DELINEATION OF COAL TAR IN BEDROCK AT A FORMER MGP SITE IN UPSTATE NEW YORK

摘要

After coal tar was observed in limestone bedrock beneath a well-defined and mostly competent glacial till at an upstate New York site, a combination of intrusive and non-intrusive methods was applied to define structural controls and to generate clues regarding extent. New York State Geological Society bedrock maps, high altitude photographs, and topographic map fracture trace analysis, as well as direct measurements of strike and dip of bedrock and till structure, were applied to assist in locating boreholes to delineate the extent. Surface seismic refraction was undertaken to map top of till and bedrock to determine if high-angle, low velocity zones were present. Square-array resistivity was used to identify potential fracture orientation within the till and bedrock. Other fracture orientation and groundwater productivity data (from fractures) were acquired using standard borehole geophysical methods. Confirmatory drilling was used throughout the process to provide "ground truth" regarding the bedrock fracture system conceptual model. Ultimately, square-array resistivity results and direct measurement of bedrock outcrops proved most useful in determining where to drill and most valuable in refining the conceptual model.