Prof. Carlos Delgado: The Eastern Option G10,50 is the best solution for Lot 3.2 of Struma Motorway

The construction of a long tunnel in the seismic region of the Kresna Gorge is very risky, dangerous and could lead to an ecological disaster

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Desislava Bakardzhieva

Prof. Delgado, would you please introduce yourself. What is your professional experience?

I am a professor in engineering geology. I have been teaching this specialty for more than 30 years at the Polytechnic University of Madrid, Spain. During this period I had the opportunity to cooperate with construction companies on major infrastructure projects not only in Spain but across Europe, as well as in a number of countries in South America and Africa. My professional career is inextricably bound also with my active participation in the International Association for Engineering Geology and the Environment (IAEG). Initially I presented Spain in IAEG as President of the Spanish National Group. Later, I became Vice-President of the International Association for Engineering Geology and the Environment, and in 2010 at a Congress in Auckland, New Zealand, I was elected President of IAEG. Currently I am President of the Spanish Engineering Geology Group at IAEG.

As an expert I have solved various problems related to the implementation of large-scale international projects, such as the Gibraltar Strait Tunnel, which had to connect Europe and Africa. My work was related to the assessment of the engineering-geological and seismic conditions between the two continents. The construction of this facility did not happen since the realization of the project was almost impossible because it was found that the plate of the African continent moves by 6 cm per year. It is practically impossible to shorten the tunnel by 6 cm every year. This required a serious reworking of the project. On my proposal now a suspension bridge is being designed.

I have also researched in areas known for their high seismicity where there are a number of problems related to the active faults, mainly in the countries of South America – Guatemala, Ecuador. The cases I have solved there were connected to a variety of sites – transport, hydro-technical facilities and others.

In Bulgaria you are invited by the Bulgarian National Group to IAEG to give your expert opinion on what is the best option Struma Motorway to pass through the Kresna Gorge.

Yes, I accepted the invitation with pleasure. The President of the Bulgarian National Engineering Geology Group to IAEG, Assoc. Prof. Kiril Angelov, acquainted me with the case and the possibilities for construction of Struma Motorway when passing through the Krupnik – Kresna area. I was given a great deal of information, a number of papers and studies on different options for completing the motorway linking Bulgaria and Greece.

I had the opportunity to read everything and then together with Assoc. Prof. Angelov we visited the Kresna Gorge to locate the engineering and geological conditions and the seismic peculiarities in this region.
I examined all the options of Lot 3.2 of Struma Motorway which have been offered over the years and I paid particular attention to the most discussed ones so far. I then drew up an expert report with my opinion in which I make conclusions in more detail about two options – the Long tunnel option and the Eastern option G10,50.

What are your conclusions about the long tunnel option?

The long tunnel – 15.4 km, between Krupnik and Kresna, has two tubes and is able to evacuate in the second tube through crossings. The length of the whole motorway route of this section, including road and tunnel part, is about 21 km. Each tube passes under the gorge between km. 378.3 and km. 399.78 – extremely risky solution. This option is not suitable for execution. Why? First, the designed tunnel is located in the Kresna seismic zone where was registered the strongest earthquake in Europe over the last 200 years. The seismic event happened on 4 April 1904 with two consecutive earthquakes with magnitude 7.2 and 7.8. This figure is extremely high for the entire Balkan Peninsula, as well as for Europe. The epicenter is related to the Krupnik fault zone. The existing nearby fault at Krupnik is also considered to be a generator of high magnitude earthquakes. There are several systems of active faults in the Kresna region, mostly in perpendicular or almost parallel direction to the main axis of the tunnel. The active faults are obviously the reason for the violation of the massif and for the formation of many cracks in it. In many cases these cracks are filled with viscose material called mylonite. It is produced by the friction of separate blocks, which are often saturated with water. Another reason is the effect of the possible change of the hydro-geological conditions of the water masses in the gorge after the construction of two large-diameter tubes (the two-way tunnels), which will drain the water from the mountain massif. It is very important to emphasize that cracks drain groundwater. Or, when passing a tunnel around it, a drainage system will be formed that will cause total drying of the whole massif. This will cause all trees and grasses to dry along the entire parallel of the facility.

