No fast and reliable method currently exists for characterising contaminated soil in situ. Samples are most commonly extracted for laboratory analysis, which is time-consuming and expensive. The SOIMON project, a collaborative EU project being conducted by a consortium of companies including TWI, aims to develop an automated system capable of performing in-situ and real-time soil analysis for volatile organic compounds (VOCs) and heavy metal inspection, identifying and characterising pollution in a wide range of terrains. The project also aims to develop a structural health monitoring system to assess the integrity of the drilling bore pipes for real-time structural monitoring and a passive and active damping system to protect sensitive electronics from the high level of vibration generated by the sonic drilling.
SOIMON integrated technologies
The SOIMON prototype integrates in the drilling pipe the following fully developed technologies:
- surface acoustic wave (SAW) sensor with improved sensitivity and reduced weight to identify toluene and dichloromethane contamination, selected as model gases for BTEXs and chlorinated hydrocarbons
- radiometric sensor to identify heavy metal contamination
- monitoring sensors based on acoustic emission, accelerometers and strain gauge to monitor torque
- wireless communications for real-time data transmission
- SOIMON software environment for real-time soil analysis and structural health monitoring while drilling
- passive anti-vibration system providing 90% damping between 50Hz and 200Hz
- active damping system providing up to 4g vibration reduction.
The SOIMON prototype (Figure 1) has been tested and validated on a contaminated site, where it was able to identify in real-time the VOC contamination in the terrain (Figure 2). During drilling the system withstood vibrations up to 80g and a shock of up to 120g, confirming the effectiveness of the anti-vibration system and the efficiency of structural health monitoring sensors throughout the drilling process.