HR3 & KF Geo Investigations UXO Desk Study 2012 · PDF fileHR3 & KF Geo Investigations UXO Desk Study 2012. UXO ... where the unit is high lying 27 ... 27 February 2013 OWF HORNS...

127-02-2013 OWF Horns Rev 3 and Kriegers Flak - Geo Investigations

HR3 & KF Geo Investigations

UXO Desk Study 2012

UXO - UneXploded Ordnance

Unexploded Ordnance (UXO) is defined as military munitions that have been:

• Primed, fused, armed or otherwise prepared for action

• Fired, dropped, launched, projected, or placed in such a manner to constitute a

hazard to operations, installations, personnel, or material

• Remain unexploded either by malfunction, design, or any other case

Generally and historically not an integrated or well-known part of Danish offshore pre-

investigations until recently (especially Anholt OWF).

Ad hoc surveys and actions taken care by FKP EOD, SOK (Danish Marine)

Energinet.dk hired Danish Consultants NIRAS led by former weapon/UXO officer Erik K.

Lauritzen to conduct UXO Desk Studys for the two OWFs


UXO Desk Study 2012 – Results HR3:


UXO danger zone in the middle of HR3 pre-investigation area.

Military training zone Oksbøl (5 km radii to 20km). The maximum safety zone

extends to 25 km (light pink). A previous 33 km zone is indicated by the green line.

UXO Desk Study 2012 – Results - HR3


From: ”Munition im Meer”:

Red: British mines from WWI

Green: German LMB mines from WWII

Blue: British air deployed Mk I-IV from WWII

Aluminium! Danger zone!

SW of HR3, not relevant

Iron, rusted away, diffuse



According to the reports, the last time a LMB mine was found i Danish waters was in Ålbæk

Bugt in 1992. The batteries were dead.

A complex trigger system, very unlikely to explode, however very complex!



According to the reports, a few of the LMB mines exploded during last part of WWII

The 70 mines were dropped by ships along two paths, with given coordinates for the end

points. No mines have ever been detected by NATO (SSS), nor reported found!

UXO Desk Study 2012 – Results HR3


Contamination of HR3 OWF development area. Green denotes contamination class B2,

yellow denotes contamination class B3 and red denotes contamination class B4.

UXO Desk Study 2012 – Results HR3


UXO risk levels for working on the seafloor in the HR3 area:

Western part: Direct and indirect seabed interactions (A2 – A4) can be performed within the

tolerable risk level (ALARP).

Eastern part (military exercise area): Direct seabed interactions (A3 and A4) in the eastern

part require risk mitigation. Indirect seabed interactions (A2)

can be performed within the tolerable risk level (ALARP).

Central part (danger zone on Nautical Chart):

All seabed interactions (A2 – A4) require risk mitigation.

Mitigation measures, examples

UXO HR3 and geotechnical investigations 2013

• It has been decided that the geotechnical contractor (Provider) is responsible

for carrying out necessary UXO survey and –evaluations before borehole

drilling, CPT testing etc. – on all locations within OWF HR3. Necessary:

Platform legs, anchors etc.

27-02-2013 9OWF Horns Rev 3 and Kriegers Flak - Geo Investigations

UXO Desk Study 2012 – Results KF


UXO Desk Study 2012 – Results KF – no threats!


UXO KF and geotechnical investigations 2013

• It has been decided that there is no requirement to carry out UXO survey

within OWF KF prior to performing boreholes etc.

27-02-2013 12OWF Horns Rev 3 and Kriegers Flak - Geo Investigations

27 February 2013 13OWF HORNS REV 3 AND KRIEGERS FLAK

Offshore Wind Farms

Horns Rev 3 and Kriegers Flak

Geo Investigations 2012-2013

Preliminary Geotechnical investigations

Planned program

Main purposes of the geotechnical investigation

• Verify the geological units found, mapped and preliminary interpreted during

the geophysical survey in 2012 down to below the expected foundation depths

of wind turbines

• Characterise these geological units in geological and geotechnical terms, and

obtain geotechnical data and parameters for the observed soils and layers

• Correlate the geotechnical and geological results with interpreted geophysical

results for detailed delineation of sub-seabed sediment types and layers

• Verify geophysically found/indicated possible accumulations of shallow gas,

buried channels, soft sediments, etc.

