On September 28, 2006, in the Vlinderbuurt in Kralingen The sunken fountain by visual artist Hans van Lunteren was unveiled. The artwork is located on a square near the Jodenvijver, corner of Eikenpage and Vredenoordlaan. In 1990, the soil remediation of the Gasfabriek site was started in the former sub-municipality of Kralingen – Crooswijk. More than 15 years later, the visible work was completed and the area was redesigned. However, the underground soil remediation of the deep groundwater will continue for years to come. A water purification station was built in the Vlinderbuurt for this purpose. In 2001, CBK Rotterdam proposed to the sub-municipality to commission artist Hans van Lunteren to design a work of art as a tribute to the soil remediation of the former Gasfabriek site. After research into the existing water flows, tap water, heated groundwater, rainwater, ditch water and purified groundwater, the artist was particularly inspired by the latter to design a sunken fountain. The groundwater is pumped up and purified in a station in the Vlinderstraat. After purification, the water is pumped to the fountain. Above ground, a metal grid has been installed in the floor, in which the leaves of the ash, birch, maple and poplar are incorporated: trees that occur in the immediate vicinity. Around this grid, at the same height as the paving, there is a bluestone border. The composition of the leaves is built up from a slight rotation, as if the wind has created a small vortex with a still interior. The sunken fountain is visible through the grid: an armature of three consecutively stacked bowls in size, into which the pumped water falls. When passing the leaf grid in the floor, the sound of the quietly falling water is audible. Many residents throw a coin in The Vsunken fountain, as if it were a wishing well.