INITIAL GRADIENT IN A DENSE GLACIAL TILL.

Abstract

Hydrogeology and geochemistry, critical factors in evaluating containment transport and radiation safety, have been studied at the Bruce Nuclear Power Development site, Ontario, Canada, where low to medium level wastes are stored in in-ground reinforced concrete structures. These structures, located in dense glacial till, are provided with a subsurface drainage system. The study included the determination of the tritium profiles in the till soil; the results indicate that groundwater flow appears to deviate from Darcian behavior. The permeability of the till soil was then studied in the laboratory by means of a special apparatus that permits the accurate measurement of minute flow under low hydraulic gradients. The test results show that there exists an initial gradient below which the permeability coefficient is either zero or significantly smaller than that at higher gradients.