The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1906-08-18

found there was a space from g inch t
81 inch between the pipe and the con
| crete along the lower a of the section
| these conditions show that this concrett
| armor can IN NO SENSE BE CON
| SIDERED \ WATER TIGHT cos
DUIT The proportions OF the coa
/ crete were one cement. three Of sane
and five of gravei: tGe proper pro 3or
tions for concrete of this thickness
put in with expanded metal would bt
about one cement, two sand and three
gravel. II the wooden pipe had been
considered in the sense of form an6
the concrete made thick enough to
| form a proper conduit, it would have
proved a good construction.
VALVE TOWER:
@The cross-eut under the washout
pipe before referred TO, which showed
| a soft plastic material in the bottom,
| and the soft material in the core trench
| (termed MUSHPILE) at Station
| 8+75, which Indicated the same ma
| terial in the bottom, led ME to believe
/ that the congiomerate mass of boulders
| and decomposed rock composing the
/ bench on which the valve tower stood
was uniformly underlaid with this same
material, accordingly, | had a tunnel
run in under the large boulders to the
corner of the valve tower and pit
sunk 6 feet below the bottom of the
| foundations into the plastic material;
| then ran a rod down to a depth of
| IL feet, making a total depth of IL
feet below the foundation, which by
comparison with the core wall trench
found was within one foot of the
| rock Under ordinary conditions this
would be considered safe founda-
ton as the weight of the tower per
square foot comes within the pre-
scribed limit of safety; but consider
ing the porous nature of mass over
the plastic material per cent. of
which IS soluble in water, and the
DISASTROUS EFFECT of even
slightest settlement of the tower
which world crack the connections
with the pipe, together with the adj
ditional strain on the tower during
construction, | do not believe it safe
to leave the tower there unless the
foundation was carried down to solid
rock, which would cost more than to
remove it, and substitute a different
construction.
The engineer states that the tower
was placed here in preference to the
toe of the dam, to secure better
foundation and a shorter bridge. ms
vestigation has shown the foundation
to be no better and the cost of the
bridge is of minor Importance. There
is the further objection to the pro-
posed plan of placing an intermediate
inlet in the tower with horizontal
section of pipe which would be liable
to leakage from settlement and sub
ject to decay by being empty when
water was at a lower level.
GROUND WATER AND DRAINAGE.
In a country situated as this is, with
a heavy RAINFALL with heavy deposit
of drift material upon the permanent
bed of the valley, there will neces-
sarilv be a considerable amount of
ground water uniformly seeking an
outlet throughout the cross section of
the valley. In such cases the move
ment win of necessity be through the
most porous material, varying along
the lines of least resistance, toward
the thread of tbe valley. The surface
conditions at the dam site show a
large seepage towards the side draws |
notably the draw above the dam on
the Eva side, where l had cut. made
into what is called an old spring, and
the large draw on the Waikiki side, |
Immediately below the dam Here
seepage appears for a considerable dis |
tance along the edge of the hill near
the bottom of the draw.
An examination of the material in |
the core trench ON the Waikiki side
discloses an irregular strata of porous |
material with a thin strata of vol |
canie sand everything a more imper
vious material. Water is found com
ing into the trench through this |
porous material and also small |
stream on station HISS through a /
assure on the maiki makai] side of |
trench On the Eva side of the !
dam, the porous material and strata |
of volcanic sand is encountered in the |
trench everything pronounced strata
of plastic material which is coTapara-
lively water tight. In the construc
ton the water entered the trench all
the way Immediately over the plastic
material until the accumulated flow at
station S+99.5 was forty-five gallons
per minute.
At the cut before referred to, in
the draw on Eva side at upper toe
of dam, the same plastic material
was uncovered about five feet below
the surface with the water running
out into the trench through the vol
canic sand Immediately over the plas-
tie formation. The investigation of
these conditions shows a continuous
underlying strata of ground water at
an average elevation of go feet
There is also some water passing
through the porous formation in the
bed of the stream over the hard rock
/ Do NOT CONSIDER IT
BE SAFE TO CONSTRUCT
A DAM ON THE PROPOSED PLAN.
The approximation from the ground
water, after being cut off by the core
wall, would accumulate IL the outer
'lope and render. ii unsafe Such a
'aturation established within the out I
II slope would be a serious element
If danger. 5
The puddled trench and core wall at /
'ither end of the dam, passing through /
he porous rock and volcanic sand to a {
Connection with the plastic formation
viii cut off the seepage,
r bo 70 I Z