SLOPE STABILITY MONITORING
configured to react to the detection of movement by a tilt sensor by automatically increasing its sampling frequency and that of its neighbouring tiltmeters to build a more reliable dataset or ‘ wake up ’ a camera which can send a highresolution image of the event to stakeholders anywhere in the world . In this way , battery life can be preserved by operating for the bulk of the system lifetime in a background mode with relatively sparse sampling , but switching to near real-time reporting in the event of a significant breach of pre-set trigger levels .
“ The process of setting up a wireless monitoring system can be so quick that it has found a role in emergency situations . A number of users around the world , particularly in areas of seismic activity , have invested in relatively basic kits permanently on-hand to deploy in the field following a slope failure . Deployed and fully functioning within a couple of hours , it can guide decision-making about whether it is safe to continue working in the vicinity of the failure , for example to use a haul road on , or below an apparently unstable slope .”
GKM and Worldsensing join forces for Canadian tailings dam monitoring
Tailings dams are dynamic structures that can occasionally fail with tragic consequences for nearby communities and ecosystems . As a result , the mining industry has increasingly recognised the need to monitor these structures as part of moves to provide early warnings and remedial actions when a failure is imminent . And options for monitoring have improved vastly in recent years .
At a mine in northern Quebec in Canada , for example , the geotechnical engineering firm GKM Consultants and the monitoring technology vendor and connectivity provider Worldsensing have joined forces to monitor an iron ore tailings dam stretching over several square kilometres . The mine is a large producer of iron and the production of concentrated iron added daily load to the tailings dam . Additionally , the mine is located in a subarctic zone which means site visits are challenging due to regular heavy snowfalls and temperatures are as low as -40 ° C in the winter .
To overcome these challenges , GKM Consultants chose to monitor the site using a wireless network in areas that might be prone to critical failures . The IoT-based wireless monitoring solution , from Worldsensing , uses a wide-area network system called LoRa which is a long range , low power connectivity technology .
GKM Consultants selected the Worldsensing technology because it was the best fit for the project . The optimal combination between a 900 Mhz long-range radio communication ( LoRa ) with a signal sensitivity of 120 dBm is capable of providing longdistance communications , with very little power consumption . Hence , battery-powered monitoring equipment can be installed on site and then left to run on its own for up to a decade without maintenance .
The monitoring solution is able to cover all the critical areas of the tailings dam . Worldsensing technology collects data from a large quantity of piezometers installed out in the field and forwards this in near real-time to a monitoring dashboard belonging to the mine owner .
Each sensor is fitted with a battery-operated
Geotechnical engineering firm GKM Consultants and the monitoring Worldsensing data logger technology vendor and connectivity provider Worldsensing have joined that transmits readings to forces to monitor an iron ore tailings dam in Quebec a central gateway according to a predetermined schedule . All data n Receiving data from crack meters to track loggers on the site are able to communicate movement across surface cracks of the directly with the gateway at the preferred slopes sampling rates thanks to LoRa . In one case n Borehole extensometers for monitoring where there were natural barriers blocking the vertical deformation at various depths line of sight between a logger and the gateway , n In-place inclinometers ( IPIs ) for horizontal the system configuration was adjusted to ensure displacement monitoring . that one reading per hour would be captured . A From an environmental perspective and key component that was taken into account is around the tailings structure , data is collected that the Worldsensing technology is flexible and from rain gauges to track rainfall and from water able to integrate any type of vibrating wire quality probes for ground water quality instruments across a large area , which could measuring . For all this , IoT-based wireless prove valuable if the mine needed to expand . monitoring is vastly more cost effective , safe and
Connectivity is key in mines , especially efficient than sending technicians out to collect around tailings dams and slopes where sensor readings by hand . Worldsensing monitoring points are spread over a large area estimates that monitoring can reduce costs by and the work environment is changing up to 55 % compared to carrying out manual constantly . The tailings facility monitoring readings after five years , and by 87 % after 20 solution will ensure accurate and secure data years . transmission and can seamlessly integrate with “ Despite these clear advantages , wireless the mine ’ s existing IT infrastructure . monitoring of tailings dams is still relatively rare With the Worldsensing technology being used in the mining industry . This is partly due to a by more than 100 mines across over 20 historic lack of interoperability between sensor countries , key application scenarios for IoTbased monitoring around tailings dams and of the importance of monitoring .” A study in
systems and networks and a lack of awareness
slopes include obtaining monitoring data from : 2019 by the Church of England , a major mining n Water level meters company investor , revealed the existence of at n Piezometers in boreholes for measuring least 1,700 unmonitored tailings dams water pressure within the dam worldwide . However , the trend towards installing
108 International Mining | AUGUST 2021