AIA and AMS

1.            Introduction

1.         BS 5837:2012 Trees in relation to design, demolition and construction – Recommendations [1](referred to hereafter as BS5837) offers guidance to all the professionals involved with and interested in trees and development, it is not a specification.   The Foreword of BS5837 states, on page iii,

It has been assumed in the preparation of this British Standard that the execution of its provisions is entrusted to appropriately qualified and experienced people, for whose use it has been produced.

2.         This guidance note seeks to explain the scope and extent of the arboricultural impact assessment and the arboricultural method statement and when in the development process such documents are required.

2.            Terms and definitions

3.         The text that follows in italics is taken from BS5837:

For the purposes of this British Standard, the following terms and definitions apply. 

3.2 arboricultural method statement

methodology for the implementation of any aspect of development that is within the root protection area, or has the potential to result in loss of or damage to a tree to be retained 

3.3 arboriculturist

person who has, through relevant education, training and experience, gained expertise in the field of trees in relation to construction

3.4 competent person

person who has training and experience relevant to the matter being addressed and an understanding of the requirements of the particular task being approached

NOTE A competent person is expected to be able to advise on the best means by which the recommendations of this British Standard may be implemented.

3.6 construction exclusion zone

area based on the root protection area from which access is prohibited for the duration of a project

3.7 root protection area

layout design tool indicating the minimum area around a tree deemed to contain sufficient roots and rooting volume to maintain the tree’s viability, and where the protection of the roots and soil structure is treated as a priority

3.11 tree protection plan

scale drawing, informed by descriptive text where necessary, based upon the finalized proposals, showing trees for retention and illustrating the tree and landscape protection measures

3.            Arboricultural impact assessment

1.         Under paragraph 5.4 of BS5837 the project arboriculturist is recommended to use the information available to evaluate the direct and indirect effects of the proposed development upon the tree stock and to prepare an arboricultural impact assessment.   If mitigation is available that will lessen the adverse impacts of the development upon the tree stock then that should be explored and proposed in the arboricultural impact assessment.

2.         The arboricultural impact assessment should be fully rounded, taking account of the effects of any tree losses that may be required to implement the design, and any potentially damaging activities proposed in the vicinity of retained trees.   The assessment should not restrict itself to the consequences of the permanent works that are identified in the development proposal but should also consider those measures that may be taken whilst the works are in progress (temporary access routes, working space, storage and so on).

3.         The ideal arboricultural impact assessment will include

1.         the tree survey plan and schedule with the trees selected for retention, pruning  or removal clearly identified, and an evaluation of the impact of any proposed losses, and 

2.         a review of the constraints that the trees selected for retention will impose upon the development, and

3.         a draft tree protection plan that indicates the precise location and extent of the various tree protection measures that are to be implemented, including the measures proposed for protecting areas of future planting, and

4.         the issues that will need to be addressed by an arboricultural method statement.

4.            Arboricultural method statement

1.         The arboricultural method statement will adopt a precautionary approach toward tree protection and any operations, including access, proposed within the RPA (or crown spread where this is greater) should be described in order to demonstrate that they will have a minimal adverse impact upon the trees to be retained.

2.         An arboricultural method statement will typically consider some or all of the following:

·         the removal of existing structures and hard surfaces

·         the installation of temporary ground protection measures

·         the required excavations, including the needs of specialized trenchless techniques

·         the installation of new hard surfaces, including the nature of the materials, design constraints and implications for levels

·         any specialist foundations that may be required – installation techniques and the effect on finished floor levels and overall height

·         any retaining structures required to facilitate proposed changes in ground levels

·         preparatory works for new landscaping

3.         In addition the arboricultural method statement will incorporate an auditable system of site monitoring, including a schedule of specific site events requiring the project arboriculturist’s input or supervision.

5.            Timing

1.         Under BS5837, in order to retain significant trees on site, the developer and the local planning authority will require:

·         good quality, well considered, tree-related advice given at the right time, and

·         clear and logical ways to implement the advice, and

·         adequate control measures to ensure that no  harm comes to features to be retained.

2.         In BS5837 the time when the arboricultural advice is required has been mapped onto the Royal Institute of British Architects (RIBA) work stages: the arboricultural method statement that is submitted with the application is to be submitted simply as heads of terms, an acknowledgment that the detail of the application may change as it is considered by the local planning authority.   Once planning permission has been granted then the project arboriculturist will be expected from to produce the full arboricultural method statement.

3.         The table below is taken from Annex B of BS5837 and refers to the nature and level of detail of information required of the project arboriculturist at particular stages of the planning process:

Stage of process	Minimum detail	Additional information
Pre-application (RIBA Work Plan stages A – D)	Tree survey	Tree retention/removal plan (draft)
Planning application (RIBA Work Plan stage D)	Tree survey (in the absence of pre-application discussions) Tree retention/removal plan (finalized) Retained trees and RPAs shown on proposed layout Strategic hard and soft landscape design, including species and location of new tree planting Arboricultural impact assessment	Existing and proposed finished levels Tree protection plan Arboricultural method statement – heads of terms Details for all special engineering within the RPA and other relevant construction details
Reserved matters / planning condition	Alignment of utility apparatus (including drainage), where outside the RPA or where installed using a trenchless method Dimensioned tree protection plan Arboricultural method statement – detailed Schedule of works to retained trees, e.g. access facilitation pruning Detailed hard and soft landscape design	Arboricultural site monitoring schedule Tree and landscape management plan Post-construction remedial works Landscape maintenance schedule

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[1] BSI. 2012. BS 5837:2012 Trees in relation to design, demolition and construction – Recommendations. British Standards Institution, London, UK