1.
Introduction
1. BS 5837:2012
Trees in relation to design, demolition and construction – Recommendations
(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
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.
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
|