-------
MATRIX NUMBER 27
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid permitted; casing diameter 4 to 8 inches; total
well depth greater than 150 feet.
\ ง8
\ *~ i
\ ^ ^"
\ < 5
\ *fc
>l fฃ jj
\ 2^
\ <"
\ * 11.
CHILLING \
METHODS \
Hand Auger
Driving
Jetting
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual WaH Rotary
Cable Tool
g
Q
C.
15
Ol
c
^
Versatility ol 0
NA
NA
NA
NA
NA
10
NA
NA
NA
8
>.
Sample Reliab
NA
NA
NA
NA
NA
jiS
O
O)
_c
O
1
1
CC
NA
NA
NA
NA
NA
8 10
NA NA
NA|| NA
NA
10
NA
6
c
ฃ
Q.
'5
CT
UJ
>ซ
o>
=
*
S
O ฃ
"*" Q.
o o
3*
C
3 >
Jo
Q CET3
Availability of
NA
NA
NA
NA
NA
10
NA
NA
NA
7
Relative Time
Installation an
NA
NA
NA
NA
NA
10
NA
NA
NA
4
o
>,
jsP ^
"5-2
c" *D
.ฎ .Q
01 IS
c 2
Ability of Drill
Preserve Natu
NA
NA
NA
NA
NA
6
NA
NA
NA
10
ป
E
ED
Q
C
cn
w
O
15
to
c
o
11
< 0
NA
NA
NA
NA
NA
8
NA
NA
NA
10
.2
ป
CL
O
(^
5
l~
o *
Relative Ease
and Developr
NA
NA
NA
NA
NA
4
NA
NA
NA
10
TOTAL
NA
NA
NA
NA
NA
66
NA
NA
NA
65
EXPLANATORY NOTES:
... ... , . , ,. . . ,. , , . ... , . . , . . . , . . . relatively isolated, saturated
1. Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual,
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g., dense, silt/clay) to servere (e.g., coarse gravel and boulders).
3. The anticipated use of the monitoring well permits the use of drilling fluid and additives in construction.
4. Diameter of borehole, and depth, eliminates most options.
193
-------
MATRIX NUMBER 28
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted, casing diameter 2 inches or
less; total well depth O to 15 feet.
z w
\ pฐ
\ 3t
\ 2s
\ fl
\CJ
DRILLING \
METHODS
\
Hand Auger
Driving
Jetting
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Tool
o
o
ฃ
21
O)
O
"5
;=
<3
'
4
7
NA
8
8
NA
5
9
10
NA
5
1
NA
10
10
NA
5
8
9
NA
1
Q
>
B
0)
CC
9
10
NA
10
10
NA
8
6
6
NA
c
|
'5
CT
UJ
O)
C
Q
5
ra
1
10
10
NA
9
9
NA
8
4
1
NA
=
5 c
o I
D 0
m
E 0>
Is
CC -o
p
h- O
ffl ^
- ซ
13 S
as o
cc -E
5
6
NA
10
10
NA
8
3
8
NA
o
?S
%ฃ
IS
^8
||
ll
0|
^. 1^
^ QJ
:= (/)
5 ฃ
>
* o
^ -o
ac i
6
4
NA
5
10
NA
4
10
10
NA
TOTAL
54
44
NA
70
75
NA
5 3
59
84
NA
EXPLANATORY NOTES:
1. Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. Jetting, mud rotary and cable tool methods would require the addition of fluid.
5. Air rotary with casing hammer requires driving 6-inch or greater diameter casing and completion by pullback
6. Air rotary, hand auger and solid-flight auger completion possible only if unsupported borehole is stable.
194
-------
MATRIX NUMBER 29
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted; casing diameter 2 inches or
less; total well depth 15 to 150 feet.
\ z w
\ 2ฐ
\ =t
\ ^S
\ IT 2
\ "" ฃ
\ Si Q
\ ff U.
\ C
\ฐ
DRILLING \
METHODS \
Hand Auger
Driving
Jetting
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Tool
-o
ฃ
5
D)
C
Q
"o
~
CO
_c
iS
0
Q>
.Z
s
DC
NA
7
NA
10
10
NA
8
6
6
NA
**
c
CD
Q.
ง
O)
=
S
"5
.^
3
ซ
I
NA
10
NA
10
10
NA
B
4
1
NA
=:
0>
?!
ฃ|
|f
OC 13
m C
E *"
P|
Q) '*-*
.5 =
ra c
0) O
H O
;= 3
"C "(5
QZ
o 9J
^ 0)
11
NA
5
NA
B
10
NA
7
9
9
NA
i_
QJ
(0
5
c
O)
'8
o
15
"55
-
o
^* Q)
s 5
< 0
NA
1
NA
9
9
NA
9
10
10
NA
c
0
0)
Q.
O
O
"S
- S
c
(0 O-
m o
UUa
4) >
^Q
1?
cc a
NA
4
NA
5
10
NA
4
10
10
NA
TOTAL
NA
35
NA
70
79
NA
56
63
64
NA
EXPLANATORY NOTES:
1. Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. Jetting, mud rotary and cable tool methods would require the addition of fluid.
5. Air rotary with casing hammer requires driving 6-inch or greater diameter casing and completion by pullback.
6. Air rotary and solid-flight auger completion possible only if unsupported borehole is stable.
195
-------
MATRIX NUMBER 30
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted; casing diameter 2 inches or
less; total well depth greater than 150 feet.
\ 1ง
\ *"" ?
\ 3*~
\ ซc z
\ 5 ฐ
\^ z
\ o 3
\ < **
V ^J
\ wft
\ E
DRILLING \
METHODS \
Hand Auger
Driving
Jetting
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Tool
o
o
ฃ1
"3
o>
.E
Q
"o
=
SO
v>
>
NA
NA
NA
NA
NA
NA
7
10
10
NA
>,
'ฃ
10
EC
ฃ
(8
C/3
NA
NA
NA
NA
NA
NA
7
9
10
NA
tป
o
O
O)
C
n
6
0>
I
NA
NA
NA
NA
NA
NA
10
8
B
NA
ซ>
c
D.
'3
a
m
c
a
"5
.is
s
(d
s
NA
NA
NA
NA
NA
NA
10
8
4
NA
gj
i
Q C
it
il
W ""
ฃE tj
? (5
ง C
t- 5
1 1
11
NA
NA
NA
NA
NA
NA
10
9
9
NA
o
~*
OS W
ll
"o C
* o
t-O
.fi
^E S
2^
i-l
:= &ซ
Sfi
NA
NA
NA
NA
NA
NA
7
9
10
NA
fe
V
1
5
c
o>
'to
Q
1
C
o
5-1
i?
< 0
NA
NA
NA
NA
NA
NA
10
10
10
NA
c
*2
"o.
O
o
"si
5 *-
ฐ1
OS On
ffl D
UJ "Sj
||
NA
NA
NA
NA
NA
NA
4
10
8
NA
TOTAL
NA
NA
NA
NA
NA
NA
65
73
69
NA
EXPLANATORY NOTES:
1. Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. The depth requirement and the decision not to utilize drilling fluid limit equipment options.
6. Jetting, mud rotary, and cable tool methods would require the addition of fluid.
6. Air rotary with casing hammer requires driving 6-inch or greater diameter casing and completion by pullback.
7. Air rotary completion possible only if unsupported borehole is stable.
196
-------
MATRIX NUMBER 31
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted: casing diameter 2 to 4 inches;
total well depth O to 15 feet.
z w
\ O
\ li
\ 0
\o
DRILLING
METHODS ^
Hand Auger
Driving
Jetting
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Tool
|
IS
o>
c
^
Versatility of D
NA
1
NA
8
10
NA
5
9
9
NA
t
Sample Reliab
NA
1
NA
10
10
N/
5
ฃ
c
N/
8
O
O>
Relative Drillin
1
MA
10
NA
10
1C
N/
I
(
I
N
1
Q.
'5
CT
UJ
o>
_c
6
Availability of
NA
10
NA
10
10
NA
8
4
1
NA
=
a>
?I
o E
If
is
C -o
Relative Time
Installation an
NA
5
NA
10
10
NA
8
6
6
NA
0
O) ซ
ซi
J=6
ฃ,3
i1!
Ability of Drill
Preserve Nati
NA
5
NA
8
10
NA
7
9
9
NA
oj
CO
D
c
.a>
CA
a>
O
"<5
Ability to Inst
of Well
NA
1
1
NA
7
9
NA
8
10
9
NA
c
o
ซ
a.
o
O
1^
o|
Relative Ease
and Developr
NA
4
NA
5
8
NA
"4
10
10
NA
TOTAL
NA
37
NA
68
77
NA
53
62
59
NA
^^^^^^M
EXPLANATORY NOTES:
... .. . . . , .. . . .. . . . with monitoring conducted in individual, relatively isolated, saturated
1, Unconsolidated formations, predominantly unsaturated, M |etionais in a saturated zone
zones. Drilling is through primarily unsaturated material,
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. Jetting, mud rotary and cable tool methods would require the addition of fluid.
