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San Francisco (Calif.). Board of Supervisors.

The municipal employee (Volume v.3 (Jan. - Sept. 1929)) online

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18. The Golden Gate Bridge will



Success to

GOLDEN GATE BRIDGE BONDS

A Friend



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special City Purchasing Department's
discounts to all municipal employes, and
also free installation services, handsome
free tire covers, and courteous and effi-
cient attention.



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3if



THE MUNICIPAL RECORD



Octobe



give four years of emplo3'ment to
San Francisco labor and will meafi
the spending of approximately
$735,000 a year in San Francisco for
that period. After the period of
construction there will be continu-
ous employment for operation and
upkeep, purchase of light and main-
tenance.

19. San Francisco lacks play-
grounds and open air diversion. The
Golden Gate Bridge supplies that
lack and gives to San Francisco the
same advantages in that respect that
Los Angeles enjoys.

20. The Golden Gate Bridge, with
its easy and quick trips to the city,
increases tthe radius of the city's
markets and mercantile establish-
ments. There will be more buying
in San Francisco and less across the
bay.



21. Both due to the through traf-
fic on the bridge and the increased
density of population produced by
every great bridge, there will be a
general rise of prosperity in San
Francisco.

22. The bridge will aid San Fran-
cisco harbor in providing direct
truck access and outlets to the San
Francisco piers from both sides of
the bay for the evading and un-
loading of cargo.

23. The bridge will facilitate the
direct truck delivery of milk and
farm products to San Francisco and
thus reduce the cost of thSse prod-
ucts to the San Francisco consumer.
Similarly direct truck delivery of
San Francisco products will be fa-
cilitated.

24. The Golden Gate Bridge will



increase night life in San Francisco
and increase patronage of theatres
and concerts, because of the ease
and comfort of the return trip.

25. The Golden Gate Bridge will
increase the use of automobiles in
San Francisco because of convenient
and attractive places to go.

26. The Golden Gate Bridge will
permit the development of a belt
line service between San Francisco
and the trans-bay district.

27. The above outlines the effect
of the Golden Gate Bridge upon San
Francisco. It evidences that the di-
rect and indirect returns of the
bridge to San Francisco are im-
measurably great, that it is San
Francisco's prime need and that the
building of the Golden Gate Bridge
will at the same time build Greater
San Francisco.



DRIVING HETCH HETCHY

AQUEDUCT TUNNEL

THROUGH THE COAST

RANGE MOUNTAINS

By L. B. Cheminant, Assistant City Engineer



kNE of the most interesting and
difficult operations of the moun-
tain water supply project is the con-
struction of the tunnel which will
conduct the Hetch Hetchy water
from the San Joaauin Valley to the
valley of San Francisco Bay.

Begins at Tesla Portal

The tunnel begins at Tesla Portal
at the base of the foothills, seven
miles south of Tracy, runs in a gen-
eral westerly and southwesterly
direction for 25.1 miles and emerges
to daylight at Alameda East Portal
in Sunol Valley about two miles
south of the well known Water
Temple. Pipe 0.6 mile in length will
be laid across this valley to Alameda
West Portal, the beginning of a sec-
ond unit of tunnel, 3.6 miles long,
which ends at Irvington Portal, near
the historic old Mission San Jose.



The twenty-five-mile single tun-
nel is the longest tunnel ever at-
tempted by man, and overcoming of
the many difficulties encountered in
its construction is reflecting great
credit on the men engaged on the
work. A great many of these men
are seasoned veterans who so suc-
cessfully drove the nineteen-mile
and seventeen-mile tunnels between
Hetch Hetchy and the San Joaquin
Valley.

Tunnel Location

The tunnel location is practically
along the line originally selected in
1912 by John R. Freeman, assisted
by Dr. J. C. Branner, an eminent
geologist, now deceased, who for
many years was head of the Geo-
logical Department and for some
time acting president of Stanford
University. Before finally locating
the tunnel line, the city engineer
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made further studies by means of
diamond drill borings and by -a de-
tailed geological survey by H. J.
Packard. As a result of these
studies, the location of the line near
Corral Hollow Creek was shifted
southerly to avoid, so far as pos-
sible, the Cretaceous formations
which had caused much trouble in
the old Tesla coal mines. This shift-
ing to the south had a practical
limit, as the further the shift the
deeper must be sunk the shafts
through which the tunnel operations
are being carried on.

