The Old Wastewater Treatment Plant complex, today offering an exceptional testimony of water management, architecture and technology at the turn of the 20th century, houses a set of surface and underground structures. The way the complex has been composed reflects the technological processes involved in wastewater treatment, which took place underground (the grit chamber and clarifiers).
The Old Wastewater Treatment Plant was built between 1901 and 1906 by the Quido Bělský construction company. In 1907, the treatment plant was put into full operation after a year of trials. It treated wastewater until 1967. Prague’s modern sewerage system was designed by Sir William Heerlein Lindley (born 30 January 1853 in Hamburg, Germany, died 30 December 1917 in Putney, Great Britain), the renowned water supply and sewerage engineer, who also designed other modern sewerage systems for major cities elsewhere in Europe. Lindley, who mainly worked in Germany, but also engaged in consultancy in other countries, was a great pioneer of environmental protection in wastewater treatment and contributed to the construction of modern water supply systems. Today, he is considered a figure of European stature. As he approached the design of each of his waterworks and sewerage systems as an independent project that factored in local conditions, all of his surviving technical facilities are unique.
The construction of Prague’s sewer network, which remains in operation to this day, began in 1899. The system of original trunk sewers forming the basis of the sewerage system was so sophisticated and well-executed that sewerage networks subsequently built in Prague could be connected to it seamlessly. The mechanical wastewater treatment design was at the heart of this project. Mechanical treatment was a principle that ensured the responsible removal of impurities from wastewater before it was discharged into the recipient – the Vltava river. For this to take place, the individual processes involved – mechanical treatment and the disposal of trapped undissolved pollutants – had to be unified with technical accessories into a single functioning unit. The technology was designed to work on the principle of gravity. In this process, the wastewater that was to be treated was drained via a gravity sewer system into a site beyond the city that was chosen because it had the lowest elevation and was as close as possible to the Vltava.
The Old Wastewater Treatment Plant remained fit for purpose for a full sixty years, before closing in 1967. It continued to be used for sludge management until the 1980s.
In the spirit of architecture from the time, the building is dominated by an asymmetrical middle section incorporating the main front entrance. The staircase at the façade end of this section leads to administrative facilities, beyond which there is a monumental hall. Lower longitudinal wings flank the central structure. The individual parts have different types of roofing: the wings and administrative facilities are covered by a low gambrel roof, while the staircase tower is accentuated by a low keel-shaped dome.
The monumental hall situated above the underground vaulted grit chamber area is one of the complex’s hubs. The hall’s roof has been built with angled steel trusses. Free-standing chimneys with decorated heads jut out symmetrically in front of the ends of both wings of the building. One of them was designed as a flue for boilers, and the other was a vent for the underground section. On the walls of the hall above the grit chamber vaults, there are several plates indicating that the floor has a maximum load-bearing capacity of 400 kg/m2. The façades were simply decorated, alternating smooth lightly-coloured plastered surfaces with brick facework. Solid stone cladding accentuates the entrances and plinths. The windows and doors are vaulted with the coordinated alternation of arches, segments and straight heads. A symmetrically positioned pair of elliptical windows is used to illuminate each of the entrances on the north façade.
The vaulted underground area is unique and is undoubtedly the most interesting architectural feature. The vaults in the underground part and, indeed, throughout the structure, are made of hard-baked brick facework. The curves of their geometric penetrations end in precisely rendered round fittings. A flattened vault transitioning into conches was used to arch the largest space, i.e. the impressively dimensioned grit chamber (12 x 28 m). Sewers A, B and C open into this area. The mouth of the sewers, which are ovoid in their cross-section, also ends in round fittings. A water wheel to turn the fan was originally installed by the left drain (marked A) and in the adjacent area. This piece of equipment did not remain in operation for long because the ventilation chimney benefited from a natural draft, so the unit was dismantled during the interwar First Republic. Light is directed into the grit chamber by circular glass-concrete skylights. Other underground areas, which consist of ten 80 m long sedimentation tanks and accessible via a separate entrance built on the north side of the building, are located away from the structure itself. The sedimentation tanks are, again, vaulted with brick vaults. The space here is interestingly designed – the oval ventilation openings in the brick vault change into the shape of a circle. The portals are made of strips of brick fittings. Two of the original four sludge wells can be found on the north side. A railway line was built along the northern façade to remove coarse dirt. The bridge connecting the left bank of the Vltava (on which the treatment plant and the underground tanks were built) with Císařský ostrov (Imperial Island) over the Podbaba Canal is a simple 3 m wide truss structure with a 34 m upper arch span that was installed on stone pillars of polygonal rubble masonry. Built in 1902, the bridge connected the treatment plant with sludge fields, dirt dumps and other operating facilities on Císařský ostrov. The original 700 mm narrow-gauge track has been preserved under the bituminous surface.
The Old Wastewater Treatment Plant in the Bubeneč district of Prague (building number 199) is a cultural monument entered in the Central List of Cultural Monuments of the Czech Republic under register number 11886/1-2148. The cultural monument consists of the main building (number 199), including its underground grit chamber and two chimneys, on Papírenská Street, the underground clarifiers, two sludge wells and their entrance, and the bridge of the former narrow-gauge railway used for sludge removal.
