Gruba Kaśka (Fat Kate)

Construction of “Gruba Kaśka” took eleven years; it started to operate on 22 September 1964. On that day, for the first time water flowed which “Gruba Kaśka” collected from the sandy layers on the bottom of the Vistula. The facility was built in the Vistula riverbed, at 509 km of the river’s navigational route. “Gruba Kaśka” is a cylindrical well which pumps water from a system of eleven drainpipes. The drainpipes lie at a depth of 4-8 m and their combined length is 1,472 m Polish engineer, Włodzimierz Skoraczewski was the first in the world to develop the method of collecting water from the bottom of the river. Today, around the world this method is called “the Warsaw intake”. Before the Polish engineer’s methods were applied, the filtration intakes were built on land. After several years of use the equipment would become blocked by various layers of waste forming on it. This resulted in the closure of off-shore intakes and the construction of a new ones, and that required significant financial outlays.

In the “Warsaw intake” method water is collected from several radially placed drainpipes that lie under the riverbed, in natural filtration deposits at the depth of about 6 m. There is sandy substratum on the bottom of the river, which is in constant motion (it shifts). It makes a natural replacement of filtrating deposits. The flowing water gets through the changing filtrating environment found above the drainpipes. The purified water is transported to land by a pipeline.

One to two vessels: “Chudy Wojtek II” and modern “Chudy Wojtek III” have to constantly sail around “Gruba Kaśka” so that the method can function effectively. The name of the vessel comes from its designer, engineer J. Wojtkowski. They are the so-called ‘aerators’. The pumps located on the vessel rinse the most polluted deposit layers under big water pressure and loosen the sand above the under-riverbed drainpipes. The river’s current constantly brings new pollutants, which need to be constantly removed. Furthermore, the sandy bed has to be constantly aerated so that the drainpipes do not become blocked. That work is done by the abovementioned vessels. For that reason there is a saying among the technical waterworks staff that “Chudy Wojtek” looks after “Gruba Kaśka” well.

“Gruba Kaśka” collects and pumps water non-stop in quantities of 90,000-120,000 m3 daily. The well can be accessed from the Praga side through a 300 m tunnel under Vistula’s bottom.

“Gruba Kaśka” is the biggest filtration facility of its kind in Europe.