SYSTEM ASSESSMENT CAPABILITY - AN INTEGRATED MODEL FOR SIMULATING THE TRANSPORT, IMPACTS AND REMEDIATION OF CONTAMINANTS AT THE HANFORD SITE

Considerable effort has gone into the characterization of the saturated and vadose zone hydrology at the Hanford Site so that contamination remaining from past operations can be effectively remediated. Research has also been done to identify the location and quantity of waste remaining at the Site and the effects various contaminants can have on human and ecological health. The resulting understanding of each of these topics must be collectively taken into account as decisions about Hanford cleanup are made. To facilitate that process, a system of numerical models was assembled to simulate the inventory, release, environmental transport and impacts of Hanford contaminants. This set of models and the associated data is called the System Assessment Capability.

The capability simulates contaminant release, migration, and fate from the initiation of Hanford Site operations in 1944 forward. It illustrates historical and near-term influences on long-term risk and impact, and therefore, provides an opportunity to history match to observed events using waste site characterization data and results of groundwater monitoring. The capability is a stochastic simulation tool able to address 1000 waste discharge and disposal sites and multiple contaminants for a period of 10,000 years. It has been designed to also simulate a deterministic case as a single stochastic realization. Human health and ecological risks as well as impacts to the regional economy and local cultures are quantified.

The capability was first developed in 2001 and has undergone considerable modification as recent research has provided improved understanding of contaminant inventory, transport and impacts. The capability is being used to prioritize remedial actions, evaluate alternatives, and communicate likely future impacts of Hanford on the environment.