118
B. Schuchardt . H. Grann
11.3
The Europipe Project
In order to satisfy the increasing demand for natural gas in Western Europe a 640 km
long pipeline was installed from the Norwegian North Sea to Emden on the north German coast. The landfall of the offshore pipeline took place in 1994 in the German Wadden
Sea area. After lengthy consultations with the German state of Lower Saxony which
started in 1985, the Norwegian State Oil Company Statoil announced in 1990 that
Europipe landfall was planned to take place along the coast of Lower Saxony. During
this planning phase it became clear that the pipeline would have to cross the Wadden
Sea National Park of Lower Saxony. After evaluating a number of possible landfall routes
in terms of a wide variety of technical, safety and environmental criteria, a landfall
concept was proposed for the barrier island of Norderney in early 1991. It involved
traditional pipelaying methods in a formal Regional Planning Procedure which includes an Environmental Impact Assessment (EIA). A heated public disussion started,
fueled by a shift in the political scene in Lower Saxony, whereby attention became increasingly focused on environmental issues. Consequently, several alternative routes
were evaluated and discussed in detail (Grann and Schuchardt, in press).
At the end of a very complex planning phase, it was finally decided that the route
should cross the National Park of Lower Saxony through the Accumer Ee tidal inlet
between the barrier islands Langeoog and Baltrum. In November 1992 Statoil was
granted formal planning permission for the scheme, which included the construction
of a tunnel below the intertidal flats and dike. After additional efforts had been made to
optimise planning with regard to environmental considerations, final permission for
construction was issued in October 1993. Work commenced on land in November 1993.
In the Wadden Sea proper construction activities took place mainly in 1994 and early
1995, and delivery of gas commenced late in the same year (October 1995).
The pipeline landfall section is about 12 km long, extending from the 3-mile zone
seaward of the East Frisian Islands Baltrum and Langeoog, crossing a very dynamic,
shallow sandbank area (reef bars), following the Accumer Ee tidal inlet between the
islands, continuing into the shallow Accumersieler Balje before reaching the tidal
flats. For the purpose of burying the pipeline permanently in the seabed, a trench
of varying depth and with a trench bottom width of 12 m was dredged seaward of
the tidal flats. In addition, a 100-m-wide vessel access channel had to be cut through
the above mentioned sandbank area (see Fig. 11.1). In total some 3.4 x 10 6 m 3 of mainly
sand was removed to be used for beach nourishment or to be brought to an interim storage area offshore for later backfilling of the trench. Pipelaying into the open
trench was performed by a large pipelaying vessel in the tidal inlet and seaward and
using a smaller one in the Accumersieler Balje. The large pipelaying vessel could not
be used with its normal anchor pattern when operating in the shallow and narrow tidal
channel. Instead, 34 anchor piles were pre-installed and used as anchors during
pipelaying.
The tidal flats, the foreland and the dike have been crossed using a sub-surface tunnel (length about 2600 m). The tunnel start shaft was located behind the main dike.
The physical connection of the offshore pipeline in the trench and the land pipeline in
the tunnel was performed in a sub-sea floor tie-in chamber located in the Accumersieler
Balje (see Fig. 11.1). For details see Grann (this Vol.).
B. Schuchardt . H. Grann
11.3
The Europipe Project
In order to satisfy the increasing demand for natural gas in Western Europe a 640 km
long pipeline was installed from the Norwegian North Sea to Emden on the north German coast. The landfall of the offshore pipeline took place in 1994 in the German Wadden
Sea area. After lengthy consultations with the German state of Lower Saxony which
started in 1985, the Norwegian State Oil Company Statoil announced in 1990 that
Europipe landfall was planned to take place along the coast of Lower Saxony. During
this planning phase it became clear that the pipeline would have to cross the Wadden
Sea National Park of Lower Saxony. After evaluating a number of possible landfall routes
in terms of a wide variety of technical, safety and environmental criteria, a landfall
concept was proposed for the barrier island of Norderney in early 1991. It involved
traditional pipelaying methods in a formal Regional Planning Procedure which includes an Environmental Impact Assessment (EIA). A heated public disussion started,
fueled by a shift in the political scene in Lower Saxony, whereby attention became increasingly focused on environmental issues. Consequently, several alternative routes
were evaluated and discussed in detail (Grann and Schuchardt, in press).
At the end of a very complex planning phase, it was finally decided that the route
should cross the National Park of Lower Saxony through the Accumer Ee tidal inlet
between the barrier islands Langeoog and Baltrum. In November 1992 Statoil was
granted formal planning permission for the scheme, which included the construction
of a tunnel below the intertidal flats and dike. After additional efforts had been made to
optimise planning with regard to environmental considerations, final permission for
construction was issued in October 1993. Work commenced on land in November 1993.
In the Wadden Sea proper construction activities took place mainly in 1994 and early
1995, and delivery of gas commenced late in the same year (October 1995).
The pipeline landfall section is about 12 km long, extending from the 3-mile zone
seaward of the East Frisian Islands Baltrum and Langeoog, crossing a very dynamic,
shallow sandbank area (reef bars), following the Accumer Ee tidal inlet between the
islands, continuing into the shallow Accumersieler Balje before reaching the tidal
flats. For the purpose of burying the pipeline permanently in the seabed, a trench
of varying depth and with a trench bottom width of 12 m was dredged seaward of
the tidal flats. In addition, a 100-m-wide vessel access channel had to be cut through
the above mentioned sandbank area (see Fig. 11.1). In total some 3.4 x 10 6 m 3 of mainly
sand was removed to be used for beach nourishment or to be brought to an interim storage area offshore for later backfilling of the trench. Pipelaying into the open
trench was performed by a large pipelaying vessel in the tidal inlet and seaward and
using a smaller one in the Accumersieler Balje. The large pipelaying vessel could not
be used with its normal anchor pattern when operating in the shallow and narrow tidal
channel. Instead, 34 anchor piles were pre-installed and used as anchors during
pipelaying.
The tidal flats, the foreland and the dike have been crossed using a sub-surface tunnel (length about 2600 m). The tunnel start shaft was located behind the main dike.
The physical connection of the offshore pipeline in the trench and the land pipeline in
the tunnel was performed in a sub-sea floor tie-in chamber located in the Accumersieler
Balje (see Fig. 11.1). For details see Grann (this Vol.).