HOT WATER BOREHOLE SOLUTION FOR ETHIOPIAN ROADWORK

By solving the challenge of pumping boiling groundwater to surface, water specialist Grundfos has allowed a road construction to proceed through an extremely hot and dry area of desert in Ethiopia.

The road upgrade project – conducted by Grundfos client Defence Construction Enterprise – was close to Ethiopia’s most active volcano, Erta Ale. This basaltic shield volcano is continuously active and is well known for its persistent lava lake.

According to Grundfos Country Manager for Ethiopia, Maru Necho, the volcanic conditions heat groundwater to temperatures of 82°C – making it difficult to extract the water for use above ground.

As there was no available surface water in this harsh desert environment, it was essential that water be drawn from underground sources to allow the road project to be successfully done. In addition, the road construction project was making use of asphalt concrete which uses far more water than the usual petroleum-based asphalt method.

“Our customer had tried several other solutions to secure the water supply they needed, but these did not last long enough to be productive,” says Necho. “In preparing our solution, Grundfos consulted with expert engineers and considered every technical aspect of the project. This allowed us to develop a response that would be the most suitable for this challenging application.”

Necho notes that a key challenge given the high water temperature at the pumping depth of some 430 m below surface was the cooling of the submersible pump. This type of extreme heat would usually lead a motor to frequently stop and start, inevitably causing premature failure.

“We installed a Grundfos SP60-13 six-inch borehole pump, constructed of EN1.4401 stainless steel fitted with a 26kW rated motor,” he says. “It was constructed of high-alloy austenitic stainless steel for optimal corrosion resistance, as well as fluoro carbon synthetic based rubber or FKM rubber parts which are excellent in withstanding high temperatures.”

This configuration is able to deliver water at 5,2 litres per second to the surface. Grundfos also installed a control panel fitted with specialised temperature sensors, to protect both the pump and the motor.

“We used a Pt1000 sensor with a soft start control MP204 motor protection unit, which was set to stop the pump, in the event that the motor temperature reaches 90⁰C,” he says. “This gives our customer a reliable water supply, while at the same time protecting the lifespan of the pump.”

Necho highlights that the customer was very happy with the result, and also with how Grundfos had been able to develop a solution in good time to facilitate the project. He says the first phase of the road project involved two boreholes, and Grundfos was also contracted to supply more application sites for the project’s next phase. There will, in time, be an added community benefit resulting from the success of Grundfos’s work.

“After the roads project is complete, the boreholes will be handed over to the communities in the area as a source of boiling water,” he says.