The Malta Independent 14 April 2021, Wednesday

Gozo tunnel: Problematic geology ‘may cost lives during’ construction phase – expert

Jeremy Micallef Monday, 19 November 2018, 10:05 Last update: about 3 years ago

There are problems both in terms of the number of faults and large displacements, and also in the stratigraphy of the rock composition between Malta and Gozo, geologist Dr Peter Gatt told The Malta Independent yesterday.

Gatt was contacted by The Malta Independent after his comments on social media platform Facebook on the much-discussed topic of the Gozo tunnel, where he warned about “problematic geology between Malta and Gozo”, to the point where he believes that the construction phase may cause loss of life.

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“… technical matters, if not assessed seriously by experts of Malta’s geology, will cost lives during the construction phase. Another reason why I steered clear from this project,” the geologist wrote on Facebook. 

The idea of a permanent link between Malta and Gozo has been spoken about by both major political parties for many years, and originally there was disagreement - where the PN wanted a tunnel and the PL wanted a bridge. It seems that now, both parties have settled on the idea of a tunnel.

Back in March 2017, Prime Minister Joseph Muscat said that the government was committed on delivering the promise with regards to the tunnel, as a permanent link between Malta and Gozo.

Muscat had said that this project will take time as a lot of studies need to be carried out before works actually start. In May, Muscat had also said that the tunnel could be operational within seven or eight years.

Faults in the rocks refer to the breaks in the rocks with a vertical displacement – vertical displacement being the shifting of land in a vertical direction, resulting in a long-term change in elevation.

“We’re talking of faults where the vertical displacement would be even more than 100 metres,” Gatt (above) said when contacted by The Malta Independent.

Gatt insisted that even if you compare this with the faults which were encountered during the excavation of the Channel Tunnel between France and the United Kingdom, the vertical displacement in the rocks in that area was less than 15 meters.

“That would create problems in itself, both in terms of damage that you find in the rock, and also changes in the type of rock you would encounter.”

He also commented on the gaps in the stratigraphy of the area – stratigraphy being the branch of geology concerned with the study of rock layers (strata) and layering (stratification).

“I have myself, a few years ago, discovered a gap in the stratigraphy of 50 metres within the lower coralline limestone in Zonqor.”

This, he says, is because our stratigraphy is still based on what the British had done about 40-60 years ago, which is a long time in scientific terms and he questions why nobody has bothered to update it.

He also raised the issue that we do not have a national geological survey in Malta, the only European country that does not have an entity of the sort.

“In the case of the United Kingdom when they were building the Channel Tunnel, same with France, the British Geological Survey was very active and involved in actual testing and monitoring of the excavation. They were also involved in the pre-excavation and assessment of the geology.”

Minister for Transport, Infrastructure and Capital Projects Ian Borg announced in August that the entrances to the tunnel would be Nadur, below the Kenuna Tower and Imbordin, a hamlet between Pwales, and Manikata that forms part of St Paul’s Bay.

“This is not like constructing a normal road, you don't have all the problems associated with constructing roads. The tender was made in such a way as if this was just going to be the normal construction of a road. “

“Obviously when it comes to tunnelling the construction is completely different. The approach has to be different, you need to go into more detail and you have to have certain tests which weren't even listed in the tender.”

Replying to a parliamentary question made by PN MP Chris Said earlier this month, Borg said that along with the technical planning for the Malta-Gozo tunnel, the preparation of the tender documents necessary to issue the public call for the project is currently underway.

The chosen tenderer will be responsible for the management of the project as well as the actual digging and building of the tunnel. All other services related to this project will also form part of the tender.

During the budget speech, last month, it was announced that geological studies for the zone had been finalised and will form the basis for the design of the tunnel.

Over the last weeks, the result of these studies have been discussed with several experts, entities and the concerned authorities and was now being finalised.

Environmental impact assessments required for development permits of such a large project are also being done. Topographic surveys of the zones where the portals of the tunnels are being proposed in Malta and Gozo are being carried out.

Other economic studies are underway which are necessary to ensure that this new infrastructure will be used in the most sustainable manner.

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