The Hornsea Four Offshore Wind Farm Order 2023

Detailed offshore design parameters E+W+S

3.—(1) The total number of offshore electrical installations and offshore accommodation platforms must not exceed ten, consisting of a combination of no more than—

(a) six small offshore transformer substations;

(b) three large offshore transformer substations;

(c) three offshore HVAC booster stations;

(d) six small offshore HVDC converter stations;

(e) three large offshore HVDC converter stations; and

(f) one offshore accommodation platform.

(2) The dimensions of any small offshore transformer substation (including auxiliary structures, such as a helipad, crane, lightning protection, but excluding masts, radar and antennae) forming part of the authorised project must not exceed—

(a) 100 metres in height when measured from LAT;

(b) 90 metres in length; and

(c) 90 metres in width.

(3) The dimensions of any large offshore transformer substation (including auxiliary structures, such as a helipad, crane, lightning protection, but excluding masts, radar and antennae) forming part of the authorised project must not exceed—

(a) 100 metres in height when measured from LAT;

(b) 180 metres in length; and

(c) 90 metres in width.

(4) The dimensions of any offshore HVAC booster station (including auxiliary structures, such as a helipad, crane, lightning protection, but excluding masts, radar and antennae) forming part of the authorised project must not exceed—

(a) 100 metres in height when measured from LAT;

(b) 90 metres in length; and

(c) 90 metres in width.

(5) The dimensions of any small offshore HVDC converter substation (including auxiliary structures, such as a helipad, crane, lightning protection, but excluding masts, radar and antennae) forming part of the authorised project must not exceed—

(a) 90 metres in height when measured from LAT;

(b) 100 metres in length; and

(c) 100 metres in width.

(6) The dimensions of any large offshore HVDC converter substation (including auxiliary structures, such as a helipad, crane, lightning protection, but excluding masts, radar and antennae) forming part of the authorised project must not exceed—

(a) 100 metres in height when measured from LAT;

(b) 180 metres in length; and

(c) 90 metres in width.

(7) The dimensions of any offshore accommodation platform forming part of the authorised project must not exceed—

(a) 64 metres in height when measured from LAT;

(b) 60 metres in length; and

(c) 60 metres in width.

(8) Offshore accommodation platform foundation structures forming part of the authorised project must be one of either monopile foundations, mono suction bucket foundations, gravity base structures, jacket foundations or box–type gravity base structures.

(9) Offshore electrical installation foundation structures forming part of the authorised project must be one of the following foundation options—

(a) for small offshore transformer substations and offshore HVAC booster stations either monopile foundations, mono suction bucket foundations, jacket foundations, gravity base structures or box–type gravity base structures; and

(b) for large offshore transformer substations and offshore HVDC converter stations either monopile foundations, mono suction bucket foundations, jacket foundations, box–type gravity base structures, gravity base structures, pontoon gravity base type 1 structures, or pontoon gravity base type 2 structures.

(10) No offshore electrical installation or offshore accommodation platform—

(a) jacket foundation employing pin piles forming part of the authorised project may—

(i) have a pin pile diameter of greater than four metres; and

(ii) employ more than 16 pin piles per jacket foundation; and

(b) monopile foundation forming part of the authorised project may have a diameter greater than 15 metres.

(11) The total seabed footprint area for offshore accommodation platform foundations must not exceed—

(a) 5,625 square metres excluding scour protection; and

(b) 30,625 square metres including scour protection.

(12) The total seabed footprint area for offshore electrical installation foundations must not exceed—

(a) 101,250 square metres excluding scour protection; and

(b) 371,250 square metres including scour protection.

(13) The total number of gravity base structures may not exceed ten for offshore electrical installations and offshore accommodation platforms.

(14) The offshore electrical installations and offshore accommodation platform comprised in the authorised project must be constructed in accordance with parameters set out in the pro–rata annex.

(15) A bridge link forming part of the authorised development must be installed at a minimum height of 20 metres when measured from LAT.

Commencement Information

I1 Sch. 1 Pt. 3 para. 3 in force at 3.8.2023, see art. 1