The glycol issue discovered in connection with tunnel excavation work for the new Ring Rail Line under the eastern runway of Helsinki-Vantaa Airport is causing more expensive problems than was originally thought, Helsingin Sanomat reports.

Now the Finnish Transport Agency estimates that the glycol that has seeped into the soil underneath the airport will increase the construction costs of the Ring Rail Line by more than EUR 20 million.

Late last summer, in the tunnel under the eastern runway, a microbe population was discovered, the formation of which is believed to have been facilitated by the breakdown products of the propylene glycol that is used to de-ice airplanes. Initially the additional expenses brought on by this were estimated at a mere couple of million Euros.

The propylene glycol sprayed on the airplanes’ surfaces has been spread over an area that is 400-500 metres long. The de-icing agent has seeped along the cracks in the bedrock down to a depth of five to ten metres and has facilitated the growth of microbe populations there.

The microbe populations have to be removed from the tunnel, for they produce hydrogen sulphide, which is particularly harmful for the tunnel’s concrete structures.

According to the Finnish Transport Agency, in the area in question the tunnel has to be equipped with a double casing.

Provisions have to be made for possible maintenance work for around a hundred years.

The additional investigations into the issue and the re-planning of structures are causing considerable extra costs.

“There is a risk that the completion of the line will be delayed. To keep the schedule on track, despite this problem, we somehow have to speed up work elsewhere”, Finnish Transport Agency Director Kari Ruohonen said.

Before long, the Transport Agency and the user of the glycol, the Finnish aviation authority Finavia, will have to decide who should pick up the tab for the induced additional costs.

“The party that has caused the contamination of the soil is responsible for its actions”, Ruohonen says.

The two government authorities have not yet discussed the issue.

The Ring Rail Line, which should open to passenger services from the end of 2014, will be an 18km extension to existing commuter tracks and will connect the centre of Helsinki with Tikkurila via the airport complex.

It will cross the airport area itself in a twin tunnel of eight kilometres in length.

In the first phase there will be four new stations, two of them located underground.

The estimated cost of the venture is EUR 605 million, with the Transport Agency picking up nearly 400 million of this and the City of Vantaa EUR 186 million. Finavia is financing the underground station at the airport to the tune of EUR 30 million.

Source: Helsingin Sanomat

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