Old Treatment Plant was built based on the design by William Heerlein Lindley. Project was completed in 1906 and had functioned as a waste water treatment plant until 1967 when a new mechanical biological treatment plant at Imperial Island (Císařský ostrov) was opened. The complex of the Old Treatment Plant was declared a heritage site in 1991 and in 2010 it was listed as a national cultural monument. The plant areal was hardly damaged during 2002 and 2013 floods.
Extensive restoration works was carried out by GEMA ART on the premises of the treatment plant between 2015 and 2018. The expert works was focused on restoration of metal elements, such as sluicegates, hand-rail smith work, pumping structures, air-handling gears, transmissions, boilers, and metal walkways as well as on restoration of construction works, reinforced concrete elements of the sand catcher and sedimentation tanks.
After the completion of the works, GEMA ART participated in the preparation of the registration of this monument on the tentative list for inscription in the UNESCO World Heritage List. This important technical heritage site and the executed restoration works results were presented during TICCIH (The International Committee for the Conservation of the Industrial Heritage) Congress in Santiago de Chile at 13 – 14 September, 2018 (see Presentation). The Old Treatment Plant in Prague was successfully registered on the tentative list on 16 July 2020 (see UNESCO).