Ørestad. Treatment of road run-off

Double porosity filtration tested in Ørestad. Road runoff from 1.3 red. ha. treated in pilot system.

In Ørestad, Copenhagen's new urban district on the island of Amager, rainwater from roofs is fed directly to channels in the urban district. Rainwater from roads and parking spaces (road runoff), on the other hand, is collected in a separate system which is presently pumped out in Øresund after passing through a sand trap and oilseparator. The aim is also to feed the road runoff to the channel system, but as the channels are also used for recreational purposes the road runoff first has to be treated in order to ensure that it is of suitable quality. Double porosity filtration (DPF) may perhaps be suitable for the task.

A pilot system has been constructed beneath the grass in Byparken (the City Park) in order to test double porosity filtration technology. This technology is described under the method "Double porosity filtration." With an underground location, the treatment plant does not "steal" space in the park, thereby making the park multifunctional. Road runoff from CF Møllers vej, Arne Jacobsens Allé and the car park at Fields arrives at the filter via a pipe network on the large pipe which is currently used for pumping the road runoff away from the area, which totals approx. 32.5 red. ha. The plant is designed to process 1/25 of all the water, equivalent to 1.3 red. ha. With a pilot plant treatment capacity of 18 m3/hour, 95% of the annual runoff from the 1.3 red. ha. can be treated. By & Havn, Copenhagen Energi, Realdania, Copenhagen Municipality, Rambøll and Copenhagen University are responsible for the testing.Vand fra pumpestation (CBI)
Two versions of a Double Porosity Filter are being tested in the pilot plant: DPF-6-Layer and DPF-18-Layer. Both filters are 50 m long and 3.4 m wide, and have a design hydraulic capacity of 9 m3/h. DPF-6-Layer is cheaper to construct that DPF-18-Layer, which in turn has greater capacity and is expected to treat the water more effectively. DPF-6-Layer is made up of 6 double layers, each of which consists of a 10 mm thick limestone mat (low porosity trap layer) and a 6 mm thick high porosity flow layer, a total of 9.6 cm. DPF-18-Layer consists of 18 horizontal double layers, each double layer consisting of a 10 mm thick limestone mat and a 4 mm thick flow layer, a total of 25.2 cm.

Samples of road runoff were taken at the inlet and at each outlet during the first six months of 2007. A total of 25 rain events were analysed during the period. The inlet water contained on average 123 mg of suspended solids (SM) per L. Suspended solids is made up of the small soil and wear particles from the road environment which are suspended in the road runoff. After passing the DPF-6-Layer, the content was reduced to 10.5 mg/L on average, while after passing the DPF-18-Layer the road runoff was reduced to 1.4 mg SM/L on average. Both DPF versions are thus capable of meeting the Copenhagen Municipality requirement of 25 mg SM/L. When the suspended solids was removed, the road runoff's content of heavy metals was also greatly reduced. The main results are shown in the method description. Follow the link to the Basic Report for a full description

Sonia Sørensen, KE: "KE is eagerly following the testing. We need techniques like this if we are to be able to meet the political targets for water quality in Copenhagen. On the basis of the initial results, we have allocated funds in the Waste Water Plan for 2008 for a full-scale plant. This may be implemented if Double Porosity Filtration is able to meet treatment requirements and appears to be reasonable on a financial level."

Byparken in Ørestad, Center Boulevard, DK-2300 Copenhagen S
GPS (Krak): Lat: N 55º 38.074' Long: E 012º 34.563'
Google Maps link: http://maps.google.dk/?ie=UTF8&ll=55.634242,12.574477&spn=0.001157,0.003307&t=h&z=19

The description will be prepared in June 2009.

Name: Senior researcher Marina Bergen Jensen
Organisation: Skov og Landskab, KU-Life, Rolighedsvej 23, DK-1958 Frederiksberg C
E-mail: mbj@life.ku.dk
Telephone: +45 35 33 17 97

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