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Norman Waterhouse

Recent Significant Tree removal appeals

In two recent judgements the Environment, Resources and Development Court (Court) has delved deeply into the provisions of the Regulated and Significant Tree Overlay of the P&D Code and the assessment criteria in respect of risk, and the reasonableness and effectiveness of mitigation measures.

The two judgements, Ditara Pty Ltd v The Corporation of The City of Norwood Payneham & St Peters Assessment Manager [2022] SAERDC 19 and Jarvis Property No. 3 Pty Ltd v City of Holdfast Bay Assessment Panel [2023] SAERDC 2 are factually quite similar, yet resulted in very different outcomes when the Court turned its mind to remedial measures.


In both cases, the Appellant sought to appeal the relevant authority’s decision to refuse the removal of a significant tree.

Both trees were River Red Gums located within and overhanging commercial carparks, one at the Britanna Hotel in Norwood and the other at a commercial building and proposed Jarvis Toyota dealership in Somerton Park. Both trees had a history of limb failure.

Dr Dean Nicolle, an esteemed botanist in the field of eucalyptus, gave evidence for the Appellants in both matters supporting the removal. The Respondents both engaged arborists to give evidence in support of retaining the trees.

In both judgements, the Court in interpreting the P&D Code applied a three-step process to assess the justification for removal:

  1. Is the significant tree worthy of retention? [which in both cases was uncontested]
  2. Is the tree damaging activity warranted?
  3. Have all reasonable remedial treatments and measures been determined to be ineffective?

Is the tree damaging activity warranted?

In both cases, the sole argument was whether the proposal represented an unacceptable risk with reference to PO 1.3 (a)(ii):

“(a) tree damaging activity is only undertaken to:

  • mitigate an unacceptable risk to public or private safety due to limb drop of the like”

The experts in both cases came to differing conclusions as to the risk posed by the trees. Dr Nicolle undertook a qualitative assessment of the risk posed by the trees, giving consideration to the context of the species and the consequent impact to persons due to the carpark setting. Overall, he assessed both trees as having a moderate to high risk to public safety such that removal was justified.

In contrast, the Respondents arborists employed the industry recognised TRAQ model, to assess tree risk. Using this model, both arborists determined the risk of the trees to be low, but conceded that the TRAQ model is sensitive to different inputs and the assessment may change if various assumptions made by the arborists were different.

Ultimately, the Court in both matters, preferred the evidence of Dr Nicolle due to his extensive study and biological knowledge of River Red Gums coupled with a continuation of the historical reservation with the sensitivity of the TRAQ style risk assessment model.

The Court held that both trees posed a moderate risk to safety, noting the setting of both trees in carparks serving commercial trade and the high level of human activity beneath the canopy elevates the risk when compared to similar trees located in different circumstances. Interestingly, the Court considered a moderate risk enough to justify removal, presumably thereby forming the view that a moderate risk was enough to be “unacceptable” for the purposes of PO 1.3 (a)(ii).

Have all reasonable remedial treatments and measures been determined to be ineffective?

Finally, the Court considered whether or not all other reasonable remedial treatments and measures had been determined to be ineffective. This is where the cases diverged.

In Jarvis, pruning, cabling and an exclusion zone were identified as the key alternatives to removal. While the practical knowledge of the arborist for the Respondent was accepted by the Court, again the detailed and scientific evidence of Dr Nicolle was preferred who advised the Court that pruning and cabling would be ineffective. Both experts agreed that an exclusion zone would mitigate the risk, but would result in an unreasonable material loss of on-site car parking.

The Court held that there were no reasonable effective remedial treatments available and the appeal was upheld, allowing the Somerton Park tree to be removed.

In contrast, the Court found in Ditara that tree pruning was a reasonable remedial treatment and the Appellant had not demonstrated that it would be ineffective. The Court was particularly assisted by the Respondent’s arborist who had practical experience in similar situations and prepared a thoughtful pruning plan which met relevant standards, retained the overall height and canopy form of the tree and managed risk.

As such, the Court held that while the Kensington tree did pose an unacceptable risk to public and private safety, the tree did not warrant removal while effective pruning was an available mitigation measure.

Take Home Message

These cases highlight the difficulties in assessing risk in the context of tree removal and that caution should be exercised in relying solely on an arborist’s assessment of risk. Further, it highlights that just because a tree represents an unacceptable risk it does not mean it warrants refusal, but that a careful consideration of remedial treatments and measures is required.

For more specific information on any of the material contained in this article please contact Aden Miegel on +61 8 8217 1342 or or Alice Tonkin on +61 8 8217 1372 or


2 March 2023



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