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 89 Vic, Graving Dock—Report of Engineers. 751
3 Westminster Chambers, London, S. W.,
and Greenock, Scotland,
October, 1874.
To the Honourable Chief Commissioner of Lands and  Works,  Victoria.
Sir,—We have the honour of submitting for the information of the Lieutenant-Governor
in Council, the following Report on the subject of the proposed Graving Dock to be built in
Esquimalt Harbour.
In accordance with instructions received on the first of July, through the Government
Agent, G. M. Sproat Esq., of 4 Lime Street Square, London, our Mr. Morris left England ns
early as possible and arrived in Victoria on the twenty-sixth of September, when, as requested,
he reported ourselves to the Honourable Provincial  Secretary.
The object of our visit to Victoria being to report as tu the best site for the construction
of a Graving Dock in Esquimalt Harbour, the obtaining particulars as to the nature and cost of
building materials, the price of labour, and making definite arrangements of terms for professional services about to be rendered in connection with the proposed Graving Dock at Esquimalt.
in the event of the works being proceeded with.
We proceeded, in company with yourself, immediately on our arrival, to inspect the
Harbour of Esquimalt, and on that and other occasions, have very carefully examined the
various sites at all suitable for the construction of the proposed Graving Dock. We have to
acknowledge your kindness in furnishing us with all the particulars you possessed relating to
the Harbour, as well as supplying as with local information which we have found most valuable,
and enabled us, with the aid'of the borings and soundings which had been already made, to
report earlier than we could have done had we to acquire information without your assistance.
There are several sites which offer more or less favourable advantages for the construction
of the proposed Graving Dock, viz :—" Dunn's Nook," " Thetis Cove," at the north-west end
of the Harbour ; " Plumper Bay," or a Cove a little to the south of the last mentioned, and
which is overlooked by the Indian Village ; " Lang's Cove," and " Thetis Cove," adjoining the
Navy Yard.
"Dunn's  Nook."
On account of the limited area between the two sides of the bay or nook, the amount of
rook blasting that would be necessary, and the absence of the requisite material for cofferdam
purposes, we cannot recommend the above site as being the one where the Graving Dock could
be constructed with the smallest possible outlay.
By reason of borings having been made both at "Lang's Cove" and at "Thetis Cove"
(Navy yard) we propose on this account to compare the relative, advantages which the two sites
offer for the economical Construction of the proposed Graving Dock ; but before doing so we
would remark that the nature of the banks and foreshores of the two sites, viz., " Thetis Cove "
to the north-west of the harbour, and the adjoining Cove are almost identical with " Land's
Cove" in regard to having a flat foreshore running out some distance from the banks before
reaching the required depth of water at low water; judging from indications we have observed
we feel we are safe in assuming that the nature of the foundations would be about the same in
the above-mentioned sites as at " Lang's Cove;" therefore the comparison about to be made
between the cost of constructing a dock at " Lang's Cove " and " Thetis Cove," (Navy yard)
will equally apply (from the similarity of conditions), and hold good as between the cost of constructing the Graving Dock at "Thetis Cove," north-west side of harbour, or the adjoining
site, and " Thetis Cove," (Navy yard).
After careful consideration we beg respectfully to state that we are of opinion that
'• Thetis Cove," adjoining the Navy yard, should be the site selected for the construction of the 752 Graving Dock—Report of Engineers. 1876
proposed Graving Dock. The cost of executing the works at this site would, in round numbers, be
nearly £18,000 less than in the most favourable position it could be placed in, in " Lang's Cove "
(see Drawing No. 2, attached to this Report), or about £33,000 less than if the Dock were constructed in "Lang's Cove" in the position shewn on Drawing No. 1, also attached to this Report.
The following particulars will, without the necessity of going very minutely into details, be sufficient, we think, to show clearly the advantages in the matter of cost of constructing the Dock at
" Thetis Cove," (Navy yard), over that at "Lang's Cove," and also over the similar sites at "Thetis
Cove," north-west side of harbour, and the one adjoining to the south, already referred to.
