Innovative stormwater management approach takes advantage of synergistic opportunities

Location: Frederiksberg, City of Copenhagen, Denmark

Population: 105,037

Climate: Baltic

Duration: N/A (recently)

Sector: Water efficiency

Funding sources: Public

City networks: C40

Savings: Frederiksberg’s strategic approach combines projects with scheduled construction and reduces tree maintenance with rainwater catchments to save money;

Solutions: Frederiksberg is leading the way in developing bespoke stormwater management projects that fit within the city’s dense street structure.

Multiple benefits: Social, health, economic and environmental co-benefits.

Objective – To undertake a co-creation process to create new and innovative solutions.

Solutions – Frederiksberg is trying out a new style of tendering in which the city and suppliers collaborate to develop new and innovative solutions. For example, the city is creating stormwater catchments that irrigate urban trees, minimizing the need for manual watering while sparing sewers during heavy rainstorms. The city wants to pair all-new urban trees with integrated rainwater management, where water is collected in subsurface basins and used to hydrate trees during dry months. Nine sites are now intended to manage up to 1,295 cubic meters of stormwater, with plans to expand the project around the city.

The city also took advantage of adding stormwater reservoirs beneath the building and nearby roadways, which will protect the area from run-off and reduce combined sewer overflow. The project involved renovating Langelands Plads, the city’s public square, to manage stormwater and safeguard the neighbourhood from flooding surpassing a 100-year rainfall event. Furthermore, the city is establishing various stormwater management programs in conjunction with construction projects and natural infrastructure, which will act as a test platform for projects that will be scaled up across Denmark.

Funding – Through public tendering process.

Innovation – The readiness of the city to engage in a co-development process with private firms results in innovative solutions. Even though this is an unconventional strategy, the city has discovered that it saves time and money while improving infrastructure solutions.

Success factors – 1) Tailor technology to the city’s needs: All too frequently, new technology is thrown into projects at random. Langelands Plads’ digital control system is adapted to management demands rather than a technological push, resulting in a lean, reproducible, integrated system that saves the city money. 2) Collaborate across departments: Frederiksberg is breaking down departmental silos to identify new opportunities. Collaboration across multiple city departments is used to develop, maintain, and fund a plan for coupling torrential rain projects and urban trees.

Significant outcomes

• Preventative stormwater management should lower future flooding costs. Moreover, stormwater catchment combined with urban trees across the city, which is expected to be integrated over the next 20 years, could handle 31.3K cubic meters of water.
• Stormwater infrastructure decreases the chance of combined sewer overflows, which can pollute the sea. The initiatives also lessen flood risk in downstream areas.

Synergies with local policies:

• Frederiksberg’s climate plan. By 2030, Frederiksberg intends to be CO2-neutral. The climate plan calls for the building of cloudburst projects capable of containing 250,000 m3 of rainwater and protecting the city from flooding;
• Copenhagen Climate Adaptation Plan. By 2025, Copenhagen will be the world’s first carbon-neutral capital. The municipality’s climate adaptation work must encourage integrated city and infrastructure development to benefit the inhabitants and the environment. For instance, integrated green space development reduces heating, manages stormwater, and increases recreational opportunities.

Political alignment:

• Danish strategy for adaptation to a changing climate. The government’s approach emphasizes the importance of national adaptation to climate change. The strategy’s purpose is that in the future, climate change should be recognized and integrated into planning and development in the most appropriate way possible, including actions related to water supply;
• Action plan for a climate-proof Denmark. The Action plan entitled “How to manage cloudburst and rainwater. Action plan for a climate-proof Denmark” became available in 2012. It gives an overview of the government’s actions to ensure that Denmark is more resilient to climate change, whether planned or already underway (source).

Marketability: Through the replicability of a stormwater management system that fits the city needs.