Epping Forest Retail Park, Loughton | CFA Piling | Vibro | Keller UK

Epping Forest Retail Park, Loughton

The scheme comprised a large retail park. Retaining walls were required to provide retention to the service yard access road, where the original levels fell by some 6.5m at the rear of the site.

The site is underlain by a wedge of fill materials up to 7.5m thick towards the rear of the site. In turn this is underlain similarly with a wedge of alluvial deposits as the site lies within the Roding Valley,a tributary of the Thames. The alluvium increases in thickness along the back of the retail buildings. Our challenge therefore was to support the proposed development in these variable and difficult ground conditions.

Late in the design stage, additional site investigation allowed a switch from a pile support system to vibro replacement to support the proposed buildings as well as the reinforced earth retaining walls.

A combination of the Top Feed and Bottom Feed Vibro processes using Keller depth vibrators were deployed to suit the varying ground conditions across the site. This approach was used to support both the retaining walls, as well as the foundations and floor slabs of the retail buildings with treatment depths ranging from 3.1 to 7.7m. The reformed profile to rear of the site was achieved efficiently using both Phi Group’s Titan and Textomur earth reinforced retaining walls, retaining up to some 6.5m height. The treatment was designed to enhance the settlement and bearing capacity characteristics of the ground to give control of future settlement to less than 25mm and allowable bearing capacities in the range of 30 to 150kN/m2, all designed to Euro Code EC7.

Client: Polofind Ltd

Main contractor: McLaughlin and Harvey

Year of Execution: 2016/17

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