A large Northern Cape farming operation recently moved to drip-irrigation to conserve water. This required cleaner water from its dams – a challenge that Integrated Pump Rental said it could help solve.
Using its specialised SlurrySucker desilting solution, the company desilted the first of four dams to prove the concept to the customer. Less silt meant not only cleaner water, but higher storage capacity in the dam.
“The customer was so pleased with the result that they have asked us to tackle the other three dams,” said Rental Development Manager Ruaan Venter. “Dirty water would have clogged their drip-irrigation pipes and prevented the whole system from working.”
Venter added that this was the first time that the company’s robust SlurrySucker equipment had been used in an agricultural application.
“Our traditional focus is in the mining industry. But our experience in removing silt from process ponds on mines was ideal for this work in the agricultural sector.”
In these applications, the SlurrySucker is mounted on a floating barge that is pulled back and forth across a dam. A dewatering pump feeds the surface water down to a dredge-head, which agitates the silt using seven bar of pressure through 16 nozzles. The thick, agitated material is then pumped out of the dam using a fit-for-purpose slurry pump.
One of the key advantages of the system is that it does not damage the clay lining or geomembrane that lines the dam. Previous efforts to desilt these dams had been conducted with tractor-loader-backhoes (TLBs) and this punctured the lining and was unsuccessful.
“We make sure that our agitation heads are operated at a suitable distance from the floor of the dam. We also use specially designed hose floats to keep the hoses and electrical cables on the water surface. This avoids any possible damage caused by submerged hoses being dragged across liners.”
There was vegetation rooted in the silt, which had the potential to clog the suction heads. The company used a vortex impeller solution to deal with this.
The efficiency of the SlurrySucker meant that an 80-metre long, 25-metre wide and about two-metre deep dam could be desilted in just one week. And this was despite a high slurry content of about 60%.
“Using one 37 kW submersible slurry pump on the barge, we were able to pump at about 250 cubic metres an hour through a six-inch pipeline. This converted to between 50 and 60 dry tonnes an hour.”
Venter said the customer had entered into a maintenance contract with Integrated Pump Rental to ensure that the dams are regularly desilted.