady-
state drawdown for each
observation well
Plotting drawdown
versus time on semi-
log paper, substitution
of values into equation
Accuracy depends on
accuracy of
extrapolating the
maximum drawdown
Two different methods,
one requires one
piezometer, and the
other requires data
from two piezometers
Hantush-Jacob
(1955) (b)
Steady
state
No
aquitard is
incompressible
L > 3D
r/L # 0.05
L = leakage factor
r = distance from
pumping well
D = saturated
thickness of aquifer
Best fit straight line,
substitution into
equation
Results are an
approximation
because method only
can be used for values
of r/L < 0.05 which is a
restrictive limiting
condition
If errors in hydraulic
parameters are to be
less than 7%, r/L
should be less than
0.16
Lai and Su (1974)
(a,b) Transient No
The aquitard is
changes in aquitard
Type - curve fitting
method

CAN ACCOUNT FOR
METHOD
Flow
Conditions
Partial
Penetration
Other ADDITIONAL
ASSUMPTIONS AND
CONDITIONS
ANALYSIS/PROCEDU
RES
REMARKS
t <
S )
(D)
)2
10DK )
Neuman-
Witherspoon (1972)
(b)
Transient No
Determines the
hydraulic
characteristics of
the aquitard
The aquitard is
compressible i.e.,
changes in aquitard
storage are appreciable
The radial distance from
the well to the piezometer
should be small (<100m)
Substitution of values
into Neuman
Witherspoon equations
(derived from Hantush-
Jacob Equation)
Need to calculate for
transmissivity using
one of the other
methods for leaky
aquifers
Hantush-Jacob
(1955)
(a)
Transient No
Ground water flow in the
aquitard is vertical
Aquifer is bounded above
by aquitard and an
unconfined aquifer and
bounded below by an
aquiclude
Curve fitting and
substitution of values
into equation
Drawdown in the
source bed can be
neglected when
or
KD of source bed is
>100 KD of aquifer
Walton (1962)
(b)
Transient No
- The aquitard is
changes in aquitard
- Type curve fitting - To obtain the unique
fitting position of the
data plot with one of
the type curves,
enough of the
observation data
should fall within the
period when leakage
effects are negligible

CAN ACCOUNT FOR
METHOD
Flow
Conditions
Partial
Penetration
Other ADDITIONAL
ASSUMPTIONS AND
CONDITIONS
ANALYSIS/PROCEDU
RES
REMARKS
4-33
t >
SD
2Kv
Hantush (1966)
(b) Transient No
Anisotropic in
horizontal plane
Substitution into
equations
- Similar to Hantush's
methods for confined
aquifers except initial
step uses methods
to calculate the
hydraulic parameters
Weeks (1969) (b)
Transient Yes
Anisotropic in the
vertical plane
- Large values of
pumping time:
- Drawdown data from at
least two piezometers,
with one piezometer at
a distance greater than
2D
Kh
Kv
-Aquitard is
incompressible
- Apply methods for
leaky confined
aquifers, to determine
transmissivity and
storativity, then
determine Kh and Kv
from data plots and
substitutions into
equations
- Similar process can
be conducted for
confined aquifer
a Described in Dawson and Istok, 1991
b Described in Kruseman and de Ridder, 1991
t = time since start of pumping, S' = aquitard storativity, D'= saturated thickness of aquitard, D = saturated thickness of the aquifer, K'= hydrualic conductivity of
aquitard

Table 4.10 Pumping tests, variable discharge.
METHOD* APPLICATION ASSUMPTIONS PROCEDURE REMARKS
Birsoy and Summers
(1980)
-Confined
- Transient
- Aquifer pumped step-
wise or intermittently at
variable rates
- General assumptions for confined
aquifers
r S
KD B t tt n n
2
4
1
0 01×
−
<
( )( )
.
Analytical solution
Apply the principle of
superposition to Jacob’s
approximation rates
Tedious process
Aron and Scott (1965) -Confined
-Transient
Discharge rate decreases
- Same general assumptions as
above
- Discharge rate deceases with
time sharpest decrease occurring
soon after the start of pumping
Curve fitting and analytical
solutions
Analogous to the Jacob
Method
Hantush (1964) - Confined
- Transient
- Standard assumptions for
confined aquifers
- At the start of the tests, the water
level in the free flowing well drops
instantaneously. At t> 0
drawdown is constant and its
discharge rate is variable
- Type curve analysis
Hantush-DeGlee
Method (Hantush,
1959b)
- Leaky aquifers
- Transient
- Fully penetrating well
- Standard assumptions for leaky
aquifers (see leaky section)
- L > 3D
- At the start of the tests, the water
level in the free flowing well drops
instantaneously. At t >0
drawdown is constant and its
discharge rate is variable
DeGlee’s method using
Hantush Equation
* Methods described in Kruseman and de Ridder (1991).
R = distance of piezometer from pumping well, S = storativity, D = thickness of aquifer, K = hydraulic conductivity, B u(n) is a time function, and L = leakage
factor

