United States
Environmental Protection
Agency
Office of Solid Waste and
Emergency Response
January 2014
www.epa.gov/superfund
Superfund
Introduction to
Groundwater Investigations
Workbook
PERCHED
AQUIFER
SPRING


UNCONFINED
AQUIFER
CONFINED
AQUIFER

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TABLE OF CONTENTS
History of Colbert Landfill	Page 1
Problem 1: Cross Section Exercise	Page 3
Problem 2: Hydrogeological Exercise	Page 15
Parti: Determining Groundwater Flow Direction	Page 15
Part 2: Groundwater Gradient and Seepage Velocity
Calculation	Page 20
Part 3: Falling Head Test	Page 26
Problem 3: Performing an Aquifer Test	Page 29
Problem 4: Groundwater Investigation	Page 32
Glossary and Acronyms	Page 45
Selected Hydrogeology Slides and Equations	Page 53
Lecture Notes	Page 65

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HISTORY OF COLBERT LANDFILL, SPOKANE, WASHINGTON
The Colbert Landfill is located 2.5 miles north of the town of Colbert near Spokane, Washington,
and is owned by the Spokane County Utilities Department. This 40-acre landfill was operated from
1968 to 1986, when it was filled to capacity and closed. It received both municipal and commercial
wastes from many sources. From 1975 to 1980, a local electronics manufacturing company
disposed spent solvents containing methylene chloride (MC) and 1,1,1-trichloroethane (TCA) into
the landfill. A local Air Force base also disposed of solvents containing acetone and methyl ethyl
ketone (MEK). These solvents were trucked to the landfill in 55-gallon drums and poured down the
sides of open and unlined trenches within the landfill. Approximately 300-400 gallons/month of
MC and 150-200 gallons/month of TCA were disposed. In addition, an unknown volume of
pesticides and tar refinery residues from other sources were dumped into these trenches.
The original site investigation was prompted by complaints from local residents who reported TCA
contamination of their private wells. The population within 3 miles of the site is 1,500. In 1981, a
Phase I investigation was conducted: a Phase 2 was completed in 1982. Groundwater samples
collected from nearby private wells indicated TCA contamination at 5,600 |ig/L, MC contamination
at 2,500 |ig/L, and acetone at a concentration of 445 |ig/L. Investigation reports concluded that
drinking groundwater posed the most significant risk to public health. EPA placed the site on the
National Priority List (NPL) in 1983. Bottled water and a connection to the main municipal water
system was supplied to residents with high TCA contamination (above the MCL), and the cost was
underwritten by the potentially responsible parties (PRPs) involved.
Hydrogeological Investigation
The site lies within the drainage basin on the Little Spokane River, and residents with private wells
live on all sides of the landfill. The surficial cover and subsequent lower strata in the vicinity of the
site consist of glacially derived sediments of gravel and sand, below which lie layers of clay,
basaltic lava flows, and granitic bedrock. The stratigraphic sequence beneath the landfill from the
top (youngest) to the bottom (oldest) is:
Qa Alluvium or stream deposits composed of well-sorted and stratified silts, sands, and gravels
Qfg Upper sand and gravel glacial outwash and Missoula flood deposits which together form a
water table aquifer
Qglf Upper layers of glacial Lake Columbia deposits of impermeable silt and clay that serve as
an aquitard; lower layers of older glaciofluvial and alluvial sand and gravel deposits that
form a confined aquifer
Mcl Impermeable and unweathered Latah Formation of silt and clay
Kiat Fractured and unfractured granitic bedrock that serves as another confined aquifer
1

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In the upper aquifer (Qfg), which is 8-15 feet thick, groundwater flows from 4 to 13 feet per day
(ft/day). The lower confined sand and gravel aquifer (Qglf) varies from a few feet thick to 150 feet
thick and is hydraulically connected to the Little Spokane River. Groundwater in this aquifer flows
from 2 to 12 ft/day. To the northeast of the landfill, the upper aquifer is connected to the lower
aquifer. Both of these aquifers are classified as current sources of drinking water according to EPA
and are used locally for potable water. The area impacted by the site includes 6,800 acres and the
contamination plume extends 5 miles toward the town of Colbert. Of the contaminants present, 90
percent occur as dense, nonaqueous-phase liquids (DNAPLs) at the bottom of the upper aquifer,
and natural DNAPL degradation is slow. It has been estimated that only 10 percent of the solvents
have gone into solution, whereas the remainder occurs in pore spaces and as pools of pure product
above impermeable layers. The TCA plume in the upper aquifer has extended 9,000 feet in 8-10
years and it moves at a rate of 2-3 ft/day. The flow rate of the contamination plume in the lower
sand and gravel aquifer (Qglf) has not been calculated because of the complexity and variability of
the subsurface geology. However, TCA and MC have the highest concentrations in the lower sand
and gravel aquifer.
2

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PROBLEM 1: CROSS-SECTION EXERCISE
A.	Student Performance Objectives
1.	Draw a topographic profile of a specified area.
2.	Calculate a vertical exaggeration for a topographic profile.
3.	Obtain geological information from monitoring well logs.
4.	Use the GSA Munsell color chart and McCulloch geotechnical gauge to identify
rock sample colors and textures.
5.	Given a geologic map, interpret surface elevations of geologic formations.
6.	Draw a geologic cross section using monitoring well logs and a topographic
profile.
7.	Interpret subsurface geology to locate aquifers of concern and identify
discontinuities in geologic formations.
B.	Background Information
Students will examine rock/sediment samples labeled A, B, C, E, or F. These samples
represent rock/sediment samples from five different geologic formations encountered
during the installation of monitoring wells at, and in the vicinity of, the Colbert
Landfill site in Spokane, Washington. During the site investigation, these samples
were collected from cuttings generated by Roto-Sonic drilling. Each sample is also
oriented with an arrow that indicates the top.
C.	Geologic Cross-Section
1.	Using the GSA Munsell color chart and sample mask, match the overall color
of
the rocks, sand, clay, or gravel within the samples to the color chart. Do not
determine every color if a sample is multicolored, but look for key sediment
types or specific marker colors.
2.	Using McCulloch's geotechnical gauge, generally determine and match the
grain size of the sediments with the written descriptions. For example, actual
fine sand or coarse sand sizes can be found on the chart. Sediments larger than
coarse sand, such as gravel and cobbles, are NOT shown on the geotechnical
card. Using the geotechnical gauge and the sediment characteristics diagram
depicted in Figure 1, generally determine the degree of particle rounding and
sediment sorting. Well sorted means most particles are of similar size and
shape, whereas poorly sorted particles are of no particular size and vary greatly
in size and shape, such as sand mixed with gravel or cobbles.
3

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3.	Using the SAMPLES and well log together, match these descriptions and your
visual observations to a geologic formation listed on the Description of
Geologic Units for Cross-Section of Colbert Landfill. Then identify each
formation on the well logs in the space provided under the "STRATA"
column; for example, Kiat, sample F. START WITH WELL LOG #6, AND
PROCEED TO LOG #1. EACH SAMPLE REPRESENTS ONLY A
PORTION OF ONE ROCK FORMATION! Your instructor will discuss the
correct sample identification at the end of this portion of the exercise.
4.	Using the appropriate topographic maps and graph paper provided, locate Wells 6
through 1 along the top of the graph paper from left to right along profile line A-
A\ Determine the respective surface elevations of the wells (your instructor will
demonstrate this technique).
5.	Label the Y-axis of the graph paper to represent the elevation, starting from
2,100 feet at the top to 1,400 feet at the bottom. Each box on the graph
represents 20 FEET in elevation.
6.	Plot the location, depicting the correct surface elevation of each well on the
graph. Also determine and plot the elevations of SEVERAL EASILY
DETERMINED POINTS on the profile line between each of the wells in order
to add more detail to the profile. This will generate a series of dots representing
the elevations of the six wells and the other elevations you have determined.
Make sure to select contour lines that cross the profile line. The contour interval
of this topographic map is 20 feet.
7.	After plotting these elevations on the graph, connect them with a SMOOTH
CURVE, which will represent the shape of the topography from A-A'.
8.	Using the well logs previously completed and the colored geologic map, add the
existing geology and formation thickness to each well location. Each formation
thickness must be determined by the depth on the left side of the well log.
9.	Sketch in and interpret the geologic layers of the cross section, starting with the
lowest bedrock formation. Connect all of the same geologic formations, keeping
in mind that some formations have varying thicknesses and areal extent.
10.	Using available groundwater information shown on the well logs, locate the
shallow aquifer in the cross section.
11.	Using the completed cross section, locate potential sites for the installation of
additional monitoring wells or remediation wells and identify formation
discontinuities.
12.	Compare your interpretation with the "suggested" interpretation handed out by
the instructor.
4

