Dana Swift, Joe Rothermel, Bob Starr, Brennon Orr
North Wind, Inc., Idaho Falls, Idaho
Gordon Bures; Frac Rite Environmental Ltd., Calgary, AlbertaNovember 7, 2012
Remediation of a TCE Groundwater Plume using
Hydraulic Fracturing to Emplace ZVI/Carbon Amendment
Site History• Operational disposals of TCE‐contaminated wastewater (1960‐1965)• UST Closures (1994), Site Investigation (1996),
Remedial Investigation (1999), Feasibility Study (2003), Continued Site Characterization (2003‐2008), Pilot Test (2009), Interim Action (2011)
CSM Development and Refinement
Conceptual Site Model
Remedial Actions and Activities
Initial CSM DevelopmentOct 2008
Site CharacterizationOct‐Dec 2008
Pilot TestApr‐May 2009
CSM UpdateApr 2009
CSM UpdateDec 2010
Interim Action Planning
Jan‐May 2011
CSM UpdateJun 2011
Interim Action Jul‐Aug 2011
Create treatment pathways to increase:
• permeability • treatment area• contact with
contaminants
… and facilitate• emplacement or injection of treatment amendments.
Hydraulic fracturing provides an opportunity to remediate low permeability formations that would not otherwise be amenable to in situ treatment.
Hydraulic Fracturing for Remediation
FRAC RITE ENVIRONMENTAL LTD.YouTube: Frac Rite
Pilot Test Design• Hydraulic fracturing to emplace EHC‐G®• EHC‐G® is zero valent iron (ZVI) and complex carbon• Fracture mapping using tiltmeters
Fracture Boreholes7 source area2 distal plume
Pilot Test Amendment Distribution• Vertical coverage across entire saturated zone (every ~6 ft)• Amendment distribution radius ~65 to ~80 ft• Extensive, overlapping fracture network in source area
Performance MonitoringBiotic TCE Degradation• Carbon Amendment• Anaerobic Reductive Dechlorination(ARD) Pathways
Abiotic TCE Degradation• ZVI• Chemical DechlorinationPathways
TCE
cis-DCEvinyl chloride
chloroacetyleneacetylene
ethene+
chloride
short livedintermediates
TCE cis-DCE vinyl chloride ethene
chloride chloride chloride
Time
TCE
Con
cent
ratio
n cis-DCEVC
Time
Con
cent
ratio
n
intermediates persist in biotic pathway
Performance Monitoring
0
250
500
750
1000
1250
1500
1750
Oct‐08 Mar‐09 Sep‐09 Mar‐10 Sep‐10 Mar‐11
Concen
tration (ug/L)
VOCs at MW‐21
0
750
1500
2250
3000
3750
Oct‐08 Mar‐09 Sep‐09 Mar‐10 Sep‐10 Mar‐11
Concen
tration (ug/L)
VOCs at MW‐22
TCE cis‐DCE VC Ethene
0
100
200
300
400
500
Oct‐08 Mar‐09 Sep‐09 Mar‐10 Sep‐10 Mar‐11
Concen
tration (ug/L)
VOCs at MW‐22
0
100
200
300
400
500
Oct‐08 Mar‐09 Sep‐09 Mar‐10 Sep‐10 Mar‐11
Concen
tration (ug/L)
VOCs at MW‐21
TCE Pre-Pilot Test
TCE 21 Months Post-Pilot Test
Performance Monitoring
Pilot Test Lessons Learned#1 TCE mass reduction correlates with amendment distribution. • High TCE reductions (>90%) = extensive fracture network,
high amendment mass distributed• Moderate TCE reductions (~40‐80%) = increased distance from
fractures, lower amendment mass distributed
Aug 09 Correlationy = 0.0005x + 0.2096
R² = 0.8139
0%
20%
40%
60%
80%
100%
0 200 400 600 800 1000 1200 1400 1600 1800
% TC
E Re
duction
Amendment Mass (lbs)/Distance from Borehole (ft)
TCE Reduction and Amendment Distribution
Aug‐09 Nov‐09 Feb‐10
#2 The emplaced amendment resulted in significant TCE degradation.
Pilot Test Lessons Learned
0%
25%
50%
75%
100%
Apr‐09 Jul‐09 Nov‐09 Feb‐10 May‐10 Sep‐10 Dec‐10
% TCE
Mass R
emaining
Time after Pilot Test Implementation
Percent of TCE Mass Remaining Over Time
Source Area
On‐Site Plume
Whole Plume
#3 Plume configuration is not always a good indication of contaminant fate and transport.
Vicinity of Primary Contaminant Source Release Area
Approximate Location of Secondary Contaminant Source Release Area
Extent of 5 ug/L TCE Isopleth
Figure is not to scale
Interim Action Design
Projected injection radius of 60 to 80 ft
Pre-Interim ActionTCE Contours
• Design targeted the plume area with TCE concentrations >100 ug/L• Hydraulic fracturing to emplace EHC®; 6 distal plume boreholes• Vertical coverage across saturated zone (every 3 to 6 ft)
Performance MonitoringPre-Interim ActionTCE Concentrations
• Reduction to below the TCE MCL within 6 months where highest amendment distribution
• Minimal to no TCE reduction where amendment did not directly impact groundwater in vicinity of well
0
200
400
600
800
Oct‐08 Apr‐09 Nov‐09 May‐10 Dec‐10 Jun‐11 Jan‐12 Aug‐12
Concen
tration (ug/L)
VOCs at MW‐13
TCE cis‐DCE VC
Ethene Pilot Test Interim Action
0
100
200
300
400
500
Oct‐08 Apr‐09 Nov‐09 May‐10 Dec‐10 Jun‐11 Jan‐12 Aug‐12
Concen
tration (ug/L)
VOCs at MW‐9
Performance MonitoringPre-Interim ActionTCE Concentrations
• Continued TCE reduction 36 months post‐Pilot Test
• Slight TCE rebound but overall declining trends
0
100
200
300
400
500
600
700
Oct‐08 Apr‐09 Nov‐09 May‐10 Dec‐10 Jun‐11 Jan‐12 Aug‐12
Concen
tration (ug/L)
VOCs at MW‐22
TCE cis‐DCE VC Ethene
0
100
200
300
400
500
600
700
Oct‐08 Apr‐09 Nov‐09 May‐10 Dec‐10 Jul‐11 Jan‐12 Aug‐12
Concen
tration (ug/L)
VOCs at MW‐12
0
100
200
300
400
500
600
700
Oct‐08 Apr‐09 Nov‐09 May‐10 Dec‐10 Jun‐11 Jan‐12 Aug‐12
Concen
tration (ug/L)
VOCs at MW‐21
Conclusions
The use of hydraulic fracturing to emplace ZVI/carbon amendment resulted in effective groundwater remediation of TCE.
Traditional groundwater remediation technologies would be difficult to implement at this site.
Future Actions
• Site characterization activities prior to designing the full scale remedy:• Plume delineation• Investigate vertical contaminant
distribution• Aquifer testing
• Full‐scale design:• Hydraulic fracturing to treat
remainder of plume• Long term remedy monitoring
Acknowledgments
• This project is funded through the United States Army Corps of Engineers, Omaha District.
• Colorado Department of Public Health and Environment• Environmental Protection Agency Region 8
Corresponding Author:Dana SwiftNorth Wind 1425 Higham StreetIdaho Falls, ID [email protected](208) 557-7835