Examination of Witnesses (Questions 2600
- 2619)
2600. Thank you. Just so that we can have this
clear before we move on to consider your evidence, can you briefly
summarise the Promoter's position as to the demolition and construction
works at number 38?
(Mr Morton) Surprisingly,
the Promoters have only looked at one situation, which is the
retention of the façade of the building. I am quite amazed
at that because certainly if a project like this was put before
us, as a company of engineers, we would look at all aspects of
it (a) to provide the best economic solution to the solution that
had arisen and (b) to properly advise our clients as to the alternatives
that might be available to them. The report that I have draws
a conclusion that the only way of dealing with the site is the
demolition of the building because they put up an enormous scaffold
around the building itself and then say, "We have not got
enough room to construct the shaft because we have not got anywhere
to put things on the site, this enormous scaffold that is retaining
the façade is in the way".
2601. I know that you have considered the Promoter's
position. Can you please say what your response is in general
terms to the Promoter's position?
(Mr Morton) What I have
tried to do is to look at this as a project that came to us. The
way I see it at the moment as far as the Promoters are concerned
is they have not been properly advised as to the possibilities
for the use of this site. I think it should be further investigated
down the path I have taken which is to put forward three alternative
proposals which can be looked at individually and assessed and
decisions made.
2602. Thank you. We are up to about paragraph
13 in your note. Can I ask you to outline what the position is
as far as those three options you mentioned are concerned?[17]
(Mr Morton) The first option
would avoid the need for any alteration to number 38 at all. The
second and third would enable the building to be left substantially
intact. All would involve only very minor changes to the Promoter's
proposals being based largely upon changes to the construction
methods. None of the methods I propose are unusual or would be
unduly onerous or expensive. They are intelligent but straightforward
solutions to enable Crossrail to be built as planned without demolishing
38 Charterhouse Street. They would provide sufficient working
space on the Fox and Knot Street site and not require the works
to be carried out other than in a wholly safe manner.
2603. I am going to ask you to explain what
is involved in the first option that you put forward and in particular
in relation to the construction techniques involved.
(Mr Morton) I think probably
rather than read this I ought to explain to you and perhaps I
can get you to visually understand what is involved. We are digging
a big round hole and in digging that hole as you dig it, you have
to hold its sides in. There is a system of doing this by putting
piles around the periphery of the hole. Initially you put pairs
of piles—I am sorry, are you looking for something?
2604. Mr Binley: Yes. I would find it
easier if I saw the options in front of me, quite frankly. I am
sorry, Chairman, but I am finding this slightly difficult.
2605. Mr Honey: There is one drawing
which will help illustrate and that is at tab 7. Before describing
what is shown here, can you just describe what the Promoter is
promoting by way of construction techniques?
(Mr Morton) There are several
ways of constructing a big hole like this. The Promoter is proposing
to construct this by effectively digging a ring around the area
where they are going to need to construct the walls, in other
words a circular ring, which is over width about a metre wider
than the actual hole itself. They place concrete blocks at that
sort of depth in segments all around the outside. They possibly
put another row of these segment blocks around on top of those
and, having got to that position, they put concrete around the
periphery so it gives the wall at the top some stability and excavate
underneath these segments to put further blocks underneath and
go down that way. So you are building underneath what you have
already constructed the whole time. The risks associated with
that are that you loosen the earth behind the wall and thus you
have to carry out grouting which is the pouring in of a cement-based
mixture to solidify the ground around the outside of the hole.
This has a risk of settlement on adjoining building associated
with it because the ground almost certainly will consolidate during
this period, but of course properly done the risks are quite small.
They go on down with this system until they get the 22 metres
down, which is about 75 feet. At the bottom of that they spray
concrete on to the further digging that is taking place to hold
the earth up beneath this secant pile system. They rely on that
as the structural means of retaining the earth and they then construct
from that the entrances to the adits that take the people down
on to the railway track.
2606. You have an alternative proposal which
is illustrated on the screen at the moment.
(Mr Morton) Yes.
2607. Please can you explain what is involved
in your alternative proposal?
(Mr Morton) If you look
at the plan you will see there are a series of piles, a series
of tubes that are shown around the periphery, which is what is
called a secant pile system. Initially you pile every second pile,
you leave a gap between them. You then come along and put another
pile down between them and on the inside face you build a block
wall to consolidate the whole structure. You drive those piles
down to the requirement that you have and excavate from inside
the waste materials that you do not want any more. That would
probably be done by having a small digger dropped into the hole
doing the excavation and removing the earth. Again, when you get
to the bottom you will have a different form of construction which
would almost certainly be a sprayed concrete system.