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PL0TT|NG AT0P0GRAPH|C pROF1LE AND DRAWING A
GEOLOGIC CROSS SECTION, A SELECTED EXAMPLE
#
STEP #1, Determine Cross-Section Direction
= Monitoring Well
30 28

STEP #2, Collect Surficiaf Elevation Data
Elevations for this cross section
range from 24 to 30 feet; therefore,
select 23 to 31 feet for your
vertical scale at a spacing of
your choosing.
24 26 28 30 30 28 26


STEP #3, Choose Useful Vertical Scale
STEP #4, Draw Topographic Profile
STEP #4. Add Well Log thickness
STEP #5, Draw Geologic Cross-Section
5

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DESCRIPTION OF GEOLOGIC UNITS IN THE AREA OF
THE COLBERT LANDFILL - SPOKANE, WASHINGTON
MAP
SYMBOL
DESCRIPTION
Qa
Alluvium or stream deposits (Holocene) - composed of silt, grayish-orange
sand and gravel sediment that is well sorted and stratified. These deposits are
found in flood plains, river terraces, and valley bottoms.
Qfg
Flood deposits (Pleistocene) - poorly sorted, stratified mixture of boulders,
gray cobbles, dark gray well-rounded gravel, and coarse sand resulting from
multiple episodes of catastrophic outbursts from glacial-dammed lakes, such as
glacial Lake Missoula. The Little Spokane River Valley was one of the main
channelways for outburst flood waters from this ancient lake.
Qls
Alluvial fan deposits (Pleistocene) - composed of unstratified and poorly
sorted (heterogeneous and anisotropic) clay-, silt-, pink sand-, and gravel-size
sediment. Some fan deposits contain large blocks of gray basaltic rock as
much as 8 meters (26 feet) in diameter.
Qgif
Lacustrine deposits (Pleistocene) - composed of crumbly sediment of white-
clay, gray silt, and fine green sand, inter-bedded (mixed) with flood deposits
(Pleistocene), composed of poorly sorted, but stratified mixtures of boulders,
cobbles, gravel, and green sand.
Mvwp
COLUMBIA RIVER BASALT GROUP-TERTIARY
(MIOCENE)
Wanapum extrusive basalt flows - composed of dense, greenish-black, and
weathered basalt; some have a vesicular (mineral-filled gas bubble) texture.
Mcl
Latah Formation - white to yellowish gray siltstone and claystone, grayish-
green sandstone to lacustrine (lake) origin and grayish-orange sandstone from
fluvial (river/stream) depositional environments.

INTRUSIVE IGNEOUS ROCK-CRETACEOUS PERIOD,
MESOZOIC ERA
Kiat
Mount Spokane granite - massive, medium-grained pale, reddish-brown
granite that is present on Mount Spokane.

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Tetra Tech Inc.
Spokane, Washington
PROJECT NAME: Colbert Landfill
DRILLING COMPANY: Smith Drilling
BOREHOLE#: 1
SHEET; 1 of 1
PROJECT NUMBER: DNRSBOB
RIG TYPE: Rotosonlc
ELEVATION: 1920 AMSL
SITE NAME:
BORING TYPE:
MWQ PIEZOO
son
TOTAL DEPTH: 110 ft,
COUNTY: Spokane
DRILLER: D. Smith
STATIC WATER LEVEL: 10 ft.
CITY, STATE: Colbert, WA
LOGGED BY: D. Smith
BOREHOLE DIAMETER: 4"
PROJECT MANAGER:
SAMPLING METHOD: Rotosonlc
START DATE:
SUBSURFACE PROFILE
DEPTH
m
10
15
20
25
30
35
40"
45
50
55
60
65"
70 J
75-
so-
85"
90"
95""
100"
105-
110-
>-
cs
o
0 .
>
\jP v vy
3 „ O >
« 0 '
.. (T1 ^
J?
0 a
u a'
Of "3^
a "4
O
Jp
' 0<8 ;
> ft" >
DESCRIPTION
Poorly sorted but stratified
coarse sand and medium dark
gravel with some cobbles
Fractured granite
pale reddish brown
QJ
UJ
> -3-
o £
O
m
Q£
FINISH DATE;
WELL CONSTRUCTION
Dense granite, pink
minor fractures
100
NOTES ft - feci
amsl - above mean sea level
bgs- be I oh mound surface
7

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Tfe
Tetra Tech Inc.
Spokane, Washington
PROJECT NAME: Colbert Landfill
DRILLING COMPANY; Smith Drilling
BOREHOLE m 2 SHEET: 1 of t
PROJECT NUMBER; DNR560S
RIG TYPE: Rotosonic
ELEVATION: 1955 AMSL
SITE NAME:
BORING TYPE:
MWU PIEZOD SBD
TOTAL DEPTH: 250 ft
COUNTY: Spokane
DRILLER: D. Smith
STATIC WATER LEVEL; m ft.
CITY, STATE: Colbert, WA
LOGGED BY: O. Smith
BOREHOLE DIAMETER: 4"
PROJECT MANAGER:
SAMPLING METHOD: Rolosonlc
START DATE: FINISH DATE:
SUBSURFACE PROFILE
WELL CONSTRUCTION
DEPTH
(FT)
s
s
o
32
DESCRIPTION
§

51
loi
15i
201
251
30"=
35i
40-f
45i
50^
55"=
601
65'"i
701
75-=
80 4
85-1
90-i
95-|
« 0 •»
OP ">5 OF
> 0 V <
><»V<
*> o«
J? "vSoF
' °°G ' 4
<5 .
? 00 ? r
9 s c
op "£ o.-
' O°0 ' £
Poorly sorted sand, gravel, and
some cobbles
gravel, well rounded medium
gray
sand, coarse grained stratified
2 layers of same
100

105 ~P
110-1
115-1
120"!
125-1
130*1
135-f
140*1
145-1
150 "I
155*1
160*1
165-1
170-1
175-I
y//s//A
< / >/ */,
- V, v V
'//////,
'//////
*i
Stratified clay and poorly sorted
sand and gravel
clay-white, crumbly with thin
sand layers
100
185 "I
190-1
195 "1
200 *1
205-1
2101
215-1
%, . .A -
1 j, v !¦»
1 f . 4
VhViV
1
3> " *
¦>-1 J * 1 «i
v J V ' /
* r „ ' "»*
1 S I
¦ «t ¦" ¦ '
Weathered granite, pale reddish
brown
50
225-1
230-1
235 4
240 4
2451
?50-
S
1 1 » i
' 1 t ^ i
t -
» i. * »"
*1 ^ > - t
fc,i' ^ - X
Dense granite
90
NO ICS It -lu
niml - abc
bsK- beltn
Cl
vt mean «level
ground -.ui lace

