Turenscape transforms a brown field in Bangkok into Urban Nature

Turenscape transforms a former tobacco factory site into a green space that regulates storm-water, cleanses contaminated water and provides habitats for wildlife.

Project: Benjakitti Forest Park

Location:
Thailand

Architects:
Turenscape

Typology:
Adaptive Reuse, Landscape and Gardens

Area: 102 acres

Year: 2024

Beijing-based Turenscape’s Benjakitti Forest Park has become a new cultural icon for Thailand’s capital city, Bangkok. Working on a limited budget and short timeline, Turenscape redesigned the former tobacco factory into a ‘green lung’ that regulates stormwater, cleanses contaminated water, provides habitats for wildlife. The green spaces has become the largest public space for the dense population. With a modular approach to earthworks practice, the project showcases a replicable method, transforming the existing concrete ground into a resilient living ecosystem.

Located in the Chao Phraya River delta, Bangkok has an avergae elevation of 1.5 meters (4 ft. 11 in.), or lower than sea level. Most of the area was originally swampland, which was gradually drained and irrigated for agriculture through the construction of canals. Subsidence has been a major problem, caused by extensive groundwater pumping, which together with global warming has resulted in increased flood risk due to its low elevation and inadequate drainage infrastructure. Heavy downpours often resulted in urban runoff that overwhelmed drainage systems and caused severe flooding affecting much of the city.

The project site is 102 acres and located in Khonti District, in the heart of Bangkok, is surrounded by Phaisingto Canal to the north, which was contaminated with urban runoffs and sewage. To the west of the site is the Duang Phithak Urban Expressway, separating it from the adjacent community. To the east is an artificial lake, a rehabilitation hospital and a hotel and the Queen Sirikit National Convention Centre to the south. The former tobacco factory that had single floor warehouse buildings scattered in between a number of canopy trees. The budget of the project was limited to only 20 US dollars per square meter and it was expected to be finished in a very short period of 18 months. The project was overseen by the army. The design was the result of an international competition.

Design objectives and strategies

The project was mainly intended to be a designed as a central park that provides a big green space in the heart of the city, providing holistic ecosystem services, including storm-water regulation to adapt to the changing monsoon climate. It was also intended to demonstrate a nature-based solution to cleansing ubiquitously polluted urban water, life supporting for native species, and also as a public space badly needed for daily recreational activities and other cultural services. Recycling and reusing, creating porosity and wetlands, initiating a low maintenance natural environment, and creating immersive people spaces were the main strategies.

Firstly, cut-and-fill is used to create wetlands dotted with islets. Abiding to the essence of their approach, all the existing trees on the site were preserved and integrated in the design. The sports center and museum that were the two programs to be added to the project, were designed using the existing buildings. The demolished concrete materials are set to be recycled for the earthwork foundation and paving.

This process gives rise to three distinct wetlands, each adorned with hundreds of miniature islands. By meticulously redistributing the earth without importing or exporting any soil, these wetlands emerge, transforming the rigid landscape into a spongy, porous haven.

During the monsoon season, this newly crafted terrain can retain up to 200,000 cubic meters of storm-water from the surrounding area. As the rains subside, the previously hard clay surface morphs into a moist, sponge-like habitat, fostering a rich community of native plants and animals. Remarkably, this transformation requires minimal irrigation and maintenance during the dry season.

The beauty of this modular landscape lies in its simplicity and efficiency. A single digger can execute the entire process, reducing reliance on skilled labor and making large-scale operations feasible. Through this innovative approach, a once inhospitable environment becomes a thriving, self-sustaining ecosystem.

The foundation and foot of each islet are strengthened using recycled concrete materials, ensuring sustainability and durability. At the center of these islands, pre-existing trees are preserved, while young seedlings of canopy trees are planted on newly constructed mounds at minimal cost. These vibrant additions create a harmonious blend of old and new growth.

The wetlands are ingeniously designed at two elevations: a deeper core area and a terraced shallow shoreline. The shoreline connects to a linear water-remediating wetland along the park’s north and west borders. This system filters contaminated canal water, cleansing 8,152 cubic meters daily, elevating water quality from the poorest V grade to III grade. This purified water sustains the wetlands during dry seasons, transforming the shallow shoreline into a thriving ecotone that fosters lush vegetation communities.

In terms of infrastructure, major roads are preserved and repurposed with a thoughtful twist. A leaner cut is made in the middle of the pavement to create a permeable bio-swale and flower bed, effectively separating bicycle lanes and pedestrian paths. This intervention scales down the wide truck road to a more human-friendly dimension.

For the sports center and museum utilizing existing buildings, the principle of porosity is applied. Portions of the factory building roofs are daylighted, allowing natural light to penetrate and the living landscape to integrate with the extensive concrete structure. This transformation breathes life into the built environment, merging nature with urban functionality.

The evolution of a semi-natural plant community begins with seed sowing and tree seedlings, set against a modulated landform featuring a diverse micro-environment. This process fosters low-maintenance vegetation that will be continually and spontaneously enriched by native species. As a result, a symbiotic ecological interrelationship is expected to develop between fauna and flora. The constructed wetland, with its inherent messiness, introduces a new aesthetic of dynamism and diversity, standing in stark contrast to the typical urban landscape.

Multiple boardwalks are designed along the shallow wetland at the edge that provide visitors with an immersive experience of urban nature. A sky walk runs through the preserved canopy trees and connects the park, previously separated by major roads, to create a unique immersive experience through the tropical foliage.