The Providence news. (Providence [R.I.]) 1891-1906, 1894-07-24
Filtration.
A Letter from the City Engin-
eer to the Mayor.

TIL following letter relative to the nj
| tration question, which Mayor Olney has
today received from City Engineer Shedd,
is self-expl snatory:
Hon. Frank r. Olney. Mayor. ETC.;
Dear Sir-I am told that stories are persist
entity circulated hers, by those who seem 10
have a personal interest In disparaging $40"
filtration, 20 the effect that slow filtration has
proved 10 be "A failure at Poughkeepsie. n. Y.
/ nave taken pains 20 ascertain the facts
about this and will repeat a few OF them 10
you.
Two flter-beds of the ordinary construction
for slow filtration were built there In 1917
under the w~ell-known engineer, James l..
Kirkwood. and they have, except for n por-
ton OF the earlier years, been In successful
operation ever since. or for about twenty-five
years. The water is pumped TO the beds
through a receiving basin and the filtered
water passes TO a clear we'll and thence TO the
suction pipe of the main pump.
So far as l can learn, the only ground Tor
dissatisfaction with the operation of these
beds results from their being over-taxed, the
water being run through them at about the
rate of seven inches vertical depth in an hour
or about double the approved rate. TIL pro-
posed rate for the city of Providence Is three
inches per hour.
The superintending engineer has said:
"The constant operation of these beds, at all
seasons. is an absolute necessity in order 10
render the water OF the HUDSON river at
this point 1T for domestic use. and
no effort is spared to maintain them
in excellent working condition. And
again In reporting on the disease germs In the
river, he says: "Our filter beds constitute our
greatest safe guard, Therefore, no effort or
reasonable expense should be spared TO main
tain them in the highest state of efficiency"
Professor Drown of Boston in reporting
upon water under date of June ~, 1893, said +:
There Is no good reason why the Hudson
river should not continue 10 be used as a
source of supply for Poughkeepsie If the fl
ters are kept in a high degree of efficiency.
Az present they are overtaxed they should
have twice their present area To bring down
the rate OF filtration 20 the standard of
good practice" After giving an account of
| analysis he says ''The water was clear.
nearly c~olorless, and free from turbidity and
sediment. IL was In striking contrast to the
river water applied TO the filters. The average
of the analysis of the six samples showed a
removal of thirty-eight per cent. OF the al
buminoid ammonia, and twenty-nine per
cent of the oxygen consumed. and ninety
seven per cent. OF the free ammonia" In
conclusion he says: This citizens of Pough-
keepsie are to be congratulated on the good
work the present filters are the puri-
fication of the river waite , oi. 1 consider IL
essential to perfect security that the hltering
area should DO increased in order that the
rate OF filtration should be slower and more
perfectly under control"
uIt may be that the basis for the stories so
industriously circulated about the natural
filter has relation really TO n mechanical
filter which the city has been experimenting
with for two years or so. In regard
TO this the superintendent writes TO
me that in mechanical design and con-
struction IL is a complete failure. TO the
SUCCESS or rhe PROCESS with our wutcr, there
has not been sufficient trial To determine. /
may say, however, that Ihave seen no indi-
cations OF success as yet. j see no hope for us
but in the slow filtration PROCESS.
Yours respectfully.
J. HERBERT SHEDD. City Engineer.
Badness Is either hereditary or caused by
sickness, mental exhaustion, wearing tight
fitting hats. and by oyer-work and trouble,