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High tech dam safety

The Höjtärn tailings pond is equipped with a high-tech surveillance system, which uses fibre optic sensors within and around the dam and ponds to monitor dam safety in real-time.

The system was installed in the spring 2014 and allows staff in the concentrator control room to analyse various real-time measurements, including within and around the dam. This access to real-time information enables teams to respond quickly with the appropriate action in the event of issues that may result in excessive seepage or even compromise dam safety.

Enhanced dam safety

"This state-of-the-art online system has significantly improved our dam monitoring capabilities," says Ronnie Furberg, Dam Supervisor. Prior to the system, monitoring dam safety was dependent on manual inspections and measurements taken at the inlet water pipes and drainage drains. Such measurements were time consuming and gave a less accurate picture of dam security than real-time sensors that are capable of measuring processed within the dams.

"When seepage in the dam exceeds limits an automatic alert is sent directly to the concentrator, which considerably enhances safety and our ability to respond appropriately. In addition, the system allows us to identify weaknesses that cannot be seen in a visual inspection of the dams," says Furberg.

High tech solutions 

The unique system combines state-of-the-art online measuring instruments, such as fibre optic sensors, with advanced data processing capabilities.

Three fibre optic cables have been installed at different levels within the dams to measure temperature, which can be used to quickly identify seepage points and flow through the dam. "By analysing various levels we can evaluate the stability of the dams and prevent undesired consequences. The quicker we can identify changes, the faster we can take action," says Furberg.

The ponds are equipped with 16 depth gauges that are also measured online, and act as an early warning system against significant leakages or dam failure. Eight wells that collect leakage from the dams before it is treated have also been equipped with online sensors and CCTV cameras to closely monitor the status of the wells.

Five dome cameras have been installed around the ponds that are programmed to automatically perform panoramic sweeps to monitor the ponds. Staff in the control room can take over the camera controls to investigate a particular area and teams are sent to carry out a site inspection if necessary. Daily physical patrols are also carried out.

Staff in the concentrator control room can analyse the data from the system with built-in tools, for example by viewing data as trend curves to help identify any anomalies.

Höjtärn tailings pond

The 230-hectare Höjtärn tailings pond is used to store sand and water from processes at Boliden's concentrator in the Boliden area. Following clarification, water is discharged into the Skellefteå River. The tailings pond was complete in 2011 and is surrounded by two dams, 14 m high and 3,000 m long respectively 11 m high and 900 m long.

Contact

Boliden Head Office

Boliden Group
Klarabergsviadukten 90
P.O. Box 44, SE-101 20 Stockholm
Tel: + 46 8 610 15 00
Fax: + 46 8 654 80 90