This Master’s Thesis addresses the urban infrastructure of water as a medium connecting nature, the society and technology. Infrastructure is understood as a socio-technical system and a shared platform for interaction between objects. Water is the core infrastructure for human life, and moreover, the infrastructure for transporting and treating water forms the foundation of urban settlement. Yet the development of infrastructural systems has removed the experience of water from the urban realm, and produced an ever-expanding but invisible maintenance network sustaining everyday life – the hidden city.
The theoretical framework for the thesis is the discourse of landscape urbanism that has been prominent in the fields of landscape architecture and urban studies in recent decades. Through contributions from international authors in architecture, landscape architecture, geography and urban planning, the thesis aims at articulating an interdisciplinary understanding of the contemporary urban context, based on the concepts addressed by the aforementioned fields. The focus is on establishing an integrated design approach towards the city, concerned less with traditional boundaries of profession, and more in the potential opening up of new methodologies, narratives, and sites for spatial exploration.
The infrastructure of water is studied from a historical perspective in the context of urban networks, and in a case study of Ancient Rome. Roman infrastructures display an example of a water system serving both the functional purposes of water sustaining the city, and the social aspects of experiencing water in the public realm. To establish a local context, the development of water systems in Finland is introduced, including a study of the water tower as an architectural type operating in the water supply network. The research focuses in Helsinki, as it forms the only multi-node urban region in Finland, and thus the organization of its infrastructural networks is substantial to the study of Finnish waterworks, both in the past and today.
Finally, the research is applied in a design project negotiating the interfaces between infrastructure, architecture and landscape within the local condition of the Helsinki water supply system. The project site in Lauttasaari is an infrastructural landscape in transition, as the decommissioned water tower on Kotkavuori is set to be demolished despite calls for preservation. The thesis project addresses the qualities of infrastructure as part of the collective memory of a place, and seeks to uncover its potential in enriching the experience of urban realm. The project is an exploration of a water treatment environment as a place of recreation, integrating the hidden city to the landscape of everyday.
By applying techniques of green infrastructure to the remains of the existing but disused water supply structures, and flipping the purpose from supplying pure water to purifying grey water on site, the project seeks to challenge the way wastewater is perceived and treated in the contemporary society. Instead of all water going down the drain, the water supply system could become more sustainable and more efficient by recognising the potential to reclaim and reuse most of urban wastewater volumes. In the thesis project, low-polluted grey water from homes in the neighborhood is diverted to the hill of Kotkavuori, and treated in a sequence of steps forming a recreational path down the slope to the seaside. Finally, the purified water is released into the Baltic sea via outdoor sea baths, inviting citizens to experience and interact with the water, and to renegotiate the boundary between manmade and natural, the hidden city and public space, and infrastructure and landscape.
This Master’s thesis is completed as part of the Master’s Programme in Architecture at Aalto University School of Arts, Design and Architecture, Department of Architecture.
Supervisor: Professor Hannu Huttunen, Aalto University School of Arts, Design and Architecture
Instructor: Frances Hsu, Ph.D., Aalto University School of Arts, Design and Architecture
Helsinki Region Environmental Services Authority (HSY) manages the water supply and wastewater systems of over 1 million people. Raw water to the Metropolitan area is transported from Lake Päijänne 120 km away in an underground tunnel, and purified for consumption at two water treatment plants in Helsinki. The process is linear: raw water in, wastewater out. While the processes to compost sludge from wastewater into agricultural products, wastewater heat recovery and biogas production are highly developed, the system is founded on an abundance of high quality raw water, and no water reuse or different levels of water treatment "fit for purpose" are integrated.
Water towers have two purposes: first, they store large volumes of water to even out consumption peaks and for emergencies, such as large fires. Second, they pressurize the water supply network so that users get their water delivered by gravity. For this reason water towers are located on the highest points of the landscape. Moreover, the system is enabled by the relatively uniform and low building heights in Helsinki.
The diagram shows the population of Helsinki, volume of water consumption per capita, and superimposed a timeline of water tower construction. Helsinki urbanized rapidly in the 1960–70s, visible in the cluster of water towers from that era.