5. Air rotary with casing hammer requires driving 8-inch or greater casing and completion by pullback.
6. Air rotary and solid-flight auger completion possible only if unsupported borehole is stable.
197
-------
MATRIX NUMBER 33
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted; casing diameter 2 to 4 inches;
total well depth greater than 150 feet,
NOQ
CO
ซE
3fc
So
rS
cc
S Q
jฃ
i!o
ฃ
j
DRILLING \
METHODS \
Hand Auger
Driving
Jetling
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Too)
o
o
^
^
O)
c
^
Q
,^
O
J=
03
i
NA
NA
NA
NA
NA
NA
5
9
10
NA
2
'
JD
03
'a>
cr
o>
o.
ซ
NA
NA
NA
NA
NA
NA
5
9
10
NA
ซ
0
O)
C
^
Q
5
_ง
cr
NA
NA
NA
NA
NA
NA
10
6
6
NA
c
I
Q.
'5
cr
LLJ
I
Q
"5
2
2
a
I
NA
NA
NA
NA
NA
NA
10
6
4
NA
:> ป-
> c
>_ a)
2. ฃ
~o o
2 'o
'5 >
CE T3
0) c
p ซ
c c
ง1
si
ป w
IT ฃ
NA
NA
NA
NA
NA
NA
10
8
10
NA
o
X
jfง
5 ^5
ai o
HO
c 2
S 3
ft Z
O 5
2 o>
= 31
S ff
< DL
NA
NA
NA
NA
NA
NA
5
10
10
NA
Q)
a>
E
ra
b
c
01
Q
2
en
C
*-
^* "gj
I!
< 0
NA
NA
NA
NA
NA
NA
10
to
10
NA
c
o
ป
"o.
E
o
0
5 ~
"ฎ c
tn Q~
to O
LU $
* 5
~ Q
EC a
NA
NA
NA
NA
NA
NA
5 .
10
10
NA
TOTAL
NA
NA
NA
NA
NA
NA
60
68
70
NA
EXPLANATORY NOTES:
1. Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. No drilling fluid, increasing depth and diameter requirements eliminate many options.
5. Air rotary with casing hammer requires driving 8-inch or greater casing and completion by pullback.
199
-------
MATRIX NUMBER 34
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted; casing diameter 4 to 8 inches;
total well depth O to 15 feet.
z w
\ 2ฐ
\ <ฃ
\ 1*
\ "2
\ E
\ ฎ -J
\ rf *
\ " O
\ DC
\ So
\ BE
\O
DRILLING \
METHODS \
Hand Auger
Driving
Jetting
Solid Flight
Auger
Hollow Stem
Auger
Mud Rotary
Air Rotary
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Tool
|
5
c
~
Q
"o
"
"in
I
NA
NA
NA
NA
NA
NA
6
10
NA
NA
>,
'a
CO
i
ID
a
1
NA
NA
NA
NA
NA
NA
5
10
NA
NA
"55
O
o
O)
c
-
o
CD
~
CO
0)
ฃE
NA
NA
NA
NA
NA
NA
10
6
NA
NA
^-
c
I
g.
cr
LU
.?
Q
B
.$
'ฃ
CO
1
NA
NA
NA
NA
NA
NA
10
6
NA
NA
IQ
(U fc
.
If
c. "6
ci> o
t-o
c 5
= 2
6z
"o ง
^ Q)
< i
NA
NA
NA
NA
NA
NA
6
10
NA
NA
V.
w
E
CO
6
c
O)
1
2
en
c
o
S* (U
< 0
NA
NA
NA
NA
NA
NA
6
10
NA
NA
c
g
'53
a.
o
O
=
5
o *
i e
ป a.
.S^
* S
~ Q
ฃ 5
NA
NA
NA
NA
NA
NA
5
10
NA
NA
TOTAL
NA
NA
NA
NA
NA
NA
58
71
NA
NA
EXPLANATORY NOTES:
1. Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones, Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. Diameter and no drilling fluid minimizes options
5. Jetting, mud rotary and cable tool methods would require the addition of fluid.
6. Air rotary with casing hammer requires driving 12-inch or greater diameter casing and completion by pullback.
7. Air rotary completion possible only if unsupported borehole is stable.
200
-------
MATRIX NUMBER 35
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted; casing diameter 4 to 8 inches;
total well depth 15 to 150 feet.
\ zซ
\ oo
\ *=ง
\ 3*-
\ < s
\ ^ /ซ5
\UJ Mp
c
Q
"o
JX
ซ5
1
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
>,
ฃ
^
a
V)
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
R
O
o
f
*ฃ
o
t
Relative
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
c
to
a
'5
tr
u
01
S
6
5
>*
s
AvaHabi
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
S) <-
5 c
s I
"Tj Q
^ "m
J"~
OC T3
O
h- O
Ol-s
c 2
:= 3
O 7
"7^ 33
ฐe
Is
B S?
< Q.
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
1
ซs
S
c
.S*
ffS
Q
15
tn
_ฃ
O
ll
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
e
-2
o.
E
o
y
15
0 ง
S I
TO O
Ul "gg
1!
ป c
NA
NA
NA
NA
NA
NA
10
NA'
NA
NA
TOT*
NA
NA
NA
NA
NA
NA
80
NA
NA
NA
EXPLANATORY NOTES:
1, Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders).
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. No drilling fluid, depth and diameter requirements have eliminated options.
5. Oversize drillpipe and/or auxiliary air probably required.
6. Jetting, mud rotary and cable tool methods would require the addition of fluid.
7. Air rotary completion possible only if unsupported borehole is stable.
8. Air rotary with casing hammer unlikely to penetrate to specified depths with 12-inch diameter outer casing that is required for 8-inch
diameter casing and screen completion.
9 If borehole is unstable, for 8-inch diameter casing there is no currently available method that can be used to fulfill the requirements
as stated above. Therefore, fluid would be necessary to install the well and invasion-permitting matrices will apply.
201
-------
MATRIX NUMBER 36
General Hydrogeologic Conditions & Well Design Requirements
Unconsolidated; unsaturated; invasion of formation by drilling fluid not permitted; casing diameter 4 to 8 inches;
total well depth greater than 150 feet.
\ go
\ *&
\ < s
\ Sz
\ *3
X C
^i "
"a.
I
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
_
o
O
o>
c
=
'C
D
I
C
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
"c
S3
O.
3
cr
01
C
o
o
=
15
ฃ
1
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
Jง
"5 ซ
Q- C
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
D
ag
1:1
o c
fli O
1-0
C ฎ
E D
,*_
O >
5* 9g
Is
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
5
|
Q
c
g>
s
2
1ft
c
o
^"55
< 0
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
c
g
a.
O
O
!ฃ
"o ^
^ Q.
Ed a
LU -^
^ *
Q
td ,_
ll
EH ฃ13
NA
NA
NA
NA
NA
NA
10
NA
NA
NA
TOTAL
NA
NA
NA
NA
NA
NA
80
NA
NA
NA
EXPLANATORY NOTES:
L Unconsolidated formations, predominantly unsaturated, with monitoring conducted in individual, relatively isolated, saturated
zones. Drilling is through primarily unsaturated material, but completion is in a saturated zone.
2. Borehole stability problems vary from slight (e.g. dense, silt/clay) to severe (e.g. coarse gravel and boulders),
3. The anticipated use of the monitoring well prohibits the use of drilling fluid and additives in construction.
4. No drilling fluid, depth and diameter requirements have eliminated options.
6. Oversize drillpipe and/or auxiliary air probably required.
6. Jetting, mud rotary and cable tool methods would require the addition of fluid.
7. Air rotary completion possible only if unsupported borehole is stable.
8. Air rotary with casing hammer unlikely to penetrate to specified depths with 12-inch diameter outer casing that is required for
8-inch diameter casing and screen completion.
9. If borehole is unstable, for 8-inch diameter casing there is no method that can be used to fulfill the requirements as stated above.
Therefore, fluid would be necessary to install the well and invasion-permitting matrices will apply.
202
-------
MATRIX NUMBER 37
General Hydrogeologic Conditions& Well Design Requirement
Consolidated; invasion of formation by drilling fluid permitted; casing diameter 4 inches or less.
Air Rotary with
Casing Hammer
Dual Wall Rotary
Cable Tool
EXPLANATORY NOTES:
1. Consolidated formations, all types
2. The anticipated use of the monitoring well permits the use of drilling fluid and additives in construction
3. Boreholes are expected to be sufficiently stable to permit open-hole completion.
4. Core sampling will improve the relative value of the mud rotary method.
5. Where dual-wall air is available it becomes an equally preferred method with air rotary.
203
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workability without compromising set strength;
and
7) diatomaceous earth. Diatomaceous earth reduces
slurry density, increases water demand and
thickening time and reduces set strength.
Water used to mix neat cement should be clean, freshwater
free of oil or other organic material and the total dissolved
mineral content should be less than 2000 parts per million. A
high sulfate content is particularly undesirable (Campbell and
Lehr, 1975). If too much water is used, the grout will be
weakened and excessive shrinkage will occur upon setting. If
this occurs, the annul us will not be completely tilled after the
grouting operation. The voids in the annulus may not be seen
from the surface but may still be present along the length of the
casing (Kurt, 1983).
