soil resistivity analysis -borssele woz v1.1 - table of ... · soil resistivity which will only be...

POSITION PAPER

STAKE HOLDER CONSULTATION PROCESS OFFSHORE GRID NL

Type: Position paper

Work stream Technical

Topic: T.11 Overplanting

Filename ONL 15-083-T11_Overplanting_PP_v3

Version 3 - Public release

Pages 14

QUALITY CONTROL

Prepared: Daniël Vree

Reviewed: Frank de Vries 29.02.2016

Approved: Frank Wester 29.02.2016

Release

Table of Contents

1. BACKGROUND MATERIAL ......................................................................................................................... 2

2. SCOPE AND CONSIDERATIONS................................................................................................................ 2

3. ACTIVE POWER TRANSFER THROUGH THE TENNET OFFSHORE GRID ............................................ 4

3.1 Export cable design (220kV) (Status V1, dd 10-04-2015) .................................................................. 4

4. ADDITIONAL CALCULATIONS ON DYNAMIC LOADING OF THE EXPORT CABLES ........................... 5

4.1 Introduction (V2 – 13-10-2015) ........................................................................................................... 5

4.2 Update 01 - 29-2-2016 - based on results of initial geotechnical survey (V3) .................................... 6

Analysis of soil data of the initial geotechnical survey ......................................................................................................... 6

Update of the dynamic ampacity calculations for 380MW: basis for the calculations ........................................................... 7

Update of the dynamic ampacity calculations for 380MW: calculations results .................................................................. 10

5. EXPORT CABLE LOAD MANAGEMENT .................................................................................................. 11

6. POSITION OF TENNET .............................................................................................................................. 12

7. IMPACT ON COST ..................................................................................................................................... 13

8. FURTHER UPDATES (STATUS AS OF 29-2-2016) .................................................................................. 13

9. ANNEX A: SOIL RESISTIVITY ANALYSIS - OFFSHORE CABLE ROUTE FROM LANDFALL TO

BORSSELE ALPHA AND BETA ........................................................................................................... 14

Disclaimer: the content of this paper is disclosed for information purposes only. In no way does this paper constitute rights for

(potential) Connected Parties, or bind TenneT legally.

TenneT TSO B.V.

DATE 01.03.2016

PAGE 2 of 14

1. Background material

Literature used:

N.A.

2. Scope and considerations

The Figure 1 below shows a schematic cross section of the connection of an offshore wind farm to the

onshore electricity grid. Wind turbines are connected through “inter-array” cables (in orange) to the offshore

Connection Point (CP)1 at the offshore substation, from which electricity is transported to shore. TenneT is

responsible for the grid connection up to, and including, the offshore substation and will take care for the

supply and installation.

The wind park, including the wind turbines and the array cables, up to the offshore CP at the switchgear

installation on the offshore substation of TenneT, is to be supplied and installed by the owner of the Power

Park Module (PPM2).

TenneT intends to standardise the offshore substations as much as possible for all five wind areas to be

realised in the coming years in line with the Energy Agreement.

Figure 1 - Schematic of the offshore electrical grid. Source: TenneT

1 The connection point (CP) between the offshore power park module (PPM) and TenneT is specified [TenneT position

paper ONL 15-061 T.3 Point of Common Coupling] at the cable termination of the inter-array cables and the switchgear installation on the platform. 2 TenneT, position paper ONL 15-079 T.5 Operation of Bays



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DATE 01.03.2016

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Overplanting

An important aspect in the design of an offshore wind farm, is to optimise the offshore wind farm capacity

(type and number of wind turbine generators) to the fixed electrical infrastructure export capacity. This

principle is also referred to as overplanting or overbooking since it usually leads to installing a (small)

number of extra wind turbine generators compared to the grid connection capacity limit3. The "overplanted"

power from these extra turbines will result in higher energy yield at lower wind speeds but will lead to a

curtailed power at higher wind speeds as depicted in Figure 2. Off course, the extra turbines will result in

higher CAPEX, which should be balanced by extra revenues from the extra energy yield.

Figure 2 - Principal of Capacity Optimisation. Source: Global Offshore Wind Conference 2014.

