Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can...
-
Upload
dwayne-barton -
Category
Documents
-
view
217 -
download
2
Transcript of Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can...
![Page 1: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/1.jpg)
Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental
Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?
John R. Nimmo, Kim S. Perkins, and Kari A. Winfield
USGS, Menlo Park, California
Geological Society of AmericaDenver, Colorado
November 9, 2004
![Page 2: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/2.jpg)
Idaho
Eastern Snake River PlainINEEL
Subsurface DisposalArea (SDA)
![Page 3: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/3.jpg)
Subsurface Disposal Area
200 m toWater Table
Fractured BasaltInterbedded with Thin Layersof Coarse To Fine Sediments
![Page 4: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/4.jpg)
June 21-23, 1999:Apply tracer to spreading areas.
1999-2000:Sample available wellsin unsaturated zone and aquifer (symbols).
2 km
Diversion
SDA
![Page 5: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/5.jpg)
Chemical Tracer
• Previously applied in geothermal applications
• Conservative in subsurface materials
• Detectable to 0.2 ppb
![Page 6: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/6.jpg)
June 21-23, 1999: Applied 725 kg of tracer
![Page 7: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/7.jpg)
Sediment
Basalt Aquifer
Perched Water
Snake River Plain AquiferGround water mound
Subsurface Disposal AreaSpreading area
BasaltB-C Interbed
A-B Interbed
C-D Interbed
Prevailing ground water flow direction
Depth to aquiferapproximately200 meters
![Page 8: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/8.jpg)
1 km
SDA
B-C (34 m)
Detection
Non-detect
C-D (73 m)
Detection
Non-detect
Aquifer (200 m)
Detection
Non-detect
Sampling Results
![Page 9: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/9.jpg)
0
1
2
3
4
5
0 50 100 150 200 250
Days post tracer application
Co
nce
ntr
atio
n (p
pb
)
USGS 92
USGS 120
C-D and Aquifer Well Detections
Aquifer(200 m depth;0.2 km away)
CD Interbed(73 m depth;1.3 km away)
![Page 10: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/10.jpg)
Speed of Travel
• Vertical (at edge of SAB): 200 m
qvertical* = 3 10-2 cm/s
• Horizontal (SAA to SDA): 2.1 km
qhorizontal* = 4 10-2 cm/s
* Flux density for effective porosity of 0.3
(7 ± 2) days= 30 (± 10) m/day
(60 ± 30) days= 35 (± 17) m/day
![Page 11: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/11.jpg)
Numerical modeling by Richards’ Equation
(VS2DT code)
Water Content
X (m)
Z (
m)
Basalt Ksat= 1.7 cm/sPorosity= 0.33
SedimentKsat= 5.8 x 10-3 cm/s
104 days
![Page 12: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/12.jpg)
Model SensitivityParameter Initial Value Modified Value Sensitivity
Surficial Sediment Ksat (cm/s) 5.79 x 10-4 5.79 x 10-3 High
Combination of Surficial Sediment and Basalt Ksat (cm/s)
5.79 x 10-4
and0.17
5.79 x 10-3
and 1.7
High
Basalt Porosity .23 .33 Low
Basalt Residual Moisture Content 0 0.1 None
Surficial Sediment Van Genuchten 0.1216 0.2432 Low
Combination of Surficial Sediment and Basalt Van Genuchten
0.1216and
0.0384
0.242and
0.0768Low
Surficial Sediment Van Genuchten n 1.36 1.72 Low
Combination of Surficial Sediment and Basalt Van Genuchten n
1.36and
1.474
1.72and
1.948Low
Surficial Sediment Thickness (m): 2 Cases
0.52.0
and 0
High
Ponding Depth (m) 2.0 4.0 Low
![Page 13: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/13.jpg)
Driving Force in Fractured Basalt
Example: Spreading Area A to SDA on CD Interbed
Gradient: 9.4 m / 2100 m = 0.0045
Perched Water
Sloping Interbed
SAA
9.4 m
WellUSGS-92
2.1 km
Land Surface
![Page 14: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/14.jpg)
Horizontal Flow Along Sloping Interbeds
-6.00E-03
-5.00E-03
-4.00E-03
-3.00E-03
-2.00E-03
-1.00E-03
0.00E+001 1.1 1.2 1.3 1.4 1.5 1.6 1.7
Distance From Spreading Area (km)
Ave
rag
e G
rad
ien
t o
f In
terb
ed f
rom
Sp
read
ing
A
rea
to D
etec
tio
n P
oin
t
B-C Interbed, No Detection
B-C Interbed, Tracer Detected
C-D Interbed, No Detection
C-D Interbed, Tracer Detected
![Page 15: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/15.jpg)
Darcy’s law calculation
Example: Spreading Area A to SDA on CD Interbed
q = 4 10-2 cm/s, inferred from observation
Gradient = 0.0045, based on interbed elevation data
K 9 cm/s
![Page 16: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/16.jpg)
Estimated Maximum Effective Hydraulic Conductivity
Medium & Source Method Khoriz (cm/s)
1-cm Gravel
(Fayer and others, 1992)Lab measurement 0.35
INEEL UZ
(this study)Darcy calculation 9
INEEL UZ
(this study) RE numerical model > 1.7
INEEL UZ
(Wood & Norrell, 1996)Large-Scale Infiltration Test
of 1994 0.09
INEEL UZ (Magnuson & Sondrup, 1998) TETRAD calibration 0.009
INEEL Sat. Zone
(Anderson and others, 1999)Single-well aquifer tests 11
![Page 17: Unsaturated-Zone Case Study at the Idaho National Engineering and Environmental Laboratory: Can Darcian Hydraulic Properties Predict Contaminant Migration?](https://reader030.fdocuments.net/reader030/viewer/2022032805/56649eea5503460f94bfb8cd/html5/thumbnails/17.jpg)
Conclusions for Prediction of Long-Range Horizontal UZ
Transport
There is a feature of the INEEL UZ, probably associated with basalt-sediment interfaces, that conducts fast and continuous flow over km-scale distances.
The INEEL UZ must have extreme anisotropy, in excess of previous estimates.
A simple Darcy’s law calculation predicts tracer arrival as well as, or better than, detailed numerical modeling based on Richards’ equation.