Mixing of neat cement grout can be accomplished manu-
ally or with a mechanical mixer. Mixing must be continuous so
that the slurry can be emplaced without interruption. The grout
should be mixed to a relatively stiff consistency and immedi-
ately pumped into the annulus. The types of pumps suggested
for use with grout include reciprocating (piston) pumps, dia-
phragm pumps, centifugal pumps or moyno-typepumps. These
pumps are all commonly used by well drilling contractors.
Neat cement, because of its chemical nature (calcium
carbonate, alumina, silica, magnesia, ferric oxide and sulfur
trioxide), is a highly alkaline substance with a pH that typically
ranges from 10 to 12. This high pH presents the potential for
alteration of the pH of water with which it comes in contact.
This alteration of pH in the ground water can subsequently
affect the representativeness of any water-quality samples
collected from the well. Because the mixture is emplaced as a
slurry, the coarse materials that comprise the filter pack around
the intake portion of a monitoring well maybe infiltrated by the
cement if the cement is placed directly on top of the filter pack,
This is particularly true of thinner slurries that are mixed with
more than 6 gallons of water per sack of cement. The cement
infiltration problem also can be aggravated if well development
is attempted prior to the time at which the cement has reached
final set.
These problems can have a severe and persistent effect on
the performance of the monitoring well in terms of yield and
sample integrity. If thin grout is placed on top of the filter pack
and infiltrates, the cement material can plug the filter pack and/
or the well intake upon setting. The presence of the high-pH
cement within the filter pack can cause anomalous pH readings
in subsequent water samples taken from the well. Dunbar et al.
(1985) reported that wells completed in low-permeability geo-
logic materials with cement placed on top of the filter pack
consistently produced samples with a pH greater than 9 for two
and one-half years despite repeated attempts at well develop-
ment. For these reasons, neat cement should not be emplaced
directly on top of the filter pack of a monitoring well. Ramsey
and Maddox (1982) have suggested that a 1 to 2-foot thick very
fine-grained sand layer be placed atop the filter pack material
prior to emplacement of the neat cement grout to eliminate the
grout infiltration potential. A 2- to 5-foot thick bentonite seal
will accomplish the same purpose, but requires additional time
to allow the bentonite to hydrate prior to cement placement.
Either or both of these procedures serve to minimize well
performance impairment and chemical interference effects
caused by the proximity of neat cement to the well intake.
Another potential problem with the use of neat cement as
an annular sealing material centers around the heat generated by
the cement as it sets. When water is mixed with any type of
Portland cement, a series of spontaneous chemical hydration
reactions occur. If allowed to continue to completion, these
reactions transform the cement slurry into a rigid solid material.
As the hydration reactions progress and the cement cures, heat
is given off as a by-product this heat is known as the heat of
hydration (Troxell et al., 1968). The rate of dissipation of the
heat of hydration is a function of curing temperature, time,
cement chemical composition and the presence of chemical
additives (Lerch and Ford, 1948). General] y, the heat of hydra-
tion is of little concern. However, if large volumes of cement are
used or if the heat is not readily dissipated (as it is not in a
borehole because of the insulating properties of geologic ma-
terials), relatively large temperature rises may result (Verbeck
and Foster, 1950). The high heats can cause the structural
integrity of some types of well casing, notably thermoplastic
casing, to be compromised. Thermoplastics characteristically
lose strength and stiffness as the temperature of the casing
increases. Because collapse pressure resistance of a casing is
proportional to the material stiffness, if casing temperatures are
raised sufficiently this can result in failure of the casing (Johnson
etal, 1980).
Molz and Kurt (1 979) and Johnson et al. (1980) studied the
heat of hydration problem and concluded:
1) peak casing temperatures increase as the grout
thickness increases. Temperature rises for casings
surrounded by 1.5 inches to 4-inches of Type I
neat cement ranged from 16ฐF to 45ฐF;
temperature rises for casings surrounded by 12
inches of grout (i.e. where washouts or caving or
collapse of formation materials into the borehole
might occur) can be in excess of 170 ฐF. In the
former case, plastic pipe retains a large fraction of
collapse strength, but in the latter case, some
types of plastic pipe lose a large fraction of the
collapse strength (Gross, 1970);
2) the ratio of the grout-soil interface surface area to
the volume of grout significantly influences peak
casing temperatures. Additionally, peak
temperature rise for any casing size is nonlinear
with respect to grout thickness. Lower peak
temperatures can thus be expected for smaller-
diameter casings; and
3) peak temperatures are normally reached 8 to 10
hours after water is added to the cement, and
casing temperatures remain near their peak for
several hours before slowly returning to the
original temperature.
The use of setting time accelerators, such as calcium chlo-
ride, gypsum or aluminum powder can increase the heat of
hydration and cause casings to overheat while the grout is
curing. This temperature increase poses an increased potential
for casing failure. Both Molz and Kurt (1979) and Johnson et al.
(1980) attribute uncommon premature collapses of neat cement
grouted thermoplastic-cased wells to two factors: 1) that most
100
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MATRIX NUMBER 39
General Hydrogeologic Conditions & Well Design Requirements
Consolidated; invasion of formation by drilling fluid not permitted; casing diameter 4 inches or less.
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EXPLANATORY NOTES:
we,, does not per.it ซhe Use o, drH,,na ,,,- and a^Uves ,n construction.
3 Boreholes are expected to be sufficiently stable to permit open hole completion,
4. Smud roTary fnd cab.e tool methods are potentiai.y ve, thereby reducing options to ซr dnH.ng methods.
5, Air rotary may require extra air and/or special drill pipe.
205
-------
MATRIX NUMBER 40
General Hydrogeologic Conditions & Well Design Requirements
Consolidated; invasion of formation by drilling fluid not permitted; casing diameter 4 to 8 inches.
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Air Rotary
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Dual Wall Rotary
Cable Tool
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Appendix C
(Supplement to Chapter 8)
Abandonment of Test Holes, Partially Completed Wells and Completed Wells
(American Water Works Association, 1984)
Section 1.1 General
The recommendations contained in this appendix pertain
to wells and test holes in consolidated and unconsolidated
formations. Each sealing job should be considered as an
individual problem, and methods and materials should be
determined only after carefully considering the objectives
outlined in the standard.
Section 1.2 Wells in Unconsolidated Formations
Normally, abandoned wells extending only into consoli-
dated formations near the surface and containing water under
water-table conditions can be adequately sealed by filling with
concrete, grout, neat cement, clay, or clay and sand. In the event
that the water-bearing formation consists of coarse gravel and
producing wells are located nearby, care must be taken to select
sealing materials that will not affect the producing wells.
Concrete may be used if the producing wells can be shut down
for a sufficient time to allow the concrete to set. Clean, disin-
fected sand or gravel may also be used as fill material opposite
the waterbearing formation. The remainder of the well, espe-
cially the upper portion, should be filled with clay, concrete,
grout, or neat cement to exclude surface water. The latter
method, using clay as the upper sealing material, is especially
applicable to large diameter abandoned wells.
In gravel-packed, gravel-envelope, or other wells in which
coarse material has been added around the inner casing to
within 20 to 30 ft (6.1 to 9.1 m) of the surface, sealing outside
the casing is very important. Sometimes this scaling may
require removal of the gravel or perforation of the casing.
Section 1.3 Wells in Creviced Formations
Abandoned wells that penetrate limestone or other creviced
or channelized rock formations lying immediately below the
surface deposits should preferably be filled with concrete,
grout, or neat cement to ensure permanence of the seal. The use
of clay or sand in such wells is not desirable because fine-
-grained fill material may be displaced by the flow of water
through crevices or channels. Alternate layers of coarse stone
and concrete may be used for fill material through the water-
producing horizon if limited vertical movement of water in the
formation will not affect the quality or quantity of water in
producing wells. Only concrete, neat cement, or grout should be
used in this type of well. The portion of the well between a point
10 to 20 ft (3.0 to 6.1 m) below and a point 10 to 20 ft (3.0 to 6.1
m) above should be sealed and a plug of sealing material formed
above the creviced formation. Clay or sand maybe used to fill
the upper part of the well to within 20 ft (6.1 m) of ground level.
The upper 20 ft (6.1 m) should be sealed with concrete or
cement grout.
Section 1.4 Wells in Noncreviced Rock Formations
Abandoned wells encountering non-creviced sandstone or
other water-bearing consolidated formations below the surface
deposits may be satisfactorily sealed by filling the entire depth
with clay, provided there is no movement of water in the well.
Clean sand, disinfected if other producing wells nearby,
may also be used through the sandstone up to a point 10 to 20
ft (3.0 to 6.1 m) below the bottom of the casing. The upper
portion of this type of well should be filled with concrete, neat
cenent, grout or clay to provide an effective seal against
entrance of surface water. If there is an appreciable amount of
upward flow, pressure cementing or mudding may be advis-
able.
Section 1.5 Multiple Aquifer Wells
Some special problems may develop in sealing wells
extending into more than one aquifer. These wells should be
filled and sealed in such a way that exchange of water from one
aquifer to another is prevented. If no appreciable movement of
water is encountered, filling with concrete, neat cement, grout,
or alternate layers of these materials and sand will prove
satisfactory. When velocities are high, the procedures outlined
in. Sec. 1.6 are recommended. If alternate concrete plugs or
bridges are used, they should be placed in known nonproducing
horizons or, if locations of the nonproducing horizons are not
known, at frequent intervals. Sometimes when the casing is not
grouted or the formation is noncaving, it may be necessary to
break, slit, or perforate the casing to fill any annular space on the
outside.