The complex is rounded off by the buildings of the chlorinating plant and screening chamber. In 2010, the cultural monument was declared a national cultural monument (except for the bridge of the former narrow-gauge railway) – see Government Regulation No 50/2010 of 8 February 2010. The bridge was declared a cultural monument under Decision No MK 9275/2010 of 14 June 2010.
In 2016, the complex became an anchor point of the ERIH (European Route of Industrial Heritage). In this tourist information network, it is one of rare example of early modern wastewater treatment in European cities deployed in response to the sanitary crisis.
The Old Wastewater Treatment Plant in Prague-Bubeneč, built in 1906, is a unique complex housing technical municipal equipment from the early 20th century. This functional whole, bringing together technological premises for mechanical wastewater treatment, the disposal of trapped solids, and technical facilities in structures of excellent quality, bears extraordinary testimony to the early days of wastewater treatment and the ecological approach taken to this issue. The site for the construction of the treatment plant and the elevation of the treatment process were selected and designed so that the water would flow according to the force of gravity.
All buildings and components, including technological equipment, have been reliably preserved and illustrate in full both the original operations and the outstanding structural and technical standard of wastewater treatment at the turn of the 20th century. The complex is an important milestone in the beginnings of the treatment process before the advent of biological and chemical forms of wastewater treatment.
The basic building material used in the Prague sewerage system and the wastewater treatment plant is the specially fired clinker brick, which is highly pressure resistant and waterproof. Specific shaped bricks were designed for the structure’s individual penetrations. The presentation of this complex contributes to our understanding of the standard of living and the circumstances behind the emergence and development of urban infrastructure.
The uniqueness of the Prague sewerage system does not lie in the actual drainage of foul water and rainwater from the city, as this was an issue being addressed by most European cities at the time. What makes it an advanced solution is that it incorporated a final mechanical cleaning station equipped with the latest technology.
The Old Wastewater Treatment Plant building is a piece of industrial architecture from the turn of the 20th century. Its outstanding value lies mainly in the technical equipment in the engine room, pumps, etc. These facilities have been preserved in their original form. They illustrate the technical progress that had been made at this developmental stage and the technology used in mechanical treatment. This was a key factor for the age of industrialisation and the emergence of modern cities. The authenticity of the exhibition is compounded by the ability to demonstrate the machinery and by the fact that the building functions as an industrial museum showing the history of sewerage. This includes its accessible underground area. Because it has been preserved so exceptionally, it provides a unique opportunity to understand sewerage system technology.
The Old Wastewater Treatment Plant has a partial system of masonry sewers, ovoid in their cross-section, with stone gutters. Sewers, together with the chambers, clarifiers, the clarifier gallery, the dome of the grit chamber, the water wheel chamber, etc., form a unique underground world. The trunk sewers directed sewage from the territory of Prague, some 5,418 ha in area, into the mechanical treatment plant.
Criterion (ii): The Old Wastewater Treatment Plant in Prague-Bubeneč is an exceptionally comprehensively preserved piece of the history of water management and urban infrastructure. It clearly illustrates our knowledge about the beginnings of a systematic solution for the drainage and disposal of wastewater in the city, and as a necessary means to ensure hygiene in the lives of its inhabitants and in the development of a modern city. It is a testament to the standard of technology and industrial architecture at the turn of the 20th century.
The Old Wastewater Treatment Plant uniquely represents the progressive idea of closing the water cycle of supply and sewerage. It illustrates an awareness of the need for the quality treatment of wastewater prior to discharge into the river. The design of this structure, as the last link in the chain of the city sewer network, testifies to the thoughtful drainage of a city in a way ensuring that its inhabitants enjoyed sanitary conditions while respecting the environment and respecting other users of the recipient into which the water was discharged.
Criterion (iv): The Old Wastewater Treatment Plant is an exceptional example of this specific type of water management structure that was being built in major European cities at the turn of the 20th century with the aim of increasing the quality of sanitary conditions for the life and development of the city and other users of water from the river recipient. The technology used in the treatment plant reveals a responsible approach to the environment already at a time of rapid urban development, when the idea of returning water used by man to nature in an environmentally friendly quality was not yet widespread. The preserved wastewater treatment technology and related machinery are a unique example of a well-thought-out functional whole, a completely preserved flow of technology situated in a structure of exceptional quality built in an impressive architectural design. The importance of this water management work is borne out by the actual composition and architectural rendering of the building, with the bold silhouette of its monumental hall.
