Corniche des Forts Park by Ilex Paysages

The Corniche des Forts Park is set within a network of parks that stretches over a 3 km long hillside of the French plain, in the towns of Lilas, Romainville, Pantin and Noisy-le-Sec, in the East of Paris.

For safety reasons due to the presence of many underground galleries, this former gypsium quarry was closed to the public. Over the years, a lush vegetation colonised the site while urban pressure in the East of Paris caused massive densification with limited access to greenspaces. Reinvested by a resurgent nature, the site, referred to as “the forest” or “the jungle” by residents, has become the centre of all attention and the symbol of a pressing need for nature.

In this context, the Corniche des Forts Park, inaugurated in May 2021, became a 25 hectares Nature-Park, composed of a 20 hectares non-accessible sanctuary for the existing vegetation, surrounded by a 5 hectares promenade open to the public, bypassing the central forest, overlooking it, letting the ecosystem of the renatured quarry live, while highlighting it and providing leisure facilities to the community.

Nature preservation, discovery and leisure

The landscaping of the park creates 5 hectares of open space, with the observation ring occasionally growing to accommodate platforms for leisure and sporting activities on the edge of the protected area. These include leisure activities accessible to the public for everyday use (cycling, running…) but also sporting activities with light equipment (sport apparatus, playgrounds, a 26-metre long outdoor climbing wall…), and resting areas. In the future, a pony club and a treetop adventure park may be added to the park.

Meanwhile, the park’s pathways are conducive to nature observation, with bird-watching in particular, and raise public awareness on the issue of biodiversity in dense urban environment, with outdoor information panels and carefully crafted viewpoints.

To adapt to the existing fluctuating topography, a bespoke 124.70 metre long and 3 m large footbridge punctuates the walk and brings pedestrians closer to the forest as it stands 6,50 to 8,50 metres high. Observation huts are nested above the three pillars of the footbridge, as invitations for contemplation and discovery.

The project was nominated for the 39th Equerre d’Argent Prize 2021 under the Public Space and Landscaping category, together with Friche Belle de Mai in Marseille (winner, Kristell Filotico and Atelier Roberta), Parc des Ateliers in Arles (Bas Smets), Martin Luther King Park in Paris XVIIe (Osty & Associés and François Grether).

A natural system of parks of public interest

The park creates a network of greenspaces that connects the Fort of Noisy and the Fort of Romainville through the Park of Heights (Parc des Hauteurs), between the Henri Barbusse Park and Romainville’s communal park, reinforcing an ecological corridor in a dense urban fabric. For safety reasons due to ancient underground quarries present on site, the central area in Romainville is the only non-accessible part of this system of parks. It is transformed into a nature sanctuary around which paths and leisure facilities are open to the public, offering 5 hectares of outdoor area for the local community.

Balancing biodiversity protection and public accessibility

The project had to navigate between opening up the site and protecting it, both due to the risks caused by the underground galleries and to protect its rich and unique ecosystems. We chose to embrace the technical imperatives and integrate them at the core of the project’s concept.

Thus, forest clearance was limited to the bare minimum and to specific sectors, on the edges of sites of ecological importance, making the project develop around these nature sanctuaries. Moreover, the balance between backfilling and filling materials also played a big part in determining the sectors to develop and those to safeguard. The preservation of the existing wooded edges, as well as a new landscape structure (alternating between open environments with a predominance of grass, semi-open and closed environments with trees) will encourage the development of a greater diversity of species within the Corniche des Forts.

Strict environmental monitoring was carried out for the full duration of the project by an ecologist to ensure the design keeps clear from areas of floral and faunistic interests. Compensatory measures were put in place, before, during and after construction, such as the implementation of temporary habitats prior to constructions works.

The Corniche des Forts Park was a 25 hectares wide unstable brownfield site, and is today transformed into:

a 20 hectares wide sanctuary for the existing ecosystem, constituting an open-air laboratory for sterile soil recovery,
and 5 hectares of stabilised biodiversity-supplemented grounds open to the public, with leisure facilities.

Safety and flexibility: adaptation to technical challenges

On this former 25 hectares wide unstable brownfield site, the municipality had to deal with a diversity of challenges, including securing this dangerous site from risks of collapsing, preserving the resurgent ecosystem, dealing with the community’s frustration caused by the inaccessibility of this large open space (and potential unsafe behaviours like intrusions).

To secure the site, three aspects were taken into account:

backfilling: to minimise the input of external materials causing disturbance and with regards to the circular economy, the goal was to use most of the backfilling materials from the site;
retaining walls: to secure unstable mounds and transform them with 3 to 1 slope gradients, retaining walls from 0 to 7 metres had to be put in place. Gabion retaining walls filled with stones seemed the best fit considering their ability to accommodate potential shocks coming from the underground cavities;
rainwater management: to prevent water dripping into gypsium layers and causing soil to collapse, rainwater management was an essential aspect to consider to ensure the park’s stability. Rainwater is thus collected through swales, pools, drainage of the retaining walls…

Due to the special nature of the subsoil and its many cavities, all technical solutions had to be able to withstand slight deformations, and be fully integrated with the aesthetics of the park, with soft curves and incremental replacements.

After 50 years of stress inflicted on this industrial site, the ecosystem will need time to heal. The project thus integrates flexibility as a core value, proposing spaces capable of welcoming, now and later, a variety of uses and activities, in constant evolution.