SLOUGH MULTIFUEL

Sustainable waste-to-energy facility revolutionises landfill alternatives

SERVICES
Civil Engineering

COMPLETION DATE
February 2021

CLIENT
Scottish and Southern Energy

WHERE
Slough, West London

SECTORS
Energy

Elysium Construction have completed Civil Enabling works to facilitate the development of a new 500MW energy-from-waste facility, known as Slough Multi-fuel, operated by SSE (Scottish and Southern Energy).

To prepare the site for the construction of the new facility, the first step required was to undertake soil improvement measures. By removing all existing building foundations from the site, we enabled micro-piles to be installed for the new facility.

It is estimated that approximately 5,000m³ of concrete was broken out of the ground alone, which was then crushed to finer particles and re-utilised as backfill material for the top layer of the now improved ground. Levelling of the site consisted of removing around 15,000m³ of the existing soil, which was then checked for contamination and disposed of accordingly.

Prior to any major works taking place, all live services had to be identified, and redundant services removed and diverted. The site was riddled with previously unidentified live electric cables, water, steam and gas pipes - all of which had to be identified and removed or diverted.

All services currently crossing the site had to be diverted around the perimeter of the future building blueprint and new ones installed. These included steam, gas, water and electricity. A 7m deep cofferdam was built to facilitate the identification and diversion of two cooling water pipes, and a 250m long and 4m deep Reinforced Concrete block, housing a total of more than 8km ducts and high voltage electric cables, was built to run across the perimeter of the site. The heat generated by the cables means that over time they can melt: to prevent this, they had to be encased in High Density Concrete, with specific heat capacity properties, reaching a total compressive strength of more than 80MPa.

The site included a water mains pipe, 500mm in diameter, which crossed the site to feed water to the Slough trading estate. As an essential part of the surrounding infrastructure, it was vital to divert it without causing major disruptions to nearby residents, shops and power plants. A new water main around the site was installed and pressure-tested, ready for the diversion to happen over a 48 hour period at the weekend, to minimise disruption. On the day of the diversion, Elysium Construction built and poured an RC thrust block within 3 hours, using additives to the concrete mixture to ensure the block achieved the desired compression strength of 10MPa after just 16 hours, so that the water feed could be turned back on as quickly as possible.

This was a complex civil engineering project - but one which has been completed on time and on budget, thanks to the technical expertise of Elysium Construction and efficient project management.