"Lang's Cove" Site.
Drawing, No. 1.
The length of cofferdam required at this site, as shown on drawing, will be about double
that which would be necessary at " Thetis Cove," (Navy yard).
The length of quay walling would also be about double that required at the selected site.
A very large amount of earth filling would be necessary to form ground all round the
Dock to a level of six or seven feet above high water mark, and for a width of probably one
hundred feet on each side of Dock (at " Lang's Cove ") upon which to erect the requisite
buildings and workshops; whereas at the selected site, about two-thirds of the ground is above
high water mark, the remaining one-third forming a convenient place for depositing the excavated material from the Dock.
At " Lang's Cove " it would be necessary to purchase in the vicinity clay land to obtain
the necessary clay to form the cofferdam, and probably would have to be brought some little
distance; the clay could not be conveniently obtained from the site as it is from ten to twenty
feet below high water mark, and, furthermore, is covered with sand and shells for a depth of
eight or nine feet which would have to be removed before the clay was reached, whereas at the
selected site it is on the spot, and could be readily obtained out of the excavations required for
the Dock.
Again if Dock were constructed in the position shown, the entrance works, inverts, &c,
would have to be carried down through five or six feet of sand and shells beyond the required
depth to reach the solid clay, upon which to found the works, involving an  unnecessary outlay.
Cost of pumping may be considerably increased over that at the selected site on account
of the much larger area enclosed, and for which some allowance must be made.
" Lang's Cove" site presents one favourable feature over the selected site, that is the land
upon which the Dock would be built being covered at high water, belongs, we presume, to the
Government and, of course, be free of cost; not so the land at "Thetis Cove," (Navy yard),
which is held by private individuals.
"Lang's Cove" Site.
Drawing No. 2.
On drawing No. 2 the position of the Graving Dock is shown considerably nearer the
land than in the former case, the head of Dock about touching the bank which is three or four
feet above high water mark. We will now consider the merits of this site under the proposed
altered circumstances, and compare ii with the selected one.
The length of coffei dam will now be only one-fourth more than that required at the
selected site.
There will be about one hundred and twenty feet more of quay walling than at the
selected site.
The amount of earth filling round the Dock, to a level of six or seven feet above high
water mark, upon which to erect the requisite buildings and workshops will be very considerable.
There will still be the necessity, as in the former case, of purchasing, in the vicinity,
clay land, but to a less extent, for obtaining the requisite clay for forming the cofferdam.
The site being covered at each time of high water, will belong to the Government and,
therefore, be free of cost.
It will be necessary to dredge an approach or channel-way to the entrance of the Dock
for a length of about 200 yards, to reach the requisite depth of water, and from seventy to
ei°hty yards wide, and of an average depth of about eight feet.
Pumping, though  less than  in the previous case, will still be more than at  the selected
With the exception of the extra amount of work in the foundations, at entrance works,
and inverts, which has been mentioned as necessary if the Dock were constructed in the position 39 Vic. Graving Dock—Report of Engineers. 753
shown on drawing No. 1, and which will be taken into consideration in its proper place; we
may, for matter of comparison, safely assume that the body of the Dock, viz., inverts bottom,
side walls, &c, will be the same in each case, after making the allowance for extra depth above
referred to; therefore it will be only necessary to compare the various items under the different
heads to obtain the difference of cost of constructing the Dock at each site, and under the conditions assumed.
" Thetis Cove " Site,  (Navy Yard.)
£     s d
Cost of constructing a Cofferdam, 400 feet long, complete ,	
Bight acres of land, at £, per acre, being probably double its value, aud taken to allow
ample margin	
Quay wall, 250 feet long, at an average cost of about £— 5$ lineal foot	
Filling round Dock for erection of buildings and workshops	
"Lang's Cove "Site.
Drawing No. 1.