To be able to further optimise the PPM lay-out (location, type and number of wind turbine generators), it is

necessary for the PPM owner not only to know to what to extent the grid connection may be continuously

loaded (e.g. the grid capacity limit) but also to what extent the grid connection may be (temporary) loaded

above this capacity limit. In this way, the curtailed power is reduced and the energy yield is increased further.

This paper describes the position of TenneT with respect to the extent to which the offshore grid (see Figure

1) may be loaded more than the rated power at CP and under which conditions. As the limiting factor in the

offshore grid is the 220 kV export cable from the offshore substation up to and including the beach landing,

this paper will mainly focus on these cables.

3 Money does grow on turbines – Overplanting Offshore Windfarms, Andrew Henderson a.o., Global

Offshore Wind Conference 2014



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DATE 01.03.2016

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3. Active power transfer through the TenneT offshore grid

The offshore grid design will be based on the parameters as listed in Table 1.

Table 1 - TenneT NL offshore grid parameters

Grid parameter Value

Grid capacity per PPM at offshore CP: 350MW

Number of PPM per offshore platform: 2

Reactive power exchange at CP under normal conditions: Max +/- 0,1 p.u. (+/- 35 Mvar)

Nominal voltage level onshore / offshore: 225 / 230kV +/- 1%

To determine if more than 700MW (2 * 350MW) of active power (P) can be transferred through the offshore

grid, TenneT makes an assessment of the capability of the 220 kV export cables (next paragraph) based on

the parameters shown above. If there is additional capacity found in the design which allows the 220 kV

export cables to transfer more than 700MW of active power, TenneT will assure that other grid components

will also be capable to transfer this extra power.

According to RfG, PPMs will be required to contribute to the primary voltage regulation with more reactive

power than shown in Table 1. It is assumed that these circumstances (Q > 35Mvar or Q < -35Mvar) will be

limited in time and therefore will not significantly influence the thermal loading of the cables.

3.1 Export cable design (220kV) (Status V1, dd 10-04-2015)

A preliminary 220 kV export cable design study was commissioned by TenneT for a capacity of 700MW in

steady state condition according to the IEC 60287. Although the exact soil conditions are not yet known, the

results of this design show that under a wide range of the thermal resistivity of the soil, typical cable designs

are available.

Furthermore, within this study dynamic load calculations on the 220 kV export cables have been performed

using actual wind data over a measuring period of three and a half years. The calculations have been used

to assess possibilities for optimisation of cable dimensioning. The calculations are based on various cable

types (variation in conductor type and cross section), a range of thermal resistivity values of the soil and two

different installation locations (near offshore platform at one meter under seabed and near shore at three

meters under seabed).

The results of the dynamic load calculations show that for an optimized cable design (at 700MW design

capacity), the transmission of 10% additional active power is allowable, but not guaranteed, provided the

following conditions are met:

- Voltage at nominal voltage as defined in Table 1;

- Soil resistivity over the whole trajectory 0,7 K.m/W as a maximum

Simulation results show that on a few occasions the maximum allowable conductor temperature would be

exceeded and curtailment is necessary (provided that all wind turbine generators are in operation). These



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DATE 01.03.2016

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results are shown in Figure 3. Further analysis of these results show that from the 30.000 simulated hours,

the conductor temperature is 643 hours above 90 °C (2,14%).

A more detailed forecast on risk of curtailment will be made by TenneT when soil conditions are known and

the basic design of the cable is available.

Figure 3 - Thermal behaviour of one of the 220 kV export cables (preliminary design) at two thermal resistivity values at the beach with a wind farm installed power of 770MW.

4. Additional calculations on dynamic loading of the export cables

4.1 Introduction (V2 – 13-10-2015)

The duration in hours that a load of 380MW can be transferred through one of the export cables before

curtailing of output power of the wind park will take place is dependent on the following factors:

1. Temperature of the cable before the 380MW limit is reached. This temperature is again

dependent on the loading history of the cable the previous hours or even days. This again is

directly related to the wind speed;

2. The method of curtailing of which preliminary information is given below;

3. Final soil resistivity values over the complete cable route;

4. Final design of the cable system;

5. Voltage level of the system.

A clear and binding answer on the question of duration before curtailing will occur can't be given due to e.g.

soil resistivity which will only be determined on a limited set of samples and the power output of the wind

farms.



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DATE 01.03.2016

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However, TenneT made dynamic loading capability calculations based on assumptions on wind speeds, soil

resistivity and cable design. In this position paper and V14 some results of these calculations have been

given5.

