Air spades – A way to assess roots for planning applications.
Background
TTC had the opportunity to collaborate with Arboraeration, a specialist in tree root investigations, at one of our residential sites in Godalming, Surrey. The project involved assessing the presence of significant tree roots at a location where the client was planning to build an extension next to an oak tree. Due to the proximity of the tree, it was essential to determine if the roots extended into the proposed building area, as this would influence the foundation design and cost implications of the project.
Key Outcomes
- Confirmed No Major Roots: Air-spading verified the absence of significant tree roots in the construction zone.
- Reduced Foundation Costs: The client was able to use the less expensive traditional foundation method.
- Secured Planning Approval: Non-destructive evidence provided a pragmatic and approved basis for the build.
Challenge
All trees have extensive root systems that can spread far beyond the canopy, and the theoretical RPA calculated at a BS5837 survey. Construction work near such trees must be considered to avoid damaging roots, which could compromise the tree’s health and even its stability. Accurately identifying what roots are present will help make an informed decision on how to proceed with the project.
Solution
To assess the root structure without harming the tree, we employed a non-invasive method known as air-spading, undertaken by Arboraeration. This technique uses compressed air to remove soil around the roots, allowing us to inspect and record them without causing significant damage. Unlike traditional excavation with a spade, which can easily cut roots, the air-spade preserves the integrity of the root system. This method allowed us to visually identify the location and size of the roots within the area of interest.
Results
The air-spade investigation in this instance did not reveal the presence of any significant roots. This was recorded with photographic evidence and supplied to the Local Planning authority within the accompanying report. This resulted in the client being able to use the lower cost traditional foundation method.
Conclusion
Air-spading proved to be an invaluable tool for this project, offering an effective, non-destructive solution for assessing tree root locations within an area of a proposed foundation. It enabled us to balance the needs of both the tree and the client, ensuring a successful, pragmatic and cost-effective outcome.
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