bs5837

[Chris at eden]

I think the point that's been missed on this thread is that is modification of the RPA actually down to you to determine?

 

Don't get me wrong, we don't know the spec of your survey brief, so it may be the case that you've been asked to give such info, bit if not, and you've just been asked to carry out an impact assessment and do a tree constraints plan, then of course you are only really there to report on the trees that are on site from a purely factual and unbiased perspective.

 

RPA modification is something that you could cover in secondary info, such as within an Arb method statement, and then be left up to the architect/engineer/planner to argue.

 

I guess what I'm trying to say is just be careful that you're not getting drawn into acting outside of your remit, and inavertantly get embroiled in the stuff that should/could be down to the other parties in the development process.

 

I know of several 5837 surveys that have been rejected by LPA's, purely on the basis that the arb surveyor was clearly not impartial within the report.

 

 

You can't modify the RPA at the method statement stage. The RPA is a constraint so should be used to determine the layout. It not the same as the offset rule either. Its designed to reflect onsite restrictions such as roads. I.e. you don't get roots under roads.

 

If you changed the RPA at the method statement stage that would most likely be after consent had been given. Not to mention you may not need an AMS. The LPA won't allow this.

 

When you submit the AIA to the LPA the plan that should accompany is a draft tpp. Not the TCP, that is for the design team.

 

No offence intended.

[Andy Clark]

You can't modify the RPA at the method statement stage. The RPA is a constraint so should be used to determine the layout. It not the same as the offset rule either. Its designed to reflect onsite restrictions such as roads. I.e. you don't get roots under roads.

 

If you changed the RPA at the method statement stage that would most likely be after consent had been given. Not to mention you may not need an AMS. The LPA won't allow this.

 

When you submit the AIA to the LPA the plan that should accompany is a draft tpp. Not the TCP, that is for the design team.

 

No offence intended.

 

None taken Chris.

 

To clarify, I didn't mean for the RPA to be modified within/by the MS......

 

The point i was trying to make was more that the subject of "the ability to modify the RPA" could be just be referenced as secondary info within the report - for the architect/engineer/planner to follow up on - rather than for the report writer trying to determine modification; which I understood as the question being asked by the op

 

[Chris at eden]

None taken Chris.

 

To clarify, I didn't mean for the RPA to be modified within/by the MS......

 

The point i was trying to make was more that the subject of "the ability to modify the RPA" could be just be referenced as secondary info within the report - for the architect/engineer/planner to follow up on - rather than for the report writer trying to determine modification; which I understood as the question being asked by the op

 

 

Ahhhh, I think I see where you are coming from. Are you saying that if an impact is identified which could be resolved by off setting you could amend at the AMS stage? That is pretty much what I did in the example I gave, so yes I agree. Although I did it at the AIA stage and didn't refer to it as offsetting.

 

I thought you were talking about the required modifications such as to reflect the position of roads, buildings, level changes, etc. My mistake. Cheers for clarifying.

 

I've seen so many plans where the RPA's are plotted 10m into the footprint of an existing house.

[kevinjohnsonmbe]

I think the point that's been missed on this thread is that is modification of the RPA actually down to you to determine?

 

Don't get me wrong, we don't know the spec of your survey brief, so it may be the case that you've been asked to give such info, bit if not, and you've just been asked to carry out an impact assessment and do a tree constraints plan, then of course you are only really there to report on the trees that are on site from a purely factual and unbiased perspective.

 

RPA modification is something that you could cover in secondary info, such as within an Arb method statement, and then be left up to the architect/engineer/planner to argue.

 

I guess what I'm trying to say is just be careful that you're not getting drawn into acting outside of your remit, and inavertantly get embroiled in the stuff that should/could be down to the other parties in the development process.

 

I know of several 5837 surveys that have been rejected by LPA's, purely on the basis that the arb surveyor was clearly not impartial within the report.

 

Straying a little bit off topic, as ever, but whilst there are experienced opinions engaging the subject, could I seek a view on the nature of a 'purely factual and unbiased' report and what, where, who decides that the arb report should be this way?

 

This is a general question rather than directly relating to the circumstances the OP has raised.

 

There's no confusion over the factual recording and required detail / content of the various reports as described in 5837, but so far as I can see, there is no 'limit' to that which might be included so that could include opinion or options?

 

(I have in mind the H&S officer that walks around the site telling everyone what they can't do but not offering any advice or guidance on a safer / better option as a comparison) Not very helpful....