Section 1.6 Wells with Artesian Flow
The sealing of abandoned wells that have a movement
between aquifers or to the surface requires special attention.
Frequently the movements of water maybe sufficient to make
sealing by gravity placement of concrete, cement grout, neat
cement, clay or sand impractical. In, such wells, large stone
aggregate (not more than one third of the diameter of the hole),
lead wool, steel shavings, a well packer, or a wood or cast-lead
plug or bridge will be needed to restrict the flow and thereby
permit the gravity placement of sealing material above the
formation producing the flow. If preshaped or precast plugs are
used, they should be several times longer than the diameter of
the well, to prevent tilting.
Since it is very important in wells of this type to prevent
circulation between formations, or loss of water to the surfaces
or to the annular space outside the casing, it is recommended
that pressure cementing, using the minimum quantity of water
that will permit handling, be used. The use of pressure mudding
instead of this process is sometimes permissible.
207
-------
In wells in which the hydrostatic head producing flow to
the surface is low, the movement of water maybe arrested by
extending the well casing to an elevation above the artesian-
pressure surface. Previously described sealing methods suit-
able to the geologic conditions can then be used.
Section 1.7 Sealing Materials
A number of materials that can be used for sealing wells
satisfactorily, including concrete, cement grout, neat cement,
clay, sand, or combinations of these materials, are mentioned
in this appendix. Each material has certain characteristics and
distinctive properties; therefore, one material may be especially
suited for doing a particular job. The selection of the material
must be based on the construction of the well, the nature of the
formations penetrated, the material and equipment available,
the location of the well with respect to possible sources of
contamination, and the cost of doing the work.
Concrete is generally used for filling the upper part of the
well or water-bearing formations, for plugging short sections of
casings, or for filling large-diameter wells. Its use is cheaper
than neat cement or grout, and it makes a stronger plug or seal.
However, concrete will not penetrate seams, crevices, or in-
terstices. Furthermore, if not properly placed, the aggregate is
likely to separate from the cement.
Cement grout or neat cement and water are far superior for
sealing small openings, for penetrating any annular space
outside of casings, and for falling voids in the surrounding
formation. When applied under pressure, they are strongly
favored for sealing wells under artesian pressure or those
encountering more than one aquifer. Neat cement is generally
preferred to grout because it does not separate.
Clay, as a heavy mud-laden or special clay fluid applied
under pressure, has most of the advantages of cement grout. Its
use is preferred by some competent authorities particularly for
sealing artesian wells. Others feel that it may, under some
conditions, eventually be carried away into the surrounding
formations.
Clay in a relatively dry state, clay and sand, or sand alone
may be used advantageously as sealing materials, particularly
under water-table conditions where diameters are large, depths
are great, formations are caving, and there is no need for
achieving penetration of openings in casings, liners, or for-
mations, or for obtaining a watertight seal at any given spot.
Frequently combinations of these materials are necessary.
The more expensive materials are used when strength, penetra-
tion, or watertightness are needed. The less expensive materials
are used for the remainder of the well. Cement grout or neat
cement is now being mixed with bentonite clays and various
aggregates. Superior results and lower cost are claimed for such
mixtures.
Reference
American Water Works Association, 1984. Appendix I:
Abandonment of test holes, partially completed wells and
completed wells; American Water Works Association
Standard for Water Wells, American Water Works
Association, Denver, Colorado, pp. 45-47.
208
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Glossary
Abandonment
The complete sealing of a well or borehole with grout or
other impermeable materials to restore the original
hydrogeologic conditions and/or to prevent contamination of
the aquifer.
Absorption
The penetration or apparent disappearance of molecules or
ions of one or more substances into the interior of a solid or
liquid. For example, in hydrated bentonite, the planar water that
is held between the mica-like layers is the result of absorption
(Ingersoll-Rand, 1985).
Accelerator
Substances used to hasten the setting or curing of cement
such as calcium chloride, gypsum and aluminum powder.
Acrylonitrile Butadiene Styrene (ABS)
A thermoplastic material produced by varying ratios of
three different monomers to produce well casing with good heat
resistance and impact strength.
Adapter
A device used to connect two different sizes or types of
threads, also known as sub, connector or coupling (Ingersoll-
Rand, 1985).
Adsorption
The process by which atoms, ions or molecules are held to
the surface of a material through ion-exchange processes.
Advection
The process by which solutes are transported with and at
the same rate as moving ground water.
Air Rotary Drilling
A drilling technique whereby compressed air is circulated
down the drill rods and up the open hole. The air simultaneously
cools the bit and removes the cuttings from the borehole.
Air Rotary with Casing Driver
A drilling technique that uses conventional air rotary
drilling while simultaneously driving casing. The casing driver
is installed in the mast of a top-head drive air rotary drilling rig.
Aliphatic Hydrocarbons
A class of organic compounds characterized by straight or
branched chain arrangement of the constituent carbon atoms
joined by single covalent bonds with all other bonds to hydro-
gen atoms.
Alkalinity
The ability of the salts contained in the ground water to
neutralize acids. Materials that exhibit a pH of 7 or greater are
alkaline. High-pH materials used in well construction may have
the potential to alter ambient water quality.
Aluminum Powder
An additive to cement that produces a stronger, quick-
setting cement that expands upon curing.
Anisotropic
Having some physical property that varies with direction
(Driscoll, 1986).
Annular Sealant
Material used to provide a positive seal between the bore-
hole and the casing of the well. Annular sealants should be
impermeable and resistant to chemical or physical deteriora-
tion.
Annular Space or Annulus
The space between the borehole wall and the well casing,
or the space between a casing pipe and a liner pipe.
Aquifer
A geologic formation, group of formations, or part of a
formation that can yield water to a well or spring.
Aquifer Test
A test involving the withdrawal of measured quantities of
water from or addition of water to a well and the measurement
of resulting changes in head in the aquifer both during and after
the period of discharge or addition (Driscoll, 1986).
Aquitard
A geologic formation, or group of formations, or part of a
formation of low permeability that is typically 'saturated but
yields very limited quantities of water to wells.
Aromatic Hydrocarbons
A class of unsaturated cyclic organic compounds contain-
ing one or more ring structures or cyclic groups with very stable
bonds through the substitution of a hydrogen atom for an
element or compound.
Artesian Well
A well deriving water from a confined aquifer in which the
water level stands above the ground surface; synonymous with
flowing artesian well (Driscoll, 1986).
209
-------
Artificial Filter Pack
See Grovel Pack.
Attenuation
The reduction or removal of constituents in the ground
water by the sum of all physical, chemical and biological events
acting upon the ground water.
Auger Flights
Winding metal strips welded to the auger sections that
carry cuttings to the surface during drilling.
Backwash (Well Development)
The surging effect or reversal of water flow in a well that
removes fine-grained material from the formation surrounding
the borehole and helps prevent bridging (Driscoll, 1986).
Backwashing
A method of filter pack emplacement whereby the filter
pack material is allowed to fall freely through the annulus while
clean fresh water is simultaneously pumped down the casing.
Bailer
A long, narrow bucket-like device with an open top and a
check valve at the bottom that is used to remove water and/or
cuttings from the borehole.
Bailing (Well Development)
A technique whereby a bailer is raised and lowered in the
borehole to create a strong outward and inward movement of
water from the borehole to prevent bridging and to remove fine
materials.
Barium Sulfate
A natural additive used to increase the density of drilling
fluids.
Bentonite
A hydrous aluminum silicate available in powder,
granular or pellet form and used to provide a tight seal between
the well casing and borehole. Bentonite is also added to drilling
fluid to impart specific characteristics to the fluid.
Biodegradation
The breakdown of chemical constituents through the bio-
logical processes of naturally occuring organisms.
Bit
The cutting tool attached to the bottom of the drill stem. Bit
design varies for drilling in various types of formations and
includes roller, cone and drag-type bits.
Bit, Auger
Used for soft formations with auger drill (Ingersoll-Rand,
1985).
Borehole
A hole drilled or bored into the earth, usually for explor-
atory or economic purposes, such as a water well or oil well
(united States Environmental Protection Agency, 1986).
Borehole Geophysics
Techniques that use a sensing device that is lowered into a
borehole for the purpose of characterizing geologic formations
and their associated fluids. The results can be interpreted to
determine lithology, geometry Resistivity, bulk density,pcmsity,
permeability, and moisture content and to define the source,
movement, and physical/chemical characteristics of ground
water (United States Environmental Protection Agency, 1986).
Bridge Seal
An artificial plug set to seal off specific zones in the
abandonment of a well.
Bridge-Slot Intake
A well intake that is manufactured on a press from flat
sheets that are perforated, rolled and seam welded where the
slots are vertical and occur as parallel openings longitudinally
aligned to the well axis.
Bridging
The development of gaps or obstructions in either grout or
filter pack materials during emplacement. Bridging of particles
in a naturally developed or artificial gravel pack can also occur
during development.
Cable Tool Drilling
A drilling technique whereby a drill bit attached to the
bottom of a weighted drill stem is raised and dropped to crush
and grind formation materials.
