A neighbourhood containing the highest residential density in St. Helier, on the Island of Jersey, was suffering from a lack of open space. A 1.3 hectare site was identified as having potential to provide a new area of public open space; an idea conceived as early as 1996. A petition in 1997 gathered over 16,400 signatures supporting the idea. The challenge was how to create a water sensitive and sustainable design for a new park that balances environmental, technical and financial challenges.
Involvement of, and endorsement from, the public and the use of a multi-disciplinary project team were seen as being vital components of the project. In response to the Localism agenda, public consultation was to continue throughout the life of the scheme to result in a place which the community could feel to be their own.
The park was seen as an opportunity to bring immediate benefits to an area deprived of open space and demographically one of the poorest parts of Jersey. The transformation of the contaminated site into a park with trees and lawns could create a place for recreation and enjoyment and act as a catalyst for the regeneration of the surrounding area. A proposed scheme emerged after a robust site appraisal, establishing the relationship between the future park and the wider urban context.
Until 1991, the site was occupied by gas works and had since been used as a car park with any contamination sealed beneath tarmacadam surfacing. Development of the site required overcoming considerable problems associated with heavy contamination present in the ground. Jersey has no facility to treat contaminated material, so key features of the remediation were the re-use of existing site material and keeping spoil and wastage to a minimum for the scheme to become “Zero Waste”.
Two interactive water features placed at either end of the park – a water curtain and a water jet field provide visual interest and a community focus. All the water used for these features is being recycled at the central pump room and recirculated.
The remediation design provided a soil capping layer throughout the park. This capping layer is of varying depths to reflect the different planting depths required for the 150 new trees, the 10,000 new shrubs, and the lawns and dedicated biodiversity area provided at the eastern end of the site.
The capping layer consists of local soils and a drainage layer and below that an impermeable geosynthetic clay liner. The liner creates an impermeable barrier that prevents the mixing of capping material and the residual contaminated soil underneath. It also prevents the mixing of clean rain water and the contaminated ground below. The drainage layer above the impermeable barrier incorporates a bespoke drainage system that harvests the rainwater and channels it to an underground storage tank or alternatively discharges it to the public sewer system.
This 500,000 litre underground storage tank was constructed within the relined former tar well of the gas works. The stored water provides irrigation for the park via the site’s 5,400m of underground pipe work and over 6,000m of drip irrigation tube, watering grassed areas, trees and shrubs during the dry summer months.
It is hard to quantify and measure the ‘social returns’ of any scheme, but it is evident how this part of St. Helier has benefited immensely from a park which has rapidly become a focal point for celebrations and community events; the interactive water features are a draw for children and there are many using the park on a daily basis for relaxation. Its green and blue infrastructure has added considerable value to the local environment and biodiversity and therefore creates a valuable asset for all.
The case study demonstrates how a landscape-led multidisciplinary scheme can integrate land remediation, with sustainable construction techniques using Water Sensitive Urban Design principles to deliver a multi-functional landscape providing community benefit.