When soil resistivity measurement results (which are part of the geotechnical survey) are available to

TenneT, TenneT will update its calculations for the Borssele case which will lead to a better estimate. This

update is expected to be finished end of January 2016. Within these calculations, the following calculations

will be made for the worst case location on the cable route (hot spot):

1. Time until the conductor reaches 90 °C at 380MW load with a starting conductor temperature

(t=0) related to a continuous loading of the cable before (t<0) of 350MW and 0MW;

2. Time until the conductor reaches 90 °C at 365MW load with a starting conductor temperature

(t=0) related to a continuous loading of the cable before (t<0) of 350MW and 0MW.

These simulation results (which are still estimates) can be used in the business case calculations of the

offshore wind park developers.

4.2 Update 01 - 29-2-2016 - based on results of initial geotechnical survey (V3)

Analysis of soil data of the initial geotechnical survey

In January 2016 the final report of the first geotechnical survey has been received by TenneT. The final

report ['Factual Report Geotechnical Investigation, 15-01-2016'] is available on request via

[email protected]. In this survey 115 boreholes are included with a target depth of seabed – 6m including

measurements of the thermal conductivity of 10cm samples per each 1m. Most boreholes ended between

seabed – 5m and seabed – 6m.

The raw data of this final survey report has been processed where for each borehole the effective thermal

resistivity value (G) has been determined on the target depth of burial (DOB) using the conformal mapping

methodology as stipulated in [Cigré ELECTRA nr 98, The calculation of the effective external thermal

resistance of cables laid in materials having different thermal resistivities, 1985]. These effective thermal

resistivity (G) values are included in Annex A. The target DOB per route section (which can also be found in

the table of Annex A) has preliminary been determined by TenneT based on expected permit requirements

and preliminary results of the morphological study and may change during the ongoing route engineering

works.

Based on the data of the final survey report and Annex A, the areas with the highest thermal resistivity

values have been listed in Table 2, where also a short description is included per area.

4 http://www.tennet.eu/nl/fileadmin/afbeeldingen/grid-projects/Net_iop_zee/Ronde_2/ONL_15-083-

T11_Overplanting_PP_v1.pdf 5 KNMI1 measuring pole 321 Europlatform (coordinates 10044; 447580), measuring dates 1-1-2001 until 3-

6-2004, data was converted from 29.1m height to a height of 107m.



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Table 2 – Areas with highest thermal resistivity values along the Borssele cable route

Location Target

DOB [m]

Effective G

[K.m/W]

Description

Mudflats 3 1,6 The thermal resistivity which is found in the mudflats area

is the result of layers of peat and clay. If the target DOB

would be decreased to 1,2m (land equivalent), the

effective resistivity value will decrease to 1,3 K.m/W.

Spijkerplaat 20 0,7 At this moment, an estimate of the effective thermal

resistivity on 20 meters has been assumed. Although the

target DOB in the Spijkerplaat is now preliminary set at

10m, the morphological study indicates that in the future a

coverage up to 20m can be expected and this value has

to be taken into account in the cable design.

Rede van

Vlissingen

6 0,8 At KP11-KP13 layers of clay have been identified at the

southern part of the cable route. Only limited

measurements are available (on route BH92 and off-route

BH111, BH112), but based on these measurements, clay

must be taken into account which results in the given

thermal resistivity value.

West of Botkil 1 0,9 In this area clayey soil has been found.

Offshore below

sand wave

8 0,5 Based on the current survey data, effective thermal

resistivity on the bottom of the sand wave is estimated to

be 0,5 [K.m/W]. Due to the migration of sand waves and

as the cables will be installed at a level below the bottom

of these sand waves, cables may in the future be covered

by a full sand wave with heights up to 8m.

The areas of Table 2 are shown on a map in Figure 4.

Figure 4 – Locations of Table 2 on the map

Mudflats

West slope of Rede van

Vlissingen

West of Botkil



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DATE 01.03.2016

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Update of the dynamic ampacity calculations for 380MW6: basis for the calculations

Soil conditions

In the previous issue of this position paper the following assumption was made on the thermal resistivity

along the cable route:

- Thermal resistivity over the whole trajectory 0,7 K.m/W as a maximum

From Table 2 it can be concluded that this is not the case in three of the areas (Mudflats, Rede van

Vlissingen, West of Botkil). Also the future coverage of 20 meters at the Spijkerplaat was not taken into

account at that time. Below it is described how the new results are taken into account in the basis for the

dynamic ampacity calculations of this update.

