The potential that soil stabilisation offers for residential developments on difficult sites is demonstrated by its use by Seddon at the Gifford Lea retirement village in Tattenhall, Cheshire.
The Tattenhall project is one of two firsts: the first documented use of lime to improve soils for a residential development and the first such project to receive a comprehensive industry warranty developed by Premier Guarantee
Although the use of soil stabilisation is widely adopted for commercial and industrial projects, its use for residential developments has been obstructed by the unavailability of a specific housing industry warranty.
The first two phases of the Gifford Lea retirement village were constructed on vibro-stone column foundations. However, difficult ground conditions for the construction of phase three – eight blocks of three-storey timber-framed buildings – called for a different approach to achieve the required subgrade levels for the access roads and parking areas and to provide a platform for the piled foundations.
The natural ground was predominately stiff clay with areas of gravelly sand and significant groundwater inflows. Site investigations found that the stockpiled soils from phases one and two were unsuitable and too wet for re-use as general fill for phase three. Removing the stockpiled soils and bringing in better fill materials would have been slow and costly. Instead Seddon Construction worked with consulting engineer WSP and specialist contractor Combined Soil Stabilisation to develop an alternative on-site lime modified solution.
Combined Soil Stabilisation managing director Stefan Stansfield explained: “Such an approach is widely used for commercial and industrial projects where loading and flatness requirements far exceed those required by residential developments. However, despite this, soil stabilisation solutions are not the norm for the residential sector. Ours and WSP’s experience of soil stabilisation convinced us that this was right approach for the Tattenhall project.”
Mr Stansfield continued: “Following our proposal, Seddon Construction approached Premier Guarantee who proved to have the vision and understanding of the positive groundwork solutions that soil stabilisation can provide for residential developments by agreeing to provide a project warranty. We believe the Tattenhall project to be the first residential project in England to be so underwritten by an industry warranty and hope that this will forward the use of soil stabilisation for other such projects.”
Seddon is scheduled to complete phase three of Gifford Lea retirement village this spring.
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