SHORING FIRM Groundforce has supplied systems to support two unusually shaped excavations for a remediation project in the centre of Manchester.
During the Industrial Revolution two circular brick tar pits were built on the Grand Island site off Whitworth Street West to contain waste products from a gasworks.
When the site, now home to British Telecom, was redeveloped, the gasworks was demolished and the pits buried under 3m to 4m of fill.
The site is undergoing a £0.5M redevelopment and the 18m and 29m diameter pits are being re-excavated, cleaned up and backfilled with inert material.
Groundforce supplied contractor DCT Civil Engineering with its fully articulating Mega and Maxi brace systems for the 18m and 29m diameter, 3m and 3.6m deep octagonal excavations. These support the fill above the buried pits and allow remediation below.
Octagonal excavations were chosen to eliminate the need for internal strutting - which would have restricted working space - and to minimise the amount of spoil removal.