Use of magnetics for the location of environmental contamination

Abstract

ADI Services, in conjunction with the Geophysical Research Institute of the University of New England, have been utilising the TM-4 Imaging Alkali-Vapour Magnetometer to locate and validate the presence of buried ferrous items in contaminated areas. Unlike many conventional systems, the TM-4 enables the rapid collection of high resolution magnetic data. The data can be displayed as colour images and interpreted semi-automatically and/or manually. Flexibility within the TM-4 system enables irregular blocks to be surveyed without requiring the user to know the exact beginning and end coordinates of the survey lines. Two case studies are presented which demonstrate the effectiveness of high resolution magnetic surveys for contamnated site assessment. The first case study shows how the TM-4 system has been used for the detection of unexploded ordnance, associated ammunition components and fragmentation. The objective for the second case study was to locate one edge of a former waste burial pit which was known to contain significant quantities of ferrous waste. The contrast in the total magnetic field between the burial pit and the surrounding bedrock was easily recognised.