CASE STUDY
Date: January 2022
Client: JBA Bentley
Project: York Flood Alleviation – Clementhorpe
Environmentally friendly ground improvement solution soil mixing, was used on the essential flood relief work in York recently when Deep Soil Mixing Ltd was contracted by JBA Bentley to assist with their Flood Relief Scheme at Clementhorpe in York for client the Environment Agency.
Employed to work on the Environment Agency’s flood relief scheme on the River Ouse, York, Deep Soil Mixing Ltd constructed a 240metre long soil mixed flood defence wall to protect the 135 homes at risk of flooding in the Clementhorpe area.
Background
The city of York has always been prone to flooding and after more than 620 homes and many businesses were flooded in York in 2015, the government allocated an additional £45million to the Environment
Agency to better protect the 2,000 homes in the city.
The work recently completed by Deep Soil Mixing Ltd was part of the wider flood relief scheme and focussed on the Clementhorpe area of York. The project included a cut-off wall constructed with secant columns 5-6metres below ground, adjacent to residential homes.
This phase of the project was known as seepage mitigation as it created a semi-permeable barrier underground to stop the flood waters from seeping through the ground and passing underneath the above ground flood defences – and preventing low-lying areas beyond the flood defences from flooding.
The Soil Mixing Solution
The soil mixing solution involved mixing a binder into the existing ground using Deep Soil Mixing Ltd’s double rotary mixing head mounted onto an ABI TM14/17V rig to create an underground flood defence along Terry Avenue in Clementhorpe, approximately 240 metres long and up to 6 metres deep.
Deep Soil Mixing Ltd’s purpose-built double rotary mixing head has twin paddles that move in opposite directions to better distribute the materials as the soil is mixed. This improves the soil mixing process
and enables the mix designs to be more finely tuned and accurate, increasing both efficiency and costs benefits for the client, more so than using a single auger mixing head.
This bespoke equipment ensured Deep Soil Mixing Ltd was able to achieve the greatest soil distribution for the most effective underground flood defence barrier – and all with minimal disruption to the homes situated on the site.
The project started in August 2021 and was successfully completed in early 2022.
Rob Culledge, contracts manager at JBA Bentley, said, “Deep Soil Mixing collaboratively consulted during the design phase – and carried out numerous site visits in advance of the works – to plan in details of the temporary works, programme of installation and health and safety requirements
The good planning and consultation resulted in the final scheme being delivered ahead of programme and to budget.”
“We received great service and found Deep Soil Mixing easy to deal with and accommodating to change, paid good attention to health and safety and really impressed with their involvement to go above and beyond requirements.”
What are the benefits of using soil mixing?
Environmentally Friendly & Economical: Natural resources are spared as existing soil is used as aggregates. Many forms of contaminated ground can also be mixed which reduces transportation of raw materials to landfill. The use of soil mixing can also reduce construction programme and reduces carbon footprint with less vehicular movements.
Flexible: Effective on different soils, including soft soils, flood plains, contaminated land, peat, silts and alluvium etc. Flexibility also in design and application as well as installation of the soil mix not being affected by the weather. The final cured product can also be shaped, benched or battered to suit.
Reduces Construction Programme
Reduced Vibration: Soil Mixing induces very low vibrations, which reduces the potential impact to nearby utilities.
Increases bearing pressure, controls settlement and reduces permeability.
