In Situ Thermal Hydrolysis of
1,2-Dichloroethane (EDC) in
Fine-Grained Soil: Pilot Test
October 2014
Michael Singer/KNV
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1
Acknowledgements
• Joanne West/Dow
• Audrey Sidebottom/Dow
• Jason Cole/CH2M HILL
• Jake Eimers/CH2M HILL
• Phil Smith/CH2M HILL
• John Mason/CH2M HILL
• Gary Hickman/CH2M HILL
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2
Agenda
• Site Background
• Hydrolysis of EDC
• Pilot Study Approach
• Heating History and Issues
• Sampling Results
• Summary and Conclusions
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3
Site Background
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4
Why the need for the project
• Elevated EDC in soil and
groundwater due to historical
operations (former EDC product
rail loading facilities)
• Limited Access – cannot disrupt
operational rail lines
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Page 5
Site Geology
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6
Extent of Contamination
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Page 7
Hydrolysis of 1,2-dichloroethane
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8
EDC Transformation
• Neutral Hydrolysis – reaction with water at neutral pH
conditions
• EDC Hydrolysis
•
•
•
•
C2H4Cl2 (EDC) + 2H2O → C2H6O2 (ethylene glycol) + 2H+ + 2ClAbiotic production of ethylene glycol
Ethylene glycol is biodegradable
Temperature strongly accelerates hydrolysis rate
+ H2O
EDC
Ethylene Glycol
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9
Thermal Hydrolysis Lab Test
• 2008 Lab Study:
• Site soil/groundwater
• Closed batch reactors
incubated at approx.:
EDC Mass Degradation Based on Degradation Products
• 20°C
• 80°C
• 100°C
• Monitored for EDC and
abiotic degradation
products (Cl-, glycol)
Thermal hydrolysis laboratory study conducted at CH2M
HILL’s Applied Sciences Laboratory in Corvallis, Oregon to
evaluate abiotic degradation of EDC in soil taken from site.
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10
Field Scale Pilot Test
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11
Field-scale Pilot Study
Pilot Objectives:
1. To reduce the concentration of EDC in soil at Block
270 Former Railcar Loading Area.
2. Develop a better understanding of the effectiveness
and applicability of in situ thermal hydrolysis as a
remedial technology for EDC
3. Provide operational data to help optimize the design
and operation of future in situ thermal hydrolysis at
other sites.
4. Target Concentrations: 500 mg/kg in soil
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Electrical Resistance Heating





Alternating current is applied
to subsurface electrode arrays
Electrical resistance of the soil
generates heat
ERH relies on water for
electrical conductance
SVE for contaminant recovery
when needed
Temperature limited to boiling
point of water at local pressure
Typical energy applied – 200 to 300 kW-hrs/cy
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Site Layout
• 24 vertical electrodes
• 15 Monitoring Locations
(Temperature, Water Samples)
• Initial target temp.: 60°C
• Depth: 2-7 m interval
• Target area: ~16m x 27m
• Treatment Soil Volume: 2,160
m3
Water
Tank
Power
Distribution
Panel
Heat
Water Control System
Trace
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Panel
Page 14
Site Photos
Site
Preparation
Electrode
Connections
Site
Looking
Southwest
Monitoring
Well
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Page 15
Heating History and Issues
16
Average Subsurface Temperature
100
Unexpected
Observations:
Electrodes dried/multiple
tap changes and
modifications
90
Multiple daily shutdowns
Multiple tap changes
80
70
Average Temperature, Celsius
• Rapid response to
system changes
• Area near center of
site difficult to heat
60
Water shutoff due to leak
50
Dec.16 System Shutdown
40
30
20
24 hour shutdown
10
0
24 hour shutdown
Mar.12 System Startup
Date
17
Soil Temperatures Varied in Pilot
Test Area
• Differences in soil properties
(EC)?
• Unknown source of water in
area?