Calcium Chloride
A soluble calcium salt added to cement slurries to acceler-
ate the setting time, create higher early strength and to minimize
movement of the cement into zones of coarse material.
Calcium Hydroxide
A primary constituent of wet cement.
Caliper Logging
A logging technique used to determine the diameter of a
borehole or the internal diameter of casing through the use of a
probe with one to four spring expanding prongs. Caliper log-
ging indicates variations in the diameter of the vertical profile.
Capillary Fringe
The pores in this zone are saturated but the pressure heads
are less than atmospheric.
Casing
An impervious durable pipe placed in a well to prevent the
borehole walls from caving and to seal off surface drainage or
undesirable water, gas, or other fluids and prevent their en-
trance into the well. Surface or temporary casing means a
temporary casing placed in soft, sandy or caving surface forma-
tion to prevent the borehole from caving during drilling. Pro-
tective casing means a short casing installed around the well
casing. Liner pipe means a well casing installed without driving
within the casing or open borehole.
210
-------
Casing, Flush-Coupled
Flush-coupled casing is joined with a coupling with the
same outside diameter as the casing, but with two female
threads. The inside diameterof the coupling is approximately 3/
16 inch smaller than that of the casing. Flush-coupled casing
has thinner walls than flush-joint casing (Ingersoll-Rand, 1985).
Casing, Flush-Joint
Flush-joint casing has a male thread at one end and a female
thread at the other. No coupling is used (Ingersoll-Rand, 1985).
Casing Driver
A device fitted to the top-head drive of a rotary rig that is
used to advance casing into the subsurface.
Cation Exchange Capacity (CEC)
The measure of the availability of cations that can be
displaced from sites on surfaces or layers and which can be
exchanged for other cations. For geologic materials, CEC is
expressed as the number of milliequivalents of cations that can
be exchanged in a sample with a dry mass of 100 grams.
Cement
A mixture of calcium aluminates and silicates made by
combining lime and clay while heating and which is emplaced
in the annular space to form a seal between the casing and the
borehole.
Cement Bond Log
A logging device that uses acoustical signals to determine
the integrity of the cement bond to the casing.
Cement, Quick-Setting
Cement of special composition and freeness of grind that
sets much quicker than ordinary cement. This cement is used for
deviating holes and plugging cavities (Ingersoll-Rand, 1985).
Cementing
The emplacement of a cement slurry by various methods so
that it fills the space between the casing and the borehole wall
to a prdetermined height above the bottom of the well. This
secures the casing in place and excludes water and other fluids
from the borehole.
Center Plug
A plug within the pilot assembly of a hollow-stem auger
that is used to prevent formation materials from entering the
stem of the lead auger during drilling.
Center Rod
A rod attached to the pilot assembly that facilitates removal
from the lead end of the hollow-stem auger.
Centralizer
Spring-loaded guides that are used to center the casing in
the borehole to ensure effective placement of filter pack or
grout.
Check Valve
Ball and spring valves on core barrels, rods and bailers that
are used to control water flow in one direction only.
Circulate
To cycle drilling fluid through the drill pipe and borehole
while drilling operations are temporarily suspended to condi-
tion the drilling fluid and the borehole before hoisting the drill
pipe and to obtain cuttings from the bottom of the well before
drilling proceeds (Ingersoll-Rand, 1985).
Circulation
The movement of drilling fluid from the suction pit through
the pump, drill pipe, bit and annular space in the borehole and
back again to the suction pit. The time involved is usually
referred to as circulation time (Ingersoll-Rand, 1985).
Circulation, Loss of
The loss of drilling fluid into the formation through crev-
ices or by infiltration into a porous media.
Clay
A plastic, soft, variously colored earth, commonly a hy-
drous silicate of alumina, formed by the decomposition of
feldspar and other aluminum silicates (Ingersoll-Rand, 1985).
Collapse Strength
The capability of a casing or well intake to resist collapse
by any or all external loads to which it is subjected during and
after installation.
Compressive Strength
The greatest compressive stress that a substance can bear
without deformation.
Conductivity
A measure of the quantity of electricity transferred across
unit area per unit potential gradient per unit time. It is the
reciprocal of Resistivity.
Cone of Depression
A depression in the ground-water table or potentiometric
surface that has the shape of an inverted cone and develops
around a well from which water is being withdrawn. It defines
the area of influence of a well (Driscoll 1986).
Cone of Impression
A conical mound on the water table that develops in
response to well injection whose shape is identical to the cone
of depression formed during pumping of the aquifer.
Confined Aquifer
An aquifer which is bounded above and below by low-
permeability formations.
Confined Bed
The relatively impermeable formation immediately over-
lying or underlying a confined aquifer.
Contaminant
Any physical, chemical, biological or radiological sub-
stance or matter in water that has an adverse impact.
Contamination
Contamination is the introduction into ground water of any
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chemical material, organic material, live organism or radioac-
tive material that will adversely affect the quality of the ground
water.
Continuous Sampling Tube System
Thin-wall sampling tube attached in advance of the cutting
head of the hollow-stem auger that allows undisturbed samples
to be taken continuously while the augers are rotated.
Continuous Slot Wire-Wound Intake
A well intake that is made by winding and welding trian-
gular-shaped, cold-rolled wire around a cylindrical array of
rods. The spacing of each successive turn of wire determines the
slot size of the intake.
Core
A continuous columnar sample of the lithologic units
extracted from a borehole. Such a sample preserves strati-
graphic contacts and structural features (United States Envi-
ronmental Protection Agency, 1986).
Core Barrel
A reaming shell and length of tubing used during air or mud
rotary drilling to collect formation samples in both consolidated
and unconsolidated formations. Core barrels may be single or
double walled and of a swivel or rigid type.
Core Lifter
A tapered split ring inside the bit and surrounding the core.
On lifting the rods, the taper causes the ring to contract in
diameter, seizing and holding the core (Ingersoll-Rand, 1985).
Corrosion
The adverse chemical alteration that reverts elemental
metals back to more stable mineral compounds and that affects
the physical and chemical properties of the metal.
Cost-Pius Contract
Drilling contracts that list specific costs associated with
performing the work and include a percentage of those costs as
an additional amount that will be paid to perform a job.
Coupling
A connector for drill rods, pipe or casing with identical
threads, male and/or female, at each end (Ingersoll-Rand,
1985).
Cross Contamination
The movement of contaminants between aquifers or water-
bearing zones through an unsealed or improperly sealed bore-
hole.
Cutter Head
The auger head located at the lead edge of the auger column
that breaks up formation materials during drilling.
Cuttings
Formation particles obtained from a borehole during the
drilling process.
Decontamination
A variety of processes used to clean equipment that has
contacted formation material or ground water that is known to
be or suspected of being contaminated.
Dennison Sampler
A specialized sampler of a double-tube core design with a
thin inner tube that permits penetration in extremely stiff or
highly cemented unconsolidated deposits while collecting a
thin-wall sample.
Density
The weight of a substance per unit volume.
Development
The act of repairing damage to the formation caused during
drilling procedures and increasing the porosity and permeabil-
ity of the materials surrounding the intake portion of the well
(Driscoll, 1986).
Diatomaceous Earth
A cement additive composed of siliceous skeletons of
diatoms used to reduce slurry density, increase water demand
and thickening time while reducing set strength.
Differential Pressure
The difference in pressure between the hydrostatic head of
the drilling fluid-filled or empty borehole and the formation
pressure at any given depth (Ingersoll-Rand, 1985).
Direct Mud Rotary
A drilling technique whereby a drilling fluid is pumped
down the drill rod, through the bit and circulates back to the
surface by moving up the annular space between the drill rods
and the borehole.
Dispersion
A process of contaminant transport that occurs by me-
chanical mixing and molecular diffusion.
Dissociation
The splitting up of a compound or element into two or more
simple molecules, atoms or ions. Applied usually to the effect
of the action of heat or solvents upon dissolved substances. The
reaction is reversible and not as permanent as decomposition;
that is, when the solvent is removed, the ions recombine
(Ingersoll-Rand, 1985).
DNAPLS
Acronym for dense, nonaqueous-phase liquids.
Down gradient
In the direction of decreasing hydrostatic head (United
States Environmental Protection Agency, 1986).
Downgradient Well
A well that has been installed hydraulically downgradient
of the site and is capable of detecting the migration of contami-
nants from a regulated unit. Regulations require the installation
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contaminant migration (United States Environmental Protec-
tion Agency, 1986).
Down-the-Hole Hammer
A pneumatic drill operated at the bottom of the drill pipe by
air pressure provided from the surface.
Drawdown
The extent of lowering of the water surface in a well and
water-bearing zone resulting from the discharge of water from
the well.
Drill Collar
A length of heavy, thick-walled pipe used to stabilize the
lower drill string, to minimize bending caused by the weight of
the drill pipe and to add weight to the bit.
Drill Pipe
Special pipe used to transmit rotation from the rotating
mechanism to the bit. The pipe also transmits weight to the bit
and conveys air or fluid which removes cuttings from the
borehole and cools the bit (Driscoll, 1986).
Drill Rod
Hollow flush-join ted or coupled rods that are rotated in the
borehole that are connected at the bottom to the drill bit and on
the top 10 the rotating or driving mechanism of a drilling rig.
