Mitigating the visual impact of electricity lines
National Grid’s Visual Impact Provision project is a £500-million scheme that aims to mitigate the visual impact of existing electricity lines throughout the UK. In Dorset, the project involves replacing a section of overhead line near the villages of Winterborne St Martin (Martinstown) and Winterbourne Abbas with underground cabling.
The project includes:
• replacing about 8 km of existing 400-kV overhead line with underground cabling, including removing 22 pylons
• constructing two new sealing end compounds to connect the new underground cables to the remaining overhead line, one to the north of the A35 and Winterbourne Abbas, and the other to the south of Friar
Morgan Sindall Infrastructure, the principal contractor, is delivering the £80-million project as part of its four-year engineering, procurement and construction framework with National Grid. Working closely with Morgan Sindall, RSK’s habitat management team undertook the second stage of environmental mitigation work in Dorset and the subsequent installation of stock-proof fencing and associated gates.
Undergrounding the 400-kV overhead lines required hedgerow clearance to be undertaken in two stages because of the presence of dormice. On completion of the work, all the hedgerows will be replanted and reinstated.
As part of this work, the RSK habitat management team grubbed up 789 m of hedgerow stumps and then forestry mulched and processed them. The ground-up arisings were left in situ. The team also reinstated the excavated areas back to the existing ground levels and ensured smooth-flowing contours. The team also supplied and installed 10 metal field gates and repaired and reinstated 296 m of existing stockproof fencing to ensure that landowners’ fields remained stock-proof and to prevent livestock from entering the working easement.