Internal Tree Decay Testing for Local Authority
THE CHALLENGE:
A local authority in the North West had identified a significant mature tree in a public open space that had been showing signs of progressive decline over several years — including reduced crown vigour, areas of deadwood, and visible fungal fruiting bodies at the base of the stem.
The tree was located in a high-footfall area with regular public access, and the authority's tree officers required objective, measurable evidence of the tree's internal structural condition before a management decision could be made — particularly given the tree's significant amenity value and the reputational and legal implications of an incorrect assessment in a public space.
OUR ROLE:
Urban Tree Management was commissioned to carry out a specialist internal decay investigation using the Arbotom sonic tomography system and IML Resistograph resistance drilling.
The sonic tomography investigation mapped the internal condition of the stem at multiple assessment heights, producing two-dimensional cross-sectional tomographic images that clearly showed the location, extent, and pattern of internal decay within the stem at each assessment point. Resistograph drilling at the sensor locations provided direct physical confirmation of the tomographic findings, measuring the residual wall thickness and confirming the presence and depth of the decay.
The combined data from both instruments was analysed in the context of the tree's overall condition — including its crown size and wind loading, the root environment, and the species-specific decay resistance characteristics — to produce a structural assessment and risk evaluation that directly informed the management recommendation.
All findings were documented in a full written report in a format suitable for submission to the local authority's legal and insurance teams.
THE OUTCOME:
The investigation provided the local authority with the objective, independently reproducible evidence of the tree's internal structural condition that they needed to make a proportionate, defensible management decision in a high-profile public space.
The data confirmed that the extent of internal decay was sufficient to represent an unacceptable structural risk in the target-rich environment, and the authority was able to act on the management recommendation with confidence — supported by a comprehensive written report that documented the methodology, findings, and decision-making process clearly and transparently for their governance and insurance records
Work With Us
Urban Tree Management supports Local Authorities across the North West with advanced diagnostic investigations and defensible risk assessments for complex, high‑profile or safety‑critical trees. We understand the pressures placed on council tree officers: balancing public safety, statutory duties, budget constraints and increasing scrutiny over decision‑making. Our specialist services — including sonic tomography, resistograph micro‑drilling and QTRA risk analysis — provide clear, quantifiable evidence that strengthens case files, supports enforcement, and ensures decisions stand up to internal review, public challenge or appeal.
We work closely with planning teams, tree officers, highways departments, estates, parks and legal services, delivering transparent reporting, rapid turnaround times and clear recommendations grounded in best practice. Whether you require an independent diagnostic investigation, support with a contentious TPO case, verification of decay in a high‑risk location, or expert input for a public enquiry, we provide a reliable, professional service that integrates seamlessly with your existing processes.
Get in touch to discuss a case, request a quotation or arrange a diagnostic inspection.