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Tree risk assessment case study

Challice Consulting Ltd were instructed to carry out a tree survey on one Veteran Oak tree (reference number 13) for health and safety and to make recommendations for appropriate tree works to reduce the risk of tree related harm or damage to an acceptable level.

The purpose of this report is to ensure that the owners of the site have taken reasonable steps to prevent injury to staff/visitors or damage to property by the subject tree. The Owners and Occupiers Liability Acts 1957 and 1984 state that the person responsible for trees has a ‘Duty of Care’ to carry out regular tree inspections so that sufficient care is taken to avoid foreseeable harm or damage by the trees under the individual’s control.

Tree owners and managers have a duty of care and as such have a direct responsibility to ensure that trees do not pose a danger to the public, staff or property. To ensure the correct procedures are in place this report has been produced using current guidance which is are underpinned by the five key principles set out below by the National Tree Safety Group (NTSG):

  1. Trees provide a wide variety of benefits to society

  2. Trees are living organisms that naturally lose branches or fail

  3. The overall risk to human safety is extremely low

  4. Tree owners have a legal duty of care

  5. Tree owners should take a balanced and proportionate approach to tree safety management

Tree Survey Method

The subject Veteran Oak tree was surveyed from ground level and a climbing inspection was undertaken to a height of 14m on 7th September 2022. A full description of the tree is provided in the Tree Survey Schedule at Appendix 1. A nylon hammer was used when decay was suspected, combined with a 400mm metal probe to aid diagnosis. A Picus Tomograph was carried out by Mr. Kim Gifford out at four different heights on 7th September 2022 to establish the decay patterns in the stem. (see Picus Tomograph test report at Appendix 2). Any fungal brackets/fruiting bodies have been identified and assessed with regard to the safety implications.


The height and crown spread of the subject tree was estimated as the accuracy of these measurements is generally not critical to the decision making process when recommending necessary tree works.


The Tree Survey Schedule documents the tree dimensions, defects and assesses the risks and recommends remedial tree works, tree work priorities and re-inspection schedules based on the list below:

  • Identified tree hazards

  • Likelihood of failure

  • Targets within striking distance of trees

  • Proximity of trees to property including but not limited to buildings, fences, footpaths, roads, and access drives

  • Consequence of failure

  • Nature conservation and historic value of the tree/s


There are a number of ways that trees can be protected by law within the UK and include:

Legal Status

The protection status of the subject Veteran Oak tree has not been ascertained. It would be prudent to check the protection status permission before any tree works are carried out.

Type of Tree Protection


Legal Authority

Tree Preservation Orders

Local Planning Authority


Local Planning Authority

Conservation Areas


Felling Licence system


Restrictive Covenants

Forestry Commission

A legal agreement made by a Solicitor

It is important to obtain written permission where trees are protected from the specified legal authority before any tree work is undertaken to avoid prosecution.


General Site Description

The subject site is situated within the administrative jurisdiction of Elmbrigde Borough Council and consists of the gardens of the subject site.


The subject tree is located adjacent to a footpath in a part of the garden where people congregate making this a medium to high target area.

Tree Appraisal

The protection status of the subject Veteran Oak tree has not been ascertained. It would be prudent to check the protection status permission before any tree works are carried out.

Please refer to the Tree Survey Schedule with Recommended Tree Works at Appendix 1 for specific tree details.

Location of Decay Fungi Laetiporus sulphureus (Chicken of the Woods)

Location of the Deep Cavity at 6m


Any recommended tree works should be carried out in their entirety in accordance with the time frames given in the Recommended Tree Work Schedule at Appendix 1.


All works are to conform to British Standard 3998:2010 ‘Recommendations for Tree Work’ and to current arboricultural best practice. Tree works are to be undertaken by a professional Arboricultural Contractor who has the appropriate knowledge, experience and insurance cover. Commencement of all or some of the proposed works may require written authorisation from the Local Planning Authority.


The Wildlife and Countryside Act 1981 (as amended by the Countryside and Rights of Way Act 2000) and the Habitat Regulations 1994 place a legal obligation on tree owners and Arboricultural Contractors working on trees to protect wildlife species and their habitats. Care should be taken to avoid disturbing all wild birds, Bats and Badgers (including nests, roosting sites and setts). This normally dictates that pruning and felling should not be carried out during bird nesting season (1st March until 31st July) unless safety is an issue.


The tree inspection was carried out on 7th September 2022 and extensive decay was identified using numerous methods as described above. Due to the historic importance of this Veteran Oak and the clients will to retain this tree, a crown reduction of approximately 8m is recommended.


The application of woodchip under the canopy of the subject tree will reduce the compaction to the soil and add organic matter to the soil which will improve the tree’s vitality and soil water retention.


No soil samples or wood tissues have been sent for laboratory analysis unless specifically stated. My assessments are based on professional experience and expert observation at the time of the inspection. No liability can be assumed to rest with Challice Consulting Ltd. should site conditions or features alter after my inspection. This report has been prepared for the sole use and benefit of the Client. Any liability of Challice Consulting Ltd. shall not be extended to any third party.

No part of this report is to be reproduced without authorisation from Challice Consulting Ltd.

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