Shafts Were Sunk

The. shafts were sunk to facilitate
the tunnel operations by providing
more points at which the work could
be carried on. In the twenty-five-
mile tunnel there are five shafts,
from each of which tunnel is being



October



THE MUNICIPAL RECORD



319



driven both east and west. Shafts
are located in canyons, so therefore
they are spaced unevenly, the great-
est distance between them being 5.2
miles from Mitchell Shaft to Mocho
shaft. The projection of the survey
lines from the surface, down the
shafts and through the tunnels re-
quires the most careful and precise
work that the surveyor is called
upon to do.

Sinking Shafts Began

Sinking of the shafts began in
1927 after an unwarranted deay of
six months, which was occasioned
by failure of the Suoervisors to ap-
prove the city engineer's plans for
this work. As fast. then, as funds
were available, construction camps
were opened, machinery installed,
and work begun. On June 3J. 1928,
the end of the fiscal year 1927-28.
the shafts were approaching comple-
tion, 2245 feet having been sunk to
that date. During the next fiscal
year, twelve of the fourteen tunnel
faces had been opened up and 4.1
miles of tunnel driven. During the
fiscal year 1929-30, the remaining
two tunnel faces were opened and
nine miles of tunnel were driven. At
present, fourteen and one-half miles
have been driven. Between Tesla
and Thomas, and between Ind.an
and Alameda creeks, not much more




than 3000 feet of tunnel yet remains,
before concrete lining may be placed.
In June, 1930, a record orogress
of one mile of tunnel driving was
made. Organization had been per-
fected and operations were being
carried on with the precision of
clockwork.

It was alwavs anticipated that the
driving of this tunnel was a difificult
undertaking. The ground penetrated
is very unstable and in many places
has a tendency to swell. In ordi-




COAST RANGE TUNNELS. HETCH HETCHV WATER SUPPLY PROJECT
Upper left: Warning signs at shaft. Upper right: Bloiier, 10,000 cubic feet per
minute capacity. Can be operated either to blovi or exhaust. Lotrer left: Coast
range tunnel shelving effects of sivelling ground in crushing heavy timbers. Loiver
right: Coast range tunnel, placing gunite concrete in lO' 6" tunnel to prevent
crushing of timbers by s'ivetling ground.



nary ground, it is common to place
timbers of 8x8-inch pine at five-
foot centers. In this tunnel it has
often been necessary to place the
timbers at three-foot centers or
closer and to increase the size to
twelve by sixteen inches. In places
the ground has run so that it is nec-
essary to "breast-board" or place
tight lagging so that the ground will
not run into and entirely block the
tunnel. These conditions have been
met by lining the tunnel with gunite
concrete as soon as possible after
opening up the ground. At present,
more than one mile of such lining
has been placed.

Occasionally the bore penetrates
seams in the rock which carry large
quantities of water under heavy
pressure. In one case a water flow
of 2500 gallons per minute was en-
countered, enough to supply a city
of 40.000 inhabitants. Such flow's
are generally cut ofT by forcing ce-
ment grout, by means of a high pres-
sure air gun, into the seams, thus
filling them with a sort of concrete
and allowing the work to proceed.

Most Serious Difficulty

The most serious difficulty was
the occasional occurrence in some
places of methane gas, a combina-
tion of carbon and hydrogen which
constitutes 80 per cent of the natural
gas that is used for cooking and
heating. This gas, when mixed with
air in certain proportions, (from
5 to 15 per cent) is highly explosive.
In the tunnels where methane was
detected, elaborate precautions were
taken to prevent accidents, but nev-
ertheless, on July 17, 1930, an explo-
sion in the east heading from Mitch-
ell shaft took the lives of several
men. For some time prior to this,



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320



THE MUNICIPAL RECORD



October



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Concrete Road Paving

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821 Folsom Street

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SAN FRANCISCO, CALIFORNIA



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permitting resumption of tunnel

driving



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SAN FRANCISCO OAKLAND

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October



THE MUNICIPAL RECORD



321




Types of Safety Appliances

the city engineer had been in con-
sultation with the state engineers on
safety and had been installing nu-
merous devices and methods which
they had recommended. The coro-
ner's jury decided that the accident
was caused by a broken safety lamp.
In the pockets of two of the victims
were found smoking materials, al-
though the carrying of such into the
tunnel was absolutely forbidden and
was punishable by immediate dis-
charge from the city's service.

