The capacity at Bekkelaget treatment facility shall be expanded to double capacity. After the expansion has been carried out, there will be the capacity to receive waste water from 490 000 person equivalents (pe) and, including rain water/melted snow, the facility shall be able to treat approx. 85 000 000 m³ sewage water per annum.
Incoming waste water with a flow of up to 3,5 m³/s will be able to be treated biologically in a total of eight bio-basins, of which four basins are new. An increasing flow of the sewage amounts over 3,5 m³/s up to 7,0 m³/s will be treated with direct precipitation over new primary settling basins and lead directly to a new emission pipeline. The new emission pipeline was installed in the Midgardsormen project. At times of heavy precipitation amounts above 7,0 m³/s, the waste water will be lead to this emission pipeline via a seiving station, which was established in the mentioned project.
The sludge treatment will be completed with 2 new rotten tanks, a new sludge building and a new fat station. Some alterations will be made in the existing sludge building and parts of the dewatering and heat recovery equipment shall be replaced. The biogas that is produced will be led into the existing gas processing for upgrading to fuel quality. A new torch will be applicable.
The contract comprises all heating, ventilation and sanitation technical installations in the expanded sewage treatment plant at Bekkelaget, and includes the following:
The heating, ventilation and sanitation technical installations consist of ventilation, cooling, sprinklers for the new and parts of the old plant, flushing and fire alarms, sanitary installations, heating installations, humidity treatment filters and pressurised air installations for the new part of BRA, as well as external work in the administration building.
A new air treatment plant shall be established for the new part of the plant, with a new air intake in the southern escape tunnel with pre-heating via heat from the treated sewage water. Furthermore, a channel system and auxiliary fans shall be established around the plant for distributing air. The air in the fat reception and rooms in the cross hall is to be treated in separate aggregates. The channel system shall include all the necessary supply air/extraction points, regulating damper, fire damper, sound traps and insulation.
Acid proof channels for polluted extraction are to be laid to a new bio-filter, which is to be established in a separate niche in the access tunnel. Some channels will need to be altered so that the air is distributed between the old and new bio-filter in the best possible way.
The heating installations are to be based on an expansion of the existing water-borne installations, in which heat is provided from a heap pump and oil/gas boiler. After the expansion, the heat production shall be at two temperature levels, high temperature (HT) 70°C and low temperature (LT) 45°C respectively. Each system is to be equipped with accumulator tanks built on site of 75 m3 and 275 m3 respectively, and communication pipes between the tanks. A new electrical boiler of 1,5 MW shall be installed. Heat recovery from blowing machines and pressurised air compressors shall be established and connected to the plant. Furthermore, heat pipes shall be laid to the heat exchangers for heating the mixed sludge, fat and for heating the ventilation. In addition a new heat recovery system shall be assembled for extracting heat from the treated sewage water. The pipe installations shall be complete with the accompanying pumps, valves, insulation, expansion vessels etc.
The existing sanitary installations shall be expanded with combined flushing stations/fire stations for the new installations, as well as connection points for new machines. Ordinary sanitary installations shall be installed in the plant, such as toilets, showers, hand basins and slop sinks, as well as emergency and eye showers. The existing hydrophor installations with UV-treatment for treated sewage water shall be expanded. Points for high pressure flushing shall be established in hall 0 and the fat reception.
The existing pressurised air installations that provide instrument air shall be expanded.
Sprinkler installations are to be established with water fog in the access tunnel to the fat reception. The sprinkler installations shall be supplied from a separate water intake from a manhole on the outside through the tunnel system. Separate fire stations with options to connect to the fire service shall be established.
A new air treatment plant, with separate aggregates for a workshop and laboratory shall be established for the administration building's expansion. In addition the laboratory is to be equipped with special extraction. The existing heating and sanitary installations are to be expanded to cover the new parts. The new areas are to be heated with radiators and underfloor heating.