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Elements and Performance Criteria
Performance Evidence
An individual demonstrating competency must satisfy all of the elements and performance criteria in this unit.
There must be evidence that the individual has analysed the edaphic interactions of trees and structures for a specific site and has prepared a minimum of two reports, which must include:a report on damage to structures by tree rootsa report on the stability of tree with a defective or damaged root plate.There must also be evidence that the individual has:investigated soil conditions that contribute to structure and tree stability, including:angle of repose of soil materialssoil plasticityimpact of soil moisture on soil cohesion and plasticity modes of soil liquefactioninvestigated and tested soils for properties affecting soil conditions, including:measured soil moisture content and field capacitydetermined soil textureassessed level of soil cohesiondetermined shear strength of the soilinvestigated load bearing capacity of soilcalculated mass of the soil platedetermined root morphology, division and distribution and amount of buttressing of treedetermined species characteristics for development of tap root systemdetermined anatomical features of tree roots and identified tree roots for a given treeconducted research tests to determine forces and pressures exerted by trees through the soilestimated and measured dimensions of roots exerting a force on a structurecalculated total surface area of the roots exerting a force on a structurecalculated force exerted by roots per unit of surface area of structurecalculated total force exerted by roots of a given surface areameasured and determined volume of structureresearched and calculated mass of structuresdetermined impact of gravity on massdetermined effect of leverage on the forces exerted by tree roots on structuredetermined factors of root–soil matrix interactionsinvestigate area of contact between root and soilinvestigated elasticity, tensile strength and breaking stress of rootsinvestigated root cross-sectional morphologyassessed root plate for damage, deficiencies or defects that may contribute to tree failureestimated impact of static and dynamic testing for root plate stabilityevaluated possible root failure by root breakageevaluated possible anchorage failure by soil breakage or slippageinvestigated and assessed:effects of increasing massmethods for, and effects of, increasing the modus of ruptureeffects of use of curved structureseffects of soil mass and frictioneffects of use of anchors, braces and propscompiled investigations and assessments into reference portfoliocreated a report of potential tree damage to structure and provided design suggestions to mitigate damagereviewed root plate assessment, prepared final report on stability of tree and provided design advice to mitigate potential tree failurecreated an expert witness report on potential structure or tree stabilitydiscussed installation and protection measures with project personnelnegotiated and resolved anomalies in installation and protection measures.
Knowledge Evidence
An individual must be able to demonstrate the knowledge required to perform the tasks outlined in the elements and performance criteria of this unit. This includes knowledge of:
impact of soil on the stability and structural integrity of structures and trees, including:angle of repose of soil soil plasticitysoil moisture contentfield capacity of soileffects of soil moisture on soil cohesion and plasticity modes of soil liquefactiontesting soils for performance characteristics and soil stability, including:soil texturesoil cohesionsoil moisture and field capacityshear strength of soilsload bearing capacitycalculating mass of soil platetree root structures and their impact on soils and stability, including:root morphologyroot divisionroot distributionbuttressingspecies development of tap root systemsidentification of tree roots based on anatomical featurespressures exerted by tree roots, including:experimental modelling of tree root damagetesting tree roots impact on structures and soilsdirect and indirect forces and pressures exerted in soils by treestechniques and methods of estimating and measuring dimensions of roots factors of root–soil matrix interactionsarea of contact between root and soilelasticity of roots tensile strength of rootsbreaking stress of rootsroot cross-sectional morphologycalculations for determining forces exerted by tree roots, including:total surface area of the roots exerting forces on structuresforces exerted by roots per unit of surface area of structuretotal force exerted by roots of a given surface areameasurement of volume of structurescalculating the mass of structures and the impact of gravity on masseffect of leverage on the forces exerted by tree roots onto structuretree root health and condition and impact on tree stability, including:size of root plate and extent of root plate damageextent of root plate deficienciesextent of root plate defectsimpact of static and dynamic testing for root plate stabilitylikelihood of root failure by root breakage and failure of root platelikelihood of anchorage failure by soil breakage or slippageconsiderations of structural design and development, and tree support to mitigate potential tree or structure damage, including:effects of increasing mass of structureeffects of structure design and curvature of shape on strength of structureseffects of soil mass and frictioneffects of increasing the modus of ruptureeffects of use of tree support mechanismsAustralian standards relevant to trees on development sitesstructure designs for mitigation of tree damage and failuretree protection measurescreating reference portfolios of research and investigations, including annotations and calculationsdocumenting and reporting procedures, report preparation and communicating results of analysis, including:test results and assumptionsexpert witness reports, their purpose and designusing the correct language in reports and reporting fundamentals of the concepts, basic science and technology of structural engineering, construction and architecture as relates to arboriculture and impact of trees on structures.