Vertical Profiling Data Sets for Improved Characterization of Hydrologic Units Influencing Contaminant Migration in Strongly Heterogeneous Triassic Sediments

Abstract

A large, former state-owned East German chemical park, has contaminated the subsurface. These contaminants migrate through a variably-lithified sequence of fractured, Triassic, interbedded clay/shale and sand/sandstone of fluvio-lacustrine origin. Conventional characterization techniques have indicated that contamination by volatile organic compounds (VOCs) exists in the source zone as DNAPL and in a dissolved phase plume stretching hundreds of metres down-gradient. In 2011, high-resolution core and borehole methods were applied at two cored holes: UoG1, 42.5 m deep, in the source zone; and UoG2, 68 m deep, 500 m down-gradient. This study demonstrates that high-resolution vertical profiles of contaminant concentrations, at a spatial scale informed by observed textural layering and fracture frequency, provide the basis for improved delineation of laterally continuous hydrologic units. These data were corroborated with conventional geophysical logs and detailed depth discrete hydraulic head profiles from MLSs, providing an improved site conceptual model for groundwater flow and contaminant transport.