oa High-resolution helicopter geophysics in support of a Defence engineering project

In October and November of 2008, Battelle and AECOM conducted an extensive airborne project at an Australian RAAF base in support of a base expansion project. The purpose was to identify, document and if possible, mitigate potential sources of groundwater contamination and related pathways. The two boom-mounted airborne systems that were deployed were designed for detection and mapping of shallow buried metals. An area of 1740ha was s urveyed with a combination of magnetic gradiometer and time-domain electromagnetic induction.

Approximately 1230ha of this was flown at low altitude (1-3m) with a 16-sensor vertical gradient system (VG-16). The remaining area was flown at higher altitudes due to vegetative cover. Areas of special interest totaling 290ha were followed up with an 8-receiver low altitude electromagnetic survey (TEM-8). Ground follow-up with excavation was then conducted on a selection of anomalies to identify their causative sources.

A combination of historical records, aerial photographs, GIS and modern geophysics were combined to provide a unique picture of the site prior to a new round of base expansion and construction. Targets identified included both documented and undocumented waste pits and trenches, gun emplacements, buried planes, structural foundations, and naturally -occurring magnetic rock and soils. The entire 1740ha of VG and 290ha of EM were surveyed in less than 5 weeks at a resolution approaching that of ground-based systems.