After the Accident

Immediately after the accident,
the newspaper "safety engineers"'
and other self-constituted experts,
began an extensive publicity cam-
paign. The supervisors directed the
city engineer to comply with all
safety orders. Consequently, work
was shut down in nine of the four-
teen headings, hundreds of men were
laid off, electric wiring, machinery,
etc., were removed from the tunnels,
horses and mules temporarily sup-
planted the electric locomotives, and
general disorganization of the work
followed.

In the meantime, a commission of
representative citizens appointed by
Governor Young to formulate plans
to prevent similar accidents, re-
ported that the ratio of fatal acci-
dents in the Hetch Hetchv tunnels
was lower than the rate for Califor-
nia, or that for the United States.



This fact was not printed in the
newspapers that had pursued a pol-
icy of exaggeration.

Work has now been resumed in
all headings. The city is working in
close cooperation with the state and
Federal l)ureaus. All safetv matters
are handled by a safety committee
of three, one being an assistant en-
gineer on the Hetch Hetchy project,
one from the State Industrial Acci-
dent Commission, and one from the
United States Bureau of Mines.

"Permissible locomotives" were
purchased and are now being put
into service. These locomotives are
very similar to the ones previously
used, except for complete enclosure
of all parts that might either nor-
mally or accidentally produce a
spark. All such parts are equipped
with locks that can be opened only
by an authorized oerson in a special
room provided for this purpose near
the shaft. This room for charging
the storage batteries of the locomo-
tives is lined with concrete and spe-
cial provision is made to keep the
air in it fresh and free from gas.
There are twenty-seven of these new
locomotives, fifteen of them being of
five tons and twelve of four tons.
The records show no gas explosion
to have ever been caused in the
Hetch Hetchy tunnels by the older
non-permissible locomotives.

One of the oldest safeguards in
coal mines or other mines showing
gas has been the flame safety lamp.
This is a device with a font "holding
gasoline or some other inflammable
liquid, and a wick adjusted to burn
with a very small flame. This flame
is seen through a glass globe and is
prevented from free access to the
other air by a wire screen. If an
inflammable gas is present in the
air, the flame increases in size, thus
announcing the condition to the
shift boss, who must then remove
the men from the workings until the
air becomes satisfactory. The flame
safety lamps used are magnetically
locked so that they can be opened
only by an authorized person in a
proper place. One of the rules is
that safetv lamps must not be left
unattended in the tunnel.

Another device used for the de-
tection of inflammable gas is carried
by the fire boss. This detector has
a filament which is electrically
heated. In the presence of inflam-
mable gas the filament becomes fur-
ther heated by the combustion of
the gas and the amount of gas is
indicated by the reading of a volt-
meter. The fire bosses constantly
patrol the tunnels and test the air,
keeping a record of time, location,
amount of gas if any, etc., etc. It is
his duty to advise the boss of con-
A Million Majority for Ralph



ditions, and if necessary, to instruct
him to take the men out of the tun-
nel. He must also test the air before
and after blasting.

The ca]j lamjjs, which constitute
the sole illumination in the tunnels
where gas mav be found, consist of
two cells of Edison storan'e battery
in a metal container, strapped to the
back bv a leather Ijelt and with




Flame Safely Lamp

reinforced lamp cord extending to a
headpiece which is clipped to the
man's cap. The headpiece has a dou-
ble filament lamp, one to burn ten
hours and one to burn twenty hours.
The lamp socket and fastening are
so arranged that if the headpiece or
glass be broken, the lamp bulb will
pop out and break the circuit. The
battery cover is locked and can be
opened only by an authorized per-
son at a proper place. Batteries are
taken to the surface every shift to
be cleaned and charged. The use of
these small lamps instead of the for-
mer electric lights has resulted in a
large increase of bruised and
smashed hands and feet, as the
worker is put to more or less dis-
advantage by lack of powerful illu-
mination.

