Improvements in or appertaining to Dams for Retaining Water.
Year: 1890

page_text: Date of Application, 16th Jin., 1890
Complete Specification Left, 16th Oct., 1890-Accepted, 22nd Nov.. 1890
PROVISIONAL SPECIFICATION.
Improvements in or appertaining to Dams for Retaining Water.
I, THOMAS THOMSON of Blennerville, Tralee in the County of Kerry, Ireland, Civil
Engineer, do hereby declare the nature of this invention to be as follows:
11
This invention is designed as an additional precaution against leakage in dams,
by giving a means whereby any leak can be quickly discovered before it has been
allowed to penetrate through the entire dam. The apparatus can also, in some cases,
be itself a means of greatly strengthening the dam.
In any dam formed of earth, clay, stone, solid masonry, or a combination of these,
(with or without piles of wood or iron or other material or other framework) for the
retension of water, I place longitudinally in the dam, preferably somewhere near the
centre, transversely, a hollow wall of metal, or, in rare cases and for temporary
purposes, of wood.
I construct each side of this hollow wall preferably of metal plates, riveted or
bolted together, and I well brace the two walls together by means of metal or other
struts. This hollow wall is preferably carried up from the very lowest foundation to
the top of the embankment, and from the bottom of this hollow wall I carry an outlet
culvert through the outer part of the embankment or through a tunnel to one side of
the embankment. The plates forming the side wall nearest the water can be provided,
at intervals, with weeping holes fitted with door valves or otherwise. The hollow wall
can, in some cases, be made to give additional strength to the dam at the expense of
further inspection by filling in between the said hollow wall with masonry, concrete,
or puddle, thus forming a solid structure. This, however, should only be done as a
last resource, in cases where the dam requires considerably strengthening, and there
is no other practical method of doing it.
In order to keep the iron structure from corrosion, I prefer to put a thick layer of
asphalt or other non-corroding, non-oxidising, and waterproof material between the
iron and the embankment, and firmly adhering to the iron. The inside of the iron
wall can, of course, be kept painted or tarred. This iron structure can, if desirable,
take the place of or be an auxiliary to the puddle wall. The outlet culvert from
the iron structure must be made big enough to take away every possible leakage into
the same.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in or appertaining to Dams for Retaining Water.
I, THOMAS THOMSON of Blennerville, Tralee in the County of Kerry, Ireland, Civil
Engineer, do hereby declare the nature of this invention and in what manner the
same is to be performed, to be particularly described and ascertained in and by the
following statement :-
This invention is designed as an additional precaution against leakage in dams, by
giving a means whereby a leak can be quickly discovered before it has been allowed
to penetrate through the entire dam. The apparatus can also, in some cases, be itself
a means of greatly strengthening the dam.
The invention may be described as follows, reference being had to the accompanying
drawings, in which,
Figure 1 is a transverse section of a dam constructed in accordance with my
invention.

page_text: Figure 2 is an elevation on an enlarged scale of a portion of the inner face of the
hollow iron wall shown in Figure 1.
Figure 3 is a sectional plan of a part of said wall.
Figure 4 is a transverse section of the wall as constructed of brick, and
Figure 5 is a plan of Figure 4.
A, is a dam formed of earth, clay, stone, solid masonry, or a combination of these,
either with or without piles or framework of wood, iron or other material. B is a
hollow wall of metal or of brick or stone work, or even, in rare cases, of wood. This
hollow wall is located longitudinally in the dam and runs preferably from end to end
thereof, at or near the central plane of the dam as seen in Figure 1, being strongly
braced and supported so as to form a box girder.
The sides of the hollow wall are constructed preferably of metal plates 6 riveted or
bolted together as, for example, by means of angle irons 6', and the sides are well
braced together so as to form a girder by means of metal or other struts 6². The
plates forming the side of the wall nearest the water to be retained are preferably
provided, at intervals, with weeping holes ³ which may be fitted with door valves or
otherwise as desired.
The hollow wall B is preferably carried up to the top of the embankment from the
very lowest foundation, as from the line a which represents the substratum of rock or
other impermeable material, a' being the ground line. From the bottom of the wall B
an outlet culvert or culverts C is or are carried through the outer part of the dam or
through a tunnel or tunnels to one side thereof. This culvert is for the purpose of
draining off any water leaking into the wall B, and it is made large enough to pass
the greatest amount of leakage water which can possibly enter said wall.
In order to keep the iron structure from corrosion, I prefer to put a thick layer D
of asphalt or other non-corroding, non-oxidising, and waterproof material between the
iron and the embankment, and firmly adhering to the iron. The inside of the iron
wall can, of course, be kept painted or tarred. This iron structure can either take
the place of or be an auxiliary to the ordinary puddle wall E.
When constructed of metal, either cast iron, wrought iron or steel may be
employed. For situations where, from the nature of the ground, there would be
much liability to movement, wrought iron or steel would be preferable. It would
also be advisable to use curved or dished plates, so as to allow for a small amount of
distortion.
For small dams, that is, those having comparatively little height, brick or glazed
blocks F, Figures 4 and 5, with asphalt joints f, may be employed for constructing
the hollow wall, suitable cross walls f¹ being provided as struts, as in the case of
the iron wall. Such a structure may be made at a comparatively small cost,
and it is much more permanent than iron structure, not being liable to corrosion.
For temporary purposes and for work in foreign countries, it may frequently
be found more advantageous to employ timber in the construction of the hollow
wall aforesaid.
The hollow wall B can, in some cases, be made to give additional strength to the
dam at the expense of further inspection by filling in between the said hollow wall
with masonry, concrete or puddle, thus forming a solid structure. This, however,
should only be done as a last resource, in cases where the dam requires considerably
strengthening, and there is no other practical method of doing it.
A dam constructed with a hollow wall such as above described is open at all times
to inspection, the leakage water is readily drained off, and a leak may be detected and
the dam repaired before said leak has time to cause any serious damage.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. A hollow wall constructed in or near the central longitudinal vertical plane
of a dam and provided with a culvert or culverts adapted to drain off the leakage
into it.

page_text: 2. The hollow wall and appurtenances, constructed substantially as and for the
purposes herein described and illustrated.
Dated this 15th day of October 1890
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.