As currently a) cable/route engineering is still in progress and b) an additional survey is being carried out,

this basis for calculation may change significantly. Therefore, this update is only an intermediate update

where in some cases no calculations have been done (Mudflats) or calculations for two different scenario's

(Spijkerplaat / Rede van Vlissingen). See chapter 8 on when the final update will become available.

Mudflats: The thermal resistivity of the mudflats area is so high that backfill must be considered. Backfill is a

mitigating measure where thermal resistivity is improved by embedding the cable in sand with a better

thermal resistivity value than the original soil. At this moment, the feasibility of this option is under

investigation., both technically as permit wise. Therefore, this area has not been taken into account within

this update of the dynamic ampacity calculations, but will be taken into account in the final update. However,

at this moment it is expected that with the right backfill design, ampacity issues can be mitigated.

Spijkerplaat: The value in Table 2 of the effective thermal resistivity of the extreme future burial condition at

the Spijkerplaat of 20 meters has been used as the basis for the dynamic ampacity calculations of this

update. When results of the current survey (see chapter 8) will become available, the effective thermal

resistivity value for this case will be calculated from actual soil measurements and may then change

significantly. Therefore, the results of the calculations on this area must be treated as preliminary. As an

example, also calculations for an effective thermal resistivity of 0,6 K.m/W have been made.

Rede van Vlissingen: At the areas where clay has been found, the target DOB will be decreased to the

minimum DOB required by permit which is seabed – 3m for this area. For this area both of the following

cases have been used as a basis for the dynamic ampacity calculations:

- DOB of 6m with effective G-value of 0,8 [K.m/W] (original case of Table 2)

- DOB of 3m with effective G-value of 0,7 [K.m/W] (case with following assumptions: a) DOB is

decreased, b) trench will be dredged and c) sand will be used for filling the dredged trench).

West of Botkil / sand waves: For the offshore part of the cables the West of Botkil area was determined to

be the worst case situation based on the (static) ampacity calculations for 350MW and has been used for

this update of the dynamic ampacity calculations.

6 In V3 of this position paper, the maximum power of 380 MW is aligned with the development framework for

the offshore grid as prescribed by the Ministry of Economic Affairs



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The above scenario's are summarized in Table 3.

Table 3 - Calculation scenario's used for update 01 of the dynamic ampacity calculations

West of Botkil Rede van Vlissingen Spijkerplaat

DOB = 1m DOB = 3m DOB = 6m DOB = 20m

G = 0,9 G = 0,7 G = 0,8 G=0,6 G = 0,7

Scenario 380.1 Scenario 380.2 Scenario 380.3 Scenario 380.4 Scenario 380.5

Cable design

Load Flow

For cable properties which have an impact on the load flow, following values have been assumed for the

dynamic ampacity calculations of this update:

- Capacitance of cable: 0,22 µF / km (mean value)

- Length of cable: 67 km (Borssele Beta, worst case)

This results in a full load current (350 MW) at the land station side of 925A and an overload current (380

MW) of 1000 A. Also, an additional preloading condition of 67% has been taken into account of 710 A7.

Variance of capacitance will lead to a variance of full load current (350 MW) in the range of 15A around the

above stated current of 925 A. For Borssele Alpha with a route which is 7km less, the full load current (350

MW) will be reduced with about 10A.

The reactive power compensation at full load is assumed to be 50%/50% onshore and offshore. The

reduction of capacitive current in the cable further from platform or land station has not been taken into

account in the dynamic ampacity calculations of this update.

Losses

In the previous versions of this position paper (V1 / V2), the provided calculation results were based on a

general and preliminary 1600mm2 AL (aluminium) conductor cable design not related to any specific cable

manufacturer.

In this update of the dynamic ampacity calculations, the same 1600mm2 AL cable design is used as a base

case. If static ampacity calculations on 350MW showed that this design would not reach the required static

ampacity, a general and preliminary 1600mm2 CU (Copper) cable design has been used instead.

