Terry O’Regan examines some of the finer points of trees in relation to design, demolition and construction as captured in BS 5837:2012
In my preceding article ‘What is a Tree?’ (Horticulture Connected, Spring 2018) I promised that I would elaborate on how to build on the resource that is BS 5837:2012 and also, share some of my misgivings about the standard. Before moving on to my elaboration and misgivings, I would, first of all, urge all of you to consider the dirty, wriggley, unseen, underground rooty bits in the thoughts called up by my simple ‘What is a tree?’ question. This is vital if we are to take BS 5837 seriously.
For those still in the dark, BS 5837:2012 covers trees in relation to design, demolition and construction.
Some years after I qualified with my degree in horticulture from UCD, I received a phone call from Leo Curran, my botany lecturer. He was interested to know what my thoughts were on my experience of the degree course in UCD. I told him that I thought the course lost sight of first principles far too early in the process. Experience in the real world had forced me time and again not to refer to the mass of data that had been churned out at me, but to go back to first principles for answers.
By the early 1990s, as I began to realise that the day to day practice re-landscape and landscaping in Ireland was a blundering fiasco, I saw the need for a clear policy and strategy approach. And again when I became engaged with the European Landscape Convention in the mid-1990s I saw the vital necessity of having a coherent structured approach to tackling serious issues. My subsequent work in SE Europe and Kosovo in particular reinforced my conviction that one must clearly set out one’s stall at the start of any strategic document and keep the core objectives in mind at all times throughout the process.
“The planner who in the majority of Irish local authorities has no qualified tree professional to consult may all too easily be hoodwinked”
In my experience, BS 5837:2012 does not stand up to scrutiny. It’s not a perfect publication, but it does potentially provide a common ‘hymn sheet’ for all involved in design, demolition, construction and development planning to sing from, and a basis for working together towards a better outcome for the present and future tree population.
With regard to working together, it is worth noting that the foreword to the standard states that BS 5837 “provides recommendations and guidance for arboriculturists, architects, builders, engineers and landscape architects. It is also expected to be of interest to land managers, contractors, planners, statutory undertakers, surveyors and all others interested in harmony between trees and development in its broadest sense.” That is reasonably all-embracing if a bit limp and uncertain in tone. I would respectfully suggest that those who should turn to BS 5837 for recommendations and guidance should include all of those politely invited to find the standard ‘of interest’ especially the planners, statutory undertakers and surveyors.
British Standard 5837:2012, Trees in relation to design, demolition and construction – Recommendations is at 50 pages, not a large document. There is a temptation to cherry-pick and rush to the handy bits that will make a planning submission sound good. Place ‘In compliance with BS 5837:2012’ in a prominent location on the ‘landscape’ drawing, along with plenty of tree symbols. Add a few paragraphs under the heading ‘tree survey’ with references to root protection areas. Insert a statement somewhere that all existing healthy trees will be retained. Provide a tree protection plan with promised protective barriers indicated and illustrated. Whatever you do, don’t show any tree symbols on the services drawing where sewers, drains, kerbs and hard surfaces are probably slicing left and right through root protection areas.
“There is a temptation to cherrypick and rush to the handy bits that will make a planning submission sound good”
The planner who in the majority of Irish local authorities has no qualified tree professional to consult may all too easily be hoodwinked – especially if they already have been told that BS 5837 may only be of interest for them!
THE STRENGTHS OF BS 5837:2012
I suggest that the standard is an important step forward in attempting to provide an integrated guide to the issue of trees in proximity to buildings and structures old and new.
I particularly like Figure 1 on page 2 entitled ‘The design and construction process and tree care’ where the tree survey is right up there at the beginning of the project with the topographical survey, and trees have an integrated role all through the subsequent process.
The clear guidance on the measurement of the root Protection Area (RPA) is an advance on the old ‘dripline’ guesstimate.
For me, the tree categorisation method and cascade chart is a qualified strength in that it does provide some sort of basis for a common categorisation approach.
THE WEAKNESSES OF BS 5837:2012
I have already described one weakness in the fourth paragraph above where I suggest that there is a lack of clarity and understanding about who the standard is aimed at. The ‘Terms and Definitions’ would appear to be on the short side, bearing in mind that the majority of the target audience that one would hope to reach has had little or no professional training on trees. There isn’t even a definition of a tree.
The introduction fails to adequately set the scene for the standard. There is a reasonably useful section banished to Annex A, puzzlingly entitled ‘General advice for other interested parties’.
In my opinion, this ‘hidden’ piece of text should be central to the introduction. And to prove my point, in my earlier article an excellent piece on the ‘Extent and form of the root system’ is shivering at the outer edge of Annex A – A.2.2 – the authors of the standard patently did not have much time for the dirty, wriggley bits. I’m very uneasy about table A.1 in Annex A where it states, ‘Minimum distance between young trees or new planting and structure to avoid direct damage to a structure from future tree growth’. If there is one lesson I have learned over the past 50 or more years it is to think very carefully about where you plant a tree in relation to structures, be they walls, roads, paths or buildings. The said table provides a range of minimum distances that seem irresponsibly close in my experience. It is difficult to reconcile the advice in this table with the radii of RPAs in table D.1 on page 40.
I have noted that the RPA is a strength, but the standard fails to stress that this is the very minimum area that might reasonably be expected to secure the long-term survival of a retained healthy tree. In fact, much of the standard is dedicated to providing excuses for incursions into the RPA.
I mentioned above that the tree categorisation method and cascade chart is a qualified strength. I also have to view it as a weakness as it results in reports that are not easy to read and comprehend.
The term ‘Construction Exclusion Zone’ in section 5.5 of the Tree Protection Plan rings bells with me and sounds off sirens in a manner that ‘Root Protection Area’ could never match. Yet ‘Construction Exclusion Zone’ is not even a heading in bold in the document.
I suggest that there is a strong case to be made for the players and stakeholders in the relevant sectors in Ireland to produce an Irish standard for trees in relation to design, demolition and construction using BS 5837 as a starting point, but my lifetime experience tells me that this will take many years. In the interim, there is patently an urgent need for a continuing professional development programme to inform and train all players and stakeholders in the responsible application of BS 5837:2012. ✽
|TERRY O’REGAN, B Agr Sc Hort (Hons), FILI, MIoH, founder of Landscape Alliance Ireland has served the landscape industry in Ireland for some 45 years and advanced the intent and aims of the European Landscape Convention for some 20 years.
He now divides his time between providing landscape consultancy services in Munster and working as a Council of Europe international landscape and heritage expert in Kosovo. He continues to promote and refine his ‘jargon-free’ landscape circle methodology and is currently leading a pilot study on its use at local and regional administrative levels in Kosovo.