The herald., 1897-07-20

knife carried by the observer for th'
purpose of probing the hardness of NOR
tar, brick and concrete was much cor.
roded. A weeks work in the acid-ladeI
| atmosphere of a chemical laborator!
would hardly have left it in worse con
dition.
But because these gases are present
apparently in large quantities, it is no
safe to conclude that they are the rea
corroding agent. They might very wei
be Only the products of the decomposi
ton and decomposition produced by th'
action of other substances on each othei
and on the cement and iron. 1t is not
impossible of belief that substances
might get into the sewage of this city
| from different sources which should, IL
strictness, not be admitted into sewer
1t Is conceivable that as long as Sucf
substances remain under the normal
conditions of sewer they may do little
harm and leave small traces of their
presence. But when they get under the
abnormal conditions of the outfall sew
er chemical reactions may set in, which
in themselves are destructive or pro-
duce other substances (solid gases, etc.),
which are the agents of decomposition.
Under the abnormal conditions of the
sewage in the 'outfall sewer I under
stand the long time during which the
sewage remains there, when retained for
irriga ton, the pressure under which 1t
then is, the concentrated state of 1t,
generally ard particularly of that por-
ton which does not rise in the hydrants,
and last, but not least, the total absence
Of To- of no
all gases to be bottled up, as it were, and
to be under higher pressure and greater
concentration than the gases in an or
binary ventilated sewer, hence chemi-
cally more active. The particularly pro-
nounced destruction of iron, plaster and
mortar in the two drop chambers-one
on section 5, the other on section Sap
pears to sustain this view of the matter
The fall and consequent churning OF
the whole mass of solids and fluids in
creases the energy Of the chemical re-
actions which produce the destructive
agents. which then, while in "statu ma
scepti," break up the constituent parts
of the cement and oxidize thu iron more
rapidly than they otherwise would.
To follow out this train of reasoning
would be the subject of special chemi-
cal investiga ton, producing analysis or
the sewage, the liberated gases, the de-
composed cement, etc. The immediate
practical necessity, however, is means
TO stay further ravages, which would
unavoidably end, sooner or later, in
disaster to this costly crown of the SAN
itary works of the city of Los Angeles.
While cannot absolutely know that the
following out of the following measures
will certainly arrest the further destruc-
ton of plaster, mortar and iron, yet dur
ing a former period, while conditions
similar to those to be recommended have
prevailed, no trace of this decomposing
and oxidfzing has ever been observed.
Mr.. Derby, superintendent of the outfali
sewer, indeed asserts that only few
months ago he showed a visiting engi-
neer over the works Of the outfall sewer;
the visitor, among other places, descend
ed into, and with special care and inter-
est examined the drop-chamber on sec
ton g. that neither of them then no
ticed the slightest indication of anything
unusual in the plastering; and that
most decisive of all-no trace of white
discoloration was on the visitors cloth
ing when he came up from the depths of
the chamber. But at present 1t is SIM
ply impossible to enter this chamber
without dislodging some of the decom-
posed plaster and having ones clothing
stained by it.
My recommendations are:
l. That the sewage be again diluted
as was formerly the case-by an ad-
mixture of about an equal quantity of
zanja water.
q That the unheard-of bottling up of
the noxious gases by air-tight closing
of structures be done away with by in
shutting good ventila ton at all of these
structures-not only as good ventila-
ton as the formerly used perforated
man-hole covers produced, but better
ventilation, by ventilating-pipes of not
less than twelve inches diameter, reach
ing sixteen feet above the surface of the
ground. Formerly, before the beginning
of the destruction of plaster, mortar and
iron, modera tely bad ventilation might
have been good enough. But, now that
actual destruction has set in at an IN
mistakably rapid pace, the best ventila-
ton obtainable is none too good.
The outfall sewer as designed and
built by me never contemplated the air.
tight closing of the manholes, and with
holding of the necessary water for flush
ing it, but on the contrary sufficient VEN
tilation was provided for and the zanja
system connected with it at several
points, so that the sewer was constantly
ventilated and could be flushed as often
as required. The testimony of the pres
ent and former superintendent amply
shows, that while this arrangement of
constant flushing and ventilation, even
if but moderate, was adhered to, every
thing went we'll and no deterioration of
any kind took place. On the contrary.
no sooner were my dispositions and ar
rangements disregarded and improved
upon" than a sudden and rapid destruc-
ton of the surfaces more Immediately
accessible to the deleterious influences OF
| chemical action takes place.
Councilman Toll, as chairman Of the
sewer committee, asked that the water
be turned into the sewer for flushing
purposes, in order to retard the deterio-
ration of the sewer.
Councilman Ashman thought that the
zanjeros department should be given
the credit for the water used in the
flushing of the sewer, and that the water
should be charged to the outfall sewer
fund.
Finally, on motion, the zanjero was
instructed to turn into the outfall sewer
two heads of water the same to be
rharpad IN the outfal1 SAWYER fund