For both designs, on other cable properties which have an impact on the losses (apart from conductor

design), following assumptions have been used:

- Armour design: galvanized steel wires with λ2 factor according to IEC 60278 (worst case);

- Cable (core) lead sheath: common value for thickness of the sheath and λ1 factor according to IEC

60278 (average value)

7 This current is higher than 67% * 925 A as at lower currents, the 50%/50% compensation scheme is

shifting towards a higher current at land station side. This higher current in the loadflow has been used here.



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DATE 01.03.2016

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J-tube

The J-tube is not found to be a critical part of the cable system. With the base case of 1600mm2 AL, the

steady state rated current in the J-tube is well above 1000 A. This is based on the following conditions:

- Wind speed of > 10 m/s;

- Solar radiation of 602 W/m2 (max intensity of 1000 W/m2 and an angle of 53°);

- Ambient temperature of 30 °C.

Grid connection limitations

With respect to the overloading of the grid connection system, the 380 MW shall be seen as an absolute

maximum as other grid components such as the main transformers have much shorter thermal time

constants. If more than 380 MW is being generated by the WPO, the curtailment level 3 is applicable as

described in chapter 5 (actual curtailment of the power output of the wind park by TenneT). In this case a

certain time delay will be taken into account which will be related to the amount of exceedance of the 380

MW limit.

Update of the dynamic ampacity calculations for 380MW: calculations results

In V2 of the position paper, following was stated (see paragraph 4.1):

Within these calculations, the following calculations will be made for the worst case location on the cable

route (hot spot):

1. Time until the conductor reaches 90 °C at 380MW load with a starting conductor temperature (t=0)

related to a continuous loading of the cable before (t<0) of 350MW and 0MW;

2. Time until the conductor reaches 90 °C at 365MW load with a starting conductor temperature (t=0)

related to a continuous loading of the cable before (t<0) of 350MW and 0MW

In this update of the dynamic calculations, only the 380MW case has been studied, but five scenario's

instead of one scenario have been assessed as well as three different preloading conditions (instead of two).

The preloading condition of 67% / 710 A has been added to reflect an average loading of the cable which

may be expected over a long time with a wind farm loading profile. Also, a preloading time of one year has

been used for the 67% and 100% conditions to assure a starting temperature which is nearby the steady

state conductor temperature when calculated according the IEC 60267. The dynamic calculations for this

update have been made according to the IEC 60853.



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The results of the calculations are given in Table 4 where the time until the conductor reaches 90 °C is

stated in hours.

Table 4 - Time (in hours) for conductor to reach 90 °C at 1000 A with three preloading conditions for five scenario's

Preloading Time to reach 90°C [hours]

% # of days

Preload I [A]

Scenario 380.1

Scenario 380.2

Scenario 380.3

Scenario 380.4

Scenario 380.5

0% n/a 0 1100 2350 4440 > 8760 >8760

67% 365 710 520 920 1920 4500 4900

100% 365 925 65 25 95 3700 4250

West of Botkil Rede van Vlissingen Spijkerplaat

DOB = 1m DOB = 3m DOB = 6m DOB = 20m

G = 0,9 G = 0,7 G = 0,8 G=0,6 G = 0,7

For the scenario's following conditions have been used:

- Scenario 3 and 5: 1600mm2 CU conductor

- Scenario 1, 2 and 4: 1600mm2 AL conductor

- Scenario 1, 2: ambient temperature 15 °C

- Scenario 3, 4,5: ambient temperature 10 °C

- Overloading: 380MW, Current I [A]: 1000 A

5. Export cable load management

In general, TenneT identifies three levels in the export cable load management process:

1. Alignment of the wind park owner's (WPO) generation forecasts to dynamic cable loading

capabilities;

2. Actual curtailment of the power output of the wind park by the WPO;

3. Actual curtailment of the power output of the wind park by TenneT.

Ad 1

It is the responsibility of the WPO to align its forecasts to possible curtailment of the wind park power output

due to the temperature limit of the export cables (only if wind park power output is higher than the

guaranteed 350 MW). To facilitate this alignment process, TenneT will provide:

a) calculation results as described above (updated on the as-built situation);

b) the actual cable conductor temperature measurements (data format and frequency to be defined in a

later stage).