Drill String
The string of pipe that extends from the bit to the driving
mechanism that serves to carry the mud down the borehole and
to rotate the bit.
Drilling Fluid
A water or air-based fluid used in the well drilling opera-
tion to remove cuttings from the borehole, to clean and cool the
bit, to reduce friction between the drill string and the sides of the
borehole and to seal the borehole (Driscoll, 1986),
Drive Block
A heavy weight used to drive pipe or casing through
unconsolidated material.
Drive Couplings
Heavy-duty couplings used to join sections of heavy-wall
casing that are specifically designed to withstand the forces
during driving casing.
Drive Head
A component fastened to the top of pipe or casing to lake
the blow of the drive block (Ingersoll-Rand, 1985).
Drive Shoe *
A forged steel collar with a cutting edge fastened onto the
bottom of the casing to shear off irregularities in the hole as the
casing advances. It is designed to withstand drive pressures to
protect the lower edge of the casing as it is driven (United S lates
Environmental Protection Agency, 1986).
Driven Well
A well that is driven to the desired depth, either by hand or
machine; may employ a wellpoint, or alternative equipment.
Drop Hammer
A weighted device used to drive samplers during drilling
and sampling.
Dual-Wall Reverse Circulation
A dri Jling technique whereby the circulating fluid is pumped
down between the outer casing and the inner drill pipe, through
the drill bit and up the inside of the drill pipe,
Effective Grain Size (Effective Diameter)
The particle grain size of a sample where 90 percent
represents coarser-size grains and 10 percent represents firter-
sii-e grains, i.e., the coarsest diameter in the finest 10 percent of
the sediment.
Electric Logging
Logging techniques used in fluid-filled boreholes to obtain
information concerning the porosity, permeability and fluid
content of the formations drilled based on thedielectic properties
of the aquifer materials.
Established Grade
The permanent point of contact of me ground or artificial
surface with the casing or curbing of the well.
Established Ground Surface
The permanent elevation of the surface at the site of the
well upon completion.
Filter Cake (Mudcake)
The suspended solids that are deposited on the borehole
wall during the process of drilling.
Filter Cake Thickness (Mudcake)
A measurement, in 32nd of an inch, of the solids deposited
on filter paper during the standard 30-minute API filter test, or
measurement of the solids deposited on filter paper for a 71/2-
minute duration (Ingersoll-Rand, 1985).
Filter Pack
Sand, gravel or glass beads that are uniform, clean and
well-rounded that are placed in the annulus of the well between
the borehole wall and the well intake to prevent formation
material from entering through the well intake and to stabilize
the adjacent formation.
Filter Pack Ratio
A ratio used to express size differential between the forma-
tion materials and the filler pack that typically refers to either
the average grain size (DJO) or the 70-percent (DTO) retained size
of the formation material.
Filtrate Invasion
The movement of drilling fluid into the adjacent formation
that occurs when the weight of the drilling fluid substantially
exceeds the natural hydrostatic pressure of the formation.
Fixed-Price Contracts
Drilling contracts that list the manpower, materials and
additional costs needed to perform the work specified as a fixed
cost payable upon completion.
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Floaters
Light-phase organic liquids in ground water capable of
forming an immiscible layer that can float on the water table
(United States Environmental Protection Agency, 1986).
Float Shoe
A drillable valve attached to the bottom of the casing.
Flocculation
The agglomeration of finely divided suspended solids into
larger, usually gelatinous particles through electrical charge
alignment of particles.
Flow Meter
A tool used to monitor fluid flow rates in cased or uncased
boreholes using low-inertia impellers or through changes in
thermal conductance as liquids pass through the tool.
Flow-Through Well
The installation of a small-diameter well intake that pen-
etrates all or a significant portion of the aquifer. The well is
designed to minimize distortion of the flow field in the aquifer.
Fluid Loss
Measure of the relative amount of fluid lost (filtrate)
through permeable formations or membranes when the drilling
fluid is subjected to a pressure differential (Ingersoll-Rand,
1985).
Fluoropolymers
Man-made materials consisting of different formulations
of monomers molded by powder metallurgy techniques that
exhibit anti-stick properties and resistance to chemical and
biological attack.
Flush-Coupled Casing
See Casing, Flush-coupled.
Flush-Joint Casing
See Casing, Flush-joint.
F]y Ash
An additive to cement that increases sulfate resistance and
early compressive strength.
Formation
A mappable unit of consolidated material or unconsoli-
dated material characterized by a degree of lithologic homo-
geneity.
Formation Damage
Damage to the formation resulting from drilling activities
(e.g., the invasion of drilling fluids or formation of mudcake)
that alter the hydraulic properties of formation materials.
Formation Fluid
The natural fluids present in the formation or aquifer.
Formation Stabilizer (Filter Pack)
A sand or gravel placed in the annulus of the well between
the borehole and the well intake to provide temporary or long-
term support for the borehole (Driscoll, 1986).
Gel Strength
A measure of the capability of the drilling fluid to maintain
suspension of particulate matter in the mud column when the
pump is off.
Grain Size
The general dimensions of the particles in a sediment or
rock, or of the grains of a particular mineral that make up a
sediment or rock. It is common for these dimensions to be
referred to with broad terms, such as fine, medium, and coarse.
A widely used grain size classification is the Udden-Wentworth
grade scale (United States Environmental Protection Agency, 1986.
Gravel Pack (Artificial Filter Pack); see also Filter
Pack
A term used to describe gravel or other permeable filter
material placed in the annular space around a well intake to
prevent the movement of finer material into the well casing, to
stabilize the formation and to increase the ability of the well to
yield water.
Ground Water
Any water below the surface of the earth, usually referring
to the zone of saturation.
Grout
A fluid mixture of neat cement and water with various
additives or bentonite of a consistency that can be forced
through a pipe and emplaced in the annular space between the
borehole and the casing to form an impermeable seal.
Grouting
The operation by which grout is placed between the casing
and the wall of the borehole to secure the casing in place and to
exclude water and other fluids from moving into and through
the borehole.
Gypsum
An additive to cement slurries that produces a quick-
setting, hard cement that expands upon curing.
Halogenated Hydrocarbons
An organic compound containing one or more halogens
(e.g., fluorine, chlorine, bromine, and iodine) (United States
Environmental Protection Agency, 1986).
Hand Auger
Any of a variety of hand-operated devices for drilling
shallow holes into the ground.
Head LOSS
That part of potential energy that is lost because of friction
as water flows through a porous medium.
Heat of Hydration
Exothermic or heat-producing reaction that occurs during
the curing of cement.
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Perched Ground Water
Ground water in a saturated zone that is separated from the
main body of ground water by a less permeable unsaturated
zone or formation.
Percolate
The act of water seeping or filtering through materials
without a definite channel,
Permeability
A measure of the relative ease with which a porous medium
can transmit a liquid under a potential gradient (United States
Environmental Protection Agency, 1975).
Piezometers
Generally a small-diameter, non-pumping well used to
measure the elevation of the water table or potentiometric
surface (United States Environmental Protection Agency,
1986).
Pilot Assembly
The assembly placed at the lead end of the auger consisting
of a solid center plug and a pilot bit.
Plugs, Casing
Plug made of drillable material to correspond to the inside
diameter of the casing. Plugs are pumped to bottom of casing to
force all cement outside of casing (Ingersoll-Rand, 1985).
Plugging
The complete filling of a borehole or well with an imper-
meable material which prevents flow into and through the
borehole or well.
Plume
An elongated and mobile column or band of a contaminant
moving through the subsurface.
Polumeric Additives
The natural organic colloids developed from the guar plant
that are used for viscosity control during drilling.
Polyvinyl Chloride (PVC)
Thermoplastics produced by combining PVC resin with
various types of stabilizers, lubricants, pigments, fillers and
processing aids, often formulated to produce rigid well casing.
Porosity
The percentage of void spaces or openings in a consoli-
dated or unconsolidated material.
Portland Cement
Cement specified as Type I or Type 11 under ASTM C-150
standards.
Potentiometric Data
Ground-water surface elevations obtained at wells and
piezometers that penetrate a water-bearing formation.
Potentiometric Surface
An imaginary surface representing the total head of ground
water in a confined aquifer that is defined by the level to which
water will rise in a well (Driscoll, 1986).
Precipitate
Material that will separate out of solution or slurry as a
solid under changing chemical and or physical conditions.
Pressure Sealing
A process by which a grout is confined within the borehole
or casing by the use of retaining plugs or packers and by which
sufficient pressure is applied to drive the grout slurry into and
within the annular space or zone to be grouted.
Protective Casing
A string of casing set in the borehole to stabilize a section
of the formation and/or to prevent leakage into and out of the
formation and to allow drilling to continue to a greater depth.
Protectors, Thread
A steel box and pin used to plug each end of a drill pipe
when it is pulled from the borehole to prevent foreign matter or
abrasives from collecting on the greasy threads and to protect
threads from corrosion or damage while transporting or in
storage (Ingersoll-Rand, 1985).
Puddled Clay
Puddling clay is a mixture of bentonite, other expansive
clays, tine-grained material and water, in a ratio of not less than
7 pounds of bentonite or expansive clay per gallon of water. It
must be composed of not less than 50 percent expansive clay
with the maximium size of the remaining portion not exceeding
that of coarse sand.
