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Site surveys for nuclear project near completion

Fugro Moorside 3x2

Fugro is approaching the final stages of extensive geotechnical and geophysical investigations for a proposed nuclear power station at Moorside in West Cumbria.

The Moorside project, which is located close to Sellafield, has been proposed by nuclear company NuGeneration (NuGen). When complete, the power station is expected to have a gross capacity of 3.8GW.

To facilitate the project, the site investigations aim to provide geological and geotechnical information to inform the detailed design of foundations and ancillary structures, and to determine tunnel alignments.

Fugro is carrying out onshore and offshore site characterisation involving geotechnical, hydrological, topographical, geophysical and geo-environmental data acquisition. As part of the contract, Fugro is implementing its largest programme to date of sample testing and analysis in the UK.

In addition to informing the design and layout of the Moorside site, the data will support licensing, planning applications and other consents for the construction of the nuclear power station.

Moorside site investigations in detail:

Marine surveys

Work started in early December 2015 on the nearshore phase of the Moorside site characterisation. The initial phase of works comprised bathymetry surveys utilising Fugro’s geophysical vessels Fugro Seeker and the RV Valkyrie.

In early 2016 the Fugro Seeker returned to site to complete the survey and also undertake preparatory unexploded ordnance (UXO) clearance surveys for geotechnical borehole locations and seismic refraction lines. In April 2016 the Fugro jack-up barge Aran 250 joined the project to undertake 11 geotechnical boreholes, involving cable percussion boring, rotary drilling and an extensive in-situ testing programme.

The vessel Bravo Topaz was mobilised in April and completed a deep seismic reflection survey. Further work included bathymetric surveys from the Fugro vessel RV Discovery, and shallow seismic reflection and refraction surveys from the Fugro Seeker.

Onshore drilling

In addition to offshore activities, Fugro has undertaken a significant onshore drilling programme for Moorside which has utilised up to 18 rigs to drill 300 boreholes.

Cable percussive and rotary coring techniques have been predominantly used, as well as wireline drilling, for comprehensive investigations and analysis of ground engineering and hydrogeological data. These include in-situ testing of hydrofracture properties, high pressure in-situ dilatometer testing, packer testing, and pump testing to determine hydraulic permeability.

Fugro carried out rotary coring to depths up to 220m for the extraction of class I rock samples and large diameter rotary drilling for boreholes to truth the seismic geophysics and faulting analysis.

To reduce spoil, sonic drilling techniques have been employed to drill large diameter boreholes for the installation of pumping wells and to facilitate deep geophysical wireline logging. Additionally, some boreholes from the geotechnical programme have been reused to support 2D seismic reflection surveys.

Fugro will present data from the land-based and marine seismic surveys to provide a continuous, land-to-sea profile through the shallow transition zone (intertidal area) to help the design and construction of new infrastructure at the Moorside site.

The site team has also undertaken trial pitting and in-situ testing to determine viable locations for the storage of excavated spoil, which will be reused for landscaping. The land-based site characterisation will be supplemented by drilling and groundwater monitoring to support radiological screening undertaken by Amec Foster Wheeler.

Fugro is due to complete the majority of the site characterisation before the end of the year.

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