Evening star., 1926-08-14

is expected to take the last step
toward the completion of Washing
tons modern water supply system by
making available the comparatively
small sum of S127,60O still needed.
This amount will put the finishing
touches on a project that will give
the National Capital a supply ample
for population of more than a mil
lion residents and remove all fear of
a water shortage for many years to
come.
Although the entire system will not
be complete and in service until
about June | next year, the new con-
duit from Great Falls TO Dalecarlia
Reservoir at the District line has been
In use for several months and has
improved the supply situation to
come extent this Summer.
Consumption on Increase.
In this connection it is interesting
to note from the records of the water
department that during the hot spell
of July consumption reached the
high mark Of S3,098,000 gallons on
July %. as against 100000 gal
Ions. which was the highest amount
used on any day in July, 1925, indi-
eating that the city is not getting the
enlarged supply system any too soon.
The new conduit, which is bringing
the water from Great Falls now while
the old one is being put in thorough
condition after having served as the
only source Of supply for half a CEN
tury, has a larger capacity than the
original conduit.
The full benefits of the new system
will not be available, however, until
completion about June l, 1927, Of the
1l1a T1f
and pumping station, located near the
Dalecarlia Reservoir. end on which
work Is progressing satisfactorily.
Must Use LydecI1er Tunnel.
Until the new filtration plant at
the western extremity of the District
is finished 1t will continue to be
necessary to carry all of the water
through the Lydecker tunnel from
Georgetown to Mcmillan Park in or
der to purify it at the old filtration
plant.
Even with this operating limitation.
however, Maj. James A. O'Connor.
Army Engineer officer in charge Of
building the enlarged waterworks.
declares that the use of the new
conduit is giving the city a some
what larger supply this Summer than
has been available in the past.
Shortly after the new filter plant is
in operation next year the engineers
plan to drain out temporarily the
Lydecker tunnel, which officials have
not had an opportunity to inspect for
II years.
During recent years, with the con-
sumption of water running so close
to the capacity of the old single-con-
duit system, officials hesitated to
drain the tunnel, even for inspection,
as long as it did not become abso-
lutely necessary. One of the reasons
Washington faced the possibility of
a water shortage before the enlarge
ment project was authorized a few
years ago was because the city was
dependent upon the single conduit to
bring the supply as far as the George
town Reservoir and upon this one
tunnel to convey it to the filter beds
IN Mcmillan Park.
Will Use Two Conduits.
Upon completion of the new filtra-
tion plant at Dalecarlia on Conduit
road it will be possible to supply the
entire city with filtered water from
that point while the Lydecker tunnel
is being put in first-class condition.
After the tunnel has been recondi-
toned the plan is to use both con-
duits from Great Falls and both fl
tration plants. thus giving the city a
total available supply of more than
150,000,000 gallons a day, as compared
with the $4,000, 900 gallon capacity of
the old conduit
The small appropriation of $127 800
which Congress will be asked to ap-
propriate in December will bring the
total cost of enlarging the water sup
ply up to $S,S27,600. When the
project was authorized by Congress
in 1922 it was estimated the cost
would be $9,169,000. In testffying be
fore the House subcommittee on Dis
triCt appropriations a few months
ago, however. Maj. O'Connor ex-
planned that it had been found pos
sible as the work progressed to bring
the total down to $S,S27,600.
Inspected Tunnel In 1915.
f. D. Hardy, who has been superin-
tendent of the Washington aqueduct
for many years and who is serving as
associate engineer in the construction
of the enlarged supply system, was in
the Lydecker tunnel when it was last
with interest the opportunity that will
come next year to drain it out and in
spect its present condition. This
tunnel is four miles long, extending
straight across the city from George
town to Mcmillan Park, and is 10 feet
in diameter. 1t has carried the entire
water supply of the city to the fltra-
ton plant since that plant was put in
service about 1905.
One of the most interesting fea-
lures Of the enlarged project is a
study of the differences between the
original filtration plant in Mcmillan
Park and the new one now being
pushed to completion on Conduit road.
The old plant is known as slow
sand filter and consists Of 20 filter
beds of one acre each, or 20 acres.
The capacity is rated at 10000 900
gallons per acre per day.
The new plant on Conduit road is
to be a rapid-sand filter and will cover
an area of only three-fourths Of an
acre. The capacity of a rapid sand
filter is 130.0o0,o00 gallons per acre.
New Method of Cleaning.
In order to clean the filters at the
old filtration plant workmen have to
shovel about an inch of sand off the
top of each filter. At the new filtra-
ton plant it will merely be necessary
to press a button reversing the flow
of water, SO that 1t will flush it's
way up through the sand instead of
filtering downward This process
washes the sand by causing the sedi
ment to flow over the top of the
filters After about five minutes the
flow would again be reversed down
ward and the process of filtering re-
sumed.
The new filtration plant will be
entirely inside and under a building
now in course of construction. and
which will also house new pump
ipcr Sfatinn .