Pulling Casing
To remove the casing from a well.
Pumping/Overpumpinf/Backwashing
A well development technique that alternately starts and
stops a pump to raise and drop the column of water in the
borehole in a surging action.
Pump Test
A test used to determine aquifer characteristics performed
by pumping a well for a period of time and observing the change
in hydraulic head that occurs in adjacent wells. A pump test may
be used to determine degree of hydraulic interconnection between
different water-bearing units, as well as the recharge rate of a
well (United States Environmental Protection Agency, 1986).
Pumping Water Level
The elevation of the surface of the water in a well or the
water pressure at the top of a flowing artesian well after a period
of pumping or flow at a specified rate.
Radioactive Logging
A logging process whereby a radioactive source is lowered
down a borehole to determine formation characteristics. Ra-
dioactive logging devices typically used for ground-water
investigations include gamma and neutron logging probes.
Radius of Influence (Cone of Depression)
The radial distance from the center of a well under pumping
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Heaving Sand
Saturated sands encountered during drilling where the
hydrostatic pressure of the formation is greater than the bore-
hole pressure causing the sands to move up into the borehole.
High-Yield Drilling Clay
A classification given to a group of commercial drilling
clay preparations having a yield of 35 to 50 bbl/ton and
intermediate between bentonite and low-yield clays. High-
yield drilling clays are usually prepared by peptizing low-yield
calcium montmorillonite clays or, in a few cases, by blending
some bentonite with the peptized low-yield clay (Ingersoll-
Rand, 1985).
Hollow-Stem Auger Drilling
A drilling technique in which hollow, interconnected flight
augers, with a cutting head, are pressed downward as the auger
is rotated.
Homogeneous
Exhibiting a uniform or similar nature.
Hydraulic Conductivity
A coefficient of proportionality that describes the rate at
which a fluid can move through a permeable medium. It is a
function of both the media and of the fluid flowing through it
(United States Environmental Protection Agency, 1986).
Hydraulic Gradient
The change in static head per unit of distance in a given
direction. If not specified, the direction generally is understood
to be that of the maximum rate of decrease in head.
Hydrostatic Head
The pressure exerted by a column of fluid, usually ex-
pressed in pounds per square inch (psi). To determine the
hydrostatic head at a given depth in psi, multiply the depth in
feet by the density in pounds per gallon by 0.052 (Ingersoll-
Rand, 1985).
Immiscible
Constituents that are not significantly soluble in water.
Incrustation (Encrustation)
The process by which a crust or coating is formed on the
well intake and/or casing, typically through chemical or bio-
logical reactions.
Induction Tool
A geophysical logging tool used to measure pore fluid
conductivity.
Inhibitor (Mud)
Substances generally regarded as drilling mud contami-
nants, such as salt and calcium sulfate, are called inhibitors
when purposely added to mud so that the filtrate from the
drilling fluid will prevent or retard the hydration of formation
clays and shales (Ingersoll-Rand, 1985).
Isotropic
A medium whose properties are the same in all directions.
Jet Percussion
A drilling process that uses a wedge-shaped drill bit that
discharges water under pressure while being raised and lowered
to loosen or break up material in the borehole.
Kelly
Hollow steel bar that is in the main section of drill string to
which power is directly transmitted from the rotary table to
rotate the drill pipe and bit (Driscoll, 1986).
Ketones
Class of organic compounds where the carbonyl group is
bonded to two alkyl groups (United States Environmental
Protection Agency, 1986).
Knock-Out Plate
A nonretrievable plate wedged within the auger head that
replaces the traditional pilot assembly and center rod that is
used to prevent formation materials from entering the hollow
auger stem.
Logging, Radioactive
The logging process whereby a neutron source is lowered
down the borehole, followed by a recorder, to determine mois-
ture content and to identify water-bearing zones.
Lost Circulation
The result of drilling fluid escaping from the borehole into
the formation by way of crevices or porous media (Driscoll,
1986).
Louvered Intake
A well intake with openings that are manufactured in solid-
wall metal tubing by stamping outward with a punch against
dies that control the size of the openings.
Low-Solids Muds
A designation given to any type of mud where high-
performing additives have been partially or wholly substituted
for commercial or natural clays (Ingersoll-Rand, 1985).
Low-Yield Well
A relative term referring to a well that cannot recover in
sufficient time after well evacuation to permit the immediate
collection of water samples (United States Environmental
Protection Agency, 1986).
Machine-Slotted Intake
Well intakes fabricated from standard casing where slots of
a predetermined width are cut into the casing at regular intervals
using machining tools.
Male and Female Threads
Now called pin and box threads, as in the oil industry
(Ingersoll-Rand, 1985).
Marsh Funnel
A device used to measure drilling fluid viscosity where the
time required for a known volume of drilling fluid to drain
through an orifice is measured and calibrated against a time for
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conditions to the point where there is no lowering of the water
table or potentiometric surface (Driscoll, 1986).
Reamer
A bit-like tool, generally run directly above the bit, used to
enlarge and maintain a straight borehole (After Ingersoll-Rand,
1985).
Reaming
A drilling operation used to enlarge a borehole.
Rehabilitation
The restoration of a well to its most efficient condition
using a variety of chemical and mechanical techniques that are
often combined for optimum effectiveness.
Resistivity
The electrical resistance offered to the passage of a current,
expressed in ohm-meters; the reciprocal of conductivity. Fresh-
water muds are usually characterized by high Resistivity; salt-
water muds, by low Resistivity (Ingersoll-Rand, 1985).
Reverse Circulation
A method of filter pack emplacement where the filter pack
material is fed into the annulus around the well intake concur-
rently with a return flow of water. The water is pumped to the
surface through the casing.
In dual-wall reverse circulation rotary drilling, the circul-
ating fluid is pumped down between the outer casing and inner
drill pipe, and then up and out through the drill bit to the
surface.
Rig
The machinery used in the construction or repair of wells
and boreholes.
Rotary Table Drive
Hydraulic or mechanical drive on a rotary rig used to rotate
the drill stem and bit.
RVCM
Residual vinyl chloride monomer.
Samples
Materials obtained from the borehole during the drilling
and/or formation sampling process that provide geological
information. May also refer to water from completed well used
for hydrogeochemical analysis.
Saturated Zone (Phreatic Zone)
The subsurface zone in which all pore spaces are filled with
water.
Scheduling
Standardization of casing diameters and wall thicknesses
where wall thickness increases as the scheduling number in-
creases.
Screen
See Well Intake.
Seal
The impermeable material, such as cement grout, bento-
nite or pudded clay, placed in the annular space between the
borehole wall and the permanent casing to prevent the downhole
movement of surface water or the vertical mixing of water-
bearing zones.
Segregation
The differential settling of filter pack or other materials that
occurs in the annular space surrounding the intake during
placement by gravity (free fall).
Set Casing
To install steel pipe or casing in a borehole.
Shale Shaker
Vibratory screen connected in line to the circulation sys-
tem of a mud rotary rig through which the drilling fluid passes
and where suspended material is separated and samples are
collected.
Shelby Tube
Device used in conjunction with a drilling rig to obtain an
undisturbed core sample of unconsolidated strata (United States
Environmental Protection Agency, 1986).
Sieve Analysis
Determination of the particle-size distribution of soil,
sediment or rock by measuring the percentage of the particles
that will pass through standard sieves of various sizes (Driscoll,
1986).
Single-Riser/Limited-Interval Well
An individual monitoring well installed with a limited-
length well intake that is used to monitor a specific zone of a
formation.
Sinkers
Dense-phase organic liquids that coalesce in an immiscible
layer at the bottom of the saturated zone (United States Envi-
ronmental Protection Agency, 1986).
Slip-Fit Box and Pin Connections
A type of coupling used to join two hollow-stem auger
sections.
Slotted Couplings
A device attached to the knock-out plate at the base of the
lead auger that allows water to pass into the center of the auger
during drilling while preventing the entrance of sediment or
sand into the hollow stem.
Slotted Well Casing
Well intakes that are fabricated by cutting slots of prede-
termined width at regular intervals by machining tools.
Slug Test
A single well test to determine the in-situ hydraulic con-
ductivity of typically low-permeability formations by the in-
stantaneous addition or removal of a known quantity (slug) of
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water into or from a well, and the subsequent measurement of
the resulting well recovery (United States Environmental
Protection Agency, 1986).
Slurry
A thin mixture of liquid, especially water, and any of
several finely divided substances such as cement or clay par-
ticles (Driscoll, 1986).
Smectite
A commonly used name for clay minerals that exhibit high
swelling properties and a high cation exchange capacity.
Sodium Bentonite
A type of clay added to drilling fluids to increase viscosity.
Solids Concentration or Content
The total amount of solids in a drilling fluid as determined
by distillation that includes both the dissolved and the suspended
or undissolved solids. The suspended solids content maybe a
combination of high and low specific gravity solids and native
or commercial solids. Examples of dissolved solids are the
soluble salts of sodium, calcium and magnesium. Suspended
solids make up the mudcake dissolved solids remain in the
filtrate. The total suspended and dissolved solids contents are
commonly expressed as percent by weight (Ingersoll-Rand,
1985).
