[en] The purpose of this study was to examine the design sensitivity of various components of the Exploratory Shaft Facility (ESF) to the geotechnical and hydrological data needed for design and construction of the facility. The data fall into two broad categories: data used directly in design calculations and data used indirectly in the design and construction process. Design elements are much more sensitive to data that is used directly in design calculations than to the data that is used indirectly, and the degree of sensitivity can be used as a means of prioritizing the data gathering activities. The geotechnical and hydrological parameters that are directly used in design studies, the design elements that are effected by the parameters, and the relative sensitivity to the given parameter are briefly summarized. 9 refs., 10 tabs