In recent decades, water usage has decreased due to new technologies and water-saving appliances, and several water towers have been decommissioned from the waterworks. However, none have been reprogrammed for a new purpose, and mostly the disused structures stand as empty landmarks. The water tower of Vuosaari was demolished in 2005, and the same fate awaits the Lauttasaari tower in late 2015.
In the undeground realm of flows and networks, Lauttasaari is not an island. An interconnected web of pipes, mains, tunnels and rails, violently drilled into the ground, maintains the world above the surface. Water towers connect the city-wide underground network to the landscape, and thus, they are operational landmarks of the uninhabited Helsinki; of the urban metabolism.
Set for demolition in December 2015.
The Helsinki City Planning Department published an ambitious city plan draft in November 2014, targeting the expected population growth and the lack of affordable housing by proposing new sites for in-fill development. A key mechanism in the draft is the "bulevardization" of inner-city highways, including Länsiväylä which currently cuts through Lauttasaari, causing noise and pollution, as well as large residual zones. In the City plan vision for 2050, the population of Lauttasaari could be nearly doubled by radically urbanizing the northern part of the neighborhood.
Today, the residential typology of Lauttasaari is segregated into two scales: small scale housing close to the sea, and multi-storey residential buildings mostly inland. The separation of lifestyles and demographics is negotiated in the public realm that has historically focused on recreation. The seaside is appropriated through a public recreational trail around the island, along which a variety of outdoor activities take place. However, a large part of the facilities is not accessible to the public, from fenced-off boat berths to a members-only sauna club, representing a discreet privatization of the sea shore.
Kotkavuori area on the north-eastern side of Lauttasaari is less well-serviced in terms of recreational places than other parts of the island. There are few facilities, and the park of Kotkavuori with the water tower is underused as a green space. When the water tower is demolished in late 2015, the site can be rediscovered within the local context. The steep topography of the hill creates a boundary condition, and the recreational path is less popular in the north than in the southern shore with all the adjacent activities. By reintegrating Kotkavuori into the urban recreational landscape of Lauttasaari, the thesis project aims at negotiating between the future urbanization and the role of recreation as a common ground for all locals.
Lauttasaari water tower in black.
The project site becomes a sequence of water, beginning where our daily experience of water normally ends: at home. As water from showers and kitchen taps goes down the drain, it is diverted to Kotkavuori utilizing the existing tunnels that used to supply water when the water tower was still functional. The flow of water is reversed in recognition of the change in the landscape brought about by the demolition of the water tower. Moreover, the reclaimed water is seen as a resource, not as waste.
An underground space of the tower carved into the rock of Kotkavuori is transformed into a settling tank, the first step of treating grey water from nearby homes. Organic matter floats to the bottom of the tank, and the water is lead to the filtration trail downhill. Upon reaching the seashore, the water is released into a landscape of pools as an invitation to interact with the water. The pools overflow into the sea as water outlet is as constant as domestic water consumption. As an interface where the previously infrastructural, and now recreational, water and the sea water merge, floating treatment wetlands create platforms to occupy while purifying the europhicated Baltic Sea with a concentrated wetland effect.
Grey water purification in a linear sequence down Kotkavuori integrates a recreational path to water treatment by sand filtration. The path route is defined by the parameters of existing topography and a continuous 0.5...1 % slope necessary for the water flow.
Biomimic floating treatment wetlands remove ammonium, nitrate, phosphorus, organic carbon and suspended solids from the sea water, while creating platforms to occupy for recreational activities. The floating treatment wetland concept is applied from the BioHaven technology.
The site of the demolished water tower becomes an open space inviting appropriation. A designed ruin, the place is transformed into an amphitheater by carving steps for seating into the manmade plateau at the apex. The elevated platform on top of the underground settling tank functions as a stage for events.
The seaside is transformed into a landscape of recreation: a series of pools attract visitors to interact with water in the urban landscape. The baths are linked to the old shoreline, and get deeper the further away from the shore one gets, while defining a new occupiable boundary between land and sea. The floating islands and the pier offer further opportunities to observe the interplay of water as infrastructure and water as recreation.
The proposed pool landscape is an outdoor bath type mediating between a constructed outdoor swimming facility and a beach by natural water.