2608. Comparing the need for working space on
the site between the two methods, which would be better?
(Mr Morton) The secant pile
system needs a rather wider area for its construction overall
because you have the block work lining it. I am not aware of the
thickness of the segment system but there is a difference. Marginally
the shaft would be of somewhat larger diameter.
2609. How about working space needed on the
site in terms of the storage of materials and so on?
(Mr Morton) In due course
I would have to refer to the proposals to retain the façade
because that significantly affects the construction overall related
to storage on the site. In my view this system would not require
any more storage space than the segment system. With the segment
system it is suggested storage space on site for the segments
that are going to be immediately used and in the case of the piling
system you would not have those segments but you would have tubes
and reinforcement on the site ready to go down into the various
piles.
2610. To your knowledge, is this system for
building shafts related to rail works being used elsewhere?
(Mr Morton) Yes indeed.
Scanmoor tell me they are working on such a shaft and putting
forward proposals in Shepherd's Bush.
2611. Having regard to the options you are putting
forward in order to avoid the complete demolition of this building,
what is your first option?
(Mr Morton) The first option
is to move the shaft some two metres. That is something of a guess,
but something of that order in the direction of Fox and Knot Street.
This means that it impinges on Fox and Knot Street rather more.
One of the arguments put up against this is possible services
in Fox and Knot Street but the comparatively quick investigation
that Scanmoor did suggests that there is a sewerage line on the
far side of Fox and Knot Street, although there does not seem
to be anything of significance on our site side.
2612. Are there any barriers to moving the shaft
some little distance towards Fox and Knot Street?
(Mr Morton) Not that I am
aware of.
2613. Will it have any effect on any other buildings
in terms of increasing the need for acquisition?
(Mr Morton) No, it certainly
will not.
2614. I understand that using this system there
is also a second option. Can you please explain what that is?
(Mr Morton) The second option
is as shown on the drawing. That uses piles flattening out one
side of the ring in the way that is shown on the drawing. If that
is done, it is my opinion that we could get away without even
taking down our enclosing wall to the building at 38.
2615. I understand that there is a third option
where, even if you accept absolutely everything that the Promoter
is proposing, you do not believe it is necessary to demolish the
building. Can you please explain what would be involved in those
circumstances?
(Mr Morton) In working on
historic buildings, one is always looking for a solution. You
are prepared to go to any lengths to design a solution to save
that building. What I have done here is say to myself, "Okay,
the chips are down. We cannot do anything else. We have to accept
some loss of this building. What can we do about that?" I
looked at the photographs.
2616. The photographs are to be found in your
tab six. Is it the last photograph in there?
(Mr Morton) Yes.
2617. Please explain by reference to that photograph.
(Mr Morton) If you look
at that photograph, you will see at first floor level there are
two windows. Alongside those windows in the retained part of the
building there is a brick pier. You can simply remove that section
of the building to the right of that pier. It is a structural
line across the building. It has beams across the floor at the
upper levels. You could take that section out and rebuild it afterwards.
The only difficulties, if they are difficulties, are the slight
complications of replicating the cornice and pilasters on the
front elevation. Exactly the same situation applies on the elevation
on the other street. If you simply take that off, it would give
you an extra three metres of building site area to work in. It
seems to me to be a much better alternative to total demolition
of the whole building.
2618. Has Crossrail, the Promoter here, considered
anything similar to that at all?
(Mr Morton) They have indeed,
in their report.
2619. The drawing is tab five, the last drawing.
Can you explain first what this drawing is and where it comes
from?
(Mr Morton) This is related
not to trying to save the whole building but to restraining the
two long walls at their ends so that work could be carried out
to build the shaft without taking the ends of those walls down.
The odd thing is that what has been proposed—please understand
this is totally related to facade retention—is only taking
out the wall in the ground floor. Then they comment on that that
it is not really practical because you still have the building
above you and you cannot get at it. They have looked in a sort
of way at one of these proposals but then dismissed it.
17 Committee Ref: A35, Alternative construction plans
for Fox and Knott Street (SCN-20060207-015 to 021). Back
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