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DATE 01.03.2016

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Ad 2

If the conductor temperature will increase above a certain threshold value (value to be determined per

project), WPO will receive a warning signal from TenneT. WPO shall start at that moment (at the latest) with

the curtailment of the wind park power output, down to 350MW. If this curtailment is not started or is not

sufficient and conductor temperature will increase above a second threshold value (close to but below 90

degrees Celsius, to be determined per project), WPO will receive a second and final warning signal from

TenneT. Immediately after this second signal has been released, TenneT has the right to proceed to the

third level as described below.

The warning signals are considered to be the official legally binding information provided by TenneT to the

WPO. The cable conductor temperature measurements as described under level 1 are provided by TenneT

as an extra service and will be for information only.

Ad 3

When the second warning signal has been released, WPO shall immediately reduce the power output to a

maximum of 350 MW. TenneT will at that time monitor conductor temperature and power output

continuously. If the reduction of power by the WPO is not sufficient, TenneT will have the right to curtail

under 350MW by switching off one of the strings of the wind park without any further notice.

With the three levels described above, an export cable load management process has been introduced that

enables the WPO to manage its generation forecasts and actual power output curtailment while at the other

hand it is assured that the export cable conductor temperature will never increase above 90 degrees Celsius.

6. Position of TenneT

Above considerations lead TenneT to the following position:

TenneT is inclined towards allowing the PPMs to transmit 8% above their rated power (350MW), which is

30MW extra, with the requirement for PPM's to curtail their produced power, in case the 220 kV export

cables reach their maximum allowable temperature limits8. Details on curtailment of the PPMs will be

addressed to in the 'Customer Connection Agreements (ATO)'.

The calculations results of paragraph 4.2 are only valid for Borssele. For the Hollandse Kust (Zuid) tender,

TenneT will give an update based on specific Hollandse Kust (Zuid) soil data.

TenneT has decreased the allowed additional rated power from 10% (V2) to 8% (V3) in order to align this

allowable addition with the development framework for the offshore grid as prescribed by the Ministry of

Economic Affairs.

8 Operational limits of sea and land cables will be monitored continuously by temperature sensing systems.



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DATE 01.03.2016

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7. Impact on cost

At this point in time the impact on costs cannot be analysed quantitatively, as this requires detailed

knowledge (assumptions) on both wind farm layout, turbine choice and dynamic loading strategies.

8. Further updates (status as of 29-2-2016)

At this moment a second survey is being carried out for additional information on thermal resistivity due to

the following reasons:

- Determination of thermal resistivity in highly mobile areas (Spijkerplaat, Nollenplaat) up to a depth

of 10m (Nollenplaat) and 20m (Spijkerplaat);

- Better assessment of the other areas listed in Table 2: West of Botkil and Rede van Vlissingen.

The results of this additional survey will be used for a final update of this position paper. Also, 365 MW

scenario's will be included in that update.

This update is expected first half of April 2016.



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DATE 01.03.2016

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9. Annex A: Soil resistivity analysis - Offshore cable route from landfall to Borssele Alpha and Beta

Table with effective soil resistivity values.

From KP

Subsection to KP

km km m

1 Northern slope Honte 0,7 1,3 North slope Honte to shore 0.0 – 0.9 0.9

3 118-PC 549956.00 5697186.00 1,39 Conformal mapping



3 117-PC 549883.16 5696856.43 0,44 Average <3m

2 Honte Navigational Channel 1,3 1,8 Honte fairway 0.9 – 1.9 1.0

3 107-VC 549764.03 5696667.24 0,70 Average. Meas <2,2m

3 068-VC 549498.16 5696510.96 0,70 Average. Meas <1,5m

3 067-VC 548912.50 5696420.94 0,45 Conformal mapping

3 108-VC 549946.33 5696164.71 Offroute but possibly required 0,65 Average. Meas <1,7m