Solid-Flight Auger
A solid-stem auger with a cutting head and continuous
flighting that is rotated by a rotary drive head at the surface and
forced downward by a hydraulic pulldown or feed device.
Solvation
The degradation of plastic well casing in the presence of
very high concentrations of specific organic solvents.
Solvent Cementing
A method of joining two sections of casing where solvent
is applied to penetrate and soften the casing pieces and fuses the
casing together as the solvent cement cures.
Sorption
The combined effect of adsorption and/or absorption.
Specific Capacity
The rate of discharge of water from a well per unit of
drawdown of the water level, commonly expressed in gpm/ft or
mVday/m, and that varies with the duration of discharge
(Driscoll, 1986).
Specific Yield
The ratio of the volume of water that a given mass of
saturated rock or soil will yield by gravity to the volume of the
mass expressed as a percentage (Driscoll, 1986).
Split-Spoon Sampler
A hollow, tubular sampling device driven by a 140-pound
weight below the drill stem to retrieve sample of the formation,
Spudding Beam
See Walking Beam.
Standard Dimension Ratio
A ratio expressed as the outside diameter of casing divided
by the wall thickness.
Static Water Level
The distance measured from the established ground sur-
face to the water surface in a well neither being pumped nor
under the influence of pumping nor flowing under artesian
pressure.
Surface Seal
The seal at the surface of the ground that prevents the
intrusion of surficial contaminants into the well or borehole.
Surfactant
A substance capable of reducing the surface tension of a
liquid in which it is dissolved. Used in air-based drilling fluids
to produce foam, and during well development to disaggregate
clays (Driscoll, 1986).
Surge Block
A plunger-like tool consisting of leather or rubber discs
sandwiched between steel or wooden discs that maybe solid or
valved that is used in well development.
Surging
A well development technique where the surge block is
alternately lifted and dropped within the borehole above or
adjacent to the screen to create a strong inward and outward
movement of water through the well intake.
Swivel, Water
A hose coupling that forms a connection between the slush
pumps and the drill string and permits rotation of the drill string
(Ingersoll-Rand, 1985).
Teflon
Trade name for fluoropolymer material.
Telescoping
A method of fitting or placing one casing inside another or
of introducing screen through a casing diameter larger than the
diameter of the screen (United States Environment Protection
Agency, 1975).
Temperature Survey
An operation to determine temperatures at various depths
in the wellbore, typically used to ensure the proper cementing
of the casing or to find the location of inflow of water into the
borehole (Ingersoll-Rand, 1985).
Tensile Strength
The greatest longitudinal stress a substance can bear with-
out pulling the material apart.
Test Hole
A hole designed to obtain information on ground-water
quality and/or geological and hydrological conditions (United
States Environmental Protection Agency, 1975).
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Thermoplastic Materials
Man-made materials often used for well casing that are
composed of different formulations of large organic molecules
that are softened by heating and hardened by cooling and can be
easily molded and extruded.
Thin-Wall Samplers
A hollow tubular sampling device that is pressed into the
formation below the drill stem to retrieve an undisturbed
sample.
Top-Head Drive
A drive for the drill stem where the bottom sub of the
hydraulic drive motor is connected directly to the drill rod.
Total Dissolved Solids (TDS)
A term that expresses the quantity of dissolved material in
a sample of water.
Transmissivity
The rate at which water is transmitted through a unit width
of an aquifer under a unit hydraulic gradient. Transmissivity
values are given in gallons per day through a vertical section of
an aquifer one foot wide and extending the full saturated height
of an aquifer under hydraulic gradient of 1 in the English
Engineering System; in the International System, transmissiv-
ity is given in cubic meters per day through a vertical section in
an aquifer one meter wide and extending the full saturated
height of the aquifer under a hydraulic gradient of 1 (Driscoll,
1986).
Tremie Method
Method whereby filter pack is emplaced or bentonite/
cement slurries are pumped uniformly into the annular space of
the borehole through the use of a tremie pipe.
Tremie Pipe
A device, usually a small-diameter pipe, that carries grout-
ing materials to the bottom of the borehole and that allows
pressure grouting from the bottom up without introduction of
appreciable air pockets (United States Environmental Protec-
tion Agency, 1975).
Turbidity
Solids and organic matter suspended in water.
Unconfined Aquifer
An aquifer not bounded above by a bed of distinctly lower
permeability than that of the aquifer and containing ground
water below a water table under pressure approximately equal
to that of the atmosphere.
Unconsolidated Formation
Unconsolidated formations are naturally-occurring earth
formations that have not been lithified; they may include
alluvium, soil, gravel, clay and overburden, etc.
Underreamer
A bit-like tool with expanding and retracting cutters for
enlarging a drill hole below the casing (Ingersoll-Rand, 1985).
Unified Soil Classification System
A standardized classification system for the description of
soils that is based on particle size and moisture content.
Uniformity Coefficient
A measure of the grading uniformity of sediment defined
as the 40-percent retained size divided by 90-percent retained
size.
Unit-Price Contracts
Drilling contracts that establish a fixed price for materials
and manpower for each unit of work performed.
Upgradient Well
One or more wells that are placed hydraulically upgradient
of the site and are capable of yielding ground-water samples
that are representative of regional conditions and are not affected
by the regulated facility (United States Environmental Protection
Agency, 1986).
Vadose Zone (Unsaturated Zone)
A subsurface zone above the water table in which the
interstices of a porous medium are only partially filled with
water (United States Environmental Protection Agency, 1986).
Vicksburg Sampler
A strong thin-walled sampler for use in stiff and highly
cemented Unconsolidated deposits.
Viscosity
The resistance offered by the drilling fluid to flow.
Volatile Organics
Liquid or solid organic compounds with a tendency to pass
into the vapor state (United States Environmental Protection
Agency, 1986).
Walking Beam (Spudding Beam)
The beam of a cable tool rig that pivots at one end while the
other end connected to the drill line is moved up and down,
imparting the "spudding" action of the rig.
Water Swivel
See Swivel, Water.
Water Table
The upper surface in an unconfined ground water body at
which the pressure is atmospheric (United States Environmental
Protection Agency, 1975).
Weight
Reference to the density of a drilling fluid. This is normally
expressed in either Ib/gal, Ib/cu ft, or psi hydrostatic pressure
per 1000 ft of depth.
Well
Any test hole or other excavation that is drilled, cored,
bored, washed, fractured, driven, dug, jetted or otherwise
constructed when intended use of such excavation is for the
location, monitoring, dewatering, observation, diversion, arti-
ficial recharge, or acquisition of ground water or for conducting
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pumping equipment or aquifer tests. May also refer to casing
and intake.
Well Cap
An approved, removable apparatus or device used to cover
a well.
Well Cluster
Two or more wells completed (screened) to different
depths in a single borehole or in a series of boreholes in close
proximity to each other. From these wells, water samples that
are representative of different horizons within one or more
aquifers can be collected (United States Environmental Pro-
tection Agency, 1986).
Well Construction
Water well construction means all acts necessary to obtain
ground water from wells.
Well Contractor
Any person, firm or corporation engaged in the business of
constructing, altering, testing, developing or repairing a well or
borehole.
Well Development
Techniques used to repair damage to the borehole from the
drilling process so that natural hydraulic conditions are re-
stored; yields are enhanced and fine materials are removed.
Well Evacuation
Process of removing stagnant water from a well prior to
sampling (United States Environmental Protection Agency,
1986).
Well Intake ( Well Screen)
A screening device used to keep materials other than water
from entering the well and to stabilize the surrounding forma-
tion.
Well Log
A record that includes information on well construction
details, descriptions of geologic formations and well testing or
development techniques used in well construction.
Well Point
A sturdy, reinforced well Screen or intake that can be
installed by driving into the ground.
Well Seal
An arrangement or device used to cover a well or to
establish or maintain a junction between the casing or curbing
of a well and the piping or equipment installed therein to prevent
contaminated water or other material from entering the well at
the land surface.
Well Vent
An outlet at or near the upper end of the well casing to allow
equalization of air pressure in the well.
Yield
The quantity of water per unit of time that may flow or be
pumped from a well under specified conditions.
Yield Point
A measure of the amount of pressure, after the shutdown
of drilling fluid circulation, that must be exerted by the pump
upon restating of the drilling fluid circulation to start flow.
Zone of Aeration
The zone above the water table and capillary fringe in
which the interstices are partly filled with air.
Zone of Saturation
The zone below the water table in which all of the inter-
stices are filled with ground water.
References
Bates, Robert L. and Julia A. Jackson, eds, 1987. Glossary of
geology; American Geological Institute, Alexandria,
Virginia, 788 pp.
Driscoll, Fletcher, G. 1986. Ground water and wells; Johnson
Division, St. Paul, Minnesota, 1089 pp.
Ingersoll-Rand, 1985. Drilling terminology; Ingersoll-Rand
Rotary Drill Division, Garland, Texas, 120 pp.
United States Environmental Protection Agency, 1975. Manual
of water well construction practices; United States
Environmental Protection Agency, office of Water
Supply EPA-570/9-75-001,156 pp.
United States Environmental Protection Agency, 1986. RCRA
ground-water monitoring technical enforcement guidance
document; Office of Waste Programs Enforcement,
Office of Solid Waste and Emergency Response,
Washington, D.C., OSWER-9950.1, 317 pp.
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