Sensitivity to Formation Porosity of Contaminant Transport from Nevada Test Site to Yucca Mountain

Abstract

This study quantified the sensitivity of advective contaminant arrival time to the porosity of hydrogeologic units (HGUs) for groundwater transport from the Nevada Test Site (NTS) to the Yucca Mountain (YM) area in the United States. Advective arrival time of contaminants associated with underground nuclear detonations was obtained by using particle tracking on the basis of flow velocities from the Death Valley Regional Groundwater Flow System (DVRFS) model and porosity information for the HGUs along the flowpaths. The objectives were to (1) determine which HGU’s porosity is influential in contaminant advective arrival time from the NTS to the YM, and (2) apportion uncertainties in contaminant advective arrival time to the uncertainty contributions from individual HGU porosity. Over 90% of the uncertainty in advective transport arrival time from the NTS to YM could be described by uncertainties in porosity values of two of the 27 HGUs present in the DVRFS model. The study was significant for optimizing resources in field characterization to reduce uncertainty by targeting HGUs contributing the most uncertainty.