Evening star. [volume] (Washington, D.C.) 1854-1972, 1896-08-10
WASHINGTON AQUEDUCT
Captain Gaillarfs Report on the Operations
During the Month Of July.
Worst Record ~ to Turbidtty I'm the
Last Nfneteen Nears-RnlsinE
the Dam mt Great Falls.

Capt. Gaillard. the engineer officer in
charge Of the Washington aqueduct, has
made report Of operations during the past
month. in which he says that the total
amount expended for construction and
maintenance Of the squeduct and its ac-
cessory works to June 30. 1885, including
the Washington aqueduct tunnel and the
new reservoir near Howard University. was
~416367.a. OF which amount the District
Of Columbia paid 1,255. 14S76
During the month OF July the height Of
water on the gauge At the mouth OF the
conduit at Great Falls varied between 1875
feet and 1920 feet above the datum plane
table Is given of the condition Of the
water daily during July from which 1t
appears that at Great Falls the water was
very turbid for twenty-four days, turbid
Ior TOUR days. and clear for three days
tributing reservoir effiuent gate tho water
was very turbid for nine DAYS. turbi, for
thirteen days. slightly turb!d for four 6ays
and clear for five days.
Had Condition.
"A study of the records of this Office"
says Captain Gaillard. Shows that the
condition OF the Potomac at Great Falls
during the month as regards turb.dity
has been worse than during any July in
the nineteen years that the condition has
been recorded BY this office, a fact which
was also true regarding the previous
month. Except on one occasion, when the
water was purposely shut OF from the dis
trtbutng reservoir. the water level in this
reservoir during the month varied only
between 1888 and 1888 feet above datum
plane, higher mean level than has been
maintained in this reservoir during any
July since 1889. a condition due partly to
the removal of deposits from the CONDUIT
partly to the uncOmpleted work of raising
the dam at Great Falls and partly to the
slight decrease in the daily consumption
and waste Of water resulting it Is believed
from the Introduction of the additional
meters required by the distribution branch
of the water department of the District Of
Columbia.
Current meter observations were taken
In the reservoirs between the two reser-
voirs July - for the purpose of determin-
ing Tin connection with other observations
yet to be taken) the co-efficient C In for
mIla V--C r S, in order that the daily
and hourly consumption of water can be
determined hereafter from gauge readings
at the two extremities of the conduit with
out the necessity of shutting Off the water
from the distributing reservoir and low
ering its level over three feet during the
pre- gress of the measurement
EStims ties of materials for inserting the
valves and blow-offs in The thirty-inch and
thirty-six-inch mains have been prepared.
and correspondence is now In progress
Win view 10 securing special appara tuS
Tor inserting the valves and blow-offs with
out demonstrating consumers by tenn
porarily shutting of their water supply"
Raising the Dam at Great Falls.
In regard to the project for increasing
the water supply of Washington, D. c., by
raising the height of the dam at Great
Falls. Capt. Gaillard says that operations
we're prosecuted with great disadvantage
curing most of the month, on account of
figh water in the Potomac, the reference
of the water surface behind the completed
PORTION of the dam varying from about
1D.1 feet to 1910 feet in the Virginia cham
mel, and from l49.5 feet to l.o.O feet in the
Maryland channel. Because of this state OF
anatrs 1t was possible to lay masonry on
that part of the dam across the Virginia
channel on but three days only during the
Maryland channel only between July l and
81
The floods which caused so much damage
a1ong the upper portions of the river in
ficted no injuries or loss of property upon
the works at the dam except the loss of
some of the rip rap pavement which is laid
In advance of the masonry in order to pro-
coping stones from the rush of water over
the dam This rip-rap is never displaced,
even against a read of several feet until!
the water begins to pour over its crest to a
depth or foot or more. when the stones
on the down stream slope are then dis
placed and frequently carried over the
dam. Two hundred and fifty lineal feet of
dam were completed in July. of which l.D
feet were in the Maryland channel ard ~
feet in the Virginia channel. The total
length OF dam now completed is 1,644S
lineal feet.