For this reason I think that the construction of a tunnel through an active seismic zone is very risky, dangerous and could lead to an ecological disaster.

Have you encountered cases where the construction of long tunnels caused damages to people and nature?

Yes, I will share three cases from my professional experience. Two years ago I was invited to participate as an expert in a similar situation in my home country, but it was a matter of railway tunnels. In 2013 in the northern part of Spain under Sierra Astur Leonese were built two 24-km tunnels Pajares with a high-speed railway line. Although they are completely finished, they have not yet been put into operation. They are not used although they are perfectly implemented. The facilities are flooded by the drainage of the water over the tunnels and this does not allow the opening of the railway lines. The problem turned out to be too complicated and could not find a solution for four years. These two tunnels caused an ecological disaster, not to mention the financial losses. The investment in this large-scale project amounts to more than 1 billion euros.

Another unsuccessful site I have encountered in my career is the Chixoy tunnel in Guatemala. This large-scale project involved the construction of a 7 m-diameter hydro-technical facility. The tunnel had to connect a dam with a hydropower plant. The construction began in 1983. A tunnel boring machine (TBM) was used, which reaching the southern part of the tunnel crossed a fault zone, filled with mylonitized particles – fine, small and water-saturated. As soon as the TBM hit the fault, all of this water-saturated material, which was clay slurry, under pressure from the hydrostatic pressure (in the range of 130 – 140 MPa) buried the machine and created a high risk for the team operating it. The water from the mountain entered the tunnel and began flooding the excavated area blocking the equipment. The people working with TBM fled chased by the water masses. Fortunately they managed to save their lives. TBM remained in the tunnel as a plug to stop the mylonitized particles. The construction was discontinued. In this project the material losses exceeded 50 million dollars. A lot of time was also wasted.

The third case is the tunnel project under the Straits of Gibraltar, which I have already mentioned but I want to tell you in more detail. There is the border between Europe and Africa, the distance between which is only 15 km. For this reason it was logical to think that connecting the two continents through a tunnel is quite possible. The proposed facility was with two main tubes and an intermediate tunnel for technical maintenance. Experts began to study this opportunity 30 years ago. An International Commission was created in 1980 to promote the project and bring it to realization. Then it was not taken into account that the two earth plates of the European and African continents move towards each other. This movement is the result of two active faults in southern Spain and northern Africa. One is in the European zone of Alamas Palomares, and the other is in the northern part of Morocco. Both regions have a high seismicity with active anomalies and they have been associated with some earthquakes over the last 250 years. In spite of the serious and lengthy studies no option was found for a tunnel. I am convinced that the right decision was made. When I was working on this project, I suggested that the two continents connect with a suspended rope bridge with two supports at a distance of 5 km. This is technically feasible and recently this option was put under investigation. The rope bridge has many advantages over seismicity. In conclusion I will say that the project with the tunnel did not happen because of the active faults, as there are in the area of the Kresna Gorge in Bulgaria. It is unacceptable and very dangerous to build tunnels that cross through faults.

What did you find out about the Eastern option G10,50?

This solution will be implemented much faster; it is certainly more cost-effective and does not endanger human life and the environment. G10,50 divides the movement into two separate and spaced apart roadways, includes the construction of short tunnels and bridges. In the direction of Greece the route passes along the existing road I-1 (Е-79), and to Sofia it is along a new terrain to the east of the Kresna Gorge. The lane in the direction Sofia – Kulata will be on the entirely existing first-class road I-1 (Е79) to the beginning of the town of Kresna. This type of solution is often used in Italy and Spain, where parallel routes are being constructed on already functioning roads and thus they turn into motorways as a quick and economical alternative. And, believe me, they work very well.

The existing road in Kresna should be extended and improved in some areas but the advantages of its use are obvious. The two separate roads guarantee that the traffic will not be stopped in emergency cases. In addition, the materials to be excavated from the short tunnels can be used for embankments. The impact on the environment will be minimal, the costs will be lower. It is also very important that in case of tectonic events repair will be faster, easier and safer. The overall maintenance of the route will be more beneficial.

Some ecological organizations in Bulgaria insist that the motorway be realized outside the Kresna Gorge, to the east.

