The BS 5837 is still the current standard with regard to trees in relation to construction.
The preparation of this British Standard was entrusted to Technical Committee B/213, Trees, upon which the following bodies were represented:
Institute of Leisure and Amenity Management
Institution of Civil Engineers
Institution of Structural Engineers
National House-building Council
ODPM — Wildlife and Countryside Directorate
Royal Institute of British Architects (RIBA)
This article details changes from the 2005 edition and looks towards the upcoming review.
The 2012 revision has been found to be necessary to take account of current practice regarding planning for the management, protection and planting of trees in the vicinity of structures, and for the protection of structures near trees.
A New Standard
A significant commercial consideration for all parties involved in the planning application is that the standard suggests that the arboricultural method statement with the application be submitted simply as heads of termsas 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 greater input will be from the project arboriculturist to produce a suitably detailed arboricultural method statement, including an auditable system for monitoring a schedule of specific site arboricultural events on site. All parties need to understand this shift in the balance of the arboriculturist’s work profile compared to the requirements that have existed for the past 7 years under the 2005 release of the standard.
The 2012 standard states:
5.4 Arboricultural impact assessment
5.4.1 The project arboriculturist should use the information detailed in 5.2 [Constraints posed by existing trees] and 5.3 [Proximity of structures to trees] to prepare an arboricultural impact assessment that evaluates the direct and indirect effects of the proposed design and where necessary recommends mitigation.
5.4.2 The assessment should take account of the effects of any tree loss required to implement the design, and any potentially damaging activities proposed in the vicinity of retained trees. Such activities might include the removal of existing structures and hard surfacing, the installation of new hard surfacing, the installation of services, and the location and dimensions of all proposed excavations or changes in ground level, including any that might arise from the implementation of the recommended mitigation measures.
In addition to the impact of the permanent works, account should be taken of the buildability of the scheme in terms of access, adequate working space and provision for the storage of materials, including topsoil.
6 Technical design
COMMENTARY ON CLAUSE 6
Technical design [RIBA stage E, see Table 1 below] includes information sufficient to provide a high level of confidence in the outcome for trees retained on development sites. Where planning permission or other statutory controls apply, details might need to be submitted in draft form or heads of terms to allow for changes to the design that might occur after permission has been granted. In these cases, it will be necessary for the project arboriculturist to set out a series of parameters for construction activity (e.g. where service routes and/or construction activity should not occur), based on the RPA and the physiological needs of the tree, to which the finalized specifications and statements will apply.
6.1 Arboricultural method statement
6.1.1 A precautionary approach towards tree protection should be adopted and any operations, including access, proposed within the RPA (or crown spread where this is greater) should be described within an arboricultural method statement, in order to demonstrate that the operations can be undertaken with minimal risk of adverse impact on trees to be retained.
6.1.2 The arboricultural method statement should be appropriate to the proposals and might typically address some or all of the following, incorporating relevant information from other specialists as required:
a) removal of existing structures and hard surfacing;
b) installation of temporary ground protection (see 6.2.3);
c) excavations and the requirement for specialized trenchless techniques (see 7.7.2);
d) installation of new hard surfacing – materials, design constraints and implications for levels;
e) specialist foundations – installation techniques and effect on finished floor levels and overall height;
f) retaining structures to facilitate changes in ground levels;
g) preparatory works for new landscaping;
h) auditable/audited system of arboricultural site monitoring, including a schedule of specific site events requiring input or supervision.
6.1.3 The arboricultural method statement should also include a list of contact details for the relevant parties.