Watching the water in Namibia

Wood & Douglas’s wireless network is monitoring vital water supplies at a Namibian fluorspar mine. Kate O’Flaherty reports

Watching the water in Namibia

Wood & Douglas has designed and implemented a wireless network to provide flexible monitoring and control of the water supplies at Okorusu, an open-pit fluorspar mine near Otjiwarongo in north-central Namibia.

Water management was a major issue for the Okorusu mine. The Namibian mining industry has high demands to process mined ore: water is a precious commodity and a critical production element.

In partnership with local company Desert Technical Solutions (DTS), Wood & Douglas installed instruments to monitor water flow, reservoir levels and the variable speed drives of the pumps at Okorusu Mine.

Borehole monitoring
Okorusu Mine receives its water supply from two boreholes, and has also instigated a recycling programme to make use of slimes water produced by the open-pit mining process.

The Homestead borehole is 9 kilometres to the south of the mine, with the Okorusu borehole 5 kilometres to the north. At each borehole and at the slimes dam, pump stations have been built to push water to the mine works. Given the distances involved, pumping can be problematic. This makes early detection of pump defects or a possible pipe burst essential to maintain rates of excavation.

But the mountainous terrain posed a challenge: no line of sight was available between any of the pump sites and the control room mast. Therefore, a repeater station was built on the mountain. With site construction provided by the Okorusu Mine, DTS was able to install the mast and a self-contained 12V DC solar power supply with battery backup.

Wood & Douglas’ Ethernet radios provided a backbone infrastructure for the Okorusu water control and monitoring system. To create the Ethernet network between the boreholes, repeater station and control room, Wood & Douglas deployed its Insight radios, operating on the 5.4GHz frequency.

‘You need to make sure the supply is consistent,’ says Grant Notman, head of sales and marketing at Wood & Douglas. ‘There is a pipe line with pumps on it and radio signals go to a room to say if it’s working or not.

‘It’s a long distance and it’s not line of sight: to link between them was complicated. That made it an exciting application for us. It was an Ethernet connection into it - radio across and Ethernet signal out - but we got it across the distance.’

Okorusu’s decision to opt for an IP-based Ethernet platform was driven by the need for interoperability. The aim was to integrate the water control and monitoring with the existing IT network, ensuring connectivity for troubleshooting from anywhere in the network, including over or through virtual private networks (VPNs).

‘If you compare Serial over wireless and Ethernet over wireless networks, adopting an Ethernet platform was far more cost effective to implement and maintain,’ says Jaco Wiese, Okorusu IT administrator.

The Insight radios are rapid to install and set up, providing high performance wireless video and telemetry transmission. Insight is a rugged, reliable system, with robust IP66 rated weatherproof housing.

It is capable of operating through the severe local electrical storms and temperatures as high as 50c. The tough enclosure also keeps out the weather, and protects the wiring from the local baboon population - which is known to climb equipment and can be destructive.

Okorusu has become Namibia’s largest bulk exporter to destinations outside Africa. High demand comes from European markets where fluorspar is used as a raw material in the manufacture of nuclear products and for water fluoridation.

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