Ground improvement specialist Vibro Menard has started work on the Avonmouth Wind Power Project at Bristol Sewerage Treatment Works using an innovative new technique for the first time in the UK.
The work, for main contractor Lagan Construction, is being carried out using the bio-modulus column method that combines controlled modulus columns (CMC) with stone column to cope with the 150KPa foundation load and slab loads of 50KPa called for by the four wind turbines.
According to Menard, the CMCs will transfer the load from the weak ground to stronger underlying strata but has been combined with stone columns to reduce the risk of punch failure in the load transfer platform. The original design for the project combined CMCs with vertical drains but concerns over the creation of a contamination pathway led to the redesign.
In total Menard will install 2719 columns at Avonmouth. The 320mm diameter columns will be installed to depths of between 9 and 17m.