8

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mmm »	maim	¦ »
Tetra Tech Inc.
Spokane, Washington
PROJECT NAME: Colbert Landfill
DRILLING COMPANY: Smith Drilling
BOREHOLE #: 3
SHEET: 1 of 1
PROJECT NUMBER: DNRS606
RIG TYPE: Rotosonic
ELEVATION: 1928 AMS
SITE NAME:
BORING TYPE:
MW0 PiEZOO SB ~
TOTAL DEPTH: 320 ft.
COUNTY: Spotane
DRILLER: 0. Smith
STATIC WATER LEVEL: 50 ft
CITY, STATE: Colfcort, WA
LOGGED BY: D, Smith
BOREHOLE DIAMETER: 4"
PROJECT MANAGER:
SAMPLING
: Rotosonic
START DATE:
FINISH DATE:
SUBSURFACE PROFILE
DEPTH
(FT)
8
DESCRIPTION
WELL CONSTRUCTION
"T?i
<3'n -5*
0 -
5
10
15
20
25
30
35
40
45
50	^ .
65#'°'S
70t ^ '
i tJC k?
, 5* • 
-------
Tetra Tech Inc.
Spokane, Washington
PROJECT NAME: Colbert Landfill
DRILLING COMPANY; Smith Drilling
BOREHOLE#: 4
SHEET: 1 of 1
PROJECT NUMBER: DNR5806
RIG TYPE: Rotosonic
ELEVATION: 186S AMSL
SITE NAME:
BORING TYPE:
MWQ PIEZOO SBO
TOTAL DEPTH: 320 ft.
COUNTY: Spokane
DRILLER: D. Smith
STATIC WATER LEVEL: SS ft
CITY, STATE: Colbert, WA
LOGGED BY: D. Smitfl
BOREHOLE DIAMETER: 4"
PROJECT MANAGER:
SAMPLING METHOD: Rotosonic
START DATE:
FINISH DATE:
SUBSURFACE PROFILE
DEPTH
jFT)
DESCRIPTION
WELL CONSTRUCTION
f *°0
Stratified 2 layers, poorly sorted
gray well rounded gravel and
coarse sand, minor cobbles
f a 5
45- a (J
50- ¦
190
y o ?
' «" >
Stratified white clay and poorly
sorted sand and gravel
100
siltstone to claystone with
sandstone layers, grades to
sandstone white to yellowish
gray sandstone, white to It, tan
too
Weathered granite pale reddish
brown
320
Dense pate reddish brown
granite

100
NOTES: ft. - feet
amsl - above mean sea level
bgs- below ground surface
10

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PROJECT NAME; Colbert Landfill
DRILLING COMPANY; Smith Drilling
BOREHOLE ft 5
SHEET: 1 of 1
PROJECT NUMBER; ONR560S
RIG TYPE; Rotosonic
ELEVATION: 1680 AMSL
SITE NAME:
BORING TYPE:
MWLi P1EZOO SBO
TOTAL DEPTH; 170 ft.
COUNTY: Spokane
DRILLER! D, Smith
STATIC WATER LEVEL: 15 ft.
CITY, STATE: Colbert, WA
LOGGED BY: D. Smith
BOREHOLE DIAMETER: 4"
PROJECT MANAGER:
SAMPLING METHOD: Rotosonic
START DATE:
FINISH DATE;
Tetra Tech Inc.
Spokane, Washington
SUBSURFACE PROFILE
DEPTH
(FT)
>-
g
c!
DESCRIPTION
WELL CONSTRUCTION
10
15
20
25
30
35
40'
45'
50'
55
60'
65-
70-=
75
BO
as
90
05
100
105
110
115
120
125
130
135
140
145
ISO
155
160
165
170
O O. O
0-0--0
ore
Q'O.-P
Well sorted, fineing upward
gravel, sand, silt
gravels well rounded
100
: . t. ¦ s
.• • o..
*3 •, ,¦ •£> ^
® . ¦ CI 13
Poorly sorted sand, gravel, and
cobbles, minor boulders-gravel
well rounded, Dk. gray cobbles
well rounded, gray, sand course,
yellowish fan
too
white to yellowish gray claystone
with thin layers of grayish green
sandstone
-.si ¦ • i/ I'.-J
¦>%'
- 'Is r'.M
100
Weathered granite, reddish
brown
Dense Spokane granite
100
NOTHS: ft, - li-el
amsl • above mean sen level
bp- bulmv cround surface
11

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Tetra Tech Inc.
Spokane, Washington
PROJECT NAME: Colbert Landfill
DRILLING COMPANY; Smith Drilling
BOREHOLE #: 6
SHEET: 1 of 1
PROJECT NUMBER: DNR5606
RIG TYPE: Rotosonlc
ELEVATION: 2000 AMSL
SITE NAME:
BORING TYPE:
PIEZO D SBQ
TOTAL DEPTH: 300 ft.
COUNTY: Spokane
DRILLER: D. Smith
STATIC WATER LEVEL: 45 ft
CITY, STATE: Colbert, WA
LOGGED BY: D. Smith
BOREHOLE DIAMETER: 4,f
PROJECT MANAGER:
SAMPLING METHOD: Rotosonic
START DATE:
SUBSURFACE PROFILE
DEPTH
(FT)
DESCRIPTION
o £.
o

FINISH DATE:
WELL CONSTRUCTION
¦JP of
up 'C
-w *J*
O -n-
A
S///A
H/%'
Sand, gravel, and cobbles-poorly
sorted-two layers, sediments
well rounded
too
White clay with fine green sand
layers and gray silt-stratified over
poorly sorted boulders, cobbles,
gravei, and sand
Weathered granite
Dense granite

100
75
100
NO ITS ft - Icet
jiiirI - abo\ c mean sea level
tigs- below ground surface
12

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5
1 S		 t ^
¦" t -
' •
'A ¦ ;
i ?
v	
•¦ .	t« | ; ¦ 		;. i
i	*.&	?
»
fmsrr

"A—r ^
ii
i
_r
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Ljag^ggs


S.
£M\x;

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COLBERT LANDFILL
1" = 80' Vertical Scale
1" = 2,000' Map Scale
V.E .=
V.E.=
V. Scale
H. Scale
1 '780'
172000'
tM00
Profile of Colbert Landfill,
Spokane, Washington
V.E = 25

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PROBLEM 2: HYDROGEOLOGICAL EXERCISES
PART 1. DETERMINING GROUNDWATER FLOW DIRECTION
A.	General Discussion
Methods for determining the direction of groundwater flow depend on the number of wells
present on a particular site. When a site consists of only a few wells, a mathematical or
graphical three-point problem can be used as shown in sections B and C. It is important to
note that three-point problems can also be used to calculate the slope of the groundwater
surface by dividing the difference in head (Hi - H3) by the measured map distance. When
a site has a large number of wells, the slope of the groundwater surface can be calculated
and depicted graphically by constructing a flow net, explained further in Part 2, section A.
B.	The Mathematic Three-Point Problem for Groundwater Flow
Groundwater-flow direction can be determined from water-level measurements made on
three wells at a site (Figure 1).
1.	Given:
Well Number	Head (meters)
1	26.28
2	26.20
3	26.08
2.	Procedure:
a.	Select water-level elevations (head) for the three wells depicted in
Figure 1. Label as Hi, H2; and H3 in descending order.
b.	Determine which well has a water-level elevation between the other wells
(Well 2).
c.	Draw a line between Wells 1 and 3. Note that somewhere between these
wells is a point, labeled A in Figure 2, where the water-level elevation at
this point is equal to Well 2 (26.20 m).
d.	To determine the distance X from Well 1 to point A, solve the following
equation (see Figure 3, 4, and 5):
Hi - H, Hi - H?
Y = X
e.	Distance Y is measured directly from the map
(200 m) on Figure 3.
f.	After distance X is calculated, groundwater-flow direction based on the
water-level elevations can be constructed 90° to the line representing
equipotential elevation of 26.20 m (Figure 6).
15

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H, WELL 1
)- (Head, 26.28 m)
WELL 2
(Head, 26.20 m)
WELL 3
(Head, 26.08 m)
METERS {scale approximate)
FIGURE 1. Label and assign water-level elevations for each well.
N
R
J WELL 1
t

* (Head, 26.28 m)
1
WELL 2
(Head, 26.20 m)

1^^*^ Point A
1
1
0 25 50 1|0
I
-^-WELL 3
n3 (Head, 26.08 m)
METERS (scale approximate)


FIGURE 2. Approximate where 26.20 m crosses the line between Well 1 and Well 3 (Point A).

-------
N
t
WELL 2
(Head, 26.20 m)
H^"
0 25 50 100
METERS (scale approximate)
M1 WELL 1
(¦y
t)r
X
U
(Head, 20,28 m)
j ^ point A
I
I
WELL 3
H3 (Head, 26,08 m)
FIGURE 3. Diagram showing how to obtain values for the variables in the three-point equation.
H, - H3
H, - H2
(26.28 - 26.08)
(26.28 - 26.20)
200 m
X
0.2
0.08
200 m
X
X =
(0.08 x 200)

0.2
X =
80 m
NOTE: Measure distance of X from H, using scale provided.
FIGURE 4, Solution for the three-point equation.
17

-------
N
t

WELL 1
(Head, 26.28 m)
WELL 2
(Head, 26,20 m)
80 m
Si.
,2.8
.20^



0 25 50 100
WELL 3
(Head, 26.08 m)
METERS (seals approximate)
FIGURE 5. Applying the three-point solution to the diagram to determine Point A.
N
t

WELL 2
{Head, 26.20 m)
WELL 1
(Head, 26.28 m)
.26-2°
Groundwater
Flow Direction
0 25 50 100
WELL 3
(Head, 26.08 m)
METERS (scale approximate)
FIGURE 6, Depiction of groundwater flow direction, 90° to the 26.20 m contour line.

