Odense: Rubbish tip transformed into an oasis

Much has happened on Stige Ø since Odense Municipal Council began the transformation from a rubbish tip to a recreational oasis for the inhabitants of Denmark's third-largest city in 1994. A metre-thick layer of earth was spread across the entire island to limit pollution from the area. Despite the fact that the buried rubbish still impacts on the environment, Odense Municipal Council has succeeded in creating an area of natural beauty with a lot of potential for physical activity. The island's users can take a stroll or go Nordic walking, mountain biking tracks have been established, as have facilities for canoeing and kayaking.

In the summer of 2005, Odense Municipal Council arranged a competition for the further transformation of Stige Ø into a recreational area. The winning proposal has since become a feasibility study for Stige Ø. The long-term objective is for the area to provide facilities for both physical activity and reflection. Nine 'activity bases' will enable the Odenseaners to get exercise through play, stargazing, freestyle events or swimming in a bathing lake. The Read Houses at the harbour provides users with shelter or somewhere to store equipment, while the former meeting hall, the Green Hall, facilitates indoor activities.

The activity bases are surrounded by three-metre high grassed embankments. The area designated for 'immersion and reflection' consists of so-called biotope strips, green areas that form a habitat for specific species of fauna and flora. There will also be facilities for nature related activities. The biotope strips help to reinforce the island's natural terrain as well as developing its natural biotope and helping to establish new ones.

For a 1967 to 1994, the island functioned as the city’s rubbish tip, although it had already been used for many years as a recreational area for the inhabitants. The rubbish tip was established on condition that as soon as it was no longer used it would be converted back into a recreational area. Some 10,000,000 m³ of trash were tipped on Stige Ø during its time as a rubbish tip, for example industrial waste, construction waste and bulky waste.

Today, the remains of this waste lie beneath a metre-thick layer of soil. This gives rise to undesirable percolation when rainwater seeps down through the deposited waste (read more about percolation under the heading 'Other facts'). In several locations across the island, percolation wells have been installed in which they percolated fluids are collected and filtered before passing into the public sewage system. Deep ditches have also been dug in the island's undulating landscape to collect surface water and prevent percolation. On the positive side, decomposition of the waste produces gas which is burned by Odense's households. Gas pipes, percolation wells and deep ditches form part of the green island's landscape - bearing witness to its past as a rubbish tip.

Energy rises out of the rubbish
 

The gas produced as the waste decomposes is exploited by means of a gas installation. First, the gas is treated in four containers on the hills of Stige Ø. From here the gas is sent by a system of pipes to a combined heat and power plant on Lind Hansen’s Vej in the city.

In 2002, nearly 5,000 households were supplied with all their electricity and some 900 households had their heating requirements covered. It is estimated that in 2006, Stige Ø produced some 9,500 m³ of methane gas. A little less than half of this was collected and converted into energy. It is expected that exploitation of Stige Ø methane will be profitable for another 10 to 15 years.

Like other forms of alternative energy, the gas helps to reduce emissions of greenhouse gases.