In November 2022 Geobear stabilised a property in Bristol adjacent to a 22m Oak tree. The property was featured in the local media as the tree had been identified as the cause of subsidence to the building and was due to be removed. Campaigners looked to prevent its removal by camping in the tree itself.
Before the tree was felled, the loss adjuster managing the subsidence insurance claim became aware of the new Geobear process and we designed a solution to stabilise the property without the need to remove the tree. Geobear delivered the solution in November 2022 and it was featured on BBC news.
The usual alternative in this situation would have been to remove the tree and monitor the property for further movement. After 18-24 months of monitoring a decision would then be made as to whether the structural stabilisation work would need to be conducted.
The alternative to a geopolymer solution is traditional underpinning. The traditional approach takes months to complete as a full excavation of the area around the foundations is required and concrete is poured beneath the foundation. In this case, it would lead to a lot of disruption and as the gable wall foundations are on a side street would have required a road closure.
Geobear was selected in this instance for two reasons. Firstly because the solution means the tree credited with causing the subsidence would not need to be removed and secondly because the method of geopolymer injection could be implemented in a matter of days with minimal disruption to the home-owner / occupants. Furthermore, the road would not need to be closed.
For all Geobear projects site investigation data is analysed and a solution is designed that features lateral and vertical soil interventions. A matrix of soil interventions would be laterally along the affected foundations and spaced at intervals vertically beneath the foundations. The quantity and depth of interventions are governed by the degree of soil desiccation and the presence of tree roots.
Geobear geopolymer material is injected into the soil and migrates through fissures and compacts the areas. Existing tree rootlets are crystallised and are no longer able to withdraw moisture.
This project was delivered within three days.
The solution was featured on the BBC news website: https://www.bbc.co.uk/news/uk-england-bristol-63731821
Bristol Mayor, Martin Rees commented:
“This is a really good piece of news, we’ve found a way to protect the home without felling the tree. Tree’s make up the lungs of Bristol, they support our city’s ecology. We need to protect our biodiversity, we have to deliver in a sustainable, decarbonised way.