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C. The Graphical Three-Point Problem for Groundwater Flow
Groundwater-level data can be used to determine direction of groundwater flow by
constructing groundwater contour maps and flow nets. To calculate a flow direction, at least
three observation points are needed. First, relate the groundwater field levels to a common
datum - map datum is usually best - and then accurately plot their position on a scale plan.
Second, draw a pencil line between each of the observation points, and divide each line into
a number of short, equal lengths in proportion to the difference in elevation at each end of
the line (Figure 7). The third step is to join points of equal height on each of the lines to
form contour lines (lines of equal head). Select a contour interval that is appropriate to the
overall variation in water levels in the study area. The direction of groundwater flow is at
right angles to the contour lines from points of higher head to points of lower head (Figure
8).
N
t
26.26
26.24
26.22
26.20
26.18
26.16
..26.10
WELL 2
(Head, 26.20 m)
H
WELL 1
(Head, 26.28 m)
WELL 3
(Head, 26.08 m)
METERS (scale approximate)
FIGURE 7. Steps l and 2 for the graphical three-point problem.
N
t
WELL 2
{Head, 26.20 m)

0 25 50
WELL 1
(Head, 26.28 m)
6:26
2&24-
_-26.-20
' CONTOUR LINES
— V ___ J_26.-i6"~
' V" .2SA4-
,.26-12-
100
WELL 3
{Head, 26.08 m)
METERS (scale approximate)
FIGURE S, Step 3 for the graphical three-point problem.
19

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PART 2. GROUNDWATER GRADIENT and SEEPAGE VELOCITY
CALCULATION
A.	Purpose
This part of the exercise uses basic principles defined in the determination of
groundwater-flow directions. Groundwater gradients (slope of the top of the
groundwater table) will be calculated as shown in the three-point problem.
The three point procedure can be applied to a much larger number of water-level
values to construct a groundwater-level contour map. Locate the position of each
observation point on a base map of suitable scale and write the water level next to
each well's position. Study these water-level values to decide which contour lines
would cross the center of the map. Select one or two key contours to draw in first.
Once the contour map is complete, flow lines can be drawn by first dividing a
selected contour line into equal lengths. Flow lines are drawn at right angles from
this contour, at each point marked on it. The flow lines are extended until the next
contour line is intercepted, and are then continued at right angles tot his new contour
line. Always select a contour that will enable you to draw the flow lines in a
downgradient direction.
B.	Key Terms
•	Head - The energy contained in water mass produced by elevation, pressure,
and/or velocity. It is a measure of the hydraulic potential due to pressure of
the water column above the point of measurement and height of the
measurement point above datum which is generally mean seal level. Head is
usually expressed in feet or meters.
•	Contour line - A line that represents the points of equal values (e.g.,
elevation, concentration).
•	Equipotential line - A line that represents the points of equal head of
groundwater in an aquifer.
•	Flow lines - Lines indicating the flow direction followed by groundwater
toward points of discharge. Flow lines are always perpendicular to
equipotential lines. They also indicate direction of maximum potential
gradient.
20

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1019
96.2
94.8
99.6
99.1
102.0
100.8
400
FEET (scale approximate)
102.4
FIGURE 9. Well locations and head measurements
89.4	88.9
•yp*
91.
101.9
101.8

-------
¦4
101,9
100'
~
~
96,2
95'
\ 94.8
90'

•A*
89.4
, 88.9
mS
TfF


*|J|"
V99.6

~
99.1


X 94-8
4-
+ 91.0
~
102.0
0
Li!

~
100.8
400
J






!


102.4
101.9
+
101.8
FEET (scale approximate)






FIGURE 10. Equipotential lines with well head measurements
22

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90!
100'
89,4
88.9
101.9
96.2
94.8
94,8,
99.6
91.0
99.1
102.0
100.8
102.4
101.8
1019
FEET {scale approximate)
FIGURE 11. Flow lines added to equipotential lines and calculation of hydraulic gradient
Calculation of Hydraulic Gadient
Head at A= 100'(H,)
Head at B = 90' (H2)
Measured distance between the points is 600' (L).
Head at point A minus head at point B divided by the distance between the points
equals hydraulic gradient (slope from point A to point B).
100 feet - 90 feet 10
¦	:	:	 = 	 = .011 feet/foot
600 feet	600
23

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Calculation of Seepage Velocity (Vs)
Vs = KI
Ne
Given a hydraulic conductivity (K) of 5 ft/day and an effective porosity (Ne) of 15%;
solve the amount of time (in Days) for groundwater to travel from point A to point B.
Vs = KI
Ne
Vs = (5 ft/day) (0.017 ft/ft)
0.15
Vs = 0.56 ft/day
Given a distance between Point A to B = 600 feet and using the velocity equation of
(Vs) (Time) = Distance
Time	= Distance
Vs
Time
600 ft
1071 Days or 2.9 Years
0.56 ft/day
Key
Ne
Vs
K
Seepage velocity
Hydraulic conductivity
Gradient
Effective porosity
24

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Groundwater Gradient, Colbert Landfill
Overlay the transparent sheet on top of the Colbert Landfill topographic map. Tape
down to hold in place, and mark a few reference points to ensure correct placement
throughout the exercise (i.e., make a "+" on an intersection or reference line on the
map).
Select an appropriate contour interval that fits the water levels available and the size
the map. Fifty-foot contour intervals should be appropriate for this problem.
Draw the equipotential lines on the map interpolating between water-level
measurements. Paragraph two of the Purpose also explains this technique.
Construction flow lines perpendicular to the equipotential lines drawn in step 4 and
discussed in paragraph three of Purpose.

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PART 3. Falling Head Test Exercise
A.	Student Performance Objectives
1.	Perform a falling head test on geologic materials.
2.	Calculate total porosity, effective porosity, and estimated hydraulic conductivity.
B.	Perform a Falling Head Test
1.	Set up burets using the stands and tube clamps.
2.	Clamp the rubber tube at the bottom of the burets using the hose clamp. Fold the
rubber hose to ensure a good seal before clamping (to help eliminate leaking
water).
3.	Position the small, round screen pieces in the bottom of the burets. Use the tamper
to properly position the screens.
4.	Measure 250 ml of colored water in the 500 ml plastic beaker.
5.	Pour the water slowly into the buret to avoid disturbing the seated screen.
6.	Measure 500 ml of gravel or sand material in the 500 ml plastic beaker.
7.	Pour the gravel or sand slowly into the water column in the buret to prevent the
disturbance of the screen traps and to allow any trapped air to flow to the surface
of the water in the buret.
8.	Add additional measured quantities of water or gravel/sand as needed until both
the water and sediment reach the zero mark on the buret. To calculate the final
total volumes of water and sediment, add the volumes of additional water and
gravel/sand to the initial volumes of 250 and 500 ml of water and sediment. The
total volumes of water and sediment are designated W and S respectively.
9.	Measure the static water level in the buret to the base of the buret stand. This is
the total head of the column of water at this elevation. This measurement is
designated h0.
10.	Place a plastic, 500 ml graduated beaker below the buret. (The beaker will be used
to collect the water drained from the buret.) The volume of water in the beaker is
designated Wd.
11.	Undo the clamp and simultaneously start the timer to determine the flow rate of
water through the buret. When the drained water front reaches the screen, stop the
timer, clamp the buret hose, and record the elapsed time. Also record the volume
of water drained during this time interval. This time is designated t.
26