The Old Wastewater Treatment Plant has survived to a high degree of authenticity. The existing surface and underground structures, together with the technological and technical equipment here, have been preserved in their original form. As such, they credibly document the situation when operations began in 1906 and include phases documenting the development of technology and technical treatment facilities in the period from 1906 to 1967. The Treatment Plant does not currently play the role for which it was originally designed. It has recently been replaced by modern treatment operations built in the immediate vicinity, a factor that also confirms how appropriate the choice of the original site was for the concentration of wastewater and the construction of a wastewater treatment plant in Prague. The fact that this monument was not upgraded, but was instead replaced by another functional unit, has helped to maintain its high authenticity inside and out. Likewise, the historical treatment plant was never converted to serve other purposes. Much of the technological equipment remains in working order and is exhibited as part of educational programmes. The steam engines and boilers from the time the Treatment Plant was first put into operation are still functional.
As the proposed site has been preserved to the full extent of its technological facilities and from the perspective of integrity, it has all the qualities necessary to express its outstanding universal value. It has been fully maintained as a functional unit that, in the flow of technology preserved here, unifies the individual processes intended to ensure the required purpose – to treat wastewater so that it is of such a quality that it does not degrade the recipient river. At the same time, it documents the process for the disposal of the solid material trapped here.
Structurally, the site and its technological equipment are a perfect example of an operational facility providing wastewater treatment processes and disposing of trapped pollutants. It fully encompasses all the processes needed to achieve the required purpose and represents the technical standard of those processes at the end of the 19th century and the beginning of the 20th century. It shows the level and development of sanitary engineering as a field of water management.
The significance of the technological complex has not been impaired by interventions stemming from the advancement of technological equipment and machinery during the operation of the plant (from 1906 to 1967) or by subsequent use. Even today, the Treatment Plant forms a tangible and materially complete complex. Viewed in its broader context, the treatment plant can still be perceived as a functional unit.
During the 19th century, the burgeoning population and expanding industry resulted in the serious deterioration of sanitary conditions in densely populated cities in the developing world. The solution to this sanitary crisis was to build modern infrastructure and prevent the spread of water-borne diseases. It was essential to supply drinking water and to systematically channel used water (wastewater) away from the populated area. The designs of modern systems also ushered in new types of buildings to accommodate them. The most important structures on water supply networks from the time of industrial expansion were water treatment plants (plants treating raw water to make it drinkable) and sewage networks comprising pumping stations and wastewater treatment plants (plants for purifying wastewater to such a quality that it would not harm the natural water into which it was discharged).
In the 1870s, the city of Prague itself began to address these problems. In addition to the quest for a quality source of drinking water, it was also necessary to ensure that used water was drained away. The existing sewer system did not have sufficient capacity and the sewers flowed directly into – and along the entire line of – the River Vltava. The polluted river water then infiltrated wells, endangering the health of Prague’s inhabitants and the population further downstream.
The system employed for Prague’s sewerage system and the Old Wastewater Treatment Plant in Prague-Bubeneč fits into the broad context of Lindley’s works (e.g. in Warsaw, Frankfurt, and Mannheim). This system is distinguished by:
No water management structures intended for the provision of infrastructure during the period of heavy industrialisation (water supply and sewerage networks and their facilities) have yet been inscribed on the World Heritage List. A more detailed comparative study of structures related to urban water management infrastructure was first prepared in 2018 by the TICCIH – the International Committee for the Conservation of Industrial Heritage (Thematic Study on the Water Industry as World Heritage, http://ticcih.org/wp-content/uploads/2018/05/TICCIH-Water-Report.pdf).
In 2019, a cultural site called the Water Management System of Augsburg was inscribed on the World Heritage List based on criteria (ii) and (iv). However, the value of this site is defined rather differently. The Augsburg site is presented as an example of a sustainable water management system that evolved over more than seven centuries on the strength of hydraulic engineering, and that drew on water resources beyond the scope of the river. The system in Augsburg does not have a wastewater treatment plant like the one in Bubeneč.
In the period relevant to the complex in Prague-Bubeneč (the late 19th century and the early 20th century), wastewater treatment was in its infancy. The solution for sewage disposal was to drain wastewater through the sewer systems to an area outside the city and to pump it into watercourses and seas untreated or, at most, after trapping larger floating objects prior to discharge.
Pumping stations that pumped wastewater for soil infiltration treatment have survived in Melbourne (the Spotswood Pumping Station; 1897), Australia, and in the brewery town of Burton upon Trent (Claymills Victorian Pumping Station; 1885), UK. The complete mechanical treatment of wastewater was included in a sewer system designed by W. H. Lindley for Frankfurt-Niederrad (1887), but only some of the clarifiers from this treatment plant have been preserved.
The Prague Old Wastewater Treatment Plant was the first modern municipal wastewater treatment plant in this area and is the only surviving representative of the history of wastewater treatment in today’s Czech Republic. The water underwent complete mechanical treatment (coarse screening, fine screening, grit and sand settlement, and sludge settlement) drawing on the gravitational flow.
By comparing the Old Wastewater Treatment Plant in Prague-Bubeneč with other monuments in the history of sewers, it is clear from previous comparative works that this monument is one of the few (if not the only) credibly preserved complete technological units anywhere in the world exemplifying the beginnings of the modern approach to wastewater treatment that involved treatment prior to discharge into nature. These aspects will be explored further in a more detailed comparative study in the nomination preparation process.