Cost of Cofferdam, 800 feet long, including the getting of clay and wheeling it the same
distance as at the selected site	
Quay wall, 650 feet long, at an average cost of £— per lineal foot	
83,260 cubic yards of filling round Dock and appioaeh road, in reclaiming 100 feet in width
of ground round Dock, and a fifty feet width of roadway, @ — ^ cubic yard 	
Cost of purchasing clay lands, say	
Cost of extra depth of foundations at entrance for aprons and inverts	
Probable cost of extra pumping required at this site over the selected one, say	
" Lang's Cove " Site.
Drawing No. 2.
£     s d
Cost of Cofferdam, 500 feet long, including the getting of clay and wheeling it the same distance as at the selected site	
Quay wall, (deducting 150 feet for entrance) 350 feet long, at an average cost of £— ^ lin. ft.
41,583 cubic yards of filling round Dock, in reclaiming about 100 feet in width of ground on
each side of Dock, for buildings and workshops, @ — ?p cubic yard	
Cost of purchasing clay land, say	
48,629 cubic yards of dredging to form approach or channel-way to Dock entrance, @ — ^ c.yd
Allowance for extra pumping	
Cost of four dolphins to mark channel-way	
From the foregoing estimates it will be seen that the proposed Graving Dock could be
constructed at " Thetis Cove" (Navy Yard) for £17,317 sterling less than in the most favourable position in which it could he placed in " Lang's Cove."
As will be inferred, there will he about the same difference in cost in favour of the selected
site over one either in " Thetis Cove " on the north-west side of the harbour, or in the adjoining
cove to the south of this.
We now beg to report further and particularly upon the selected or " Thetis Cove " site
(Navy Yard). .
We may remark that the locality possesses many advantages, but at the same time it must
be borne in mind that such an important work as a deep graving dock should have for its foundation a stratum of which there cannot be any doubt as to its compactness and degree of hardness,
even although it may be composed entirely of clay.
The one great difficulty in dealing with a site like this is the large outlay which must be
incurred in the construction of a Cofferdam capable of resisting such a head of water of between
30 and 40 feet; and in this case it does appear that the only way to carry out the works in a manner that could 1-3 depended upon, with as little risk from bad workmanship, is by clearing the
whole site of water before any operation in connection with structural works are commenced.
This done, every opportunity will be afforded for sinking trial pit.' and ascertaining, definitely,
whether the clay is sufficiently compact .for such & ^crt.    This information could la obtained 754 Graving Dock—Report of Engineers. 1876
during the progress of the wharf or quay wall, and would be of a most valuable description,
enabling us to design the Dock foundations with a degree of certainty which could not be
obtained under other conditions, and thus avoid the risk of any great excess of cost on the one
hand or want of strength or stability on the other. Had it been possible to have procured a
site of solid clay, where the ground had not been more than two or three feet above high water
mark, the entire cost and risk of erecting a Cofferdam would have been avoided, but in such a case
there would probably have been a very large amount of material to be dredged which would cost
more to remove than that for the erection of the dam. Although there are many advantages in
cutting out of the solid ground, the fact must not be overlooked that a large amount of excavated
material would probably have to be removed and deposited at some considerable distance from
the works. As regards the Cofferdam, when once the water is successfully shut out from the site
of the Dock a considerable saving would be effected in excavation, in not having to remove a
large amount of material from the intervening, sloping space between the Cofferdam and the
back ground at the level of high water mark, and probably equal to about one-third or one-
fourth of the total amount of excavation. There is also another great advantage, and that is,
that a place for the deposit of excavated material can be had contiguous to the works.
Upon the whole, it is most desirable that the works, especially in a port like Esquimalt,
where appliances for submarine works are difficult to obtain, and expensive to work, that the
whole of the works should be executed dry. It is for this reason that we propose that the water
should be shut out from the entire area, so that, immediately on the completion of the dam, the
quay walls on each side may be proceeded with, and carried on continuously, with the advantage
of the work being carried on under immediate supervision.
It was a question with us whether any system of making concrete blocks, in order to avoid
the cost ofa dam, could be carried out with more economy and expedition than with a Cofferdam.