 

Since the author of a report has presumably been engaged to provide (a) a record of that which exists on that day and may influence design and (b) wether through offline discussions with the design team, engagement with the LA and the developer / customer, a set of options that might inform and assist the ultimate aim of the development, is it considered 'correct' simply to record the data and pass it back to the customer, or is it considered better to suggest solutions?

 

Probably a bit too broad a question to result in a simple yes / no answer - I guess it'll depend what you've been asked / paid to do......?

[Paul Barton]

Some Arb consultants advertise their "% success rate" with planning work i.e bs5837 style surveys and reports. I wonder whether they just refuse to work for clients with unworkable design proposals?

 

Let's remember, when you're engaged by a client to do a pre-development tree survey (and possibly the AIA and AMS) you are being engaged as one element in a process which has one primary aim: to get planning permission! So, I would certainly suggest solutions where appropriate.

 

I find the main problem with this work is that the client (and sometimes the LA) either don't know what they need or give a very vague instruction.

[daltontrees]

I think a simple way of understanding RPAs is that the only one that can cause the RPA to deviate from circular is the tree.

 

Encroaching on the natural extent of the RPA is a different matter that must be justified. An RPA modified in this way is strictly speaking not called an RPA in the British Standard. Unfortunately no alternative name is given. What should happen is for the natural RPA to be split into (i) parts not to be touched (these go into the Construction Exclusion Zone), (ii) parts identified as compensation for unavoidable encroachment into the natural RPA (these too go into the CEZ) and (iii) parts of the natural RPA unavoidably affected temporarily or permanently by construction and development. The last group are then addressed in the AIA and AMS in terms of what disruption there is and what needs to be done about it.

 

Wasn't the 10% discretonary offset a feature of BS5837:2005 which no longer exists and is now 2012?

[Chris at eden]

I think a simple way of understanding RPAs is that the only one that can cause the RPA to deviate from circular is the tree.

 

Encroaching on the natural extent of the RPA is a different matter that must be justified. An RPA modified in this way is strictly speaking not called an RPA in the British Standard. Unfortunately no alternative name is given. What should happen is for the natural RPA to be split into (i) parts not to be touched (these go into the Construction Exclusion Zone), (ii) parts identified as compensation for unavoidable encroachment into the natural RPA (these too go into the CEZ) and (iii) parts of the natural RPA unavoidably affected temporarily or permanently by construction and development. The last group are then addressed in the AIA and AMS in terms of what disruption there is and what needs to be done about it.

 

Wasn't the 10% discretonary offset a feature of BS5837:2005 which no longer exists and is now 2012?

 

Yes it went with the 2005 standard and it was 20%. Mainly because consultants were offsetting into areas where there would clearly be no roots. Now its at the discretion of the consultant and TO but I see no reason why you cannot encroach slightly as long as you can justify it based on site conditions. Some LPA's are more open to this than other in my experience.

[daltontrees]

Yes it went with the 2005 standard and it was 20%. Mainly because consultants were offsetting into areas where there would clearly be no roots. Now its at the discretion of the consultant and TO but I see no reason why you cannot encroach slightly as long as you can justify it based on site conditions. Some LPA's are more open to this than other in my experience.

 

Yeah, just found my old 2005 BS during clearout just now. It seemed to allow a 20% offset if if it was deemed tha tthe tree could tolerate it. As such the offsetting was a decision to accommodate design, not to reflect tree troot morphology. No wonder it was abused and had to be changed!

 

Hope the OP has got it now. The 20% discretion no longer exists. Offsetting needs to be justified, and work in the resultant RPA has to be approved separately to production of TCP.

 

The fundamental test seems to be "the minimum area around a tree deemed to contain sufficient roots and rooting volume to maintain the tree’s viability" (citing BS5837:2102 section 3.7). I don't see how any LPA could reasonably refuse minor encroachments if that test is satisfied.

[Philip Anderson]

Hi all,

 

Can you off set the rpa on a bs5837 report?. I know it was in the old bs, but it doesn't state you can or cant in the latest bs.

Just wondering as I recently was asked to carry out a report, but the rpa is with the planned development,(which is a extension to an outbuilding).

The old rpa offset would have been enough to make a difference.

 

any help is always greatly welcomed

 

I think you mean the planned development is within the RPA ,it's up to you to justify the case for an encroachment and mitigate it if you feel it is justifiable ,that's why they are employing you as a consultant,the problem was with the old 20% some developers who I worked with banked on using this 20% as development space!wether the tree needed it or not.

[tree79]

Hi all

Think I have it sorted now, I know the offset was in the 2005 and not the new bs. Think by all your posts as long as I can justify and work within the rpa I should be fine ( within reason of course)