Fresh air is provided by blowers,
operated by electric motors, with



3^^



THE MUNICIPAL RECORD



October



capacity of 10,000 cubic feet per
minute.

Pumps used in the tunnels are
driven by compressed air but at the
shafts, where the air is fresh, elec-
tric equipment is operated.

No open lights, cigarette lighters,
matches or smok.ng materia. s are
permitted underground. Notices to
this effect are posted at the surface
and the men are searched at irreg-
ular intervals to see that the rule is
observed.

Ample fire protection is afforded



at all shaft head frames by high
pressure water supply and many
hydrants.

Man cages are used in the shafts
for hoisting and lowering men. All
cages and skips are equipped with
safety devices as satisfactory as
those in the most modern office
building.

Elaborate provisions have been
made for handling emergencies. At
Livermore, mine rescue equipment
is kept available at a moment's no-
tice at an)' time of day or night. The



city maintains a hospital with doc-
tor and ambulance service always
ready. Mine rescue squads of over
100 specially picked men are trained
for emergencies.

The partial shutdown of the work
in the tunnels during the period of
waiting for permissible equipment
together with the cost of equipment
and the loss of efficiency is esti-
mated to have cost the Hetch
Hetchy work about $1,000,000 and
to have resulted in six month's de-
lay in completion of the tunnel,
which is now set for the year 1933.




SAN FRANCISCO'S

PROPOSED

AIRPORT RANKS

HIGHEST



•HSlif*-



By L. J, Archer

Assistant City Engineer



E. JACK SPAULDING
Chairman, Airport Committee



WORLD acclaimed for harbor
facilities, San Francisco is
concentrating attention on a com-
parable airport. Favorable action
on a $4,000,000 bond issue will
bring to the San Francisco Bay re-
gion a second Golden Gate — a
gateway to the ships of the air.

"The time has come," declares
President Hoover, "when there
should be at least one airport to
every community. The establish-
ment of such airports must be the
result of the initiative of the com-
munities themselves." In San Fran-
cisco the need is great. Experience
has shown that motorists are en-
couraged to travel where good
highways lead them, train and
steamer tourists where service in-



vites, and air travelers where air-
ports offer safety and adequacy.

Selection of Site

Few cities have made such com-
plete investigation for an airport
site as has San Francisco. Twenty-
odd sites have been advocated and
their merits weighed. Four sites
withstood the initial process of
elimination; a meteorological diag-
nosis extending over a period of one
year eliminated three of these, leav-
ing Mills Field supreme. It is this
site that it is proposed to develop
into a Greater San Francisco Mu-
nicipal Airport.

The airfield lies on the Bayshore
Highway, thirteen miles south of
the central part of San Francisco,

Let's Make It Ralph by a Million



twenty minutes by motor over a
125-foot-wide highway, and is sur-
rounded by the city limits of South
San Francisco, San Bruno and
Millbrae.

Establishment of location inaug-
urated proposals for land acquire-
ment, which resulted in a purchase
agreement to obtain an estate of
1114 acres for $1,050,000, three hun-
dred acres of which are tidelands.
The city purchased 112 acres of the
above from general fund money.
Bond issue money will purchase
the remaining acreage, together
with 1080 acres additional tideland
acreage necessary for required area
and reclamation borrow material.

Airport control and administra-
tion are vested in the Airport Com-



October



THE MUNICIPAL RECORD



323



iiiittce of the Board ot Siiin-rvisors,
Supervisor Jack Spaulding. chair-
man. Construction and develop-
ment plans are being promulgated
in the office of M. M. O'Shaugh-
ncssy, City Engineer of the City
and County of San Francisco.

Reclamation

Requirements necessitate the con-
struction of 11,000 lineal feet of
levee to bound the bay side. Pro-
tection from wave action will be ac-
complished by placing heavy riprap
on the shore slope of the levee
within the vicinity where such ac-
tion will exist, using lighter rock
to form a blanket, against the levee
side and to provide a water seal.

