Overhead line in a protected floodplain woodland. “Extended Ecology” as basis for OHL planning and maintenance. CIGRE Document.

1. 21, rue d’Artois, F-75008 PARIS B2_107_2010 CIGRE 2010
http : //www.cigre.org
Overhead line in a protected floodplain woodland
“Extended Ecology” as basis for OHL planning and maintenance
A. HAGEN S. ABERLE
Sozialforschung und Umweltberatung H. MINICHBERGER
F. LENGLACHNER H. LUGSCHITZ
Vegetationskunde und Naturschutzplanung Verbund – Austrian Power Grid
Austria
SUMMARY
The construction of overhead lines, their maintenance, refurbishment and renewal is
nowadays seen with different eyes than before. Today environmental aspects are among the
most challenging aspects of high concern – in every part of life. The society’s point of view
has changed during the last 20 years – nature and environment are now of mayor interest. In
addition to techniques and science, the perception of landscape, fauna and flora is taken into
consideration during the planning process of an OHL. We call this “Extended Ecology”.
The project presented here for the replacement of a 220kV overhead line which will run
along an existing OHL-corridor through a floodplain woodland in a nature protective zone is a
good example of the new approach. To create harmony between ecology and economy is a
precondition of the project. The responsible and careful treatment of the existing OHL-
corridor during the last few years has resulted in an improvement of conditions. In only a few
years the number of endangered species living in these areas and listed on the “Red Data
Lists” has increased from 23 to 40.
The city of Linz is the capital of the Region “Upper Austria” and is Austria’s centre for heavy
metal industry with European dimensions (e.g.VÖEST Alpine). The city is also well known
for advanced technologies and recently for modern arts (ars electronica, Klangwolke,
European Cultural Capital 2009). The expansion of the industry and of dwelling areas reduced
and endangered the natural environment; therefore - and as a logical compromise - several
areas were nominated as natural protective zones. Existing overhead lines run through some
of these, and some of them need to be uprated.
Herbert.Lugschitz@Verbund.at

2. Two parallel 110kV OHL run through the protected floodplain woodland of “Donau-Traun
Auen”. One of them was built in the 1940ies and needs to be rebuilt as a 220kV line. Since
2006 ecological treatment techniques have been in practice in these corridors. This area
originally showed a pattern of degraded nutrient-poor alluvial meadows, rich in invasive
neophytes, fragments of semi-dry calcareous-grassland, tiny large sedge or reed beds in moist
depressions and large short rotation coppice woodland.
During the last years additional ecological compensation measures have been implemented:
ponds have been created and open gravel areas generated by construction measures have been
re-vegetated taking into account the soil seed bank and using proved techniques of nature
conservation. Significant success can be reported after only a few years of subtle treatment
techniques aimed at optimal development of target vegetation. The typical composition of
plant species could be restored in core areas of nutrient-poor alluvial meadows. The number
of species enumerated in “Red Data Lists” has increased from 23 to 40, including highly
endangered plants demanding moderate disturbance regimes.
If ecological treatment is continued, further increase of environmental conservation value in
the corridor can be expected.
KEYWORDS
extended ecology, endangered species, ecologic corridor maintenance, technical facilities and
nature, sustained right of way management
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3. Principle aspects
At a first glance it may appear peculiar to present an overhead line crossing a protected area
as an ecological project of high value. For a very long time the public considered overhead
lines as “not ecological” – a position which can be seen as opposition to a technical and
forced intervention in nature, which lasted over decades. Nature which was endangered by
humans was seen as valuable and should be protected. This led to a revaluation of nature and
the environment.
In addition to techniques and science, the perception of landscape, fauna and flora is taken
into consideration during the planning process, the erection as well as the maintenance of an
OHL [1].
Figure 1: Two parallel 110kV overhead lines in the protected floodplain woodland of
“Donau-Traun-Auen”. The right one is to be rebuilt for 220kV.
