Topographic, geophysical, geotechnical and soil contamination survey of a converter station site and underground HVAC cable route for a new 1 400 MW electricity interconnector project at Kingsnorth, Isle of Grain in Kent. The survey comprises non-intrusive survey techniques, boreholes, trial pits, dynamic probes, slit trenches and concrete coring to determine the underlying geological profile, mechanical properties and other relevant parameters of the geologic materials present on the converter station site and cable route to inform the design, construction and installation of the project.

Topographic, geophysical, geotechnical and soil contamination survey of:

(a) 4.3 ha converter station site; and

(b) 1.4 km x 20-55m wide underground HVAC cable corridor with total survey area of 4.3 ha. The overall survey area is 8.6 ha.

The survey comprises:

• topographic survey;

• buried utilities investigation;

• geophysical survey;

• geotechnical survey, including location-specific UXO surveys prior to any excavations;

• in-situ and field testing;

• geotechnical sampling;

• soil contamination sampling;

• tank base concrete coring.

The non-intrusive surveys comprise GPS RTK and/or conventional land survey methods, drone aerial mapping techniques, seismic refraction (30 m target penetration), Ground Penetrating Radar (GPR), electrical resistivity measurements and thermal resistivity measurements.

The intrusive surveys comprise 10 boreholes (30 m depth), 14 trial pits (3 m depth), 14 dynamic probes (10 m/30 m depth), 6 slit trenches (2.5 m depth) and 24 concrete cores (3 m depth).

Disturbed and undisturbed samples will be collected from boreholes and trial pits for laboratory testing for a range of geotechnical parameters and soil contaminants.