Hydraulic fill to an average
height of thirteen feet will be placed
upon the tidelands, and five feet
upon the existing used field. The
surface will be graded from a high
point at the central runway inter-
section, which will provide partial
drainage and decelerating force
upon a landing plane, and acceler-
ating force upon a taking-off plane.
(Note paragraph upon Operation,
following.)

Runways

The necessity of definite opera-
tion, control, practicability and
economy dictate the use of hard
surface runways. This type of sur-
face advantageously provides a sta-
ble surface under all weather con-
ditions, affords low tractive resist-
ance, obliges comparatively little
maintenance, and encourages in-
creased traffic. It is obviously im-
practical to "hardsurface" the en-
tire field.

As the movement of an airplane






BERKELEY




Fiff. 1. I'icinity Map



in approaching and landing at an
airport is almost entirely governed
by the wind direction and the corre-
sponding runway paralleling the
wind direction, particular attention
to runway orientation is essential.
The \\'ind Rose, shown in Figure
3, indicates the percentage results
of a continuous anemograph record
directed by the weather bureau
over a period of nearly three years
at the airport. The direction of the
prevailing wind Avas deduced from
these records and a basic runway
laid parallel to this wind. Addi-
tional runways were oriented to




Fig. 2. Existing Field, San Francisco Municipal Airport (Mills Field)



enable a plane to take off within
221/2 degrees of the wind direction
under all circumstances.

Actual Taking-off

Actual taking-off and landing dis-
tances are not large for the usual
conditions of operation. The dis-
tance traveled before the wheels
leave the ground is, in some in-
stances, when running into the
wind, as short as 150 feet. The dis-
tance required to stop after the
wheels first touch the ground is, as
a rule, materially longer as com-
pared to the taking-off distance,
where sole reliance for deceleration
is placed on the frictional resistance
between pavement and tail skid.
The runway should be of a suffi-
cient length to allow an airplane to
land dead ahead should engine fail-
ure require so before the airplane
has gained sufficient altitude to
make a turn and land on the field.
The Department of Commerce re-
quired at least 2500 lineal feet of
effective length to applicants for
highest rating.

Given Ideal Conditions

Given ideal conditions, an air-
plane can be landed on a very nar-
row runway, but under normal op-
erating conditions, where cross
winds may prevail, tires may flat-
ten, or brakes bind, 130 feet should
be the minimum. Runways as shown
on the fully developed plan (Fig.
5) are 400 feet wide.

Surface treatments vary from
natural soil to concrete pavements.



A Million Majority for Ralph



324



THE MUNICIPAL RECORD



Oaober



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135 TEHAMA STREET

SAN FRANCISCO

KEARNY 5441



Manufacturers of

Metal Furniture, Lockers, Counters, etc.

Recent installations for City of San Francisco:

Steel Counter Top — Municipal Courts, City Hall
(longest steel counter in San Francisco.)

Bedside Tables — Laguna Honda Home.

Document Files — Auditor's Office, City Hall.



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SUCCESS TO THE AIRPORT
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PLUMBING AND HEATING SUPPLIES



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SAN FRANCISCO

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OAKLAND



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Wishing Success to the

San Francisco Airport Bonds



JOS. P. QUINLAN

MAYOR OF SOUTH SAN FRANCISCO



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Phones: S. M. 541 or S. M. 542

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Branch Yard: 1000 Broadway, BURLINGAME
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October



THE MUNICIPAL RECORD



325



Adaptability for the various sur-
faces finds advocates for turf, water-
bound and claybound macadams,
cinder, slag, wood block, bitumen,
brick and concrete.

Well-Kept Turf

A well-kept turf rinds high favor
among the pilots in the summer
months, but is apt to be disappoint-
ing in winter when standing water
renders the surface unstable. Irri-
gation, where required, may make
turf maintenance costs excessive or
even prohibitive. Asphaltic con-
crete provides in some degree the



Online LibrarySan Francisco (Calif.). Board of SupervisorsThe municipal employee (Volume v.3 (Jan. - Sept. 1929)) → online text (page 75 of 84)