Old Walsall Road, Hamstead, Birmingham

The development comprises three industrial units on a site underlain by a wedge of weak alluvial deposits. Menard was approached in the first instance by the client’s consulting engineer, who was looking for advice on potential ground improvement solutions for this site. Subsequently, after a process of competitive tendering, we were awarded the contract by the main contractor.

A wedge of weak alluvial deposits including horizons of peat is present beneath made ground at the southern end of the site, but these weak soil deposits thin out across the site such that gravelly sand (River Terrace Deposit) directly underlies the made ground of the northern end at shallow depth. At the request of Menard, additional site investigation in the form of Cone Penetration Tests (CPT) was undertaken to fully map out the extent of the weak soils.

The findings of the CPT was also of benefit to the main contractor’s consulting engineer, as it meant that they could delineate the required extent of the CMCs, such that the ends of two of the industrial units were founded directly onto the River Terrace Deposits (with movement joints incorporated as appropriate). Within the area of weak alluvial deposits, CMCs were installed to depths of between c.2.5 m to 6.5 m, varying in line with the thickness of the weak soils. Nearly 1,000 CMCs were installed to a total building footprint area of c.3,300 m2, to enhance the allowable bearing capacity of the foundations to 150 and 200 kPa and to support floor slab UDLs of 38 and 50 kPa. The CMCs have been designed to reduce the residual settlement to 25 mm with relative differential settlement of less than 1:500.