Bekkelaget sewage treatment plant (UBRA)

Oslo’s largest environmental project

Christoph Hannich

New pumps and pipes for the extended sludge treatment (Image: PORR AG)

In May 2017, PNC Norge was awarded a contract to expand the sewage treatment plant in the Norwegian capital, Oslo. As a result, PORR’s Norwegian subsidiary is responsible for detailed design, supplying, erecting and commissioning all machine technology and process technology equipment, as well as pipeline engineering at the sewage treatment plant. The starting gun for design work was fired as soon as contracts were signed. The order volume is NOK 346 million, about EUR 35 million. The project is to be completed as an internal joint venture together with PORR Deutschland GmbH . Infrastructure and Civil Engineering . Berlin branch.

Oslo is the fastest growing city in Europe. The city’s administration has been forced to expand the existing sewage treatment plant in order to maintain the water quality of the Oslofjord. The “UBRA” project will see the sewage treatment plant’s capacity expand from 270,000t about 500,000 population equivalents by the year 2020. UBRA stands for “Utvidelse av Bekkelaget Renseanlegg”, which translates to “expansion of the Bekkelaget sewage treatment plant”. The project is expanding the plant below ground to the north and south, and has necessitated removal of 465,000m³ of mountain.

Wastewater treatment involves cleaning wastewater both mechanically and biologically; tertiary treatment uses sand filtration and sludge treatment with thermophilic sludge stabilisation and corresponding gas processing. Upon completion, the plant is set to handle and treat wastewater, rainwater and melt water simultaneously at a rate of 7m³/s or 850 million m³/year. In addition to providing equipment for the new plant, PORR’s contract also involves replacing some equipment in existing areas of the plant. This presents particular challenges in terms of transport logistics and installation, as the entire sewage treatment plant is almost entirely situated in underground rock caverns.

Inspection of existent installations. (Image: PORR AG)

Plant installation

The scope of delivery and erection includes a fine screen system, 14 chain scrapers and scraper bridges to remove sand and sludge, 120 different pumps, a membrane aeration system complete with turbo blowers, new centrifuges for sludge dewatering, two new digesters with central mixers, a complete lime-milk preparation system, more than 20 heat exchangers, almost 100 stainless steel penstocks, about 1,100 pipe valves and 14km of stainless steel piping.

Design for sewage sludge treatment has been completed, as has the bulk of plant construction. Work is currently ongoing to install the new sewage gas system. In summer 2018, work to install equipment in the biological treatment area’s four new aeration and clarifier tanks will begin. In 2019, equipment will be installed in the mechanical pre-treatment area and tertiary treatment area with sand filtration. Completion of mechanical installation at the plant is planned for early 2020, and will be followed by the start-up phase and test operation. The plant should then enter regular operation in 2020.

The contract was awarded in a negotiated procedure with preliminary market dialogue and a pre-qualification process. A decisive factor in awarding the contract was the efficient manner in which PNC Norge combines its competencies in the Norwegian infrastructure market with the specialist expertise of PORR Deutschland in the field of wastewater engineering and plant construction.

Project data

Client Oslo Kommune, Vann- og avløpsetaten
Contractor PNC Norge AS
Project type Civil engineering . Infrastructure . Power plant construction
Project scope Design , equipment installation and commissioning of the expended sewage treatment plant
Construction start May 2017
Construction end Early 2020
Country Norway

Procedural steps in plant expansion

Pre-treatment Inlet screw pump station, three-line
Screen plant, four-line
Sand and grease trap, four-line
Pre-clarifying with precipitation and flocculation, eight-line
Biological treatment Aeration tanks, four-line
Secondary clarification, four-line
Tertiary treatment Sand filtration, sixteen-line
Sludge treatment Thermophilic anaerobic sludge stabilisation, two-line
Sludge dewatering with centrifuges, two-line
Gas system, two-line

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