Development Report on the Idaho National Laboratory Sitewide Three-Dimensional Aquifer Model

Thomas R. Wood ; Catherine M. Helm-Clark ; Hai Huang ; Swen Magnuson ; Travis McLing ; Brennon Orr ; Michael J. Rohe ; Mitchell A. Plummer ; Robert Podgorney ; Erik Whitmore ; Michael S. Roddy

关键词: S//MATHEMATICS;    COMPUTING;    AND INFORMATION SCIENCE;    AQUIFERS;    BOUNDARY CONDITIONS;    CALIBRATION;    FLOW MODELS;    HYDRAULIC CONDUCTIVITY;    IDAHO;    SNAKE RIVER PLAIN;    STABLE ISOTOPES;    STEADY-STATE CONDITIONS;    TRANSPORT;    WATER Operable;   

DOI  :  10.2172/918698
RP-ID  :  INL/EXT-07-13337
PID  :  OSTI ID: 918698
Others  :  TRN: US200822%%592

学科分类：社会科学、人文和艺术（综合）

美国|英语

来源: SciTech Connect

【 摘 要 】

A sub-regional scale, three-dimensional flow model of the Snake River Plain Aquifer was developed to support remediation decisions for Waste Area Group 10, Operable Unit 10 08 at the Idaho National Laboratory (INL) Site. This model has been calibrated primarily to water levels and secondarily to groundwater velocities interpreted from stable isotope disequilibrium studies and the movement of anthropogenic contaminants in the aquifer from facilities at the INL. The three-dimensional flow model described in this report is one step in the process of constructing a fully three-dimensional groundwater flow and contaminant transport model as prescribed in the Idaho National Engineering and Environmental Laboratory Operable Unit 10-08 Sitewide Groundwater Model Work Plan. An updated three-dimensional hydrogeologic conceptual model is presented along with the geologic basis for the conceptual model. Sediment-dominated three-dimensional volumes were used to represent the geology and constrain groundwater flow as part of the conceptual model. Hydrological, geochemical, and geological data were summarized and evaluated to infer aquifer behavior. A primary observation from development and evaluation of the conceptual model was that relative to flow on a regional scale, the aquifer can be treated with steady-state conditions. Boundary conditions developed for the three-dimensional flow model are presented along with inverse simulations that estimate parameterization of hydraulic conductivity. Inverse simulations were performed using the pilot-point method to estimate permeability distributions. Thermal modeling at the regional aquifer scale and at the sub-regional scale using the inverted permeabilities is presented to corroborate the results of the flow model. The results from the flow model show good agreement with simulated and observed water levels almost always within 1 meter. Simulated velocities show generally good agreement with some discrepancies in an interpreted low-velocity region near the toe of the Arco Hills. This discrepancy persisted in each of the aquifer bottom thickness scenarios that were simulated precluding decisions on which aquifer bottom thickness to use in transport simulations. When joint-calibration was performed using both water levels and velocities assigned as calibration targets, the discrepancy was prevented. This result highlighted the need to consider multiple calibration objectives and not rely solely on calibration to water levels. The next and last step in the process of constructing a fully three-dimensional groundwater flow and contaminant transport model will be calibration directly to transport from facilities. This last step will likely require further modification of the velocity fields resulting from the three-dimensional groundwater flow model presented in this report.