Use of Dragflow EL 5 for major overhaul of Waternet filter basins

Working on behalf of water company Waternet, Van Gansewinkel Industrial Services Amsterdam is currently doing a major overhaul on the filter basins of the company’s water pumping station in Vogelenzang. For this work, Van Gansewinkel uses a Dragflow EL 5 wear resistant slurry pump supplied by Eekels. ‘And it does an excellent job’, says Rob Lippens, operational manager at Van Gansewinkel. ‘This pump is not only much cheaper than a suction excavator, it also does the job more efficiently and faster. In short, a perfect choice!’

Waternet

Operating on behalf of the Amstel, Gooi and Vecht Water Board and the City of Amsterdam, Waternet is to address all stages of the water cycle: supply of drinking water, treatment of waste water, keeping surface water clean and maintaining its level, and groundwater level management.  For drinking water supply, Waternet extracts water from the Amsterdam Water Supply Dunes near Zandvoort and from the Bethune polder near Loosdrecht, which is subsequently treated in a number of steps.

Water treatment process

Step three in the water treatment process – after pre-treatment and natural cleaning – is rapid sand filtration in the filter basins of the water pumping station in Vogelenzang. In this step, the water is distributed over large basins filled with sand. When the water seeps through the sand layer, harmful substances are left behind. If the sand is saturated with dirt particles, aerators on the bottom of the basins ensure that the dirt is rinsed off from the bottom upwards, allowing it to be discharged via channels.

Major overhaul

Rob Lippens: ‘To assure the quality of the treatment process, these aerators need to be replaced. For this, all sixteen basins, each containing some 60 cubic metres of sand, need to be drained, representing a total of almost 1,000 m³.’  The procedure is quite straightforward: using a Dragflow EL 5 slurry pump, Van Gansewinkel pumps the sand from one basin to the next. After cleaning the empty basin and replacing the aerators, the sand is pump backed and work is continued with the next basin. After completion of the maintenance work, the filter basins can be used again for a long period of time.

Wear resistant

Lippens is quite satisfied with the slurry pump supplied by Eekels. ‘The pump does a fine job, so long as enough water is added to the sand. The sand is heavy and coarse and therefore highly abrasive. It’s not hard to imagine what this does to a pump. After draining the first basin we thoroughly inspected the pump and, apart from the paint which had obviously come off, it still looked perfect. This is no wonder because all wear-sensitive parts are made of chrome steel’.

Cost benefits

Lippens is also very happy with the cost aspect:  ‘Normally you would use a suction excavator for this kind of work. Such an excavator first sucks up the sand and then has to be emptied. The Dragflow pump performs both operations simultaneously – and in just two-thirds of the usual time. This saves time and therefore money. And, of course, such a pump is many times less expensive than a suction excavator’.