The Application Of An Integrated Magnetometer/Global Positioning System For An Unexploded Ordnance Investigation

Geophysical techniques have been used for many years to detect unexploded<br>ordnance (UXO) buried in the subsurface. UXO detection can be performed by using<br>either “mag and flag” methods where anomalous metallic items are located without data<br>collection and flagged for excavation or dug immediately, or using a data collection<br>system where anomalous areas are selected from the data record and the positions are<br>reacquired for excavation. In recent years, recorded data surveys have begun to take<br>precedence over unrecorded surveys.<br>There are two elements to a successful recorded data geophysical survey:<br>1. Data collection (magnetic/electromagnetic field)<br>2. Location tracking.<br>Having only one of the above elements without the other yields nearly useless<br>information and certainly makes for an unsuccessful survey. Traditional methods of<br>tracking the location of data collected by the geophysical survey instrument have been to<br>use either a time/distance method or a mechanical measurement tool (i.e. wheel<br>odometer). Technological developments in survey equipment and the Global Positioning<br>System (GPS) have added a new way of tracking position during surveys in select<br>environments.<br>A geophysical investigation was conducted at a former military range in Mississippi<br>using an integrated magnetometer/GPS system. The use of the integrated system yielded<br>extremely good results in open areas but had limited use in areas under heavy tree<br>canopy. Results of the surveys performed indicate that the integration of GPS with<br>geophysical instruments is a viable tool and may become the standard operating<br>procedure in certain environments. The limitations of the integrated system primarily<br>stem from the ability of the GPS system to “speak” with satellites through tree cover.