The Hawaiian star. [volume] (Honolulu [Oahu]) 1893-1912, 1907-04-24

begin to take the form and body of a
dam, as the important foundation work
is practically finished.
RECOMMENDATIONS.
l will briefly review the changes in
plan which 1 have hitherto touched up
on and recommend:
First-Increase the height of the dam
from crest elevation of 1923 to elev
| 1898, increasing the capacity 60 per cent
Second-Change the plan of spillway
to a channel parallel with the side Of
the reservoir, extending the length of
the overflow lip to 300 feet, giving a
capacity of 1000 sec-ft. with a rise of
IT. and doing away with movable flash
boards and foot bridge.
Third-Move the rock fill portion Of
the dam ten feet makai, filling the
space between the rock fill and the
redwood core wall on top Of the con-
crete wall with selected clay, rammed
in place, and puddled with water next
to the core wall. This filing should
start about feet below the top of the
concrete part of the wall and extend
to the top.
Fourth recommend that the pipe
through the core wall on the Waikiki
side already in place is of no service
as no water can reach it. The trench
being filled with impervious material
all percolation to the head of the pipe
is cut off
Fifth-Install a two-stage centrifugal
pump and engine with capacity for
pumping three cubic feet per second to
height of $50 feet for sluicing pur-
| poses
Sixth-Omit the marginal excavation
around the reservoir provided for in
the original plans, estimated at 10000
cubic yards and costing $780, The
evident intent of this marginal excava-
ton was to provide against the growths
which accumulate in shallow water
around the margin. This would be an
excellent provision if the reservoir were
always full, but as the working level
of the water will be below the depth of
excavation planned the conditions
sought to be avoided would still pre-
vail at the lower levels. Hence it APP
pears to be a useless expense to make
such excavation.
Seventh-To provide for securing as
large a proportion of freshet water as
possible from the Lulumahu stream
think the dimensions of the ditch for
| 4
erably increased. AS the ditch is only
about 425 feet long the expense of en-
larging it is not very great. 1 have
made no estimates on this point as
the necessity for the diversion is not
immediate further than to carry the
low water flow, which the sluice-ditch
will convey for some years to come
The original estimate for this diversion
was 1920. The diversion of the Maole
stream by pipe and tunnel is also a
matter for subsequent consideration
and construction, and does not enter
into the estimates for the Nuuanu Dan
for the present. The cost of the Maolt
diversion by a tunnel 900 feet long ant
1900 feet of 16-inch and 1S-inch woot
stave pipe with branch of 12-incI
pipe, 1000 feet long, was estimated by
Mr. Walker at $13,6SOOO.
Eighth recommend most empha.
tically that the sliucing operations be
pushed to the utmost to the end thai
all material possible to be moved by
that process shall be so moved, and
that practically all of the earth from
Station 4.75 to the Waikiki end, ex.
cept that at the mauka toe now being
deposited by cars to the extent of 46Ot
Gu. yds. be put in place by sluicing.