Nature & Environment

From mountain water and riverscapes

Ecologists and engineers have a lot to do to protect nature in the building phase and to develop new meadows, forests and creeks - with frog ponds and grey heron colonies, maple trees and trembling poplars.

The motors are still roaring, people are welding and hammering and the lorries are driving around. Cranes heave stones into the air, turn and lower the weight again. But they are careful not to tunnel into the tree roots. The sodium vapour lamps, which have been installed on the construction site are glare-free and have a pale orange light. In the womb of the Deutschlandberg, the “Schilcher city”, where vineyards, meadows and forests stretch out over the countryside and the Laßnitz river flows, nests one of the largest grey heron colonies south of the Alps. The birds crouch, family beside family, in their high brushwood nests and stalk around the shallow water in search of food. Not far from them is the northern portal of the Koralm tunnel. Ornithologists had studied the colony long before the tunnel drilling machines began to howl - in the planning phase for the environmental impact test. A range of protective measures were worked out. The trees must not be cleared in the breeding season but instead between August and January. At the annual nest counting it was determined that the grey heron colony is intact.

How to move a piece of Lavant

The environmental experts, agricultural planners and hydraulic construction technicians, among others, have planned a renaturalisation measure with an enormous amount of effort in the other side of the Koralm tunnel in the Kärnten Lavant valley: they have transferred a part of the river by 1.4 kilometres. We need space for the high performance route of the railway line and the Lavant valley station but also for the stone and debris, which is carted day after day away from the growing tunnel. But this means that the retained volume that protects the community of St. Paul downriver with its 21 villages against possible flooding is lost. So, similarly to the Schwarza area for the Lower Austrian portal of the Semmering Base Tunnel, we must clear away terrain and set new retention areas in addition to the Lavant, for a section, digging out a new river bed. 20 hectares of compensation area was gained as well as a significantly healthy river environment. The Lavant itself was for a long time separated from its backwaters, wedged into a bone straight trench. Now it can wind and snake around again in any section, according to its natural dynamic in a wide bed with so-called expanded, sometimes steep and sometimes flat banks with bars and sand banks, hollows and shallows. It can be seen from the cycle path.

Yellow-bellied toad and crested newt

The ‘old’ Lavant remains as a weak flowing tributary. Between it and the new river, an island is formed with an alluvial forest, wetlands and all kinds of still waters, in which deadwood, root stocks and stones are being introduced. A natural calm zone with no access by people is being established - so that they can flap around here and peck for food: the fast sandpiper and the whistling oriole. In 2011 the restructuring was completed and the first monitoring results showed: the barbels and graylings bustle about in the river, yellow-bellied toads and crested newts glimmer in the ponds and in the meadows and the precious Lavant valley terrestrial orchids gleam in red and violet.

4,300 water measurement points in the Semmering area

Conservationists and scientists also have a constant eye on the mountain water of the Koralpe and the Semmering. Years before the tunnel construction was started, they began to record data - in the Semmering area, believe it not there are 4,300 measurement points; in the Koralm there are around 350. The smallest changes are recorded. Maps are created, hundreds of sources, springs and streams are created and samples are taken and brought to the lab. The most important principle: the quality and quantity of drinking water must remain protected. The Koralm sources - as discovered by this research - are not negatively affected by the tunnel construction: they feed from the near-surface mountain water, in the loose stone and the weathering zone. The tunnel runs much deeper. On the Semmering, geologists and hydrologists take drillings up to 850 metres deep to research the stone, the water and its streams. In actual fact the water-containing layers of chalk and dolomite must be avoided as well as possible or crossed using the shortest possible route with the route of the base tunnel. Where this isn’t possible, particular mountain sections are sealed and drainages are dug to divert the rivulets. In the Grasberg and the Large Otter, where the stone contains lots of water, the engineers have constructed water pipes.

60,000 trees and bushes

The renaturalisation on the southern line will not be completed for a long time. There is a lot that we won’t see in full for years yet, including the 7,000 plum trees, walnut trees and maple trees, willows, ashes and oaks that have been planted in the shifted Lavant. At Gussendorf on the Styrian Laßnitz river, of which a section has been moved, 11,000 trees and bushes have been planted. All in all, over 60,000 new plants are already flourishing and there will be even more. Everything is happy and healthy. At the Freight Centre Vienna South primary school children have got to work over the last year. Together with teachers and locals, they have planted some promising things besides small gray poplars and littleleaf linden: trees, which will later grow apples and pears, sweet cherries and soft wild cherry.