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12.	Allow the water level in the buret to stabilize. Measure the length from this
level to the base of the buret stand. This is the total head of the water column
at this elevation after drainage has occurred. This measurement is designated
hi.
13.	Subtract the measurement at hi from the height measurement at h0. This length
is designated L.
14.	The porosity in the sediment of each buret is the volume of water necessary to
fill the column of sediment in the buret to the initial static water mark at h0
divided by the sediment volume (S). This value is total porosity and is
designated N.
15.	The effective porosity is estimated by dividing the volume of drained water by
the sediment volume. Effective porosity is designated n.
16.	Compare the initial volume of water (W) in the column before draining with
the drained volume (Wd). The difference represents the volume of water
retained (WR), or the specific retention. The volume drained represents
specific yield. To determine the percent effective porosity, divide the volume
of drained water by the volume of total sediment volume.
17.	The equation to estimate the hydraulic conductivity (K) of each buret column
is derived from falling head permeameter experiments. The equations for this
exercise are depicted below.
27

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TABLE 2. TOTAL HEAD WORKSHEET
Sample Number



Volume Sediment (S)



Volume Water (W)



Volume Drained Water (Wd)



Volume Retained Water



Total Porosity Calculated (N)



Effective Porosity Calc. (n)



Length (h0 -hi)



Time (t)



Initial Head (Ho)



Final Head (Hi)



In (h0/hi)



Est. Hydraulic Conductivity (K)



Total Porosity	Effective Porosity	Est. Hydraulic Cond.
N = W	n = Wd	K = \23 xLl x In (h0/hi)
S	S	[ t ]
28

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PROBLEM 3: PERFORMING AN AQUIFER TEST
JACOB TIME-DRAWNDOWN METHOD
Background Information
Each student will be given a sheet of semilogarithmic graph paper. Then, they should
follow these directions:
1.	Orient the semi-log paper, so the three-hole punches are at the top of
the page. Label the long horizontal logarithmic axis (the side with the
punched holes) of the graph paper t-times (minutes). Leave the first
numbers (1 through 9) as is. Mark the next series of heavy lines from
10 to 100 in increments of 10 (10, 20, 30, etc.). Mark the next series
from 100 to 1000 in increments of 100 (100, 200, 300, etc.).
2.	Label the short vertical arithmetic axis s-drawdown (feet). This will be
the drawdown (s) measured from the top of the casing (provided in
Table 1) mark off the heavy lines by tens, starting with 0 at the top,
then 10, 20, 30, 40 50, 60 and 70 (the bottom line). Each individual
mark represents 1 foot.
3.	Plot the data in Table 1 on the semilogarithmic paper with the values
for drawdown on the arithmetic scale and corresponding pumping times
on the logarithmic scale.
4.	Draw a best-fit straight line through the data points.
5.	Compute the change in drawdown over one log cycle where the data
plot as a straight line.
6.	Using the information given in Table 1 (Q = 109 gpm and b = 20 feet)
and Jacob's formula shown below, calculate the value for hydraulic
conductivity.
AS = ft
T = 35Q	T = ft2/day
AS
K =_T
b
K = ft/day

-------
TABLE 1. PUMPING TEST DATA
PUMPING TIME (t)
DRAWDOWN (h„- h)
(minutes)
MEASURED FROM TOP OF CASING
Q = 109 gpm
B - 20 ft
0
6.1
1
6.5
2
7.5
3
8.0
4
8.6
5
9.5
6
10.5
7
11.2
8
12.0
9
13.0
10
14.0
11
15.5
12
17.0
13
18.0
14
19.3
15
20.5
18
23.5
20
25.2
22
26.7
24
28.2
26
29.5
28
30.5
32
32.0
35
34.5
40
36.6
45
38.5
50
40.5
55
42.0
60
43.5
90
50.1
120
54.8
30

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PROBLEM 3: PERFORMING AN AQUIFER TEST
HVORSLEV SLUG TEST
A slug test is performed by lowering a metal slug into a piezometer that is screened in a silty
clay aquifer. The inside diameter of both the well screen and the well casing is 2 inches. The
borehole diameter is 4 inches. The well screen is 10 feet in length. The following data were
obtained when the slug was rapidly pulled from the piezometer:
TABLE 2. SLUG TEST DATA
ELAPSED TIME
DEPTH TO WATER
CHANGE IN WATER

(minutes)
(feet)
LEVEL h (feet)
hh„
Static level
13.99


0
14.87
0.88 (h0)
1.000
1
14.59
0.60
0.682
2
14.37
0.38
0.432
3
14.20
0.21
0.239
3
14.11
0.12
0.136
5
14.05
0.06
0.068
6
14.03
0.04
0.045
7
14.01
0.02
0.023
8
14.00
0.01
0.011
9
13.99
0.00
0.000
The time for the head to rise or fall to 37 percent of the initial value is Ta. The following
values are obtained from the geometry of the piezometer:
r = 0.083 feet
R= 0.166 feet
L= 10.0 feet
1 cm/sec = 2835 ft/day
The ratio L/R is 60.24, which is more than 8, so the following equation is used:
ja _ r2//?(L/R)
2LT0
31

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PROBLEM 4. GROUNDWATER INVESTIGTION
BETTENDORF, IOWA
A.	Student Performance Objectives
1.	This will be your final examination. Based on your performance, you and your
group will be evaluated on your findings and conclusions that you presented to
your peers.
2.	Perform a site investigation using soil gas surveys and monitoring wells.
3.	Determine the source(s) of hydrocarbon contamination at a contaminated site.
4.	Present the results of the field investigation to the class.
5.	Justify the conclusions of the field investigation.
B.	Desktop and Other Background Information
History of the Leavings' Residence
On October 12, 1982, the Bettendorf, Iowa, fire department was called to the Leavings'
residence with complaints of gasoline vapors in the basement of the home.
On October 16, 1982, the Leavings were required to evacuate their home for an indefinite
period of time until the residence could be made safe for habitation. The gasoline vapors
were very strong, so electrical service to the home was turned off. Basement windows
were opened to reduce the explosion potential.
32

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Pertinent Known Facts
The contaminated site is in a residential neighborhood in Bettendorf, Iowa. It borders on
commercially zoned property, which has only been partially developed to date. The
residential area is about 10 years old and contains homes in the $40,000 to $70,000 range.
There was apparently some cutting and filling activity at the time the area was developed.
Within Vi mile to the northwest and southwest, 11 reported underground storage tanks
(USTs) are in use or have only recently been abandoned:
*	Two tanks owned and operated by the Iowa Department of Transportation
(IDOT) are located 1000 ft northwest of the site.
*	Three in-place tanks initially owned by Continental Oil, and now by U-Haul,
are located 700 ft southwest of the site. According to the Bettendorf Fire
Department (BFD), one of the three tanks reportedly leaked.
*	Three tanks owned and operated by an Amoco service station are located 1200
ft southwest of the site. BFD reports no leaks.
*	Three tanks owned and operated by a Mobil Oil service station are located 1200
ft southwest of the site. BFD reports no leaks.
Neighbors that own lots 8 and 10, which adjoin the Leavings residence (Lot 9), have
complained about several trees dying at the back of their property. No previous
occurrences of gasoline vapors have been reported at these locations.
The general geologic setting is Wisconsin loess sediments mantling Kansan and
Nebraskan glacial till. Valleys may expose the till surface on the side slope. Valley
sediment typically consists of alluvial silts.
Previous experience by your environmental consulting firm in this area includes a
geotechnical investigation of the hotel complex located west of Utica Ridge Road and
northwest of the Amoco service station. Loess sediments ranged from 22 ft thick on the
higher elevations of the property (western half) to 10 ft thick on the side slope. Some silt
fill (5-7 ft) was noted at the east end of the hotel property. Loess was underlain by a
gray, clayey glacial till which apparently had groundwater perched on it. Groundwater
was typically within 10-15 ft of ground surface. This investigation was performed 8
years ago and nothing in the boring logs indicated the observation of hydrocarbon vapors.
However, this type of observation was not routinely reported at that time.
Other projects in the area included a maintenance yard pavement design and construction
phase testing project at the IDOT facility located northwest of the Leavings residence.
Loess sediments were also encountered in the shallow pavement subgrade project
completed 3 years ago. Consulting firm records indicated that the facility manager
reported a minor gasoline spill a year before and that the spill had been cleaned up when
the leaking tank was removed and replaced with a new steel tank. The second tank at the
IDOT facility apparently was not replaced at that time.
33