Even although this system were used, it would do no more than shorten the dam at its shore
ends, where it is of small height compared with the centre portion opposite the entrance, and,
therefore, is a matter hardly worth consideration; for, under any circumstances, a dock situated
as this is, a deep water dam would have to be erected across the entrance, and of sufficient
length, with return ends, to include abutment and wing walls. Had the quay wall been of sufficient length to have warranted the purchase of the necessary and costly plant for constructing
and setting concrete blocks, unquestionably that would have been the more expeditious mode of
constructing the quay wall; but, at the same time, a wall of such a construction, having open
joints below low water mark, through which water would pass and circulate, would, to a considerable degree, add to the danger and the risk of the water following round the back of the
walls of the Dock, and adding to the increase of springs, which would not be the case where a
wall is built on a good, solid, dry foundation, with a good, solid, Ashlar face jointed in cement,
and backed up with cement rubble concrete.
The position of the Dock, having a fair-way line of entry from the harbour, with the absence
of any dangerous rocks on either side of such line, coupled with the great depth of water, and,
further, with the effectual shelter by the high ground surrounding the Cove from prevailing
winds, renders the site selected, from this and the other reasons stated, the best in the harbour
of Esquimalt.
It is of immense importance, and of considerable advantage, that a Graving Dock should
he protected from prevailing winds, for it is not unlikely that during docking of ships of great
tonnage, light, and standing high out of the water, that great risk is incurred of vessels drifting
on to the side altars of the Dock, and damaging not only her bilges, but also the Dock. This
often occurs where vessels are docked and the number of hands employed are inadequate. In
large establishments, where any number of men can be brought to assist upon an emergency, such
risks are reduced to a minimum; hut in a dock worked or let out for repairs in the manner this
Dock may be, the Government, for their staff, would not have more hands about the premises
than a Dock Superintendent, Engineer, and Stoker, it being the general custom for parties hiring
public docks to employ as few men as possible, and, to our knowledge it has frequently happened
that a breeze has sprung up at the time of docking, in a dock exposed to winds from all quarters,
and ships have been driven against the stone altars, damaging both themselves and the dock :
and for this reason we consider the site selected, on account of its shelter, is comparatively free
from such risks. The above objections do not so forcibly apply where the prevailing winds are
from head to stern of dock, or vice versa; therefore the lesser shelter afforded by the ground at
the head of Dock will not be so detrimental to the working of the Dock had the Dock been
exposed from the side. All things considered, the sheltered position is very favorable for docking operations. 39 Vic. Graving Dock—Report of Engineers. 755
Had the site not been so sheltered there would have been an absolute necessity in so limited
an area to have erected probably two lines of dolphins of very heavy construction, at distances
of 100 and 200 feet on each side of the fairway channel leading to the Dock, to prevent vessels
of great length swinging and grounding on the rocks inside the cove, and as there are not any
tugs of great power at present in use at Esquimalt, this danger will be all the more increased;
but probably in actual working all that may be found necessary will be to lay down say four or
five heavy screw moorings or warping buoys every 100 feet, for a length of 500 feet on eaoh
side of entrance leading well out into the harbour, and having a width between them of about
150 feet
Estimate op Cost.
With reference to the cost of the proposed works, we have made as close an approximate
estimate as we are able to do in the absence of working drawings, and we beg to say that we are
of opinion that the Graving Dock can be built at ' Thetis Cove' (Navy Yard) for the sum of
, provided no circumstances of an unusual and
unlooked-for character arise during the execution of the works ; and, further, this sum will allow
of the construction of two caisson chambers and vertical walls to Dock, to permit its being used
as a wet dock, if desired, but provides for only one wrought iron caisson.
The above sum is exclusive of charges for engineering and superintendence.
Sand  and Shingle.
Seeing that in the construction of the Graving Dock, which we propose to be chiefly of
rubble concrete, probably representing nearly five-sixths of the whole structure, it is of great
importance that suitable sand and shingle should he obtained.
