DCA provides stable base for world first in Norway

Construction of the world’s first large scale Carbon Capture and Storage (CCS) facility at Norway’s Mongstad oil refinery has got underway. The new test centre is being developed to capture and store carbon dioxide – a gas blamed for global warming – in a partnership between the Norwegian Government and StatoilHydro ASA, Norway’s largest oil and gas producer. Other partners for the European CO2 Technology Centre Mongstad (TCM) project are also expected to be announced shortly.

The 75,000 m2 site, located north of Bergen on Norway’s west coast, has been cleared of vegetation and some 150,000 m3 of top soil removed to expose firm bedrock. Main contractor Vassbakk & Stol has implemented site filling using rock fill material in 1.5 m layers. The average fill height is approximately 4 m whilst, at the highest point fill totalled 13 m.

The 1.5 m layers are being compacted with a minimum of eight passes by two Dynapac 18 t CA 602 single drum compaction rollers, both equipped with Dynapac’s Compaction Analyzer for documentation of the compaction work.

The use of documentation systems is a requirement from the project owner and has also proved critical in helping the operator track the number of passes being made. His task would otherwise have been impossible to manage over an area of 75,000 m2 according to Vassbakk & Stol Site Manager, Yngvar Eliassen.

V&S opted to equip the Dynapac rollers with RTK-GPS receivers providing centimetre accurate positioning of the Analyzer system.

“This investment proved very valuable as the project owner decided to accept the height measurements as final control of the levelling of each layer as well as using the roller data to calculate the compacted area.”

“This way, V&S avoided making time consuming and costly manual levelling of the compacted surface,” says Jon Åge Ödegaard, in charge of GPS-training and machine maintenance for Vassbakk & Stol.

As the height of each fill layer was pre-determined according to the compaction specification, dozer operators had a fixed target for their spreading operations. The fill should reach a specified height, no more, no less for each layer respectively.

As the dozers are equipped with the same type of RTK-GPS receivers they can easily find the correct layer thickness and maintain this over the entire area.

The contractor is very pleased with the documentation system and plans to extend the use of documentation systems on more sites throughout Norway. Even on projects where it is not required in the specifications. Compaction Analyzer makes the job easier for the operator by displaying the current location of the roller, as well as where previous passes were made.

The operator gets full overview of the compacted area and can avoid making too few passes which would result in not achieving the required compaction. At the same time, costly over compaction is avoided saving on machine wear, fuel and generally increasing machine efficiency.

Mongstad CCS
When the CCS facility is in place it will be used in conjunction with a combined heat and power (chp) station to be built in 2014. Norway, as the world’s fifth biggest oil exporter, recognises the potential in seeking to lead the way in developing technology to capture carbon dioxide. It will, according to the country’s Oil and Energy Minister, Terje Rils-Johansen, be the cornerstone of Norwegian environmental policy.