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Results of Site Interviews
•	Lot 9 (THE Leavings' residence): Observations outside the residence indicate that
the trees are in relatively good condition. The house was vacant. Six inches of free
product that looks and smells like gasoline was observed in the open sump pit in the
basement. The power to the residence was turned off, so the water level in the sump
was allowed to rise. The fluid level in the sump was about 3 feet below the level of
the basement floor.
•	Neighbors (Lots 8 and 10): These property owners reported that several trees in
their backyards died during the past spring. They contacted the developer of the area
(who also owns the commercial property that adjoins their lots) and complained that
the fill that was placed there several years ago killed some of their trees. No action
was taken by the developer. Both neighbors said that when the source of the as was
located, they wanted to be notified so they could file their own lawsuits. The
neighbors also noted that this past September and October were unusually wet (lots of
rainfall).
•	IDOT: The manager remembers employees from your firm testing his parking lot.
He reported that one UST was replaced in 1979, whereas the other tank was installed
when the facility was built in 1967. Both of the original tanks were bare metal tanks.
The older replaced tank always contained gasoline, but the newer one contains diesel
fuel. No inventory records or leak testing records are available. The manager stated
that he has never had any water in his tanks. He will check with his supervisor to
have the USTs precision leak tested.
•	U-Haul: The manager said that the station used to be a Continental Oil station with
three USTs. The three USTs were installed by Continental in 1970 when the station
was built. Currently, only one 6000-gal UST (unleaded) remains in service for the U-
Haul fleet. This tank was found to be leaking a month ago, but the manager does not
know how much fuel leaked.
•	Mobil: The manager was pleasant until he found out the purpose of the interview.
He did state that he built the station in 1970 and installed three USTs at that time. He
would not answer any additional questions.
•	Amoco: The manager was not in, but an assistant provided his telephone number. In
a telephone interview, the manager said he was aware of the leaking tank at the U-
Haul factory and was anxious to prove the product was not from his station. He said
they installed three USTs for unleaded, premium, and regular gasoline in 1972. An
additional diesel UST was installed in 1978. The tanks are tested every 2 years using
the Petrotite test method. The tanks have always tested tight. No inventory control
system is being used at present. He stated that if monitoring wells were needed on
his property, he would be happy to cooperate.
34

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• Developer (Mr. M. Forester): Mr. Forester bought the property in question in the
1960s. He developed the residential area first and some of the commercial
development followed. About 40 acres remain undeveloped to date. He plans to
build a shopping center on the remaining 40 acres in the future.
Mr. Forester obtained a lot of cheap dirt and fill when the interstate cut went through
about V2 mile west of the property in the late 1960s. He filled in a couple of good-
sized valleys at that time. He has a topographic map of the area after it was filled.
He stated that he will cooperate fully with any investigation. If any wells are needed
on the property, he would like to be notified in advance. There are no buried utilities
on the property except behind the residential neighborhood.
Review of Bettendorf City Hall Records
An existing topographic map and scaled land use map are included in this exercise.
Ownership records indicate the land was previously owned by Mr. and Mrs. Ralph Luckless. The
city hall clerk stated that she had known them prior to the sale of the farm in 1964. Zoning at that
time was agricultural only. The section of the farm now in question was primarily used for grazing
cattle because it was too steep for crops. The clerk remembered a couple of wooded valleys in that
same field. She also remembered a muddy stream that used to run where Golden Valley Drive is
now and that children used to swim in it. She also stated that one valley was between Golden Valley
Drive and where all the fill is now (near U-Hal and Amoco).
The current owner of the underdeveloped property is Mr. M. Forester, a developer with an Iowa
City, Iowa address.
There is no record of storm of sanitary sewer lines along Utica Ridge Road south of Golden Valley
Drive. Storm and sanitary sewer lines run along Spruce Hills Drive.
Iowa Ecological Survey Information
There are no records of any wells in the section.
In an adjoining section, wells indicate top of bedrock at about 650 feet mean sea level (MSL).
The uppermost usable aquifer is the Mississippian-age limestone for elevations from 350 feet to
570 feet MSL. The materials overlying the Mississippian are Pennsylvanian shales and
limestone.
Soil Conservation Survey Maps
The 1974 edition indicates "Made Land" over nearly all of the area not designated as commercial
zone. Made Land normally indicates areas of cut or fill.
35

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1
2
mmmm
3
4
5
6
7
8
9
10
11
z
13
14
15
16
36
SCALED LAND USE MAP
-j-, Iowa DOT :
a Maintenance
	Facility
Hotel
Complex
Leavings
(Zoned Commercial)


Amoco
U Haul
^~^Pnve
Mobil Dil

-------
A B C D E F G H 1 J K L
PREDEVEL'OPMENT
TOPOGRAPHIC MAP
37

-------
A B C D E F G H I J K L
i EXISTING I -|
TOPOGRAPHIC MAP
38

-------
ASSIGNMENT: FIELD INVESTIGATION
TABULATION OF FEES FOR FIELD INVESTIGATION GROUP
\yokksiii-:kt#i
# IM IS
COST
TOTAL
Recommendations for making residence habitable
1 each
$500 LS
(lump sum)
$
Soil gas survey - mobilization fee
1 each
$500 LS
$
Soil gas survey

$1500/ac

Monitoring wells - mobilization fee
1 each
$500 LS
$
2" PVC
15 ft screen - 25 ft deep

$1200 ea

2" stainless steel
15 ft screen - 25 ft deep

$1700 ea
$
Well security - locking protector pipe

$300 ea
$
Field investigation engineering analysis and
report
1 each
15%
$2000 min
$
TOTAL COST


$
SITE INVESTIGATION FIELD ACTIVITIES
AT BETTENDORF, IOWA
Each team is to perform a site investigation. (The instructors will select the groups.) All
public written information has been provided, and we expect your team to gather field data and
other information from us in order to identify the responsible parties for the contamination at the
Leavings' residence. Your group will need to select where to install monitoring wells and
conduct soil gas surveys. Use the table on page 10 for monitoring well data and the base map on
page 11 for soil gas survey results.
The following caveats are a guide of activities for your group to follow while completing this
task.
1.	Teams will be determined by the instructors.
2.	Review all prior desktop information.
3.	Organize your effort in gathering more data and information.
a.	Determine the location of the groundwater table by installing monitoring wells.
b.	Determine source(s) of contamination and define the shape of the contaminant
plume(s) on top of the groundwater table using
i.	Data from monitoring wells
ii.	Soil gas survey results
c.	Construct a cross section normal to groundwater flow.
d.	Determine hydraulic conductivity using slug test data.
e.	Calculate transport time of contaminants.
f.	Calculate cost of investigation.
39

-------
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
40
CDEFGHI JKL
GROUP
1
-EE*
EZZI
Soil gas survey
hit"+" miss
it M
Monitoring well
loess
alluvium
non-detection
free product
gw elevation

-------
GROUP
MONITORING WELLS
WELL NUMBER
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
GRID LOCATION




















FILL




















LOESS




















ALLUVIUM




















TILL




















NON-DETECTED




















DISSOLVED PRODUCT




















FREE PRODUCT




















WATER ELEVATION




















41

-------
1
?
Jmwk
3
K
*»#
6
7
8
9
10
11
12
13
14
I o
16
ABCDEFGH I JKL
GROUP
I	
Scale: |	| = 100 ft

-------
Group #:	
FINAL GROUNDWATER PROBLEM: BETTENDORF, IOWA
Each group of students will determine, identify, draw, and calculate the items below and include them
in brief class presentation. Group scores (out of 100%) are based upon completion of each category
below.
SCORE:
	 1. Determine groundwater flow direction by constructing a groundwater surface
contour map and a flow net (not a 3-point problem) on the site map provided.
	 2. Identify the source(s) that contributed to the Leavings' groundwater problem.
	 3. Sketch a contaminant plume map from your collected subsurface date on the site
map sheet provided.
	 4. Draw a geologic cross section that lies perpendicular to the direction of the
groundwater flow; identify geologic units and groundwater level on the graph paper
provided.
	 5. Using your groundwater surface contour map, calculate the hydraulic gradient fD
in feet per foot between the source and the Leavings' residence.
	 6. Plot your slug test data on the semi-log sheet provided. Label your axes.
	 7. Calculate the hydraulic conductivity (K) value in feet per day using the Hvorslev
Method and the slug test data provided. Show calculations on the graph paper.
	 8. Calculate the seepage velocity (v) in feet per day using vs = KL/ne with an effective
porosity (nj value of 0.05.
	 9. Calculate an approximate transport time in years of the contaminant from the
source to the Leavings' residence using the equation: vsT (time in years) = D
(distance in feet).
	 10. Determine your final cost for conducting this hydrogeologic investigation:
$	.
	 TOTAL GROUP SCORE: (To be filled in by Course Director.)
Print group member names below:
a.
e.
b.
f.
c.
g-
a
h.
43

