UCRL-PRES-XXXXXX
This work was performed under the auspices of the U.S. Department of Energy by the University of California,Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.
This work was performed under the auspices of the U.S. Department of Energy by the University of California,Lawrence Livermore National Laboratory under contract No. W-7405-Eng-48.
A Stable Isotope Tracer Experiment Using Hetch-Hetchy Water
A Stable Isotope Tracer Experiment Using Hetch-Hetchy Water
Madrid1, V.M., Gregory1, S., Verce1, M.F., Radyk1, J., Singleton2, M, Eaton2, G., Esser2 B. K. 1Environmental Restoration Division, 2Chemical Sciences Division
Lawrence Livermore National Laboratory
UCRL-PRES-228848
Madrid1, V.M., Gregory1, S., Verce1, M.F., Radyk1, J., Singleton2, M, Eaton2, G., Esser2 B. K. 1Environmental Restoration Division, 2Chemical Sciences Division
Lawrence Livermore National Laboratory
UCRL-PRES-228848
D = -104‰ 18O = -14.0‰
D = - 44‰18O= - 3.4‰
Talk Outline
• Site Background
• Objectives
• Experiment Design
• Data
• Results
• Conclusions
Site 300 location map
T2 test area
Isotope studies at Site 300
3H
235U/238U
18O,D(H2O)
15N,18O(NO3)
Typical Site 300 Contaminant Source area
• 15 m x 15 m (50 ft x 50 ft)
• High contaminant concentrations
• Low Permeability
• Limited Recharge
Therefore, conventional pump & treat has limited effectiveness.
Site Air Photo VOC plume
T2 tracerexperiment
Overall Objective Evaluate feasibility of reagent injection as a source area cleanup technology using an existing well field.
Phase 1: Tracer Test
Emphasize
Performance
Monitoring
Emphasize
CleanupPhase 3: Multi-well, source area cleanup
Phase 2: Reagent injection
Injection rate
Area-of-influence
Tracer / ground water mixing
• Single well, continuous injection tracer test.
• Constant head injection about 5 m (17 ft ) above the
static water table.
• Inject isotopically distinct, low salinity Hetch-Hetchy
(H-H) water until it is detected in observation wells.
Tracer Experiment Design
D = -104‰ 18O = -14.0‰
D = - 44‰18O= - 3.4‰
Why Hetch-Hetchy Water? • Conservative tracer
• Large salinity & isotopic contrast compared to site
ground water
• Non–toxic
• Analysis is commercially available & inexpensive
Performance Monitoring
• Water levels: hourly
• Stable Isotopes:
18O weekly
D every 6 weeks
• Specific Conductance: weekly
• VOCs: monthly
T2 site map
[920.3]
[919.4]
[921.6]
[918.6]
[916.8]
[918.3]
922
920
918
Pre-injectionground water
elevation contour
Ground water flow
direction
dry
dry
Cross section A – A'
K = 10-4 - 10-6 cm/sec
K = < 10-6 cm/sec
Injectionwell
Outcrop of gravel / clay contact
Tps clay perching horizon
Calcium carbonate cemented gravel
Caliche-filled fractures
Friable, medium-grained sand
Tpsg gravel
1 meter
916
918
920
922
924
926
16-Nov-2004 15-Dec-2004 13-Jan-2005 11-Feb-2005 12-Mar-2005 10-Apr-2005 9-May-2005 7-Jun-2005
GW
E (
ft M
SL)
-T2A
-T2
-1825
-T2D
-T2B
-1833
START
STOP
RE-START
Pre-injection
Dual isotope sample
0
0.2
0.4
0.6
0.8
1
1.2
11/16/04
Daily
Rain
(in
ches)
dailyrain
Observation well hydrographs
18O time-series plot
18O
Start ofInjection
Dual isotope sample
Specific Conductance S
peci
fic C
ondu
ctan
ce (
µS
) Start ofInjection
Dual isotope sample
Pre-injection isotope signatures
Hetch-Hetchy Tracer
Ground water (pre-injection)S300 precipitation
(2006)
25%
50%
75%Tracer-g
round water mixing lin
e
D
18O
[(18Osample- 18Ogw)2+ (Dsample- Dgw )2]1/2
[(18OHH- 18Ogw)2+ (DHH- Dgw )2]1/2
= Tracer fraction
SMOW
Plot of all 18O & D data
Hetch-Hetchy Tracer
25%
50%
75%Tracer-g
round water mixing lin
e
D
18O
SMOW
Ground water (pre-injection)
Isotope plots for individual wells
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0
tracer-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0
18O
D
tracer1833
12
3
456
7
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0
-110
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0-15 -14 -13 -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0
18O
D
tracerT2
18O
D
T2A
18O
D
tracer 1825
12
4
5
67
1
3
4
56
7
12
34
5
6
32
7
1: Jan 132: Mar 13: Apr 154: May 235: Jul 216: Aug 187: Sep 13
Startinjection
Stopinjection
Low salinityarrives
High salinityarrives
Time-series plot of tracer fraction
Start ofInjection
End ofInjection
Change in salinityobserved at T2 & 1825
Time-series tracer distribution
Pre-injection Jan 21 May 23
July 21
-1824-T2-1825
-1833
-T2A-T2B
-T2D
-T2C
5
102550
75
510
2550
510
2550
75
Post-injection Sep 13
Ground water flow direction
Injectionwell
Extent ofsaturation
May 23
July 21 Post-injection Sep 13
20,0
00
10,0
00
1,00
0
100
20,000
20,000
10,0
00
1,00
0
20,000
10,0
00
1,00
0
-1824
-T2-1825
-1833
-T2A
-T2B
-T2D
-T2C
Pre-injection Jan 21
Time-series VOC distribution
Results
• Under a sustained, induced gradient of 0.3, an injection rate of about 100 L /day & a tracer velocity of 0.1 m/day was achieved.
• An immediate (< 1 hour) ground water level rise was observed in all wells at the onset of injection.
• In some wells that exhibited an immediate water level response, no tracer was detected during injection.
• Salinity decreased in the nearest observation well, while in other wells salinity increased or remained essentially the same.
• At the end of injection, the nearest observation well contained about 25% tracer. Other wells contained tracer concentrations ranging from 0 to 12 %.
Conclusions• H-H reservoir water is a good, conservative tracer when
injected into an aquifer with significantly different isotopic composition & salinity.
• Rigorous monitoring of multiple, independent data sets was the key to understanding how this source area responded under stress conditions.
• Under a steep induced gradient, the saturated zone responded like a confined system.
• Differences in salinity trends & tracer arrival times suggest the injected H-H water took separate pathways to the observation wells.
• Reagent injection is feasible at Site 300, however, some plume displacement is unavoidable.
AcknowledgementsAcknowledgements
• Brad Esser, Mike Singleton & Gail Eaton Brad Esser, Mike Singleton & Gail Eaton for mass spectrometry & data analysisfor mass spectrometry & data analysis
• Steve Gregory, Billy Clark, & Kian Atkinson Steve Gregory, Billy Clark, & Kian Atkinson for field instrumentation & data collectionfor field instrumentation & data collection
• Matthew Verce, Steve Gregory & John RadykMatthew Verce, Steve Gregory & John Radykfor data analysisfor data analysis