Electromagnetic Data Acquisition Techniques For Landfill Investigations

Shallow electromagnetic methods (EM-31) provide an effective<br>means of locating and mapping landfill boundaries and lateral<br>change in waste mass composition. However, the variable nature<br>of landfilled materials tends to complicate the electromagnetic<br>field surveys. Survey grid layout, traverse line spacing and<br>sample interval, and the recognition of signal aliasing during<br>data collection are problems encountered during the survey planning<br>and data acquisition. This paper presents data acquisition<br>techniques which can reduce signal aliasing problems associated<br>with landfill electromagnetic survey.s. The techniques include<br>set-up of field survey grids: determination of appropriate<br>traverse line spacing, and when and how to change spacing based<br>on field data: and a method for varying the sample interval while<br>traversing.