Approved Plans & Report - 51987.3004.01

Brief:
  •   Identify trees impacted by the proposed construction of replacement retaining walls.
  •   Determine Tree Protection Zones of these trees using the Australian standards 4970-
      2009, Protection of trees on development sites
  •   Recommend any treatments or ongoing monitoring or maintenance.

Methods and Procedures:
  •   Discussions on site with Josh De Wit to determine the extent of works and
      methodology.
  •   Visual inspection of the standing stock at ground level and light probe investigation of
      the root plate of the trees to determine the extent and health of sub-canopy structures.
  •   No scientific analysis was conducted during the preparation of this report.
  •   Australian standards 4970-2009, Protection of trees on development sites, AS 4373-
      2007 pruning of amenity trees and AS2870-2011 have been referenced to prepare this
      report.
  •   International Society of Arboriculture Tree Risk Assessment Manual was used to
      provide recommendations in this report
  •   The weather on the day of the inspection was fine, low wind and a warm temperature

Summary
  •   This site located at Noosa Heads is a residential dwelling. This dwelling has been
      constructed on a steep embankment in an area classed as high slip risk.
  •   As this site is classed as a high slip risk area it is essential to maintain the integrity of
      the existing retain walls to manage water runoff and for erosion control.
  •   During the inspection it was determined that all existing sleeper style retaining walls
      have failed from the effects of tree trunk expansion, root ingress and rotting of the
      sleeper wall material. These walls need to be replaced to ensure the stability of the
      site, protect the foundations of the existing dwelling, mitigate the effects of water
      runoff and for erosion control.
  •   The influence of roots from the mature trees on site will be causing soil moisture
      suction (migration of moisture towards the trees.) this abnormal moisture condition at
      the foundations of the dwelling and retaining walls cause shrinkage and subsidence.
  •   The Australian Standard AS2870-2011 recommends large growing trees and tree
      groups should be grown at least one and a half times their mature height from
      foundations. All trees listed have portions of the existing dwelling within their
      Structural Root Zones.
  •   Trees appear to be in poor to average condition with some demonstrating issues
      arising from poor prior pruning practices. This prior pruning does not meet the
      Australian Standards and has created epicormic regrowth and branch defects which
      have rendered these trees as unstable.
  •   All proposed works to reconstruct the retaining walls, falls well within the Structural
      Root Zones and Tree Protection Zones of the trees per the Australian standards 4970-
      2009, Protection of trees on development sites.
  •   It is impossible to gain access or clearance zones away from the trees to carry out the
      essential reconstruction works which will render the trees as not viable.
  •   The only way to sufficiently mitigate these effects to protect the foundations of the
      existing dwelling and new retaining walls is to remove these trees.
  •   I recommend the removal of these trees.