FUTURE DIRECTION-CLOSURE OF THE SHOAL TEST AREA

Several important areas of work must be addressed and resolved before closure of the Shoal site can be completed. The three-dimensional, numeric groundwater flow model must be validated to reduce uncertainty in predictions of radionuclide transport and to build confidence in the monitoring network. DRI is a leader in the area of stochastic model validation as evidenced in two recently published journal articles (Hassan, 2004a, 2004b ). DRI's expertise in validating stochastic models is currently being applied to develop the validation strategy for the Shoal model.

The groundwater-monitoring network for the site is being designed by DRI. Flow predictions produced with the transport model are being used to identify the optimal locations and depths for drilling the monitoring wells. Installation of monitoring wells and the model validation process merge in what is called the "proof of concept" whereby DOE and the state of Nevada determine, over a five-year period, that the model and monitoring system are performing well. As data are collected, uncertainty in the model predictions will decrease, and confidence in the site closure design will increase.

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Hassan, A.E. 2004a. Validation of numerical ground water models used to guide decision making. Ground Water 42, no. 2: 277-290. Reprinted from Ground Water with permission of the National Ground Water Association. Copyright 2004.

Hassan, A.E. 2004b. A methodology for validating numerical ground water models. Ground Water 42, no. 3: 347-362. Reprinted from Ground Water with permission of the National Ground Water Association. Copyright 2004.