Nowadays grid operators pay more and more special attention to nature and the environment
during the planning and maintenance of overhead lines. They follow a position of “extended
ecology”. This means, that also the subjective perception and the emotion of people – as part
of the environment – are taken into consideration. This “extended ecology” is the base for a
new culture of planning, which connects nature, environment and the knowledge of experts,
as well as individual personal perception.
Under these aspects the sensible project – the crossing of a protected area – has become an
example of how overhead lines can be the ecological best solution for the transmission of
energy. If they are integrated properly, they are the most sustainable solution and most
agreeable for the area.
The project is furthermore an example of how important a permanent and esteem
collaboration is between industry, energy suppliers, biologists, sociologists and above all the
persons responsible for environmental protection especially the authorities.
Project area
The nature protected floodplain woodland “Traun-Donau-Auen” lies on the periphery of the
city of Linz and is an important regional recreational area. Two 110kV double circuit OHL
presently run through these woodlands, one of them to be replaced by a 220kV-line.
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4. At a similar OHL-replacement at the neighbouring region (Pichling) it was proven some years
ago that OHL can be erected in a responsible way even in a sensitive environment.
Experiences gained there are the base for the current project.
The present example is also a symbol for the development of a city, a development which
took place in a rapid and consistent way over the last 2 decades. In former times Linz was a
synonym for a smoky and culturally uninteresting industrial city and center of the Austrian
heavy industries (VOEST). Today Linz is a very “new” industrialized city with top
environmental performance – due to concentrated initiatives in the field of environmental
protection and cultural events. The amount of 47% green areas and 7% water areas
characterize this. The quality of the air is among the best of Austria´s regional capitals. There
are more jobs than inhabitants and the rate of unemployment of 2,5% is very low.
Linz has become a model for environmental protection in dense industrial regions. The
cultural events are also trend-setting. In 2009 Linz was European cultural capital, together
with Vilnius. The cultural tradition includes among others the composer Anton Bruckner who
lived there. The new Ars Electronica Center is a meeting point for modern technology and the
new Museum of Modern Art “Lentos” ranks high in international reputation.
Sustained right of way management
At this project the corridor maintenance also follows the “sustained right of way
management” and the principles of “extended ecology”. This brings advantages for nature.
The corridor can become a new living space for animals and flora which would not previously
have found this living space permanently e.g. in an economically used forest. The corridor
provides a diversified landscape and therefore variable living areas.
The sustained right of way management does not necessarily only mean the “normal”
maintenance of the right of way, improvement of habitats for fauna and flora, extension of
biotopes and their care. It may also cover the support of social-cultural projects in the
surrounding area of the route (examples: Natural Park “Kaunergrat”, research project
„Keltenstadt“ together with the Museum of Natural History Vienna [2]).
The sustained right of way management follows these principles:
- Safety of operation has the highest priority
- During the maintenance work the needs of the environment and landowners are taken
into best possible account (precautionary principle)
- During maintenance the natural and cultural background of the region are respected as
well as the actual ecological situation
- A permanent dialogue is kept up with landowners and representatives of various
interests.
- To keep the financial advantages in the project area, measures are carried out by local
people as much as possible (farmers and forestry experts)
Ecological aspects in the “Donau – Traun – Auen”
The present project is a good example to show the positive results of ecologic measures in an
OHL-corridor.
Nature reserve Traun-Donau-Auen is considered of national significance due to its diversity
in habitats - covering nearly all possible habitat-types typical for the region - and its
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5. abundance both of plant and animal species. So far 680 vascular plants, - about 30 % of
"Upper Austria´s" total number of indigenous or established taxa have been observed, among
them more than 27% of either nationwide or regionally threatened species, listed in the “Red
Data Inventories” [3].