I got acquainted with this decision in detail but my expert opinion is that this option is wrong. There is no need for the motorway to be fully exited and built in the eastern direction around the villages of Brezhani, Stara Kresna and Oshtava and not to use the existing road Е-79. I think that such a decision will increase the impact on the environment. The implementation of two new traffic lanes will double the construction costs and at the same time Bulgaria will not get any advantages over the Eastern option G10,50.

Bulgaria has lost a lot of time developing the option for a long 15.4 km tunnel. This to some extent happened due to the insistence of some ecological organizations to realize this option. They now insist on the Eastern G20 option.

I highly respect ecologists but most of them are biologists and forest engineers. They are not experts in the study of faults; they do not understand engineering geology. Ecologists are not aware of the real danger; they cannot appreciate it. The active tectonic zones can be fatal for humans and constructions. Ecologists do not have the necessary knowledge and often defend wrong solutions, such as the long tunnel that could lead to an ecological disaster, perish plant species and take human lives in an earthquake, because such a facility will literally break. Not to mention the presence of radon in some sections of the Kresna Gorge that will be taken out by tunneling. Where will you store these radioactive rock masses? The fact is that there is always increased radioactivity in such active faults. Imagine what happens in an accident in such a long tunnel – people will be forced to stand for hours in a radiation zone and will be irradiated. A project should take into account all the negatives.

I do not understand why ecologists do not listen to the experts and do not defend the best solution for your society and country. We, as engineer geologists take care to defend both humans and the environment.

Is the behavior of environmentalists in Spain similar? Do they stop the development of projects? How do you work with them?

In my country experts meet ecologists and lead a constructive dialogue with different project specialists. Usually we quickly reach mutual agreement and projects do not stop. We have respect and I cannot say that we are fighting. They understand our arguments and we understand their wish to preserve nature. We have absolutely no problems with ecologists in Spain and we have good relations with them.

You visited the Kresna Gorge. What did you study there?

We started from Krupnik’s fault and we managed to examine it very well. Then we drove down the Е-79 route, where we made several stops and took shots of cracked rocks. Our first goal was immediately after the second tunnel to the south of Krupnik. Our study continued down the Е-79 route, and our next stop was the area around the Yavorov tectonic zone, to which we paid serious attention because of the many tectonic cracks in this area. We went through Kresna, made a left turn and started on the future new route of the Eastern G10,50 option, to find out what are the conditions for construction of the proposed tunnel Sveta Nedelya and bridges with high altitude.

What is your conclusion as an expert? Which is the best option for Lot 3.2 of Struma Motorway?

The Eastern option G10,50 is the best solution for Lot 3.2 of Struma Motorway. The construction of a long tunnel in the seismic area of the Kresna Gorge will be a big mistake. My conclusion is “No to the long tunnel” because of the high seismicity, the presence of faults and the real threat of an ecological disaster. “No to the option of the route on a new terrain outside the Kresna Gorge”– too expensive and unjustified from an environmental point of view. “Yes to the Eastern option G10,50” – I recommend this option as the best because of the minimal impact on the environment, the reasonable costs of construction and maintenance of the motorway and the normal term necessary for the construction.

Does this mean that if we choose G10,50, we can manage without problems to build Lot 3.2 of Struma Motorway?

This option will guarantee fewest problems and challenges for the contractors of the route, mainly because builders will work outside the areas with active faults in the region of the Kresna Gorge. This is the best option for construction.

Lot 3.2 of Struma Motorway will be built with EU funds, which implies choosing the best solution, to absorb these subsidies as efficiently as possible.

That is exactly why you have to realize the Eastern option G10,50, which is a quick and economical alternative to everything planned so far. Thus you will make the most of the EU funds for the development of your country. Spain has good experience in this regard.

The money from the EU that we have put in the construction of roads and motorways has very quickly produced positive effects. The areas through which we built routes have developed for a very short period; our economy has increased its performance and is now at a much higher level. In the 1980s Spain received EU funds to build its infrastructure. Now my country is putting money into the Union so that countries like Bulgaria can also build their missing routes. So, take advantage of the money effectively, do not waste it on unreasonable projects.

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Автор на 07.09.2017. Категория Accents, Новини. Можеш да следиш всички коментари и промени по тази публикации през RSS 2.0. Можете свободно да коментирате тази публикация

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