3 Southern slope Honte 1,8 3,0 Slope fairway to Spijkerplaat -10m 1.9 – 2.1 0.2

3 548789.16 5696147.39 0,53 Conformal mapping

4 Spijkerplaat 3,0 6,1 Spijkerplaat from LAT-10m to -10m 2.1 – 7.2 5.1

10066A-VC 548257.15 5696550.36 Effective G value on 5m 0,45

Average < 5,3 m,

No samples>5m

10076a-PC 547943.23 5696295.28 Effective G value on 6m 0,48

Average < 5,6 m,

No samples>5m

10074-VC 547814.26 5696703.89 Effective G value on 6m 0,43

Average < 5,0 m,

No samples>5m

10 077-VC 547429.76 5696837.87 Effective G value on 6m 0,49 Conformal mapping

10102-PC 547022.55 5696652.40 Effective G value on 6m 0,45

Average < 5,6 m,

No samples>5m


Average < 5,6 m,

No samples>5m

10104b-PC 545400.45 5696717.95

Offroute but possibly required

Effective G value on 6m 0,45

Average < 5,6 m,

No samples>5m

10101b-PC 545094.14 5697228.25 Effective G value on 6m 0,50

Average < 5,6 m,

No samples>5m


Average < 5,6 m,

No samples>5m

5 Rede van Vlissingen 6,1 11,6 Between LAT-10m Spijkerplaat to Rede v. Vl. 7.2 – 9.0 1.8

10 543990.29 5697417.09 0,46 No samples > 5m

6 Rede van Vlissingen 6,1 11,6 Rede van Vlissingen 9.0 – 11.6 2.6

6 060-VC 542891.71 5697226.06 0,43 Average

6 059-VC 541813.88 5697751.01 0,46 Average

6 113-VC 541268.97 5696916.24 0,45 Average


7

Navigational channel

Westerschelde /

South of Nollenplaat

11,6 13,6 Remainder west slope Rede v.Vlis-Nolleplaat 11.6 – 15.1 3.5

6112-VC 539228.51 5696705.73 0,76 Conformal mapping




6 536687.17 5698369.90 0,44 Average

8 Nollenplaat 13,6 16,6 Nolleplaat 15.1 – 17.3 2.2


3 084-VC 536551.41 5699119.80 0,41 Average <4m

3 085a-VC 536405.16 5698977.96 0,40 Average <4m

3 086-VC 536162.09 5699016.28 0,41 Average <4m

3 052-VC 535938.79 5699344.50 0,41 Average <4m

9 Deurloo 16,6 27,8 Deurloo 17.3 – 27.2 9.9












3 529058.68 5705908.95 0,46 Average


10 Rassen 27,8 32,3 Rassen 27.2 – 32.0 4.8


6 527235.83 5708348.08 Effective G value for 3m 0,43 Average <2,9




11 Kaloo to LAT -10m 3) 32,3 35,6 Between Rassen and LAT-10 m 32.0 – 36.0 4.0





039-VC

038-VC

098-VC

037-VC

Section

044-VC

043-VC

042-VC

041-VC

040-VC

097-VC

047-VC

046-VC

045-VC

093-VC

Point-ID

Nearshore borehole locations

048-VC

051-VC

050-VC

049-VC

CommentThermal resistivity

[K.m/W]Remarks

054-VC

Easting Nording

053-VC

lengthDepth of

installation

087-VC

061-VC Effective G value on 5m

Borehole is off-route. It is not clear if layers of

clay extend to actual cable route

From KP

Subsection to KP

km km m

12 LAT -10m up to West Rond Route 3) 35,606 46,719 West of Botkil 36.0 – 38.0 2.0

1 521947.01 5713042.72 Layer of clay, 1,2 meter (0,2-1,4m) 0,83 Conformal mapping


1 094-VC 520481.48 5713958.33 No wet density samples analyzed n.n. Value at -1m

13 LAT -10m up to West Rond Route 3) East slope Steendiep 38.0 – 40.0 2.0

1 030-VC 519061.91 5714809.76 0,42 Value at -1m

1 029-VC 519740.71 5715113.18 0,54 Value at -1m

14 LAT -10m up to West Rond Route 3) Steendiep 40.0 – 44.5 4.5

1 028-VC 518879.13 5715371.74 0,50 Value at -1m

1

027-VC 517933.71 5716052.65

First layer (0,8m): sand with high resistivity

value (0,8). Data from DB/calculation, no

measurement 0,61 Conformal mapping

1 026-VC 516840.24 5715997.54 0,35 Value at -1m

1 025-VC 515861.69 5716128.57 0,47 Value at -1m

1 024-VC 515421.20 5716929.27 0,45 Value at -1m

1 099-VC 514952.57 5716837.77 0,32 Value at -1m

15 LAT -10m up to West Rond Route 3) Rabsbank 44.5 - 47.0 2.5

1 514695.41 5717455.07 On two depths (possibly sand wave) 0,56 Average of first 2 layers