If, as in our case, overhead line corridors cross riverside belts of floodplain woodland to a
large extent in formerly grazed semi-open landscapes, consisting of patchy shrubs and alluvial
grassland, effects of habitat dissection can be minimized. Broad hedgerows of semi-stable
natural shrub-communities following the transverse axis as connectivity-corridors and
curvilinear soft edges of the OHL-corridor boundaries reduce habitat dissection effects for
adjacent forests. At the same time OHL-corridor management offers the chance to conserve
this threatened and valuable type of semi-open cultural landscape, characteristic for
(peri)alpine rivers, including endangered dry to wet nutrient-poor grassland habitats. Possible
negative impacts on certain bird species, can normally be minimized by appropriate measures
with good results.
The former relatively even corridor maintenance was similar to intensive short rotation
forestry. It was only determined by the height of trees, and caused high disturbance effects.
Now a management routine with controlled low-level disturbance has been established.
Therefore management techniques are adapted to the current mosaic-pattern of vegetation,
aiming to develop semi-stable shrub-communities requiring minimal tree removal. If OHL
corridor management is optimized in this way, it meets the requirements of nature
conservation in a perfect way.
In the past, the investigated OHL corridor showed a pattern of degraded nutrient-poor alluvial
meadows let lie fallow, rich in invasive neophytes, fragments of semi-dry calcareous-
grassland, tiny large sedge or reed beds in moist depressions and extensive woodland
coppiced in short rotation. Since 2006 ecological management techniques are in practice.
After only three years of complex management aiming at optimal development of target
vegetation, significant success can be reported. In core areas of nutrient-poor alluvial
meadows, then showing severe losses of characteristic plant species, the typical species
composition could be restored, while it succeeded in repressing invasive neophytes. In
addition almost totally silted up ponds and ditches have been enlarged. Small open gravel
areas generated by construction measures (from work on former lines) have been re-vegetated
taking into account the soil seed bank and applying reliable techniques of nature conservation,
using only autochthonous seeds, which were collected in the wild. Since then, under an
accurate management regime, initial semi-dry grassland habitats which are rich in typical
plants and almost lack invasive neophytes could be established.
In comparison with the situation before, the number of vascular plant species enumerated in
“Red Data Lists” has increased from 23 to 40 taxa, including critically endangered plants
demanding moderate disturbance regimes.
If ecological corridor management is continued, further increase of nature conservation value
can be expected in the near future.
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6. Number of Red List species
before and after ecologiocal corridor management
45
40
3
35 5
1 - critically endangered
30
2 - endangered
Number of species
25
1 19
1 3 - vulnerable
20
11 regionally endangered
15
10
13
5 10
0
Survey 2002 Survey 2008
Figure 2: left - The population of Erect Clematis (Clematis recta), here visited by a rose
beetle, endangered in "Upper Austria", increased because of adapted management. Right: the
number of red list species increased from 23 to 40
Further examples for “extended ecology”
Protection of endangered species of falcons
In the year 2008 a project to protect endangered species of falcons was started in cooperation
with the Institute for Game Ecology of Veterinärmedizinische Universität Vienna.
The “saker-falcon” is on the red list of endangered species and is among the animals which
are dying out in Austria. Its live stock is below 20 couples. The saker-falcon prefers
transmission line towers for his nests which because of their height provide a perfect view for
hunting and breeding. Therefore more than 60 towers are equipped with artificial nesting
facilities at the level of the upper crossarms.
Figure 3: The saker-falcon found perching on transmission towers
Nowadays, in eastern Austrian Regions and Hungary the saker-falcons depend on such
nesting aids on transmission towers. Examples are also known from eastern Slowakian
regions, where the number of couples have increased from one to 10 couples within 15 years
due to nests on towers.
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7. LIFE-Nature Project Bustard
The number of bustards in Austria was reduced from 700-800 (in 1940) to 150-170 (in 1970)
and was further reduced to app. 60 (in 1995). During the last years the number has increased
slightly. The core areas are now also in areas which are crossed by OHL. Utilities have
already given special attention to the bustard in the past when building OHL in such areas.
This was mainly done by the proper selection of routeing (to avoid breeding areas and to mark
the line)
Together with ornithologists and the Technical University Graz new bird warning plates were
developed. They can be mounted at conductors. In a LIFE-Nature Project together with other
utilities app. 2800 such bird warning plates and app. 4500 warning balls were mounted on
three OHL for the protection of bustard (LIFE05 NAT/A/000077).
