Supporting tank installation in difficult ground conditions

Horsey, Somerset

Project Overview

Location	Horsey, Somerset
Sector	Power & Energy
Products	Groundworks

A tank installation at the Sydenham Farm development in Horsey, near Somerset was quite the challenge with bad ground providing an obstacle for developers.

We were contacted by subcontractor Highfield Tunnelling Ltd, acting on behalf of contractor John Sisk & Son Ltd, for our help on this six month-long project.

The challenge

Borehole tests on the ground showed it was made entirely of silt and sand, which along with a high water table would require extra attention and monitoring during the whole project.

Tight trench sheeting was essential on this project and our M12 Overlapping Trench Sheets were the perfect option to combat this problem. With the difficult ground conditions on this site, it was essential that the lapped sheets were installed accurately, ensuring a good bite on the lap to prevent the ingress of fines with any groundwater. With the groundwater level at -2600mm in the 3400mm deep excavation, base stability problems were still possible.

Challenging Ground Conditions

A tank installation at the Sydenham Farm development in Horsey, near Somerset, presented significant challenges due to poor ground conditions. Borehole tests revealed silt and sand throughout, combined with a high water table requiring close monitoring.

Specialist Trench Support

Appointed by Highfield Tunnelling Ltd on behalf of John Sisk & Son Ltd, we supplied M12 Overlapping Trench Sheets to provide tight, secure excavation support in the difficult ground.

Managing Water & Stability

Accurate installation of the lapped sheets was critical to prevent groundwater ingress. With water levels at -2600mm in a 3400mm deep excavation, careful planning was essential to maintain base stability.

Our solution

Ninety M12 Overlapping Trench Sheets were driven into the ground first, with Mabey Hire engineers identifying the push and dig method as the best option.

The trench sheets were pushed into the ground with the toe-in depth of 3.4m required to combat the ground conditions.

Learn more about Super Shaftbrace

Excavations with the 45 tonne plant then began, first digging to 1m below the surface, allowing the first Super Shaftbrace to be installed at 0.75m and pressurised.

Excavations then continued down to 2.75m below the ground where the second frame could be installed and pressurised at 2.5m.

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