Evening star. [volume] (Washington, D.C.) 1854-1972, 1899-06-14
TO FILTER POTOMAC WATER
Experiments Now Being Conducted by Col.
Miller, in Charge of the Aqueduct.
Two Methods Are Being Tested and n
Report VIII BE Made
to Congress-.

colonel Miller. in charge of the Washing
ton aqueduct, has commenced the expert
ments authorized by the last Congress to
determine feasible system of filtration for
the general water supply of Washington.
The sum of $500 was appropriated to en-
able the chief of engineers, United States
army, to make experiments and report to
Congress upon this subject
General John NJ. Wilson, chief of engi-
neers, Immediately secured through the
agents of the State Department reports
upon filtration systems In Europe These
have been coming in for several months,
and will form part of the report made to
Congress next December. In the mean
time he caused the present experiments to
be started by Colonel Miller.
The experiments undertaken by Colonel
Miller are of practical character, and
expected to show the actual effect of the
several systems under local conditions of
application. Two systems are being tried
simultaneously, one by natural sand fiftra-
ton, the other mechanical filtration. Both
are being conducted in the rear of the
aqueduct office, at the western end of the
Pennsylvania avenue bridge across Rock
creek, and will continue until November or
December in order to test the water in all
kinds of weather.
Method of the Experiments.
rear of the office for the sand filtration ex-
pertinent. This is in effect miniature eX
ample of a sand filtering basin. The bot
tom of the tank is covered with layer of
rocks, above it are successive layers of peb
bles growing smaller, in size toward the
top, and above those layer of three feet
of sand The water filters through the
sand and rock, deposting the mud and bac-
terra in the various layers, and flows out at
the bottom clear as crystal
The river is exceedingly muddy at this
time, and the conditions are very favorable
for making filtration tests.
The experiment now is to filter the water
at rate which, if the scale were extended,
would be equivalent to 900 600 gallons an
acre a day. Later it will be increased TO
100000 gallons, and then 3,OiU,0OD in order
to determine the loss of head resulting
from the increased flow. This is a very
essential part of the experimeuu-to see
how much head is lost as upon 1t would
depend the question of whether the filtered
water under fixed conditions could be de-
livered to higher levels in the city.
When the cold weather comes on the tests
will have to be continued, because the
water in winter holds more particles in
suspension than in summer, and the flow
and rate of filtration will be affected.
If the natural sand filtration system
should be adopted by Congress, it would
result in the construction of fltering
basins capable of f1ltering sixty million gall
ions Oay, SO tnaC every gallOn or water
coming through the hydrants would be
clear and pure
While the water is being filtered, it is to
be tested for bacteria. The sand filters in
Europe. it is Claimed, remove 90 per cent
and over of the bacteria in the water. The
medical department of the army will make
tests frorG time to time for bacteria in
the water hltel ed by Col. Miller's tank.
Mechanical Filtration.
The mechanical system of filtration is
also In operation just below the sand filter
ing tank. 1t consists of large iron tank in
which the water is filtered by the aid of a
chemical injected into it. This system
works more rapidly than the other, and. it
is said includes all the patents granted up
to this time for mechanical filtration. This
will be tested equally with the other and
reports made upon the results OF each.
If this system were adopted it would call
for the construction of a series of great
iron tanks near the reservoir, housed in
and the building warmed in winter The
advocates of the mechanical filtration claim
that it is as destructive of bacteria as the
sand filtration system, and tests will be
made in this direction by the mechanical
department also.