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LEAVINGS' RESIDENCE SITE, IOWA
SLUG TEST RESULTS
MW-6, Grid Location at E-12
ELAPSED
TIME
(minutes)
DEPTH TO
WATER
(feet)
CHANGE IN
WATER LEVEL
h (feet)
h/h.
static level
2.00
—
—
0.12
2.09
19.91
1.00
0.24
2.51
19.49
0.96
0.36
2.76
19.24
0.93
0.72
3.23
18.77
0.88
1.25
3.61
18.39
0.84
1,50
3.95
18.05
0.80
1,75
4.39
17.61
0.76
2.01
4.72
17.28
0.72
2,75
5.07
16.93
0.68
3.25
5.32
16.68
0.66
4.25
6.06
15.94
0.58
6.14
7.24
14.76
0.45
7.83
8.12
13.88
0.36
9.51
8.76
13.24
0.29
11.24
9.35
12.65
0.23
K =
r = 1 inch
L = 8.7 feet
R = 2.25 inches
r2 [n (L/'R)
2 LT
Lithology:
Fill = 2'
Loess = 13'
Till = 10'
Surface elevation = 680'
Chemistry = free product
GW elevation = 607"
44

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Glossary and Acronyms
acre-foot
adsorption
enough water to cover 1 acre to a depth of 1 foot; equal to
43,560 cubic feet or 325,851 gallons
the attraction and adhesion of a layer of ions from an aqueous
solution to the solid mineral surfaces with which it is in contact
advection
alluvium
anisotropic
aquifer
aquifer test
the process by which solutes is transported by the bulk motion
of the flowing groundwater
a general term for clay, silt, sand, gravel, or similar
unconsolidated material deposited during comparatively
recent geologic time by a stream or other body of running
water as sorted or semisorted sediment in the bed of the
stream or on its floodplain or delta, or as a cone or fan at the
base of a mountain slope
hydraulic conductivity ("K"), differing with direction
a geologic formation, group of formations, or a part of a
formation that contains sufficient permeable material to yield
significant quantities of groundwater to wells and springs. Use
of the term should be restricted to classifying water bodies in
accordance with stratigraphy or rock types. In describing
hydraulic characteristics such as transmissivity and storage
coefficient, be careful to refer those parameters to the
saturated part of the aquifer only.
a test involving the withdrawal of measured quantities of water
from, or the addition of water to, a well (or wells) and the
measurement of resulting changes in head (water level) in the
aquifer both during and after the period of discharge or
addition
aquitard
artesian
a saturated, but poorly permeable bed, formation, or group of
formations that does not yield water freely to a well or spring
confined; under pressure sufficient to raise the water level in a
well above the top of the aquifer
artesian aquifer
artificial recharge
see confined aquifer
recharge at a rate greater than natural, resulting from
deliberate or incidental actions of man
Introduction to Groundwater Investigations
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BTEX
benzene, toluene, ethylbenzene, and xylenes
capillary zone
negative pressure zone just above the water table where
water is drawn up from saturated zone into matrix pores due
to cohesion of water molecules and adhesion of these
molecules to matrix particles. Zone thickness may be several
inches to several feet depending on porosity and pore size.
capture
the decrease in water discharge naturally from a ground-water
reservoir plus any increase in water recharged to the reservoir
resulting from pumping
coefficient of storage
the volume of water an aquifer releases from or takes into
storage per unit surface area of the aquifer per unit change in
head
cone of depression
depression of heads surrounding a well caused by withdrawal
of water (larger cone for confined aquifer than for unconfined)
confined aquifer
geological formation capable of storing and transmitting water
in usable quantities overlain by a less permeable or
impermeable formation (confining layer) placing the aquifer
under pressure
confining bed
a body of "impermeable" material stratigraphically adjacent to
one or more aquifers
diffusion
the process whereby particles of liquids, gases, or solids
intermingle as a result of their spontaneous movement caused
by thermal agitation
discharge velocity
an apparent velocity, calculated from Darcy's law, which
represents the flow rate at which water would move through
the aquifer if it were an open conduit (also called specific
discharge)
discharge area
an area in which subsurface water, including both
groundwater and water in the unsaturated zone, is discharged
to the land surface, to surface water, or to the atmosphere
dispersion
the spreading and mixing of chemical constituents in
groundwater caused by diffusion and by mixing due to
microscopic variations in velocities within and between pores
Introduction to Groundwater Investigations
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DNAPL
dense, non-aqueous phase liquid
drawdown
effective porosity
evapotranspiration
flow line
gaining stream
gpm
groundwater reservoir
groundwater divide
groundwater system
groundwater model
groundwater
head
heterogeneous
homogeneous
the vertical distance through which the water level in a well is
lowered by pumping from the well or nearby well
the amount of interconnected pore space through which fluids
can pass, expressed as a percent of bulk volume. Part of the
total porosity will be occupied by static fluid being held to the
mineral surface by surface tension, so effective porosity will be
less than total porosity.
the combined loss of water from direct evaporation and
through the use of water by vegetation (transpiration)
the path that a particle of water follows in its movement
through saturated, permeable materials
a steam or reach of a stream whose flow is being increased by
inflow of groundwater (also called an effluent stream)
gallons per minute
all rocks in the zone of saturation (see also aquifer)
a ridge in the water table or other potentiometric surface from
which groundwater moves away in both directions normal to
the ridge line
a groundwater reservoir and its contained water; includes
hydraulic and geochemical features
simulated representation of a groundwater system to aid
definition of behavior and decision-making
water in the zone of saturation
combination of elevation above datum and pressure energy
imparted to a column of water (velocity energy is ignored
because of low velocities of groundwater). Measured in length
units (i.e., feet or meters).
geological characteristics varying aerially or vertically in a
given system
geology of the aquifer is consistent; not changing with
direction or depth
Introduction to Groundwater Investigations
47

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hydraulic conductivity volume flow through a unit cross-section area per unit decline
in head
hydraulic gradient	change of head values over a distance
Hi - H?
L
where:
H = head
L = distance between head measurement points
the study of interactions of geologic materials and processes
with water, especially groundwater
graph that shows some property of groundwater or surface
water as a function of time
hydrogeology
hydrograph
impermeable
infiltration
interface
intrinsic permeability
isotropic
K
laminar flow
LNAPL
losing stream
having a texture that does not permit water to move through it
perceptibly under the head difference that commonly occurs in
nature
the flow of movement of water through the land surface into
the ground
in hydrology, the contact zone between two different fluids
pertaining to the relative ease with which a porous medium
can transmit a liquid under a hydrostatic or potential gradient.
It is a property of the porous medium and is independent of
the nature of the liquid or the potential field.
hydraulic conductivity ("K") is the same regardless of direction
hydraulic conductivity (measured in velocity units and
dependent on formation characteristics and fluid
characteristics)
low velocity flow with no mixing (i.e., no turbulence)
light, non-aqueous phase liquid
a stream or reach of a stream that is losing water to the
subsurface (also called an influent stream)
Introduction to Groundwater Investigations
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mining
MSL
in reference to groundwater, withdrawals in excess of natural
replenishment and capture. Commonly applied to heavily
pumped areas in semiarid and arid regions, where opportunity
for natural replenishment and capture is small. The term is
hydrologic and excludes any connotation of unsatisfactory
water-management practice
mean sea level
non-steady state
steady state
optimum yield
overdraft
perched aquifer
permeability
permeameter
piezometer
(also called non-steady shape or unsteady shape) the
condition when non-steady shape the rate of flow through the
aquifer is changing and water levels are declining. It exists
during the early stage of withdrawal when the water level
throughout the cone of depression is declining and the shape
of the cone is changing at a relatively rapid rate.
(also called steady shape) is the condition that exists during
the intermediate stage of withdrawals when the water level is
still declining but the shape of the central part of the cone is
essentially constant
the best use of groundwater that can be made under the
circumstances; a use dependent not only on hydrologic factors
but also on legal, social, and economic factors
withdrawals of groundwater at rates perceived to be excessive
and, therefore, an unsatisfactory water-management practice
(see also mining)
a zone of saturation in a formation that is discontinuous from
the water table and the unsaturated zones surrounding this
formation. Some regulatory agencies include an upper limit
on the hydraulic conductivity of the perched aquifer
the property of the aquifer allowing for transmission of fluid
through pores (i.e., connection of pores)
a laboratory device used to measure the intrinsic permeability
and hydraulic conductivity of a soil or rock sample
a non-pumping well, generally of small diameter, that is used
to measure the elevation of the water table or potentiometric
surface. A piezometer generally has a short well screen
through which water can enter.
Introduction to Groundwater Investigations
49

