Evening star. [volume] (Washington, D.C.) 1854-1972, 1906-01-31
EXPERIMENTAL PLANT
TO DETERMINE HOW TO BEST
TREAT POTOMAC WATER.
Report of Chief of Engineers on Wiley
Bill Forwarded by Sec
rotary Taft.

Secretary Taft has transmitted to the
House committee on the District of Co
lumbia report made by Gen. Mackenzie,
chief of engineers, in regard to the Wiley
bill providing for the further publication of
the water supply of the District of Column
bia.
That some auxiliary plant for the occa-
sonal preliminary treatment of Potomac
water" Gen. Mackenzie says, will be nee
essary to secure uniformly satisfactory re-
suits from the filtration plant has been
recognized from the start. There are two
general methods of preliminary treatment
of water that is to be filtered by the slow
sand process: First, by coagulatin: secoad,
by a rapid filtration through coarse ma
terial, without coagulation.
The bill as drawn provides definitely for
treatment by coagulation. While this
method will probably be cheaper than that
Of rapid filtration through coarse material
without coagulation, and while there is no
reason to believe that the use of this coag-
ulant will in any degree affect the whole
someness of the water, yet the efficiency
and economy of this system are affected
by the character of the suspended material
and by the ease with which the coagulated
matter can occasionally be removed from
the settling basin
IF this plant were established between
Dalecarlia and Georgetown reservoirs, as
proposed, the coagulated matter would be
deposited in the Georgetown reservoir, and
as this reservoir is not lined it could not be
readily cleaned Therefore the adoption OF
the coagulation method means ultimately
masonry lining in the Georgetown reser
voir
For the foregoing reasons am not rTe-
pared at this time to express a definite
opinion IS to which system should be
adopted and therefore recommend that the
Dill be modified so as to provide for the
construction of an experimental plant for
the purpose of determining the system of
preliminary treatment chemical CT me-
cnanlcal, that is best adapted TO the needs
OF the District. Such a plant will not be
expensive and will serve the purpose of re-
Heving the filter beds and at the same time
viii furnish valuable information dis TO the
merits OF the two systems so far as pcto-
mac water is concerned.
Amendment of Enacting Clause
ut is therefore recommended that the
eracting clause be amended to read as fol-
lows:
BE t enacted by the Senate and House
of Representatives of the United States of
America, in Congress assembled, That the
chief of engineers of the United States
army be, and he is hereby, authorized and
directed to construct, at such point as he
may consider advisable, an experimental
plant to determine, as far as practicable,
NiLdl SySleu Oh preliminary treatment,
chemical or mechanical, can most advan-
tageously be applied to the Potomac water
before reaching the filter beds, so that tie
latter may deliver at all times a clear and
wholesome water, and, pending the deter
mfnatlon of this question, he is authorized
to apply preliminary treatment to the Po-
tomac water at such times as he may deem
necessary, the cost of said plant, with its
operation and maintenance, to be paid from
any balances of the appropriations hereto
fore made for said filtration plant, which
are hereby made available for the purpose"
Inc Wiley bill provides for the construc-
ton of a plant for the preliminary chem
ical sedimentation of Potomac water before
being treated by the slow sand filtration
plant near the Soldiers Home. In the pre-
amble of the bill it is stated that pro-
vision for the chemical plant is based "on
the belief that the present system of fl
tration is incapable of producing clear wa
ter and Of giving the greatest bacterial
efficiency during certain seasons of the year
when the water contains large quantities
of suspended matter"