Oslo city is growing fast and will do so in the foreseeable future. In order to maintain the quality of the water in the Oslo fjord, it is necessary to expand the purification capacity. The tiled sewage treatment plant cleans 40 per cent of the Oslo municipal wastewater. But it is overloaded and cannot meet new environmental requirements. Therefore, five years ago, the Water and Wastewater Administration in the City of Oslo began the extensive job of development to significantly increase capacity. Omexom Norway, the distribution network Oslo, has performed high voltage work at the plant.