We have found in the different nooks and bays in the harbour of Esquimalt, more or less
quantity of shingle, and we have every reason to believe it can be had from the foreshores in
sufficient abundance for the work; if not, ballast or shingle can be easily obtained in the
vicinity by sifting the ordinary soil; beach sand, mixed with broken shells, can be had in
abundance; if it cannot be obtained free of broken shells by excavating below the surface, then
other suitable sand can he had in the vicinity, from Craigflower and other places.
As to the rubble to be used in the cement rubble concrete, almost any quality of stone
having a fair degree of hardness, and of a non-absorbent nature, is suitable for this purpose. W e
propose to use the stone that will be taken out of the excavation, and to blast from the adjoining
high, rocky ground on the west side of the Dock, which can be run down by gravitation on to
the works, or stone may be obtained from various sources in the locality.
Granite Quoins.        ' .
We believe there is not a quarry opened up anywhere on Vancouver, or any other adjacent
island, from which suitable granite can be obtained for the stop quoin faces, etc., at entrance of
Dock. We inspected some granite at ' White Stone Point" in Saanich Inlet, hut it is of such a
quality and so broken up that no reliable stone of any size could be had, not even if expense was
incurred in opening it out.
We learn that where granite has been used at all, in the vicinity of Victoria, it has been
obtained from the granite boulders which, here and there, have been found distributed in different
parts of the country, and are now getting very scarce, and hardly he justified in relying upon
this doubtful source of supply, and which, when found, would he, from what we hear, uncertain
in quality, and wanting uniformity of colour; under these circumstances, we are of opinion that
the granite for the stop quoin faces of the inverts and sides of caisson berth should be of first-
rate quality; Aberdeen or Dalbeattie, worked at quarry, packed and shipped out ready for setting
in place. This, we believe, will be the most judicious, and probably the least costly mode of .
proceeding. Even although granite may be found in the district, yet, on account of the small
quantity required, it would not pay to take the risk of opening up quarries, which could not be
done except at great cost, and in fact a larger outlay would most likely be incurred in the
removal of the top beds, before reaching sound stone, than what it would cost to send the stones
from England; further, it would require skilled men, accustomed to work in granite, which, for
invert stones, must be accurately done; therefore the best course, as above suggested, is for
these stones to be worked under inspection in England aud sent out. 756 Graving Dock—Report of Engineers. 1876
Ashlar, Altar Stones, die.
We have visited and made a careful examination of the quarries from which stone
can be obtained, more or less suitable for plain Ashlar work. The Thetis Island stone
appears to be a very fair quality for building purposes, is easy to work, and we are
informed will harden by exposure to the weather; this, we need hardly say, is a good
quality for a stone to possess. The stone from the Newcastle quarry (from the upper
bed or stratum) which is of a hard and compact nature, in our opinion, should be used
throughout the works for copings, timber, slides, steps, altars, &c, and for the Ashlar
work generally. In drawing up the contract for the permanent works we shall reserve
to ourselves the right of using the Thetis Island stone, in portions of the work, should
we deem fit.
The bricks at Mr. Mason's yard are of a quality somewhat better than we expected
to find them, and as the whole of the invert foundations, caisson chambers, &c, where
watertight work is required, no material is so eminently suitable, both for strength and
watertight work, as Portland cement brickwork; and if a little more care is bestowed
on their manufacture, to make a brick having more the character of a clinker than of a
well-made brick suitable for house building, a greater degree of hardness would be
obtained, though at a loss of shape; bricks of this class are well suited for the reception
of cement joints.
It is most desirable that for a harbour situated like Esquimalt that a caisson, embodying all recent improvements, should be adopted, and especially such an one as would
be, not only simple in its construction, but economical in its working.
We, therefore, propose the adoption ofa similar caisson to that recently erected, and
now in successful operation, at Greenock, since January of the present year, and has
proved, most conclusively, the many advantages to be obtained by a sliding caisson and
folding bridge over a caisson of ordinary construction.
