Characterizing Groundwater Flow Velocity And Preferential Flow Zones

GROUND WATER SAMPLING • WATER LEVEL & PRESSURE • WATER SAMPLE FILTRATION • GROUND WATER REMEDIATION • GEOPHYSICAL MEASUREMENTS

The Nielsen Environmental Field School, Inc.
2012 North American Environmental Field Conference & Exposition (East)

CHARACTERIZING GROUND-WATER
FLOW VELOCITY AND PREFERENTIAL
FLOW ZONES
2650 East 40th Avenue • Denver, Colorado 80205 • www.geotechenv.com


Agenda
• Introductions



Jeff Popiel
President and CEO

JeffP@GeotechEnv.com
303.320.4764



Geotech Corporate Headquarters
Denver, Colorado USA

…a world leader in environmental technology,
manufacturing and product training since 1978.
www.GeotechEnv.com


an environmental industry
products leader since 1978

partners with federal, state,
local and international
government agencies

over 20,000 private sector
clients worldwide

distribution in 72 countries

provides products and product
training to colleges, universities
and technical schools around the globe



Audience Introductions
• Name
• Company name
• Experience with site characterization



Why Characterize Groundwater Flow
• Plan efficient remediation
– Quantify extent and magnitude of underlying
contaminants
– Define exposure routes
– Define flow velocity
– Identify and assess risks



Criteria for Characterizing
Groundwater Flow
• Site geology
– Distribution of geologic materials
– Stratigraphic and structural relationships
– Features that affect the subsurface migration of contaminants
• Rate and direction of ground water flow
– All impacted aquifers
• Groundwater
– Contaminants present
– Concentrations of contaminants
– Vertical and lateral extent of contaminants



Methods of Groundwater Flow
Characterization
• Groundwater level measurements
• Potentiometric maps
• Well clusters screened at different depths
• Seasonal and temporal factors
• Hydraulic conductivity
• Tracer tests



How Does the Borescope Work?
• Directly observes groundwater flow velocity
• Measures flow at selected depths within a well
and thus the ability to measure flow from
individual fractures
• Allows capture of an aerial and vertical
distribution of groundwater flow velocities that is
useful for the interpretation of contaminant
migration in complex flow systems



Why is a Borescope Better?
• Hydraulic conductivity values calculated from most aquifer
tests in fractured rocks are meaningless
• Groundwater flow directions in fracture porous media can
be diagonal to the hydraulic gradient
• Groundwater flow and contaminant transport in fractured
porous aquifers is complicated by flow in porous blocks
• Flow in sandstone or siltstone blocks may be in the
direction of the hydraulic gradient while groundwater in
the fractures will migrate in a direction parallel to the
fractures



Conceptual Diagram

Source: Oak Ridge National Laboratory, “Characterization of a Fractured Aquifer Using the Colloidal Borescope”


AquaLITE 7.2x



AquaLITE 7.2x
Software Outputs



Computer
High-Resolution Video digitizer
Monitor

Reservoir/Sand
Membrane Screen Electronic cable

5-cm Fully 10-cm Fully
Penetrating Well Penetrating Well

Influent
Water Level

Sand
Pack
132 cm

Effluent
Water Level
Groundwater
Flow

Sand Colloidal
Pack Borescope

92 cm

9 cm Manometer
MSC047
153 cm

Courtesy: ORNL



EXPERIMENT #1
Well Diameter Comparison
5-cm Fully 10-cm Fully
Penetrating Well Penetrating Well Screen

Sand #1

Groundwater Flow

EXPERIMENT #2
Sand Pack Influence
Coarse-Grain
No Sand Pack Sand Pack Screen

Sand #2

Groundwater Flow

EXPERIMENT #3
Fully vs Partially Penetrating Well
Fully Partially
Penetrating Well Penetrating Well
Screen

Sand #3

Groundwater Flow

EXPERIMENT #4
Layered Flow
5-cm Fully Coarse-Grain
Penetrating Well Sand Pack
Screen

