Soil stabilisation and ground remediation specialist Deep Soil Mixing has used its soil mixing solutions for foundations on a high-quality housing project in St Mary's Bay, Kent, England.
The company's soil stabilisation techniques are being used across the whole site under residential dwellings to prevent extreme settlements from variable ground. Soil mixing has been used on this project to save valuable time, estimated to be up to a year off the programme compared with conventional solutions as well as providing improved ground stability behind coastal defences for the client, Compass Builders.
The site is close to a beautiful sandy beach with stunning views out across the English Channel with planning permission granted by Shepway District Council for the development, which will be called ‘The Sands' on a brownfield site of a former hotel and military base that has been demolished. The scheme will consist of a range of three, four and five-bedroom houses and one and two-bedroom apartments and will also include a new landscaped coastal park area, car park and children's play area.
Deep Soil Mixing has undertaken both column and mass mixing using its double rotary mixing head designed by the company's director Robert McGall, installing soil mixed columns to a depth of up to 10m as well as a soil mixed mattress across the whole of the site covering an area of just under 11,000m2.
The company has also used a cutter soil mixer on this project to install 200 soil mixed panels. The cutter soil mixer was specifically used on the St Mary's Bay project to overcome some isolated areas of very stiff layers of clay, which had softer soils below making it necessary to mix through the clay into the soils below to enable remediation to take place.
In response to a foundation enquiry from the consulting engineers Considine, Deep Soil Mixing put forward various options that soil mixing could provide to deliver a design solution that saved the client time and reduced cost compared to alternative ground engineering solutions.
Roland Cooper Chartered Civil Engineer and director of Considine said: "These works are shaving more than a year off the programme for a conventional ‘load and settle' solution as well as providing improved stability behind coastal defences. We do like an innovative solution here at Considine."
Deep Soil Mixing always advises getting involved with clients and their designers as early as possible in the development process to create engineered solutions that offer real cost savings for projects including benefits such as reduced vehicle movements and the efficient use of on-site materials on projects, reducing the carbon footprint and offering environmentally friendly sustainable solutions.
Soil mixing was specified for use on this residential site to eliminate differential settlement across the site. The alternative solution was to either pile the buildings which would have created huge conflicts in differential settlement or to remove soil from the site and take to landfill, which again was not a cost-effective or environmentally friendly solution. Soil mixing is also quieter than piling and has zero vibration, which meant there was no impact on the surrounding residents.
Benefits of soil mixing over traditional ground remediation methods
- Reduces construction programme
- No need to excavate and cart away so reducing landfill tax charges
- Zero vibration during construction
- Minimal spoil removal
- Wide range of soils can be treated compared to other solutions
- Soil can be used as construction material
- No need to bring costly and bulky materials on site
- Environmental - a reduction of carbon footprint
- Effective on different soils, including soft soils, floodplains, contaminated land, peat, silts and alluvium etc.
- Increased bearing pressure controls settlement and reduces permeability
