Evening star. [volume] (Washington, D.C.) 1854-1972, 1931-03-29
Survey of Mains Beginning
in Month to Cost $4,000
in Four Years.
TOTAL OF 6,8e5,6O1 900
GALLONS LOST YEARLY
Special Instruments Will Locate
Breaks and Measure Flow.
Will Work at Night.

under the authority of the current ap-
preparation bill which provided $40,0 900
for start on the work. The personnel
for the survey has been appointed but
transport and instrumnts have not yet
been purchased. The latter are ex-
pected to be delivered soon.
The survey will last four years and
will cost ultimately 100000. AS re-
suit of repairing the leaks discovered,
1t is expected that saving of 100000
gallons a day may be effected and sta
tisticians of the Water Department say
that such a result would yield return
of IL per cent on the investment in the
survey.
Many of the members of the field
force are now doing duty with the
maintenance division of the Water De-
partment in order to familiarize them
selves with this type of work. All Of
the work o fthe field parties will be
done at night. Starting at midnight a
field party will take a predetermined
area, containing perhaps fifteen city
blocks and by system of shutting oil
valves isolate the flow of water into one
or more of the blocks to a single main,
or perhaps to two mains. The flow OF
water into the area is measured by two
instruments, Pilot tube and mano-
graph.
Measures Water Flow.
The Pilot tube is device for measur-
ing the speed of the flow of water. The
end of the instrument inserted in the
water main, as shown in the picture,
has two openings, one facing the flow
and one facing away from it. Each
orifice leads into a steel tube. the ends
of which are connected by rubber tubes
to a U-shaped tube containing mercury.
When there is no flow, the preSsures on
both openings are the same and the
mercury in both branches of the U tube
remains at the same level. When water
is flowing, the pressure on the opening
facing the flow is greater than the
pressure on the other opening. This
difference in pressure depresses the level
of the mercury in one tube and raises
1t in the other. The difference in level
Is then measured and multiplied by a
factor which yields the number of cubic
feet or gallons flowing in the main
per second.
The Monograph records on paper the
observations made by the Pilot tube.
Part Of this instrument Is a pen which
makes a red mark on rotating chart
is connected with metallic plunger.
The plunger dips down until it makes
a contact with the mercury which COM
pletes an electrical circuit and takes the
pen back to the starting point Varia-
tons In the level of the mercury result
in variations in the marking on the
chart, and from the chart by applying
appropriate factors the flow of water In
cubic feet per second may be read.
When the fiow in one block has been
measured for q while, valves are opened
so as to let in another block, fed from
the same main or mains. The combined
readings for the two blocks are taken.
Then other blocks are let in one by
one, and the readings mount higher
and higher. If there IS any extraor-
binary jump from one block to the next,
it is probably sign that a leak is
causing 1t. Perhaps, however, there
is some other cause. the presence in
the block of a hotel, or some other
establishment open all night. Meter
readings OF the various houses and
establishments in the doubtful blocks
are then taken, and II there is still I'M
accounted for water shown on the
Monograph, the search for the actual
leak begins.
Third Device Finds Leak.
This is accomplished by use of a third
device, the aquaphone. This looks Ike
an ordinary telephone receiver. but
has no electrical connection. 1t Is a
simple device for magnifying sound.
BY listening with one metallic end Of
the aquaphone pressed against a water
main, IRE hydrant or any other direct
metallic contact with the water main,
the inspector Is able to locate the leak
exactly. Somettms, in order to listen
at the right place, it IS necessary to
drive an iron rod down through the
pavement until it rests on top of the
main.
The work of making these readings
will be undertaken by two full field
parties each consisting of chief, two
inspectors and two laborers. In the
ONCE there is an assistant engineer
in charge, assisted by two aids. over
the entire organization is Paul Lanham,
who has devoted many years to this
type OF work, and is the inventor of the
Monograph.
Getting down to statistics, those for
1880 are fairly typical for the four
years previous. Out of 29, 800, 705, 900
gallons delivered, $685., sol 900 gallons
were absolutely unaecounted for. In
addition TO this there was an estimated
leakage to be expected in any water
system of 555,294 900 gallons, claSsed
as allowable leakage, the Federal
Government took 1928 las, 900 gallons;
the District government took ,802,-
093, 900 gallons. and the balance, or 49,
AL ,568 900 gallons were actually paid
for by consumers. Thus of the entire
water flow, only 54.8 per cent was paid
for; per cent went to the District Of
Columbia; 143 per cent to the Federal
Government; 1.9 per cent was regarded
as allowable leakage, and % per cent
unaccountably vanished,
Will Miss Some Leaks.
No effort will be made to discover
each individual leak in the whole sys-
tenn, as the cost of such an undertake
ing would probably be prohibitive. Even
in territory that has been carefully sur
veyed there will be leaks which viii
Rave originated after the surveyors left
the territory. But the officials put the
probable saving conservattveiy at TO-
600 900 gallons per day. The total value
of such an amount of water for a year
Is put at $40, 90. taking into account
the cost of pumping, chemical treat
ment, filtration and the like, and the
added cost of electric power owing to
shortage of water at the hydroelectric
station.
During the four years of the survey
it is expected that $53,238 worth of
water will be saved. leaving the net
cost of the survey ST., $50. The saving
OF s29,l69 annually after completing
the survey Is therefore, on the net cost,