Figure 4: left endangered bustard, right warning plate for birds in a double bundle (mounted
on a spacer in a double bundle)
Line configuration, construction, maintenance
Two parallel double circuit 110kV OHL run through the protected swampy area of “Donau-
Traun Auen”. One of them was built in the 1940ies and needs to be rebuilt as a 220kV line.
The route is 1204 m long. 5 towers need to be rebuilt. 80% of the route runs through a
protected area. An important aspect to getting the permission was that good results could be
presented from the existing right-of-way-management, and reference could be made to similar
projects in the vicinity. In these projects the given conditions regarding nature protection had
been fulfilled.
The authorities for nature protection were involved at a very early stage. Their suggestions
and demands were taken into consideration from the beginning on.
The preconditions for routeing, design, erection and maintenance of the new 220kV-line,
which were given by the authority, were:
- not to exceed the existing corridor
- not to touch the high valued forests at the edge of the corridor
- to keep the height and towers configuration of the 220kV line as similar as possible to the
existing 110kV line in order minimize the risk of bird collision. This is made possible by
using appropriate conductors and optimising the internal clearances and tower spotting.
- To optimize the visibility of the conductors by the use of proven technical measures.
These measures follow experiences from other areas in the grid.
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8. - No towers in high valued biotopes, which would be difficult to regenerate
- To minimize disturbances to animals, no interference is allowed in sensitive areas during
erection and stringing. This is reached by restricting working periods (e.g. not during the
breeding time) and precaution in tight cooperation with biologists and experts from nature
protection bodies.
- Careful restoration of areas which were affected during the work using approved methods
from restoration-ecology
- to follow given access routes for the erection and for future maintenance work
The new towers follow as much as possible the shape of the existing ones. This supports the
effect of habituation on those structures which have already existed since decades [4]. They
are galvanized lattice steel structures and in-factory-Duplex coated. This increases the dura-
bility of the coating and will reduce the efforts for further corrosion protection measures [5].
Conductors are double bundles 32mm ACSR 560/50, porcelain long rod insulators will be
used. Bird warning balls will be mounted on the earth wires and warning plates on the
conductors (between the sub-conductors). For environmental protection reasons foundation
works are only permitted during the winter period, tower erection and stringing works are
allowed during autumn.
Résumé
“Extended ecology” is the basis for the planning and maintenance of OHL. It brings together
nature, the environment and the knowledge of experts as well as human perception.
The results achieved with sensitive right-of-way-treatment in protected floodplain woodlands
are very encouraging. In only a few years the number of endangered species living in these
areas and listed on the “Red Data Lists” has increased from 23 to 40. With such treatment the
right of way clearly has an important function not only for the line, but also to create (resp.
keep) a high diversity of species, for endangered species and for recreation.
BIBLIOGRAPHY
[1] “High voltage overhead lines, environmental concerns, procedures, impacts and
mitigations”, Cigre Publication 147, WG 22.14, 1999
[2] „Roseldorf - interdisziplinäre Forschungen zur größten keltischen Zentralsiedlung
Österreichs“ Forschung im Verbund, Band 102, Wien 2009
http://www.keltenforschung-roseldorf.at/sandberg.htm
[3] F. Lenglachner & F. Schanda. „Biotopkartierung Traun-Donau-Auen Linz 1987“
(Naturkundliches Jahrbuch der Stadt Linz 34/35 1990, pp 9-188), Linz 1990,
www.linz.at/presse/2005/200509_9937.asp
[4] E. Gehmacher, A. Hagen, „Integration von Freileitungen in die Natur –NANU“
(Integration of overhead lines into the environment), BOAS, Vienna, 1998
[5] A. Ernst, T. Gros, H. Lugschitz, “Corrosion protection of steel towers and camouflage
of lines using the Duplex-system”, Cigre session 2004, paper B2-313
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