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porosity
the ratio of the volume of the interstices or voids in a rock or
soil to the total volume
potentiometric surface
recharge
recharge area
safe yield
saturated zone
slug-test
specific yield
specific capacity
steady-state
storage coefficient "S"
storage
imaginary saturated surface (potential head of confined
aquifer); a surface that represents the static head; the levels to
which water will rise in tightly cased wells
the processes of addition of water to the zone of saturation
an area in which water that enters the subsurface eventually
reaches the zone of saturation
magnitude of yield that can be relied upon over a long period
of time (similar to sustained yield)
zone in which all voids are filled with water (the water table is
the proper limit)
an aquifer test made by either pouring a small instantaneous
charge of water into a well or by withdrawing a slug of water
from the well (when a slug of water is removed from the well, it
is also called a bail-down test)
ratio of volume of water released under gravity to total volume
of saturated rock
the rate of discharge from a well divided by the drawdown in it.
The rate varies slowly with the duration of pumping, which
should be stated when known.
the condition when the rate of flow is steady and water levels
have ceased to decline. It exists in the final stage of
withdrawals when neither the water level nor the shape of the
cone is changing.
volume of water taken into or released from aquifer storage
per unit surface area per unit change in head (dimensionless)
(for confined, S = 0.0001 to 0.001; for unconfined, equal to
porosity)
in groundwater hydrology, refers to 1) water naturally detained
in a groundwater reservoir, 2) artificial impoundment of water
in groundwater reservoirs, and 3) the water so impounded
Introduction to Groundwater Investigations
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storativity
sustained yield
the volume of water an aquifer releases from or takes into
storage per unit surface area of the aquifer per unit change in
head (also called coefficient of storage)
continuous long-term groundwater production without
progressive storage depletion (see also safe yield)
transmissivity
the rate at which water is transmitted through a unit width of
an aquifer under a unit hydraulic gradient
unsaturated zone
(vadose zone)
the zone containing water under pressure less than that of the
atmosphere, including soil water, intermediate unsaturated
(vadose) water, and capillary water. Some references include
the capillary water in the saturated zone. This upper limit of
this zone is the land surface and the lower limit is the surface
of the zone of saturation (i.e., the water table).
water table	surface of saturated zone area at atmospheric pressure; that
surface in an unconfined water body at which the pressure is
atmospheric. Defined by the levels at which water stands in
wells that penetrate the water body just far enough to hold
standing water.
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Intentionally Blank Page
52

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Selected
hydrogeology slides
and equations
Stream Flow

Q = Av
POROSITY
(NJ
The volumetric ratio between the void
spaces (Vv) and total rock (Vt):
Nt = V^ ; Nt = Sy + Sr
^ Sy = specific yield
Sr = specific retention
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Porosity
TOTAL POROSITY
(Nt):
EFFECTIVE POROSITY (Ne):
CLAY 40-85%
1-10%
SAND 25-50%
10-30%
GRAVEL 25-45%
15-30%
Total Head
m
Combination of elevation (z) and pressure
head (hp)
ht = z + hp
Total head is the energy imparted to a
column of water
' GROUNDWATER LEVEL
POINT OF
MEASUREMENT
/
t t
PRESSURE
HEAD
ELEVATION
HEAD
I
(hp)
HYDRAULIC
OR	(ht)
TOTAL
HEAD
T
' DATUM
(usually sea level)
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Uneonfined Aquifer
, I WATER |
Confined Aquifer
r
V




VADOSE y

aHPiW
1

SURFACE
CON
FININ
G UNTT^ftQUnARI
VADOSE
ZONE
RECHARGE
CONFINING LAYERS
(AQUITARDS)
55

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Artesian Groundwater System
RECHARGE AREA	RECHARGE AREA
POTENTIOMETRIC SURFACE
Artesian Groundwater System
FLOWING
ARTESIAN
WELL
OVERBURDEN
PRESSURE
HYDRAULIC
1* :v
I
i
Darcy's law
Q = KIA
•	Q = discharge
•	K = hydraulic
conductivity
•	I = hydraulic gradient
•	A = area

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Dairy's Law
•	The flow rate through a porous material is
proportional to the head loss and inversely
proportional to the length of the flow path
•	Valid for laminar flow
•	Assume homogeneous and isotropic
conditions
Hydraulic Conductivity
(K)
The volume of flow through a unit
cross section of an aquifer per unit
decline of head.

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Hydraulic Conductivity
Q= KIA
K= —
IA
ft .
t*> • Q
I = hydraulic gradient
^ • K = hydraulic conductivity
A = cross-sectional area
• Q = rate of flow
(Flow rate}
area
(length of
flow path)
Darcy's Law
Decreasing the
hydraulic head
decreases the
flow rate.
Qi > Q2

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Increasing the
flow path length
decreases the
flow rate.
Groundwater Velocity
•	Darcy's Law Q=KIAor -Q—= Kl
A
•	Velocity equation Q = Av or-^- = v
By combining, obtain:
•	v = KI Darcian velocity
Groundwater Velocity
• Because water moves only through pore
spaces that are connected, porosity is a factor.
Nt=-^orNt = Sr + Sy
ne = Sy = Nt - Sr ~ effective porosity
vs = seepage velocity
ne
59

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Transmissivity
• The capacity of the entire thickness of an
aquifer to transmit water
T= Kb
T = transmissivity
K = hydraulic conductivity
b = aquifer thickness
b = 100m
AQUITARD
I AQUITARD
Transmissivity
T= Kb
T = (20 m/d) (100 m)
T = 2000 m2 /d

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Storativity
•	The amount of water available for "use" in
an aquifer (storage coefficient)
•	"Specific yield" in an unconfined aquifer
Selected aquifer
stress test slides
Cooper - Jacobs Method
• Advantages
-	Less time to perform test; consider
straight-line drawdown over one log
cycle on the semi log graphical plot
-	Only one well required
-	Tests larger aquifer volume than slug
test
61

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Cooper - Jacobs Method
• Disadvantages
-	Requires conductivities >10~2 cm/s
-	Tests smaller portion of the aquifer
volume than multiple-well tests
-	Must handle discharge water
Cooper - Jacob Semi Log Plot
|	^-Log Lycle-^	|
D
r
a
w
d
o
w
n
Time
Cooper - Jacob Formulas
35 Q	T
T=— K= —
T = transmissivity feet squared per day (ft /da
Q = pump rate (gpm)
As= change in drawdown (ft/log cycle)
K = hydraulic conductivity ft/day
b = aquifer thickness (feet)
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Slug Tests
•	Perform on low-yielding aquifers (between
10"7 to 10"2 cm/s)
•	Water level is abruptly raised or lowered using
a slug or volume of water
•	Water level changes are recorded, and a ratio
of these changes (h) to the initial change in
head (h0) measurement is calculated and
plotted against the time when these changes
occurred
Slog Tests
•	The graph allows one to determine the
"hydrostatic time lag" (T0), i.e., the amount of
time necessary to obtain pressure equalization
between the measuring device and the
aquifer
•	This time lag accounts for some of the error
encountered in performing this type of test
DETERMlNATi
Slug
Tests
63

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Slug Tests
ADVANTAGES
•Can use small-diameter well
•No pumping = no discharge
•Inexpensive = less equipment required
•Estimate made in situ
•Interpretation/reporting time is shortened
Slug Tests
• Disadvantages
-	Very small volume of aquifer tested
-	Only apply to low conductivities
-	Transmissivity and conductivity only
estimates
-	Not applicable to large-diameter wells
-	Large errors if well not properly
developed
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