The Hornsea Two Offshore Wind Farm Order 2016

Foundation methods

4.—(1) The undertaker must in fixing to the seabed any structures comprised in Work Nos. 1A, 1B, 2A, 2B, 3A and 3B use one of the following methods—

(a) monopile foundations;

(b) jacket foundations supported by piles; or

(c) gravity base foundations.

(2) The undertaker must not use the monopile foundation method or any other method that includes braced monopiles to fix to the seabed any offshore HVDC converter substation.

(3) The following parameters apply in respect of the foundation methods used to fix wind turbine generators to the seabed—

(a) where monopile foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 1,963 square metres;

(ii) the diameter of each foundation must not exceed 10 metres;

(b) where jacket foundations (driven/drilled piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 2,827 square metres;

(ii) the number of piles per jacket must not exceed 12;

(iii) the diameter of each pile must not exceed 6 metres;

(c) where jacket foundations (suction piles) are used—

(i) the area occupied by the foundations and scour protection for each individual structure must not exceed 12,596 square metres;

(ii) the number of piles per jacket must not exceed 4;

(iii) the diameter of each pile must not exceed 21.1 metres;

(d) where gravity base foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 7,543 square metres;

(ii) the seabed levelling diameter must not exceed 78 metres;

(iii) the cone diameter must not exceed 58 metres at its base.

(4) The following parameters apply in respect of the foundation methods used to fix offshore accommodation platforms to the seabed—

(a) where monopile foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 1,963 square metres;

(ii) the diameter of each foundation must not exceed 10 metres;

(b) where jacket foundations (driven/drilled piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 1,414 square metres;

(ii) the number of piles must not exceed 8;

(iii) the diameter of each pile must not exceed 3 metres;

(c) where jacket foundations (suction piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 6,362 square metres;

(ii) the number of piles per jacket must not exceed 4;

(iii) the diameter of each pile must not exceed 15 metres;

(d) where gravity base foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 6,362 square metres;

(ii) the seabed levelling diameter must not exceed 70 metres;

(iii) the cone diameter must not exceed 50 metres at its base.

(5) The following parameters apply in respect of the foundation methods used to fix offshore HVAC collector substations to the seabed—

(a) where monopile foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 1,963 square metres;

(ii) the diameter of each foundation must not exceed 10 metres;

(b) where jacket foundations (driven/drilled piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 1,924 square metres;

(ii) the number of piles per jacket must not exceed 8;

(iii) the diameter of each pile must not exceed 3.5 metres;

(c) where jacket foundations (suction piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 12,723 square metres;

(ii) the number of piles per jacket must not exceed 8;

(iii) the diameter of each pile must not exceed 15 metres;

(d) where gravity base foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 6,362 square metres;

(ii) the seabed levelling diameter must not exceed 70 metres;

(iii) the cone diameter must not exceed 50 metres at its base.

(6) The following parameters apply in respect of the foundation methods used to fix offshore HVDC converter substations to the seabed—

(a) where jacket foundations (driven/drilled piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 17,318 square metres;

(ii) the number of jacket foundations per topside must not exceed 4;

(iii) the number of piles per topside must not exceed 72;

(iv) the number of piles per jacket must not exceed 18;

(v) the diameter of each pile must not exceed 3.5 metres;

(b) where jacket foundations (suction piles) are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 50,894 square metres;

(ii) the number of jacket foundations per topside must not exceed 4;

(iii) the number of piles per topside must not exceed 32;

(iv) the number of piles per jacket must not exceed 8;

(v) the diameter of each pile must not exceed 15 metres;

(c) where gravity base foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 27,300 square metres;

(ii) the number of pontoons for each individual structure must not exceed 3;

(iii) the pontoons must not exceed 170 metres in length or 35 metres in width.

(7) The following parameters apply in respect of the foundation methods used to fix the offshore reactive compensation substation to the seabed—

(a) where monopile foundations are used—

(i) the area occupied by the foundations and the scour protection must not exceed 1,963 square metres;

(ii) the diameter of each foundation must not exceed 10 metres;

(b) where jacket foundations (driven/drilled piles) are used—

(i) the area occupied by the foundations and the scour protection must not exceed 1,414 square metres;

(ii) the number of piles per jacket must not exceed 8;

(iii) the diameter of each pile must not exceed 3 metres;

(c) where jacket foundations (suction piles) are used—

(i) the area occupied by the foundations and the scour protection must not exceed 6,362 square metres;

(ii) the number of piles per jacket must not exceed 4;

(iii) the diameter of each pile must not exceed 15 metres;

(d) where gravity base foundations are used—

(i) the area occupied by the foundations and the scour protection for each individual structure must not exceed 6,362 square metres;

(ii) the seabed levelling diameter must not exceed 70 metres;

(iii) the cone diameter must not exceed 50 metres at its base.

(8) The combined total volume of scour protection for the wind turbine generators and the offshore accommodation platforms forming part of the authorised development must not exceed 4,761,555 cubic metres.