• Be able to adjust the preliminary 3D geological model based upon the

geophysical survey results


Horns Rev 3 – Site specific focus points

In planning of the positions of the geotechnical investigation the following focus

points have been identified from the geophysical survey:

• Variations and organic layers in the Holocene sediments

• Possible presence of soft sediments in local channels in the Holecene Fresh

Water Unit

• Soft and/or organic sediments in the Horns Rev Valley

• Variations and organic layers in the Eemian sediments

• Variations with depth of the till in the Saalian glacial Unit, especially in the

westernmost part of the area, where the unit is high lying


Horns Rev 3– Geotechnical challenges

The following geotechnical challenges in relation to Wind Turbine installation

have been identified:

• The high lying till (in the westernmost part of the area) might have a high

content of stones and boulders

• Soft sediments in the Horns Rev Valley and locally in the Holocene sediments


Kriegers Flak – Site specific focus points

In planning of the positions of the geotechnical investigation the following focus

points have been identified from the geophysical survey:

• Variations in the Holocene sediments

• Possible presence of the Kriegers Flak Clay in the upper till

• Variations with depth of the upper and lower till

• Sediments in the channels in the limestone surface

• Variations with depth of the limestone, especially in areas with high lying

limestone and below channels


Kriegers Flak – Geotechnical challenges

The following geotechnical challenges in relation to wind turbine installation

have been identified:

• Stones and boulders might be present at seabed

• The till might have a high content of stones and boulders

• The lower till might be very hard and "rock-like"

• The limestone might contain layers of chert (flint)


Preliminary geotechnical investigations.Planned field program

The planned scope of field investigations at each of the sites Horns Rev 3 and

Kriegers Flak includes:

12 – 15 Boreholes

• depth of 50 m below seabed

• extraction of intact and disturbed samples

12 – 15 Continuous Cone Penetration Tests (CPT)

• placed adjacent to each borehole

• depth of 50 m below seabed

• If refusal of continuous CPT: Optional down the hole CPT in adjacent borehole

or blind drilling for continuous CPT depending on the soil conditions


Preliminary geotechnical investigations. Planned field program

The exact locations for the boreholes/CPT have not been defined yet, but will be

distributed within the areas to examine the various geological conditions.

Final locations will be decided when the final results of the geophysical survey

2012 is available.



Preliminary geotechnical investigations. Example of locations of boreholes/CPT.Horns Rev 3

Map: Base Eemian Marine

Borehole and CPT

Preliminary geotechnical investigations. Example of locations of boreholes/CPT.Kriegers Flak


Map: Lower Till / Top of Cretaceous Chalk

Borehole and CPT

Preliminary geotechnical investigations.Planned program - Laboratory tests

The planned scope of laboratory tests at each of the sites Horns Rev 3 and

Krigers Flak will include:

• Geological description and classification of soil and rock

- and the below listed classification tests as appropriate:

• Water content

• Bulk density

• Grain size distribution

• Atterberg limits

• Particle density

• Density index of granular soils (emin / emax)

• Loss of ignition




Krigers Flak will include the below listed chemical tests as appropriate:

• Chloride content

• Content of CaCO3

• Sulphate content




Krigers Flak will include the below listed special laboratory tests as

appropriate:

• Thermal resistivity (samples near seabed)

• Oedometer test

• Unconsolidated Undrained (UU) triaxial test

• Consolidated Undrained (CU) triaxial test

• Consolidated Drained (CD) triaxial test

• Unconfined Compression test


Preliminary Geotechnical investigations. Geotechnical Reporting and digital deliverables

Geotechnical reporting:

The results of the geotechnical investigation will be presented in a

Factual Geotechnical Report for each of the investigation areas.

Digital deliverables:

The data results of the geotechnical investigation will be delivered in AGS-

format.


