Los Angeles herald., 1906-12-25


bic for reasons both Of economy and
durability
There also entered into this question
the consideration Of the possibility of
the steel market being able to afford
in a reasonable time such n large order
as these siphons would involve. In
deed, 1t may be said that cutting the
distance piped down to the lowest pos
sible distance still leaves a tonnage
that may prove troublesome to supply
unless plenty of time is given the mills
to fll the order.
There Is an economic question in
volved which will no doubt appeal 10
your citizens that, with the execution
OF the steel In the siphons and the ma
chinery equipments, the entire cost of
building, both for material and labor.
VIII be distributed among your own
people, If the intention is carried out of
producing the cement required.
After a very careful study of all the
conditions In detail this board is of the
opinion that all Of these changes are
desirable and recommends that they be
made.
AS result of our studies, il has
been necessary to make new designs of
sections of the various types of aoue-
duct suited for the several localities to
correspond with the sleeper grade and
the more conservative factors allowed
for frictiona! resistance.
Reservoir Site
THE most important reservoir site
on the line Of the aqueduct is that
next between the intake, as IL affects
q means of direct equalization of the
flow of the main canal and the streams
gathered by the canal The reservoir
is situated on a summit in the valley.
from which the natural drainage is in
poth directions, north and south. II
mas length of IA miles. measured
along the thread of the valley. the
south dam being the larger of the two.
~ rect in maximum height with a top
length Of 300 feet. Materials in the
vicinity are favorable for the erection
OF safe substantial dams of earth at
both sites.
THE capacity of this reservoir at the
elevation of 1850 feet, as surveyed by
Mr.. Mulholland, is computed at 63, 7SO
acre-feet By building the dams ten
rect higher, this capacity may be in
creased to $3.50 acre-feet, a most val
liable increase in storage, although re-
quiring a diminution of the fall in the
main feeder canal by ten feet in 81
miles. The position of the canal is such
that 1t cannot be raised at the upper
end without sacrificing the flow at
Blackrock Springs.
Below Blackrock Springs we find
this change of gradient of the canal,
APPARENTLY involves no special difficulty,
and we recommend that this change
receive further consideration.
THE Long Valley reservoir, with a
dam 140 feet high, has a capacity of
100000 acre-feet, or $4,000, 600, 900 gall
Ions in round numbers, which is sew
eral times the largest existing reservoir
A Jttr 90 IL.
OF water measurements by the u, S.
geological survey for three years on
owens river, and a comparison with
longer records of stream flow on Kings
river, on the western slope of the
Sierras, indicates that when this reser-
voir is created, the equalization of
seasons of extremely large run-off,
with that of dry years, will effect q
saving of water which is now lost to
all useful purposes, amounting to
about so cubic feet per second, in ad-
dition to the water controlled by the
aqueduct, and owned or appropriated
by the city. This addition Is necessary
to the ultimate securing in years of
excessive drought of the full amount
of 400 second feet, for which the
aqueduct has been designed.
1.-THE board visited the Long Valley
dam site and examined the rock forma-
would have to be built. The river has
cut deep channel through volcanic
rock classed by geologists as tufa--a
rock which is much lighter in weight
than granite, but sufficiently strong to
be relied upon as a satisfactory
foundation for the construction of any
type of dam which may in future be
decided upon after more careful ex-
animation and study of all available
materials.
I'm the opinion of the board a stable
and safe dam can be built at this site
and the selection of the particular
type to be preferred is an economic
question which 1t is now premature to
discuss or attempt to decide.
"The Long Valley reservoir site,
which is chiefly embraced within the
limits of the lands purchased by the
city of Los Angeles, is admirably
flow, and the substantial increase of
the water supply of the aqueduct by
equalizing storage, and should be con-
sidered as an essential factor in the
general plan, to be developed as early
in the future as may be possible. For
the reason that this regulation of the
river is only required when the demand
has reached the maximum aqueduct
capacity and to provide against a
series OF ury years, IL mas not Deen IN
cluded in our estimates or considered
as an essential feature of the system
for immediate construction.
Estimates of Cost
1.-THE estimates of cost of the Los
Angeles aqueduct have been made up
of the following general subdivisions
whose leading characteristics have al
ready been described:
FIRST DIVISION,
Headworks on Owens river
to Haiwee upper dam, con-
sisting of 115, 400 of unlined
canal, from 700 to 500 sec.
feet capacity and 19S,500 feet
of masonry lined canal of
500 to 800 sec. feet capacity.
Total length $4,000 feet
(59.40 miles)
Estimated cost .........$ 3,712,100
Average cost per foot $11.S5
SECOND DIVISION,
Regulating reservoir with
capacity of 63,7S0 acre-feet
elev. 1850
Estimated cost of dams and
accessories, diversion of high
way around the reservoir,
but not including land dam .
ages is ,.........,........ 3l6,SOO
AUerapa pOst ner acre foot