Saturday press. [volume] (Honolulu, H.I.) 1880-1885, 1884-05-10
HoNolulU WAFER supply.
a letter from an Engineer.

aDlc 10 your ttauetss i nave therefore Ncntufeu
to offer few opinions and statements bearing
on the subject. based on data collected for
several years past.
The public Of Honolulu have long been
aware that the city water supply has been made
quate to the growing demand. AT each sue
cessive meeting Of the legislature of the county
their hopes have been raised by promises only
to be mdely dissipa,ed, and at each recurring
dry period notices greet them limiting the use
Of the water for which they pay pretty roundly.
Not only is our water supply limited in guam
tity, but bad in quality, and II any curious in
dividual wishes TO ascertain why this is So, let
him walk from Nuuanu reservoir along the line
Of supply, and he will return satisfied on that
point
will proceed to make a brief statement OF
the situation, embracing our present sources Of
supply and how utilized, together with notice
Of our available sources and the means OF
utilizing them in various ways.
Nnnam pdliy Sntbiy. AT poin, about
a,soo fee, beyond the Halfway House, in the
bed OF the river, there heads an open conduit or
auwai, known as Pak Auwa From this
point, a, an elevation above the sea of SSi feet,
there flows volume Of water, the minimum
quantity, as measured in dry times, being 4
cubic feet per second or, supposing possible
diminution, say cubic feet per second. Civ.
ing I,o3S,SI6 U. S gallons in "a hours. This
water flows along the auwai, subject in its
course to sources Of contamination, overgrown
distance of abou, miles, when it empties into
a small so.called filterng reservoir, at an ev
vation Of 37S feet. The available distance
between the two points for pipe line being
o,4o6 feet, the least grade on which would be
Ala per cent. Your mathematical friends can
now calculate the size Of pipe to convey the
above quantity OF water. remembering that the
pressure in said pipe, with the above head of
SSrfeet less 37Sfeet, equals 500 feet, which would
not be the hydostatic pressure due to the height
Of that column Of water, but what is known
as the hydraulic pressure, or that due TO the
vertical distance oil the lowest part Of pipe line
below the hydraulic grade-the pipe icing
an open one for the reason that no distribution
under pressure is required above the reservoir.
Tnconnection with this, Twill statethat 5.inch
pipe is distributed for laying along great por-
ton of the line, which, under the conditions
as above, would convey a supply of about
o,633,6 600 gallons in "a hours. | will not now
discuss the reasons why this enormous supply
was provided for between these points.
The so-called fltering reservoir has a total
superfces Of I43 square yards, but is not used
for fitering.
From here the water is conveyed in pipe
to a reservoir lower down, which will call
high level service reservoir. Practically the
distribution commences here, at an elevation
of $50 feet The distance between grade
points is I,o2o feet approximately. Here we
have n grade Of 2.4o per cent. for that dis
tance, for which I5.inch pipe is also pro-
vided. From this reservoir, containing
69.4I4 U. S. gallons, the water is conveyed to
the Nuuanu Reservoir at an elevation Of
IoI 66-Ioo feet For this service, a I5-inch
pipe is also provided. This may be called a
low level service reservoir.
An auxiliary supply from the adjacent valley
is received here, which might be largely in
creased withou, affecting the local demand
for irrigation to any serious extent.
The Makiki Valley Is source OF supply,
and some feeble attempts have been made TO
utilize it by the construction OF a reservoir Of
small capacity; and redwood tiume was
added some two years since which, believe,
is now somewhat dilapidated. will not now
discuss the reasons why redwood ilume was
made, instead Of a small pipe line, which, at a
moderate advance on the cost of said flume,
would have made valuable and permanent
source Of supply.
The Manoa Valley, with its large available
supply, has not been utilized in any way.
That an abundant and available supply
Of pure drinking water existed under our very
feet was not suspected until about four years
since, when the first arlesian well was sunk.
Waikiki and parts Of Punahou, instead of re-
naming an almost desert waste, have bloomed
value Of real estate was rapid and considerable,
which was mainly due to artesian wells. The
government well at Waikiki, when completed,
was fine sight. Its flow was measured by
Messrs. Young and Herzog, and found to be
about million and quarter Of gallons per
day, notwithstanding the diameter Of the inlet
OF the leading pipe was only inches. Two
| such wells delivering at the same elevation
would give az millions of gallons per day.
Assuming the absence Of all the previously
enumerated sources of supply, amounting in
the aggregate to OF millions Of gallons per
day, there is still another source available
impounding and storage Of the rainfall, with
the further assumption that il would be neces-
sary to provide for storage of ISo days
supply at the rate Of consumption equal 10 the
quantity furnished by the permanent Paki
Auwai Tor I,93S,SI6 gallons per day, or
As 4o-Ioo gallons per head for population Of
4o,ooo) In that case it would require a
storage capacity Of $40, ,aoI, 500 gallons anil,
owing to the slope Of the profile and limited
high dam would be reduifsaI" BAILEY, very
earth or masonry. This dam, thrown across
the valley at suitable point, would impound
OF dam up the required volume Of water, the
surplus escaping by overflow wier or waste
outlet.
The history Of earthen dams particularly is
replete with disaster and loss Of human
liie, consequent upon their failure and such
failures have occurred, even though they were
constructed under the direction and supervision
Of the best engineering talent. A long lis, Of
those failures is At hand. A dam, say So feet
high thrown ACROSS the Nuuanu valley at any
point and falling through any cause. as fresh.
e''' unequal subsidence or earthquakes. would
'n'olve catastrophe, the extent Of which il
does not need much intelligence to perceive
Owing to the unstrati6ed character Of the