Examination of Witnesses (Questions 6560
- 6579)
6560. It is also possible, is it not, to move
around the uses which are undertaken by Mintel within their properties
so that you might be able to put particularly noise-sensitive
elements of the user into the property next door, which is 13
to 17, I think, Long Lane because that building has double glazing?
That would be possible, would it not?
(Mr Griffiths) It is not a question where you
can move people. That is not for me, but I think it is probably
for somebody from the operational side you will need to discuss
that with as to whether people have to be near each other and
so on.
6561. It is right to say, is it not, that there
is a dispute resolution procedure included in the proposed undertaking?
(Mr Griffiths) There is, yes.
6562. So if your client was unhappy with the
package that came forward, they could take that to dispute resolution
and the issues could be aired?
(Mr Griffiths) They could be aired. I think
the issue here is that at this stage Mintel are very concerned.
They know they are only 5 metres away from the construction site,
I have raised a risk and they do not want to be further down the
line—we have heard that pun before!—when Crossrail
is being built, for example, and they have then got very little
chance of having a reasonable settlement, so that is a concern
at that stage.
6563. You wrote a report for your client on
noise and vibration impacts related to Crossrail dated 16 September
2005?
(Mr Griffiths) Yes
6564. Am I right in saying that at no point
in that report do you recommend that relocation is necessary?
(Mr Griffiths) Yes, I think you are probably
right. That was in our initial review of the documentation.
6565. I am not probably right, Mr Griffiths,
I am right.
(Mr Griffiths) I absolutely take your word
for it.
6566. And if you had thought at that particular
point that relocation was necessary, having reviewed the information
provided, no doubt you would have recommended that to your client?
(Mr Griffiths) The title of that report is,
I think, a `critique', so we were looking through what had been
done and we were not necessarily giving recommendations, I do
not think.
6567. Thank you very much indeed.
Re-examined by Mr Newberry
6568. Mr Newberry: Mr Griffiths, let's
deal with the double glazing point first of all. You have put
the figure of 34 in?
(Mr Griffiths) Yes.
6569. That is the level of mitigation you expect,
and you have indicated that there are difficulties in getting
more than that because of the ratio of glass to brickwork in an
elevation?
(Mr Griffiths) Yes.
6570. Mr Taylor, for his part, said that you
could do it, that it could be overcome. What is your judgment
on the issue of whether you can increase noise attenuation by
glass, having regard to what he said on the one hand and your
view of the structure of the building and the relationship of
glass to brickwork?
(Mr Griffiths) My view is that there are two
issues. One is the ratio of windows to walls and, as I say, on
an office building, as we saw in the British Standard and in fact
as PPG24 states, the more area of window you have got, the lower
your attenuation. On the other hand, you could use thicker glass
in commercial buildings which would bring it back up, so I think
the two probably go hand in hand and probably the best you would
get is around 35, and that is a figure which Crossrail have put
in their mitigation package, that they would expect around 35.
6571. So this figure that you have used and
Crossrail appear to agree with, ie, getting to the order of a
34/35dB reduction, have you any idea where this sudden change
comes from, a jump from 34 to 40, which was being suggested to
you?
(Mr Griffiths) No. The only way I can see it
is if you look at the manufacturer's data and the test data which
are from a test laboratory say you can get levels of sound reduction
of about 40dB or so reduction. The difference is the practicality,
as I said before, the actual installation of when it is installed,
the way it is installed and so on where inherently on the practical
side you get less than that.
6572. From your understanding of the Crossrail
documentation, notwithstanding what Mr Taylor has put to you,
have you seen any Crossrail documentation which supports the contention
that they can suddenly jump from 34 to 40?
(Mr Griffiths) I have not seen any figure—
6573. Was any document shown to you?
(Mr Griffiths) No, nothing to say 40.
6574. Let's look at the issue of vibration,
if we may, and I wonder if that passage which Mr Taylor referred
to could be put back up again. It was paragraph 2.3.11.[63]
That was talking about the vibration levels which you have used
of a hydraulic breaker which are predicted to be in the region
of 1.5 to 7.
(Mr Griffiths) Yes.
6575. First of all, in relation to the cruncher
which has been referred to, where does that figure in the range
of 1.5 to 7? Is it under 1.5?
(Mr Griffiths) No, I would not say it was under
1.5. At the end of the day, it is the impact of breaking a building
and I have measured crunchers on a number of occasions and there
is still a certain amount of impact. You would probably still
have to use a hydraulic breaker maybe to start with and then a
cruncher can then come in, so it would probably be lower, I would
have thought, than 7, so it would be nearer 1.5 to 3. I would
have to look at the figures which are available in the British
Standard.
6576. Well, a figure was not put to you, but
you think between 1.5 and 3?
(Mr Griffiths) I would have thought so, but
I would like to check that.
6577. Is that a figure, the 1.5 to 3, in terms
of the occupier, in your judgment, that is acceptable?
(Mr Griffiths) No, totally unacceptable, having
witnessed 3 myself.
6578. I want to understand the inference that
maybe being drawn from this passage which your attention has been
drawn to. We know that at other times on the site a breaker is
not being used, that that particular operation may have ceased,
and you identified all the bits of kit which are being used throughout
the 4½ years. Is there anything to suggest that, when a breaker
is not being used, the vibration levels will not be above 1.5
or is that the only time we need to be concerned about vibration?
(Mr Griffiths) I would still have some concern
over the oscillatory rotary piling. It is a good method, a better
method for vibration, but when you are that close, within a few
metres from a building and there is a piling grid, there has to
be some risk just because they have to push the casing into the
grid, and there must be, I do not know, 40 or 50 piles going along
the building to make the wall.
6579. Perhaps we will explore with the other
Mr Taylor what is meant by these various mitigation measures,
but if this is to take place out of hours, is the consent of the
local authority required for that?
(Mr Griffiths): Yes, there will need to be
consent of the local authority, yes.
63 Crossrail Environmental Statement Technical Report,
Assessment of Noise and Vibration Impacts, Volume 4 of 8, Central
Section, Noise & Vibration, para 2.311, http://billdocuments.crossrail.co.uk
(LINEWD-STR112-074). Back
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