A simulation study of infiltration into surficial sediments at the Subsurface Disposal Area, Idaho National Engineering Laboratory
Soil moisture monitoring data in the surficial sediments at the Subsurface Disposal Area (SDA) at the Idaho National Engineering Laboratory were used to calibrate two numerical infiltration models. The calibration was performed with the ultimate goal of providing a reliable estimate of hydraulic properties and infiltration amounts to be used in other modeling efforts. Two neutron probe access tubes and a tensiometer nest were monitored from 1986 to 1990 and again during 1993. The field measurements of moisture content and matrix potential inside the SDA were used as calibration data for the two locations. The two locations showed vastly different behavior, which was well captured in the models. The average root mean square error between simulated and measured moisture contents over the simulation period was 0.03 and 0.06 for the two locations. The hydraulic parameters resulting from the calibration compared favorably with laboratory and field scale estimates. The simulation results also provided the opportunity to partially explain infiltration and redistribution processes occurring at the SDA. The underlying fractured basalt appears to behave similar to a capillary barrier. This behavior inhibits moisture movement into the underlying basalts until moisture contents in the overlying silts approach saturation. As a result, a large proportion of recharge occurring at the SDA may be due to spring snowmelt, when the surficial sediments become nearly saturated. The results also indicated that a unit gradient boundary condition (free drainage due to gravity) at the bottom of the silts is not appropriate because of the very low relative hydraulic conductivity of the basalts. Finally, the amount of water moving into the SDA subsurface from spring snowmelt appears larger than cumulative snowfall, indicating that snow drifting due to local topography as well as current snow management practices may have a substantial influence on local infiltration.
- Research Organization:
- EG and G Idaho, Inc., Idaho Falls, ID (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC07-76ID01570
- OSTI ID:
- 10192322
- Report Number(s):
- EGG-WM-11250; ON: DE95002050; TRN: 94:022735
- Resource Relation:
- Other Information: PBD: Apr 1994
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
IDAHO NATIONAL ENGINEERING LABORATORY
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE FACILITIES
WATER INFLUX
SOILS
HYDRAULIC CONDUCTIVITY
FLOW MODELS
WATER SATURATION
ATMOSPHERIC PRECIPITATIONS
GEOLOGY
CLIMATES
GROUND WATER
EXPERIMENTAL DATA
COMPILED DATA
052002
053001
WASTE DISPOSAL AND STORAGE
SITING