2
Methods are described in Kruseman and de Ridder, 1991.
4-35
Table 4.11 Methods of analysis for pumping tests with special conditions.
CONDITION FLOW
AQUIFER
TYPE
MODELS &
SOURCES2
One or more recharge boundaries Steady State Confined or
Unconfined
Dietz (1943)
One or more straight recharge
boundaries
Unsteady
State
Confined or
Unconfined
Stallman (in Ferris et
al., 1962)
One recharge boundary Unsteady
State
Confined or
Unconfined
Hantush (1959a)
Aquifer bounded by two fully
penetrating boundaries
Unsteady
State
Leaky or
Confined
Vandenberg (1976
and 1977)
Wedge shaped aquifer Unsteady
State
Confined Hantush (1962)
Water table slopes
Steady State Unconfined Culmination Point
Method (Huisman,
1972)
Unsteady
State
Unconfined Hantush (1964)
Two layered aquifer, unrestricted
cross flow
Pumping well does not penetrate
entire thickness
Unsteady
State
Confined Javandel-Witherspoon
(1983)
Leaky two-layered aquifer,
separated by aquitard with cross-
flow across aquitard
Steady State Leaky Bruggeman (1966)
Large diameter well Unsteady
State
Confined Papadopulos (1967),
Papadopulos and
Cooper (1967)
Large diameter well Unsteady
State
Unconfined Boulton and
Streltsova, (1976)

4-36
Table 4.12 Recovery test methods (discussed in Kruseman and de Ridder, 1991).
METHOD APPLICATION SOURCE
Theis Recovery
Methods
C Confined
C Unsteady state
C Recovery after constant discharge
C Theis (1935)
C Leaky
C Unsteady state
C Vandenberg (1975)
C Hantush (1964)
C Unconfined
C Late recovery data
C Neuman (1975)
C Unconfined
C Recovery after constant drawdown
C Rushton and Rathod
(1980)
Birsoy and Summers C Unconfined
C Recovery after variable discharge
C Birsoy and Summers
(1980)
PRESENTATION OF DATA
The specifics of an in-situ test should be described in a report to demonstrate that the test was
conductedproperlyandthatthedataandinterpretationsarerepresentativeofsiteconditions. Work
plans should be submitted prior to conducting tests to ensure that the results will be relevant to
regulatory and program goals.
SINGLE WELL TESTS
At a minimum, the following should be specified in a workplan for a single well or slug test:
• Preliminary evaluation of hydraulic conductivity (i.e., data used to plan the test).
• Design or proposed design of the well (e.g., depth and length of screen and filter pack).
• Proposed amount and method to displace the water, such as:
-Dimension and weight of slug.
-Composition of slug.
-Manner in which the slug will be lowered and raised from the well.
-Use of packers, and manner in which pressure will be delivered to packed-off zone.
-Chemical quality of water to be added.
• Proposed frequency of water level measurements.
• Proposed number and location of tests.
• Proposed method of analysis.

4-37
To provide adequate documentation that the test was conducted and interpreted correctly, the
following should be provided in a report:
• The design and implementation of the test (workplan content items as specified above).
• All raw data (including type curves, if used).
• Sample calculations.
• Any field conditions or problems noted during the test that may influence the results.
• An evaluation and interpretation of the data (relating it to overall site conditions).
MULTIPLE WELL PUMPING TESTS
At a minimum, the following should be provided in a workplan for a conventional multiple well
pumping test:
• Preliminary evaluation of hydrogeologic conditions, including all data used to plan and design
the test.
• Proposed test and rationale for design, including but not limited to:
- Geologic zone into which the pumping well is completed (i.e. areal extent, thickness,
lateral and vertical extent).
- Pumping well construction (justification should be provided if the well screen is partially
penetrating).
- Duration of pumping.
- Rate of pumping and method for determination.
- Location of all proposed observation wells.
- Geologic zone(s) to be monitored (including depths, thickness, spatial relationship to the
pumped zone).
- Observation well construction.
- Method of water level measurements (for each well).
- Methods for gathering data used to correct drawdown and establishment of existing
trends in water levels.
- Method of data analysis.
- Procedures for the discharge of pumped water.

4-38
After completion of a pumping test, the following should be included in a report to document that the
test was conducted and interpreted correctly:
• Specific design of the test (workplan content items as specified above), including
modifications from the planned configuration and rationale for any deviations.
• Date and time pumping began and ended.
• Raw data, including water level measurements, time of measurement in minutes after
pumping started or ended, drawdown, pumping rates, etc. All data should be expressed
in consistent units.
• Data plots and type curves, if used. All graphs and data plots should be labeled clearly.
• Calculations.
• Comments noting any external events (e.g., change in weather patterns, passage of train
or heavy machinery).
• Data plots, graphs, and equations used to determine drawdown corrections.
• Data analysis method, including assumptions, limitations and references.
• Interpretationof the data using both results of the test and other available hydrogeologic
information.

4-39
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