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Helton Brid 12 Boar Logoilome
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ing in mass the dam.
(13) In the case of the Tytan Dam, the late Sir Robert Rawlinson K.C.B., directed numerous small drains to be formed in the mass of the concrete behind the inner lining of masonry intended to be water-tight, in order that should any water find its way through the said lining it would flow freely away, and not accumulate in any fissure or cavity, causing an upward hydrostatic pressure, tending to reduce the stability of the structure. I consider that this would be a wise precaution.
In the case of Tytan it was not however adopted, because those in charge of construction thought that the concrete would be sufficiently porous, to prevent any such prejudicial accumulation.
As a matter of fact, the Tytan dam leaks considerably through the mass of the concrete. I maintain that concrete should be impervious, the interstices between the stones being completely filled with mortar. Percolation through concrete tends to its disintegration.
Mr. Mansergh informs me, that in the case of the Birmingham Dams, he is not draining the whole mass of the concrete, in the manner recommended by the late Sir Robert Rawlinson, but he is taking every precaution to render the whole mass absolutely homogeneous and impervious.
The only drains which he introduces, are to remove the land springs, in the excavations for the foundations, and he has also provided a single drain, at a low level, below the whole length of the Dam, to remove any water which might by chance percolate through the water phase, below the foundations, and this drain communicates with the out-let culvert.
(14) The surface of the drainage area should be as little disturbed as possible, the natural growth of herbage
Page 201
200
3400
IN ONLARA
M
bimme Misw atuam ond to ndguel ont
wing oful 15 57
NNA TONDAY
#
#
MAS
.Alay to " 33%cnoRIN
,000 by Brit
(0.0)
Helton Brid 12 Boar Logoilome
2* Mandamebe nude boRESTO
stressor giftub referentes to
Po suo d
34700042 3 Tend
At a Treo od zn
2400% 1000 to dug DTA
J
S
se va end pale dneveqTONTA TEDA
AUTORILE $40
* A SA
4
.DA”-19Jey puligatoris
די
Fun vol wwwd
d hluosta JNATNO LIA
ing in mass the dam.
(13) In the case of the Tytan Dam, the late Sir
directed numerous small drains
Robert Rawlinson K.C.B.,
to be formed in the mass of the concrete behind the inner lining of masonry intended to be water-tight, in order that should any water find its way through the said lining it would flow freely away, and not accumulate in any fissure or cavity, causing an upward hydrostatic pressure, tending
I consider to reduce the stability of the structure. that this would be a wise precaution.
lation.
Perco-
In the case of
Tytam it was not however adopted, because those in charge of construction thought that the concrete would be suf- ficiently porous, to prevent any such prejudicial accumu-
As a matter of fact, the Tytan dan leaks considera-
I maintain that bly through the mass of the concrete. concrete should be impervious, the interstices between the stones being completely filled with mortar. lation through concrete tends to its disintegration.
that in the case of the Birming- Mr. Mansergh informs me, ham Dams, he is not draining the whole mass of the concrete, in the manner recommended by the late Sir Robert Rawlinson, but he is taking every precaution to render the whole mass
The only drains absolutely homogeneous and impervious.
found
Drainage area
not to be disturbed.
which he introduces, are to remove the land springs, in the excavations for the foundations, and he has also provided a single drain, at a low level, below the whole
to remove any water which might by length of the Dam, chance percolate through the water phase, below the founda- tions, and this drain communicates with the out-let culvert.
(14) The surface of the drainage area should be as little disturbed as possible, the natural growth of herbage
5
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