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Installation of an In-Situ Soil Mix Barrier

St Anthony’s Tar Works operated between 1920 and 1981 during which thousands of litres of tar were lost to ground.  Since its closure several investigations have been undertaken to better understand the extent of the contamination and also the ground conditions, there have also been two previous failed remedial schemes attempted at the site.

Sirius’ involvement in the site began in 2009 which consisted of further site investigation, risk assessment, remediation options appraisal, remediation strategy and obtaining approvals for remediation.  After funding was granted by Growth Deals to the North East Local Enterprise Partnership Sirius successfully tendered to carry out the agreed scope of remedial works and following completion of feasibility testing mobilised to site in February 2016.

Client Name: Newcastle City Council




Project Description

The agreed Remediation Strategy to prevent the coal tar contamination migrating into the River Tyne consisted of the installation of a low permeability soil mix cut-off barrier (approx. 360 metres long and an average of 13 metres deep) followed by installation of an associated drainage system to intercept and control groundwater and surface water flowing behind the cut-off barrier, repairs to the existing quay wall and revetment, localised soil slope re-profiling (with cover system) and reinstatement of the riverside footpath.

Innovation & Value Engineering

Sirius had the specialists in house to carry out slope and global stability calculations, in addition the drainage system required redesigning in order counteract barrier realignments caused as a consequence of unforeseen below ground obstructions.  The barrier works were completed within the estimated time-frame without injury to personnel and without causing damage to the quay walls/revetments nor any environmental damage mainly through detailed planning and professional implementation of each phase of works.  The barrier works were comprehensively validated through retrieval of cores from the barrier itself and medium/long term groundwater monitoring, the works were independently supervised by an environmental consultancy on behalf of the Client Newcastle City Council. All parties are extremely happy with the works completed to date.

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