As part of the Chesterfield to High Marnham project we propose to build and operate two new substations - one 400 kV substation  (“the scheme”) near Chesterfield (“the site”) and another 400 kV substation (“the scheme”) in High Marnham near Normanton on Trent in Nottinghamshire (“the site”). The substations would enable us to uprate the existing Chesterfield to High Marnham overhead lines in the region and connect future electricity transmission network projects as part of The Great Grid Upgrade.  

The delivery of this Project would ensure that we continue to deliver electricity safely, reliably and efficiently to the customers and communities we serve - all while working towards building a cleaner, fairer and more affordable energy system for the future. 

High Marnham

The site is approximately 36 hectares (ha) located on land that intersects with the existing 400 kV and 275 kV substations and adjoins the former High Marnham Power Station site, which has been decommissioned and removed. 

The new substation would be within a compound approximately 690m x 200m and includes two supergrid transformers, which are used to increase or decrease the voltage of electricity between different circuits, protection and control equipment, substation plant and new substation control infrastructure, 16 bays, ten overhead line gantries which are bridge-like structures with platforms used to support equipment and cabling, and 20 permanent buildings. 

The highest structures within the substation compound would be the overhead line gantries at approximately 12.5m high. 

There would be extensive landscaping for this proposal that has been designed to provide environmental mitigation and satisfy the required 10% Biodiversity Net Gain (BNG). The landscaping design comprises: 

• 31m of species rich hedgerow with tree planting along the western boundary to reduce visibility from residential properties on the western side of the site boundary;  
• hedgerow to provide visual screening to residential properties along Hollowgate Lane and on Sparrow Lane Park. Native hedgerows to the south of the substation; 
• existing hedgerow re-installed with native hedgerows after completion of drainage works; 
• woodland planting with native species to supplement screening along the southern boundary and to ensure integration with the existing Local Character Area; and 
• grassland planted within the northern and southern areas of the site. 

We also propose overhead line connections to the new 400 kV substation at High Marnham to the wider network. This would include the installation of short stretches of overhead line between the new 400 kV substation and the existing overhead line, as well as the removal of some existing stretches of overhead line, together with the temporary works (such as temporary masts) required to make these permanent changes.