18
Sampling Results
19
Sample Locations
Groundwater
20
Groundwater Results - Summary
Location Name
12MW0005-270
12MW0008-270
12MW0009-270
12MW0011-270
12MW0012-270
Sample
Date
EDC
(mg/L)
11-Mar-13
2510
34.1
31-May-14
19.3
127
11-Mar-13
71.9
96.2
31-May-14
56.3
158
28-Aug-13
1540
298
31-May-14
10.5
62.5
11-Mar-13
2590
26.8
31-May-14
0.0958
10.5
28-Aug-13
153
108
31-May-14
23
192
Chloride
(Cl) (mg/L) % Reduction ([O-E]/E)
-99%
-22%
-99%
-100%
-85%
21
EDC vs.
Chloride
MW05
Chloride
3000
250
2500
200
2000
150
1500
100
1000
50
500
0
1/26/13
5/6/13
8/14/13
MW08
2500
2000
150
1500
100
1000
50
500
8/14/13
11/22/13
3/2/14
6/10/14
0
9/18/14
EDC (mg/L)
200
Chloride (mg/L)
EDC (mg/L)
EDC
250
5/6/13
3/2/14
6/10/14
0
9/18/14
MW11
Chloride
3000
0
1/26/13
11/22/13
Chloride
3000
250
2500
200
2000
150
1500
100
1000
50
500
0
1/26/13
Chloride (mg/L)
EDC
Chloride (mg/L)
EDC (mg/L)
EDC
5/6/13
8/14/13
11/22/13
3/2/14
6/10/14
0
9/18/14
22
EDC Vs.
Temperature
3000
EDC (mg/L)
2500
2000
1500
1000
500
0
1/6/13
3/7/13
5/6/13
7/5/13
EDC
1000
500
0
1/6/13
3/7/13
5/6/13
7/5/13
EDC
9/3/13 11/2/13 1/1/14
Temperature
2500
2000
1500
1000
500
0
1/6/13
3/7/13
5/6/13
7/5/13
EDC
9/3/13 11/2/13 1/1/14
100
90
80
70
60
50
40
30
20
10
3/2/14
Temperature Deg C
1500
3000
EDC (mg/L)
2000
100
90
80
70
60
50
40
30
20
10
3/2/14
Temperature Deg C
EDC (mg/L)
2500
Temperature
MW011
MW08
3000
9/3/13 11/2/13 1/1/14
100
90
80
70
60
50
40
30
20
10
3/2/14
Temperature Deg C
MW05
Temperature
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Soil Results
4500
4000
600
EDC in Soil
500
3500
3000
400
EG, mg/Kg
EDC, mg/Kg
Ethylene Glycol in Soil
2500
2000
1500
300
200
1000
100
500
0
BH07
Pre-Test
BH08
Oct-13
BH09
Dec-13
BH10
0
BH07
BH08
Oct-13
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BH09
BH10
Dec-13
24
Summary and Conclusions
25
Summary and Conclusions
• EDC Reduced in soil and groundwater (pilot test objectives met)
• Indications that hydrolysis occurred
• Some reductions may be result of other factors (volatilization?)
• Uneven soil heating was a problem
• Final soil and groundwater sampling underway this week
• Wells are being slug tested to evaluated differences in hydraulic K
across the site
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Factors affecting choice of in situ hydrolysis
• Only appropriate for chemicals that hydrolyze at relatively low
temperatures (for example, EDC, 1,1,1-TCA)
• Site hydrogeology (low groundwater flow velocities helpful in
achieving target temperatures)
• Site factors, such as access restrictions or presence of structures, that
might preclude other approaches, such as soil mixing
• Availability and cost of energy
• Local infrastructure, especially occupied buildings
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EDC, Chloride, and Ethylene Glycol
MW009
3000
90
80
70
60
2000
50
40
1500
30
1000
20
Ethylene Glycol, mg/L
EDC and Chloride, mg/L
2500
10
500
0
0
07/05/13
09/03/13
11/02/13
EDC
01/01/14
Chloride
03/02/14
Ethylene Glycol
05/01/14
-10
06/30/14
28