Sand #3

Sand #4

Sand #3
Groundwater Flow
Sand #5 Courtesy: ORNL



Laboratory tracer test results using sodium chloride
with an average linear porewater velocity in the
sand equal to 0.10 m/d. (Sudicky et al., 1985)

Flushing Ports

Silt Nylon Mesh
Screen
Sand Flow Direction 0.2m

Silt Nylon Mesh

Flushing Ports

1.0m

100
Measured
Thick-layer Solution, Dq = 0
Relative Concentration, c/c0

0.80 Thin-layer Solution, Dq = 0
Thin-layer Solution, Dq = 0
No Diffusive Loss
0.60

0.40

0.20

0.00
0 4 8 12 16 20 24 28 32 36

Courtesy: ORNL
Time, days
MSC115



a) b)
50 50

60 60
Fine (#4) Fine (#4)
70 70

Medium (#3)

Depth (cm)

Depth (cm)
80 80

90 90

100 100 Medium (#3)
110 110
Coarse (#5)
Coarse (#5)
120 120
100 60 20 20 60 100 0.01 0.1 1.0
80 40 40 80
Degree from expected Velocity in well (cm/s)
flow direction

c) d)
50 50

60 60 Fine (#4)
Fine (#4)
70 70
Depth (cm)

Depth (cm)
80 80
Medium (#3)
90 90
Medium (#3)
100 100

110 110
Coarse (#5)
Coarse (#5)
120 120
100 60 20 20 60 100 0.01 0.1 1.0
80 40 40 80
Degree from expected Velocity in well (cm/s)
Courtesy: ORNL
flow direction



a b
Filter Pack

ri Well Bore
r
Well Bore
i

Groundwater Flow

c d
Filter Pack Finite Skin or
Filter Pack Development Zone

3 K1 K2 K3
2 1
Well Bore Well Bore

r r1
1
r2
r2
r3
r3

MSC102
Courtesy: ORNL



Development of fresh water zone within the
screened interval of sampling well
(Bromide tests) After Robin and Gillham (1987)

Well
1.0
6

0.5
#5 Point #5

0
5

Concentration (measured/injected)
1.0

0.5
Distance From Bottom Of Well (m) Point #4
4
0

#4 1.0

0.5
3 Point #3
Relative Br

0

1.0

2
0.5
Point #2
#3

0

1.0
1
Screen #2

0.5
Point #1

0 #1 0

0 20 40 60 80 100 120 140

Time (hr)
MSC028



FEET
0 200 400 600
0 50 100 150
METERS



Courtesy: ORNL



Preferential Flow
• Preferential flow



R
O
U
T
E
1

D
840

A
811

O
M70

R
882

W
841

O
L
R

L
O
R

O
U
A
O

843

H
T
U

E
B
T

2
E
3

A L
R R
N

C O
W7B N
W-25N-18
N

B

A 879
818
N
871
N 883
876
C
875 W-7
873
891B 870 877
N
W-18 891A W- 2 5 N- 1 3
W -20
880

W8 7 3- 0 6
W8 72 - 02

A D W- 25 N - 1 1
R O

W
O
L L
O
H

MSC116

N
BORESCOPE TEST SITE

25% 50% FEET
0 100 200 3 0 0 4 00 50 0
Colloidal Borescope Well
0 3 0 6 0 9 0 120 150
879
Building METERS

Road
Direction and Magnitude
of Groundwater Flow Stream



90

120

150

180

210

240

270

300



X

X

X

X

X

X



X X X X X X X X X X X X X X X X X X X

X X X
X X

X

X

X
X
X

X

X
X
X

X
X X

X
X X X

X
X

X
X
X

X
X

X
X X
X X

X
X
X

X

X
X

FEET
0 100 200 300 400 500

0 30 6 0 90 120 150
METERS



X
X X

X
X

X

X
X

X

X

X

FEET
0 100 2 00 3 0 0 40 0 5 0 0

0 3 0 6 0 9 0 120 150
METERS



Tidal Influence on Groundwater Flow



Groundwater
Flow in a Perched
Aquifer



Summary


Characterizing Groundwater Flow Velocity And Preferential Flow Zones

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