Let nature do the work
Water and vegetation play a key role in Stockholm Royal Seaport. With well-thought-through design, blue and green structures fulfil several functions, contribute to synergy effects and deliver ecosystem services. This provides opportunities for recreation that contribute to better health and well-being.
2022 Highlight:
Multi-functional green infrastructure gains attention
There continues to be considerable interest among study visit groups and the media in learning about the experiences of Stockholm Royal Seaport's planning of water and greenery, for example, cloudburst management to handle heavy rainfall, and drought while simultaneously creating spaces for recreation.
Key figures:
- Approximately 140,000m² of new green space, which corresponds to roughly 20 football fields, has been created, including 26,400m² of green roofs, 47,300m² of courtyards, and 33,450m² of parks.
- 98% of the developers have achieved the .
- To date, around 600 new trees, including 20 different species, have been planted in public open space, of which 120 are oak trees.
Green structures where water and vegetation are actively used
Sweden's climate has become more unpredictable, with effects such as rising sea levels, heatwaves, and more extreme weather events increasing the risk of floods and droughts. These aspects are considered in the planning process. A stormwater strategy was developed already in 2011, outlining principles for stormwater management in Stockholm Royal Seaport. Stormwater is managed locally in an integrated system consisting of green roofs in conjunction with courtyards, parks, and green corridors featuring ponds and plant beds, as well as a delay and discharge requirement for block areas. All stormwater from public open spaces and excess water from block areas is directed via inlet wells to plant beds with pumice and biochar soil, which store and delay the water while ensuring good growth and directing surplus to recipients. The vegetated beds also help to purify the water.
During heavy rain, when the need is greatest, ponds and wet corridors capture water that would otherwise cause flooding. Parks and other green spaces can store large amounts of water. Two areas in the development have been identified where stormwater management is a challenge: Gasverket and Värtahamnen, which are flat, low-lying areas with hardened surfaces.
Greenery also contributes to pleasant environments for people to spend time in. In public open spaces, the greenery often consists of a combination of parks with meadows and green play areas, as well as vegetated beds containing a rich variety of plants. It also provides shade and lowers temperatures on hot days. A variety of plants ensures that trees and vegetation remain even if one of the species develops disease or rot. In Gasverket, greenery has been reduced due to the requirement to preserve the industrial character of the area.
To ensure that developers plan high-quality and multifunctional green solutions for courtyards and roofs, the planning tool ' ' is used. The size and shape of the courtyard, as well as how much walls and roofs can be used for vegetation, are important for determining the size of the eco-efficient area that can be created. Most developers achieve the Green Space Index, and the trend is that the social aspect plays an increasingly important role by using roofs as social spaces. An important result is that the work with the index has led to the requirement being included in the city's land allocations. A guidance document and calculation template are available for all developers.
Interest remains high in learning about the functionality of plant beds for managing stormwater. Before large-scale implementation takes place in Stockholm, the function, i.e, delay and purification capacity, is evaluated. A multi-year evaluation project is also planned.
Natural values and dispersal zones
The Royal National City Park has one of the Nordic region’s largest contiguous connections of oak trees with high nature values and particularly protected trees. The park is home to plants, animals and insects that are conservation species, some of which are listed as endangered or protected under the Species Protection Ordinance.
As urbanisation and densification increases, green spaces and corridors play an important ecological function as dispersal corridors to strengthen natural values. The location of Stockholm Royal Seaport between the northern and southern parts of the park is crucial for linking them together. The green structure plays a major role as part of a dispersal network for oak-living species and amphibians. Important habitats are conserved and strengthened through planting and the construction of wetlands and hibernation sites. New green areas are strategically placed to create dispersal zones, while old oaks are preserved and new ones planted in the corridors. In one of the park's green corridors, there is a frog tunnel that connects to moisture corridors and ponds.
An ecological survey previously conducted identified that protected water salamanders lived in a pond near the oil depts in Loudden. Prior to the remediation of the land, they were captured and relocated to a newly constructed pond nearby. The rare and protected narrow-leaved lungwort has also been given a new habitat on the roofs of the terminal building and at the Bergianska Garden. It will be replanted as soon as the land remediation is completed. Other endangered species in the area include the Eurasian eagle-owl, herring gull, lesser black-backed gull, and the great capricorn beetle.
To monitor the function of the green corridors and green roofs as dispersal zones, an insect study has been conducted in Hjorthagen. A large preserved oak was important for dispersal, while flowers and moisture corridors were important for flower-seeking species. The green roofs contributed marginally to attracting insects. The inventory provided valuable information for planning future phases of the development and other parts of the city.
Improved water quality and bottom sediment
Lilla Värtan is located between Stockholm and Lidingö and forms Stockholm Royal Seaport’s waterline from Husarviken to Loudden. Levels of phosphorus and nitrogen in the area are high, as are amounts of metals in bottom sediments due to previous historical industrial activity.
An early investigation of Husarviken’s contaminated bottom sediment determined that the sediment would not be remediated to avoid the release of dangerous heavy metals. Access to the water is limited by jetties from which it is not possible to swim.
In conjunction with the detailed development plans for Kolkajen and Ropsten, marine biological investigations have been conducted in Lilla Värtan. These show that the presence of benthic animals, plants and fish is very limited.
The environmental impact assessment states that remediation in the water area due to urban development in the long term contributes to reduced pollution and improved surface water quality in Husarviken and Lilla Värtan. Among other things, the goals of living coast and archipelago and a rich flora and fauna will be achieved. Improvement of water quality is also made through, for example, discharge requirements for drainage-pump water.
Investigations in Saltkajen in Värtahamnen show that soil, sediment and groundwater are polluted, but the concentrations are moderate and lower than in the nearby areas. The overall assessment is that there is no need to implement follow-up measures to alleviate environmental and health risks.
Key events in 2022
- A stormwater tunnel in Värtahamnen was completed.
- 16 new trees were planted and 115 temporary planter boxes were installed, and the local library organised an event for residents to exchange plant cuttings.
- About 40 bird and debris nest boxes were installed.
- A basis for evaluating the function of plant beds regarding delay and purification capacity was developed.
- Several soil remediation contracts have been ongoing.
2019 Swedish Architects’ Landscape Prize
Stockholm Royal Seaport is a model for how vegetation and water can be used in urban planning, something that was acknowledged by the 2019 Swedish Architects’ Landscape Prize and in media.
Achievements for 4. Let nature do the work
4.1 Use ecosystem services
98% property developers fulfil GSI.
Approximately 140,000m² of new green space have been completed, including: 26,400m² green roofs 47,300m² courtyards 33,450m² of park space which correspond to 11m² per dwelling. 15,000m² street vegetation and rain gardens
630 new trees have been planted, of which over 120 oaks on public land, consisting of around 20 different tree species.
1,600 water salamanders have been moved from a pond at the oil tanks in Loudden to a new pond at Kaknästornet.(2020)
The resident survey shows that 68% are satisfied with the outdoor environment in their courtyards. 87% are satisfied with the outdoor environment in the area and that 84% visit parks and nature areas daily or several times a week. (2019)