Virginian-pilot. (Norfolk, Va.) 1898-1911, 1899-11-14
! CITY Alter \
The e'5 Bacteria logical ,estss Cond uct-3
eddy Df. IJetts Nj Cormick.
The teEsAscortaincd TO he A bovos
she the G1,uiyaranteo ss&dog by sion,rn,seS-..,
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j LittieS CROCK w aier. Is. e

-
Dr.. J. lett Met ormick was employed
by the Board OF lSW alter Comm issioners,
July "a tn last to make meteorological
tests Of the city water, in order that 1t
might be- accurately determined
whittier the New z ork FILTER Manu-
featuring Company, 4 to whom the CON
tract for the Inauguration of the filter
plant was given, had complied with it's
contract. Yesterday Dr. 4 Mccormick
made the, following report:
Norfolk, vi Nov. 10, 1899.
Honorable Board Of Water Commits
sloners, Norfolk, Vas:
Gentlemen, I'm compliance with your
instruct lions, began on October 10,
is99, the thirty-day guarantee test of
the filter plant constructed BY the New
York Filter Company for the Of
Norfolk. This test was to determines:
-. Inc reduction OF; color, which It
was guaranteed would be so per cent.
q The reduction of albuminoid am
monta In suspension, which 1t was
guaranteed would be 80 per cent.
3The reduction of bacteria, the
guarantee being that'if there were 1000
bacteria in the rawiwater to the cubic
centimetre, they would be reduced OF
per cent II there were less than 1000
bacteria per cubic centimetre In the
raw water there would tbe less than 100
per cent, cubic centimetre in the filter
ed wa ter. @
Inc samples of raw water were taken
at point about 20 feet from where the
water enters the reservoir for collec-
tion. The samples of the filtered Water
were taken from the flume at the north
end of the filter plant, where the water
howS into the brick reservoir to be
pumped to the city.
The average reduction in color Of the
filtered water was $3.50 per cent. The
only time that 1t fell below 90 per cent.
was on October 10th, when 1t registered
20 per cent. This was due to the sui
phate alumina being reduced to III
grains per gallon. should state here
that this plant was constructed to filter
the Lake Smith and Lake Lawson wa
ters, as 1t was the most sanguine expec-
tation of your department that it would
be two years before the Little Creek
water could be used. Upon the compile
ton of the filter plant the Little Creek
water was found by analysis to be
available, so the guarantee test was
made upon this water. The color of
the Little Creek water by the platinum-
cobalt standard is 81, the color OF the
Lake Smithi5water by the same stand
ard Is 80, and as tho quantity of sui
lportionali to the intensity Of color, we
have $500: :25a:xH.
In other words. If the test had been
made on Lake Smith water only q Of
O. grain per gallon would have been ne
cessary. I am Informed by your SUI
perintendent that the Lake Smith wa
ter was originally the color of the Lit
tie Creek water, and took two years to
attain Its present color. The same rule
should apply to the Little Creek water.
The method of determining albuminold
ammonia In suspension being arbitrary,
determined the total albuminoid am
monia in the raw and filtered waters
and found an average reduction OF 94.1
per cent, which is remarkably salts
factory. The average number OF bac-
terra per cubic centmetre in the raw
water was $50; in the filtered water 10,
giving reduction Of $3.50 per cent.
The cultures were made In gelatlne
bouillon of Is acidity. This medium.
according to the best authorities. gives
the maximum growth. The great in
crease In bacteria on November LIST and
Cd was due to heavy rain storm. The
raw water on those days was very
turbd. You Will observe:
]. That the guaranteed reduction In
color sof 80 per cent has been exceeded,
ne the average reduction was 93.6 per
cent. and this, in spite OF the fact that
the test was made on a water over
three times as highly colnred as the
one upon which the test was intended
to be made.
2. That the guaranteed reduction OF
albuminoid ammonia OF 90 per cent has
been exceeded, as the test shows OIL
per cent. reduction.
g. That there was an average OF 356
bacteria to the cubic centimetre in the
raw water; therefore the guarantee is
that there shall be less than 100 per