Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-05-12
LOCAL WATER SUPPLY
Capt. cosby's Report of Daily
Production.
CONSUMPTION AND WASTE
Total of e3,400,0o0 Gallons Per
Twenty-Four Hours.
DETAILS OF CLEANSING WORK
Cost Of Operating Filtration Plant
Greater Past Month Than Pre-
viously-An Explanation.
DETAILS OF CLEANSING WORK

According to Capt. Spencer Cosby, the en-
gineer officer In charge of the Washington
water supply system, the consumption and
waste of Potomac water during the month
of April averaged about GO 100000 gallons
per twenty-four hours. During the month
the height Of water on the gauge at the
mouth of the conduit at Great Falls has
varied between elevation 1880 and eleva-
ton 1870 above the datum plane. The
height Of water at the Washington city res
ervoir has varied between 1880 and 1879. 40
above the datum plane.
In his latest report Capt. Cosby gives some
details Of the work of cleaning out and re-
pairing the main conduit from Great Falls
to the Dalecarlia or receiving reservoir,
which was performed during the past month
without the slightest interruption to the
water supply of the District. He says that
all the gates to the conduit at Great Falls
were closed at pm. April % and the gates
at waste weir No. opened and the conduit
was allowed to empty. The next day the
conduit was cleaned from the gatehouse at
Great Falls to bridge No. 8. About fifty
cubic yards of mud and about six cubic
yards of rock were removed. That rock had
become loose and fallen from the sides and
roof of the conduit. About 5 pm. April 20
the gates at waste weir No. l were closed
ana gates at the intake opened and the con-
ooAt was o1ioWSu " al bdlGCdTlia res
ervoir small repairs were made to the con-
duit road and the wooden bridge That
bridge was rebuilt about ten years ago and
Capt Cosby says. is now In need of perma-
nent repair. Bins and screen for crusher
have been taken down and moved to the
quarry above bridge No g.
At o'clock pm. April % stop timbers
We're put In at the north connection and
wicket gates opened at waste weir No. 2
and the conduit was allowed to empty The
men who opened these wickets had to re-
main IN the chamber two hours and half
April "a and rs the conduit was cleaned and
inspected from bridge No 8 to waste weir
No. 2. About twenty-five yards of mud
were remived, mostly from the large I'M
lined section near waste weir No q Cracks
IN the conduit over culvert No. 20, showing
movement since last pointed up, in Septem-
Der, 1906, We're very slight, as were the
cracks In bridge No. 4.
Coat Of Cement Wash.
The conduit over that bridge was washed
with a coat of cement wash and cracks
were pointed up. Capt Cosby says that had
a good effect and the leakage is now very
slight. At $50 am. April 20 the water
reached waste weir No and was allowed
TO run for two hours and a half to flush ont
the mud which had been loosened after
Whlch the wlckets were closed and water
was allowed to enter the reservoir. The
water in that reservoir had fallen TO eIeva
uon l403O. and with the water at that ele
vauon there was none in the channel
dredged at the north end of the reservoir
elevation of the bottom OF the obarraI -,
about 14l so e
with the exception of one period of two
Gays duration the turbidity of the Potomac
river water at Great Falls was rather low
Tor me entire month. That period occurred
April 10 and IS, when the average turbidi-
ties We're II. 20 and $40, respectively The
turbld water during that period was ex-
GUIDED from the aqueduct system by clos
ing the gates at Great Falls for two days
The turbidities of the several reservoirs
have not been excessive at any time during
the month, while those for the filtered
water averaged 7. which is slightly greater
than that OF the previous month.
Bacterial Contents.
The average bacterial contents of the
water at Dalecarlia inlet and outlet and at
the filtered water reservoir were somewhat
greater than during the previous month,
while those OF the Georgetown and Wash
ington city reservoirs were less. The In
crease in the filtered water reservoir, how
ever was SO slight as to be hardly worth
noting, being only from 10 to % bacteria
per cubic centimeter.
Bacillus coll (the typhoid GERM were
found In greater number In April than in
the previous month, In all cases, with
the exception of the tap water. The aka
Unity and hardness Of the water was q
little lower than during the previous month.
The lengths of runs of the filter cleaned
in April were somewhat greater than those
for any month since the plant was put into
service. It seems probable, however, that
they will decrease as the temperature of
the water rises on account Of the increased
growth of micro-organisms.
The cost of operation per million gallons
of water filtered was greater than for any
previous month, owing to the increased
amount of sand handled in cleaning the
filters The average daily amount of water
pumped to the filters was 81, 100000 gallons,
or / $50 600 gallons less than for March,
but the amount of work was greater on
account of the sand washer pumps and
electric washing.