Lollikhuse - Infiltration of rainwater in soakaways

Samvirkende Boligselskaber, Lollikhuse division, has worked in cooperation with KAB to prepare a future analysis and subsequent action plans for the buildings. As part of this action plan, the department's sewage system was renovated and renewed in 2011. Lollikhuse is a division dating back to 1943 with 165 homes, divided into 3-storey angled blocks along Smørumvej in Brønshøj.

Project manager Thomas Kirkegaard of KAB was aware of the existence of WSUD and was aware early on in the project that it would be obvious to separate the sewer so that waste water and rainwater would be separated. When digging up the old sewer, it was possible to lay new pipes for the rainwater sewer, while elsewhere it was only necessary to excavate to a minimum depth in order to lay a new rainwater sewer.

The division is located in Copenhagen Municipality, the sewer is a shared system and the public sewer is managed by Københavns Energi. A survey of ground conditions in the area shows that the conditions were "perhaps appropriate" for infiltration of the rainwater through soakaways. A query to KE indicated that it would be possible to receive a refund of 40% of the sewer connection charge if all rainwater were disconnected from the sewer and infiltrated into the green areas.

The division's advisory group was very interested and decided to allow advisor Danacon to undertake the necessary geotechnical trials and prepare a financial estimate for establishment of the soakaways system. 

The project could be implemented, and following application and formal municipal approval of the project and permission for infiltration, the infiltration systems are now complete and have otherwise proved their worth in connection with the cloudburst over Copenhagen on 2 July 2011.

With the refund from KE, the division has paid most of the charges for renewal of the sewer and can instead use the earmarked funds for other necessary purposes within the division, e.g. renovation of the green areas, etc. The entire project is expected to be completed by the end of August.