Preliminary Geotechnical investigationReporting – Factual Geotechnical Report


The Factual Geotechnical Reports will include:

• Introduction and scope of Report

• Field operation

• Factual results

• Geotechnical boreholes

• CPT results – measured data and calculated values

• Laboratory tests

• Soil conditions

• Geological overview

• Description of found results

• Presentation of typical geotechnical characteristics

Preliminary Geotechnical investigations.Reporting – Factual Geotechnical Report


Enclosures to Factual Geotechnical Reports will include:

• General and detailed location plan with test locations

• Legends of definition

• Borehole profiles including geological description and laboratory tests results

• CPT profiles, including measured, calculated data and soil profile

• Laboratory test results

• Summary tables for boreholes, CPT´s and laboratory tests

• Photos of samples

Preliminary Geotechnical investigations.Reporting – Example CPT Results


Preliminary Geotechnical investigations.Reporting – Example Borehole profile



Offshore Wind Farms

Horns Rev 3 and Kriegers Flak

Geo Investigations 2012-2013

Preliminary Geotechnical investigations

Planned / Considered program


Geotechnical 2013 – Planned / Considered Program

Additional initiatives other than the geotechnical borehole / CPT programme:

1. Acoustic CorerTM, especially at Kriegers, Flak to locate and quantify possible

occurrences of boulders (and other shallow geohazards)

2. Adjustment of the 3D stratigraphical model from Geophysical 2012 with the

lithological, and interpreted, data from boreholes/CPTs

3. A synopsis of the different geo reports into a Preliminary Geoengineering report


Acoustic CorerTM

Acoustic CorerTM pre-investigations with the following objectives:

• Complete information for the identification of significant acoustic anomalies,

consistent with geohazards ≥0.5m diameter such as buried objects and boulders.

• Complete information for the identification of shallow gas located within the Core.

• Comprehensive description of the sediment stratigraphic column in step with the

acoustic impedance contrasts that exist in the transition between the layers.

• Correlations between borehole/CPT data and between the acoustic core data

• A statistical analysis of significant acoustic anomalies with respect to anomaly

size, anomaly depth of burial, and with which geological unit the anomalies are

associated e.g. number of boulders per unit volume, size distribution of boulders.

• The objectives being to provide the potential Bidder with information by

which they can determine areas within the wind farm that pose the most

risk to piling operations. Buried objects and boulders present a considerable

potential cost and schedule risk during the installation of offshore infrastructure.

• Proposed amount of Acoustic CoresTM: c. 15 at Kriegers Flak and c. 5 at Horns Rev 3

• Relatively expensive – less than, but in the order of a borehole


Acoustic CorerTM

• The Acoustic Corer™ 3D technology uses multi-aspect acoustic intensity imaging

to delineate sub seabed stratigraphy and buried geohazards such as boulders,

hard layers, shallow gas, and abandoned seabed infrastructure.

• The Acoustic Corer™ unit consists of two sonar heads attached to each arm of the

12m boom. This boom rotates 180° thereby creating a 360° acoustic core.

• Every measurement lasts c. 24 hours, once the equipment is positioned on the

seabed, and has a penetration of up to 30m (most effective in the upper 12m)


A substantially larger ”diameter” than a borehole


Acoustic CorerTM


Update the 3D geological model with borehole/CPT data

• Based on the seismic results from the Geophysical survey in 2012 a 3D stratigraphic

Geological Model is constructed in Kingdom Suite.

• It is considered to update and adjust this digital model with the geological/lithological,

and interpreted, results from the planned boreholes and CPTs (and possibly Acoustic

Corers) into a preliminary Geotechnical Model that will be part of the Delivery.

• It is the intention, that this preliminary Geotechnical Model after the pre-investigations

will form the basis for further developments and refinements into a more detailed

Geotechnical Model and eventually into an Engineering Model based on additional

geophysical and geotechnical site investigations.


Preliminary Geoengineering Report

Note that the outcome of Geophysical 2012 and Geotechnical 2013, including possible

Acoustic CorersTM 2013, will be:

• Raw, Processed and Interpreted Data

• Reports, Profiles, Digital Models, Charts and Maps

• Everything primarily of a ”Factual” character

We suggest a Preliminary Geoengineering Report to be prepared as part of the

Final Delivery, including an updated 3D Geotechnical Model (see previous slide): The

character of this Preliminary Geoengineering Report is planned to be:

• A synopsis of the results from the geo pre-investigations, including UXO

• An integrated/interpretative/conclusive geoengineering report

• A technical ”executive” report

The time frame for the Preliminary Geoengineering Report will have the same final

deadline as the EIA does: end of March 2014.

.

HR3 & KF Geo Investigations UXO Desk Study 2012 · PDF fileHR3 & KF Geo Investigations UXO Desk Study 2012. UXO ... where the unit is high lying 27 ... 27 February 2013 OWF HORNS...

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