GGLF (Green Gas Lolland Falster) – 3 HDD’s

Description

Three (3) HDD installation for the project GGLF (Green Gas Lolland Falster). The three crossings are world-class as they are long and deep, and working under strict environmental conditions. The Scope of Works will be considered to cover all phases of work from design maturation to installation, testing and pre-commissioning. Lot 1: The tender concerns the installation of steel pipe on three sections of the Green Gas Lolland-Falster gas pipeline project. The sections in this scope of work cross three marine crossings, and will be in-stalled using the ‘HDD’ technique, whereby the entire length of pipe will be pulled as a string through a sub-surface hole prepared using ‘Horizonal Directional Drilling’. The three HDD covers construction of the following: • HDD crossing of Færgestrøm: approximately 1884 m long 10” steel pipeline • HDD crossing of Grønsund: approximately 1925 m long 10” steel pipeline • HDD crossing of Guldborgsund: 1255 m long 10” steel pipeline The HDD trajectory is expected to be through soft chalk, which is dominant in this region. The thickness of the chalk on these crossings is 10’s of meters. The onset of the chalk is between 5-20m on the landfall sections of the project where the HDD begins and ends. Soil layering above the chalk is typical of this area, with post-glacial tills, overlaid or interbedded with post-glacial clays, silt and sands. Flint is present in the region, and from the soil investigations carried out on these crossings seen to represent approximately 1-2% of the total rock volume sampled in the geotechnical borehole program. Boulders are present in the till layers. The phase of work include detailed design, installation and testing of these sections of the pipeline from initial site preparation, through pre-commissioning. The work is complete when the pipe is suc-cessfully installed, filled with nitrogen gas, and sealed, ready for tie-in to the land-line and the rest of the pipeline. For further information regarding the tendered contract and the scope of work the Contracting Authority refers to the Tender Document package, including Particular Specifications (doc. no. 21/09717-27).