Kidderminster, Silverwoods Trade Park

Menard was approached to provide a quote for ground improvement to support four small industrial units. This development is adjacent to a site where we had installed Controlled Modulus Columns (CMCs) during 2021. Both developments are underlain by variable depths of waste lime fill associated with a former sugar beet factory. For the neighbouring scheme, a piled solution had originally been proposed, but Menard had suggested a CMC alternative solution and this was subsequently adopted by the client in agreement with the Consulting Engineer. For this scheme, the same Consulting Engineer proposed CMCs to support the units located predominantly within the waste lime fill, and vibro stone columns (VSC) to support the two units located outside the areas of waste lime fill.

The site investigation comprised dynamic sampling boreholes and trial pits, supplemented by cone penetration tests. The waste lime fill comprises very soft to soft silt and clay up to a depth of c.7m, which is underlain by medium dense sand onto weathered sandstone. Outside the waste lime area a thin wedge of made ground consisting predominantly of sand is present over medium dense/dense sand onto weathered sandstone.

Both solutions were tailored to reflect the variable depth of poor ground. CMCs were installed to depths below working platform level (WPL) ranging from 2.8m to 9.4 m beneath Units 1 and 2, whilst VSCs were installed to depths below WPL of 0.9 m to 4.0 m beneath Units 3 and 4. The ground improvement will support pad and strip foundations with a required SLS bearing capacity of 125 kPa and floor slabs of UDL 50kPa, and will control the total settlement to <25 mm, and relative differential settlement to <1:500. Plate load testing was undertaken to verify the ground improvement works, and the whole works were completed within a 3 week period using 1 CMC rig and 1 VSC rig.