It has been found that a large outlay, for labour alone, in opening and closing has
been saved at Greenock; and, further, all risks from damage by ships fouling is entirely
avoided, and there is not the great anxiety on the part of the Harbour Master, who has
not only the responsibility of shifting the caisson in heavy weather but also of attending
to the shoring of vessels during the time they are taking the blocks on a falling tide.
At a port where high class labour is expensive it would appear eminently advantageous to adopt a caisson of the above description, for although when in adjustment and
in order it can be hauled in and out of its chamber in three minutes, and if by chance it
should happen that the hauling machinery gets deranged (which is practically impossible)
the caisson could be easily floated in and out precisely in the same manner as an ordinary
caisson during the time of repair to the machinery.
In a dock of more than 350 feet in length, its facilities for the repairing of vessels
may be greatly increased by the addition of a second caisson; at all events, at Esquimalt
thei*e is some argument in favour of making provision for such during the course of
construction of the dock, which can be done at a comparatively small increase of cost;
this is recommended not so much on account of the immediate advantage to be obtained,
but from the fact that a wrought iron caisson after a few years requires an overhaul,
painting, &c, and if the second caisson is off the same moulds as the one at the entrance
they could be used alternately when required. Under such an arrangement, facilities
would be had for repairs, &c, which cannot be conveniently obtained where the tidal
range is so limited as at Esquimalt; of course caissons could bo careened, but this would
entail the removal of the permanent Portland cement ballast on the floor of the caisson;
such an operation could only be done at considerable cost, and loss of time and revenue.
With the aid of the second caisson, the lower end of the dock could be used for vessels
requiring short repairs, and in the upper end vessels could undergo extensive repairs,
re-plating, &c, which could not be done except with the aid of the second caisson, without, as in a case of re-plating of, sinking the vessel.
There is also another great advantage, which should not be lost! sight of in a port
cr harbour like Esquimalt, which bids fair (should the railway ci the island oe constructed) of rising to considerable important., and that is that the upper end of the
dock could be especially designed ?,n~ used for pontoon purposes, by pamping water in 89 Vic. Graving Dock—Report of Engineers. 757
to a level of, say, five or six feet above high water mark, giving sufficient depth to float
a raised pontoon on to an area or platform constructed for their reception; by this
arrangement, it will be seen that any vessel at the head of the dock could be lowered or
raised without interfering with a vessel in the stern of the dock.
Berth for pontoons cannot be made at the lower end of dock, without sacrificing
good shoring altars, for high vessels.
It will also be seen that, in the case of working the upper end of ihe dock on the
pontoon system, or in the case of docking small vessels by the introduction of the second
caisson, the cost of pumping at each docking operation will be considerably reduced.
All things considered, it would appear advisable to make the dock in the first
instance of the minimum length stipulated by the Admiralty, which is four hundred feet.
This would enable the dock to be carried out of such a length that not only could provision be made at the lower end for vessels of about three hundred and fifty feet in
length, but the masonry ot the second caisson could be included; and with the future
requirement for vessels of greater length it would be easy to extend the dock another
two hundred feet in length at a minimum cost, for the second caisson will take the
place of a cofferdam, and thus enable any extension to be executed without flooding
of works at every docking operation.
In the event of the Government determining not to provide for a second caisson, the
chamber constructed for the reception of the one at the entrance could be used as
a place for the repair and painting of the caisson, by the formation of grooves in the
sides, at entrance of chamber, for the reception of balks of timber to form a temporary
cofferdam. Under any circumstances, we consider this provision absolutely necessary,
for no better provision could be made for inspecting and repair of caisson than this.
It may be mentioned that, with a dock of such magnitude as proposed, it might be
of some advantage to use it as a wet dock on a small scale, for probably there would be
times when it would not be required for repairing purposes, it might then be very useful
for landing purposes. The caisson, as proposed, will admit of the dock being used either
as a wet or a graving dock, which, as far as we know, has never been done except at
the Greenock Dock; and for this reason it would be extremely useful to provide vertical
walls, at distances of say eighty feet apart, against which vessels might lie and unload;
these projections will be protected by fenders.
We have, &c,
(Signed)       Kinipple & Morris.


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