3 514695.41 5717455.07 On two depths (possibly sand wave) 0,49 Conformal mapping

1 514627.34 5718465.32 On two depths (possibly sand wave) 0,45 Value at -1m

3 514627.34 5718465.32 On two depths (possibly sand wave) 0,42 Conformal mapping

1 022-VC 513909.68 5718446.19 0,37 Value at -1m

16 West Rond Route 3) 46,719 50,17 Shipping route over West-Rabsbank 47.0 – 50.0 3.0

1 513585.45 5719597.97 0,41 Value at -1m

1 512638.11 5720465.94 0,39 Value at -1m

1 512393.83 5721308.87 0,39 Value at -1m

17West Rond Route up to platform

location 3)50,17 67,469 West slope Rabsbank 50.0 – 51.5 1.5

1 018-VC 511344.77 5721611.89 0,51 Value at -1m

1 017-VC 510810.35 5722753.85 0,44 Value at -1m

1 016A-VC 510931.74 5722951.89 0,39 Value at -1m


location 3)Sandwave area 51.5 – 60.3 8.6

1 015-VC 510070.39 5723421.65 Bottom of sand wave (-34,7) 0,49 Conformal mapping

1 095-Vca 509933.92 5724158.77 Bottom of sand wave (-33,8m) 0,55 Conformal mapping

1509266.07 5725289.54 0,38

Average <2,5m

No meas >-2,5,

3509266.07 5725289.54 On two depths; In between sand wave 0,38

Average <4m

No meas >-2,5,

1 508297.45 5725687.21 0,43 Value at -1m


1 507893.91 5726132.24 0,45 Value at -1m

3 507893.91 5726132.24 0,41 Average <3,6m

1507002.81 5726337.26 0,40

Average<2m

No meas.<-2m

3507002.81 5726337.26 0,40

Average<2m

No meas.<-2m

1 011-VC 506408.01 5727054.33 0,34 Value at -1m

1 010-VC 505351.27 5726877.48 0,41 Value at -1m

1 504755.38 5727377.24 0,37 Average <2,5m

1,5 504755.38 5727377.24 0,37 Average <2,5m


location 3)Buitenbanken 60.1 – 61.2 1.1

1 503624.93 5728130.83 0,40 Average <2,5m

4,5503624.93 5728130.83 0,42

Average <3,5m

No meas <-3,5 m

1 503638.08 5728352.16 0,45 Average <2,8m

3 503638.08 5728352.16 0,45 Average <2,8m


location 3)Sandwave area 61.32– 67.2 5.9

1 502304.13 5728536.81 0,48 Average of first 2 layers

1,5 502304.13 5728536.81 0,48 Average of first 2 layers

2,5 502304.13 5728536.81 0,58 Conformal mapping

1 501145.95 5729297.60 0,42 Value at -1m (one meas. disregarded)


1 500736.37 5729716.13 0,40 Value at -1m

3 500736.37 5729716.13 In between sand wave 0,40 Average <4m

1 499159.60 5730007.85 0,45 Value at -1m


1 002-VC 499065.86 5730276.24 Bottom of sand wave 0,40 Value at -1m

21Between platform Alpha and platform

Beta 3)67,469 67,469 Area just before Platform Beta 67.2 -67.4 0.2

1 497573.24 5731039.69 0,48 Average<3m

2 497573.24 5731039.69 In between sand wave 0,48 Average<3m

4 497573.24 5731039.69 In between sand wave 0,44 Average<4m

001-VC

021-VC

020-VC

019-VC

004-VC

008-VC

006-VC

003-VC

014-VC

096-VCa

009-VC

007-VC

Thermal resistivity

[K.m/W]Remarks

012-VCa

013-VCa

Easting Nording

073A-VC

023-VC

032-VC

On two depths; Top of sand wave. Depth

of hole only 2,15m though.

005-VC Near bottom of sand wave

Offshore borehole locations

lengthDepth of

installation Point-IDSection

On two depths; Near sand wave

On two depths; Near sand wave

In between sand wave (-25,5m)

Comment

Bottom of sand wave

In between sand wave (-24m)

Near bottom of sand wave

soil resistivity analysis -borssele woz v1.1 - table of ... · soil resistivity which will only be...

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