The San Francisco call., 1910-04-23
Big TUBE Will
SOON BE BUILT
Bore viii Be One Mile Long and
Serve Is Square Miles of
San Francisco County

The plans are nearly completed for
the city's sl.OOO.0o tunnel through the
solid cliffs between Golden Gate park
and the ocean that will serve as the
drainage outlet for more than one
fourth of the entire area OF the city
and county of San Francisco. The
sunset district, Parkside, Oceanside,
Ingleside and Richmond district. for
a score Of blocks back from the ocean,
are included in a vast drainage sec
tion. the largest individual subdivision
ia the entire city, that viii be perma-
nently benefited
The Sunset area proper extends from
First avenue, which is eastward of the
affiliated colleges, to the great high
way that fronts the ocean beach. and
then runs through the Sutro forests
and into Ingleside, and has like width
along the ocean beach and through
the entire east and west and north and
south extent of scores Of blocks that
run fro mthe Golden Gate park front
age TO Parkside. and are hemmed in
by the ocean and First avenue.
The Richmond drainage area to be
served extends from d street or Full
ton. TO the northerly edge OF the land
on the ocean and from about Twenty
seventh avenue west There are about
50 square miles Of land surface in the
city and county OF San Francisco. The
drainage region, roughly indicated
herein, comprises Is square miles.
CALLED MILE ROCK TUNNEL
The bore or tunnel will be known as
the Mile Rock tunnel. 1t viii begin
at G street and viii run through the
cliffs and about ] 900 feet off Mile rock,
and viii there discharge the concen-
trated sewage into the ocean. AS de-
scribed by the board OF works the Mile
Rock tunnel will be a great example
OF constructive work. IN the first place
il will be more than one mile long and
il viii be driven through solid rock for
that entire distance 1t VIII be 10 teet
wide and feet high. II viii slant
downward from the beginning of its.
course with suficient grade TO give the
sewage good headway on its voyage
toward the ocean.
Being cut through solid cliffs the
tunnel will probably last forever. so
that the large initial cost of construc-
tion viii not be repeated. as might be
possible We're the structure of brick.
To bring the sewage from Sunset,
Ingleside, Parkside and Oceanside a
system Of large sewers has been
planned and is under construction. II
will find a junction al Forty-flfth ave-
nue. in Sunset The sewers viii run
under the park and out 10 the shore
end Of the Mile Rock tunnel which VIII
be at Forty ghth avenue and { street.
In pursuance of this engineering plan
a great outlet sewer is in construction
in II street. which in connection with
the Improvement of II street TO the
ocean from Twentieth avenue, will prove
70 be Of almost inestimable benefit 10
sunset and its subdivisions, Ingleside,
Parkside and Oceanside-
The plans for the Mile Rock tunnel
will be ready TO submit for bids Tor
construction soon. Possibly work VIII
begin on the tunnel during the present
summer. The figure OF 81 600. 600 used
herein represents the cost of the tun-
mel alone, and may be somewhat out OF
the way. but the estimate of Sl,OOo,oOo
is spproximately correct. When the
construction contract is awarded time
limit for the completion Of the work
viii be one OF the conditions attending
the award It is. Of course, desirable
that the tunnel shall be ready to use
as soon as possible. The territory that
il will serve is building up rapidly and
the demand for early action is corre-
spondingly strong. When the Mile
Rock tunnel is operative it viii settle
sanitary conditions satisfactorily Tor
one-fourth Of the city and county for
all time
LARGEST CITY UNDERTAKING
Ar the OceanWard terminal OF the
tunnel there is always a strong TIDAL
movement. which is accompanied dur
ing certain months of the year by an
irresistible freshet current that Will
hurry the sewage far out to sea.
During construction the Mile Rock
tunnel will be a center of interest on
account Of the size of the work, which
will be, by far, the largest individual
municipal sewerage enterprise upon
which the city and county has ever en-
barkyd. and also because Of the busi-
ness interests that il will promote.
Value will be added TO each and every
one Of thousands of building lots in the
Sunset and Richmond districts. In this
aspect of the case the real estate own
ers and the brokers who are selling
properties in what are known as the
outside lands" districts are Immediately
concerned.
The Mile Rock tunnel takes on an
other phase of interest because it is
generally supposed that the exposition
will be situated somewhere in the west
ern portion Of the city. In this view of
the case the great sewer system, of
which the Mile Rock tunnel will be the
outlet will be sufficient to care for the
needs of the exposition. incidentally il
is estimated that the sewers and street
Improvements in progress and planned
for the Sunset and Richmond districts
will add in value much more than the
money they will cost.