Tree Diagnostics & TPO Application in St Helens

Client: Private Home Owner

Project Type:

Sonic Tomography, Resistograph Drilling & QTRA Assessment for a Ganoderma‑Affected Beech Tree

Overview:
Urban Tree Management was instructed to undertake a detailed tree diagnostic and risk assessment on a mature European beech (Fagus sylvatica) protected by a Tree Preservation Order (TPO) in St Helens. The tree displayed multiple signs of structural decline, including Ganoderma fruiting bodies at the base, at an old pruning wound, and at the main union leaning over an access road.


Due to the tree’s protected status and the potential risk to road users, a quantitative, evidence‑based assessment was essential. We carried out:

  • Sonic tomography
  • Resistograph micro‑drilling
  • QTRA (Quantified Tree Risk Assessment)


This provided a clear, defensible understanding of the tree’s internal condition and associated risk level.

Key Structural Concerns Identified


Ganoderma at the Base
A large Ganoderma fruiting body was present at the base of the stem, immediately raising concerns about potential basal decay and reduced structural stiffness. The presence of this decay fungus at ground level also suggested possible compromise of the root‑plate, which is critical for overall stability. Even in isolation, this finding justified the need for advanced diagnostic investigation to determine the extent of internal dysfunction.


Ganoderma at an Old Pruning Wound

A second Ganoderma fruiting body was identified at a historic pruning wound higher up the stem. This indicated that decay was not confined to the base but was also tracking vertically through dysfunctional heartwood. The pattern was consistent with progressive white‑rot development, increasing the likelihood of internal decay columns extending through the main stem. This significantly elevated concern regarding the tree’s long‑term structural integrity.


Ganoderma at the Main Union Over an Access Road

The most critical finding was the presence of Ganoderma at the main union, located on the side of the tree that leans directly over an access road. Decay at such a key load‑bearing junction raised the possibility of shear failure at the union and a reduction in bending strength. Because the target beneath the canopy included both vehicles and pedestrians, the consequence of failure was considerably higher.


This made a QTRA assessment essential to quantify the actual level of risk and determine whether it remained tolerable.


Integrated Decay Detection and QTRA Analysis


The assessment began with a detailed Visual Tree Assessment to identify external signs of decay, evaluate crown vitality, assess root‑plate stability and document fungal activity, including the multiple Ganoderma fruiting bodies. This initial inspection guided the placement of diagnostic equipment and shaped the investigative approach. Sonic tomography was then used to produce a cross‑sectional image of the stem, revealing internal decay pockets, cavities and areas of reduced wood density, while resistograph micro‑drilling provided precise confirmation of residual wall thickness and the depth of decay in critical load‑bearing zones.


To complement the diagnostic findings, a full QTRA assessment was completed to quantify the probability of failure, likelihood of impact, target occupancy and consequence of failure. This produced a clear numerical risk rating that allowed the local authority to make a defensible, evidence‑based decision grounded in actual risk, structural condition and site usage.

Work With Us

If you’re dealing with a protected or high‑value tree and need clear, defensible evidence to support a planning or TPO application, Urban Tree Management can help. We specialise in advanced tree diagnostics, including sonic tomography, resistograph micro‑drilling, QTRA risk assessment and detailed decay investigation for complex or safety‑critical trees. Our approach is grounded in technical accuracy, transparent reporting and practical, risk‑based recommendations that local authorities trust.


We support homeowners, developers, estate managers and commercial clients across St Helens, Merseyside, Greater Manchester, Lancashire, Cheshire and the wider North West, providing fast, professional assessments and clear guidance on the most appropriate next steps. If you need expert input, a second opinion or a fully prepared TPO submission, we’re ready to assist.


Get in touch to discuss your tree, request a quotation or arrange a diagnostic inspection.