The morning call., 1893-07-18
CITY SEWERAGE.
Preliminary Report of the
Engineers.
WHAT THEY PROPOSE TO DO.
Marsden Manson and c. II. Grunsky
Send VOiuminous Commune
cation to the Supervisors.

the engineers appointed TO devise a sewage
system for San Francisco, filed a prelimi.
nary report with the Board of Supervisor:
yesterday afternoon. 1t is a volaminous
document containing over $1,000 words
The drainage history of the city is re-
viewed i'll detail. The various defects in
the system are enumerated at length and
the recommendation for sewage changes
made by successive municipal officers are
appended.
The report begins with description OF
the geographical features Of the city,
San Francisco's area, including the lands
already reclaimed and TO be reclaimed, Is
3O,6S0 acres, about As square miles, the
area already built upNa covering oOoo
acres There are eleven natural water
sheds for whose drainage provision is to
be made. as follows: Visitacion Valley.
900 acres; Bay View, 1920; lslals Creek,
800; Precita Greek. 1850; Mission Bay,
$3.50; Yer ba Buena, 430; y orth Beach, so !;
asherwoman's B y, 1880; Preside. $50 !
Lobos Greek. 2120; Ocean Beach. $3.50;
Laguna de la Merced $3.50.
The problems of drainage for these sew
eral districts are distinct for each. but can
to a certain degree be combined. In the
report each of these districts is described
in detail, showing their present conditions
and facilities for drainage
The eng neers then discussed the dis
pasal OF the sewage. The original points
of Outfall, formed by the hills and ridges,
have been and are adhered TO, until in
creased population causes an aceumula-
tion OF filth in the vicinity of the points of
delivery. The city is gradually being en-
cOmpaSSed by margin Of filth deposits.
There are no large areas suitable for sew
age irrigation within easy reach, on which
10 utiiiZo its sewage.
They reach the conclusion that eventually
the volume of sewage Will be too great to
be delivered to the bay in continuous flow
at one or more selected points, and the en-
tire volume will be concentrated for dis
charge at the most suitable points into the
ebb flow. The permanent work now pro-
posed should be so planned that this ulti-
mate result can be obtained without re-
constructing the main lines of the sewer.
now necessary.
The specifications require that pipe sew
ers shall have openings twenty-five feet
apart sufficiently large to receive 6-inch
pipe. Sewers have been constructed within
year with less than One-tenth of the re-
quiGed number of Y's for house connec-
tons Others have been accepted as prop
eriy constructed although the openings re-
quired were put upon alternate sides Of the
sewer, making those upOn either side fifty
feet apart. In no case has q record Of the
position OF the Y's been preserved. House
connections have frequently been made by
breaking through the sides Of the sewers
whenever convenient. ManholeS have
been constructed without steps, although
steps formed Of half-inch iron are required
by the specifications.
The detailed specifications required for
seweT-conStructiOn are given, and the law
relating to such public work explained in
detail A number OF instances of work
improperly done are cited, some of the de-
tective results affecting the main sewers.
The necessity for local notifications in
sewers for the improvement in sanitary
conditions Is next discussed in the report
A-hich shows that evils out of sight, but
creating nuisances of the worst kind exist
INA parts OF the city. These defects in
ciuCe excessive size, improper gradients.
inferior material and careless workman
ship. The earliest possible provision
should be made for abating those which
most seriously menace the public health
The practice of constructing sewers in
detached sections is condemned, as also
of building large brick sewers in street
crossings. Illustrations are given of this
bad practice of constructing large brick
sewers where very small pipe sewers
would have served the purpose. The con-
struCtion Of a vast number of useless
catch basins is severely criticized as serV-
ing no purpose but to yield profit to con-
tractors and contaminate the healthful-
ness Of the city. The useless catch basins
have cost the prOperty-owners S12. .500
The engineers believe that no incoDve-
nience would result if they were further
apart than one at the foot of the slope of
each block.
Many storm water iDlets permit the es-
cape of sewer gas. The engineers say
that these inIets are unreliable even when
IN good condition, and are frequently out
n dnr 'hnx- lxv r..I1
the outlet Of silt. This can be kept out only
by frequent and thorough street sweeping.
1t Will be economical to intercept this ma
terlal before it enters the sewers, instead
CT removing it later by more expensive
methods. To this end it is suggested that
hereafter all cObbestone or broken rock
gutterwayS on macadamized streets should
be thoroughly grouted with cement mortar.
a compilation of official street grades is
appended to the report. incidental to the
making OF correct Typographical map of
the city. The repor. says on 300 miles OF
streets grades have not yet been officially
esta blished. The grades should be changed
in many places before expensive local i'm
provemeDts are made, that will render
such changes difficult 1t is suggested that
a point near the City Hall be selected. its
elevation determined, and the point made
the basis for elevations above city base.
The engineers argue against c0ntinu-
ance OF the present system. Ihey say 1t mas
not only led TO the acceptance of much de-
fective work, but also its maintenance is
costing the city large sums annually. The
records Of breaks in sewers and the under
mining of street surface are cited in illus
traton. In nearly every instance the
damage to sewer and street was caused by
an inflow Of water into the sewer through
open joints in. the pipe sewer or in the
brickwork. Water thus carried with IL
sand and soil, undermining the street pave
ment and causing general collapse.
There is radical defect in our system
of sewerage" proceeds tie report ''lt
must be corrected some time, and the
longer this action is deferred the more
difficult will be its removal. The SOUTH
western portion of the city is more in need
of'this reform than any other. The entire
grade OF that portion of the city will have
to be raised along for several blocks from
the water front"
The plan which was suggested by Mayor
SelbY is approved. 1t is to construct a
reservoir on top of Russian Hill or some
eminence near the bay, in order that, with
suita Bile machinery, the reservoir may be
filled with salt water. The reservoir is to
be connected with the main sewers by
means of aQueducts. so that they may be
flushed or washed out as often as occasion
may require tn keep them from filling up
Or hacc t,oin fn nj off ie