Tainan Spring urban park breathes fresh air into a congested city

In an act of imaginative re-purposing that takes account of the changing nature of how we shop, the city of Tainan in south west Taiwan has curiously chosen to reduce rather than add to its retail offering. Architect MVRDV has made a significant new public space in the centre of this highly congested city, known as Fort Zeelandia when the Dutch East India Company controlled it in the 17th century. A Dutchman himself, MVRDV partner Winy Maas says he was humbled to be declared winner of a city government competition – set by the former mayor, now Taiwan’s vice president – to rejuvenate the urban area east of the old canal harbour.

Named Tainan Spring, the €4.7 million built proposal has created a 1.5ha public water park in the centre of the city, an ‘urban lagoon’ which replaces a defunct shopping mall that previously stepped from 4-12 storeys along its 180m length and 45m width. Maas explains that the city wanted to deal with an urban block thathad suffered due to the consumer move to online retailing, and was looking to architects to reinvent the space. MVRDV responded to the modern history of the site as well as its distant past not only by celebrating the water aspect of the former harbourside but by also acknowledging the ‘removal’ of the retail mall itself.

The park is one of three interventions being conducted by MVRDV in the city. To its east the project has just completed a landscaping proposition along the main Haian Rd, which replaces a lane each side of the contraflow with urban ‘wilding’. Under this, lush greenery from the surrounding jungle was planted along a 1km length to mask ventilation shafts from a massive car park below. And in another act of radical greening it will soon complete a market hall whose roof surface will be a commercial garden.

But here it’s all about the water. In an almost post-apocalyptic envisioning, the practice has deconstructed the mall down to its basement level car park and installed inside it an undulating lagoon landscape, which can be gradually ‘flooded’ according to the season. Forming the islets are hillocks where local trees transplanted from the jungle grow and flourish in the new pool area. Yet this greening is read against the background of the remains of the mall, whose concrete structure looms like a modern ruin over the plaza.

But, as Maas explains, that act of removal is something of a sleight of hand, as the design of the new plaza had to be modified by the proximity of the saline canal that leads out to the city’s new port area. ‘The west end of the plaza actually forms part of the retaining wall of the canal, so there were knock-on effects,’ he explains.‘In Holland we are used to the fact that sea water runs beneath the foundations of our buildings and the same was true here; so in deconstructing the building, we had to deal with resultant hydrostatic pressures.’ So while the mall’s two basement parking levels were retained, with B1 now forming the new lagoon level, the removal of 80% of the building’s original mass necessitated weight compensation in what remained to ensure groundwater didn’t cause upthrust in the retained slabs. It meant a strategy of demolishing the building piecemeal. Maas adds that this involved removing the steel for recycling after the concrete around it had been scabbled away. ‘It was a beautiful act of removal and relocation, one done by hand to balance the load on the site by gradually moving the rubble down into the lower basement at level B2.’ As if to mark the process, the firm
even installed a glass floor at B1 level so users can see its final resting place.

Visible on the same level on north and south sides are the requisite water storage tanks and ozone filtration plant. Two sets of these were specified to ensure that if return water contaminates any one of the 180m3 tanks, another can be brought into service. Water enters the lagoon via two floor-set inlets, with return water outlets on the perimeter of the B1 plaza floor. As part of the maintenance regime, the lagoon is completely emptied every Tuesday to allow for a ‘deep clean’ of the water and the plaza floor.

Numerous factors governed the fluid dynamics of the plaza, says Maas. First was the need always to keep water flowing. Mosquitoes abound in Taiwan and dengue fever is a real concern, so there could be no areas where water could pool and allow the insects to lay eggs. Second was the ability to take account of seasonal changes in the rainfall. Water levels are adjusted according to demand with mains water when necessary but generally during the monsoon season they will be higher, at 70cm, and in the dry summer months will be lower, at 30cm.

Water misters set into concrete hillocks in the lagoon help to generate a localised climate. In a city where summer temperatures regularly hit mid-30°C, they can lower the ambient temperature at lagoon level by 5-8° when activated.The mist performs a secondary function too, contributing to net evaporation levels. The upward movement of air and moisture helps prevent exhaust fumes and detritus from the roads above and around from sumping at lagoon level; the effect, claims Maas, is palpable: ‘The sunken pool is cleaner than the grass park area we’ve installed at ground level – though we are hoping that in the long run electric cars will deal with the issue altogether.’

Surface evaporation from the pool is mitigated by many indigenous trees – Palaquium formosanum, Terminalia catapa and Plumeria.Planted in tree pits set into the hillocks, they are accessed for tending by one of the four full-time gardeners during the weekly maintenance. The floor of the lagoon is formed of resin-bound fine pebbles, which offers a good non-slip surface for feet as well as an easy cleaning regime. Being open to the public 24 hours day – ‘it’s even busy past midnight’ – meant MVRDV also had to consider the lighting of the scheme. It adopted a delicate approach – lighting, not directly but discreetly, the remaining concrete structure or  the individual planting growing out of the lagoon floor, as well as the floor itself. The section of lagoon beneath the road is a sublime space when lit by night, believes Maas, even though the city’s sewers run above your head there, set in concrete trenches accessed from road level.

How to deal with the perimeter areas that bound the lagoon remains a work in progress, but Maas thinks the idea is certainly not to run it through with retail units, as ‘Asian cities have [far more] shopping areas than European cities and generally it’s hard to find somewhere where you can’t shop’. Instead the aim is to allow the ruined structure to be ‘occupied’ with new uses over time; to give these, like the plaza itself, a public purpose. A tea house has already been established there and there are plans for a small library, while both organised and impromptu concerts have taken advantage of the good natural acoustics. The architects see this is very much a programme in development.

It might be an unsettling thought to reference Tarkovsky’s bleak post-apocalyptic 1979 thriller ‘Stalker’ as an influence on your design, but Maas says the half-flooded, abandoned chemical factories that served as the set for some of his scenes, have in a sense, been re-envisioned in a sunnier and certainly less toxic environment. Yet seen in the light of the recent economic chaos brought on by the coronavirus global pandemic, perhaps it is a portent of a dystopian future. Or, in its sublimity, perhaps Tainan Spring can merely be read as a ‘modern ruin’ that picks up where critical US art/architecture practice SITE left off; which if so, suggests a happier ending for the death of the high street. You decide.